Monday, February 16, 2015

Catch me if you can.

"Catch me if you can."
- 2002 film starring Leo Dicaprio and Tom Hanks (Youtube trailer)


8:00 PM EST 2/16 - TEAM STATEMENT FOR SNOWFALL INTO THE OVERNIGHT
  • Although decent bands of snow have set up across the region, uncertainty remains as to if the moisture levels of the system north of DC have enough depth to produce totals at the higher end of current ranges.
  • Latest short range guidance as of 7:45 PM indicate dry air to the north is affecting snowfall rates in some areas of northern and eastern Maryland. In addition, the storm does not appear to be showing any further northward movement. 
  • Extremely fine-grained snow flakes/crystals are developing in a level of the atmosphere where temperatures are between 0 and 5 F. Thus, snow ratios in the Washington DC area are estimated by computer models and visual inspection to be near 20:1, and 15:1 in northern MD. 
  • The Winter Stormcast Team anticipates snowfall totals, with exception of DC metro, will stay at the LOWER end of our forecasted ranges for this event. See below for our earlier snowfall map. 





3:00 PM EST 2/16   SNOW ARRIVING IN DC METRO AND SOUTHERN MARYLAND. Further assessment of observations, short range guidance and ground reports indicates the system so far is on track to perform as expected. Dry air is slowly being eroded as moisture levels increase with the eastward approaching precipitation shield. We do not plan to raise or lower totals at this time. 





11:50 AM 2/16  TEAM STATEMENT ON SNOW TOTALS AND STORM OUTCOMES

We are cognizant that other outlets and forecasters have different snowfall totals than our map below, or are evaluating raising amounts ahead of the storm. We respect their choice to make that decision, but disagree on a different set of scientific grounds. 

Our view: Dry air ahead of the approaching precipitation will take a number of hours to overcome to achieve moistening of "the column." Evidence: Dewpoints in the region still below zero as of 1100 AM per NOAA Storm Prediction Center Mesoscale Analysis.
  • Once this saturation level is reached, upper level and surface conditions can permit snow to reach the ground and not evaporate before doing so. However, a combination of recent surface observations and short range models suggests just light snow to start from Northern Virginia to DC and Baltimore by the PM commute. Heavier snow may not arrive until around 12 AM. 
  • This dry air delay could easily reduce totals to the lower end of our ranges. A 1029 mb High pressure in Eastern North Carolina is also not moving out as quickly as expected.
  • If we choose to adjust totals, we will first collect actual observable changes in ground truth once the system produces snow in our forecasted locations, versus using only model guidance. Based on the latest guidance, it is more likely we would hold or lower, not raise expected totals.

9:30 AM EST 2/16 - TEAM STATEMENT ON MONDAY-TUESDAY MID-ATLANTIC WINTER STORM 

It seems that storms this winter in the Mid-Atlantic this has been taking a page from the script written by Frank Abagnale Jr. If you know the incredible story, it recounts the travels of the deceivingly charming but elusive teenager whom outwitted federal officials for years while on a check-kiting scheme across the country. 
But similar to what's next for the Mid-Atlantic, reality (and the FBI) eventually caught up with Frank. The question is, will this storm dash away our hopes of one big snow like the clever thief, or will it give in at the last minute and deliver its secrets for all to see?

Summary of our projections:
  • We project a 70% probability of a significant winter storm, with snowfall exceeding 4" in most locations south of the PA/MD line as indicated in our final map below.
  • The bust scenarios below account for the 30% probability of a surprise and drastic change in the outcome

SYNOPSIS A storm system currently strengthening over the southern Plains will move into the Southeast tonight, and off the Carolina coast by Tuesday morning. 
  • With extremely cold temperatures entrenched over the Mid-Atlantic, this will be a rare all snow event. Temperatures will range from the lower teens in central PA to the mid 20s in southern VA during the storm. 
  • The precise track of this storm will result in a narrow band of significant snow accumulation, reaching some of the largest this winter season.


TIMING Snowfall will begin Monday late afternoon during the evening rush hour for the metros of the Mid-Atlantic. 
  • Snow will move in from west to east. The heaviest snowfall is expected from around 10PM Monday night until 3AM Tuesday morning, before starting to weaken and taper off during Tuesday's morning rush hour.
  • Some wrap-around enhancement can not be ruled out, hence why the NWS has warnings effective to 12 Noon Tuesday.

