Quantitative Precipitation Forecast
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FOUS30 KWBC 270038
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
837 PM EDT WED APR 26 2017

...VALID 01Z THU APR 27 2017 - 12Z THU APR 27 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 NE AAA 10 SW IGQ 10 WNW VPZ 10 N ASW 10 SSE OKK 25 SSW BMG
30 WSW HOP 10 SSE TUP 45 NW MEI 30 SSW HKS 30 ENE HEZ 25 S ESF
15 NNE ESF 30 E MLU GLH 40 SW UTA 10 SE M19 15 NNE ARG
20 NNE FAM 10 ENE ALN 15 NE AAA.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 NW NQA MDH ENL 10 NW MTO 15 SSE CMI LAF 15 ESE HUF EVV
45 NNE MKL 35 SSW MKL 25 SSE OLV 25 ESE UTA M97 25 NW NQA.


0100 UTC UPDATE

CHANGES TO THE PREVIOUS EXCESSIVE RAINFALL POTENTIAL OUTLOOK WERE
TO REMOVE MARGINAL RISK AREA ACROSS SOUTHERN MAINE WITH ADDITIONAL
RAINFALL AMOUNTS OVERNIGHT EXPECTED TO BE GENERALLY LIGHT.


FROM THE MIDWEST TO THE LOWER MS VALLEY...HAVE TRIMMED BOTH SLIGHT
AND MARGINAL RISK AREAS WITH CONTINUED PROGRESSION OF SQUALL LINE
ACROSS THE AREA AS ASSOCD UPPER TROF BEGINS TO TAKE ON A MORE
NEGATIVE TILT.  AS THE UPR TROF BEGINS TO LIFT NEWD THIS EVENING
ACROSS THE MID MS VALLEY...WE SHOULD SEE AN ACCELERATION OF THE
SOUTHERN PORTION OF THE ASSOCD COLD FRONT AND PREFRONTAL SQUALL
LINE.  HOURLY RAINFALL RATES COULD APPROACH OR LOCALLY EXCEED AN
INCH FROM MS SOUTHWARD INTO LA..BUT STORM TOTAL AMOUNTS ARE NOT
LIKELY TO EXCEED MORE THAN 2 INCHES GIVEN THE EXPECTED
ACCELERATION OF THE LINE AND THESE AMOUNTS WILL REMAIN WELL BELOW
EXISTING FLASH FLOOD GUIDANCE VALUES.  FARTHER NORTH..HAVE
MAINTAINED A SLIGHT RISK FOR THE EARLY PART OF THE OVERNIGHT PD
WITH WIDER SWATH OF MDT TO LOCALLY HEAVY CONVECTIVE RAINS EXPECTED
FROM WRN TN NWD INTO WRN INDIANA WITH INCREASING UPPER DIFFLUENCE
AHEAD OF THE NEG TILTED UPPER TROF.  THE INCREASING MID/UPR
FORCING COINCIDENT WITH AXIS OF 500 TO 1000 J/KG MUCAPES AND
GREATER THAN 1.5 INCH PWS..COULD SUPPORT LOCAL 2"+ RAINS IN A FEW
HOURS WHICH WOULD APPROACH OR LOCALLY EXCEED SOME OF THE LOWER FFG
VALUES ACRS THIS REGION.

SULLIVAN
$$




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