Area Forecast Discussion
Issued by NWS Brownsville, TX

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS64 KBRO 210607 AAB
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
107 AM CDT TUE APR 21 2015

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

&&

.AVIATION...HIGH LEVEL CLOUDS CONTINUE TO STREAM OVERHEAD COURTESY
OF SOUTHWEST FLOW ALOFT WITH LOW AND MID LEVEL CLOUDS PREVAILING
NEAR THE COAST. CEILINGS RANGE FROM 2200 FEET AT BRO TO NEAR
12000 FEET AT EBG. EXPECT A MIX OF VFR/MVFR CEILINGS FOR THE NEXT
FEW HOURS BEFORE MVFR CONDITIONS SETTLE IN AFTER 08Z. IFR
CONDITIONS SHOULD DEVELOP AROUND 12Z AS ABUNDANT LOW TO MID LEVEL
MOISTURE ACROSS NORTHEAST MEXICO SURGES NORTHWARD AS A WARM FRONT.
CEILINGS AND VISIBILITIES WILL BE REDUCED DUE TO LOW CLOUDS AND
FOG THROUGH 18Z. CONDITIONS WILL IMPROVE THIS AFTERNOON WITH BRIEF
PERIODS OF MVFR POSSIBLE IN SHOWERS. MVFR CONDITIONS EXPECTED TO
RETURN AT LOCAL AERODROMES AFTER 01Z.

&&

.PREV DISCUSSION... /ISSUED 648 PM CDT MON APR 20 2015/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...SATELLITE IMAGES AND SURFACE OBSERVATIONS INDICATE LOW
CLOUDS ACROSS THE COASTAL SECTIONS OF THE CWA EARLY THIS EVENING
WITH HIGH CLOUDS ACROSS THE CWA. CEILINGS WERE NEAR 2200FT AT KBRO
TO NEAR 12000FT AT KEBG. VISIBILITIES WERE NEAR 5SM WITH HAZE AT
KAPY. EXPECT MVFR TO IFR CONDITIONS TO DEVELOP LATE THIS EVENING
INTO EARLY TUES MORNING AS ABUNDANT LOW TO MID LEVEL MOISTURE
ACROSS NORTHEAST MEXICO MOVES NORTHWARD AS A WEAK COLD FRONT
ACROSS NORTHEAST MEXICO MOVES NORTHWARD AS A WARM FRONT. CEILINGS
AND VISIBILITIES WILL BE REDUCED DUE TO LOW CLOUDS AND FOG THROUGH
18Z. CONDITIONS WILL IMPROVE TUES AFTERNOON WITH SHOWERS
DEVELOPING IN THE VICINITY OF LOCAL AERODROMES.

PREV DISCUSSION... /ISSUED 303 PM CDT MON APR 20 2015/
SHORT TERM.../NOW THROUGH TUESDAY NIGHT/...NICE COLD FRONT BLEW
THROUGH THIS MORNING WITH THE GFS THE WINNER OF THE MODEL SUITES.
ONLY ISSUE WAS THE FRONT HAD SUCH A GOOD PUSH FROM THE STRONG
UPPER TROUGH OVER THE MID WEST THAT IT MOVED TO FAR SOUTH FOR ANY
SIGNIFICANT RAINFALL TO IMPACT THE REGION. LIGHT OVERRUNNING
RAIN/SHOWERS CONTINUE TO FORM OVER TAMAULIPAS STATE AND DRIFT OVER
PORTIONS OF THE MID AND LOWER VALLEY WITH ONLY TRACE AMOUNTS.

THIS MAY CHANGE LATER TONIGHT AND TUESDAY AS THE FRONT WORKS ITS WAY
BACK NORTH. MODELS SUGGEST WARM AIR ADVECTION INCREASING OVERNIGHT
INTO TUESDAY MORNING AS 925-700MB WINDS TURN SOUTHEAST TO SOUTH.
INCREASING DEWPOINTS AND PWATS TO DEEPEN THE MOISTURE AND SUBTLE
LIFT DUE TO THE FRONT TO INCREASE THE CHANCE OF SHOWERS THROUGH
TUESDAY MORNING. BEST CHANCES ARE ALONG THE RIVER AND IN THE RGV
WITH LOWER CHANCES IN THE NORTHERN RANCHLANDS. AS FOR
THUNDERSTORMS...INSTABILITY INCREASES THROUGH THE DAY HOWEVER AN
INCREASE OF SW-W FLOW OFF THE SIERRA MADRES BETWEEN 800-700MB
DEVELOPS A CAP THROUGH THE AFTERNOON. THIS MAY CUT OFF ANY CHANCE
FOR THUNDER BUT WITH THE ELEVATED MUCAPE VALUES BETWEEN 1500-2000
J/KG AND THE WARM AIR ADVECTION LEFT A MENTION OF SLIGHT CHANCES
THROUGH THE DAY.

OVERNIGHT TEMPERATURES TO LOWER TO NEAR NORMAL WITH PLENTY OF CLOUD
COVER TO HALT ANY FARTHER DECREASE. TUESDAY PLENTY OF CLOUDS AND THE
RAIN COVERAGE TO KEEP TEMPERATURES ON THE LOW SIDE EARLY ON THEN A
GRADUALLY RISE IN THE AFTERNOON AS SOUTHEAST WINDS INCREASE WITH THE
NORTHWARD PUSH OF THE WARM FRONT. A BLEND OF THE MODELS SEEM A GOOD
COMPROMISE AT THIS TIME. TUESDAY NIGHT LOWS WILL MUCH WARMER AS LOW
70S DEW POINTS BECOME REESTABLISHED.

