Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 220822
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
421 AM EDT MON MAY 22 2017

...VALID 12Z MON MAY 22 2017 - 12Z TUE MAY 23 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 ESE KBBF 25 W KMIU BKS 35 NNW HBV RND 30 E OCH 20 SW GTR
15 E 8A0 15 ENE FQD 10 NNE CPC 30 WNW CHS 10 NNW VAD 55 SW PAM.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 SSW KBQX NGP CRP 20 NNW ALI 45 WNW VCT 25 S 3T5 10 E CXO
15 NNW JAS 25 NW HEZ 15 SSW TCL 20 NNE ALX 25 E TOI CEW
20 NW KVOA.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
GLS 30 NE EFD 20 WSW ACP 40 S HEZ HBG 40 N MOB 20 NE BFM
35 SSE PQL.


MID TO UPPER TX COAST---CENTRAL GULF COAST/LOWER MS VALLEY INTO
THE SOUTHEAST

THERE WERE ONLY SOME MINOR CHANGES MADE TO THE PREVIOUS EXCESSIVE
RAINFALL POTENTIAL OUTLOOK FOR THE UPCOMING DAY 1 PERIOD FROM THE
MID TO UPPER TX COAST---EASTWARD ACROSS THE LOWER MS
VALLEY/CENTRAL GULF COASTAL REGION AND INTO THE SOUTHEAST. A BROAD
RISK REGION MAINTAINED IN THE VICINITY OF THE SURFACE FRONTAL
BOUNDARY THAT IS EXPECTED TO REMAIN NEARLY STATIONARY THIS
FORECAST FROM SOUTH TX EASTWARD ALONG THE CENTRAL GULF COAST AND
THEN NORTHEASTWARD INTO THE SOUTHEAST/SOUTHERN APPALACHIANS.
WITH PW VALUES EXPECTED TO REMAIN MUCH ABOVE AVERAGE IN THE
VICINITY OF THIS FRONT--1.5 TO 2+ STANDARD DEVIATIONS ABOVE THE
MEAN---AND STRONG LARGE SCALE LIFT ASSOCIATED WITH HEIGHT FALLS
PUSHING EASTWARD IN THE VICINITY OF THIS FRONT FROM SOUTH
TX---ALONG THE GULF COAST AND INTO THE SOUTHEAST---THERE IS A
STRONG MODEL SIGNAL FOR WIDESPREAD HEAVY TO LOCALLY EXCESSIVE
RAINFALL AMOUNTS.  THERE ARE STILL SOME SIGNIFICANT DIFFERENCES
WITH THE MAX QPF AXES AMONG THE MODELS.  THE FARTHER SOUTHWARD
AXES OF THE ARW---NMMB AND THEIR PARALLEL VERSIONS---ALONG WITH
THE NAM CONEST AND CMC GEM WERE PREFERRED OVER THE FARTHER
NORTHWARD GFS AND EC SOLUTIONS.  THE NAM AND GFS HAVE BEEN SHOWING
A SOUTHWARD TREND OVER THE PAST FEW RUNS WITH THEIR MAX QPF
AXIS---TOWARD THE FARTHER SOUTHWARD HI RES RUNS. THE
ECMWF---HOWEVER---HAS SHOWN THE OPPOSITE.  WHILE CONFIDENCE IS NOT
GREAT WITH THE SHORTER TERM DETAILS---EXPECT AN INITIAL AREA OF
HEAVY RAINS TO SPREAD EASTWARD MONDAY MORNING FROM COASTAL TX INTO
THE CENTRAL GULF COAST---PUSHING INTO THE SOUTHEASTERN U.S. LATER
MONDAY INTO MONDAY NIGHT.  IN THE WAKE OF THIS
ACTIVITY---ADDITIONAL CONVECTION MAY FIRE ALONG THE STATIONARY
FRONT FROM COASTAL TX INTO THE CENTRAL GULF COAST.  TRAINING OF
CELLS PARALLEL TO THE FRONT POSSIBLE AS MOIST WEST SOUTHWESTERLY
LOW LEVEL FLOW PERSISTS PARALLEL TO THIS FRONT INTO EARLY TUESDAY.
 WIDESPREAD 1-3" AREAL AVERAGE AMOUNTS DEPICTED DAY 1 ACROSS THESE
AREAS---WITH POTENTIAL FOR MAXIMA OF 5"+ WHERE TRAINING OF CELLS
OCCURS WITH BOTH ROUNDS OF ORGANIZED PRECIP.  SEE WPC`S MESOSCALE
PRECIPITATION DISCUSSION #0258 VALID UNTIL APPROXIMATELY 1400 UTC
FOR ADDITIONAL INFORMATION ON THE DEVELOPING CONVECTION ALONG THE
TX GULF COAST.


ORAVEC

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