National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS64 KBRO 071734 AAB
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1134 AM CST FRI MAR 7 2014

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

&&

.AVIATION...RESIDUAL STRATUS LAYER IS SCATTERING AND LIFTING WITH
PREVAILING VFR CONDITIONS ACROSS THE AREA AS SOUTHEAST WINDS PICK
UP. THOSE SOUTHEAST WINDS WILL BRING MORE LOW MOISTURE TO THE
REGION AND THE TRAJECTORY MAY ALLOW SEA FOG FORMATION LATE THIS
AFTERNOON AND TONIGHT WITH IMPACTS MORE LIKELY AT PIL/SPL AND
VICINITY. EXPECTING A STRATUS LAYER TO REFORM TONIGHT LATE THIS
EVENING AND TONIGHT ACROSS THE REMAINDER OF THE AREA WITH MVFR
CIGS FORECAST...CIGS MAY BE A LITTLE LOWER ON THE NORTHERN
RANCHLANDS. A BRIEF IMPROVEMENT IN CIG IS ANTICIPATED LATE
SATURDAY MORNING BEFORE MORE UNSETTLED WEATHER DEVELOPS IN THE
AFTERNOON AHEAD OF A COLD FRONT. /68-JGG/

&&

.PREV DISCUSSION... /ISSUED 522 AM CST FRI MAR 7 2014/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...PATCHY DENSE FOG HAS FORMED BUT REMAIN HIGHLY VARIABLE
AND IS FLUCTUATING BETWEEN ONE QUARTER AND 5 MILES. MOST OF THE FOG
IS GROUND FOG BUT SOME VERTICAL EXTENSION IS REDUCING VERTICAL
VISIBILITIES BETWEEN 100 AND 200 FEET. LIGHTER FOG IS NOTED AT
KMFE WITH THE VLIFR OCCASIONALLY AT KHRL AND KBRO. THE FOG TO
PERSIST THROUGH 14Z THEN IMPROVE TO VFR. THERE ARE SOME LOWER
STRATUS CLOUDS SEEN OVER EASTERN TAMAULIPAS STATE BUT BELIEVE
THIS DECK WILL MIX OUT AS IT MOVES INTO SOUTH TEXAS IF IT DOES.
OTHERWISE INCREASING SOUTHEAST WINDS TO KICK UP A FEW GUSTS OF 20
TO 25 KNOTS THIS AFTERNOON. STRATUS TO DEVELOP THIS EVENING OR
TONIGHT WITH MVFR CIGS.

PREV DISCUSSION... /ISSUED 344 AM CST FRI MAR 7 2014/

SHORT TERM /TODAY THROUGH SATURDAY/...UPPER RIDGE AXIS OVERHEAD
PRODUCING LIGHT WINDS AND JUST ENOUGH MOISTURE TRANSPORT ACROSS
THE LOWER AND MID VALLEY TO PRODUCE PATCHY DENSE GROUND FOG. SOME
FURTHER VERTICAL EXTENSION AND THICKENING IS POSSIBLE AS WE
APPROACH SUNRISE WITH A POSSIBLE SHORT DURATION DENSE FOG
ADVISORY.

UPPER RIDGE MOVES EAST AND A LOW PRESSURE TROUGH DIGS INTO THE
CENTRAL AND SOUTHERN ROCKIES TODAY. SOUTHEAST WINDS RETURN AND
MOISTURE TRANSPORT INCREASES. PRESSURE GRADIENT STRENGTHENS AS
SURFACE LOW PRESSURE DEEPENS OVER THE SOUTHERN PLAINS. TEMPERATURE
GRADIENT IS NOT INTENSE ENOUGH FOR WINDY CONDITIONS HOWEVER BREEZY
15-25 MPH WILL BE COMMON THIS AFTERNOON ALONG AND EAST OF HIGHWAY
281/69C. TEMPERATURES WARM UP ANOTHER 3 TO 5 DEGREES OVER THURSDAY
WITH INCREASING HIGH CLOUDS TEMPERING THE INSOLATION. OVERALL...A
VERY NICE DAY CONSIDERING WHAT WAS EXPERIENCE EARLY IN THE WEEK.

TONIGHT...PRESSURE GRADIENT REMAINS SOMEWHAT STRONG MAINTAINING A
DECENT SOUTHERLY FLOW OVERNIGHT AND DEEPENING THE GULF MOISTURE.
DEWPOINTS WILL BE ON THE RISE AS WILL THE CLOUDS COVER COUPLED WITH
THE MODERATE SOUTHEAST BREEZE A MILD AND MUGGY NIGHT IS IN STORE.
WINDS TO STRONG FOR DENSE FOG BUT PATCHY FOG MAY LOWER VSBY
OCCASIONALLY ESPECIALLY NEAR THE COAST WHERE THE SEA FOG MAY BE
DENSER.