IMPACTS We are looking at a moderate to high impact event in which all snow that falls will stick. Road conditions will deteriorate Monday evening, become very hazardous Monday night, before improving during the day on Tuesday. Tuesday's temperatures still will only reach the upper 20s. This snow is expected to be of the light and powdery variety, rather than heavy, wet snow.
  • Central Maryland: 4-8" between DC and Baltimore, 3-6" north of Baltimore.
  • Southern MD: 4-8" near DC, 6-10" south.
  • Northern VA: 4-8", Central VA: 6-10"
  • Lower Eastern Shore: 6-10", Upper Eastern Shore: 4-8"
  • I-95 Corridor in DE/NJ: 3-6"
  • Southern Pennsylvania: 2-4"

  • WINTER STORM WARNINGS are in effect fo the areas noted in DARK PINK on the enclosed NWS Advisory Map. Visit the Eastern Regional HQ of the NWS to link to your area's local forecast office for current statements.
  • WIND CHILL WARNINGS and WIND CHILL ADVISORIES expire this morning in Maryland as the brutal cold finally starts to loosen its grip, but will continue longer in PA and points north

BUST SCENARIOS - As always we like to stay one step ahead of Murphy's Law and let you know in advance how this forecast could go wrong. The above scenario is what we believe is "most probable". But there are some things that could emerge throughout the day Monday that may impact our forecast.

  • The Big Bachata (10% Chance): How will a MD snowstorm figure out how not to snow? There is a chance the storm has trouble overcoming extremely dry air in place over the region currently. Dew point temperatures are well below 0ºF, and the storm will need to moisten the column of air before snow reaches the ground. It is possible, that dry air sucks some of the liquid out of this system and "wastes" a lot of the snow, leaving those north of Baltimore with 1-3", 2-5" falling in between Baltimore and DC, and 3-6" for southern MD.
  • The Big Kahuna (20% Chance): As this storm develops offshore, it could also draw in additional moisture as it rapidly strengthens. This would create heavy bands of snow sliding across the Mid-Atlantic and surpassing our expected totals similar to what we saw almost exactly a year ago in February 2014 and on St. Patrick's Day 2014. Widespread amounts of 8-10" could show up between DC and Baltimore with 6-8" north of the city, and some areas in southern Maryland getting up to a foot of snow.
That being said, we do think the scenario outlined in the map is most likely. But since meteorology is not an exact science, it is important to express the uncertainty when it is present.


LAST PLAY OF WINTER? Spring-a-lings might want to stop reading here. Unfortunately the answer is no. A third round of brutal, arctic air is looking increasingly likely for Wednesday-Friday of this week. We will have more on this later, but it is looking possible that the temperatures may rival what we say yesterday and today. The second half of February is making up for lost time this season. Will there be better times in March ahead? Stay tuned for our long range look coming in the next several days.


Winter Stormcast Team: Forecasters Mike N., Connor M., Jason M., Mintong N., Troy A., Jolene W., Advisors Keith K., Dr. Pete W.,  and R. Foot

69 comments:

Westsidehideaway said...

Thanks Team! Something to look forward to today. Not a question of if, but rather how much snow is awesome.

Morpheus said...

Being just south of 50, near DC...I might just catch the heavy snow this time if this go as projected. Since last year we did not break 4 inches of snow in our biggest almost all rain winter last year, I am psyched to be near the bulls eye. Let hear it lowlanders this one is for you! (he says with trepidation that it will go out to sea or get sucked up by an alien space craft or blown off course by a volcano or some other unlikely thing ;-))

Amy said...

Pretty sure my heart pump is being for mercy and Thursday looks to be even worse. BGE will be ugly this month.

Timing seems to be a little vague. NWS indicates snow starts around 3pm. Seems a bit early. Others say 6ish. At which point should we stay off the roads?

Unknown said...

No whammy no whammy no whammy.

Amy said...

Ha, no heart pump, but I do have a heat pump.

kyleZ said...

