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000
FXUS64 KBRO 100518
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1218 AM CDT MON MAR 10 2014

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

&&

.AVIATION...EXPECTING TO REMAIN MOSTLY IFR OVER THE NEXT 24 HOURS
AS MID LEVEL LOW TO OUR WEST KEEPS LARGE SCALE LIFT GOING AS WELL
AS COASTAL TROUGHING AND ISENTROPIC LIFT. AREA WILL BE IN AND OUT
OF LIGHT RAIN AND DRIZZLE AS WELL. WINDS WILL MAINLY BE FROM THE
NORTHWEST AOA 10 KNOTS.

&&

.PREV DISCUSSION... /ISSUED 630 PM CDT SUN MAR 9 2014/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...NORTHWEST MEXICO MID LEVEL LOW WILL PROVIDE LARGE
SCALE LIFT OVER THE CWA...WHICH WILL ENHANCE OVERRUNNING PRECIP IN
THE COOL...MOIST SURFACE AIR MASS IN THE SHORT TERM. THUS...LOW
OVC SKIES WITH LIGHT RAIN AND DRIZZLE...PATCHY FOG...AND REDUCED
CEILINGS AND VSBYS WILL BE THE RULE FOR THIS TAF OFFERING. EXPECT
PRIMARILY IFR THE NEXT 24 HOURS.

KBRO 092320Z 1000/1024 35010KT P6SM VCSH OVC006
     FM100900 33008KT 5SM RADZ OVC005
     FM101700 31006KT 1 1/2SM -RADZ OVC004

KHRL 092320Z 1000/1024 34011KT P6SM OVC008
     FM100300 33015KT 4SM BR OVC007
     FM101500 35010KT 2SM BR OVC007
     FM101800 31010KT 1 1/2SM BR OVC004

KMFE 092320Z 1000/1024 34011KT P6SM VCSH OVC012
     FM100300 32007KT 5SM BR OVC007

PREV DISCUSSION... /ISSUED 154 PM CDT SUN MAR 9 2014/

SHORT TERM.../NOW THROUGH MONDAY NIGHT/...COASTAL TROUGHING IS
INTENSIFYING IN THE WEST CENTRAL GULF OF MEXICO WITH WINDS
THROUGHOUT THE CWA OUT OF THE NORTHWEST AMID ABUNDANT LOW CLOUD
COVER. PERIODIC RAIN AND DRIZZLE CONTINUES AND WITH 1 TO 2 DEGREE
DEW POINT DEPRESSIONS AT LEAST SOME FOG APPEARS TO BE FORMING AT
TIMES. TEMPERATURES REMAIN QUITE COOL WITH THE HIGHEST AREA
READINGS IN THE LOW 50S. THE PARENT UPPER LEVEL LOW/TROUGH REMAINS
NEARLY STATIONARY...IF NOT RETROGRADING SLIGHTLY...OVER NORTHWEST
MEXICO WITH A FEW WEAK PERTURBATIONS IN THE SOUTHWEST FLOW AHEAD
OF THE SYSTEM EVIDENT ON WATER VAPOR IN NORTHEASTERN MEXICO HEADED
THIS WAY.

REST OF THE AFTERNOON...EXPECTING LITTLE CHANGE IN CONDITIONS
WITH LIGHT RAIN AND OCCASIONAL BURSTS OF HEAVIER SHOWERS EXPECTED
WITH TEMPS IN THE UPPER 40S TO LOW 50S WITH A PERSISTENT NORTHWEST
WIND. RAINFALL AMOUNTS GENERALLY LOOK TO BE LESS THAN ONE TENTH OF
AN INCH.

TONIGHT...NAM/RAP APPEAR TO TRY TO TIME A SHORTWAVE TROUGH WITH
ACCOMPANYING ENHANCEMENTS TO LARGE SCALE ASCENT AROUND MIDNIGHT OR
A LITTLE LATER. THIS INTENSIFIES COASTAL TROUGHING AND THE RELATED
ISENTROPIC LIFT AND STRATIFORM RAIN...AND HELPS DESTABILIZE THE
COLUMN A BIT THROUGH LIFTING AND COOLING IN THE MID LEVELS WHICH
SHOULD OPEN THE DOOR FOR HEAVIER SHOWERS. FORECAST SOUNDINGS SHOW
MODEST ELEVATED INSTABILITY DEVELOPING AND MENTIONED A SLIGHT
CHANCE OF THUNDER AS THIS WAVE PASSES. PATCHY FOG ALSO APPEARS
POSSIBLE DUE TO WET GROUND AND LOW DEW POINT DEPRESSIONS. WENT WITH
CATEGORICAL/NEAR 100 PERCENT RAIN WORDING IN THE SOUTHEASTERN
THIRD OF THE CWA BLENDING TO HIGH LIKELY POPS IN THE NORTHERN HALF
OF THE REGION. RAINFALL AMOUNTS WILL VARY BASED ON WHO GETS
ENHANCED SHOWER ACTIVITY BUT AROUND ONE TENTH TO ONE QUARTER OF AN
INCH IN CAMERON COUNTY DECREASING TO AROUND ONE TENTH OF AN INCH
IN ZAPATA COUNTY IS FORECAST FOR NOW. TEMPERATURES WILL LIKELY
ONLY COOL A DEGREE OR TWO AMID THICK CLOUD COVER.

MONDAY...THE MAIN UPPER LOW MOVES CLOSER DURING THE DAY MONDAY
WITH NAM/GFS/ECMWF IN GOOD AGREEMENT REGARDING THE INFLUENCE OF
ANOTHER LEADING SMALL SHORTWAVE MOVING ACROSS THE NORTHERN HALF OF
THE CWA KEEPING A DECENT ENVIRONMENT IN PLACE FOR SHOWER ACTIVITY.
ISENTROPIC LIFT/FRONTAL OVERRUNNING CONTINUES WITH GOOD LOW LEVEL
CONVERGENCE IN VICINITY OF THE COASTAL TROUGH WHICH AT THE SURFACE
IS EXPECTED TO MOVE VERY LITTLE DURING THE DAY. 305K ISENTROPIC
SURFACE CHARTS SHOW A LITTLE HIGHER CONDENSATION PRESSURE DEFICITS
IN THE WESTERN HALF OF THE AREA SO WENT WITH LIKELY POPS THERE AND
CATEGORICAL POPS IN THE EASTERN HALF. PRECIP AMOUNTS REMAIN
LIGHT...IN THE ONE TO TWO TENTHS OF AN INCH RANGE...WITH A FEW
LOCALES POSSIBLY PICKING UP MORE IN ENHANCED SHOWER ACTIVITY WITH
THE BEST CHANCES FOR THAT IN KENEDY AND BROOKS COUNTY.

MONDAY NIGHT...THE PARENT UPPER LOW FINALLY MOVES IN OVERHEAD
THROUGH THE NIGHT MONDAY AND COASTAL TROUGHING BEGINS TO EVOLVE INTO
MORE OF A CLOSED CYCLONE AS IT MOVES NORTH UP THE COAST. THIS KEEPS SOME
LOW MOISTURE AND CONVERGENCE IN PLACE THROUGH THE FIRST HALF OF THE
NIGHT AND KEPT CHANCE TO GOOD CHANCE POPS IN THROUGH MIDNIGHT BEFORE
TAPERING THEM DOWN TO CHANCE/SLIGHT CHANCE AFTER MIDNIGHT AS THE
DCVA MOVES EAST OF THE REGION AND THE BEST ISENTROPIC LIFT MOVES
OVER THE WESTERN GULF EAST OF OUR MARINE ZONES. BEGAN TO BREAK UP
CLOUD COVER A BIT BY LATE IN THE NIGHT BUT TEMPERATURES SHOULD STILL
BE HELD UP INTO THE LOW 50S TO UPPER 40S.

