Saturday, March 31, 2007

YOU'VE GOT TO BE KIDDING...
EASTER COLDER THAN CHRISTMAS ?!?


While I can't claim ownership to that headline (Joe Bastardi of Accuweather alluded to it first) the indicators are clearly there and shown on the GFS projection for early Sunday morning, April 8. As I mentioned in my blurb last week... frost on the bunny ears is looking more likely. In Baltimore, the daily high temperature recorded at BWI for December 25, 2006 was 50 F, and the 24-hour low 30 F. In Philadelphia, the same numbers were 49 F and 33 F respectively. If the upper level 540 thickness line (dashed blue line below) does get to the Virginia/NC border as shown, I would expect the map above to verify fairly closely. That means Easter morning the Mid-Atlantic may be looking at widespread 20's and just breaking into the mid 40's by afternoon. But wait! It gets worse. (I know, I wish this was an April Fool's joke, but it really is not.)
gfs_slp_192s
You should know both the GFS and Euro have begun to advertise a fairly intense (and unwelcome) cold snap to enter the Great Lakes, Mid-Atlantic and Northeast by late in the week, starting as early as this coming Thursday. This may be followed by a series of Low pressure systems forming along the southern boundary of that cold air. The map below is a 10 day hint of snow possibility on or about Tuesday, April 10, but it is just a very early projection.

As with all storms, this one will need "the right amount of cold and moisture at the right times." Yes, I know you're thinking "how could this be, a snowstorm in APRIL? Come on." Well, April 6 in 1982 and 2003 produced memorable snows in east central PA and New Jersey. In fact as late as April 23, 1986 there was an an inch of snow that morning at my home in suburban Philadelphia, and northern New Jersey/southern New York received 2 feet of heavy wet snow from the same storm. I remember this well because exactly one year earlier on the same date in 1985, Philadelphia recorded a record high of 94 F along with many other cities in the Northeast.

So despite the strength of the April sun, there can still be snow this time of the year and this will no doubt dishearten the spring-a-lings like me who are ready to start planting and are so totally done with the snow this year. In fact I even reverse-jinxed the storm because I told my wife, "Look dear, I'm putting away the shovel and salt (for the second time)...that means it'll snow one more time." Thus the Adventure of Winter 06-07 continues yet again, so stay tuned and this coming Friday we'll revisit the potential of a final? snowstorm once my quarterly grade scans are done and in on time.

Tuesday, March 20, 2007

WINTER RETURNS, JUST IN TIME FOR SPRING
images courtesy of Accuweather.com

Equinox Week 2007

An early week update to say that Monday night's clipper through the Great Lakes and Northeast brought with it a temporary chill which will make the first full day of Spring (Wednesday) feel downright January-ish. Highs in my area of Maryland are only expected to reach the mid 40's with lows once again in the mid 20's. But fear not Spring-a-lings (a term of endearment for members of the discussion community who favor Spring)...your long awaited warm-up will return for a brief time late this week and into next week. As we head towards the end of March and Palm Sunday Weekend, there might be some April Fool's mischief lurking in the time frame from the 30th to the 3rd, and it's no joke that this inappropriate meteorological behavior could include SNOW for portions of the Mid-Atlantic and Northeast. More on that mayhem later, for now we can finally celebrate the arrival of "Astronomical" Spring at 8:07 PM EDT today.

Sunday, March 18, 2007

MARCH 16-17 STORM GRADE REPORT

Final Snow/Sleet Totals across the Northeast, as reported to PSU's Public and Spotter Page.

March 16-17 Snowfall Map

This storm report is based on a procedure we've established on the site since since 2005. The actual amount is graded by it's % deviation from the forecast, and then grades on a GPA scale. Now in fairness...we have not yet reached consensus on the discussion board here if the grade should be actual accumulation of just SNOW or can it be SNOW & SLEET or just SLEET. Obviously the 2 recent storms have retrained everyone as to what sleet is and can do to a forecast.

Also in fairness…please note I don’t just pick and choose among the best actual observations. Frequent long term readers know and can vouch for the fact that when I say “NYC / Boston / PHL ” I have used the same locations each storm… NYC = Central Park / Boston = Logan airport / PHL = airport. The other locations are from members of the discussion community based on their obs posted in the comments.

Just for a new reader to know there’s no sugar coating here. The numbers speak for themselves, good, bad or ugly.