Have a feeling there is to much dry air it's still seven degrees looks like a vigra snowstorm for a while.

Butch Dynomite said...

I have personally seen a lot if bachatta in parkville this season with the radar showing greenblue and nothing in the air ...I have a sinking skepticism that this storm will underperform without coastal development...agree with Kyle

kyleZ said...

I could be wrong but I'm losing optimism fast the dew point is -8 and the storm is going south of us but we've been surprised before I guess.

Morpheus said...

Nope - not going pessimistic, sticking with guidance below (And Andy's 6-10 inches):

Event: Winter Storm Warning
Alert: ...WINTER STORM WARNING REMAINS IN EFFECT FROM 6 PM THIS EVENING
TO NOON EST TUESDAY...

...WIND CHILL ADVISORY IS CANCELLED...

* PRECIPITATION TYPE...SNOW.

* ACCUMULATIONS...6 TO 10 INCHES.

* TIMING...SNOW IS EXPECTED TO DEVELOP EARLY THIS EVENING AND
CONTINUE INTO TUESDAY MORNING. HEAVIEST SNOWFALL IS EXPECTED
THROUGH TONIGHT.

* TEMPERATURES...LOWER TEENS TO LOWER 20S.

* WINDS...EAST 5 TO 10 MPH.

* IMPACTS...BEGINNING THIS EVENING...ROADS WILL BECOME SNOW
COVERED AND SLIPPERY WITH VISIBILITIES BEING REDUCED TO ONE HALF
MILE OR LESS AT TIMES. THE COMBINATION OF SNOW COVERED ROADS AND
LOW VISIBILITY WILL MAKE TRAVELING DANGEROUS.

Instructions: A WINTER STORM WARNING FOR HEAVY SNOW MEANS SEVERE WINTER WEATHER CONDITIONS ARE EXPECTED OR OCCURRING. SIGNIFICANT AMOUNTS OF SNOW ARE FORECAST THAT WILL MAKE TRAVEL DANGEROUS. ONLY TRAVEL IN AN EMERGENCY. IF YOU MUST TRAVEL...KEEP AN EXTRA FLASHLIGHT... FOOD...AND WATER IN YOUR VEHICLE IN CASE OF AN EMERGENCY.
Target Area:
Anne Arundel
Calvert
Central and Southeast Howard
Central and Southeast Montgomery
Charles
Prince Georges
St. Marys

Morpheus said...

NWS Warning from 9:50 EST.

Syracuse1 said...

Let it SNOW!!

Anonymous said...

Bernie Rayno has the storm trending north as well. Guess we'll have to wait and see!

Mr. Foot said...

The team saw various reports from outlets including TWC, DC Mets and others not to be mentioned that were raising, or considering raising, totals for DC and Baltimore. We see the dewpoint issues you all do and the team wanted to make it more clear why we are not making changes at this time.

genser95 said...

There really hasn't been any "trending" at all in the last 24 hours. Sure, by a few miles here or there, but nothing to write home about. It will be interesting to see the ratios; it rarely snows heavily down here at these kinds of temperatures.

Westsidehideaway said...

Just back from the grocery and the world is expecting A LOT of snow based on the craziness there. I agree that it is awfully dry and this could effect snow totals. Let's hope it trends a little north and brings more moisture.

ravensbbr said...

Just to break up the (non)action so far...

...watch Jim Cantore lose his stuff over thundersnow...

https://www.youtube.com/watch?v=PdRWGMyeSYY

...also, his reaction times are terrible...flash...stands there...then starts crowing as if he threw the switch himself...LOL... #mainstreamweatherpukes

Westsidehideaway said...

Radar shows just how big this storm really is. This is just my observation and not based on anything other than that, but looking at the radar also makes me believe that it will trend farther north than expected. Thus bringing more moisture to Bmore. We shall see. Should be fun!!

ravensbbr said...

Like how you think, Westy! :)

kyleZ said...

Andys 6-10 would be great and I hope it verifies and we all enjoy a snow day tomorrow.

BioPat said...

Agreed Westie! I just got back from OC, clouds are getting low and dark. my only concern is the lack of mositure, but this storm is big enough to provide lost of juice. Now to decide do I trek up the beltway for class this afternoon and risk a mess heading home at 7 pm.

