Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 252115
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
415 PM CDT TUE AUG 25 2015

.SHORT TERM /NOW THROUGH WEDNESDAY NIGHT/...CURRENT FORECAST IS
GENERALLY ON TRACK WITH REGARDS TO A CALM START...AN UNSETTLED
MIDDLE...AND A CALM END. THE DIFFICULTY IS DETERMINING HOW MUCH
ENERGY WILL SURVIVE FROM THE FAIRLY ROBUST ACTION DIVING
SOUTH/SOUTHWEST OUT OF THE SOUTHEAST TEXAS COAST (GALVESTON TO
PORT ARTHUR) THIS AFTERNOON...AND WHAT WILL THE TIMING BE FOR THE
LOWER/MID VALLEY AND PERHAPS THE RIO GRANDE PLAINS. ONE RULE OF
THUMB THAT CONCERNS ME IS THE POTENTIAL FOR MORE `ACTION` AS
ENERGY EMBEDDED IN NORTHERLY FLOW ALOFT CAN HIT HARD AND
FAST...INCLUDING A LOT OF LIGHTNING AS WELL AS THE POTENTIAL FOR
MICROBURSTS WHICH WAS THE CASE IN THE HOUSTON METRO EARLY THIS
AFTERNOON.

SO...FOR THE SENSIBLE WEATHER WILL KEEP AN EYE ON SCATTERED STORMS
RIGHT ALONG/JUST SOUTH OF THE RIO GRANDE MOVING THROUGH THE MID
VALLEY UNTIL 5/6 PM...OTHERWISE HAVE GONE CLEAR AND CALM FOR THE
BALANCE OF THE OVERNIGHT AND ADDED PATCHY FOG BEFORE AND JUST
AFTER DAYBREAK ACROSS LOCATIONS THAT RECEIVED A GOOD DOSE OF
FOG...LOCALLY DENSE...THIS MORNING. DID NOT GO WHOLE HOG WITH
`AREAS` AND `DENSE` BUT CAN`T RULE OUT BASED ON CALM WINDS AND
MOISTURE POOLING AHEAD OF THE BOUNDARY SO A BRIEF ADVISORY MAY BE
NEEDED FOR THE EARLY MORNING WEDNESDAY COMMUTE.

FOR WEDNESDAY...THE ONLY CHANGE TO THE FORECAST WAS TO DETAIL THE
TIMING OF PRECIPITATION ONSET...STARTING BEFORE SUNRISE ACROSS
THE KING RANCH AND GULF WATERS AND QUICKLY DEVELOPING
SOUTH/SOUTHWEST INTO THE LOWER VALLEY BY MID TO LATE MORNING. THE
ACTIVITY SHOULD PRESS INTO THE MID/UPPER VALLEY WITH PEAK HEATING
AND FOR THIS REASON UPPED RAIN CHANCES TO 30 PERCENT. ALSO ELECTED
FOR COVERAGE WORDING (ISOLATED TO SCATTERED) WHICH SAYS THAT YES
IT *WILL* RAIN IN SPOTS ACROSS MANY AREAS...BUT COVERAGE WILL NOT
BE TOTAL AND EXACTLY WHERE THOSE AREAS ARE IS INDETERMINATE THIS
FAR OUT.

THE SHORT WAVE AND ASSOCIATED BOUNDARY WILL QUICKLY WHIP SOUTH OF
THE AREA BY EVENING...WITH PRECIPITATION ENDING ACROSS THE KING
RANCH AREA BY LATE AFTERNOON AND EVERYWHERE JUST BEFORE SUNSET.
CLEAR SKIES AND CALM WINDS RETURN FOR THE OVERNIGHT...WITH LOWER
DEWPOINTS ALLOWING LOW TEMPERATURES TO BE SOME 3 TO 5 DEGREES
COOLER THAN ON WEDNESDAY MORNING.


.LONG TERM /THURSDAY THROUGH TUESDAY/...THOUGH HOT...CHAMBER OF
COMMERCE (FOR LATE AUGUST) WEATHER WILL RULE SOUTH TEXAS THURSDAY
THROUGH SATURDAY AS LARGE SLUG OF VERY DRY AIR TAKES UP RESIDENCE
AROUND THE PERIPHERY OF THE SEMI STATIONARY FOUR-CORNERS
RIDGE...COVERING NEARLY ALL OF TEXAS. THE GFS HAS BEEN MOST
CONSISTENT FOR SEVERAL DAYS WITH THE SIGNIFICANT DRYING AND
CONTINUES TO SHOW THIS TODAY.

SO...RAIN IS OUT OF THE PICTURE THROUGH SATURDAY BUT MORE
INTERESTINGLY WILL BE THE HIGH DIURNAL RANGE WHICH MAY APPROACH 40
DEGREES IN SOME SPOTS AS LATE NIGHT TEMPERATURES UNDER MOONLIT
SKIES AND CALM WINDS WILL DROP INTO THE MID TO UPPER 60S FOR MOST
AREAS AWAY FROM URBAN CENTERS...BUT REBOUND HANDSOMELY WITH
SUPER-ADIABATIC LAPSE RATES NEAR THE SURFACE ABOVE 100 ALONG/WEST
OF US 281 AND QUITE POSSIBLY ALL THE WAY TO HIGHWAY 77. FOR THIS
REASON...HAVE GONE WITH THE GFS AND UNDERCUT MORNING LOWS IN SOME
AREAS THROUGH SATURDAY AND GONE A DEGREE OR TWO ABOVE IN ALL AREAS
EXCEPT THE BEACH FOR THE SAME PERIOD.

