TUE 2-26 10:00 PM. At least your week in the Mid-Atlantic started tranquil, with sunshine and seasonable temperatures on Monday. From here it gets interesting, and much colder. On Tuesday, the vigorous cross-country system that impacted western states Sunday arrives on the East Coast with force. By afternoon, heavy windswept rain overspreads the region, with temperatures rising into the 50's on southeast winds. Overnight into Wednesday, a powerful cold front sweeps to the coast and leftover moisture may briefly change to snow before ending. Noticeable sub-freezing temperatures will arrive behind the front, creating pockets of black ice that could cause some school delays Wednesday morning in Baltimore County's Hereford Zone along with some parts of Frederick, Carroll and Harford Counties. Starting Wednesday, the region spends remainder of the week in January-like conditions, with highs in the mid 30's to near 40. The next chance for precipitation looks to be a clipper on Saturday bringing flurries or light snow.
MAXIMUM PRECIP AMOUNTS: FORECAST 3" along the I-95 corridor from Washington to Philadelphia. 4" in central and southern Maryland, 5" in northern Virginia, western Maryland, the WV panhandle and southeastern PA. My location of Dundalk and the nearest official reporting station, BWI, will be used to grade the prediction. I project BWI will have a total of 3" of snow/frozen precip, and Dundalk, MD will max at 4". These numbers included ice. ACTUAL: Because the original call was for totals to include Wed PM to Fri PM, that includes the clipper snow Wed afternoon. Results are listed as: -Location: Forecast / Clipper amount + 2/22 amount = total / forecast = Departure in % and Final Grade. Source was NWS Public Information Statements from my link pages.
-BWI Airport: 3 / 1.0 + .20 = 1.2 / 3 = 40% E
-DCA Reagan National Airport: 3 / Incomplete no data, assuming it was E
-Martinsburg, WV (Panhandle): 5 / 1.5 + .20 = 1.70 / 5 = 34% E
-PHL Philadelphia Airport: 3 / .2 + 3.2 = 3.5 / 3 = 86 % B (over by 14%)
-Paoli (Southeastern PA): 5 / .5 + 3.5 = 4 / 5 = 80% B
FRI 2-22 4:00 PM. The latest Baltimore NWS forecast indicates that while the storm is not over, we are on the upside and bulk of precip has passed. Intermittent freezing rain and drizzle along with areas of fog throughout the DC and Baltimore regions may hamper the evening commute. As Capital Weather pointed out, when the sun dips, some wet less traveled areas will likely refreeze somewhat. I also am pleased to bring you a new feature and interactive feature discovered on their site. You can active it simply by clicking and scrolling.
THU 9:30 PM. The Winter Storm Warning now in effect until 10 PM FRIDAY for Central and Western Maryland, Northern Virginia and the West Virginia panhandle probably comes as no surprise to those of you who have been following the development of this storm since last Friday. There are no changes to the forecast, because the truth has arrived : A high impact winter storm will affect the entire Northeast region Friday into Saturday, and not a soul on Earth can stop it. View the NWS spread of warnings and advisories to understand the extent of this storm already. As for the current radar, I'm sure you're noticing the "dry slot" of separation between the two storms, but that is simply an indication the two storms will not "phase" or merge together quickly. This allows the energy from both systems to slowly blend, which actually prolonges the event...and the pain for commuters. The alternative is a rapid phasing, a quick accumulation and then out to sea. That is not likely to happen.
STORM SUMMARY AND IMPACTS: An initial 1-3" of snow starting by midnight in the central Mid-Atlantic will be followed by nearly 24 hours of sleet and freezing rain to affect the entire I-95 corridor from Washington to New York City. Interior sections from Pennsylvania to England will see widespread snow possibly exceeding 6 inches. By Friday afternoon, areas affected by ice may come to a virtual standstill, even hampering the ability of emergency and utility workers to reach residents in need. If you have something important to do, get it done on Thursday, because travel on Friday for most of you will be limited to your living room, TV room and the nearest refrigerator (assuming there's power to keep it working!)
SCHOOLS, COLLEGES, OFFICES: Most schools throughout central and western Maryland, northern Virginia, West Virgina will be closed Friday, in addition to a number of colleges as well as many county, state and federal offices. Any activities, meetings or special events planned for Saturday will have to be rescheduled, so make necessary arrangements now. Those who attempt to open or hold an event will face a travel and logistical nightmare. However, conditions will improve behind the storm on Sunday, allowing roads to dry out in time for a regular school day on Monday.
