Tuesday, January 13, 2015

Another Surprise Snow?

COMPUTER MODELS CONTINUE TO SHOW A NORTHWARD SHIFT IN THE PRECIPITATION SHIELD FROM THE CAROLINA COASTAL SYSTEM. MIGHT THE NWS RAISE ADVISORIES FOR DC METRO & OTHER AREAS?
IT'S NOT IMPOSSIBLE. ENTER SURPRISE SNOW #2.


IF THIS TURNS INTO AN UNEXPECTED SNOW EVENT,
AREAS MOST LIKELY TO BE IMPACTED BY 1" OR MORE 
LATE TONIGHT INTO WEDNESDAY MORNING WOULD BE:



  • Washington DC metro area to southern Maryland, including the counties of Prince Georges, Calvert, Calvert 
  • Southern Baltimore metro area including counties of Anne Arundel, Howard
  • Delmarva Peninsula including Dover, Salisbury, Ocean City and VA peninsula communities
  • Eastern North Carolina and Southeast VA


  • 3:10 PM 1/13 - OVERVIEW STATEMENT FROM WINTER STORMCAST TEAM

    We have been tracking an upper level shortwave moving northeast from the Gulf of Mexico, using some "old time techniques" that might be unfamiliar to even today's meteorologists. This approach suggested even yesterday the situation for Wednesday might not turn out as low impact as some currently expect.
    Some computer models and short range maps at the NOAA Weather Prediction Center have been depicting an interaction between this shortwave, energy embedded under the High pressure, and a surface coastal system developing off the Carolinas.

    What is going ON here? We think three factors are in play:
    1) On-shore flow from the Atlantic courtesy of the northern High shown in this map will moisten the eastern Mid-Atlantic tonight into Wednesday.
    2) Influence of the upper level short wave may enhance this moisture and touch off snow in areas that DO NOT AT ALL expect there to be more than flurries. Where? How about DC metro, southern Baltimore and the Chesapeake Bay.
    3) Very cold air at the surface and upper levels would convert this moisture into snow, right quick, with rather high ratios if 5,000 foot temperatures will be between -10 C and -20 C tonight over these regions.

    If you or someone you know is in charge of transportation duties for large organizations in these areas, might want to start checking the National Weather Service forecast in your area -- just so there's no surprises! We will have additional details on this potential system later this evening. 

    Image source: NOAA Weather Prediction Center.
    (If you don't believe what you're seeing above.)

    (Forecasters Foot, Troy A., Connor M., Jason M., Mike N.)


    14 comments:

    Amy said...

    Oh please, oh please, oh please let it be true.

    BioPat said...

    Hmmm, this report is a bit more aggressive than the other reports I am reading but the models are still not in agreement about how far north this may actually move. Well perhaps Foot's Forecasters will call this one "spot on" as they have in past years!

    Morpheus said...

    Advisory posted:
    ...WINTER WEATHER ADVISORY IN EFFECT FROM 4 AM TO NOON EST
    WEDNESDAY...

    THE NATIONAL WEATHER SERVICE IN BALTIMORE MD/WASHINGTON HAS
    ISSUED A WINTER WEATHER ADVISORY FOR SNOW...WHICH IS IN EFFECT
    FROM 4 AM TO NOON EST WEDNESDAY.

    * PRECIPITATION TYPE...SNOW.

    * ACCUMULATIONS...AROUND ONE INCH.

    * TIMING...ONSET AROUND 4 TO 6 AM...CONTINUING INTO THE LATE
    MORNING HOURS...BEFORE MIXING WITH PERIODS OF SLEET AND
    DISSIPATING BY EARLY AFTERNOON.

    * TEMPERATURES...MIDDLE 20S DURING THE PREDAWN HOURS...INCREASING
    TO LOW 30S LATER IN THE MORNING.

    * WINDS...NORTH AT 5 TO 10 MPH.

    * IMPACTS...SNOW WILL LIKELY DEVELOP EARLY IN THE MORNING COMMUTE.
    THIS COUPLED WITH ROAD AND AIR TEMPERATURES WELL BELOW FREEZING
    WILL CAUSE ACCUMULATION OF SNOWFALL ON ROADWAYS. THIS WILL
    RESULT IN HAZARDOUS DRIVING CONDITIONS.

    Instructions: A WINTER WEATHER ADVISORY FOR SNOW MEANS THAT PERIODS OF SNOW WILL CAUSE PRIMARILY TRAVEL DIFFICULTIES. BE PREPARED FOR SNOW COVERED ROADS AND LIMITED VISIBILITIES...AND USE CAUTION WHILE DRIVING.
    Target Area:
    Anne Arundel
    Central and Southeast Howard
    Central and Southeast Montgomery
    Charles
    Northwest Howard
    Northwest Montgomery
    Prince Georges
    Southern Baltimore

    NeedaSnowday said...

    Nothing to see here folks... move along! .oO(1 measly inch?) :::reverse psychology::: ??

    I hate that snowblower still sitting in the box.....ugh!

    BioPat said...

    Needa I still believe you'll be unpacking that snow blower before too long. I, like you, don't get all the fuss about an inch of snow but who knows maybe it will be 2 instead. It will be interesting to see what the schools do with an inch of snow but they are advising folks to leave early or later for work.

    Amy said...

    That weather advisory sounods like the death knell for roads. Last time it started snowing at 5am (oh wait, that was last week) I got stuck in a major traffic cluster as they called school in HoCo at 730. I just really hope to not be stuck on 100 with a screaming baby again.

    Andy, Southern York County Pa said...

    Doesn't take much to destroy a commute around Baltimore. Horrible timing for whatever reaches the ground. A little ice on the road can cause 100's of accidents. This is truly a dusting to an inch snow around Baltimore and south. Horrible timing. Best advice is watch radar trends, dew points, and adjust travel times to avoid the morning rush if needed. An inch of snow in and of itself is not a problem, but the impact it causes is tremendous with accidents etc.

    BioPat said...

    Andy, great to hear from you. I agree the snow itself is not significant but once again it's all about timing. Maryland drivers can't handle rain God bless us in a bit of snow!! Hopefully drivers will heed with caution. The recent mess of the Michigan highways was caused by drives not taking proper care in adverse weather - and they're mush more used to it that we are!

    Westsidehideaway said...

    I will be up early here in West Bmore looking for the inch of snow. I kinda hope it over performs and gives us three or more.

    Morpheus said...

    Westside - It looks like us Bowie and Annapolis Foots followers have a better chance of that with this wee snow maker. It does not hurt to hope for more...

    Andy, Southern York County Pa said...

    This is sneaky. Models keep bumping up qpf. Latest GFS and NAM blend suggest around 2 inches for Baltimore/Washington/Annapolis all the way up to the PA border and into PA.

    Butch Dynomite said...

    Well if B-more struggles with winter weather The kids in Raleigh ought to get a couple of days off......probably pretty tough to get your hands on a carton of eggs an a roll of t.p. about not as well.

    Mike Cheuvront said...

    Life has a way of humbling us over time. Weather is part of our life and certainly tends to keep weather forecasters and us humble here in Maryland. Very sorry for those expecting this to be anything more than a tease. Hang in there. Soon we enter more favorable conditions for powder.

    Foot's Forecast said...

    Thanks everyone for your insightful and engaging participation in what turned out to be, as one of you noted below, just a "tease." That's a great line for what is to come in the 2 weeks ahead, so we will attempt to tease out the details looking down the road.

    (While we learn from the lesson of recent events.)