Saturday, February 18, 2012

"Joshua, what are you doing?"

"Joshua, what are you doing?"
- Professor Falkin in the 1984 film War Games (Youtube clip)

View a water vapor imagery loop from the East Pacific

11:10 AM EST 2/18/12 Intriquing developments overnight in surface and satellite observations across the southern Plains and East Pacific suggest that the potential winter storm outcome in the Mid-Atlantic may be significantly altered by the following factors: 
  • A strong feed of tropical moisture from the East Pacific is fueling heavy rain, flood warnings and severe weather risks in southern Texas;
  • This feed of moisture has produced a large area of expanding precipitation surging north and northeast (NWS regional radar below)
  • The upper level synoptic (or large scale) setup of this event at present bears striking similarities with the January 28-30, 2010 event. 

NWS UPDATES: Several National Weather Service Forecast Offices in the Mid-Atlantic have begun altering their statements with regard to snow potential in that region. When looking at the National Weather Service in Baltimore it stated, "00Z NCEP Guidance Suppressed Precipitation further south...06z then trended somewhat back to the north." We strongly encourage our colleagues in the National Weather Service to closely reexamine their report on the January 2010 eventA detailed report and revised scenarios with snow totals is posted in the Winter Stormcast Zone.

SOUTHEAST TEAM UPDATES: Our seven state forecast team in the Southeast is posting extensive updates every hour in their Facebook pages. You can access their information by liking our Southeast Regional page now. Auto updates containing NWS warnings are also posted in our Southeast Severe page

Think we're hyping it for ratings? Take a look at exactly what we said on January 24, 2010 when the team was quoted as saying "a prolonged period of snow from January 30 to February 10." 

We're not whistling Dixie this time around either. We are observing strong and convincing data that many along the Mid-Atlantic may face a similar surprise to what happen on that fateful Saturday in January. Maybe it's time the Meteorologists out there ask "Joshua" (the computer model) what is he doing?
(Forecasters Foot and Isaacs)

Friday, February 17, 2012

Colder and Snowier?

9:15 PM EST 2/17/12 | Several computer model outputs this afternoon have begun a much colder and more snowy solution for portions of the central and southern Mid-Atlantic Sunday night into Monday. Our team's earlier analyses of a potentially slower moving storm has played out in the current projections for this weekend. 
  • Snow arrival is expected Saturday afternoon in the Mid-Mississippi Valley Saturday afternoon, the southern Ohio Valley Saturday night, in the Blue Ridge Mountains by Sunday morning, and I-95 corridor of Washington to Baltimore, by Sunday evening. 
  • Significant accumulations, generally defined as 4 or more inches in 12 hours, remain possible the areas noted in bright white on the snowfall timing map. This evening our Winter Stormcast Team will begin developing snow amounts for issuance on Saturday.
  • Continue monitoring the National Weather Service for watches which may be issued this evening. Our team is holding a collaboration at 10:00 PM with an update to follow.
Thanks to Forecaster Jason Warren of the Northeast Ohio Zone for producing our snowfall timing maps.
PD III junior?

12:00 PM EST 2/17/12 For those tracking the latest updates on this developing President's Weekend storm, this snowfall probability map from NOAA shows which areas of the Mid-Atlantic have the highest likelihood of 4 or more inches of snow Sunday into Monday. Prior to the snow even occuring, there is increasing risk of severe weather in the Southeast as indicated in Saturday's Outlook from the Storm Prediction Center as shown below. 

Recent computer model runs from the Global Forecast System (GFS) indicate the low pressure system, once it develops over the Southern Plains on Saturday, may position 40 or more miles farther north, and slow in forward speed. This would expand the area of possible severe weather across the Southeast, and is evidence the eventual low may track slower, and stay inland longer. 

Impacts on the "snow" timing: This northern shift would delay the onset of snow in this manner:

  • Southern Appalachians by Sunday morning;
  • Blue Ridge by Sunday afternoon;
  • Mid-Atlantic by Sunday evening. 
Visit our Winter Stormcast Zone for additional analyses.

Forecast Collaborators Jason Isaacs (Metro Atlanta), Advisors Forrest (West Virginia)  Foot and Berk (Baltimore)