Rapid Accumulation Area
Posted by JAC on 2/5/2010, 1:05 pm


MESOSCALE DISCUSSION 0098
  NWS STORM PREDICTION CENTER NORMAN OK
  1045 AM CST FRI FEB 05 2010
 
  AREAS AFFECTED...ERN WV/SRN PA/NRN VA/MD/DE
 
  CONCERNING...HEAVY SNOW
 
  VALID 051645Z - 052045Z
 
  A SIGNIFICANT WINTER STORM CONTINUES TO DEVELOP OVER PORTIONS OF THE
  MID ATLANTIC. SNOWFALL RATES WILL QUICKLY INCREASE FROM 18-00Z WITH
  INCH AN HOUR RATES BECOMING COMMON AND LOCALIZED RATES OF 2 INCHES
  AN HOUR. RATES WILL FURTHER INCREASE BY 00Z...WITH 2-3 INCH AN HOUR
  RATES AND RAPID ACCUMULATIONS THEREAFTER.
 
  DRY LOW LEVELS REFLECTED ON 12Z SOUNDINGS ARE QUICKLY SATURATING
  THIS MORNING...EVIDENCED BY RAPID DEW POINT INCREASES /2-3 DEGREES
  PER HOUR VIA RECENT OBS/ AND TEMPERATURES SLOWLY DECREASING AS
  EVAPORATIVE COOLING COMMENCES. CURRENT VAD WIND PROFILE DATA ACROSS
  THE CAROLINAS/SWRN VA ARE SHOWING INTENSE WARM ADVECTION PROFILES
  WITH VERY STRONG VEERING WINDS WITH HEIGHT...WHICH WILL FURTHER
  SUPPORT DEEP LAYER SATURATION AS SIGNIFICANT MOISTURE /PWATS NEAR
  150 TO 200 PERCENT OF NORMAL PER 12Z RAOBS/ ADVECTS NEWD. WEDGE
  FRONT AND SUBTLE EFFECTS OF THE INITIAL EVAPORATIVE COOLING WILL
  SUPPORT P-TYPE OF ALL SNOW AS TEMPERATURES AT THE SURFACE REMAIN
  SUBFREEZING.
 
  AS THE UPPER LOW CONTINUES TO SHIFT EWD WITH TIME...UPPER DYNAMICS
  WILL BECOME INCREASINGLY FAVORABLE FOR AN INTENSIFICATION IN
  SNOWFALL RATES AS VERTICAL MOTION INCREASES IN CONJUNCTION WITH
  STRONG UPPER DIVERGENCE. LIGHT TO MODERATE SNOW IS ALREADY BEING
  REPORTED...AND WILL LIKELY TRANSITION TO HEAVY SNOW BY AFTERNOON.
 
  HEIGHT FALLS ARE INFLUENCING SURFACE PRESSURE FALLS NEAR ERN KY/WRN
  VA OF 1 MB/HR OR GREATER...AND IN ERN NC NEAR 1.5 MB/HR AS
  CYCLOGENESIS OCCURS. THE PRESSURE GRADIENT WILL CONTINUE TO INCREASE
  THROUGH THE DAY ESPECIALLY IN VA/COASTAL AREAS AS A SURFACE LOW
  QUICKLY DEEPENS AND MOVES UP THE COAST...CAUSING NEAR BLIZZARD-LIKE
  CONDITIONS IN BLOWING SNOW. AS THIS OCCURS...ADDITIONAL ENHANCEMENT
  WILL BE LIKELY ALONG UPSLOPE AREAS OF THE BLUE RIDGE AND APPALACHIAN
  MOUNTAINS...AND ALONG THE IMMEDIATE COAST AS MOISTURE FLUX OCCURS
  OVER THE OCEAN THEN SHIFTS INLAND NEAR THE DC/BALTIMORE METROPLEX IN
  NELY/ELY LOW LEVEL FLOW.
 
  ..HURLBUT.. 02/05/2010
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Major Winter Event: Mid Atlantic & Ohio Valley. Blizzard Warnings Up DE & NJ Coast - JAC, 2/4/2010, 2:29 pm
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