The numbers are: Final GPA / City forecasted / amount forecasted / actual / %dev / grade

The GPA is determined by the standard 4.0 academic scale:
4.0 A / 3.67 A- / 3.33 B+ / 3.0 B / 2.67 B- / 2.33 C+ / 2.0 C / 1.0 D / 0.0 E

0.00 / Baltimore (BWI): 2.0 / .6?/ 70%/ 30% = E

3.33 / Dundalk, MD: .75 / .85 / 12% / 88%=B+

0.00 / Philly (PHL): 6.0 / 3.0 /50% / 50%=E

2.33 / New York (Central Park): 7.0 / 5.5 / 21% / 79%=C+

4.00 / Boston (Logan): 8.0 / 8.1 / 2% / 98%=A

0.00 / Greencastle, PA: 9.0 / 5.0 / 45% / 55%=E

2.00 / Martinsburg, WV: 10.0 / 7.0 / 30% / 70%=C

2.00 / Paoli, PA: 7.0 / 5.0 / 29% / 71% = C

0.00 / Bucks Co, PA (Doylestown, PA) : 11.0 / 5.7 / 49% / 51%=E

1.00 / Central NJ (New Brunswick): 6.0 / 4.0 / 34% / 66% = D

0.00 / Fallston, MD: 4.0 / 1.0? / 75% / 25%=miserable E--- sorry Terpguy

So despite your claims that “this guy is always right!” you can plainly see that is not true!

Storm Forecast GPA = Less than thrilling 1.33 / (some would say, it’s at least passing! But far less than the C average of the February 11-12, 2006 Storm or the January 2005 Blizzard.

WHITE FOR ST. PATRICK'S DAY,
THEN BACK TO GREEN, then white again?

So your 2 week forecast should have been something like this:

THIS WEEK: 80's then much colder with rain changing to snow and sleet.
Keep scrolling to see the forecast for next week and beyond.

St Patricks Day Morning 2007

Ice-encrusted backyard of "Fort Jackson" as we call it (named after our street)

Mid Atlantic Surface Temps Sat 3-17-07

Seems like I've posted this same map before, a couple times this winter.


NEXT WEEK: Chilly and a bit cloudy until mid-week, then sunny and becoming warmer by late in the workweek. Mid 70's by Saturday from southern PA south to Richmond, near 70 Philly to NYC, 60's from NYC north to Boston.

( I knocked out my claim to 90 because the clipper coming across Great Lakes Sun-Mon will reintroduce second High I theorized early last week, holding mid-week temps down a bit)

A Spring Fling

WEEK AFTER: Turning colder with snow possible by Palm Sunday Weekend?!?!?

Palm Sunday Weekend 2007

What part of this forecast is an early April Fool's Joke? Well, the snow part I hope. I found those maps on a weather discussion board called Eastern US WX, so I am not claiming to have discovered the info on my own. But I thought the extremes were so interesting you just had to see them. I can see how we COULD warm up into the 70's, if the Polar Vortex near Alaska goes to town strengthening onshore Pacific flow into the West while the Atlantic Ridge becomes the major influencing player for much of the Eastern U.S. Concurrently, if the North Atlantic Oscillation and Arctic Oscillation remain strongly positive the next 7-10 days, this would also allow warm air to surge across most of the country. These climatic features are a measure of how much the Icelandic Low and Atlantic Azores High "oscillate" back and forth across their portion of the Northern Hemisphere over a period of time. If the NAO goes positive, it means the Labrador-Icelandic Low would be retreating north, holding the Polar Jet in central/northern Canada. Thus the Azores-Bermuda High can take over and influence weather more along the East Coast.

As for the theorized Palm Sunday Weekend storm...well, sometimes long range (7 day+) model projections are to be taken with less than a grain of salt. In fact, you can't even use salt this time because Home Depot ran out weeks ago. I tell you about this storm purely for entertainment purposes only, because the GFS has shown on just one model run this morning, from Hour 324 to 372 (weekend of 30th) a possible snowstorm for the Mid-Atlantic and Northeast. The only shred of "future evidence" that could back up this outlandish claim is the NAO/OA are both forecasted to strongly tank negative by the 30th. Sometimes 14 day projection on the Climate Indices/Teleconnectors never pan out or even trend in the opposite direction, other times they are verify fairly well. So were the NAO/OA to go 2 deviations below normal like that, it is would indicate cold air might again invade the Northeast U.S. just in time to disrupt plans for Palm Sunday Weekend. This all sounds like a skipping CD I can't clean off, and I'm not buying that scenario anyway (that's analogous to a broken record for our more seasoned readers) so I'll stop there and revisit in 7 days.

Friday, March 16, 2007

MAY THE LUCK O'THE IRISH BE WITH YE
(IF YOU WANT ONLY SNOW FROM THIS)

8PM Friday evening comment: The Mid-March Maelstrom has proven to outmatch my forecasting abilities at present. By the time I will have figured out everything that should happen with our storm, it will already be over. I do feel vindicated in the sense that this was either a good call or a lucky call pegging the time frame for this event 11 days in advance.

(Quote from March 7: "I should also warn teachers, athletic directors and coaches that there is a lot of "March Madness" lurking out there in the 15th-20th time frame and it's not looking pretty. More on that later but let say for now I may have to retract my claim of "That's All Folks" from last month.")

I regret not being able to post my overview of the March 1956 storm, it would have been a great comparison as snowfall from this one will closely match or beat that one. The situation has been so changeable the past 24 hours I didn't feel confident enough to come out swinging with region-wide snowfall forecasts.. but here's what was said or written to a few people including my students either in person or in the comments over the past 2 days: Baltimore: 2 - Dundalk, MD: .75 - Philly: 6 - New York: 7 - Boston: 8. Tonight I'll add Greencastle: 9 - Martinsburg, WV: 10 - Paoli, PA: 7 including sleet - Bucks Co, PA: 11 - Central NJ: 6 including sleet - Fallston, MD: 4.

