Sunday, March 1, 2009

Six Years Waiting -OR- FINALLY a Washington D.C. Snowstorm

Finally ... a D.C. area snowstorm ... if this pans out, it should be the biggest snowfall here since Feb. 2003. I hope this isn't a big bust. I don't think it will be. Odd that it should occur on March 1st, the first day of climatological spring, but we'll take it.

Baltimore/Washington NWS Forecast Office main page showing CWA (county warning area) advisories in place for late afternoon and early night, March 1, 2009

Discussion and images taken from Sterling, Va. (LWX) forecast pages. See URL
http://www.erh.noaa.gov/er/lwx/

--Regulus

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD / WASHINGTON DC
311 PM EST SUN MAR 1 2009

.SYNOPSIS...

A POWERFUL COASTAL LOW WILL MOVE UP THE EAST COAST OVERNIGHT ... BRINGING SNOW TO THE AREA. THE ASSOCIATED UPPER LOW WILL ALLOW SNOW SHOWERS TO CONTINUE INTO THE MORNING ... BEFORE MOVING OF TO THE NORTHEAST ... LEAVING WINDY AND COLDER CONDITIONS IN ITS WAKE. HIGH PRESSURE WILL RETURN TO THE REGION TUESDAY THRU THURSDAY. A COLD FRONT WILL APPROACH THE AREA SATURDAY.


District of Columbia weather forecast for the zone I live in.

NEAR TERM /THROUGH TONIGHT/...

AT 3 PM ... MAJOR BAND OF PRECIPITATION ENTERING OUR SOUTHERN CWA. PRECIPITATION WILL BEGIN AS A BRIEF PERIOD OF SLEET ... AND POSSIBLY RAIN ... BUT QUICKLY TRANSITION TO SNOW. THE LEADING EDGE OF THIS BAND SHOULD REACH ALL AREAS OF THE CWA BY 7 PM ... WITH RECIPITATION ONSET AT A 4 PM TO 6 PM FRAME FOR THE URBAN CORRIDOR. TRACK OF THE SURFACE LOW WILL DETERMINE HEAVIEST SNOWFALL AREA. CURRENTLY THE LOW IS CENTERED NEAR CHARLOTTE NORTH CAROLINA. THE LOW SHOULD PUSH NORTHEASTWARD AND OFFSHORE NORTH CAROLINA BY 0Z ... THEN PASS ABOUT 75 KM OFFSHORE VIRGINIA ... REACHING A POINT JUST EAST OF THE DELMARVA PENINSULA BY AROUND 10Z. (GFS) APPEARS TO HAVE THE BEST HANDLE ON THIS TRACK ... AND IT DEPICTS SIGNIFICANT DEFORMATION ZONE INTENSIFYING ROUGHLY 150 KM WEST OF THE CENTER OF THE LOW. SPATIALLY THIS PUTS THE HEAVIEST SNOWFALL BAND NEAR OR JUST EAST OF THE INTERSTATE 95 CORRIDOR. MOST INTENSE SNOW SHOULD OCCUR BETWEEN 8 PM AND 3 AM ... WITH RATES OF UP TO AND EXCEEDING AN INCH PER HOUR AT TIMES. FOR QPF AMOUNTS...STUCK CLOSE TO GFS GUIDANCE...AND USING A 10 TO 1 SNOW RATIO WORKED WELL AS A START FOR ACCUMULATIONS. SNOW AMOUNTS WILL RAPIDLY DECREASE WEST OF THE MAIN DEFORMATION ZONE ... ANY DEVIATION FROM PROJECTED TRACK WILL SIGNIFICANTLY AFFECT SNOW TOTALS.


516PM EST 01 March 2009 base reflectivity radar from Sterling, Va.

.SHORT TERM /MONDAY/...

AFTER THE SURFACE LOW PASSES OUR LATITUDE ... EXPECT A BRIEF LULL IN THE SNOW AROUND SUNRISE ... AS A 700 MB DRY SLOT WORKS IN FROM THE SOUTHWEST. HOWEVER ... THE UPPER LOW WILL PASS DIRECTLY OVERHEAD BETWEEN 6 AM AND 10 AM ... BRINGING ANOTHER ROUND OF LIGHT TO MODERATE SN/SHSN...WITH ACCUMULATION OF ANOTHER INCH OR TWO BEFORE MID MORNING. THEREAFTER...ACCUMULATING SNOWS SHOULD BE DONE. STORM TOTALS SHOULD BE 7 TO 10 INCHES SOUTH AND EAST OF INTERSTATE 95 ... WITH 4 TO 7 INCHES BETWEEN THE INTERSTATE AND THE BLUE RIDGE.

No comments: