Tuesday, February 11, 2014

"Y'all Ready For This?"



"Y'all Ready For This?"
By 2 Unlimited, 1991 single and Space Jam Soundtrack




11:20 AM EST 2/11 (UPDATE from 5:25 AM - Winter Stormcast Team) If this next storm unfolds as currently projected, we might end up in a real life "SPACE JAM" like we were in February 2010. Details below and a storm timeline map posted later today. 


SYNOPSIS
With 48 hours remaining before a potentially classic "Nor’easter" winter storm is set to impact the region Wednesday night into Thursday, we will begin narrowing our scenarios from the previous post. A storm system from the west will become enhanced by moisture from the Gulf of Mexico. Then the low pressure will track northeastward along the coast. This track is not set in stone, and there is still uncertainty regarding the precise path, the amount of precipitation and to what extent liquid-to-snow ratios will be.

LEFT: Latest precipitation projections show 1.0-2.5 inches of liquid stretch from Louisiana to Maine for the period Tue 2/11 to Sun 2/16, suggesting a possible subtropical moisture feed (known as an "atmospheric river") may be a factor this storm's outcome.





TIMING: For the Mid-Atlantic, start time is expected by Wednesday evening, from south to north. For areas along the I-81 Corridor in Virginia, snow will get underway in daylight hours on Wednesday, and in the Southeast impact are expected Tuesday night.  The storm is expect to depart the coast starting Thursday afternoon. 



PRECIP TYPE: Snow is expected for much of the Mid-Atlantic west of Chesapeake Bay and along the I-95 corridor into Virginia and North Carolina. Precipitation for all these areas could be quite heavy at times Wednesday night into Thursday morning. This projection is a more specific and detailed version of yesterday’s Scenario B, but shifted slightly west as shown on our enclosed map. 

  • With a storm track right along the coast, we are currently thinking that those west of I-95 will see snow as the predominant precipitation type. 
  • Along and east of I-95, we may have some mixed precipitation to deal with, since there is the possibility the storm pushes in warmer air Thursday morning and flips us over to sleet or rain, before going back to snow at the end. 


ACCUMULATION: Based on latest moisture projections from the NOAA Weather Prediction Center and the North America Mesoscale model output for BWI airport as a representative location, and analysis of latest US and other computer models:
  • Liquid for this storm reaches or exceeds 1.0" for much of Maryland, eastern Virginia, the Delmarva, SE Pennsylvania and New Jersey. 
  • With possible liquid-to-snow ratios of 12:1 along and west of I-95, 15:1 for extreme northern MD into southern PA, and lower ratios of 10:1 or less in coastal areas near or along the Atlantic, this storm has the potential to drop well over 8"+ in some areas. 
  • Locations that remain all snow if no mixing of sleet occurs may top 12" or more. 
  • For specific meteorological details on snowfall ideas, you can review the NOAA WPC Heavy Snow Discussion 
IMPACTS: It is critical to note that regardless of precipitation type, wind will be a major factor in this storm. By Thursday morning into the evening, winds may gust near or above 25 mph. If sleet and/or freezing rain are involved in, this combination of heavy wet snow and gusty winds may lead to a new round of significant power outages in areas affected. We urge residents to avoid thinking that "because the storm is changing over the sleet or rain, it must be WEAKENING!" That is NOT true. In fact, you may be at GREATER DANGER if you venture out in those conditions than just all snow.

TEMPS: For much of the Mid-Atlantic, the storm will have a cold start. That is why we think the region will start as all snow. However, the storm does not have access to a feed of Arctic air, so temperatures my actually warm through the event. This  raises the possibility for precipitation to start mixing with sleet in the late AM hours of Thursday.

BUST POTENTIAL  Although this storm is, regarding a spatial scale, one of the largest potential events since 2010, uncertainty in the track could change the outcome drastically like what occurred in the December 25-26, 2010 coastal snowstorm. What first looked like a Christmas Day 6-12" storm in the DC/Baltimore region turned out to be flurries, and Ocean City MD received a surprise 14" of snow.

