Area Forecast Discussion
Issued by NWS Brownsville, TX

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000
FXUS64 KBRO 170539 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1239 AM CDT SUN AUG 17 2014

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

.AVIATION...HIGH CIRRUS IS WAFTING FROM NORTHEAST TO SOUTHWEST
OVER DEEP SOUTH TEXAS. SURFACE WINDS ARE EXPECTED TO REMAIN AT
MODERATE LEVELS THROUGH THE OVERNIGHT HOURS. TOMORROW...VFR WILL
PREVAIL AS WINDS ONCE AGAIN BECOME BREEZY WITH SCATTERED CLOUDS
IN PLACE. CONDITIONS SIMILAR TO RIGHT NOW ARE EXPECTED SUNDAY
NIGHT.
&&

.PREV DISCUSSION... /ISSUED 1033 PM CDT SAT AUG 16 2014/

DISCUSSION...UPDATED FOR LATEST MARINE DISCUSSION BELOW.

MARINE...WINDS ACROSS THE LOWER TEXAS GULF WATERS HAVE INCREASED
SLIGHTLY THIS EVENING. LATEST MARINE OBSERVATIONS INDICATE
SOUTHEAST WINDS AROUND 19 KNOTS WITH 25 TO 30 KNOTS AT 1000 FEET PER
BRO VAD WIND PROFILE. MODEL GUIDANCE SUGGEST MARGINALLY SMALL
CRAFT CONDITIONS POSSIBLE OVERNIGHT. SO DECIDED TO HOIST A SMALL
CRAFT ADVISORY FOR THE GULF WATERS THROUGH 4 AM.

PREV DISCUSSION... /ISSUED 701 PM CDT SAT AUG 16 2014/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...VFR CONDITIONS WILL PREVAIL ACROSS THE AREA FOR THE
NEXT 24 HOURS. BREEZY SOUTHEAST WINDS THIS EVENING WILL GRADUALLY
DECREASE TO AROUND 10 KNOTS AT BRO/HRL...AND 10 TO 15 KNOTS AT MFE
OVERNIGHT COURTESY OF A LOW LEVEL JET /30 TO 35 KNOTS/ ACROSS THE
REGION. BROAD HIGH PRESSURE ACROSS THE GULF OF MEXICO WILL
INTERACT WITH LOW PRESSURE OVER WEST TEXAS ON SUNDAY RESULTING IN
BREEZY SOUTHEAST WINDS DEVELOPING AROUND 14Z WITH GUSTS AROUND 25
KNOTS IN THE AFTERNOON.

PREV DISCUSSION... /ISSUED 620 PM CDT SAT AUG 16 2014/

DISCUSSION...CURRENT SURFACE OBSERVATIONS INDICATE THAT HEAT
INDICES RANGE FROM 100 TO 105 DEGREES ACROSS MUCH OF DEEP SOUTH
TEXAS THIS EVENING. THEREFORE...SINCE HEAT INDICES HAVE FALLEN BELOW
ADVISORY CRITERIA...THE HEAT ADVISORY PREVIOUSLY IN EFFECT FOR
PORTIONS OF THE COASTAL COUNTIES INTO HIDALGO COUNTY HAS BEEN
CANCELLED. ALL UPDATED TEXT PRODUCTS HAVE BEEN SENT.

PREV DISCUSSION... /ISSUED 238 PM CDT SAT AUG 16 2014/

SHORT TERM /NOW THROUGH SUNDAY NIGHT/...
EARLY AFTERNOON WATER VAPOR DEPICTS AN AREA OF HIGH PRESSURE ACROSS
THE DESERT SOUTHWEST AND ANOTHER AREA OF HIGH PRESSURE OFF THE
EASTERN SEABOARD. RIDGING STRETCHED IN BETWEEN THESE TWO AREAS
ACROSS US AND INTO THE GULF OF MEXICO AND SOUTHEAST CONUS. A S/W
TROUGH WAS MOVING ACROSS THE MISSOURI VALLEY AND PROVIDE A
`WEAKNESS` IN BETWEEN THE TWO HIGHS THROUGH THE SHORT TERM. A MINOR
WAVE WILL ALSO MOVE THROUGH CENTRAL AND NORTHERN TEXAS AND PROVIDE A
SHOT OF PRECIPITATION SUNDAY AND SUNDAY NIGHT ACROSS THAT AREA BUT
WILL REMAIN NORTH OF OUR AREA.