BACKGROUND AND ANALYSIS: (Skip this part if you're not into the meteorology behind the forecast). The green-blue areas on the map below indicate moisture that will by 1AM Friday be running overtop an expansive dome of sub-freezing surface/lower level temperatures. The lines that bend southwest across Virginia indicate cold air damming, a classic setup for sleet and freezing rain, which may initially start as snow. Also note the 0 deg Celsius line at 5,000 feet is deep in southern Virginia, that indicates an extensive southward push of cold air. Warm air advection at or above the 5,000 foot level will intrude later Friday morning, this will be evidenced by snow changing to sleet and then eventually freezing rain by noon. This is well depicted in the NWS forecast for Baltimore as a representative location for the central Mid-Atlantic. Comparing this Wednesday night GFS projection for 1AM Friday to the current radar, it appears the precip is moving in faster than expected, but may result in just slightly higher snow totals if it starts earlier, despite your concern about the "dry slot."
THE MYSTERY OF FREEZING RAIN. Surface temperatures on Friday will start out in the 20's, and then you'll see a quick rise to 30-32 in many areas, followed by a whole day where the temp hovers just around freezing. This is a phenomenon that often occurs with freezing rain, because water turning into ice is actually a CONDENSATION process, which RELEASES heat into the atmosphere. This "latent release of heat" helps keep the temperature just around 32 or 33. But strangely enough, if slight melting begins to occur, EVAPORATION of that water from a solid back to liquid is a COOLING process, which in turn chills the surface layer just enough to stabilize the temperature. So in effect, once a freezing rain regime has setup, it just keeps on going until enough warm air aloft mixes down to the surface and provides enough warming to take the air temperature past 33. Given the depth and coverage of the cold High pressure dome that's now in charge, I doubt we'll see a change to all rain by Friday afternoon as projected by Baltimore's WJZ. It will be fun to see who is right in the end.
IF YOU WANT TO NOWCAST THE STORM, you don't have to wait for me...I recommend monitoring the following sites over the next 48 hours. For up-to-the-minute data on road conditions in MD, check Maryland Roadway Weather, and if you want the latest indications of precipitation type at BWI, this helpful graph from coolwx.com breaks down what may be falling when. A good sense of what's happening with precipitation and storm movement is best seen on AccuWeather's National Radar Loop and Regional Snow-Ice-Rain Radar, and this map of current observations. If you want more detail and like to decode secret messages written in acronyms, then follow the Baltimore/DC NWS Forecast Discussions, updated about 4-6 times per day. Those who seek serious hard core meteorological prognostication should review the HPC Short Range Discussions. (That's short for Hydrometeorological Prediction Center.) For weather analysis and long range entertainment, Henry Margusity's "Meteo Madness" provides a blend of both.
Justin Berk is a TV meteorologist with ABC2 News in Baltimore who operates a very worthy blog I suggest bookmarking, and since I've been a life-long fan of ABC, I can't recommend any other network anyway. For a long range glimpse of what US computer models are projecting for next week, take a peek at the GFS animation on wunderground.com. There's also the NOAA/NWS 5-day map series, and you can even see our future SuperKahuna indicated there starting Wednesday 2-27. Once we get the first Kahuna launched in full (translate: me home Friday for a day off to do the analysis), then I can start to show you data and maps for next weeks potentially major event that could make this upcoming storm look like a flurry!
WHEN? First round arrives Wednesday afternoon in the Baltimore Metro region and may produce up to 2" before departing late evening. Slick roads may cause schools delays Thursday morning. Second round moves in Thursday night and continuing through Saturday morning, total period accumulation for the DC-Baltimore Metro region by Friday morning could near 4" which includes 1/2" or more of sleet/freezing rain.
WORST PART? Well that's hard to say because it ALL looks bad for commuters. Friday morning is likely to be the most difficult travel period of the week.
HOW LONG? Majority of precipitation will exit the region by Saturday afternoon, and may even change to rain Friday afternoon before it does.
WHAT ABOUT SCHOOL? I suspect delays Thursday morning, and many schools closed Friday across the region from Virginia to Maryland to southeastern PA and New Jersey.