So with that said, there is always bust potential with any storm forecast:
  • Bust Plan A - (25% Chance): The storm track shifts west of model guidance, and pushes warmer uttemperatures into the I-95 corridor. Thus a longer period of mixed precipitation or even rain could be expected. And the NW suburbs may not even stay as all snow. The axis of heaviest snow would be shifted slightly westward as well. 
  • Bust Plan B – (15% Chance): The storm track shifts east of model guidance. This would bring snow all the way to the coast, but start to cut down on liquid precipitation for the NW suburbs. This would mean no mixing issues, but less precipitation altogether. 
Stay with us through the day for more information as it becomes available, including a preliminary snowfall later today. For now, if you love snow, we hope "y'all are ready for this."

(Forecasters Mike N., Mintong N., Connor M., Julian B., Greg J., Nikki B., Andrew B., and Advisors R. Foot, K. Krichinsky, B. Lear, Dr. Pete W.)


34 comments:

TeriLynn13 said...

Thanks for posting on your website as well as Facebook. For those of us who rely on your forecasts, and can't get to FB at work, this is really helpful.

BioPat said...

So now that we are finally within the 36 hour mark we can take a closer look at expectations from this former Pineapple express" now better referred to as the 600 lb thonged beauty that has become the focus of Andy's affections. Batten down the hatches this is the one we have bee awaiting for a few years. The good news is that it comes near a holiday weekend so we won't lose too many school days thus July 4th lesson plans are off the table for now.

kristia35 said...

NOW I can get excited!

BioPat said...

Still have not seen a snowfall map, perhaps later today. However the adjectives being used to describe the potential amounts should cause panic at the grocery store for sure. The only one not panicked is my husband who informed me this morning he is going to the beach Friday morning - regardless! My response was simply, "stand up and give your brain some air, you've been sitting on it far too long." On second thought perhaps he was thinking of using a dog sled??

Andy, Southern York County Pa said...

NWS BAL/WASH

SIGNIFICANT TO PERHAPS EVEN A CRIPPLING WINTER STORM WILL IMPACT THE
AREA WEDNESDAY NIGHT AND THURSDAY.

HIGH PRESSURE OVER NEW ENGLAND WILL CONTINUE TO FUNNEL COLD AIR INTO
THE AREA. COASTAL LOW PRESSURE JUST OFF THE SOUTHEAST COAST
WEDNESDAY EVENING WILL INTENSIFY AS THE NORTHERN AND SOUTHERN BRANCH
OF THE JET PHASE TOGETHER DURING THIS TIME. WARM AND MOIST AIR WILL
OVERRUN THE LOW-LEVEL COLD AIR IN PLACE...CAUSING SNOW TO BREAK OUT
FROM SOUTH TO NORTH WEDNESDAY EVENING. THE LOW WILL PASS BY TO OUR
EAST LATE WEDNESDAY NIGHT AND THURSDAY. THE UPPER-LEVEL LOW
ASSOCIATED WITH THE COASTAL LOW WILL TRACK THROUGH OUR AREA DURING
THIS TIME. THE FORCING FROM THE UPPER-LEVEL LOW COMBINED WITH
OVERRUNNING AND A STRENGTHENING LOW-LEVEL JET WILL CAUSE MODERATE TOHEAVY PRECIPITATION ACROSS THE AREA. MOST OF THE PRECIPITATION WILLBE IN THE FORM OF SNOW. HOWEVER...THERE MAY BE ENOUGH WARM AIR FORMIXED SNOW AND SLEET NEAR AND EAST OF INTERSTATE 95 WITH EVEN RAINACROSS EXTREME SOUTHERN MARYLAND.

Andy, Southern York County Pa said...

Gulf moisture being tapped in the deep south. Radar returns looking juicy in the gulf. The BEAST is sucking liquid and feasting on copious gulf juice. After binge drinking it is going to roar up the coast to a neighborhood near you.

I won't make any specific "calls" "guesses" or "forecasts" yet. But based on data a "preliminary" expectation of 18 inches is reasonable at this point based upon all reliable data. Let's see if the runs to greatness continue today. If they do, we are about to enter the BLIZZARD of 2014.

Unknown said...

GFS literally has no model support anymore. Definitely been Dr. No this year. I feel like the GFS is that last juror in 12 Angry Men...You know? The bigot who doesn't like snow?

Anonymous said...

Love this white stuff but very concerned it will ruin travel plans to N.H. on Friday! Difficult to decide pack the suitcase and wait OR wait to toss it in and run to airport early Fri. a.m.! Never easy!

Andy, Southern York County Pa said...

Jeremy,

Half of the GFS ensembles show a massive hit. It is the operational GFS versus all other models including half of its ensembles. It still has been slowly trending toward the Euro. We have seen this many times in the past with southern stream coastal lows. It is playing par with this type of storm.

