Quantitative Precipitation Forecast
Issued by NWS

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000 FOUS30 KWBC 281417 QPFERD EXCESSIVE RAINFALL DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1017 AM EDT SAT MAY 28 2016 ...VALID 15Z SAT MAY 28 2016 - 12Z SUN MAY 29 2016... ...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL... SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM 20 S FLO 20 NW SUT 10 WSW SUT 10 S MYR 40 SSW MYR 35 E CHS 10 SSE CHS 20 E NBC HXD 15 W HXD 25 NW NBC 20 S OGB 25 SSE SSC 20 S FLO. 1500 UTC UPDATE SOUTHEAST LA INTO SOUTHWEST MS THE ONLY CHANGE TO THE PREVIOUS EXCESSIVE RAINFALL POTENTIAL OUTLOOK WAS TO ADD A SEE TEXT OVER SOUTHEAST LA/SOUTHWEST MS. SURFACE ANALYSIS THIS MORNING SHOWS AN AREA OF CONVERGENCE OVER SOUTHEAST LA FROM THE OLD OUTFLOW BOUNDARY CAUSED BY YESTERDAY`S CONVECTION. THERE IS MODEL CONSENSUS FOR LOCALLY HEAVY RAINFALL AMOUNTS IN THE VICINITY OF THIS CONVERGENCE AXIS THIS AFTERNOON INTO EARLY EVENING FROM SOUTHWEST MS INTO SOUTHEAST LA. WHILE FFG VALUES ARE CURRENTLY HIGH ACROSS THESE AREAS---SLOW MOVING CELLS COULD PRODUCE SHORT TERM PRECIP TOTALS OF 1-2"+...WITH RUNOFF ISSUES POSSIBLE...ESPECIALLY IN URBANIZED AREAS. PREVIOUS DISCUSSION COASTAL SC/EXTREME SRN NC COAST... THE APPROACH OF TD#2 WILL BRING THREAT OF LOCALLY HEAVY RAINS TO PARTS OF THE SC AND EXTREME SRN NC COAST PRIMARILY LATE SAT AND SAT NIGHT. THIS SYSTEM REMAINS DISORGANIZED BUT IS EMBDD WITHIN A PLUME OF 1.75 TO 2+" PWS. SO LOCALLY HEAVY RAINFALL IS PSBL AS SYSTEM NEARS THE COAST..BUT AS OF NOW...TIMING SUGGESTS AREAL AVG AMOUNTS OF 1 TO 2 INCH CAN BE EXPECTED ALONG THE SC AND SRN NC COASTS BY SUN MRNG. BOTH THE 00Z WRF ARW AND WRF NMM SUGGEST ISOLD AMOUNTS OF AROUND 5 INCHES...THOUGH THE NSSL WRF IS ALIGNED WITH THE SLOWER NAM CONEST IN KEEPING LOWER TOTALS AND THUS WARRANTING ONLY A SLIGHT RISK AT THIS TIME. SEE THE LATEST NHC OUTLOOKS FROM THIS STORM FOR ADDITIONAL INFORMATION. SRN TX... MODELS SHOW RETURN FLOW SURGE DVLPG OVER THE LOWER RIO GRANDE VALLEY SAT/SAT EVENING WHICH COULD SUPPORT SOME INCREASED THREAT OF ORGANIZED CONVECTION..PSBL MCS DEVELOPMENT SAT NIGHT UNDER ANTICYCLONIC UPR FLOW AND WEAK DISTURBANCES LIFTING OUT ACRS NRN MEX. MODEL SPREAD IS MODEST HERE BOTH IN PLACEMENT AND AMOUNTS BUT ALL GENLY TEND TO SUPPORT THE IDEA OF AN ORGANIZED CNVTV THREAT ACRS THIS AREA. WILL CONTINUE TO MONITOR THIS AREA FOR PSBL UPGRADE TO SLIGHT RISK GIVEN LATER DATA TRENDS. SULLIVAN $$

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