Quantitative Precipitation Forecast
Issued by NWS

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639
FOUS30 KWBC 020821
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
420 AM EDT MON MAY 02 2016

...VALID 12Z MON MAY 02 2016 - 12Z TUE MAY 03 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 WNW CBM 10 E JKL 25 E 48I 30 WNW SHD 15 ESE BLF 15 NNE RHP
15 SSE GAD 25 WSW MGM 35 ENE HBG 10 SSW 2GL 20 N KEHC 30 S KXIH
10 WSW LVJ 20 ESE OCH 10 SE BQP 25 WNW CBM.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 ESE KVNP 20 WNW KCRH 25 NNE GLS 25 SW DRI 25 WNW BTR
20 NNE PTN 20 ESE KVNP.



...NWRN GULF COAST TO ERN TN VALLEY...

A QUASI-STATIONARY SURFACE BOUNDARY ALIGNED NE TO SW FROM THE OH
VALLEY TO SERN TX WILL SLOWLY ADVANCE DOWNSTREAM OVER THE NEXT 24
HRS... AS AN UPPER RIDGE EXTENDING INTO THE SOUTHEAST ATTEMPTS TO
HOLD ON DESPITE MULTIPLE ROUNDS OF SHORT WAVE DYNAMICS KNOCKING AT
ITS DOOR. INVOF AND OUT AHEAD OF THIS FRONT A DEEP PLUME OF
ANOMALOUS MOISTURE CONTENT CONTINUES TO SPREAD NORTH AND EAST TO
SETUP A POSSIBLE EXTENDED ZONE OF HEAVY RAINFALL WITH A SLIGHT
OPPORTUNITY FOR EXCESSIVE AMOUNTS FROM ERN TN/SWRN VA/SERN KY AND
SRN WV TO SWRN LA/SERN TX ON MON. THIS IS THE GENERAL ZONE THAT
THE HI-RES ECMWF AND GFS BOTH DEPICT 1 TO 3 INCH AREAL AVG AMOUNTS
WITH LOCALIZED HIGHER NUMBERS. WPC FOLLOWED A SIMILAR TRAJECTORY
WITH THE POTENTIAL HEAVY RAIN AS LIGHT STEERING COMPONENT AND SEMI
QUARTER RING OF FIRE EVOLVES. THESE QPF NUMBERS COULD PRODUCE
LOCALIZED RUNOFF ISSUES... ESPECIALLY INVOF SERN KY/SRN WV AND
SWRN VA WHERE FFG VALUES ARE LOWER.

OF IMMEDIATE AND SHORT TERM CONCERN IS THE LATEST HRRR/ARW RUNS
THAT CONTINUE TO PINPOINT AN ORGANIZED AREA OF CONVECTION EVOLVING
FROM SOUTHEAST TX INTO SWRN LA. THIS IS WHERE A SMALL SCALE
DISTURBANCE GLIDING ALONG THE SUBTROPICAL JET WILL INTERACT WITH A
VAGUE CONVERGENCE AXIS OF DEEP TROPICAL MOISTURE WITH DEWPTS OF 70
DEG OR HIGHER DRIFTING NORTH OVER THE NWRN GULF OF MEXICO. A
POSSIBLE CONVECTIVE COMPLEX OR MULTIPLE ZONES OF HEAVY RAINFALL IS
ANTICIPATED ACROSS THE TWO STATES AND WPC JUST ISSUED MPD 168 FOR
THIS AREA. THIS COMPLEX SHOULD PROPAGATE DOWNSTREAM BUT THE
COMBINATION OF EXTREMELY LOW FFG AND STALLED FRONTAL ZONE OVER
SOUTH TX SUGGESTS EVEN BACK-BUILDING POTENTIAL NEAR THE SWRN
PERIPHERY OF SUCH A FEATURE. THOUGH WPC QPF DOES NOT DEPICT IT
AREAL-WISE... MESO AMOUNTS OF 2-4 INCHES WITH LOCALLY HIGHER
VALUES WILL BE POSSIBLE INVOF VULNERABLE SERN TX/SWRN LA AND WPC
WENT WITH A MDT THREAT FOR EXCESSIVE RAINS.

MUSHER
$$





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