QUESTIONS ABOUT THE STORM SITUATION POSED BY READERS
Pardon the anthropomorphism, but I believe the atmosphere is revealing clues to us on what's really going to happen, and I am trying to pin them down. A well-known forecaster at Accuweather made the point earlier today of a striking similarity between what is about to happen and that of the 3 day period prior to the Feb 03 Blizzard (insert reassuring statement here that neither he nor I are forecasting a blizzard). It's quite simple. Friday night into Saturday Feb 14-15, there was front runner clipper that brought 2-4 inches to the central Mid-Atlantic, and was all done Saturday night. Most of the public who were enjoying their President's Weekend weren't paying close attention, and went to bed Sat night thinking that was it. (Including me) The clipper brought in the Arctic High, the moisture gathered from the Gulf Coast and ran right into the High. Sunday morning we awoke to what no one expected: moderate to heavy snow falling in very cold temperatures. The high departed slower than we thought it would, the easterly fetch kept pumping in Atlantic moisture added to the tremendous surge of Gulf moisture already in place, and pow! Two feet later, the rest is history. Now, given that history lesson, look over the storm synopsis from a long time reader, Mr. E.H. of Boston, and let us know what you think.
SYNOPSIS OF WED-FRI STORM IMPACTS ON MID-ATLANTIC AND NORTHEAST submitted by long-time reader E.H. of Boston, MA.
STORM 1: THE MID-WEEK CLIPPER. This first system comes in Wednesday from the Ohio Valley streaking towards Pennsylvania, Maryland and Virginia. Snow will break out from DC to north of Philly as the center of the Low passes over central VA. I would expect a heavier band of snow somewhere from BWI-PHL-SNJ. Overall, I'm thinking a quick hitting 1-3" here with a few 4" amounts embedded outside the cities. A classic 1-4" clipper despite potentially low moisture amounts to start.
Then we watch the developing second system in the southern Gulf States. A southerly flow will try to ride over a fairly substantial cold air damming in place and this will allow for overrunning snows to take the place of the departing clipper snows in the Mid-Atlantic. Some may not even notice the switch from clipper snows to overrunning snows :)
STORM 2A: MID-ATLANTIC OVERRUNNING EVENT. Snow will streak up from Tennessee toward the I-95 corridor Thursday night before turning over to rain Friday in the cities and coastal areas, while staying sleet/freezing rain just northwest of the cities, where some significant icing will take place. Before the changeover, I could still see a couple inches accumulate, bringing an accumulative snowfall from WED-FRI averaging around 3-4"
STORM 2B: INTO THE NORTHEAST (Continuation of STORM 2A, just further north) As the Mid Atlantic's major cities start to transition to rain, we will see NYC and Providence-Boston get into the action. Snow will streak into the region from the southwest as we head into Friday night and Saturday could yield a snowy day. I am not saying heavy snows, but a moderate accumulation, perhaps a 3-6" snowfall for Southern New England with maybe closer to a 4-8" snowfall north of NYC. Not a major event, but a winter event nonetheless as I bask in 60 degree warmth while writing this in Boston.
OVERVIEW: Snow Wed PM in DC-BWI-PHL-SOUTHERN NJ. Heaviest from BWI-PHL. General 1-3", isolated 4". Late Week MESS Mid Atlantic. Snow to Ice to Rain (SE). Light Snow Accumulations Possible. Significant Icing Interior. Northern PA/NY State/New England Snow Friday PM - Saturday. Moderate Accumulations Possible. (Editor's note: Much appreciation to E.H. for putting this together, he and I have seen many a storm go WAY farther north than was orginally projected, so I'm leaving the calls for southern New England there.)
THE ON-AGAIN, OFF-AGAIN STORM IS ON AGAIN
8 AM MON 2/18: Today, I won't argue with anyone who wants to label me a "model hugger" in the sense that it comes across I'm just shifting my positions based on every individual model run. I normally follow the US generated Global Forecast System (GFS) and the European (ECMWF), to get an idea of general trends. Last night both were showing total suppression of precipitation to the Carolinas for Thursday into Friday. A professional meteorologist, Mr TQ, whom occasionally comments here, has helped set me straight that we are indeed dealing with a negative NAO middle to late next week. However, it seemed that the models were also just suppressing the precipitation too far south too quickly. Regardless of what was being projected, I felt the large scale dynamics were (and still are) going to produce an over-running event. Sure enough, that's what the overnight models came out with, as shown below.
SUNDAY 2/17 PM: I am providing the other side of the discussion, in the event this bears out come mid week. Above was the Sunday night GFS projection for Thursday and Friday. As you can plainly see, very little if any precip in the Mid-Atlantic for that period. Except for the yellow mark over Baltimore that'll represent egg on my face if there's no storm. The strong 1040 mb high coming behind the current storm moving through the Great Lakes looks to charge southeast according to many models. (That was the overall thinking Sunday night).
