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Excessive Rainfall Discussion
 
(Latest Discussion - Issued 1852Z Aug 30, 2014)
 
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Abbreviations and acronyms used in this product
 
Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
252 PM EDT SAT AUG 30 2014

...VALID 18Z SAT AUG 30 2014 - 00Z MON SEP 01 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 S 9F2 10 S KSPR 15 ENE KVQT 10 NNE KEHC 20 ESE KVBS
20 NE CWF 20 W TVR 35 NNW GWO 20 SE UTA 20 S DYR 35 NNE DYR
15 SSW PAH 20 NE M30 10 WNW HNB 10 NE HNB 25 NW LOU 25 NNW LOU
30 NNE LOU 25 ENE LEX 15 N SME 40 NNE MDQ 30 S 1M4 40 ENE PIB
30 N BIX 20 S 9F2.


LOWER MS VALLEY--PORTIONS OF THE TN VALLEY INTO THE LOWER TO MID
OH VALLEY

THE PREVIOUS SLIGHT RISK ON THE EXCESSIVE RAINFALL POTENTIAL
OUTLOOK WAS EXPANDED NORTHEASTWARD FROM THE LOWER MS VALLEY INTO
PORTIONS OF THE TN VALLEY INTO THE LOWER TO MID OH VALLEY.  AN
AXIS OF MUCH ABOVE AVERAGE PW VALUES WILL CONTINUE TO BE DRAWN
NORTHEASTWARD THIS PERIOD IN THE SOUTHWESTERLY MID TO UPPER LEVEL
FLOW AHEAD OF THE ELONGATED MEAN TROF PUSHING EASTWARD FROM THE MS
VALLEY LATE THIS AFTERNOON.  THE WELL DEFINED SOUTHERN STREAM AREA
OF HEIGHT FALLS COMPRISING THE SOUTHERN PORTION OF THE ELONGATED
TROF WILL BE THE PRIMARY FOCUSING MECHANISM FOR HEAVY RAINFALL
AMOUNTS IN THE ABOVE AVERAGE PW PLUME AS WELL DEFINED UPPER
DIFFLUENCE ENHANCES UVVS AHEAD OF THESE HEIGHT FALLS AS THEY PUSH
NORTHEASTWARD.  THE HI RES ARW--NMM AND CMC GEM WERE USED
PRIMARILY FOR THE QPF AXES-WITH THESE MODELS SLIGHTLY FARTHER
EASTWARD THAN THE REMAINDER OF THE GUIDANCE.  TRAINING OF CELLS IN
A GENERAL SOUTH SOUTHWESTERLY TO NORTH NORTHEASTERLY DIRECTION
LIKELY AHEAD OF THESE HEIGHT FALLS.  IN AREAS OF TRAINING--1-2"+
RAINFALL AMOUNTS IN AN HOUR OR TWO AND ISOLATED TOTALS OF 3-5"+
POSSIBLE.


TEXAS GULF COAST

WHILE SIGNIFICANT HEIGHT FALLS ALONG THE WESTERN TO CENTRAL GULF
COAST ARE EXPECTED TO LIFT NORTHEASTWARD THIS PERIOD--A SEPARATE
MID TO UPPER LEVEL CIRCULATION WILL REMAIN NEARLY STATIONARY OFF
THE LOWER TX COAST THROUGH SATURDAY NIGHT---FORECAST TO DRIFT
WESTWARD AND INLAND DURING THE DAY ON SUNDAY.  LOCALLY VERY HEAVY
RAINS HAVE DEVELOPED IN THE VICINITY OF THIS CIRCULATION OVER THE
PAST FEW DAYS--AFFECTING THE IMMEDIATE COASTAL SECTIONS OF THE
LOWER TO MID TX GULF COAST.  EXPECT THIS POTENTIAL TO CONTINUE
THIS PERIOD---WITH THE BEST CHANCE OF CONVECTIVE ENHANCEMENT IN
THE EARLY MORNING HOURS OF SUNDAY.  VERY HEAVY TO ISOLATED
EXCESSIVE RAINFALL AMOUNTS POSSIBLE ALONG THE LOWER TO MID TX
COASTAL AREAS WITH ISOLATED SHORT TERM PRECIPITATION TOTALS OF
1-3" IN AN HOUR OR TWO.  WHILE FFG VALUES ARE HIGH---RUNOFF
PROBLEMS STILL POSSIBLE FROM INTENSE RAINFALL RATES--ESPECIALLY
OVER MORE URBANIZED REGIONS.

ORAVEC