LONG TERM.../WEDNESDAY NIGHT THROUGH MONDAY NIGHT/...A ELONGATED
TROUGH DOMINATES THE EAST COAST WHILE RIDGE BUILDS FROM THE WEST
WEDNESDAY INTO THURSDAY ACROSS SOUTH TX. WARM FRONT SLOWLY MOVES
NORTH EARLY IN THE LONG TERM AS RIDGE AMPLIFIES AND CUT OFF LOW
OVER BAJA CA MOVES INLAND. THIS RIDGE OVER THE AREA WILL RETURN
SOUTHERLY FLOW ACROSS SOUTH TEXAS AND WARM TEMPERATURES WEDNESDAY
AND THURSDAY. HIGH TEMPS WILL RANGE NEAR 90S FOR THE WEST AND MID
TO UPPER 80S NEAR THE COAST. THE TROUGH TOWARDS THE WEST PUTS S
TEXAS ON A VERY DIFFLUENT FLOW ALOFT WEDNESDAY AFTERNOON AND EVE
INCREASING THE STRONG DEEP-LAYER SHEAR AND THE INSTABILITY WHICH
COULD DEVELOP SOME STRONG THUNDERSTORM LATE WED AFTERNOON AND
EVE. THIS SYSTEM WILL ENHANCE CONVECTION ALONG THE SIERRA MADRE
AND POSSIBLY REACH THE WESTERN COUNTIES OVERNIGHT. BOTH 12Z
GFS/ECMWF SHOW AN MCS DEVELOPING IN THE RIO GRANDE PLAINS NORTH OF
LAREDO AND SHIFT TOWARDS THE EAST THURSDAY NIGHT INTO FRIDAY. BOTH
MODELS SUGGEST HIGH AMOUNTS OF QPF. THIS COULD INDICATE SOME
STRONG CONVECTION WITH POTENTIAL TO BECOME SEVERE WITH
HAIL...DAMAGING WINDS ..FREQUENT CG LIGHTNING AND HEAVY DOWNPOURS.
AS THE COOLER SURFACE AIR SETTLES IN THE INSTABILITY QUICKLY
WEAKENS EARLY FRIDAY MORNING DIMINISHING THE POTENTIAL FOR MORE
SHOWERS DURING THE DAY. THE MAIN CONCERNED WITH THIS PATTERN WILL
BE THE POTENTIAL FOR FLOODING IN POOR DRAINAGE AREAS. ASIDE TO THE
FACT THAT MOST OF THE SOIL IN THE CWA IS ALREADY WELL SATURATED.

FOR THE WEEKEND...THE UPPER TROUGH SWINGS NORTHEAST INTO THE CENTRAL
PLAINS INTO SATURDAY WHILE SOME OF THE ENERGY REMAINS ALONG THE CA
COAST. THE FIRST SHORTWAVE WILL FILTER IN DRY AIR INTO THE CENTRAL
PLAINS SATURDAY. AS A RESULT RAIN CHANCES CONTINUE INTO EARLY SATURDAY
BUT DIMINISH IN THE EVENING AS THE DRY AIR MAKES ITS WAY INTO THE AREA.
TROUGH OVER THE PACIFIC COAST WILL MOVE EAST SUNDAY INTO MONDAY WHICH
RETURNS THE SOUTHEAST FLOW ACROSS THE AREA AND GULF MOISTURE SURGES
ACROSS THE SIERRA AND INTO SOUTH TEXAS. TEMPERATURES WILL BE IN THE 90S
DURING THE DAY AND LOW TO MID 70S OVERNIGHT THROUGH TUESDAY.

MARINE...NOW THROUGH TUESDAY NIGHT...NORTHEAST FLOW TO SLOWLY
TAPPER OFF TURN GRADUALLY EAST TONIGHT AND SOUTHEAST TUESDAY.
GRADIENT TO SLACKEN BECOMING LIGHT TO MODERATE. SMALL CRAFT
ADVISORIES HAVE BEEN CANCELLED FOR THE LAGUNA MADRE AND LIKELY BE
ALLOWED TO EXPIRE AROUND 4 PM FOR THE OFFSHORE WATERS. SURFACE HIGH
PRESSURE BUILDS OVER THE NORTH CENTRAL GULF THROUGH MID WEEK WITH
MODERATE SOUTHEAST WINDS RETURNING AND MAINTAINING A MODERATE SEA
AND SWELL CONDITION.

THURSDAY THROUGH MONDAY/...EASTERLY FLOW WILL BE IN PLACE EARLY IN THE
LONG TERM PERIOD SHIFTING SOUTHEAST DURING THE DAY. ISOLATED SHOWERS AND
THUNDERSTORMS WILL BE ENHANCE ACROSS THE GULF WATERS AND MOVE NORTHWARD. SCEC
IS POSSIBLE IN THE AFTERNOON BUT QUICKLY DIMINISH BY THE EVENING. THE WINDS
BEGIN TO SHIFT MORE SOUTHERLY INTO THURSDAY WITH DRIER CONDITIONS EXPECTED.
THE GRADIENT STRENGTHEN ONCE AGAIN BUT WILL BE MORE SOUTHERLY AND IT HAS A
POTENTIAL FOR SCEC ONCE AGAIN IN THE AFTERNOON. THE SAME TREND CONTINUES
THROUGH FRIDAY RELAXING THE GRADIENT INTO SAT AS A FRONT MOVES THROUGH THE
GULF WATERS. A FEW ISOLATED SHOWERS WILL BE POSSIBLE THROUGH THE
PERIOD.

&&

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

$$

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

63


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.