Area Forecast Discussion
Issued by NWS Brownsville, TX

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000
FXUS64 KBRO 282121
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
321 PM CST WED JAN 28 2015

.SHORT TERM /NOW THROUGH THURSDAY NIGHT/...DEEP SOUTH TEXAS AND THE
RGV WILL CONTINUE TO EXPERIENCE A QUIET WEATHER PATTERN AS AN H5
RIDGE OVER THE SOUTHWEST REMAINS IN PLACE AHEAD OF A  LARGE SCALE
MID LEVEL TROUGH MOVING INTO PLACE OFF THE WEST COAST. SOUTHWEST MID
LEVEL FLOW ACROSS NORTHERN MEXICO WILL CONTINUE TO SPREAD CIRRUS
ACROSS THE REGION. AT THE SFC...WEAK RIDGING OVERHEAD WILL SHIFT TO
THE EAST ALLOWING MINOR RETURN FLOW OFF THE GULF. LOOK FOR LOW TEMPS
TONIGHT FROM ABOUT 55 TO 60 WITH LIGHT ONSHORE WINDS.

HIGH PRESSURE WILL CONTINUE TO EXERT SOME INFLUENCE OVER THE NORTH
GULF AS THE CENTER SHIFTS EAST FARTHER TO THE NORTH...MAINTAINING A
LIGHT SOUTHEAST FLOW INTO THE CWA TONIGHT WITH A BIT OF HIGH CIRRUS.
A WEAK PRESSURE TROUGH WILL SET UP OVER CENTRAL TEXAS TONIGHT AHEAD
OF HIGHER PRESSURE MOVING SOUTH FROM THE HIGH PLAINS...SETTING UP A
LIGHT WIND SITUATION FOR THURSDAY MRNG... WHICH WILL IN TURN SUPPORT
THE POTENTIAL FOR A FEW HOURS OF DENSE MORNING FOG NEAR THE COAST.

AFTER MORNING FOG BURNS OFF THURSDAY WILL BE CLOSE TO A CHAMBER OF
COMMERCE DAY WITH CONTINUED HIGH CLOUDS AND HIGH TEMPS FROM 75 TO
80...SEVERAL DEGREES ABOVE NORMAL. WINDS WILL BE LIGHT SOUTHEAST.

PLAINS HIGH PRESSURE WILL SPREAD SOUTH AND INTO THE CWA THURSDAY
NIGHT. THE HIGH PRESSURE WILL SHIFT WINDS TO LIGHT NORTHEAST BY
FRIDAY MORNING AND CLOUDINESS WILL INCREASE AS A WEAK OVERRUNNING
SITUATION DEVELOPS. MID LEVEL CUT OFF LOW WILL REMAIN TOO FAR WEST
OVER SOUTHERN CALIFORNIA TO AFFECT THE LOCAL AREA...THOUGH CLOUDS
AND RAIN CHANCES WILL BE HIGHER ALONG THE TRAILING EDGE OF THE RIDGE
OVER WEST TEXAS AND NEW MEXICO THURSDAY NIGHT INTO FRIDAY. LOW TEMPS
THURSDAY NIGHT WILL AGAIN BE AROUND 55 TO 60...SEVERAL DEGREES ABOVE
NORMAL.


.LONG TERM...
RAIN CHANCES PICK UP BEHIND THE FRONT SATURDAY NIGHT...LINGER AS
COASTAL TROUGHING DEVELOPS CLOSE BY.

A SLIGHT CHANCE OF SHOWERS CONTINUES ON FRIDAY AS SHALLOW/WEAK FRONT
PUSHES THROUGH EARLY FRIDAY MORNING. FRIDAYS MAX TEMPS LOOK ABOUT 5
TO 10 DEGREES COOLER THAN THURSDAYS WITH LIGHT OVERRUNNING PRECIP
THE MAIN WEATHER FEATURE FOR THE DAY ALTHOUGH CHANCES OF ACTUAL
MEASURABLE PRECIP STILL LOOKS PRETTY LOW WITH NO STRONG LOW LEVEL
CONVERGENCE OR MID LEVEL ASCENT TO REALLY SPARK ACTIVITY.

LIGHT NORTHEASTERLY WINDS SHIFT TO THE SOUTHEAST GIVING WAY TO A
RELATIVELY BREEZY DAY WITH A MODEST WARMUP SATURDAY. LOW LEVEL
MOISTURE INCREASES ON THE SOUTHEASTERLIES IN THE SFC-850MB LAYER BUT
SOUTHWESTERLIES AT 700MB SHOULD CONTINUE TO CAP OFF MUCH IN THE WAY
OF CONVECTION AND KEPT THE RGV METRO AREAS DRIER IN THE FORECAST. A
LITTLE BETTER MID LEVEL ASCENT/MID LEVEL DIFFLUENCE WILL BE PRESENT
OVER THE NORTHWESTERN ZONES AND KEPT A MENTION OF SCHC/CHC SHOWERS
THERE. MODEST DIFFLUENCE CONTINUES IN THE UPPER LEVELS ON SATURDAY
NIGHT AND INCREASES ENOUGH TO SEE A BIT OF AN UPTICK IN SHOWER
ACTIVITY. THE GFS IS QUITE WET...BUT SEEMS TO BE GENERATING
SPURRIOUS MID LEVEL VORT MAXES IN THE 300-500MB LAYER. THE ECMWF
SHOWS A SIMILAR SYNOPTIC PATTERN BUT NOT THE ODD LOOKING MAXES SO
WENT MORE THIS DIRECTION IN THE FORECAST WITH 30S OVER THE RGV AND
40S ALONG THE NORTHERN BORDER.

