Severe Thunderstorm Warning 1, NWS Brownsville, TX

DEEP SOUTH TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
225 PM CST SAT JAN 31 1998

CURRENTLY...KBRO REFLECTIVITY SHOWS SCT RW ACROSS TXZ250-251-253
254-255 MOVING N-NE AT 5 TO 10 MPH.  VIL LEVELS WITH THESE CELLS
REMAIN <25 KG/M2 WITH ECHO TOPS REMAINING <27 KFT.   LDS GPH
SUPPORTS THIS BY SHOWING NIL STRIKES ACROSS DEEP SOUTH TEXAS WITH
STRIKES LIMITE TO THE STRONGER CONV MOVING ACROSS BEE COUNTY IN
CRP/S CWA.  THE MORNING BRO SOUNDING IS SIMILIAR TO SURROUNDING DRT
AND CRP SOUNDINGS BY SHOWING LOW CAPE VALUES (217-582 RANGE)...CAP
VALUES <1.0 DEG...PWAT VALUES FROM 1.00 TO 1.20 INCHES AND WET BULB
ZERO VALUES FROM 8000 TO 9000 KFT.  HOWEVER...THE BIG DIFFERENCE
REVEALS ITSELF IN THE LI CAT WHICH SHOWS MARKEDLY MORE UNSTABLE AIR
(-3 TO -6 RANGE) AT DRT AND CRP.  THE LATEST SWODY1 DISC ESTIMATES
THAT CAPE VALUES OVER THE CRP CWA HAS INCREASED INTO THE 1000 TO
1500 J/KG RANGE AS HIGHER LOW LEVEL DEWPOINTS CONTINUE TO BE
ADVECTED NORTHWARD IN THE STRONG S-SE LOW LEVEL FLOW.  CURRENT ADAP
CHARTS SUPPORT THIS BY SHOWING THAT SURFACE LI/S AROUND THE REGION
REMAIN IN THE -4 TO -6 RANGE OVER DEEP SOUTH TEXAS AND THE COASTAL
BEND AREA.  THE CURRENT STG/SVR CONV OVER CRP/S CWA IS ALSO
REFLECTED IN THE ADAP SMC CHART WHICH SHOWS HIGH SURFACE MOISTURE
CONVERGENCE VALUES BULLSEYED OVER THE LIVE OAK/BEE COUNTY AREA.

ALTHOUGH INSTABILITY HAS REBOUNDED ACROSS THE AREA...UPPER LEVEL
SUPPORT IS WANING AS THE 5H TROUGH AND VORT MAX THAT WAS OVER THE
WESTERN AND CENTRAL PORTIONS OF TX AT 12Z THIS MORNING BEGINS TO
WEAKEN AND ADVECT NORTHEAST OVER THE RED RIVER VALLEY AND PANHANDLE
REGIONS BY 00Z THIS EVENING.  THE LATEST VSBL SATL LOOPS REFLECT
THIS BY SHOWING A VERY DISTINCT CLEARING LINE MOVING EASTWARDS FROM
NEAR DFW TO NEAR DRT.  DESPITE THIS...FWC GUIDANCE DOES NOT BRING
THE POST TROUGH SURFACE FRONT/TROUGH THROUGH THE AREA UNTIL TOMORROW
AND FEEL THAT THE CONV POTENTIAL WILL REMAIN RESONABLE UNTIL THEN
DUE TO THE LINGERING LOW AND MID LEVEL INSTABILITY AND LOW LEVEL
FORCING.

WILL FOLLOW FWC TEMP AND WND GUIDANCE FOR THE MOST PART AS DRIER
AIR BEGINS TO ADVECT INTO THE REGION BRINGING DEWPOINTS INTO THE
LOWER TO MIDDLE 40S BY LATE MONDAY.

SO FOR TXZ248>255...

.TONIGHT...BECOMING PARTLY CLOUDY WITH A 20 % CHC FOR RW/TRW.
SOUTHEAST WIND 5 TO 10 MPH.

.SUNDAY...MOSTLY CLOUDY WITH A 40 % CHC FOR RW/TRW. SOUTHEAST WIND
NEAR 10 MPH BECOMING NORTH 15 TO 20 MPH IN THE AFTERNOON.

.SUNDAY NIGHT...MOSTLY CLOUDY WITH A <20 % CHC FOR RW.

.MONDAY...PARTLY CLOUDY WITH A 20 % CHC FOR RW.

IN THE 3 TO 5 DAY RANGE (TUE-THU)...THE PMDEPD DISC STATE THAT
MODELS ALL AGREE THAT THE NORTHERN GULF OF MEX 5H CLOSED LOW WILL
BE A MAJOR WX-MAKER FOR THE EASTERN SEABOARD.  FOR THE WESTERN
GULF...5H RIDGING WILL BEING TO DOMINATE THE AREA ON THE HEELS OF
THE 5H LOW AND WILL PROVIDE A FAIRLY BENIGN WX PATTERN FOR THE
FORECAST AREA THROUGH EARLY THUR.  HOWEVER...MODELS SHOW ANOTHER 5H
TROUGH MOVING ONTO THE PACIFIC COAST AND BRINGING ANOTHER PACIFIC
SURFACE INTO WEST TX BY 12Z THUR.  FOR WORDING OF EXTENDED WOULD
LIKE...TUE & WED...MOSTLY SUNNY.

CWF...OFFSHORE BOUNDARY LAYER WIND PROGS REMAIN IN THE 20-25 KT
THROUGH SUNDAY MORNING AND SEE LITTLE REASON TO DISAGREE. BUOY020
WINDS SHOW CONDITIONS ESE WNDS NEAR 20 KNOTS WITH SWELLS 6 FT AT 6
SECONDS.  SO WOULD LIKE TO MAINTAIN MENTION OF SMALL CRAFT EXERCISE
CAUTION IN THE 1ST PD.  FOR WORDING...TONIGHT...SE WIND 20 KT.
SEAS 6 FT. WIDELY SCT RW AND TRW.  SMALL CRAFT EXERCISE CAUTIION.
SUN...S WIND 15 KT WITH GUSTS UP TO 20 KT...BECOMING N IN THE
AFTERNOON AT 15 KT.  SEAS 5 FT.  SCT RW AND TRW. SUN NIGHT...N WIND
15 KT WITH GUSTS UP TO 20 KT.  SEAS 6 FT.

BRO EB 060/077 055/076 047 10/40/10/20
MFE EB 059/078 053/077 046 10/40/10/20
RGD EB 057/080 051/078 044 10/40/10/20
SPI EB 064/073 061/070 054 10/40/10/20

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