Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 220048
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
847 PM EDT THU MAY 21 2015

...VALID 01Z FRI MAY 22 2015 - 12Z FRI MAY 22 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...




...SOUTH TEXAS TO THE RIO GRANDE VALLEY...

WITH THE EXCEPTION OF THE SOUTH TEXAS COAST AREA WHERE COLD TOP
CONVECTION CONTINUES TO SETTLE SWD NEAR INTERSECTION OF COLD FRONT
AND N/S COASTAL TROF...FOCUSING/TRIGGER MECHANISM FOR ORGANIZED
CONVECTION COMING THROUGH THE BIG BEND AREA INTO THE RIO GRANDE
VALLEY IS A LITTLE LESS CERTAIN FOR THE REMAINDER OF THE OVERNIGHT
PD.  STG HEIGHT FALLS PUSHING ACRS NM/EXTREME W TX AT 00Z ARE FCST
TO LIFT RAPIDLY NEWD DURING THE OVERNIGHT PD..LIKELY TAKING BEST
SYNOPTIC LIFT IN THE FORM OF OVERRUNNING RAIN/ELEVATED CONVECTION
ACRS ERN NM..THE TX PANHANDLE REGION INTO WRN OK ERN CO AND WRN
KS.  WHILE THE BETTER INSTABILITY IS FCST TO REMAIN ACRS SOUTH TX
ALONG WITH PWS IN EXCESS OF 1.75 INCHES...THE LOW/MID LEVEL
FORCING REMAINS ILL-DEFINED.  CONVECTION DVLPG ACRS THE NRN MEX
MTNS MAY TEND TO DRIVE SEWD SOUTH OF THE RIO GRANDE ALONG AXIS OF
HIER INSTABILITIES..WITH 85H SPEED DIVERGENCE FCST JUST N OF THE
RIO GRANDE NOT ESPECIALLY CONDUCIVE FOR WIDESPREAD ORGANIZED
CONVECTIVE ACTIVITY.

WITH RELATIVELY LIGHT WINDS ALOFT...COULD NOT RULE OUT SOME SLOW
MOVING STORMS THAT COULD PRODUCE SOME SHORT TERM HEAVY RAINFALL
RATES OF 2+ INCHES PER HR..BUT OVERALL BELIEVE THESE STORMS SHOULD
BE RATHER ISOLD GIVEN THE ABOVE REASONING AND VERY LITTLE SUPPORT
FROM HI RES MODEL CONSENSUS INCLUDING HRRR FOR LARGER SCALE
ORGANIZED MCS ACTIVITY ACRS THIS REGION OVERNIGHT.  FOR THIS
REASON..HAVE REMOVED SLIGHT RISK ACRS SOUTH TX FOR THE REMAINDER
OF THE OVERNIGHT PD THINKING EXCESSIVE RAINFALL THREAT WILL BE
RATHER ISOLD.

SULLIVAN
$$





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