Quantitative Precipitation Forecast
Issued by NWS

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000
FOUS30 KWBC 210738
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
337 AM EDT THU MAY 21 2015

...VALID 12Z THU MAY 21 2015 - 12Z FRI MAY 22 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
70 NW MMMV 115 SSW 6R6 60 WSW 6R6 40 S FST 55 NNE 6R6
20 WNW E29 15 SW ECU 15 SW HDO 25 SE SSF 40 NNW VCT 20 N VCT VCT
10 WNW 2R8 25 SSE BKS 15 WNW MFE 50 ENE MMMY 50 NW MMAN
70 NW MMMV.


...PORTIONS OF WEST AND SOUTH TEXAS FROM THE BIG BEND TO THE LOWER
RIO GRANDE VALLEY...

PROGRESSIVE MCS EARLY THURSDAY MORNING WILL GIVE WAY TO A PERIOD
OF DRYING LATER THIS MORNING INTO THE EARLY AFTN. THE MODELS HAVE
HAVE BEEN DOING A POOR JOB IN HANDLING THIS MCS (AT LEAST IN TERMS
OF QPF)... INCLUDING MOST OF THE HIGH RES RUNS OUTSIDE OF RECENT
HRRR RUNS. THE NEXT SHORTWAVE UNDERCUTTING THE BROAD UPPER LOW
WILL REACH THE AZ/MEXICO BORDER BY 00Z. AS THE UPPER LEVEL FLOW
BECOMES INCREASINGLY DIFFLUENT AHEAD OF THIS NEXT
WAVE...OROGRAPHICALLY-ENHANCED CONVECTION WILL FIRE ONCE AGAIN
DURING THE LATE AFTN/EARLY EVENING HOURS ACROSS NORTHERN MEXICO
ALONG AND SOUTH OF THE STATIONARY SURFACE FRONT IN AREA WITH
MODEST DEEP LAYER INSTABILITY (MUCAPES 1500-2500 J/KG).

THURSDAY NIGHT INTO EARLY FRI...THE MODELS SHOW AN MCV AND
ASSOCIATED AREA OF UPPER DIVERGENCE TRAVERSING THE OUTLOOK
AREA...COINCIDING WITH SE-S LOW-LEVEL INFLOW INCREASING TO 25-30+
KTS ALONG WITH PWATS OF 1.75-2.00 INCHES AND MUCAPES OF 1000-15000
J/KG. THESE FAVORABLE DYNAMICAL AND THERMODYNAMICAL PARAMETERS
ALONG WITH THE SYNOPTIC-SCALE LOW-LEVEL BOUNDARY TO FOCUS MOISTURE
CONVERGENCE WILL ALLOW FOR LOCALLY HEAVY RAINFALL...AS MUCH OF THE
HIGH RES GUIDANCE SHOWS ISOLATED TOTALS OF 3-6+ INCHES.

HURLEY
$$





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