Quantitative Precipitation Forecast
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FOUS30 KWBC 171309
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
909 AM EDT THU JUL 17 2014

...VALID 15Z THU JUL 17 2014 - 12Z FRI JUL 18 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 ESE SJT 30 S SWW SNK 40 SE LBB LBB 10 SSW PVW 20 E PVW
35 SSW CDS 40 WSW F05 15 S F05 FDR FSI 20 SSW CHK OUN 10 ENE TIK
10 SE CQB 15 NE OKM 15 ESE TQH 25 SE FYV 10 NNW RUE 30 WNW LZK
20 ESE HOT 25 SE BAD 10 ENE JAS 30 SSW JAS 25 ENE CXO 25 ENE LHB
25 E TPL GRK 10 SE 6R9 25 ESE JCT 25 NNW JCT 25 ESE SJT.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 NNW PSN CRS 20 ESE INJ 15 SSW INJ 30 WNW CNW 30 SSE SEP
15 ENE 7F9 30 N 7F9 40 SW RPH 15 W RPH 20 NNE RPH 20 WSW 1F0 ADM
20 WSW AQR 40 E AQR 15 NW DEQ 20 WNW TXK 30 NW SHV 15 E GGG
10 SSW GGG 15 SE TYR 30 NNW PSN.


15Z UPDATE...
SHIFTED MDT RISK AREA SWD ACRS OK TOWARD BETTER INSTABILITY AND
STGR ISENTROPIC LIFT BAND.  RADAR IMAGERY WAS INDICATING SIGNS OF
WEAK ROTATION NEAR THE RED RIVER NEAR SPS AS OF 13Z WHICH MAY HELP
MAINTAIN STGR ISENTROPIC LIFT BAND OF SHWERS/TSTMS THRU PARTS OF
NRN TX INTO SRN OK THROUGH LATE MRNG/EARLY AFTN TO THE NORTH OF
WARM FRONTAL BNDRY.   OTHER ISOLD POCKETS OF HEAVIER CONVECTIVE
RAINS ARE PSBL FARTHER SOUTH IN THE WARM SECTOR OVER CNTL/ERN TX
WITH VERY HIGH PWS...AOA 2 INCHES..LEADING TO SOME VERY HEAVY
SHORT TERM RAINFALL RATES.  ALSO TRIMMED SLIGHT RISK AREA TO THE
WEST WHERE FF THREAT HAS LESSENED.    SULLIVAN   PREVIOUS
DISCUSSION FOLLOWS...

THE SIGNIFICANT AND HEAVY TO LIKELY EXCESSIVE RAINFALL EVENT IS
BEGINNING TO UNFOLD ALREADY THRU PARTS OF THE SOUTHERN PLAINS AND
WILL EXPAND A
BIT SOUTH AND EAST THIS PERIOD.  AT LEAST 2 WELL DEFINED H5
S/WVS..THE 1ST OF WHICH IS NOW ENTERING THE TX AND OK PANHANDLES
AND THE UPSTREAM ONE OVER SOUTHEASTERN WY/NORTHEASTERN CO..WILL
DROP EAST-SOUTHEASTWARD IN THE PREVAILING WEST-NORTHWESTERLY MID
LEVEL FLOW REGIME AND INTERACT WITH A  GENERALLY EAST-WEST
QUASI-STATIONARY FRONTAL BOUNDARY AND ANOMALOUSLY HIGH
MOISTURE/PWS WORKING NORTHWARD FROM THE WESTERN GULF TO SUPPORT AN
EXPANSIVE OVERRUNNING/WARM AIR ADVECTION CONVECTIVE EVENT..WITH
THE HEAVIEST RAINS LIKELY STRADDLING THE RED RIVER.   MANUAL QPF
ENDED UP LEANING TOWARDS THE HIGHER RESOLUTION ECMWF..CANADIAN
GEM..AND ARW SOLUTIONS..ALL OF WHICH SHOWED SIGNIFICANT RAINS
GETTING WELL INTO EASTERN TX..WESTERN LA AND SOUTHERN AR TOWARDS
THE END OF THE PERIOD..WHICH WOULD SEEM REASONABLE GIVEN THE
MODEST WEST-NORTHWESTERLY FLOW REGIME AND THE EXPECTED COLD POOL
DYNAMICS AND THE RESULTING FASTER FORWARD PROPAGATION.  GIVEN BOTH
DYNAMIC AND THERMAL FORCING CONSIDERATIONS..HAVE CONTINUED TO
INDICATE AREAL-AVERAGE QPF AMOUNTS OF 1 TO 4+ INCHES..WITH
ISOLATED RAINFALL AMOUNTS IN EXCESS OF 5 INCHES QUITE
POSSIBLE..ALL OF WHICH IS LIKELY TO LEAD TO RATHER EXPANSIVE
FLOODING CONCERNS FROM OK INTO NORTHERN AND CENTRAL TX AND INTO
WESTERN PARTS OF AR AND LA.

TERRY





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