246
FXUS64 KBRO 211137 AAA
AFDBRO
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
637 AM CDT SUN OCT 21 2018
DISCUSSION
UPDATED FOR LATEST AVIATION DISCUSSION BELOW.
AVIATION
MUCH BALLYHOOED RAIN STARTING TO STREAM ACROSS
CAMERON COUNTY THIS MORNING, REINFORCING DEGRADED AVIATION
CONDITIONS AT THE TAF SITES, ESPECIALLY BRO AND HRL. LOOK FOR
IFR/MVFR CEILINGS AND ALSO PERIODIC VISIBILITY RESTRICTIONS IN
MIST AND PATCHES OF RAIN. A COASTAL TROUGH REMAINS IN PLACE, WITH
SOME MODELS HINTING AT A SHARPENING ALONG THE TROUGH AXIS AND A
WESTWARD TOPPLING OF THE APEX OVER THE LOWER VALLEY, MAINTAINING
LOWER CEILINGS AND ELEVATED/INCREASING RAIN CHANCES THROUGH THE
DAY AND INTO THIS EVENING. SURFACE WINDS WILL BE MOSTLY MODERATE
NORTH.
PREV DISCUSSION
/ISSUED 429 AM CDT SUN OCT 21 2018/
SHORT TERM (NOW THROUGH MONDAY): WITH THE MODELS MOSTLY HOLDING
THE COASTAL TROUGH OFFSHORE TODAY, THE THREAT OF FLASH FLOODING
ACROSS THE AREA HAS DIMINISHED. MOST QPF ESTIMATES ARE BELOW FF
GUIDANCE. THUS, TRIMMED THE ONGOING WATCH BACK A SKOSH, CUTTING OUT
BROOKS COUNTY, AND PROBABLY COULD HAVE TRIMMED MORE, BUT OPTED TO
LET THE NEXT SHIFT HAVE A LOOK AT THE SITUATION. THAT SAID, RAIN
CHANCES THE NEXT 36 HOURS REMAIN FAIRLY HIGH, BUT ANTICIPATE MORE OF
THE LIGHT RAIN TYPE. THAT'S NOT TO SAY ISOLATED MODERATE TO HEAVY
SLOW MOVING RAINERS COULDN'T TRACK ACROSS THE SOUTHEAST CORNER OF
THE CWA, PRODUCING LOCALIZED FLOODING HERE AND THERE. HIGH TEMPS IN
THE SHORT TERM WILL BE HELD IN THE 60S AND 70S UNDER MOSTLY CLOUDY
TO OVERCAST SKIES, WITH OVERNIGHT LOWS IN THE 50S AND 60S. WINDS
WILL BE LIGHT TO MODERATE FROM THE NORTH.
THE APEX OF THE OFFSHORE CONVERGENT ZONE WILL NOSE FARTHER NORTH ON
MONDAY, TAKING MUCH OF THE PRECIP POTENTIAL WITH IT, LEAVING WEAK
LOW PRESSURE JUST OFFSHORE. THE THREAT OF HEAVY RAINFALL WILL
FURTHER DIMINISH, THOUGH MOISTURE WILL REMAIN ELEVATED WITH
PRECIPITABLE WATER OVER TWO INCHES AND ENOUGH OF A LOW LEVEL
INVERSION TO KEEP MOSTLY CLOUDY TO OVERCAST SKIES IN THE SHORT TERM
FORECAST. MOISTURE FROM HURRICANE WILLA IN THE EASTERN PACIFIC MAY
TRACK CLOSE TO (RGV PLAINS) OR POSSIBLY OVER THE UPPER VALLEY WITH
TIME, BUT UNCERTAIN AS TO ANY RAIN POTENTIAL FROM THAT SOURCE IN THE
SHORT TERM RIGHT NOW.
COASTAL FLOODING: BEACH CAMS SHOW BEACH RUN UP AT HIGH TIDE, AND
WITH FRESH NORTHEAST WINDS AND BUILDING SEAS FORECAST FOR TODAY,
WITH TIDES RUNNING A FOOT ABOVE ASTRONOMICAL, OPTED TO POST A
COASTAL FLOOD STATEMENT THROUGH HIGH TIDE AT AROUND 1:30 PM THIS
AFTERNOON.
LONG TERM (MONDAY NIGHT THROUGH SATURDAY): LOOKS LIKE UNSETTLED
WEATHER WILL REMAIN IN THE PICTURE THROUGH THE MIDDLE PART OF THE
WEEK, THEN AN INCREASINGLY DRIER, MORE STABLE, AND SOMEWHAT WARMER
PATTERN KICKS IN FOR THE LATTER PORTION OF THE WEEK.
00Z RUNS OF GFS AND NAM BOTH A LITTLE MORE STUBBORN IN HANGING
ON/REFORMING THE COASTAL TROUGH/LOW A LITTLE LONGER THAN PRIOR
RUNS. MONDAY NIGHT, THE ATMOSPHERIC COLUMN IS PROGGED TO REMAIN
NEARLY SATURATED, BUT WITH LITTLE UPPER-LEVEL SUPPORT, QPF REMAINS
ON THE MODEST SIDE (ONLY A 0.1" OR SO) EVEN INTO TUESDAY. LOOKS
LIKE A COOL START TO THE LONG-TERM AS WELL, IN ADDITION TO THE
DAMPNESS, AS THE SURFACE TROUGH MAINTAINS N-NW WINDS AT THE
SURFACE, WITH MORNING LOWS RANGING FROM THE MID-50S FAHRENHEIT NW
TO THE LOW 60S NEAR BROWNSVILLE. GULF OF MEXICO 500-MB HIGH
"TRIES" TO BACK INTO THE AREA TUESDAY, BUT HAS A TOUGH TIME MAKING
HEADWAY AS THE TROUGHING OVER THE GREAT BASIN PHASES WITH THE
REMNANT UPPER CIRCULATION FROM CURRENT TROPICAL STORM WILLA TO
MAINTAIN LIGHT SW FLOW. THUS, SHOWER CHANCES CONTINUE.