Westsidehideaway said...

Hi Bio. My wife works for a local U and they are closing shop at 6 tonight. Might want to check before heading to class. Anyone seeing any flurries out there?

BioPat said...

Thanks Westie. I have been checking but Goucher is known for staying open until the last minute. I have to make a decision in the next 10 minutes as class begins at 5

NeedaSnowday said...

BP... IIRC you are taking classes at Goucher? I am quite close and we got nada right now! Hopefully the college will make an early decision... Much like I hope school systems will do!

Morpheus said...

BP -Towson University is closing at 6 pm tonight, I would not be surprised if they closed early.

Morpheus said...

Flurries starting just south and west of Bowie, MD...an hour before the WSW. Good sigh I think, getting past the dry air.

Westsidehideaway said...

I just checked out some webcams around DC and it is snowing in College Park. Nothing yet here on the Westside of Bmore.

Westsidehideaway said...
This comment has been removed by the author.
Flame said...

Reports of snow falling in Columbia and Greenbelt since 4-4:15 PM. Won't be long before virga gives way to snow. Snow looks very fine.

Amy said...

Starting in pasadena. Very small flakes, but they're here!

Amy said...

Starting in pasadena. Very small flakes, but they're here!

Unknown said...

Light snow showers in Annapolis

Morpheus said...

Drive way coated, along with cars. Good start. Move the cars to make the most of the new plow for my ATV...should be more fun than running a snow blower.... ;-)

Westsidehideaway said...

It's 5:05 in West Baltimore City and two things are official at this hour. It is lightly snowing and it's Happy Hour!!

Butch Dynomite said...

Good idea! Westside....cheers....but no snow in Parkville yet

Westsidehideaway said...

Thanks Butch. Don't worry. It's coming.

Westsidehideaway said...

TomTasselmeyer is now saying the Bmore should really be in the Advisory area and not the Warning area and we will only get 2-4 inches in the City. Is he looking at the same radar that I am? Wonder what gives here?

Morpheus said...

To a more trained eye - is it tracking further south? Looks good to me. Happy hour sounds good and well see how things look when the heavy stuff arrives later tonight...

Morpheus said...

Steady light snow - street starting to get coated. Picked up all the sticks for better sledding tomorrow on the hill out back.

Westsidehideaway said...

Hey Morph. I picked up the sticks today and they are headed for the fireplace tonight. Hoping the Foots team weighs in soon on the total predictions.

Unknown said...

Just home. Traveled from Park Hgts Ave & Caves Valley. Very light snow during trip. Here at home, cars have light covering.

Morpheus said...

Westside - with this cold my wood stove is going non-stop. Almost did not buy this house because it has a heatless pump. I have lot's o-trees so branches I have in abundance an too many gum balls to try and keep out of the lawn. Steady light snow...going to start dinner.

Westsidehideaway said...

Morph. Hope you have a good meal. Still light but steady snow here. City trucks have been through so the roads look okay. Everything else has a quarter inch of powder.

BioPat said...

Just got back from Goucher. Beltway was ok, lots of trucks doing nothing. Too cold for chemical treatment so they'll have to wait to plow. The college finally decided to close at 6:30 we dismissed 15 minutes early. Now, if this does materialize into something significant perhaps tomorrow evening will be an online class.

Amy said...

HoCo is officially closed tomorrow :-)

Matt said...

It's been snowing for about 2 hours here on the PG/AA line, and accumulation is well under an inch. Unless this thing gets going (and soon), I'm thinking the lower amounts predicted by FF are going to win out. Which, you know, sucks for me and my handle of whiskey.

Unknown said...

Artic high sucking the moisture out like a dehumidifyer is the reason for low rates so far. Winds need to turn more east and northeast to begin saturating air with more ocean moisture. I am toast here in CC. Its 9 degrees.

Anonymous said...

Expectations aside, Baltimore County is already closed tomorrow. Better safe than sorry I suppose.

Julee said...

1/2 inch of diamond dust in Pikesville.

Anonymous said...

Add the city to that list.

Unknown said...
This comment has been removed by the author.
Flame said...