SATURDAY...MODELS IN GOOD AGREEMENT IS TAKING THE WESTERN TROUGH AND
STRENGTHEN IT AND DEVELOP A CLOSED OVER ACROSS THE SW DESERTS AND
EVENTUALLY INTO NW MEXICO. THIS POSITIVELY TILTED TROUGH TO FURTHER
INCREASE THE MOISTURE TRANSPORT. THE ASSOCIATED COLD FRONT TO
STEADILY MOVE SOUTHEAST APPROACHING THE NORTHERN ZONES BY SUNSET
SATURDAY. MODELS SUGGEST THE APPROACH OF AN UPPER JET TO INCREASE
UPPER DIFFLUENCE AND HELP LIFT OF THE INCREASING MOISTURE. SPC
SWODY2 SUGGEST ELEVATED THUNDER IS POSSIBLE WITH THE JET DYNAMICS
AND INCREASING INSTABILITY. QUESTION IS ON THE TIMING. WITH THE
FRONT STILL PROJECTED NORTH OF THE CWA AT THE END OF SHORT TERM
MIGHT NOT HAVE THE NEEDED FORCING FOR INITIATION IN THE SHORT TERM.
SOME EVIDENCE OF A PREFRONTAL TROUGH OVER THE WESTERN ZONES MIGHT BE
ENOUGH OF A CONVERGENCE ZONE TO GET STUFF ROLLING. THUS...HAVE
BUMPED POPS UP TO CHANCE FOR THE LATER HALF OF THE AFTERNOON IN THE
LOWER AND MID VALLEY TO ACCOMMODATE ANY EARLIER CONVECTION THAT
FIRES. TEMPERATURES TO CLIMB UNDER THE SOUTHERN FLOW BUT DO NOT SEE
ANY HEAT SPIKES WITH LOW LEVEL FLOW REMAINING SOUTHEAST AND LIMITED
MIXING.

LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...THE LONG TERM
FORECAST BEGINS WITH THE ARRIVAL OF THE COLD FRONT BETWEEN MIDNIGHT
AND 6AM SUNDAY. WITH THE H5 TROUGH DIGGING BEHIND THE FRONT...SW
WINDS DOMINATING THE REGION ALOFT AND THE ABSENCE OF A STRONG
POLAR AIRMASS PUSHING IT...THE FRONT WILL MOVE THROUGH AT A
LEISURELY PACE. GOOD DIVERGENCE AHEAD OF THE DIGGING TROUGH AND
IMPULSES ROTATING AROUND IT WILL HELP PRODUCE SHOWER AND
THUNDERSTORM ACTIVITY STARTING AHEAD OF THE FRONT SATURDAY NIGHT
AND CONTINUING INTO MONDAY. THE TROUGH RACES EASTWARD LATE MONDAY
INTO TUESDAY MORNING. NW FLOW BEHIND THE TROUGH AXIS WILL
INTRODUCE A DRIER ATMOSPHERE...BRINGING AN END TO RAIN CHANCES AND
PROMPTLY BRINGING WARMER TEMPERATURES TO THE VALLEY. LONGER RANGE
FORECAST STILL NOT RESOLVING WELL BETWEEN MODELS...SO CONFIDENCE
AFTER TUESDAY IS LOW. MODELS BRING THE NEXT COLD FRONT INTO SOUTH
TEXAS SOMETIME WEDNESDAY...BUT ARE HIGHLY DEPENDENT ON MIDLEVEL
FEATURES...WHICH ARE SIGNIFICANTLY OFFSET FROM ANOTHER BETWEEN
MODELS. ABSENCE OF SFC RETURN FLOW WOULD MAKE ANY FRONTAL PASSAGE
A DRIER AND LESS ACTIVE PASSAGE.

MARINE...
TODAY THROUGH SATURDAY...HIGH PRESSURE RIDGE SHIFTS TO THE EAST
TODAY WITH SOUTHEAST WINDS TO STEADILY INCREASE. GOOD MARINE
CONDITIONS TO CONTINUE THROUGH TODAY WITH ONLY SOME OCCASIONAL
BREEZY CONDITIONS ON THE LAGUNA WHERE THE PRESSURE GRADIENT WILL BE
THE STRONGEST. MODERATE SOUTHEAST WINDS TONIGHT WITH BREEZY
CONDITIONS DEVELOPING SATURDAY AS A COLD FRONT MOVES INTO CENTRAL
TEXAS.  AS THE FRONT APPROACHES LATER SATURDAY SHOWERS AND SOME
THUNDERSTORMS TO DEVELOP.

SATURDAY NIGHT THROUGH TUESDAY...COLD FRONT MOVES GRADUALLY ACROSS
THE COASTAL WATERS PRE-DAWN SUNDAY...WITH BREEZY NORTHERLY WINDS
EXPECTED IN ITS WAKE FOR THE DAY SUNDAY. AIRMASS BEHIND THE FRONT
IS NOT A POLAR AIRMASS...SO STRONGER AND GUSTIER WINDS ARE NOT
ANTICIPATED AT THIS TIME. SMALL CRAFT ADVISORIES ARE STILL
POSSIBLE FOR THE GULF WATERS FOR A BRIEF WINDOW SUNDAY AFTERNOON.
HIGH PRESSURE THE SETTLES ACROSS THE NW GULF LATER
MONDAY...BRINGING LIGHTER AND VARIABLE WINDS TO THE LOWER TEXAS
COASTAL WATERS.

&&

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

$$

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

68/55