Area Forecast Discussion
Issued by NWS Brownsville, TX

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000
FXUS64 KBRO 160536 AAB
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1236 AM CDT THU APR 16 2015

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

&&

.AVIATION...MID TO HIGH CLOUDS ARE STILL STREAMING ACROSS THE CWA
IN THE SOUTHWEST FLOW ALOFT...WITH MULTI-LAYERED LOW CLOUDS AT THE
TAF SITES...ONLY MFE IS CURRENTLY MVFR. GUIDANCE SUGGESTS A MIX OF
MVFR AND VFR WITH CEILINGS FILLING AND FADING IN THE MVFR BRACKET.
LIGHT TO MODERATE SOUTHEAST WINDS WILL KEEP THE MOISTURE ADVECTING
INTO THE AREA TODAY...SUPPORTING THE LOWER CLOUD LAYERS. THE LOSS
OF THE CAP TODAY WITH DAYTIME HEATING WILL PROMOTE SHOWER AND TSTM
ACTIVITY IN THE AREA...WITH TEMPO IFR FOR CIGS POSSIBLE. A BIT OF
FOG AND EVEN SOME IFR CEILINGS MAY DEVELOP NEAR THE COAST TONIGHT
AS MOISTURE LEVELS REMAIN ELEVATED AND FOG IS SUPPORTED BY WETTED
SURFACES. SOUTHEAST WINDS WILL CONTINUE BUT SHOULD BE LOW ENOUGH
TO ALLOW COASTAL FOG TO DEVELOP TONIGHT.

&&

.PREV DISCUSSION... /ISSUED 657 PM CDT WED APR 15 2015/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...SATELLITE IMAGES AND SURFACE OBSERVATIONS INDICATE LOW
CLOUDS ACROSS DEEP SOUTH TEXAS THIS EVENING. CEILINGS RANGE FROM
AROUND 2000 FEET AT MFE TO 3200 FEET AT HRL. EXPECT A MIX OF MVFR
TO LOW END VFR CEILINGS THIS EVENING...WIDESPREAD MVFR CONDITIONS
WILL DEVELOP TONIGHT WITH ABUNDANT LOW TO MID LEVEL MOISTURE OVER
THE REGION. THIS WILL RESULT IN LOW CLOUDS AND PATCHY FOG
DEVELOPING LATE TONIGHT INTO THURSDAY MORNING. A WEAK STATIONARY
FRONTAL BOUNDARY CURRENTLY ACROSS THE NORTHWEST GULF OF MEXICO
EXPECTED TO LIFT NORTHWARD AS A WEAK WARM FRONT LATER TONIGHT INTO
THURSDAY. ISOLATED SHOWERS MAY DEVELOP ALONG THIS BOUNDARY TOWARDS
DAYBREAK WITH SCATTERED SHOWERS AND THUNDERSTORMS ON THURSDAY.
WILL CONTINUE TO MENTION VCSH FROM 12Z THRU MID AFTERNOON THURSDAY
AS MOST OF THE CONVECTION SHOULD REMAIN NORTH OF THE VALLEY TAF
SITES.

PREV DISCUSSION... /ISSUED 321 PM CDT WED APR 15 2015/

SHORT TERM /NOW THROUGH THURSDAY NIGHT/...IT APPEARS THE CLOUD
COVER ACROSS THE CWA THIS AFTERNOON IS LIMITING CONVECTION FROM
DEVELOPING AS THE CLOUD COVER CONTINUES TO LIMIT DIURNAL HEATING.
SATELLITE AND RADAR IMAGES INDICATE SHOWERS AND THUNDERSTORMS
CONTINUE TO DEVELOP ACROSS THE MEXICAN PLATEAU AND WELL OFFSHORE
THE LOWER TEXAS COAST. A WEAK STATIONARY FRONTAL BOUNDARY ACROSS
THE NORTHWEST GULF OF MEXICO IS EXPECTED TO LIFT NORTHWARD AS A
WEAK WARM FRONT TONIGHT. THIS BOUNDARY MAY PROVIDE A FOCUS FOR
SHOWERS AND THUNDERSTORMS TO DEVELOP ACROSS PORTIONS OF THE RIO
GRANDE VALLEY AND THE NORTHERN RANCHLANDS BUT WITH THE LOSS OF
DIURNAL HEATING WILL ONLY MENTION A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS FOR TONIGHT.

