271   
FXUS04 KWBC 021903  
QPFPFD  
  
QUANTITATIVE PRECIPITATION FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
302 PM EDT SAT JUN 02 2018  
  
PRELIM DAY 1 QPF DISCUSSION  
VALID JUN 03/0000 UTC THRU JUN 04/0000 UTC  
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR  
  
   
..EASTERN U.S.  
  
A MODERATE RISK FOR FLASH FLOODING REMAINS IN PLACE ACROSS  
PORTIONS OF MARYLAND, DELAWARE AND THE VIRGINAS AS A SHORTWAVE  
TROUGH DRIFTING EAST FROM THE VIRGINIAS INTERACTS WITH A DEEP  
MOISTURE POOL -- SUPPORTING HEAVY RAINS ACROSS THE NORTHERN MID  
ALTANTIC, INCLUDING AREAS THAT WERE IMPACTED BY HEAVY RAINS  
EARLIER IN THE WEEK.  GUIDANCE SHOWS THE AFOREMENTIONED TROUGH  
DRIFTING SLOWLY EAST FROM THE VIRGINIAS TO THE COAST OVER THE NEXT  
24-36 HOURS, WITH DEEP MOISTURE (PWS AROUND 2 INCHES) POOLING NEAR  
THE ASSOCIATED LOW LEVEL CIRCULATION.  EXPANDING COVERAGE OF  
MODERATE TO HEAVY RAINFALL RATES IS EXPECTED TO CONTINUE AS  
INSTABILITY INCREASES THIS AFTERNOON.  WEAK FLOW ALOFT IS EXPECTED  
TO SUPPORT SLOW MOVING CELLS WITH HIGH RH THROUGH THE MID LEVELS  
AND TALL 'SKINNY' CAPE SUPPORTING EFFICIENT RAINFALL PROCESSES.   
THREAT FOR HEAVY RAINFALL RATES IS EXPECTED TO PEAK DURING THE  
AFTERNOON INTO THE EVENING HOURS, WITH A DOWNWARD TREND AS  
INSTABILITY DECREASES OVERNIGHT.  THE RETURN OF DAYTIME HEATING IS  
EXPECTED TO SUPPORT AN UPWARD TREND IN RAINFALL RATES CLOSER THE  
MID ATLANTIC COAST TOMORROW AFTERNOON.  WPC QPF UTILIZED THE HREF  
MEAN AS A STARTING POINT THROUGH MUCH OF THE PERIOD, WITH MODERATE  
TO HEAVY AMOUNTS FROM EASTERN WEST VIRGINIA TO THE MID ATLANTIC  
COAST OVER THE 24-30 HOURS.   
   
..UPPER MIDWEST/GREAT LAKES/OHIO VALLEY  
  
A NEGATIVELY-TILTED UPPER TROUGH WILL CONTINUE TO PUSH SHOWERS AND  
STORMS EASTWARD ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION  
THIS AFTERNOON/EVENING.  THE PROGRESSIVE NATURE OF THE SYSTEM  
ALONG WITH MODEST INSTABILITY SHOULD LIMIT THE POTENTIAL FOR HEAVY  
AMOUNTS, WITH GENERALLY LIGHT TO MODERATE ACCUMULATIONS EXPECTED  
AS THE SYSTEM MOVES ACROSS THE UPPER GREAT LAKES REGION TONIGHT.   
AS THE SYSTEM PUSHES FURTHER EAST ON SUNDAY, INCREASING  
INSTABILITY SUPPORTED BY DAYTIME HEATING IS EXPECTED TO RAISE THE  
THREAT FOR LOCALLY HEAVY RAINS ACROSS THE OHIO VALLEY SUNDAY  
AFTERNOON-EVENING.  THE HREF MEAN WAS UTILIZED AS A STARTING POINT  
WITH A SLIGHT SHIFT TOWARD THE MORE PROGRESSIVE MEMBERS, INCLUDING  
THE HRW-NMMB.   
  
   
..MID AND LOWER MISSISSIPPI VALLEY  
  
DIVERGENT FLOW ALONG OF THE BASE OF THE AFOREMENTIONED TROUGH  
ALONG WITH DEEPENING MOISTURE AHEAD OF THE ASSOCIATED COLD FRONT  
WILL CONTINUE TO SUPPORT DEVELOPING CONVECTION ACROSS FROM THE MID  
MISSISSIPPI VALLEY AND OZARK REGION SOUTHWARD INTO THE LOWER  
MISSISSIPPI VALLEY AND ARKLATEX REGION.    DEEP MOISTURE AND  
INSTABILITY ARE EXPECTED TO SUPPORT LOCALLY HEAVY AMOUNTS WITH THE  
HI-RES MODELS CONTINUING TO SHOW A GOOD SIGNAL FOR HEAVIER AMOUNTS  
CENTERED ACROSS ARKANSAS THIS EVENING.   HOWEVER THESE STORMS  
SHOULD BE FAIRLY PROGRESSIVE IN NATURE, LIMITING THE THREAT FOR  
MORE WIDESPREAD HEAVY AMOUNTS.  THE HREF MEAN WAS UTILIZED AS A  
STARTING POINT, WITH A SLIGHT SHIFT TOWARD THE MORE PROGRESSIVE  
MEMBERS.  
  
   
..SOUTHERN ROCKIES/HIGH PLAINS  
  
GUIDANCE SHOWS A GOOD SIGNAL FOR DEVELOPING PRECIPITATION, WITH  
LOCALLY HEAVY AMOUNTS POSSIBLE ACROSS PORTIONS OF THE REGION  
TOMORROW.  INCREASING SOUTHEASTERLY LOW LEVEL INFLOW AHEAD OF A  
SHORTWAVE TROUGH MOVING ACROSS THE FOUR CORNERS REGION IS EXPECTED  
TO SUPPORT DEVELOPING SHOWERS AND STORMS DURING THE AFTERNOON AND  
EVENING HOURS TOMORROW, WITH SOME SIGNAL FOR MODERATE TO LOCALLY  
HEAVY AMOUNTS ACROSS THE SOUTHERN COLORADO AND THE NEW MEXICO  
RANGES.  
  
PEREIRA  
  
  
 
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