I find it amusing that it was too warm in the past storms...now it's too cold and too dry. Snow looks very dusty here just northeast of DC. So pretty much, unless we get more moisture in (which might happen overnight) we are looking at a very different kind of dance. Dancing with wolves?

Butch Dynomite said...

Preemptive cancellations not the worst idea imo but yeah ....need something to change if you guys think about getting out the blowers....just going by the texts from my friends: Baltimore county probably needed at least a 2hour hangover delay

kyleZ said...

I'm done with this winter in harford county it's either north south east or west and also to dry or 34 and rain and we always have a dry slot we just can't win

Morpheus said...

Westside Dinner was good and just finished helping my son with school project. Flakes are getting bigger, still falling gently but definitely picking up. There is about 2 inches down.

Kyle Z. - I feel your pain, last year all I got was rain while everyone else north of 50 were getting snow. The Irony is I might be to north for the direct hit, just hoping for enough to sled on tomorrow. 6 inches will do. Since most of the heavy snow was not predicted until after midnight I think we may have a shot.

kyleZ said...

Well I guess I can't complain then Morpheus we had close to 70 inches last winter. Enjoy the snow!!!!!

Morpheus said...

Kyle I do not mind if you complain - I did lots last year, surprised I was not kicked off the blog island. A ral nice super narrow east to west band came through that look like it was neighborhood wide that went right over my house - I picked up a little over a half inch in a half hour. W are pushing close to three inches, It has slowed though and it look like I have a pause small dry slot at the moment. This storm is still picking up moisture over Texas and Some of it looks to be forming north of the main storm...some hope maybe?

Butch Dynomite said...

One good thing about this blog is if I dont get hit I am still rooting for one of y'all, still ....feel we have all been dealt rags this season even suprisingly the highlanders

Butch Dynomite said...

One good thing about this blog is if I dont get hit I am still rooting for one of y'all, still ....feel we have all been dealt rags this season even suprisingly the highlanders

kyleZ said...

Yea I really hope this dry slot fills in so someone atleast gets a good dosage of pixie dust.

kyleZ said...

Looks like a band from dc to pa line filled back in but doesn't look like behind it in western va/md maybe the mountains playing tricks with the radar or they are taking all the moisture.

Unknown said...

Looks like about 4 inches here in Southern Calvert County.

Morpheus said...

Anthony look like you have a lot more coming your way!

Butch Dynomite said...

Even if it's not a kahhhuna ...here's to nowcastiing

Morpheus said...

Butch you said it! but I fell asleep on the couch so I was Z-casting! coming down at a good clip. I have maybe 4 inches and it looks like I might just be riding the edge...good luck all (but especially fellow lowlanders - enjoy! going to bed.

Andy, Southern York County Pa said...

The storm moved a little faster than anticipated and the snow to liquid ratios that normally are associated with extreme cold that we are experiencing did not verify. Ratios initially were 10:1 to 12:1. Seems most had 3 to 4 inch totals with some isolated 5 totals. We had 3 up here and more importantly everything that counts is shut down in Baltmore! I have my first snow day so while a bust in numbers I will call it a win for impact and timing. Enjoy the snow day!

Morpheus said...

Looking out on the table on the porch, restocking the wood stove at the moment, looks like we have between 5 and 6 inches. Despite ratios not verifying Andy I consider the foots team and your forecast to have just verified here on the low end. I am thrilled to have this amount of snow for a week or two on the ground...it will feel like winter both visually and temp. wise. Oh yeah Towson University is open at Noon...So no day off.


Unknown said...

I guess if the goal for most is a day off then most people won. I do not win unless there is at least a foot on the ground so I am at work.

If Foots is right about an abrupt end to winter, this MAY have been our biggest storm which would be a shame.

You Just don't know what to believe because the euro temperature outlook for March was for below normal temps in the East??

So early spring or more chances at powder? Who knows?

kyleZ said...

We had four inches of pixie dust in harford just wish it would have slowed down to dump but on to the next one I guess.

kyleZ said...

Does this next arctic look as potent as the last one?The cold looks nasty on Thursday and Friday with possibly two sub zero nights and the Nws has a 50 percent chance of snow Wednesday for most in Maryland and 1-2 inches in southern pa.