A special sorry to Mr. B in Greencastle..he had a nice writeup but I didn't post it in time, so I will in the after-storm wrapup. Part of the reason for my lack of progress in updating you on the storm since Wednesday was a time-consuming outdoor landscaping project at our school this week, appropriately timed with the weather of course. I also am a bit behind in an online graduate course, so a lot of mental energy went to those two undertakings. Despite all this, I am glad the forecast somewhat verified in that many members of our online community are receiving their well-deserved (and likely greatest) snow for the season, albeit a bit late. But I am also sad to say this is :::probably::: the last float in the winter parade. Sad in the sense that once we get past this, the website will be going dormant for a while. The quietest time of the year on here is now to about August, or whenever the first tropical system begins to flare and make faces at the U.S. Atlantic coast. Until then, my focus shifts to spring preparations, greenhouse work, landscaping, final exams and closing out school for the year. So enjoy the final hours of your final storm of the winter that's finally done in about 4 days.

Accuweather Radar from this evening. Compare to that of this morning below.

Mid-Atlantic Radar 615 PM Friday 3-16

It took a while for the boundary layer to cool, hence the reason your radars all looked pink and white while you only saw rain at the ground. We had a tough time convincing students at our school in southeast Baltimore County WHY we had let out 2 hours early. Though it was raining buckets in Dundalk, the other 2/3rds of the region were seeing rain changing to snow. Combined with the flood warnings, heavy snow potential, sleet and extensive traffic accidents which occured in the morning, those factors were scary enough that school officials apparently decided they had better get ahead of this storm before it got ahead of them. I read in the comments that other districts decided to close outright before hand and for those areas (in WV, southern PA) that was definitely a good call.

Friday 3-16-07 Radar

The 8PM projection from the GFS (Global Forecast System) shows the cold air hanging tough despite our vigorous Pre-St Patricks Day Storm rolling quickly up the coast. This is not a current observation map of course but a short range (6-hour) model printout of expected conditions. Note position of the 850 millibar 0 C isotherm... right over 95. I imagine all this sleet is resulting from the strong easterly flow off the ocean crashing right into that cold air, and happening so fast, and with the atmosphere so wet, snow does not have a chance to form. For those who are seeing snow this evening (which appears to be almost everyone but my town).,. your ratios are probably going to be 8:1 or even 6:1, but with 1" of liquid you could still pull 6 inches out of this.

GFS Model Projection for 8PM Friday 3-16-07

Now, just for fun...here was the original GFS model projection for early this morning, but generated about 6 days ago by the computer. Though the timing is off by 12 hours here, note the interesting differences.. the Great Lakes Low was projected to hang on longer and block the cold air advance to the Mid-Atlantic. The High in Quebec that we see tonight...was nowhere to be found. This is why your local forecasts said nothing of the heavy snow, sleet, grauple, ice pellets, freezing fog, whatever kitchen sink type storm you have there.. because like it or not, Accuweather's 6-10-15 day forecasts as well as the Weather Channel's "The Week Ahead" portion of your local forecast are ALL TIED TO THE GFS. It only began trending colder about 72 hours ago if that. Truth is, the GFS missed the big warmup (84 F in Baltimore Wed) but finally caught on to the colder trend by Thursday.

GFS Model Projection for Fri 3-16


FRIDAY 6:00 AM STATEMENT: My biggest concern with this storm is the cold air is pulled into the Mid-Atlantic region, especially along I-95 and north/west of the cities from DC-Philly, changing the rain over to snow more quickly than expected. This brings winter weather advisories or even instant "Winter Storm Warnings" to areas that were only expecting an inch or two, such as DC and Baltimore. I'm not hypecasting, just thinking that the easterly track as was the trend overnight continues, resulting in a Friday Blitz that leaves your St. Patrick's Day more White than Green. you're in the "Nowcast" Zone now. Forget your local forecasts and just follow the radar today, especially Accuweather as shown above, it will give you the best indication of what is happening at the critical 850 millibar level of the atmosphere where the dynamics may lead to this rapid changeover to snow earlier than later today.

Last point...I THINK THERE IS A STRONG POSSIBILITY MANY METRO AREA SCHOOLS MAY HAVE TO HASTILY SCHEDULE AN EARLY DISMISSAL BASED ON RADAR TRENDS.

(8pm comment: that one worked out well.)

Thursday, March 15, 2007

MORE WHITE THAN GREEN
THIS ST. PATRICK'S DAY

St. Patricks Day Storm Snowfall 2

The Weather Channel's current snowfall projections, of which I generally agree, and will be adding a roundup of site-by-site predictions for the Mid-Atlantic this evening, along with analysis and potential impacts to school on Friday as well as Saturday activities.



COULD THIS BE WHAT'S IN THAT POT
AT THE END OF THE RAINBOW?