A 500MB LOW ACROSS THE SOUTHWEST UNITED STATES THURSDAY WILL PROVIDE
A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS FOR DEEP SOUTH TEXAS
THURSDAY INTO THURS NIGHT AS DIFFLUENCE INCREASES ACROSS THE
STATE THURS AFTERNOON INTO THURS EVENING. IN ADDITION...LOW TO MID
LEVEL MOISTURE WILL CONTINUE TO INCREASE AS WARM AIR ADVECTION
CONTINUES TO INCREASE IN THE WAKE OF THE WEAK WARM FRONT MOVING
NORTHWARD TONIGHT INTO THURS MORNING. THE FRONTAL BOUNDARY WILL BE
THE INITIAL FOCUS FOR CONVERGENCE THURS MORNING SO RAIN CHANCES
WILL INCREASE THURS MORNING INTO THURS AFTERNOON AS THE BOUNDARY
LIFTS NORTHWARD. WITH THE INCREASING SURFACE INSTABILITY AND
FAVORABLE FORCING ALOFT...WILL GO AHEAD AND MENTION SOME STORMS
MAY BE SEVERE THURS AFTERNOON INTO THURS EVENING. IN
ADDITION...WILL MENTION HEAVY RAINFALL WITH THUNDERSTORMS THURS
AFTERNOON THROUGH THURS NIGHT AS PRECIPITABLE WATER VALUES
INCREASE TO NEAR 1.8 INCHES THURS AFTERNOON.

LONG TERM /FRIDAY THROUGH TUESDAY/...ACTIVE SPRINGTIME PATTERN
STILL ON TRACK TO CONTINUE INTO THE UPCOMING WEEKEND...WITH A
DAILY RISK FOR STRONG TO SEVERE THUNDERSTORMS AND FLASH FLOODING.

UPPER TROUGH DIVING INTO THE FOUR CORNERS REGION WILL CONTINUE TO
HAVE DIVERGENCE AHEAD OF IT...WITH CONTINUOUS IMPULSES ROTATING
THROUGH THE REGION FROM THE SOUTHWEST AROUND THE BOTTOM OF THE
TROUGH. WITH AN ASSOCIATED JET STREAK ACROSS CENTRAL MEXICO...WE
WILL CONTINUE TO SEE REASONABLE LARGE-SCALE ASCENT THROUGH THE
WEEKEND. ADD IN A GOOD SELY FLOW AT LLVLS AND DEEPER
MOISTURE...AND YOU HAVE THE POTENTIAL FOR THUNDERSTORMS TO BECOME
STRONG TO SEVERE FRIDAY AND AGAIN SATURDAY. MAIN ISSUE WITH FRIDAY
WILL BE IF ENOUGH THUNDERSTORM ACTIVITY IS SEEN ON THURSDAY TO
STABILIZE THE ATMOSPHERE FOR A GOOD 12 TO 18 HOURS. MODELS ARE
STILL A BIT DIFFERING ON SUNDAY AND MONDAY...WITH THE POSSIBILITY
THAT DRIER AIR MAY ENTRAIN INTO THE REGION ALOFT...CREATING A MUCH
STRONGER CAPPING INVERSION. WILL NEED TO MONITOR THESE DAYS FOR
INCREASED POTENTIAL.

MARINE...
TONIGHT THROUGH THURSDAY NIGHT...SEAS WERE NEAR 2 FEET WITH EAST
WINDS NEAR 14 KNOTS AT BUOY020 THIS AFTERNOON. LIGHT TO MODERATE
EAST WINDS WILL VEER TO THE SOUTHEAST TONIGHT AS A WEAK STATIONARY
FRONT ACROSS THE NORTHWEST GULF OF MEXICO MOVES NORTHWARD AS A
WEAK WARM FRONT. LIGHT TO MODERATE SOUTHEAST WINDS WILL PREVAIL
ACROSS THE WESTERN GULF OF MEXICO THURSDAY AND INCREASE THURS
NIGHT AS THE PRESSURE GRADIENT INCREASES ACROSS THE LOWER TEXAS
COAST.

FRIDAY THROUGH SUNDAY...MARINE CONDITIONS WILL REMAIN STABLE
THROUGH THE PERIOD...WITH SEAS OF 3 TO 4 FEET AND SOUTHEAST FLOW
10 TO 15 KNOTS EACH DAY. THE MAIN FORECAST ISSUE IS THE AMOUNT OF
THUNDERSTORM ACTIVITY POSSIBLE EACH DAY...ESPECIALLY ON FRIDAY.
ANY THUNDERSTORM ACTIVITY WILL LIKELY INCLUDE GUSTY
WINDS...FREQUENT LIGHTNING AND THE POSSIBILITY OF HAIL.

&&

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

$$

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