LEE TROUGHING WILL CONTINUE TO BE LOCATED TO OUR WEST IN NORTHERN
MEXICO INTO WEST TEXAS. STRONGER WINDS TODAY (GUSTS TO 25-30 MPH)
WILL CONTINUE THE REST OF THE AFTERNOON BEFORE DECREASING AFTER
SUNSET. 925MB WINDS STRENGTHEN OVER NIGHT WITH A SWATH OF 40 KNOT
WINDS ACROSS THE CENTRAL AND WESTERN PORTIONS OF THE AREA. THESE
WILL MIX DOWN SUNDAY AND OFFER A LITTLE STRONGER WINDS COMPARED TO
TODAY ACROSS MORE OF THE AREA. BELIEVE THE STRONGEST WINDS WILL
REMAIN IN THE MIDDLE AND LOWER VALLEY WHERE PRESSURE GRADIENT IS
STRONGEST. 25-30 MPH GUSTS LOOK COMMON ACROSS THE AREA WITH A FEW
HIGHER GUSTS POSSIBLE.

ISSUED HEAT ADVISORY FOR THE COASTAL COUNTIES PLUS HIDALGO COUNTY
EARLIER THIS MORNING THROUGH 7 PM TONIGHT. AFTER LOOKING AT 12Z
DATA...STILL BELIEVE ISOLATED AREAS WILL MEET CRITERIA BUT MAY NOT
BE AS WIDESPREAD AS EARLIER THOUGHT. DEWPOINTS HAVE MIXED A LITTLE
LOWER THAN FORECAST AND THAT MAY BE THE DIFFERENCE FOR MEETING THE
CRITERIA. NEVERTHELESS...STILL WILL BE HOT AND MUGGY THIS AFTERNOON
AND FOLKS SHOULD STILL TAKE HEAT PRECAUTIONS (FREQUENT
BREAKS...HYDRATE...SEEK SHADE...ETC). HIGHS WILL BE NEAR OF EXCEED
100 DEGREES ACROSS A VAST MAJORITY OF THE AREA. HIGHS TOMORROW WILL
BE COMPARABLE TO TODAY WITH DEWPOINTS A TICK LOWER WHICH WILL
PRECLUDE AN ADVISORY FOR TOMORROW.  /55/

LONG TERM /MONDAY THROUGH SATURDAY/...
AT THE START OF THE LONG TERM...OUR AREA REMAINS JUXTAPOSED BETWEEN
TWO CENTERS OF RIDGING.  ONE CENTER WAS LOCATED NEAR THE FOUR
CORNERS...WHILE THE OTHER WAS ESSENTIALLY AN EXTENSION OF THE
SUBTROPICAL RIDGE INTO THE NORTHERN GULF OF MEXICO.

THE WEAKNESS BETWEEN THE RIDGES (FOR LACK OF A BETTER TERM) IS
EXPECTED TO DAMPEN AND SHIFT EAST ACROSS THE TENNESSEE VALLEY TOWARD
MID-WEEK.  THIS WILL ALLOW RIDGING TO AMPLIFY ACROSS OUR REGION AS
THE SUBTROPICAL RIDGE BUILDS WESTWARD...AND LARGELY MERGES WITH
RIDGING OVER THE DESERT SOUTHWEST.

