Quantitative Precipitation Forecast
Issued by NWS

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000 FOUS30 KWBC 040919 QPFERD EXCESSIVE RAINFALL DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 518 AM EDT WED MAY 04 2016 ...VALID 12Z WED MAY 04 2016 - 12Z THU MAY 05 2016... ...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL... CENTRAL TO SOUTH FLORIDA CONVECTION EXPECTED TO ENHANCE ACROSS CENTRAL TO SOUTH FLORIDA WEDNESDAY ALONG AND AHEAD OF THE SURFACE COLD FRONT FORECAST TO SINK SOUTHEASTWARD ACROSS THE PENINSULA. STRENGTHENING WEST SOUTHWESTERLY LOW LEVEL FLOW OFF OF THE GULF OF MEXICO WILL RAISE PW VALUES TO 2 TO 3 STANDARD DEVIATIONS ABOVE THE MEAN ALONG AND AHEAD OF THE FRONTAL BOUNDARY. THIS ALONG WITH ENHANCED UPPER DIFFLUENCE MOVING ALONG THE FRONTAL BOUNDARY DURING THE FIRST HALF OF THIS FORECAST PERIOD WILL SUPPORT POTENTIAL FOR WIDESPREAD HEAVY RAINFALL AMOUNTS ACROSS THE CENTRAL TO SOUTHERN PORTION OF THE PENINSULA. THERE MAY BE TRAINING OF CELLS IN THE DEEP LAYERED WEST SOUTHWESTERLY FLOW ALONG AND AHEAD OF THE FRONTAL BOUNDARY. WHILE FFG VALUES ARE HIGH ACROSS CENTRAL TO SOUTH FLORIDA---ISOLATED RUNOFF ISSUES ARE POSSIBLE IN URBANIZED AREAS ALONG THE WEST CENTRAL TO SOUTHWEST COAST AND THE EAST CENTRAL TO SOUTHEAST COAST WHERE TRAINING OCCURS. PLEASE SEE WPC MESOSCALE PRECIPITATION DISCUSSION #0176 VALID UNTIL 1320 UTC FOR ADDITIONAL INFORMATION WITH THE CURRENT DEVELOPING CONVECTION OFF THE EASTERN GULF OF MEXICO. CENTRAL APPALACHIANS INTO THE EASTERN UPSLOPE AREAS OF THE CENTRAL APPALACHIANS CONCERNS FOR HEAVY RAINFALL AND ISOLATED RUNOFF ISSUES WILL BE LATE WEDNESDAY AFTERNOON INTO THE EARLY HOURS OF THURSDAY---ACROSS THE CENTRAL APPALACHIANS INTO THE EASTERN UPSLOPE AREAS OF THE CENTRAL APPALACHIANS. SHORTWAVE ENERGY OVER THE UPPER LAKES/UPPER MS VALLEY REGION EXPECTED TO DROP SOUTHEASTWARD THIS PERIOD---AMPLIFYING INTO A CLOSED LOW MOVING ACROSS THE OH VALLEY AND TOWARD THE CENTRAL TO SOUTHERN APPALACHIANS. AHEAD OF THIS CLOSED LOW---THERE IS MODEL CONSENSUS FOR A LEADING AREA OF PRECIP TO DEVELOP IN A SOUTH SOUTHEAST TO NORTH NORTHWEST AXIS FROM NORTHWEST VA---ACROSS EASTERN PORTIONS OF WV INTO FAR WESTERN MD. AT THE MOMENT IT APPEARS THIS AREA OF PRECIP MAY PIVOT IN THIS SAME AREA INTO THE EARLY MORNING HOURS OF THURSDAY AS A NEW COMMA HEAD/DEFORMATION PRECIPITATION BAND FORMS TO THE NORTHEAST OF THE CLOSED LOW. WITH FFG VALUES RELATIVELY LOW ACROSS THESE AREA---ISOLATED RUNOFF ISSUES MAY DEVELOP IN AREAS WHERE THE PRECIP HANGS UP/TRAINS LATE WEDNESDAY AFTERNOON INTO THE EARLY HOURS OF THURSDAY--WITH ISOLATED 2-4"+ TOTALS POSSIBLE. ORAVEC $$

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