Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 271751
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1151 AM CST FRI FEB 27 2015

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

&&

.AVIATION...HIGH CLOUDS ARE EXPECTED TO DECREASE AS THE UPPER JET
SHIFTS DOWNSTREAM. COLD AIR BEHIND A COLD FRONT IS FILTERING INTO
THE WESTERN PORTION OF THE CWA THIS MORNING...AND THE ISENTROPIC
LIFT WILL SUPPORT LOWERING CEILINGS...WITH LIGHT RAIN AND DRIZZLE
STARTING TO MOVE INLAND. THIS RAIN WILL GRADUALLY BE ON THE INCREASE
DURING THE DAY. A VERY SHARP TEMPERATURE GRADIENT WITH A WARM AIR MASS
FROM HWY 77 EAST AND COLDER WEST OF 77 ASOCIATED TO THIS COLD FRONT.
AS THE COASTAL TROUGH STRENGTHENS THE WINDS SHIFT MORE NORTHERLY LATER
INTO TONIGHT. THIS TROUGH WILL EVENTUALLY BE LIFTED NORTHEAST WITH COLD
AIR MASS FROM THE WEST TAKING CONTROL AND FILTERING IN THROUGH THE AREA.
THE WINDS WILL BEGIN TO SHIFT NORTHWEST CLOSER TO MIDNIGHT AND WESTERLY
INTO SATURDAY.

&&

.PREV DISCUSSION... /ISSUED 1035 AM CST FRI FEB 27 2015/

DISCUSSION...THE COLD AIR CONTINUES TO MOVE SOUTH ACROSS
THE CWA ESPECIALLY TOWARDS THE WESTERN PORTION OF THE CWA.
THIS HAS SHIFTED WINDS MORE NORTHWEST KEEPING TEMPERATURES
COOLER THAN EXPECTED. KEPT A NORTH TO NORTHWEST FLOW ACROSS
THE AREA WITH A SHARP TEMPERATURE GRADIENT FROM WEST TO EAST.
LOWER HIGH TEMPERATURES A FEW DEGREES MORE TOWARDS THE WEST
AND WITH A EASTERLY FLOW DEVELOPING KEPT WARMER TEMPERATURES
IN THE MID 60S. CHANCE OF RAIN REMAINS THE SAME AND THERE ARE
NO OTHER CHANGES DONE TO THE FORECAST AT THIS TIME.

PREV DISCUSSION... /ISSUED 547 AM CST FRI FEB 27 2015/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...HIGH CLOUDS ARE EXPECTED TO DECREASE AS THE UPPER JET
SHIFTS DOWNSTREAM. COLD AIR BEHIND A COLD FRONT IS FILTERING INTO
THE CWA THIS MORNING...AND THE ISENTROPIC LIFT WILL SUPPORT
LOWERING CEILINGS...WITH LIGHT RAIN AND DRIZZLE POSSIBLE LATER IN
THE DAY. LIGHT TO MODERATE NORTHEAST WINDS WILL BECOME VERY LIGHT
THIS EVE...BUT WILL THEN PICK UP AGAIN SLIGHTLY AFTER MIDNIGHT.
CEILINGS SHOULD LOWER TO MVFR BY MID MORNING AND THEN TO IFR LATER
TODAY. THE GUIDANCE VARIES A LITTLE FOR THIS EVENING...WITH THE
GFS KEEPING CEILINGS A CATEGORY HIGHER THAN THE NAM...BUT MVFR IS
THE MIDDLE GROUND FOR NOW.

 &&

PREV DISCUSSION... /ISSUED 254 AM CST FRI FEB 27 2015/

SHORT TERM /NOW THROUGH SATURDAY/...A COLD FRONT IS WORKING ITS
WAY THROUGH THE CWA THIS MORNING...WITHOUT TOO MUCH FANFARE.
SOUTHERN EDGE AND RR QUAD OF AN UPPER JET STREAK RESULTED IN A
RIBBON OF UPPER CLOUDS STILL OVER THE SOUTHEASTERN CORNER OF THE
CWA BUT THAT SHOULD FADE TODAY AS THICKER LOW CLOUDS TAKE OVER.
LOW CLOUDS ARE THICKENING FROM WEST TO EAST. NORTHEAST WINDS THAT
WERE ALREADY IN PLACE ARE RECEIVING SOME REINFORCEMENT AND DEW
POINTS ARE DECREASING BEHIND THE FRONT. LOOKING FOR A
COOL...CLOUDY DAY ACROSS DEEP SOUTH TEXAS AND THE RGV TODAY WITH A
RANGE OF HIGH TEMPS FROM THE UPPER 40S FAR WEST AND NORTH TO THE
LOWER 60S FOR CAMERON AND WILLACY COUNTIES. LIGHT RAIN AND DRIZZLE
CHANCES WILL INCREASE LATER TODAY AND TONIGHT AS THE COOLER AIR
BECOMES ESTABLISHED. LOW TEMPS TONIGHT WILL BE MAINLY IN THE 40S
AND 50S WITH LIGHT WINDS AS HIGH PRESSURE SPREADS OVER THE AREA.
LOOKS LIKE THE HIGH PRESSURE WILL THEN SHIFT EAST IN SHORT ORDER.
WINDS WILL VEER TO EAST BY SATURDAY AND THE RETURN FLOW WILL
SUPPORT HIGH TEMPS IN THE 60S...THOUGH AMPLE CLOUD COVER WILL
CONTINUE AND A MID LEVEL FLOW THAT WILL BACK FROM WEST TO
SOUTHWEST WILL HELP ENSURE THAT OVERRUNNING PERSISTS.

LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...OVERRUNNING LIGHT
RAIN CHANCES ACROSS DEEP SOUTH TEXAS AND THE RGV WILL COME TO AN
END SUNDAY AS COASTAL TROUGHING WEAKENS AND A WARM FRONT LIFTS
NORTHWARD. WINDS BECOME SOUTHEASTERLY BY SUNDAY MORNING AND
MOISTURE DECREASES. COLD AIR IS SHUNTED NORTH AND EAST FOR THE
START OF THE WORK WEEK WITH 850MB TEMPERATURES RISING FROM 13C
SUNDAY MORNING TO 22C BY TUESDAY NIGHT. 700MB SOUTHWESTERLIES
SPREAD OVER THE AREA BEGINNING MONDAY NIGHT. WHAT THIS MEANS IS
HIGH TEMPERATURES MONDAY AND TUESDAY WILL BE IN THE 80S WITH LOW
90S OUT WEST WHERE MID LEVEL DRY AIR DUE TO THOSE AFOREMENTIONED
SOUTHWESTERLIES WILL BE MIXED DOWN.

AN UPPER TROF WILL MOVE OVER THE WESTERN CONUS AND FOUR CORNERS
THROUGH TUESDAY. PRESSURE FALLS AHEAD OF THIS FEATURE WILL INDUCE
LEE TROUGHING ACROSS THE ROCKIES SOUTHWARD INTO THE SIERRA MADRES.
THIS WILL HELP RATCHET UP THE SOUTHERLY SURFACE WINDS MONDAY AND
TUESDAY AS WELL. SURFACE LOW PRESSURE WILL HEAD OUT OF THE HIGH
PLAINS TUESDAY AND DRAG A COLD FRONT INTO CENTRAL AND SOUTHERN
TEXAS WEDNESDAY. WIDESPREAD STRATUS ON A 40KT LOW LEVEL JET WILL
KEEP THE AREA MOSTLY CLOUDY THROUGH THE DAY WHICH WILL HOLD HIGH
TEMPERATURES DOWN INTO THE LOW 80S. TIMING DIFFERENCES EXIST
BETWEEN THE GFS/ECMWF CONCERNING THE PASSAGE OF THE FRONT WITH GFS
A LITTLE FASTER BRINGING THE FRONT THROUGH WEDNESDAY AND THE ECMWF
AT WEDNESDAY NIGHT AND THURSDAY. DESPITE THE TIMING DIFFERENCES
EXPECT STRONG NORTHERLY WINDS AND COOLER TEMPERATURES TO ROUND OUT
THE WORK WEEK. AS FAR AS POPS GO ASSOCIATED WITH THE FRONT LOOKS
LIKE CAPPING WILL BE STRONG AND LIMIT MOST PRECIPITATION TO WELL
OFFSHORE. BOTH ECMWF AND GFS HINT AT WEAK COASTAL TROUGHING FRIDAY
WITH A SLIGHT CHANCE FOR LIGHT RAIN ALONG AND EAST OF HWY 77.

MARINE /NOW THROUGH THROUGH SATURDAY/...STRONG HIGH PRESSURE
OVER THE PLAINS WILL EXTEND SOUTH OVER THE NORTH GULF AND WILL SET
UP MDT TO FRESH EAST NORTHEAST WINDS...BUT PERHAPS OF MORE
SIGNIFICANCE WILL BE THE LONG FETCH ACROSS THE NORTH GULF...WHICH
WILL SUPPORT ELEVATED SEAS DUE TO A SWELL COMPONENT. THE ONGOING
SMALL CRAFT ADVISORY FOR THE GULF WILL THUS PERSIST THROUGH THE
SHORT TERM. WAVE HEIGHTS OF 7 TO 9 FEET WILL PERSIST ON THE OPEN
GULF THROUGH SATURDAY AND INTO THE LONG TERM.

SATURDAY NIGHT THROUGH TUESDAY...MODERATE TO STRONG EAST WINDS
SATURDAY NIGHT WILL WEAKEN AND TURN MORE SOUTHEASTERLY SUNDAY AS A
WARM FRONT MOVES NORTHWARD THROUGH THE COASTAL WATERS. SMALL CRAFT
ADVISORIES WILL BE ONGOING INTO THE LONG TERM AND WILL BE NEED
THROUGH SUNDAY AS SEA HEIGHTS WILL REMAIN AROUND 7 FEET THROUGH
SUNDAY AFTERNOON. WINDS AND SEAS BECOME MORE MODERATE MONDAY WITH
CONDITIONS DETERIORATING MONDAY NIGHT AND TUESDAY AS LOW PRESSURE
DEEPENS TO OUR WEST AND SOUTHEASTERLY WINDS STRENGTHEN. SMALL
CRAFT ADVISORIES WILL BE LIKELY MONDAY NIGHT INTO TUESDAY.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 3 AM CST SATURDAY FOR GMZ150-155-170-
     175.

&&

$$

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