Amy said...

Andy- do you feel like enough media outlets are watching to give enough prep warning? Aaco office of emergency management has given a heads up to its subscribers. But news media seems iffy.

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

Nam shifts a little east any worries andy

Unknown said...

Why worry about one model. None of them knows the exact track anyway. A big storm is coming. There will be a rain/sleet snow line like almost every storm. The majority opinion is west of the bay will be toasted. Being worried about it is not going to change the outcome. Relax and enjoy whatever happens. Joe Bastardi commented on the NAM and feels it was too far west if that helps ease your mind.

ravensbbr said...

Well said, Mike. Ain't nothing anyone can do about it either way...

Nice thing for us highlanders up at our elevation here is we enjoy a vertical R/S line as well as the East/West line...

Andy, Southern York County Pa said...

KYLE, NO

Latest model discussion from WPC:

"...EASTERN U.S. CYCLONE AND WINTER STORM...

PREFERENCE: 00Z ECMWF WITH SFC LOW TRACK ADJUSTED 40 MILES
SOUTH/EAST

DESPITE BOTH NORTHERN AND SOUTHERN STREAM SHORTWAVES HAVING
ENTERED THE NORTH AMERICAN UPPER AIR NETWORK...SOME SIGNIFICANT
MODEL DIFFERENCES REMAIN. WHAT WE DO KNOW WITH CONFIDENCE IS THAT
THIS STORM WILL PRODUCE VERY DISRUPTIVE ACCUMULATIONS OF ICE AND
SNOW OVER A BROAD SWATH AFFECTING THE SOUTHERN U.S. AND THE EAST
COAST STATES. CONCEPTUALLY THE MODELS INDICATE SIMILAR IDEAS TO
ONE ANOTHER...WITH SURFACE LOW DEVELOPMENT STARTING ALONG THE
CENTRAL GULF COAST AROUND 12/12Z AND THE CYCLONE THEN DEEPENING AS
IT TRACKS ACROSS THE FAR SOUTHEAST STATES TOWARD THE OUTER BANKS
IN NORTH CAROLINA AND THEN UP THE EAST COAST.

THE GFS HAD BEEN ONE OF THE WEAKER SOLUTIONS ESPECIALLY WHEN
MEASURED BY THE SURFACE LOW DEPTH AND THE LATE ONSET OF A CLOSED
CIRCULATION AT 500 MB. THE GFS HAS TRENDED STRONGER AT THE
SURFACE...BUT IS STILL SLOW TO CLOSE OFF A LOW AT 500 MB...AND IS
CORRESPONDINGLY FASTER IN ITS FORWARD SPEED. THE ECMWF HAS STRONG
SUPPORT FROM THE 00Z ECMWF ENSEMBLE MEAN AND THE 00Z UKMET RUN
OCCASIONALLY PHASED WITH THE ECMWF...ESPECIALLY ALONG THE MID
ATLANTIC COAST. STILL...IT IS DIFFICULT TO MOVE OUR PREFERENCE
ENTIRELY TOWARD THE ECMWF...DESPITE ITS RELATIVE CONSISTENCY...AS
THERE IS NO PHYSICAL REASON TO EXPECT THAT THE SURFACE CYCLONE
WILL DEFINITELY SPIN UP AS EARLY AND AS SYMMETRICALLY AS IT DOES
IN THE ECMWF SOLUTION. MANY OTHER SOLUTIONS SUCH AS THE
NAM/SREF/GFS/UKMET HAVE INDICATED A MORE ELONGATED LOW EARLY IN
THE PROCESS...STRETCHED OUT ALONG THE PRE-EXISTING FRONTAL ZONE IN
THE SOUTHERN STATES.

ONE WAY TO RESOLVE THESE DIFFERENCES IS TO TAKE THE CHARACTER AND
INTENSITY OF THE ECMWF SOLUTION AND SHIFT IT JUST SLIGHTLY SOUTH
AND EAST TOWARD MORE OF A CONSENSUS TRACK.

THE NAM HAS FALLEN NEAR CONSENSUS ON OCCASION...BUT THE 12Z RUN
DID NOT. IT IS THE FLATTEST MODEL WITH THE SOUTHERN STREAM
SHORTWAVE THAT SPURS THIS DEVELOPMENT OVER THE SOUTHEAST...WHICH
YIELDS A FAST AND WEAK SYSTEM OVERALL. IT IS NOT RECOMMENDED TO
PUT MUCH IF ANY WEIGHT ON THE NAM AFTER DAY 1."