St. Patricks Day Storm 2007

This morning's (12Z) North American Mesoscale (NAM) 84-hour model projection for snowfall this weekend by 8PM St. Patrick's Day. For those of you wanting one more snow, looks like the luck o'the Irish will be with ye. Though the event is 48 hours out as of this writing, the Boston NWS has issued Winter Storm Watches for their forecast area, and everyone who pays attention to this stuff throughout the Mid-Atlantic has begun to hear the first mention of snow in their weekend forecasts. Hard to imagine I'm sitting with the windows open, enjoying what feels like a mid-summer breeze, looking at the current temperature of 71 F, and writing to you about a SNOWSTORM on Saturday. Doesn't get more surreal than that, now does it? My colleagues at school recall that in the days preceding the March 1993 Superstorm (14 years ago this exact moment by the way), they were walking around Baltimore's Inner Harbor in shorts. But even then temperatures in the days prior to that storm were seasonable 50's and 60's. Today at my school, we hit 85 F in the sun and 80 F in the shade, and it was great fun telling students and teachers... "Ready for a White St. Patrick's Day? Har de har har."

As with every Mid-Atlantic and Northeast Storm, this one is bound to be just as complex as all it's predecessors. It has been a busy week and I will endeavor to revise my analysis from the previous post below for this late-season blockbuster which I have maintained since Sunday has the potential to deliver some areas their highest 24-hour snowfall of the year thus far.

REGIONAL SUMMARY Posted 10:02 PM 3-14-07
by Northeastern Forecasting Correspondant Mr. E.H. of Boston, MA.

Overall, it looks like Southern New England and possibly New York City's suburbs will be getting the most snow out of this storm. Those areas will receive their biggest eastern snowfall of the year this weekend and on St. Patrick's Day to boot! However, there will be enough cold air for the Mid-Atlantic once this storm gets its act together off the coast on Friday that areas near or just slighty to the WNW of the cities of Baltimore and DC will see a little wet accumulating snow. Philly and eastern PA may pick up their healthiest snowfall of the season as well with the heaviest snowfall totals to the north.

Into NYC, it looks like there will be advisories and warnings being posted, especially just to their north and northwest. Snow Advisories and Winter Weather Advisories will likely extend all the way down in MD and VA as well. Instability flurries and snow showers will encompass all of the OV and Great Lake states this weekend and will likely deliver a couple inches of snow to this region as well. Eastern TN may even see some accumulating snows this weekend as well! Winter is not over yet.

NORTHEAST SUMMARY: by Forecasting Correspondant Mr. E.H. of Boston, MA.
I am seeing this storm affecting Southern New England (SNE) in 2 rounds.

THURSDAY: ROUND 1. Starts in earnest tomorrow afternoon with rain, moderate to heavy falling along with falling temperatures into the mid 30's by late PM. Rain changes to snow late Thu night and accumulates to the tune of 2-4" Boston metro by the Fri AM rush.


FRIDAY: ROUND 2. Maybe a lull until early PM in SNE then heavy snows move in for the area. Rain on the Cape. Snow accumulating quickly. Late Fri PM, time of the 6 hour period of possible changeover for eastern SNE. Not sure this will happen for areas just WNW of Boston. These areas may be all right for mostly snow. Another 6-10" of wet snow possible with this round.

So, my preliminary forecast is for a general 8-14" of snow for the Boston-Worcester-Providence-Hartford areas by the end of the storm late St. Patrick's Day night.


ANALYSIS: Posted 8:43 PM Tuesday 3-13-07 by Mr. E.H. of Boston.


Snowfall accumulations look to be in the low to moderate Warning criteria for Southern New England. A Winter Storm Warning would be issued in SNE when 6"+ is imminent if the when the Watch was issued at least 12 hours prior and 8"+ is imminent when it is forecasted 24 hours or more prior to the onset.


What I am thinking is that there is a seperate rain maker that moves in tomorrow for Boston and SNE that delivers locally heavy rainfall after highs will range from 70-75 degrees. That lingers as scattered rain showers during the day Thursday with highs in the 50's and dropping by the evening rush. Thursday night there is still spotty showers and a few of these showers may turn to snow showers and flurries, especially in southern NH and VT Friday morning. Then there will be a lull in the action most of the day Friday before the heavy duty snow falling at temperatures of 30-33 moves in. That will continue all night Friday night into the early afternoon hours of Saturday possibly ending as a period of drizzle for eastern SNE. The critical rain/snow line will probably be around Plymouth to the SE portion of MA and RI.

To the north of there, there will be strong NE winds off the nice and cold 37 degree ocean water and with a high parked perfectly over Quebec, enough cold air will be here from Hartford to Providence to Boston for a good sized snowstorm. Still early, but it looks like this type of snow will be very wet with snow to water ratios of 6:1 SE and 8:1 in northern SNE.


Further north into NH, VT, and ME may see ratios of 15:1, but that is where less in the way of snow will fall, the way it looks like at this point. This all moves out Saturday night and we fall rock bottom into the single digits both below and above zero in NNE to teens in SNE. 20 in the cities. Sunday will be the day of digging out if you haven't already or just wait for the sun to do its job. Its almost April for goodness sake...the snow will be melted in a few days!


