Quantitative Precipitation Forecast
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FOUS30 KWBC 231428
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1027 AM EDT TUE MAY 23 2017

...VALID 15Z TUE MAY 23 2017 - 12Z WED MAY 24 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 E KIKT 35 SSW JKA 30 NE BFM 35 WSW MGM ALX 30 NW LGC PDK GVL
35 NE DNN 10 SSW TYS 20 ESE TRI 10 ENE BCB 15 N FVX 15 ESE FYJ
55 NE FFA 35 E HSE 50 SE MRH 60 S SUT 45 SE HXD GNV 70 SW CTY
120 S AAF.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
55 SE KVOA 50 NE KVOA 10 WNW NSE 30 NE GZH 20 NE MXF 15 N LGC
25 SSW WDR AHN 25 WSW CEU 25 SW AVL 15 NNW SVH 20 ENE MTV
25 N AVC 15 SSW FAF 15 ESE 9W7 30 WSW HSE 30 ESE ILM 20 SE CHS
20 NNW BQK 45 WNW VQQ 40 SW 40J 55 SSW AAF.


15 UTC UPDATE...

OVERALL NO LARGE-SCALE CHANGES WERE MADE TO THE PREVIOUS
OUTLOOK...JUST SMALLER ADJUSTMENTS BASED ON RECENT RADAR/SATELLITE
TRENDS AND RECENT RUNS OF THE HI-RES GUIDANCE.  THESE ADJUSTMENTS
INCLUDED A SLIGHT NORTHWARD EXPANSION OF THE OUTLOOK AREAS ACROSS
CENTRAL AL AND NORTHERN/CENTRAL GA.  THE ONGOING HEAVY RAIN THREAT
IS EXPECTED TO CONTINUE THROUGH THE REMAINDER OF THE MORNING INTO
THE AFTERNOON...WITH THE LATEST RUNS OF THE OPERATIONAL AND
EXPERIMENTAL HRRR SHOWING A STRIPE OF MODERATE TO HEAVY
ACCUMULATIONS.  REFER TO WPC MPD #0265 FOR ADDITIONAL DETAILS ON
THIS ONGOING THREAT.  TO THE NORTH...INCLUDED THE REMAINDER OF
CENTRAL NC IN THE SLIGHT RISK AREA.  THE LATEST HI-RES
ENSEMBLES...IN ADDITION TO THE LATEST RUNS OF THE OPERATIONAL AND
EXPERIMENTAL HRRR...SHOW THE POTENTIAL FOR REDEVELOPING MODERATE
TO HEAVY RAINS ACROSS THE REGION LATER TODAY...WITH LOCALLY HEAVY
TO EXCESSIVE ACCUMULATIONS POSSIBLE.


PREVIOUS DISCUSSION...

FL PANHANDLE/NORTH FLORIDA INTO THE SOUTHEAST AND SOUTHERN MID
ATLANTIC

A BROAD MARGINAL AND SLIGHT RISK AREA WAS MAINTAINED IN THE
VICINITY OF THE STATIONARY FRONTAL BOUNDARY FORECAST TO STRETCH
FROM THE CENTRAL GULF COAST---NORTHEASTWARD INTO THE SOUTHEAST AND
SOUTHERN MID ATLANTIC THIS PERIOD.   A WELL DEFINED IMPULSE IN THE
BROAD WEST SOUTHWEST MID TO UPPER LEVEL FLOW DOWNSTREAM OF THE
AMPLIFYING UPPER TROF ACROSS THE PLAINS/MS VALLEY REGION WILL PUSH
THROUGH THE SOUTHEAST INTO THE SOUTHERN MID
ATLANTIC---ACCENTUATING LIFT IN THE VICINITY OF THE FRONT AND THE
ANOMALOUS PW AXIS THAT WILL PERSIST IN THE VICINITY OF THE
BOUNDARY.   THIS WILL SUPPORT A BROAD SWATH OF POTENTIALLY HEAVY
RAINS ACROSS THESE REGIONS THIS PERIOD---WITH POTENTIAL FOR
TRAINING OF CELLS IN WEST SOUTHWEST TO EAST NORTHEASTERLY
DIRECTION PARALLEL TO THE FRONTAL ZONE.  IN AREAS OF
TRAINING---HOURLY RAINFALL TOTALS OF 1-1.5"+ AND TOTALS OF 2-4"+
ARE POSSIBLE.  RECENT VERIFICATION HAS SHOWN A LOT OF MODEL ERROR
IN QPF DETAILS---WITH OFTEN THE BEST PERFORMING GUIDANCE BEING
THESE HI RES ARW AND NMMB MODELS.   THESE MODELS WERE FOLLOWED
MORE CLOSELY THIS PERIOD FOR QPF DETAILS.

PEREIRA/ORAVEC

$$





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