LONG TERM.../TUESDAY THROUGH SUNDAY/...THE MID LEVEL TROUGH
SHOULD BE MOVING ACROSS THE AREA AT 12Z TUESDAY AND WELL EAST OF
THE AREA BY TUE AFTERNOON. THIS WILL BRING AN ABRUPT END TO THE
PRECIPITATION AND WE SHOULD SEE AMPLE SUNSHINE AND WARMER
CONDITIONS BY TUE AFTERNOON. HOWEVER...THE WARM UP WILL BE SHORT-
LIVED. ANOTHER MID LEVEL SHORTWAVE DIVING DOWN INTO THE CENTRAL
ROCKIES WILL SET THE STAGE FOR ANOTHER COLD FRONTAL PASSAGE
WEDNESDAY MORNING. THIS FRONT IS EXPECTED TO BE DRY DUE TO LIMITED
MOISTURE AS A RESULT OF THE DRYING AND SUBSIDENCE LEFT IN THE WAKE
OF TUESDAY/S SHORTWAVE. THE GOOD NEWS IS THAT THIS FRONT SHOULD
HAVE A MUCH SMALLER IMPACT ON TEMPERATURES THAN THE LAST SEVERAL
FRONTS. STILL...BREEZY AND A BIT COOLER WEDNESDAY. STILL COOL
THURSDAY...BUT LOOKS LIKE A BEAUTIFUL DAY WITH LIGHT WINDS AND
TEMPS IN THE MID 60S TO NEAR 70 RANGE. A RETURN FLOW FROM THE GULF
IS UNDERWAY FRIDAY THROUGH SATURDAY NIGHT...GRADUALLY WARMING EACH
DAY. WITH THE ABUNDANT LOW LEVEL MOISTURE...MORNING LOW CLOUDS AND
PATCHY FOG ARE ANTICIPATED EACH MORNING OVER THE WEEKEND. YET
ANOTHER COLD FRONT IS EXPECTED SUNDAY. THIS FRONT WILL MAY VERY
WELL BRING ANOTHER DECENT CHANCE OF RAIN TO THE AREA...BUT THE
RAIN CHANCES SHOULD BE MAINLY TIED TO THE PASSAGE OF THE FRONT AND
NOT LINGER FOR MORE THAN A DAY.

ADJUSTMENTS TO THE INHERITED FORECAST PACKAGE WERE MAINLY
CONFINED TO THE EARLIER EXPECTED ARRIVAL OF THE COLD FRONT
WEDNESDAY AND THE ARRIVAL OF THE COLD FRONT SUNDAY. AS A
RESULT...MAX TEMPS WERE LOWERED A FEW DEGREES ON WED AND RAIN
CHANCES WERE INTRODUCED OVER THE WEEKEND...WITH THE BEST CHANCES
FOR SHOWERS OCCURRING ON SUNDAY.

MARINE...NOW THROUGH MONDAY NIGHT...SMALL CRAFT ADVISORIES REMAIN
IN EFFECT FOR ALL WATERS THROUGH MID AFTERNOON AND MAY NEED TO BE
EXTENDED THROUGH THIS EVENING AS COASTAL TROUGHING KEEPS STRONG
NORTHWEST WINDS IN PLACE ACROSS THE LOWER TEXAS COAST. OVERALL
WIND SPEEDS ARE EXPECTED TO TREND DOWNWARD SLIGHTLY THROUGH THE
EVENING INTO THE OVERNIGHT HOURS WITH ROUGH SEAS BECOMING MORE
MODERATE LATE TONIGHT. MODERATE NORTHWEST WINDS AND SEAS ARE THEN
EXPECTED THROUGH MONDAY LIKELY AT EXERCISE CAUTION LEVELS WITH
ADVISORY CONDITIONS POSSIBLE. WINDS ARE EXPECTED TO SHIFT MORE
WESTERLY MONDAY NIGHT BECOMING MORE LIGHT AS LOW PRESSURE MOVES
OUT OF THE AREA.

TUESDAY THROUGH THURSDAY...FAVORABLE MARINE CONDITIONS EXPECTED
TUESDAY WITH DETERIORATING CONDITIONS WEDNESDAY AND WEDNESDAY
NIGHT WITH THE PASSAGE OF THE NEXT COLD FRONT. SMALL CRAFT
CONDITIONS WILL LIKELY BE REQUIRED. CONDITIONS SHOULD IMPROVE
THURSDAY.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 4 AM CDT EARLY THIS MORNING FOR
     GMZ170-175.

&&

$$

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

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