Nonetheless, highs Sunday and Monday will be quite cold with highs in the mid to upper 30's with breezy NW winds making it feel like we are in the heart of winter again. We stay "cool" until the end of next week, and then it looks like we will warm up the whole country again, back to normal and above normal temperatures. 50's and 60's in the NE...60's to around 70 in the MA.


--end forecast and analysis from Mr. E.H. -- Many thanks for a fabulous and comprehensive overview! I could not have put something together this quality in the time available so the spotlight for this storm is all yours!


For Feedblitz subscribers, in the interests of time and brevity, this post and the one issued earlier in the week are going to be revised with current information. While you'll receive this message in your email, you'll need to go back to the website to receive the most up-to-date details as this and the post before it are going to be updated several times over the next 2 days.

Sunday, March 11, 2007

ISN'T IT LOVELY?
LIKE THE GOOD OLD DAYS OF JANUARY...
UNTIL WINTER RETURNS NEXT WEEK,
JUST IN TIME FOR SPRING!

UNINTENDED BENEFITS OF AN EARLIER DAYLIGHT SAVING:
* An extra hour of daylight to do your pre-garden prep work in the nice warm weather.
* If there's a late season storm, you'll also have more daylight to shovel or sled!

March 2007 Warmup 2

EXECUTIVE SUMMARY: Concensus has been growing among public and private forecasting agencies as well as through model indications that the period March 16 - 24 looks to be very stormy, potentially snowy and progressively colder for a majority of the East Coast. The "false warmup" that arrived Saturday the 10th and continues into Wednesday, though very pleasant, will set the stage for a 7-10 day series of late season cold blasts interspersed with winter storms. Oddly enough, those storms might even occur OUTSIDE astronomical winter (on or after March 21) and could potentially deliver to the central Mid-Atlantic and coastal Northeast their largest accumulations of the year. The period of Sunday the 18th through Friday the 23rd may be very cold and disruptive, and temperature records may be challenged for areas which just recently observed all time lows for the month of March.

REGIONAL SUMMARY

- Ohio Valley and Great Lakes: Warmth early in the week will lead to this area becoming the battleground zone to be sure for the period 14th to 24th, alternating between rain and mild / snow, windy and colder with the passing of possibly three distinct systems over this time.

- Mid-Atlantic: Later in the week, interior and Appalachian areas will see changeovers to snow in frontal passages, then a turn to colder, while coastal areas end up with rain changing to snow for a brief time, then much colder with a possible storm around the Equinox.

- Northeast: The warmup will be shortened by arrival of the first system in midweek, followed by progressively colder and windier conditions. Snow is possible one day late next week, much colder following next weekend with the potential for a coastal system around the Equinox.

SYNOPSIS OF STORM EVOLUTION AND DYNAMICS
This discussion will contain a considerable number of computer model maps to illustrate the situation to unfold over the next 7 to 10 days. I do want to say that while long range computer model projections are not to be taken 100% literally, they do give us an indication of what pattern changes may be in development. Granted all the maps I have included will change numerous times between now and onset of the event. However I feel confident that the upper level dynamics in place strongly point to a significant late season disruption of the normal climatic pattern of gradual warming we have come to expect for this time of year. The changes being presented starting late next week will be unwelcome for many who are looking to put this winter behind them and move on to Spring.

Premise of the forecast: The false warmup from Sunday to Wednesday sets the stage for a cold, stormy and snowy period starting the 16th and continuing for a 7 t0 10 day period. Factors that will lead to the development of this pattern, in chronological order are: (1) Activation of the Southern Jet Stream; then (2) Buckling of the Polar Jet; followed by (3) Arrival of new Clippers; and finally (4) Moderating first High leads to stronger and colder second High and possible "pattern-ending" snowstorm to usher in the Spring Equinox.

1. Activation of the Southern Jet Stream due to a surface Low and upper level low in Texas that moves slowly across the southeast, allowing warm moist air to surge into the Northeast. The early and mid-week warmup across a large part of the Eastern U.S., will see temperatures climbing into the 60's and 70's to even near 80 across the Mid-Atlantic with overnight lows well above freezing. Consider the Saturday 3/10 late afternoon temperatures across Mexico, the US and Canada. Early evidence of my theorized pattern change is the slug of warmth pushing across the Baja and into Texas. Warm air coming across the subtropical Eastern Pacific means there's going to be more moisture becoming available for the next system that moves into the Gulf towards the end of this coming week.

March 2007 Warmup

2. Buckling of the Polar Jet. Although warmth will have overspread much of the country by Tuesday, it will exit as quickly as it arrived by end of the week. A vigorous low moving through central Canada as shown in the European projection below will provide additional strength to the warm air advection. However it's counter-clockwise flow on the backside will be the first domino to fall and initiate a surge of cold air along the first in a series of clippers to cross the Great Lakes and Ohio Valley into the Northeast. This buckling of the polar jet will lead to the demise of the weak cross-continental "zonal flow" before it has time to help establish a warmer regime.

