Quantitative Precipitation Forecast
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FOUS30 KWBC 180829
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
428 AM EDT TUE APR 18 2017

...VALID 12Z TUE APR 18 2017 - 12Z WED APR 19 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 W KVAF 50 ESE KMIU 15 ESE KOPM 35 ESE BKS 20 S NQI 15 N CRP
45 W VCT 35 SSE BAZ 25 W 3T5 20 NW 11R 10 NNW UTS 20 W JAS
20 SSE JAS 25 SSW KVBS 20 N KHQI 25 E KVAF 20 W KVAF.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 E IRK CDJ 20 NW STJ 10 E HJH 10 W JYR 15 S TQE 25 E ADU
20 W CID 25 ENE IOW 20 SW MLI 25 WNW GBG BRL 25 W EOK 20 E IRK.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 SE JYL 35 SSW AGS 20 NNW MLJ 15 S LZU 10 ENE RYY 15 NE RMG
30 N 4A9 40 N MDQ MQY 40 S GLW 10 SSE EKQ 25 WNW 1A6 30 SW LNP
VJI 10 N GEV UKF HKY 10 N EHO EHO 25 ESE GSP 25 E GRD 30 WNW CAE
20 NW OGB 10 S OGB 20 W CHS HXD 20 SE JYL.


MID TO UPPER TX COAST

A MARGINAL EXCESSIVE RAINFALL RISK AREA WAS MAINTAINED ALONG THE
MID TO UPPER TX COAST FOR THE UPCOMING DAY 1 PERIOD AHEAD OF SLOW
MOVING MID TO UPPER LEVEL VORTS EXPECTED TO IMPACT THE TX GULF
COAST.  CONFIDENCE ON THE EXACT HANDLING OF THESE VORTS IS LOW AS
IS THE RESULTANT CONVECTIVE EVOLUTION.  WITH PW VALUES REMAINING
ABOVE AVERAGE FROM PERSISTENT SOUTHERLY LOW LEVEL FLOW OFF THE
WESTERN GULF AND THE SLOW MOVEMENT OF THE MID TO UPPER LEVEL
VORTS---LOCALLY HEAVY TO EXCESSIVE RAINFALL AMOUNTS ARE POSSIBLE.
WHILE THE LATEST MODELS DIFFER ON MANY OF THE SHORTER TERM
DETAILS--THERE IS A CLEAR MODEL SIGNAL FOR THE HEAVY TO LOCALLY
EXCESSIVE AMOUNTS ACROSS THIS AREA.

UPPER TN VALLEY---SOUTHERN APPALACHIANS INTO PORTIONS OF THE
SOUTHEAST

A MARGINAL RISK AREA IS DEPICTED DAY 1 IN THE VICINITY OF A
SURFACE FRONTAL BOUNDARY FORECAST TO LIE FROM THE UPPER TN VALLEY
INTO THE SOUTHERN APPALACHIANS AND SOUTHEASTERN U.S.  OVERRUNNING
OF THIS BOUNDARY FROM SOUTH SOUTHWEST LOW LEVEL FLOW OVER THE TN
VALLEY AND SOUTHEASTERLY LOW LEVEL UPSLOPE FLOW INTO THE SOUTHERN
APPALACHIANS WILL SUPPORT POTENTIAL FOR WIDESPREAD MODERATE TO
HEAVY RAINS FROM CENTRAL TO EASTERN TN INTO WESTERN NC---NORTHEAST
GA AND ACROSS LARGE PORTIONS OF SC.  SLOW MOVEMENT OF CELLS WILL
POSE THE THREAT FOR ISOLATED RUNOFF ISSUES ACROSS THESE REGIONS.

SOUTHEAST NEBRASKA---SOUTHERN IA---FAR NORTHERN MO

THE TRAILING SURFACE FRONTAL BOUNDARY FROM THE LOW MOVING INTO THE
UPPER MS VALLEY/UPPER LAKES REGION WILL BECOME ORIENTED WEST TO
EAST FROM THE CENTRAL PLAINS INTO THE MID TO UPPER MS VALLEY
TUESDAY INTO TUESDAY NIGHT-EARLY WEDNESDAY.  CONVECTION SHOULD
BECOME INCREASINGLY ACTIVE ALONG THIS FRONT DURING THE SECOND HALF
OF THE DAY 1 PERIOD AS THE LOW LEVEL FLOW INTO THE BOUNDARY
STRENGTHENS.  THE GREATEST RISK OF ANY RUNOFF ISSUES APPEARS TO BE
TOWARD THE END OF THE DAY 1 PERIOD WHEN THE LOW LEVEL FLOW WILL
BECOME INCREASINGLY PARALLEL TO THE FRONTAL BOUNDARY---SUPPORTING
POTENTIAL FOR A SHORT PERIOD OF TRAINING OR BACK BUILDING OF CELLS
FROM SOUTHEAST NEBRASKA---ACROSS SOUTHERN IA AND FAR NORTHERN MO.


ORAVEC

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