Quantitative Precipitation Forecast
Issued by NWS

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000
FOUS30 KWBC 260913
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
419 AM EDT MON SEP 26 2016

...VALID 12Z MON SEP 26 2016 - 12Z TUE SEP 27 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
145 WNW MMMV 50 SSE E38 55 NNE 6R6 10 W SJT 20 W BWD 20 SE 7F9
20 W GRK RND 30 WSW VCT 10 ENE EFD 20 NE KXIH 40 E KGVX
35 NW KVAF.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
70 SSW 6R6 15 ENE 6R6 10 NNW E29 25 W JCT 30 NE MMPG
25 WSW MMNL.


...SOUTH TEXAS...

CLOSED MID/UPPER LOW WILL REMAIN NEARLY STATIONARY ACROSS NW
MEXICO AND BAJA THIS PERIOD...WHILE THE NORTHERN STREAM TROUGH
CONTINUES TO AMPLIFY INTO A MID-UPPER CLOSED LOW ACROSS THE UPPER
GREAT LAKES. THE MODELS CONTINUE TO SHOW WEAK SUPPORT FOR UPPER
FORCING ACROSS TX IN BETWEEN THESE TWO SYSTEMS... WITH AN UPPER
LEVEL SHEAR AXIS AND A QUASI-STATIONARY SURFACE BOUNDARY OVER
SOUTH TX AND WEAK UPPER DIFFLUENCE EAST OF THE UPPER LOW ACROSS
SOUTHERN AZ/NM INTO WEST TX. MEANWHILE...THE MORE ANOMALOUS PWS
(2.00+ INCHES) WILL CONTINUE TO PRESS SOUTH WITH TIME TOWARD THE
TX GULF COAST...WHILE MODEST PW ANOMALIES (AROUND 1.5 STANDARD
DEVIATIONS ABOVE NORMAL) ALIGN W-E ACROSS SOUTHERN AZ/NM INTO WEST
TX. INSTABILITY WILL ALSO BECOME MORE CONFINED TOWARD SOUTH TX AND
THE GULF COAST WITH TIME DURING THE PERIOD...WITH ONLY MIN MAL
CAPES (200-400 J/KG) ACROSS FAR SOUTHERN AZ NORTH OF THE UPPER
LOW. IN TERMS OF THE QPF...THE 00Z GFS AND ESPECIALLY ECMWF HAVE
TRENDED LIGHTER DURING THE DAY 1 PERIOD ACROSS SOUTH-CENTRAL TX
AND AREAS WEST INTO THE SOUTHWEST...WHICH IS NOT SURPRISING GIVEN
THE WEAKENING SYNOPTIC SUPPORT AND LACK OF DEEP INSTABILITY.
HIGHEST AREAL-AVERAGE TOTALS FROM 12Z MON-12Z TUE WERE BETWEEN
0.50-1.0" ALONG THE RIO GRAND EAST OF THE BIG BEND FROM DRT TO
LRD...WITH A SECONDARY AXIS ALONG THE SOUTH TX GULF COAST BETWEEN
CRP AND BRO WHERE THE INSTABILITY AND 2+ INCH PWS WILL PERSIST.
THE HIGH-RES CAMS SHOW LOCALIZED 3-5" TOTALS ON THE MEXICAN SIDE
OF THE RIO GRANDE...WITH A FEW POCKETS OF 3-5" AMOUNTS ALONG THE
LOWER AND MIDDLE TX COAST. OUTSIDE OF THE ARES ALONG THE RIO GRAND
(NEAR DRT) HIT HARD BY THE RECENT HEAVY RAINS (THUS HAVING LOWER
FFG)...THE RISK FOR FLASH FLOODING DURING DAY 1 APPEARS TO BE
MARGINAL AT BEST.

HURLEY
$$




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