STORM OVERVIEW: This outline will be revised as information and indicators change, but it represents my present thinking for the Mid-Atlantic states for central VA - Maryland - central PA to New Jersey.
WHEN? Arriving in MD and VA Thursday between 3PM and 9PM. Starts light and intermittent, increases in intensity but will alternate between light and heavy due to waves of low pressure moving along a frontal boundary.
HOW LONG? Majority of precipitation will exit the region by Friday night.
WORST PART? Overnight Thursday until Friday afternoon.
HOW MUCH? If precip remains all snow AND if it trends more north than models currently indicate...then 4 or more inches for central/northern Maryland, central/northern Virginia (4 or more in a 12 hours is NWS Criteria for Heavy Snow) If freezing elements mix in, snow amounts will be cut down closer to 2" and sleet/freezing rain could account for at least 1/2"
SCHOOL? Given the current timing ideas, I would project many schools in the affected areas of Maryland and Virginia closed Friday. An earlier arrival time could interfere with Thursday.
Note: Will be adding a revised surface map to show differences in model projections from this past Friday to today, so we have something from which to base our discussions.
NAO Indications prior to February 2003 Blizzard: Although the NAO was slightly NEGATIVE and trending toward neutral, this slight drift occured in the 2 day period just before and THEN during the storm. My theory is that was a major factor which enabled the primary Low and it’s moisture to “over-run” the High toward the Mid-Atlantic. A strong negative trend in the NAO means Arctic air will overwhelm the region and keep storms south or out to sea. PLEASE NOTE I AM NOT SAYING THIS STORM WILL RESEMBLE FEB 03, I am saying the early indicators are somewhat similar to what was seen prior to that storm and I am showing you those for discussion purposes.
Also of note is that the NAO during Winter 2002-03 spent most of the time neutral to negative, but not significantly so. In recent years, very strongly negative NAOs over several weeks correlated to extensive cold periods, and strongly positive NAOs led to unseasonal warmth. You can see from the chart below that this winter we have not even observed a standard deviation beyond 2, and winter for the Mid-Atlantic has been relatively quiet in comparison to years like 02-03 or 05-06.
2. SEA SURFACE TEMPERATURE ANOMALIES: THE CANARY IN THE COALMINE?
3. UPPER-AIR TEMPERATURE PROJECTIONS: COLDER DAYS ARE COMING UP
Below is the 850 millibar GFS Ensemble map for the Northern Hemisphere, produced 2/16 for 2/21. It clearly shows a 4 to 10 C degree negative departure at the boundary layer (5,000 foot level) over the entire Mid-Atlantic and Northeast starting Thursday, indicating that a cold and expansive High will be parked somewhere nearby. What significant is the "ensemble" is not one single computer model but a compilation of all the different algorithmic scenarios that computer has projected, and merged into a single "averaged" solution. If the average solution is noticeably below normal temperatures right at the onset of our storm, then a lot of forecasts for rain could bust big. Just think...if at 5,000 feet above Baltimore next Wednesday night the temp is already 6 to 8 degrees C below normal, if that ends up being around -15 F at those levels, it would favor the development of dentritic snow crystals. Those are the fastest to form with the highest fluff factor, and lead to high accumulation rates as was observed in February 2003. Too soon to say if that would happen, but the temperatures at least look good so far.
THE BLIZZARD OF 2003: 5 YEAR ANNIVERSARY. For a trip down memory lane, review this article in Wikipedia about the Great North American Blizzard of February 2003, which started 5 years ago, right about now. If you have extra time, take a look at this slideshow I have on an old webshots site from the storm, it makes me feel like I'm still there. Enjoy the memories, I wonder when we'll get to make some new ones like this.
FIVE YEARS AGO TODAY...IT ENDED
This will definitely be another "Nowcast" storm so I suggest you bookmark your favorite regional radar, and keep an eye on surface temperatures. My early call for Thursday schools is simple: Widespread 2 hour delays, with careful re-evaluation at 6:45 AM. If snow bands are continuing to redevelop and have overspread the area farther west than anticipated, it is even possible some districts in central and eastern Maryland will be forced to close. The other possibility is that the secondary Low might veer farther east and take the precip with it, shutting off any real chance for snow west of the Bay. Proof of that outcome will be a big dry slot forming where we thought precip would be, if you see that, you're going in on time because the winds will help to dry roads and parking lots before temps dip below freezing. We shall watch what happens with great anticipation, and I hope you'll post your observations into the evening as we see what the players begin to do.
