Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 260544 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1244 AM CDT TUE APR 26 2016

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

.AVIATION...SURFACE OBSERVATIONS INDICATE THAT CLOUD BASES ARE
BETWEEN 1500 AND 2000 FEET...WITH 11-3.9 MICRON SATELLITE IMAGERY
SHOWING OVERCAST SKIES. NOT ANTICIPATING CEILINGS TO DROP BELOW
THE 1.5K MARK FOR THE REMAINDER OF THE OVERNIGHT HOURS AS SURFACE
WINDS REMAIN MODERATE. TOMORROW...VFR WILL DEVELOP AND PREVAIL
AFTER SUNRISE BEFORE SLIPPING BACK INTO MVFR TERRITORY BEGINNING
NEAR SUNSET OR SHORTLY THERE AFTERWARDS.
&&

.PREV DISCUSSION... /ISSUED 635 PM CDT MON APR 25 2016/

DISCUSSION...UPDATED FOR LATEST /00Z/AVIATION DISCUSSION BELOW.

AVIATION...CURRENT FORECAST IN PRETTY GOOD SHAPE...WITH MAIN
DIFFERENCE TO ADD THE LAST SIX HOURS FROM 18Z ON THE 26TH THROUGH
00Z ON THE 27TH. THE MAIN ISSUES ARE CEILINGS AND WIND.

MVFR CEILING UNDERWAY IN A BAND NEAR THE COAST AND HAS SPREAD TO
KBRO...ALREADY A HAIR BELOW 2K FEET. 3-HOURLY MODEL SOUNDINGS FROM
THE GFS SEEM FAIRLY ON TARGET...SUGGESTING CEILINGS COULD NEAR
1200 FEET BEFORE MIDNIGHT AT KBRO...SO BROUGHT VALUES DOWN TO
BROAD BRUSH. FORECAST A BIT TRICKY OVERNIGHT FOR CEILINGS IN ALL
AREAS...WITH INHERITED VALUES JUST INTO IFR RANGE /900 FEET/
POSSIBLY A SHADE TOO LOW GIVEN EXPECTED CONTINUATION OF 14-16 KNOT
WINDS WITH HIGHER GUSTS THROUGH THE NIGHT AS 25 TO 27 KNOT
SOUTHEAST FLOW CONTINUES IN THE SHALLOW MIXED LAYER. FOR NOW HELD
ONTO THE FORECAST BASED ON MODEL SOUNDINGS WHICH ARE VERY CLOSE.
AS FOR FUZZY HAZE...CAN`T RULE OUT SOME PERIODS OF 6 MILES BETWEEN
MIDNIGHT AND DAYBREAK BUT LEFT AS P6SM FOR NOW. FOG NOT A FACTOR
IN THE SOUPY AIRMASS.

FOR TUESDAY...WINDS PICK UP NICELY AS CLOUDS ERODE RATHER QUICKLY.
KBRO LIKELY THE LAST TO GO JUST BEFORE NOON THOUGH PESKY MVFR
CEILINGS MAY CONTINUE INTO EARLY AFTERNOON AS THEY DID
TODAY...COURTESY OF ANY SEA BREEZE HELP TO BACK WINDS TO THE
SOUTHEAST RATHER THAN REMAIN FROM THE SOUTH/SOUTHEAST. FULL
SUNSHINE AND GOOD MIXING THROUGH THE INVERSION LAYER WILL KICK
SUSTAINED WINDS OVER 20 KNOTS FROM LATE MORNING THROUGH
AFTERNOON...THOUGH SPEEDS MAY DECREASE AT MCALLEN AS INVERSION IS
ERASED IN THE SUMMER-LIKE HEAT. KEPT AT 20 KNOTS FOR NOW BUT COULD
DIP TO 15 KNOTS BY 20/21Z WITH HEAT SPIKE.
52/BSG

PREV DISCUSSION... /ISSUED 301 PM CDT MON APR 25 2016/

SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...THERE WAS A STOUT
SUBSIDENCE INVERSION PRESENT ON THE 12Z BRO SOUNDING DUE TO
MIDLEVEL RIDGING OVERHEAD WHICH ALLOWED LOW CLOUDS TO DEVELOP
OVERNIGHT. THAT MID LEVEL RIDGE WILL WEAKEN AND MOVE EASTWARD AS A
MID LEVEL CLOSED LOW MOVES ACROSS THE INTERMOUNTAIN WEST THROUGH
TUESDAY THEN EMERGES INTO THE HIGH PLAINS TUESDAY NIGHT. THIS WILL
SUPPORT AN EVENTUAL 993MB SFC LOW ACROSS THE CENTRAL PLAINS.
SOUTHWESTERLY LOW/MID LEVEL SUBSIDENT FLOW WILL OVERSPREAD DEEP
SOUTH TEXAS AND KEEP LOW LEVEL MOISTURE ON SOUTHEASTERLY SFC WINDS
JUST THAT...LOW LEVEL. PWATS WILL INCREASE FROM THE 1.18 INCHES ON
THIS MORNING SOUNDING BUT THE MID LEVELS ARE SO DRY AND MOST
FORCING WELL REMOVED FROM THE AREA THAT THERE IS LITTLE CHANCE FOR
PRECIPITATION ACROSS OUR AREA. WHAT THERE WILL BE THOUGH IS HEAT.
DOWNSLOPING WINDS AND DRIER AIR WILL WORK INTO OUR WESTERN
SECTIONS WHICH WILL CAUSE THE HIGHS TO REACH THE CENTURY MARK
AGAIN. MOST OF THE GUIDANCE HAS INCREASED HIGHS A DEGREE OR TWO
AND HAVE FOLLOWED SUIT WITH LOW 100S MAINLY ACROSS ZAPATA AND
WESTERN STARR COUNTIES AND 90S ELSEWHERE. LOWS WILL BE WARM AND
MAINLY IN THE MID 70S.