BOTH GFS AND ECMWF INDICATE THAT THE WILLA REMNANT MOISTURE/UPPER
CIRCULATION WILL BE CAUGHT UP IN THE MID-LATITUDE FLOW AND MOVE UP
OVER SOUTHERN/CENTRAL TEXAS. SOME DIFFERENCES IN TIMING AND
AMPLITUDE OF THE PROGRESSION, THOUGH. GFS MOVES WHAT'S LEFT OF
WILLA QUICKLY ACROSS SOUTH TEXAS ON WEDNESDAY, WITH DRIER AIR
QUICKLY MOVING IN BEHIND IT OVERNIGHT. ECMWF DAMPENS IT OUT MORE,
WITH A SLOWER PROGRESSION...BUT WITH A PATH MORE OVER DEEP SOUTH
TEXAS...FROM ROUGHLY 06-18Z THURSDAY. BOTH MODELS, HOWEVER, KEEP
THE BULK OF THE PRECIPITATION TO THE NORTH OF OUR CWA. DIDN'T MAKE
MANY CHANGES TO THE POP'S IN THIS PERIOD, DUE TO THE TIMING
UNCERTAINTY. SCATTERED SHOWERS WITH A FEW THUNDERSTORMS WOULD SEEM
TO BE A GOOD BET.
ONCE THIS FEATURE DOES MOVE THROUGH, PRECIPITATION CHANCES ARE
EXPECTED TO EFFECTIVELY END (ESPECIALLY COMPARED WITH THOSE OF
LATE), AS A MID- LATITUDE TROUGH TO THE NORTH FLATTENS THE FLOW
ALOFT TO ZONAL BY FRIDAY. PRECIPITABLE WATER TUMBLES BACK DOWN TO
AROUND 1.5" OR SO. FURTHER DRYING IS INDICATED FOR NEXT WEEKEND,
AS VERY DRY NW FLOW ALOFT ARRIVES AFTER A SHEAR AXIS MOVES
THROUGH ON SATURDAY.
TEMPERATURES SHOULD MODERATE SOME AFTER TUESDAY, BUT STILL REMAIN
WELL BELOW NORMAL THROUGH AT LEAST THURSDAY, WITH MID-UPPER 70S
(NOT BAD!) COMMON IN THE MID/LOWER RGV. IF THE ADVERTISED DRYING
LATE IN THE WEEK DOES OCCUR, TEMPS COULD CLIMB BACK TO NEAR OR
JUST SLIGHTLY ABOVE NORMAL. LEANED ON THE WARMER SIDE OF GUIDANCE
FOR NEXT SATURDAY AS THE DRYING PATTERN LOOKS REALISTIC.
MARINE (NOW THROUGH MONDAY): COASTAL TROUGHING ALONG A WEAK STATIONARY
FRONT IS SUPPORTING DEGRADED MARINE CONDITIONS IN THE SHORT TERM.
THE TIGHTER PRESSURE GRADIENT BETWEEN THE TROUGH AND HIGHER PRESSURE
OVER THE NORTHWEST GULF IS PRODUCING FRESH TO STRONG NORTHEAST
WINDS, WHICH SHOULD CONTINUE THROUGH THE NEXT 36 HOURS, ALONG WITH
ELEVATED WAVE HEIGHTS. SMALL CRAFT SHOULD EXERCISE CAUTION TO LOW
END SMALL CRAFT ADVISORY CONDITIONS WILL CONTINUE ON THE LAGUNA,
WITH MORE CERTAIN SMALL CRAFT ADVISORY CONDITONS ON THE GULF WATERS.
IT LOOKS LIKE THE FRONTAL BOUNDARY WILL PUSH NORTH BY MONDAY, BEING
REPLACED OFFSHORE BY AN AREA OF LOW PRESSURE, ULTIMATELY ALLOWING
FOR SOMEWHAT WEAKER WINDS.
MONDAY NIGHT THROUGH FRIDAY: SMALL CRAFT ADVISORY CONDITIONS (BOTH
WIND AND SEAS) MAY TO BE ONGOING MONDAY EVENING FOR THE GULF
WATERS, AS STRONGER NE WINDS NORTH OF THE ONCE-AGAIN REINVIGORATED
COASTAL TROUGH WILL BE IN PLACE. SAID SURFACE LOW IS FORECAST TO
FINALLY LIFT AWAY FROM THE LOWER TEXAS COAST AS TUESDAY WEARS ON.
AGITATED SEAS PROBABLY WILL BE SLOW TO SUBSIDE, HOWEVER, WITH
HAZARDOUS CONDITIONS LINGERING INTO TUESDAY NIGHT. A MORE MODERATE
NORTHERLY WIND, AND CONSEQUENTLY MODERATE SEAS OF 3-5 FT., SHOULD
PREVAIL FROM WEDNESDAY THROUGH FRIDAY.
BRO WATCHES/WARNINGS/ADVISORIES
TX...FLASH FLOOD WATCH THROUGH MONDAY MORNING FOR TXZ251-253>257-351-
353.
GM...SMALL CRAFT ADVISORY FOR WINDS UNTIL MIDNIGHT CDT TONIGHT FOR
GMZ130-132-135.
SMALL CRAFT ADVISORY UNTIL 1 PM CDT MONDAY FOR GMZ150-155-170-
175.
THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
HTTP://WEATHER.GOV/RGV
54/53
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page