European Model Projection for Tue 3-13

Concurrently, an upper level and surface low is projected to be moving from Texas to the Southeast during this time period. Upper level lows are notorious for moving slowly, thus allowing the surface low to tap and enhance moisture transport from the Gulf into the Tennessee and Ohio Valleys in advance of the progressing cold front. This is indicated by current QPF projections as well as by the GFS surface projection for Wednesday the 14th. Note that with each passing day this week, these links will automatically update with the most current changes as progged by government forecasters at NCEP.

GFS Model Projection for Wed 3-14

3. Arrival of "Clippers" turned "Coastals." This first Great Lakes clipper will usher in a strong cold front through the Mid-Atlantic and Northeast on Thursday and possibly as early as Wednesday. Rain that starts along I-95 on either day may even change over to snow for a brief period before the day ends, and interior sections of Maryland, central/western Pennsylvania may end up with a few inches of wet snow as the front passes overnight Wednesday or Thursday. This trend has already begun in local forecast grids from NWS offices in State College, PA.

GFS Model Projection for Sun 3-18

Behind this front will be the first in a series of cold surges to plunge into the Northeast starting on Friday the 16th, followed by a second and colder Arctic High Sunday into Monday. Temperatures by Sunday the 18th across much of the eastern 1/3 of the nation may be 10-15 degrees below normal, which is to say if you're in Philadelphia, an average high right now is roughly 50*F. Using Accuweather's 6-10 day outlook for example, by next Sunday you may be looking at highs in the upper 30's to low 40's and lows once again in the 20's.

4. Moderation of the first Arctic high by Tuesday the 20th ushers in more moisture from the Gulf, which may lead to a stationary frontal boundary between a warm moist air mass in the Southeast and the incoming Arctic Highs. Several weak areas of low pressure may develop along this front, transporting precipitation from the Gulf into the Tennessee and Ohio Valley and eventually into the Mid-Atlantic..as indicated on the map below. Of course, this is a 10 day outlook and those of you skeptical about this verifying are rightly so. I'm showing this just as one piece of an overall larger picture of the pattern evolution.

GFS Model Projection for Wed 3-21


While I agree with skeptics that precise forecasts more than 10 days out are haphazard at best, it remains to be argued that if unseasonably cold air is firmly in place across the Northeast, it is probable that one or more systems moving from the Gulf may eventually result in interaction between the southern and northern branches of the jet stream. Some indication of this scenario is revealed on the GFS projection for Wed 3/21 and Thu 3/22. Whatever precipitation falls on your home, whether it is rain or snow during this event, re-freezing is possible given the arrival of a second very strong and cold Arctic High following the 21st and 22nd. This last stage of cold in the 16th-24th period may reach it's maximum intensity by the weekend of the 23rd, especially if widespread snowcover has been established prior to the arrival of this final Arctic High. Keep in mind it would take a few days to melt this snowcover, even in the strong March sun, when overnight lows dip enough to refreeze until the pattern moderates after the 24th.

GFS Model Projection for Wed-Thu 3-21,22

In conclusion, consider the following interest groups and impacts which may result from this upcoming weather pattern (extended period of storminess and cold weather)

- If you're a school administrator or department chair, what formal observations planned for the period 16th to 24th? Are these reschedules from earlier weather-related interruptions? Perhaps if you need to fit in an emergency drill or bus evacuation before the month is out, this upcoming week of nice weather might be the opportune time to do it?

- If you're an Athletic Director or Coach, I'm certain you have scrimmages or even early season games scheduled for this time. Realize that this pattern described would most certainly render field use, games and outdoor practices infeasible from Thursday the 15th to Sunday the 24th. What plans or schedule adjustments could be made in the coming week to compensate?

- If you're a landscape or outdoor-related business owner, how might this unwelcome late season weather affect your sales? What will you do to counter a week or more of bad weather when consumers aren't likely to be buying up spring supplies.

- If you work at an Elementary school or daycare center, (both of which I did once long ago), you know the impact to your sanity caused by having to keep the children for indoor recess for an extended period (7-10 days), especially if there's a combination of cold, snow, rain and wind.


- If you're an avid outdoor and gardening person like me, I don't want to see "Breaking News" on CNN: Gardener freezes to death in backyard attempting to keep recently planted bushes alive with body heat. I'm sure Home Depot and Nurseries will be inticing you will all kinds of wonderful things to plant in your yard, but DON'T DO IT THIS WEEK!


When time permits this coming week, I will be adding suporting links within the text, modifying the analysis and including the March 1956 storm analog complete with maps and side-by-side comparison to what's coming. Take advantage of the unique combination this week of more daylight afforded to you by the U.S. Congress, and the brief warm spell provided by Mother Nature. It'll be a nice respite from the recent cold and a promise that help is indeed on the way once we get past this final round of nastiness.

