Quantitative Precipitation Forecast
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000 FOUS30 KWBC 201849 QPFERD EXCESSIVE RAINFALL DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 248 PM EDT WED AUG 20 2014 ...VALID 18Z WED AUG 20 2014 - 00Z FRI AUG 22 2014... ...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL... SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM 15 N DTL 15 N SAZ ROS RYV 20 ESE GSH 10 S FDY 20 WNW OSU 25 SW TZR 25 SSE ILN 15 SE LUK 30 WNW CVG 25 WNW EYE VYS MXO 20 W MWM 50 NE PIR 35 NE HEI KD50 35 SE CWIK CYBR 15 SW KGAF 15 N DTL. SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM 40 WNW GFL 30 ENE UCA 20 SSE UCA 10 E ITH 10 ENE ELM 25 SSE DSV 15 S DSV 15 WSW DSV 25 WNW DSV 25 WSW ROC 15 WNW ROC 20 SSW CWQP 10 S CYGK 15 SW CWGH 10 S CTCK 15 ESE SLK 40 WNW GFL. NORTHERN PLAINS---UPPER MS VALLEY--MID WEST INTO THE MID TO UPPER OH VALLEY MID TO UPPER LEVEL HEIGHT FALLS EJECTING EAST NORTHEASTWARD FROM THE NORTHERN HIGH PLAINS TONIGHT INTO THE UPPER MS VALLEY DURING THE DAY ON THURSDAY WILL SUPPORT INCREASING CONVECTIVE ACTIVITY FROM THE NORTHERN PLAINS---SOUTHEASTWARD ALONG AND TO THE NORTH OF A WARM FRONTAL BOUNDARY EXTENDING INTO THE UPPER MS VALLEY---MID WEST INTO THE OH VALLEY REGION. PW VALUES AHEAD OF THESE HEIGHT FALLS AND IN THE VICINITY OF THIS FRONT WILL BE RISING TO MUCH ABOVE NORMAL--- 2 TO 2.5+ STANDARD DEVIATIONS ABOVE THE MEAN AS LOW LEVEL SOUTHERLY TO SOUTH WESTERLY FLOW STRENGTHENS INTO THIS BOUNDARY. OVERALL THERE IS FAIRLY GOOD AGREEMENT WITH THE QPF AXES IN THE MODELS. THE 1200 UTC AUG 20 ECMWF DID TREND SOUTHWARD FROM ITS 0000 UTC RUN OVER THE UPPER MS VALLEY AND IS CLOSER NOW TO THE FAVORED AXES OF THE HI RES ARW---NMM AND NSSL WRF WHICH WERE USED PRIMARILY FOR QPF DETAILS. HEAVY TO ISOLATED EXCESSIVE PRECIPITATION TOTALS POSSIBLE IN A NARROW AXIS IN THE VICINITY OF THIS WARM FRONT. THE BIGGEST CONCERNS ARE FOR CHANGES IN THE NARROW QPF AXIS WHICH IS POSSIBLE IF ANY ORGANIZED CONVECTION PUSHES FARTHER TO THE SOUTH AND SOUTHEAST THAN EXPECTED AT THE PRESENT TIME. TRAINING OF CELLS ALONG AND NORTH OF THIS FRONT POSSIBLE--ESPECIALLY EARLY THURSDAY MORNING WHEN THE LOW LEVEL FLOW WILL BECOME MORE WEST SOUTHWESTERLY INTO THE FRONT--WITH ISOLATED SHORT TERM PRECIPITATION TOTALS OF 2"+ POSSIBLE WHERE TRAINING OCCURS. WESTERN TO NORTHERN NEW YORK STATE CONCERNS FOR ISOLATED EXCESSIVE RAINFALL AMOUNTS WILL BE AHEAD OF THE SURFACE FRONTAL BOUNDARY CURRENTLY MOVING THROUGH THE GREAT LAKES THAT IS EXPECTED TO MOVE ONLY SLOWLY EASTWARD THIS PERIOD AS IT ENCOUNTERS BLOCKING FLOW AHEAD OF IT ACROSS SOUTHEAST CANADA. HIGH PW VALUES---1.50-1.75"+--- AHEAD OF THIS SLOW MOVING FRONT WILL SUPPORT HEAVY PRECIPITATION AMOUNTS FROM THE NORTHERN MID ATLANTIC INTO THE SOUTHERN TIER OF NY AND NORTHERN NY. THE SLOW MOVEMENT OF THE FRONT WILL ALSO POSE RUNOFF ISSUES FOR PORTIONS OF WESTERN NY/SOUTHERN TIER OF NY INTO NORTHERN NY WHERE THERE ARE RELATIVELY LOW FFG VALUES. SHORT TERM PRECIPITATION TOTALS OF 1-2"+ POSSIBLE IN AREAS OF SLOW MOVING CONVECTION. ORAVEC $$

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.