Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 212315 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
615 PM CDT MON APR 21 2014

.DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.
&&

.AVIATION...MINOR ADJUSTMENTS WERE MADE TO BOTH INITIAL CONDITIONS
AND THE FINAL PERIOD OF THE PREVIOUS TAFS...BUT OVERALL THE CORE
OF THE TAFS WERE LEFT INTACT DUE TO SOUND FORECAST REASONING. VFR
WILL PREVAIL THROUGH THE NEXT SEVERAL HOURS AS WINDS DIMINISH TO
LIGHTER LEVELS WHILE CLOUD DECKS LOWER. MVFR CONDITIONS ARE STILL
EXPECTED CLOSE TO SUNRISE TUESDAY MORNING. VFR WILL RESUME BY THE
MID-MORNING HOURS WITH SURFACE WINDS INCREASING TO MODERATE LEVELS
WHILE CLOUD DECKS RISE.
&&

.PREV DISCUSSION... /ISSUED 212 PM CDT MON APR 21 2014/

SHORT TERM /NOW THROUGH TUESDAY NIGHT/...THE 500 MB TROUGH AXIS
TO OUR NORTH WILL BE SLIDING EAST TONIGHT AND EARLY TOMORROW. THIS
MORNINGS BRO SOUNDING WAS A LITTLE MORE UNSTABLE VERSUS YESTERDAY
WITH A 12Z CAPE OF 1263 J/KG. HOWEVER WINDS ALOFT IN THE SOUNDING
WERE FROM THE W-SW THROUGHOUT MUCH OF THE DEPTH OF THE ATMS AND
THIS WILL LIKELY LIMIT THE CONV POTENTIAL THROUGHOUT THE SHORT
TERM PERIOD AS DRY AIR IS ADVECTED IN FROM THE MID LEVELS. HOWEVER
WILL LEAVE A MENTION OF SLGT CHC POPS OUT WEST THIS EVENING AS AN
ISOLD CELL CANNOT BE RULED OUT AS SOME CONV FIRING OVER THE HIGHER
TERRAIN OF NORTH CENTRAL MEXICO COULD STRAY INTO THE AREA.

WILL TREND DOWN THE POPS FOR TOMORROW AS 500 MB RIDGING WILL BUILD
INTO THE REGION PRETTY QUICKLY IN THE WAKE OF THE TROUGH. WITH LESS
CLD COVER AND INCREASING 1000-500 MB THICKNESS SEE NO REASON FOR
HIGH TEMPS NOT TO EDGE UP TOMORROW.

MODEL GUIDANCE IS IN REASONABLE AGREEMENT THROUGH TOMORROW NIGHT
WITH THE MAV AND MET GUIDANCE IN PRETTY CLOSE TO EACH OTHER FOR BOTH
TEMPS AND POPS. WILL GO CLOSE TO A MODEL CONSENSUS FOR THE SHORT
TERM.

AS THE SURFACE WINDS SLACKEN TONIGHT AND TOMORROW NIGHT THE
POTENTIAL FOR FOG WILL INCREASE ACROSS THE NORTHERN FOUR COUNTIES
AND WILL INCLUDE THIS FOR THE AFTERNOON PACKAGE.

LONG TERM /WEDNESDAY THROUGH MONDAY/...LONGWAVE TROUGH ACROSS
THE INTERMOUNTAIN WEST WILL INDUCE LEE TROUGHING TO OUR WEST AND
RATCHET UP BREEZY SOUTHEASTERLY WINDS WEDNESDAY AND THURSDAY. THE
TROUGH RACES EASTWARD THURSDAY AND HELP DRAG A SURFACE COLD FRONT
INTO NORTHERN TEXAS BEFORE STALLING ON FRIDAY AND LIFT BACK
NORTHWARD ON SATURDAY. A STRONGER TROUGH ENTERS THE WEST COAST
SATURDAY SUPPORTING A SURFACE LOW PRESSURE SYSTEM MOVING THROUGH
THE ROCKIES SUNDAY AND EMERGING INTO THE PLAINS MONDAY. FORECAST
KEPT MOSTLY IN TACT THROUGH SATURDAY NIGHT.

DIFFERENCES IN THE MODELS FOR SUNDAY AND MONDAY AS ECMWF BRINGS A
DRYLINE WITH LOW DEPOINTS BOTH SUNDAY AND MONDAY WITH THE GFS NOT AS
AGGRESSIVE. THE ECMWF IS ALSO FORECASTING A HEAT SPIKE ASSOCIATED
WITH THIS DRY AIR WITH TEMPERATURES WELL INTO THE 100S ACROSS A
MAJORITY OF THE CWA. BASED ON PAST PERFORMANCE OF ECX MOS AT LONG
RANGE WILL DISCOUNT THIS SOLUTION AND KEEP WITH CONSENSUS DAYS 6-7.

FOR POP CHANCES...WILL KEEP SILENT POPS GOING AS LITTLE LIFT AND
STRONG CAPPING SHOULD KEEP MOST PRECIPITATION DEVELOPING ON THE
HIGHER TERRAIN TO THE WEST AT BAY OVERNIGHT EACH NIGHT. MENTION
SLIGHT CHANCE TSTORMS MONDAY AS THE WEEKEND LOW PRESSURE SYSTEM AND
COLD FRONT GET CLOSER.

MARINE...NOW THROUGH TUESDAY NIGHT...WEAK SURFACE RIDGING OVER
THE GULF OF MEX WILL MAINTAIN A PRETTY BENIGN PATTERN OVER THE
LOWER TX BAY AND GULF WATERS. THIS WILL KEEP THE MARINE CONDITIONS
WELL BELOW SCA LEVELS THROUGH TOMORROW NIGHT.

WEDNESDAY THROUGH SATURDAY...ONSHORE WINDS WILL INCREASE
WEDNESDAY INTO THURSDAY AS LOW PRESSURE STRENGTHENS TO OUR WEST.
1-3 FOOT SEAS WILL INCREASE TO 3-5 FEET BY THURSDAY WITH SMALL
CRAFT EXERCISE CAUTION CONDITIONS WEDNESDAY NIGHT AND THURSDAY. A
BRIEF REPRIEVE IN STRONGER WINDS EXPECTED FRIDAY BEFORE WINDS
RATCHET UP AGAIN SATURDAY WITH SMALL CRAFT NEEDING TO EXERCISE
CAUTION.
&&

.BRO WATCHES/WARNINGS/ADVISORIES...NONE.
&&

$$

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