Area Forecast Discussion
Issued by NWS Brownsville, TX

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000
FXUS64 KBRO 301208 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
608 AM CST FRI JAN 30 2015

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

&&

.AVIATION...LIGHT WINDS AND SURFACE MOISTURE COMBINING TO PRODUCE
PATCHY AREAS OF DENSE FOG. LIFR TO IRF CONDITIONS ARE EXPECTED AT
TIMES THROUGH 15Z. A WEAK COLD FRONT MOVES THROUGH SOUTH TEXAS
TODAY WITH LOW LEVEL MOISTURE ON THE INCREASE. MVFR CIGS DEVELOP
THIS AFTERNOON AND THIS EVENING MAINLY BEHIND THE FRONT. A FEW
SHOWERS ARE ALSO POSSIBLE BUT AREAL COVERAGE WILL BE LIMITED SO
NO MENTION IN TAFS AT THIS TIMES. LIGHT EAST TO NORTHEAST WINDS
THIS MORNING BECOMING 10 TO 15 KNOTS THIS AFTERNOON.

&&

.PREV DISCUSSION... /ISSUED 409 AM CST FRI JAN 30 2015/

SHORT TERM /NOW THROUGH SATURDAY/...PATCHY FOG ACROSS THE REGION
THIS MORNING TO GRADUALLY LIFT THROUGH MID MORNING AS A WEAK COLD
FRONT MAKES ITS WAY THROUGH THE CWA. SURFACE HIGH PRESSURE
BUILDING INTO NORTH TEXAS BUILDS MORE EAST THEN SOUTH WITH THE
FRONT WORKING ITS WAY INTO THE LOWER VALLEY AND SOUTH OF THE RIO
GRANDE BY NOON. WINDS TURN NORTHEAST WITH MODEST COLD AIR
ADVECTION WITH MID LEVEL RIDGING BUILDING OVERHEAD AS A WESTERN
TROUGH STRENGTHENS. SLIGHT INCREASE IN GULF MOISTURE IS NOT
SUFFICIENTLY DEEP AND FORCING FROM FRONT IS WEAK TO LIMIT RAIN
CHANCES TODAY. BEST SURFACE CONVERGENCE IS ACROSS THE WESTERN
ZONES WHERE SLIGHTLY HIGHER POPS RESIDE. TEMPERATURES TO COOL OFF
TOWARDS NORMAL WITH HIGHS 6 TOP 10 DEGREES COOLER THEN THE LAST
FEW DAYS. MODELS ARE IN GOOD AGREEMENT WITH BOTH POPS AND
TEMPERATURES.

HIGH PRESSURE SHIFTS EAST AND WESTERN UPPER TROUGH BEGINS TO
INFLUENCE OUR WEATHER REGIME TONIGHT AND SATURDAY. SURFACE WINDS TO
VEER EAST TO SOUTHEAST AND 850MB FLOW STRENGTHENS IN RESPONSE TO
LOWERING PRESSURE OVER THE SIERRA MADRE WITH AND SLOW ADVANCE OF THE
WESTERN COAST TROUGH. LOW LEVEL MOISTURE GRADUALLY DEEPENS BUT WITH
MID LEVEL RIDGE REMAINING OVERHEAD A LAYER OF DRIER AIR LIMITS RAIN
CHANCES. MODELS AND GOING FORECAST CONTINUE WITH LOW GRADE POPS AND
LOW QPF. MAYBE A FEW PEAKS OF SUNSHINE SATURDAY AS SOUTHERLY FLOW
STRENGTHENS AND MIXES OUT SOME OF THE LOW LEVEL MOISTURE. SLIGHTLY
COOLER TEMPERATURES TONIGHT TO RECOVER SATURDAY INTO THE LOWER 70S
AS THE SOUTH WINDS INCREASE.

LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...ISENTROPIC LIFT WILL
BE DECREASING INTO SUNDAY MORNING...WITH A BRIEF DECREASE IN RAIN
CHANCES SUNDAY AFTERNOON. THIS WILL BE SHORT-LIVED AS THE NEXT
STRONG COLD FRONT DRIVES THROUGH TEXAS. MODELS CONTINUE TO
SLIGHTLY BACK UP THE TIMING...PUSHING THE FRONT THROUGH DEEP SOUTH
TEXAS JUST AFTER MIDNIGHT SUNDAY NIGHT. SHOWERY ACTIVITY WILL
DEVELOP ALONG THE FRONT DURING PASSAGE...WITH COLD NORTHERLY FLOW
IN ITS WAKE. BEHIND THIS FRONTAL PASSAGE...THE MODELS ARE DRIVING
THE CUTOFF LOW ACROSS THE SOUTHERN US LATER MONDAY INTO TUESDAY.
THIS WILL INDUCE COASTAL TROUGHING...WITH SIGNIFICANT OVERRUNNING
DEVELOPING MONDAY INTO TUESDAY. AFTER TUESDAY...MODELS PROGRESS
THE H5 LOW ACROSS THE US...PICKING UP THE COASTAL TROUGH AND
EJECT IT TO THE NE. MODELS ALSO BRING THE NEXT COLD FRONT DIVING
SOUTHWARD DURING THE MIDDLE OF THE WEEK. TIMING IS STILL AN
ISSUE...WITH A FULL DAY DIFFERENCE BETWEEN MODELS CURRENTLY. WILL
HOLD OFF ON INCREASING LATE PERIOD POPS UNTIL BETTER CONSISTENCY
ARRIVES.

MARINE...NOW THROUGH FRIDAY NIGHT... WEAK COLD FRONT MOVES THROUGH
THE COASTAL WATERS THIS MORNING. WINDS ALREADY TURNING EAST WILL
CONTINUE TO BACK NORTHEAST AND INCREASE. MODEST  PRESSURE GRADIENT
TO KICK WINDS UP JUST SHY OF SMALL CRAFT ADVISORY LEVELS THIS
AFTERNOON. SURFACE HIGH PRESSURE SHIFTS EAST AND WINDS VEER
SOUTHEAST SATURDAY AND INCREASE GRADUALLY AS AN UPPER LOW PRESSURE
TROUGH SLOWLY ADVANCES INTO NORTHWEST MEXICO AND SURFACE PRESSURE
BEGIN TO LOWER OVER WESTERN TEXAS AND SIERRA MADRE OF NORTHEAST
MEXICO.

SATURDAY THROUGH MONDAY...SOUTHEAST WINDS CONTINUE AT 10 TO 15KTS
CONTINUE AS FLOW WRAPS INTO THE NEXT COLD FRONT. THE WINDS BRIEFLY
RELAX IMMEDIATELY AHEAD OF THE FRONT ON SUNDAY...WHILE LONG PERIOD
SWELLS REMAIN 3 TO 4 FEET. THE NEXT COLD FRONT IS CURRENTLY
FORECAST TO ARRIVE SUNDAY NIGHT JUST AFTER MIDNIGHT...WITH WINDS
SWITCHING TO THE NORTH AT 20 TO 25 KNOTS. SMALL CRAFT ADVISORIES
ARE LIKELY SUNDAY NIGHT INTO MONDAY BEFORE RELAXING LATE IN THE
AFTERNOON. HIGHER GUSTS ARE NOT CURRENTLY EXPECTED DUE TO THE
WATER TEMPERATURES NOT BEING CONDUCIVE TO LLVL MIXING THIS LATE IN
THE WINTER. SEAS WILL INCREASE TO 6 TO 8 FEET OFFSHORE ON MONDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  69  58  69  61 /  10  10  20  20
BROWNSVILLE          71  58  71  61 /  10  10  20  20
HARLINGEN            70  56  71  60 /  10  10  20  20
MCALLEN              70  58  72  60 /  20  10  20  30
RIO GRANDE CITY      70  58  73  59 /  20  20  20  40
SOUTH PADRE ISLAND  MMM MMM MMM MMM / MMM MMM MMM MMM

&&

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

$$

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