LONG TERM /WEDNESDAY THROUGH MONDAY/...THE 12Z MODEL SUITE OUTPUT
SHOWS LITTLE VARIATION FROM PREVIOUS RUNS. MID TO UPPER LEVEL FLOW
REMAINS IN A SPLIT FLOW REGIME WITH A PARADE OF SHORTWAVES TO
TRACK ACROSS THE DESERT SOUTHWEST AND INTO THE SOUTHERN AND
CENTRAL PLAINS. MODELS SHOW EACH SUCCESSIVE WAVE DIGGING A LITTLE
DEEPER WITH RAIN POTENTIAL SHOWN TO INCREASE SOMEWHAT BY NEXT
WEEKEND AND INTO EARLY NEXT WEEK WITH POTENTIAL MCS DEVELOPMENT.
ALTHOUGH CONFIDENCE IN THE GENERAL PATTERN IS ABOVE AVERAGE RAIN
CHANCES AND TIMING OF THE RAIN IS BELOW AVERAGE. MOST OF THE
SENSIBLE WEATHER THIS WEEK WILL BE REFLECTED IN THE HEAT AND HEAT
INDICES WHERE TEMPERATURES AND FEEL LIKE TEMPERATURES WILL BE
PUSHING 100+ DEGREES MUCH OF THE LONG TERM. A DAY TO DAY ANALYSIS
OF THE PROGRESSION OF THESE SHORTWAVES WILL BE CAREFULLY WATCHED
WITH THEIR LOW PRESSURE SURFACE TROUGHS/COLD FRONTS SLOWLY
TRACKING SOUTH AND EAST. FRONTS HAVE A DIFFICULT TIMING REACHING
THIS FAR SOUTH THIS TIME OF YEAR HOWEVER CONVECTION THAT FORMS
ALONG THEM FARTHER NORTH COULD HAVE A TENDENCY TO ALLOW FRONTS
AND/OR THUNDERSTORM LINE/CLUSTERS TO MOVE SOUTH. THIS COULD OCCUR
WEDNESDAY AND AGAIN SATURDAY WHERE POPS ARE SLIGHTLY ELEVATED.

MARINE...NOW THROUGH TUESDAY NIGHT...BUOY 42020 REPORTED
SOUTH-SOUTHEAST WINDS AROUND 14 KNOTS GUSTING TO AROUND 16 KNOTS
WITH SEAS AT 3.3 FEET WITH A PERIOD OF 6 SECONDS AT 13 CDT/18 UTC.
HIGH PRESSURE OVER THE GULF OF MEXICO WILL INTERACT WITH LOW
PRESSURE OVER THE CENTRAL PLAINS AND NORTHERN MEXICO. SMALL CRAFT
WILL LIKELY NEED TO EXERCISE CAUTION ACROSS ALL LOWER TEXAS
COASTAL WATERS THROUGH TUESDAY NIGHT. THERE IS A POSSIBILITY FOR
SMALL CRAFT ADVISORIES AT TIMES IN THE OVERNIGHT HOURS ACROSS THE
GULF WATERS AND THE LAGUNA MADRE ON TUESDAY.

WEDNESDAY THROUGH SATURDAY...WEAK FRONT TO APPROACH THE COAST
LATE WEDNESDAY ALLOW FOR WINDS TO RELAX FOR THE AFTERNOON AND
EARLY EVENING. THE SOUTHEASTERLY FLOW THEN RESUMES WEDNESDAY NIGHT
GRADUALLY STRENGTHENING THURSDAY AND FRIDAY A THE PRESSURE
GRADIENT STRENGTHENS CONSIDERABLY WITH THE APPROACH OF A STRONGER
UPPER LEVEL LOW PRESSURE TROUGH. SEAS TO BUILD AND WINDS WILL BE
STRONG ENOUGH FOR SMALL CRAFT ADVISORY CONDITIONS FRIDAY AND
CONTINUING INTO SATURDAY.

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

$$

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