February 12, 2008 10:16 PM
Here's hoping PSU cancels classes tomorrow! 2 of my 4 I would LOVE to miss!!
February 12, 2008 10:46 PM
Still around 30 here in White Marsh, and the precip just keeps coming. What is it about this week?Russ: I hope you don't lose water (or electricity).Maybe tomorrow we'll get that magic day.
February 12, 2008 10:47 PM
AA county Severn at 1130pm - icy as heck!! Our trex deck is a skating rink and all brick and power lines covered . Streets just look wet and we have heard the plows with salt . Hate to say I think it may only be a delay for tomorrow ! Here is to hoping I am wrong !Mr S
February 12, 2008 11:42 PM
ms abbe said...
I've been reading your blog for 3 years now and have also enjoyed it. :) 5:00am and Baltimore County was the first to announce a 2 hour delay! But I hear people sliding around on the roads outside up here in Abingdon. Interesting that even government offices are opening late. Still a possibility for a closing??
February 13, 2008 5:06 AM
Baltimore County closed...back to bed.
February 13, 2008 7:37 AM
Hello, Mr. Foot.I have spent around two years browsing your blog and checking it nearly daily during the winter months, hoping for even the slightest mention of a delay, closing, snow, ice, or anything else in the Baltimore County area that could lead to me sleeping in.I have decided to make use of the time off to sign up and thank you for giving us a knowledgable and concise yet understandable and basic report of what we can expect in terms of weather.I would also like to congratulate you on correctly predicting the closing and delays of many schools in the surrounding regions.I think that is enough of an introduction for now.Incase anybody missed it, Baltimore County and a few others areas decided to close, thankfully.
February 13, 2008 7:44 AM
snow lover said...
mr foot what is up with the snow that is forecasted for tonight.
February 13, 2008 7:44 AM
Mrs. Burke said...
Fantastic, Harford County follow suit with Baltimore. Let's make it like last year, have off tomorrow, and a delay on Friday . . . that would be awesome. Better yet, off on Friday too so I can leave for my president's day vacation to Luray early!!! The trees are looking mighty bogged down with ice here in Nottingham! It looks like it is raining out there. Also - my husband even has a delayed opening this morning. That should tell you something, because JHU APL hasn't done that since this time last year! Happy sleeping late everyone!
February 13, 2008 7:51 AM
Yeah! We closed. Of course the change was made just as I had awakened my high schooler (she would get on the bus @8:30 in a 2 hr delay) I told her to go back to bed - we are closed. she said, "goodnight". It is an icy mess out there. It's 32 degrees right now. The trees and grass are just beautiful. I want to venture out with the camera, but I'm afaid I'll kill myself - plus it's raining hard. Mr. Foot this is a great site. A friend of yours introduced me to this site last year and I've been hooked ever since. This storm is my first comments though. Ok now this day off officially makes Balto Co have 2 days off and 2 hours. But this is built into the calendar. Keep up the good work! I enjoy reading this.
February 13, 2008 8:05 AM
Heya Mr Foot... home safely from ORLANDO, where it was just glorious! And, just like last year... A DAY OFF to rest!! Must be Disney Magic!! :)
February 13, 2008 8:22 AM
Well Mr. Foot, you were right! I didn't expect this. My only comments are that AA County was open on time, but AA Gov Offices are closed and on Liberal Leave. There is the confusion between living in one county and working in another! I was up and dressed, and almost ready to leave when I heard the delay got changed to a closing. Well here's to a shortened work week! See you on Thursday. On a side note, sorry to the student from Calvert Hall, noticed no closing/delay for them.
February 13, 2008 8:27 AM
Mr. Foot said...
How weird is this? Welcome back to the 1960's I guess. Thanks for all the nice remarks. I'm going to put your comments in a little followup post. I have a theory on how this came about, so don't go blaming your county systems for a late call. Check back in a few for a quick post on this up above.Side note: I arrived at my children's daycare at 8:15 and they handed me the phone.. school's closed. My first thought was, "so this is what it was like in the 60's." I have been told all kinds of horror stories of schools being open on time, then suddenly closing when the buses were arriving, and even the reverse of that. In fact a few of you may even know those stories, except for Julee...that would have been before her time, (tee hee hee).
...thus, I don't think it is wishcasting to project the following...
If the question is: "When will Maryland observe the next plowable snowfall?"