Tina said...

Wow, poor NAM, put in the corner with a dunce's cap on!!

Patricia said...

Space Jam, 2010 seems so long ago. Could you put a link in to perhaps refresh our memories? Was this the snowmageddon? Or was this the snow that we had two storms in one week? (I thought this one was in December)

Thanks

Andy, Southern York County Pa said...

euro came a little west with track, drier and warmer. More of an 8-12 event for the cities with mixing. HPC still thinks it is too far west which would lend to wetter and cooler solution if they are right.

All this will be the difference between a blockbuster storm or just a major storm. This is an interesting system to follow.

BioPat said...

Interesting JB just posted it's tending East. I guess he's sticking with his Canadian model that has been the most accurate this winter. Still over 24 hours until onset so I am sure there are many more twists and turns until it's on us. The winds will be strong so on top of whatever snow/sleet comes down the weight of that with heavy winds is going to be significant. At last post JB expects it to have potential winds of a hurricane (above 74 mph) - YIKES!!

Tina said...

BioPat, I saw JB's post as well... I took it to mean that, "a little closer to the coast" meant the system had shifted a bit to the west, bringing the low in toward the coast.

Anonymous said...

BioPat, JB's post did not suggest hurricane strength winds. His comparison to hurricane strength was referring to the low pressure of 979mb off the east coast. If that verifies there would be string gusty winds.

Andy, Southern York County Pa said...

I think the best approach to take with this is wait and see. Clearly this WILL BE A MAJOR STORM. 8-12 MAJOR, or 12 to 16 plus are the two camps that I am leaning on. Exciting times for true powder hounds.

Gusts to 35mph and hurricane like pressure falls are more likely. That could lead to blizzard conditions. The exact track will dictate MAJOR VS BLOCKBUSTER.

Andy, Southern York County Pa said...

ACCUWEATHER USING THE "B": WORD.

http://www.accuweather.com/en/weather-news/winter-storm-aims-for-northeast-thursday/23156019

BioPat said...

Sorry I just re-read JB's post regarding Cat 2 Hurricane as related to the Low forming; so much for trying to read posts quickly between classes. Never the less there will be significant wind and that's still an issue with wet snow, particularly following an ice storm so closely. In some ways the ice cleared a lot of dead stuff, in other ways it created weaknesses that may give way under the weight of a wet snow and winds. Once again I would simply assume there will be power issues. No matter we are looking at a serious storm ( finally) beginning tomorrow evening. The last post I saw indicated arrival in Balto around 10 pm and continuing through late Thursday. Perhaps those times have been modified, but I would think anything after 6 pm tomorrow is possible.

mayawild said...

I just want to say how totally excited I am to get a little more quality shoveling in this season. Seriously!
BIG Snow Day!!! please!!

Tina said...

Ha BP! When I read what you said about the hurricane winds, I laughed and told my dogs (seriously) "somebody's doing two things at once or is in a BIG hurry."

Have fun with your snow. I just found out we're (DE) under a storm warning now, while you guys are still "watching." But I know who's gonna get walloped and who's not... enjoy!!

BioPat said...

Gov declares "State of Emergency" in Maryland before storm hits Maryland.

Unknown said...

I hope it doesn't snow now just to show how idiotic he is.

Andy, Southern York County Pa said...

Kyle,

I think O'Malley needs to do it. He is advised by mets from the NWS and other government sources. The potential impact of this storm is great so they cannot take chances or a wait and see approach.

Unknown said...

True Andy your right I just don't like him overall sorry

Amy said...

What is your opinion on mixing of precip types and, if yes, duration?

kristia35 said...

Anxiously awaiting here in Perry Hall. Feels like Christmas Eve!

Storm said...

I'm in Hampstead and we usually fill the bathtubs with water and put gallon freezer bags filled with water in the freezer before the storm starts just in case the power goes out....we didn't do that last week and of course we lost power....I think like someone else mentioned trees are already weakened by last week's storm and well I'm not going to get caught with my pants down this time...SO BRING IT!!!

Unknown said...

Winter Stormcast mid-Atlantic has pretty low totals compared to what other sites are saying. It seems like Foots always stays way on the conservative side for these storms.