Wednesday, March 7, 2007

LUCKY NUMBER 7 (FOR SOME)

March 7 Clipper O'Luck

CURRENT MID-ATLANTIC RADAR FROM ACCUWEATHER

She was offered Donuts & Hot Chocolate but refused to stop working

Little Miss Foot working diligently to clear the van of the paralyzing .4 inches of snow that gripped the greater Dundalk area on this historic.. okay enough sarcasm. It is a nice little snow though. She was offered donuts and hot chocolate but resisted, saying: "I have to finish first." (Yes, Daddy did also help and not just take pictures.)

In a desperate attempt to corral together some evidence that supports why many schools in the Baltimore Metro area are closed, as well as central Pennsylvania, I have gathered the following from reader input:

1. POLITICS & SAFETY: I was as hugely surprised as the rest of you this morning. I glance out the window at 5:15 and thought.. "Well it did arrive a bit earlier, guess Tom Tasselmeyer won that one." Then I was just stunned to see a region-wide sweep...I mean everyone from Cecil County west and south to Anne Arundel. My only reasonable explanations are:

a) "Reaction" to the February 13 event, where the radar looked very ominous, a Winter Storm Warning was plastered across the region, but the snow started in the 7 o'clock hour. This led to the early dismissal situation later that day. I am curious why so many large districts decided simply to close outright as they did in the February 7 clipper, instead of go with a 2-hour delay, which would definitely allowed road crews time to work and traffic to warm up pavement.

b) This snowfall started earlier, (I'll admit MUCH earlier than I ever expected given low dewpoints), and by 4AM some roads were noticeably slick and hazardous. This was likely the scientific basis for the closing, although I agree with one of our commentors that it would have been possible to navigate in a dusting.

2. SCIENCE: This may still win the day, because despite whatever the pundits say, you're going to see the magic of Climatology and Astronomy today. Today's sun angle is the equivalent of early October, which is to say, quite strong. Luck was a lady last night, as had the snow arrived when I expected it (in the mid-morning) I would not be writing this right now and you'd be at school or work blissfully going about your daily life never fully able to appreciate this sun angle thing. In fact, the sun is poking through our clouds in Dundalk as I write this.

So why did all this happen? My theory is that a couple factors conspired in a short period of time to delivery a second lucky 7th of the month for those of you in school systems.

A) Warm air advection at mid-levels helped moisten the atmosphere at just the right heights to allow dendritic snow growth. This overcame low surface dewpoints.

B) The combination of this moist onshore flow with a rapidly moving clipper into a region where a sharp temperature contrast existed over short distances (upper 20's in DC, lower 50's in extreme southern Virginia) enabled the low pressure to tap some Atlantic moisture in enough time to harness the cold air in the early morning hours, as indicated below:

March 7 Clipper Surface Temperatures

C) Arrival of the Arctic front on Monday sufficiently chilled the ground and atmosphere allowing overnight temperatures to drop low enough over 2 days to enhance the famous "fluff factor" that occurs when a relatively light amounts of moisture are injected into a dry air mass. Liquid-to-snow ratios with this event will probably end up around 15:1 due to this effect.

Indications are a weak coastal Low will form off the Del-Mar-Va, enhancing snowfall this afternoon across the I-95 corridor from DC to Philly, as well as eastern Maryland and Delaware. "Enhancing" meaning if this occurs, it will help to verify the snow advisory call of 1-3" across the central Maryland and Chesapeake Bay region. This is evidenced by recent 3-hour pressure falls as shown below from the UNISYS Weather Analysis site.

March 7 Clipper 3-Hour Pressure Falls

3. HISTORY: If this is any guide, then we are in a geometrically regressing pattern of decreasing snow accumulation closing criteria. February 7 = 2 inches..closed. March 7 = .35 inches..closed. (Granted it is still snowing of course, but just for entertainment purposes, consider this possibility) that the percentage decrease in accumulation from 2/7 to 3/7 is 87%. By that ratio, the next snowfall of .045 inches should be enough to close schools. This analysis is posted for the purpose of demonstrating that I truly do have too much free time and really should move on to making my day more productive from this point forward.

I'm glad that some of us lucked out today. Those of you in the business community of course still have to face the slick roads regardless, so you are no doubt thankful of the favor handed you by the schools. For those in the schoolhouse (whether students, teachers or administrators) hey..take advantage of the time to get caught up, or at least plan on how you're going to catch up in the time that's left between now and Spring Break. I should also warn teachers, athletic directors and coaches that there is a lot of "March Madness" lurking out there in the 15th-20th time frame and it's not looking pretty. More on that later but let say for now I may have to retract my claim of "That's All Folks" from last month.

Speaking of history, this picture is a special message to all those alumni of true snow country... northwest Pennsylvania, western New York, along the Great Lakes and adjacent areas. Mrs. Foot and her family are originally from Crawford County, PA (one step below Erie County...translation: SNOWY!)

Eat Your Heart Out Crawford County!

The point of the picture is to say that not in 100 billion years would you have this type of situation in Crawford County, PA where Mrs. Foot and her brother (who is now in central Pennsylvania) grew up. Whenever we have these crippling snowfalls in the metropolitan areas, my in-laws love to relate the legend of how back on the farm, the snowplow would come charging down the country road early in the morning. Behind the plow was of course, the school bus. The children would board the bus, and then follow the snowplow to school. At end of the day, same process in reverse. The plow would clear a path out to the farms, with the bus trailing behind, and return the children safely. This happened whether was 12", 24" or more. My wife remembers going to school then with 6 and 8 foot drifts either side of the road.