FOR SUNDAY...THE ECMWF CONTINUES TO TRY TO `NUDGE` PRECIPITATION
INTO THE LOWER VALLEY AND GULF WATERS FROM UPPER TROUGH/SHEAR AXIS
THAT DISCONNECTS FROM THE ORIGINAL EAST COAST TROUGH AND SLIDES
TOWARD THE WESTERN GULF. THE TREND HAS BEEN DRIER OVER THE PAST
COUPLE OF DAYS. AS MENTIONED A FEW DAYS AGO...FIND IT DIFFICULT
FOR MOISTURE TO PENETRATE INTO THE FLOW OF THE RIDGE FROM THE EAST
UNTIL THE WEAK SHEAR/UPPER TROUGH CAN GET OVERHEAD SO AS LONG AS
THE AXIS IS EAST OF TEXAS SEE NO REASON TO BRING RAIN INTO THE
MIX. BOTTOM LINE? WILL KEEP THE ENTIRE WEEKEND DRY BUT WITH AN
INCREASE IN LOW LEVEL SOUTHERLY FLOW WILL GRADUALLY INCREASE
SURFACE HUMIDITY...STILL NOT BAD FOR THE LAST SUNDAY IN AUGUST.

MONDAY AND TUESDAY REMAIN HIGHLY UNCERTAIN AS THE GFS AND ECMWF
ARE NOT VERY BULLISH ON ENERGY ASSOCIATED WITH THE UPPER
TROUGH/SHEAR AXIS WHICH SLIDES ACROSS THE STATE. NOT A LOT OF DEEP
MOISTURE...MOST APPEARS TO REMAIN OVER THE EASTERN/CENTRAL GULF.
HOWEVER...THE ECMWF DOES `PICK UP` THE REMNANT TROUGH AND PULL IT
TO EAST TEXAS WITH RIDGE REBUILDING...SHUNTING MOST MOISTURE TO
THE EAST AND NORTHEAST AND REDUCING CHANCES TO SLIGHT AT BEST.
GFS KEEPS A HANGBACK TROUGH/AXIS AND NUDGES DEEPER MOISTURE TOWARD
SOUTH TEXAS AT THE END OF THE PERIOD. REMAINS TO BE SEEN...SO FOR
NOW ACTIVATED SEA BREEZE FOR 20/30 PERCENT CHANCES MONDAY AND
LESSER CHANCES MAINLY TOWARD THE COAST TUESDAY.

&&

.MARINE...TONIGHT THROUGH WEDNESDAY NIGHT: THE BIG THREAT WILL
COME MORE FROM GUSTY THUNDERSTORMS MAINLY WEDNESDAY MORNING THAN
BACKGROUND WINDS...WHICH AT MOST WILL REACH 10 TO 15 KNOTS FROM
THE NORTHEAST BEHIND THE BOUNDARY. A BIT RISKY FOR MORNING FISHING
TRIPS AS SOME STORMS COULD GUST TO GALE FORCE...NOT TO MENTION
FREQUENT CLOUD TO WATER LIGHTNING WHERE THEY FIRE UP.

THAT ALL ENDS WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT LOOKS LIKE
SMOOTH SAILING...LITERALLY...WITH LIGHT WINDS AND SLIGHT SEAS.

THURSDAY THROUGH SUNDAY: SMOOTH SAILING INDEED! LIGHT WINDS...10
KNOTS OR LESS...AND SLIGHT SEAS...2 FEET OR LESS...WILL DOMINATE
THE PERIOD SO SOME GREAT BOATING AND FISHING WEATHER ON TAP.

&&

.FIRE WEATHER...NO ISSUES THROUGH WEDNESDAY NIGHT BUT AM A LITTLE
CONCERNED THURSDAY AND FRIDAY IN PARTS OF STARR...JIM
HOGG...ZAPATA...AND PERHAPS A FEW AREAS OF WESTERN/NORTHERN
HIDALGO AND BROOKS COUNTY AS AFTERNOON HUMIDITY WILL FALL INTO
THE MID TEENS EACH DAY...AND PERHAPS IN A FEW SPOTS SATURDAY. MORE
THAN THE HUMIDITY IS THE FACT THAT DROUGHT CONDITIONS ARE
DETERIORATING...THERE`S PLENTY OF BRUSH FROM LAST SPRING`S
RAINS...AND GUSTY EASTERLY AFTERNOON WINDS COULD REACH 20 MPH AND
CAUSE A FAIRLY RAPID SPREAD OF ANY FIRE THAT STARTS. MAY NEED TO
ISSUE A FEW FIRE DANGER STATEMENTS AS THE SITUATION
EVOLVES...SOMETHING TO KEEP AN EYE ON.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  77  93  73  94 /  10  20  10   0
BROWNSVILLE          77  95  74  96 /  10  30  10   0
HARLINGEN            75  98  71  99 /  10  30  10   0
MCALLEN              78 100  75 101 /  10  30  10   0
RIO GRANDE CITY      76 101  74 101 /  10  20  10   0
SOUTH PADRE ISLAND   78  89  77  88 /  10  30  10   0

&&

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

$$

THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
HTTP://WEATHER.GOV/RGV

52/BSG


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