THROUGH THE DAY SUNDAY IT APPEARS WE WILL BE NEAR THE THRESHOLD
BETWEEN WETTER AND DRIER AREAS WITH A FRONT APPRAOCHING FROM THE
NORTH AMID DECENT MID LEVEL DIFFLUENCE BUT DRIER AIR CONTINUING TO
TRAVEL IN ON 700MB SOUTHWESTERLIES SHOULD KEEP PRECIP COVERAGE LOWER
AND KEPT POPS LOWER IN THE SOUTHERN/METRO AREAS UNTIL THE FRONT
ARRIVES SUNDAY EVENING.

DISCREPANCIES IN THE PASSAGE/EVOLUTION OF SYNOPTIC SCALE FEATURES
OPEN UP FROM THIS POINT BETWEEN THE DETERMINISTIC GFS AND ECMWF. THE
12Z ECMWF HAS A MUCH STRONGER KICKER JET BEHIND A RELATIVELY LARGE
CLOSED LOW EMBEDDED IN A LONGER SHORT WAVE TROUGH OVER NORTHERN
MEXICO MONDAY INTO TUESDAY. THIS RESULTS IN A MORE PROGRESSIVE
PASSAGE OF THIS SYSTEM...ALTHOUGH LESS SO THAN YESTERDAY AS IT
TRENDS CLOSER TO THE GFS. THE SLOWER GFS PROGRESSES THE TROUGH MORE
SLOWLY AND DEVELOPS A SURFACE CYCLONE OVER THE WESTERN GULF COASTAL
WATERS AND SHIFTS IT NORTHEASTERLY WHILE GENERATING QUITE A BIT OF
PRECIPITATION. ANOMALOUS LOOKING MID LEVEL VORTICIES EXIST IN THE
GFS RUN WITHIN THE MID LEVEL FLOW AND APPEAR TO HAVE AN IMPACT ON
THE AMOUNT OF OMEGA/LIFT THATS GENERATED IN THE MODEL AND ULTIMATELY
QPF WHICH LEADS ME TO BELIEVE THE FULL CYLCOGENETIC SOLUTION OF THE
GFS MAY BE TOO STRONG.  THESE VORTS LOOK SIMLIAR TO THE BEHAVIOR OF
THE NAM12 DURING RAPID FLOW OVER THE SIERRA MADRE MOUNTAINS AND MAY
BE RELATED TO THE RECENT INCREASE IN RESOLUTION IN THE GFS MODEL.
THE ECMWF SHOWS A FULL FRONTAL PASSAGE WITH SOME RESIDUAL COASTAL
TROUGHING AND A LOW THAT DEVELOPS FURTHER TO THE SOUTHEAST BEFORE
LEAVING.

GFS ENSEMBLE MEMBERS/MEAN SITS BETWEEN THE TWO...AND PREFER A BLEND
TOWARDS THE GFS SYNOPTIC PATTERN WHICH HAS HAD GOOD RUN TO RUN
CONTINUITY BUT WITHOUT THE IMPACT OF THE SPURRIOUS VORT MAXES. SO
TOOK PIECES OF THE ECMWF BIG PICTURE CONCEPTS IN THIS PORTION OF THE
FORECAST. THE END RESULT IS AN EXTENDED PERIOD OF AT LEAST SOME
PRECIP..STARTING SUNDAY NIGHT BEHIND THE FRONT...DROPPING A BIT
DURING THE DAY MONDAY AND THEN PICKING UP AGAIN MONDAY NIGHT AS
COASTAL TROUGHING STRENGTHENS AS THE MAIN UPPER LOW APPROACHES THE
WESTERN GULF COAST. THE TROUGHING KEEPS AT LEAST SOME RAIN CHANCE IN
THE FORECAST THROUGH TUESDAY MORNING...WITH THE HIGHEST CHANCES OVER
THE GULF AND IN THE COASTAL COUNTIES. CLOUDY AND COOL WEATHER
REMAINS THE RULE THOUGH WITH HIGHS WELL OVER 60 NOT RETURNING UNTIL
WEDNESDAY.  THE PATH/STRENGTH OF THIS RELATIVELY STRONG UPPER LEVEL
LOW THOUGH COMES WITH SOME UNCERTAINTY AND WOULDNT BE SURPRISED TO
SEE AT LEAST SOME INCREASE IN POPS BECOME NECESSARY BUT EXACT TIMING
IS TOO UNCERTAIN TO REALLY BEGIN TO HONE IN RIGHT NOW. /68-JGG/


&&

.MARINE... NOW THROUGH THURSDAY NIGHT...FAVORABLE MARINE CONDITIONS
WILL CONTINUE FOR ANOTHER COUPLE OF DAYS UNDER HIGH PRESSURE. A WEAK
FRONT WILL SHIFT WINDS TO NORTHEAST THURSDAY NIGHT.

FRIDAY THROUGH MONDAY... MODERATE NORTHEASTERLY WINDS WILL SHIFT TO
THE SOUTHEAST ON SATURDAY AND SUNDAY BEFORE A STRONG COLD FRONT
SWEEPS ACROSS THE LOWER TEXAS COAST SUNDAY NIGHT. STRONG NORTHERLY
WINDS ARE EXPECTED TO CONTINUE THROUGH THE DAY ON MONDAY AS COASTAL
TROUGHING DEVELOPS BEHIND THE FRONT.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  61  74  59  69 /   0   0   0  20
BROWNSVILLE          61  75  58  71 /   0   0   0  20
HARLINGEN            60  76  57  70 /   0   0   0  20
MCALLEN              60  79  58  70 /   0   0  10  20
RIO GRANDE CITY      59  79  57  71 /   0   0  10  20
SOUTH PADRE ISLAND  MMM MMM MMM MMM / MMM MMM MMM MMM

&&

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

$$

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