SO...IT LOOKS LIKE MONDAY AND TUESDAY SHOULD REMAIN DRY...DESPITE
THE WEAKNESS IN THE RIDGE ALMOST OVERHEAD.  FORECAST SOUNDINGS
INDICATE A RELATIVELY DRY PROFILE THROUGH THE BOUNDARY LAYER...WITH
PRECIPITABLE WATER VALUES EXPECTED TO BE JUST SHY OF NORMAL FOR
AUGUST.  A BIG STORY WILL LIKELY REMAIN THE HEAT...AS AFTERNOON HEAT
INDICES LIKELY REMAIN NEAR 110 DEGREES OR SO.  A CONTINUED STRONG
PRESSURE GRADIENT WILL ALSO ALLOW BREEZY CONDITIONS TO CONTINUE.

THINGS MAY START TO CHANGE A BIT BY MID-WEEK THOUGH...AS A
WESTWARD-MOVING TROPICAL WAVE STARTS TO HEAD OUR WAY.  AN INCREASE
IN BOUNDARY LAYER MOISTURE IS EXPECTED TO BE ASSOCIATED WITH THIS
DISTURBANCE...WHICH MAY LEAD TO AN INCREASE IN CONVECTIVE ACTIVITY
ACROSS PARTS OF THE FORECAST AREA.  RIGHT NOW...EVEN WITH SLIGHTLY
(EMPHASIS ON SLIGHTLY) BETTER SYNOPTIC SCALE FORCING AND BOUNDARY
LAYER MOISTURE...THE GREATEST COVERAGE OF SHOWERS OR STORMS SHOULD
REMAIN OFFSHORE DURING THE PRE-DAWN HOURS.

LOW-LEVEL MOISTURE PROFILES ARE EXPECTED TO DEEPEN AS WE HEAD TOWARD
NEXT WEEKEND...THANKS TO A PERSISTENT EAST TO SOUTHEAST FLOW.
PRECIPITABLE WATER VALUES MAY RISE TOWARD THE 2 INCH MARK
SATURDAY...WITH SURFACE-BASED CAPE VALUES OF 3000 JOULES/KG
(GIVE-OR-TAKE) ACROSS THE VALLEY IN A LARGELY UNCAPPED ENVIRONMENT.
WITH WINDS THROUGH THE BOUNDARY LAYER EXPECTED TO BACK SLIGHTLY...A
MORE ACTIVE SEABREEZE WILL BE POSSIBLE AND WE COULD SEE A BETTER
CONVECTIVE COVERAGE.  FOR NOW...I WILL REMAIN ON THE CONSERVATIVE
SIDE AND KEEP PRECIPITATION PROBABILITIES IN SLIGHT CHANCE
TERRITORY...WITH A GREATER COVERAGE OFFSHORE.  /53/

MARINE...

NOW THROUGH SUNDAY NIGHT...
BREEZY CONDITIONS WILL CONTINUE THROUGH THE SHORT TERM PERIOD. SCEC
CONDITIONS ARE UP FOR ALL LOWER TEXAS COASTAL WATERS AS LOW PRESSURE
TO OUR WEST CONTINUES TO INTERACT WITH HIGH PRESSURE OVER THE GULF.
WINDS WILL DECREASE TONIGHT OVER THE LAGUNA ENOUGH TO DROP SCEC BY
LATE EVENING. WINDS WILL MAINTAIN OR SLIGHTLY INCREASE ON THE
OFFSHORE WATERS TO CONTINUE SCEC CONDITIONS. A REPEAT OF TODAY IS IN
STORE FOR SUNDAY. /55/

MONDAY THROUGH THURSDAY...
A PERSISTENT PRESSURE GRADIENT WILL LIKELY RESULT IN SMALL CRAFT
EXERCISE CAUTION HEADLINES CONTINUING INTO THE FIRST HALF OF THE
UPCOMING WORKWEEK.  SOUTHEAST WINDS 15 TO 20 KNOTS WILL LIKELY
CONTINUE...WITH SEAS GENERALLY REMAINING AROUND 4 FEET.  PRIMARY
WAVE PERIODS ARE EXPECTED TO AVERAGE 5 TO 6 SECONDS.  /53/
&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 4 AM CDT EARLY THIS MORNING FOR
     GMZ150-155-170-175.
&&

$$

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