So this morning I went to Mrs. Foot and woke her by saying: "Week 9." In the darkness from under the covers there was a faint, "uuuh?...pause.. 1-hour delay?" I responded, "I wish." She countered with, "2-hour delay?" I answered, "that would be nice." The covers catapulted into the air, light clicked on, and the formally subconscious Mrs. Foot bolted upright to say, eyes wide as the beltway, "CLOSED???" I gave her the coffee, and quietly excused myself from the room with a smile, as I heard in the background..."Oh I have so much to do, how am I going to do the MSA, oh the laundry, I've got to get to school. And there's that IEP..." So Mommy and the bigger of the Little Foots are off to school, and I am managing laundry and the sleeping Littler Foot. oop, just heard a rumbling upstairs. Free time is over.

As you can see, it's tough down here when we've got to deal with .4 inches like this.

Tuesday, March 6, 2007

LUCK BE A LADY TONIGHT?
- Marlon Brando playing Sky Masterson in "Guys and Dolls"

WHAT'S NOT LIKELY TO HAPPEN ON WEDNESDAY: Schools in the eastern Mid-Atlantic (east of the Appalachians) to be delayed, closed or have an early dismissal. (Read: Northern/Central Maryland/Baltimore-DC Metro areas)

Mar clipper

Why? Timing of the storm will be such that accumulating precipitation does not arrive in force until mid to late morning. This precip has to overcome a dry atmosphere and penetrating rays of the sun into the clouds as the snow will be primarily a daytime event. The ground will be cold, however liquid equivalent amounts of perhaps .25 for the entire event will be negated considerably by the aforementioned two factors. I can see a situation where it is snowing to beat the band Wednesday morning into the afternoon, accumulating on cars and grassy surfaces. However roads are simply slick and wet. Daytime traffic helps to warm road surfaces, and combined with salt trucks making rounds, this allows roads to remain perfectly fine into the evening rush, thus eliminating the need for schools to close early on Wednesday. Although it will be super cold out there for most of this week, the sun rays will feel strong...because they are! Intensity of the sun angle now is equivalent to EARLY OCTOBER! This same type of storm in early February if you recall delivered a surprise day off on 2/7 for almost all Baltimore Metro area schools, as cold temperatures caused road surfaces to become very slippery on contact with the snow, and sun angle prevented roads from warming. Not this time my friend. I agree with the National Weather Service on this one..expect a light accumulation not to exceed 2 inches in metro areas east of the mountains. Those of you in the mountains, 2-4 inches seems reasonable. You can also check Accuweather's projections and they are fairly similar. Note to Philly area readers: I think your NWS call is off...2-4 inches is much too high and I doubt the moisture can make it that far east or have enough time to pull in from the ocean before storm departs.

There is the outside possibility that upper level dynamics throw us a curve ball, and enhancement of snow banding due to upward motion (along with higher liquid ratios) as was observed in the February 25 event raised snow totals. Just for fun, I'll explore that possibility tonight...but either way..kids or teachers..you're in school Wednesday regardless.

Thursday, March 1, 2007

MARCH 2007: DEADLIER THAN A LION'S DEN

Alabama Tornado 1

Our hearts are deeply saddened by the sudden and tragic loss of life among students and teachers at Enterprise High School in Alabama. It is a horrific situation, especially for parents, and words cannot describe the soul-wrenching grief which has descended on that sweet little town. Imagine sending your child to school thinking they will be safe, to never see them alive again. I cannot even begin to fathom the horror some of those parents have now faced.

A DEADLY STORM WHICH IMPACTED THE SOUTHEAST AND MIDWEST TODAY IS MOVING INTO THE MID-ATLANTIC AND NORTHEAST TONIGHT. THIS SYSTEM WILL SPAWN SEVERE THUNDERSTORMS, TORRENTIAL RAIN, STRONG GUSTY WINDS AND POSSIBLE TORNADOES THURSDAY NIGHT INTO FRIDAY NIGHT. THE FRIDAY MORNING COMMUTE WILL BE VERY CHALLENGING DUE TO WIND-SWEPT RAIN, LOCALIZED FLOODING, DOWNED TREES AND ISOLATED POWER OUTAGES.

BEFORE YOU RETIRE FOR THE EVENING, PLEASE TAKE A FEW MOMENTS TO CHECK YOUR LOCAL NWS FORECAST AND YOUR CURRENT RADAR FOR POSSIBLE SEVERE THUNDERSTORM/TORNADO WATCHES AND WARNINGS IN YOUR AREA. IF YOUR BASEMENT IS PRONE TO FLOODING, CONSIDER IMPLEMENTING YOUR "PRE-FLOOD" PRECAUTIONS THIS EVENING, AS WELL AS SECURE OUTDOOR ITEMS.

mARCH 1a