Quantitative Precipitation Forecast
Issued by NWS

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000 FOUS30 KWBC 020844 QPFERD EXCESSIVE RAINFALL DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 444 AM EDT WED SEP 02 2015 ...VALID 12Z WED SEP 02 2015 - 12Z THU SEP 03 2015... ...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL... ...UPPER MISSISSIPPI VALLEY... LATEST SATELLITE IR/WV LOOPS SHOW CONTINUED COMPACT MCS DEVELOPMENT ACROSS THE UPPER MS VALLEY...OUT AHEAD OF A WELL-DEFINED SHORTWAVE CURRENTLY PROGRESSING THROUGH EASTERN SD AND NORTHERN NE. THE COMPACT AREA OF UPPER LEVEL FORCING (UPPER DIVERGENCE) IS INTERSECTING A THERMODYNAMICALLY-RICH ENVIRONMENT...WITH MUCAPES ON THE ORDER OF 2000-3000 J/KG...PWS OF 1.5-1.75 INCHES...AND A LOW LEVEL JET PEAKING AROUND 25-35 KTS ABOVE THE DECOUPLED LAYER (~925 MB). THESE PARAMETERS WILL LIKELY MAINTAIN THE CURRENT MCS STRUCTURE THROUGH THE EARLY AM HOURS...WITH THE STRENGTH/DEPTH OF THE INSTABILITY CAPABLE OF INTENSE RAINFALL RATES ON THE ORDER OF 2+ INCHES PER HOUR OVER ISOLATED AREAS PER THE RECENT RADAR ESTIMATES. AS A RESULT...LOCALIZED SHORT TERM RUNOFF ISSUES ARE ANTICIPATED CONSIDERING THE CURRENT FFG VALUES. DO EXPECT A DIMINISHING TREND LATER THIS MORNING FOLLOWING THE DECAY OF THE LOW-LEVEL JET...HOWEVER...THE MODELS (ESPECIALLY THE MESOSCALE GUIDANCE) REMAIN RATHER ROBUST WITH RE-DEVELOPMENT LATER IN THE DAY WITH PEAK HEATING OUT AHEAD OF THE SLOW MCV TRACK...THOUGH BELIEVE THE MAJORITY OF THE GUIDANCE ARE TOO FAR NORTH WITH THE HEAVIER QPF. BASED ON THE CURRENT TRENDS AND ANTICIPATED AREA OF BEST DESTABILIZATION BY AFTERNOON (I.E. LESS MCS DEBRIS TO OVERCOME)... FEEL THE BEST CHANCE FOR LOCALIZED EXCESSIVE RAINFALL WILL BE ACROSS CEN/SRN WI INTO NORTHERN IL. THE ONLY MODEL THAT SEEMS TO BE CAPTURING THIS IDEA AT THIS POINT IS THE 00Z SPCWRF (WHILE KEEPING IN MIND ITS HIGH BIAS). HURLEY $$

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