Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 190639 AAB
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
139 AM CDT SUN OCT 19 2014

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

&&

.AVIATION...BROWNSVILLE RADAR INDICATES A FEW SHOWERS SOUTH OF THE
RIO GRANDE RIVER EARLY THIS MORNING. ISOLATED SHOWERS AND
THUNDERSTORMS WILL DEVELOP AND MOVE ACROSS THE DEEP SOUTH TEXAS
LATER THIS MORNING INTO THE AFTERNOON. WILL MENTION VCSH NOW
THROUGH 18Z FOR BRO/HRL AND THROUGH 00Z AT MFE. ALSO HAVE ADDED PROB30
FOR MFE FOR POSSIBLE MVFR CONDITIONS FOR HEAVIER CONVECTION BETWEEN
18 TO 22Z. CEILINGS RANGE FROM 35000FT AT MFE TO NEAR 15000FT AT
HRL. EXPECT MVFR CONDITIONS TO DEVELOP BEFORE SUNRISE WITH PATCHY FOG
DEVELOPING ACROSS PORTIONS OF THE RIO GRANDE VALLEY...ESPECIALLY
AT MFE. OTHERWISE...VFR CONDITIONS SHOULD PREVAIL THROUGH THE PERIOD.

&&

.PREV DISCUSSION... /ISSUED 649 PM CDT SAT OCT 18 2014/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...SATELLITE AND RADAR IMAGES AS WELL AS SURFACE
OBSERVATIONS INDICATE ISOLATED TO SCATTERED CONVECTION ACROSS THE
EXTREME WESTERN AND SOUTHERN PORTIONS OF THE CWA EARLY THIS
EVENING. CEILINGS WERE NEAR 4600FT AT KBKS TO NEAR 7500FT AT KHRL.
EXPECT MVFR CONDITIONS TO DEVELOP TONIGHT WITH PATCHY FOG
DEVELOPING ACROSS PORTIONS OF THE RIO GRANDE VALLEY. OTHERWISE...VFR
CONDITIONS WILL PREVAIL THIS EVENING THROUGH SUN MORNING.

PREV DISCUSSION... /ISSUED 358 PM CDT SAT OCT 18 2014/
SHORT TERM /NOW THROUGH SUNDAY NIGHT/...CONVECTIVE LINE CONTINUES
TO CHURN RIGHT ALONG THE COAST...WITH INACTIVE OUTFLOWS DRIFTING
FURTHER INLAND. PW IMAGERY SHOWS DEEPEST MOISTURE JUST STARTING TO
MOVE INTO THE WESTERN VALLEY...SO SOME SHOWER ACTIVITY MAY FINALLY
DEVELOP INLAND BEFORE SUNSET. MODELS GRADUALLY SHIFT THE MOISTURE
FURTHER INLAND...AND WITH A WEAK MIDLEVEL VORT TRYING TO MOVE
THROUGH THIS EVENING...SOME SHOWER ACTIVITY EXPECTED TO DRIFT
ACROSS THE REGION OVERNIGHT AND AGAIN TOMORROW. SOME LIGHT FOG IS
POSSIBLE AREAWIDE OVERNIGHT...BUT LARGER DEPTH OF MOISTURE WILL
KEEP FOG FROM GETTING TOO THICK. MODELS CONTINUE TO SHOW BETTER
RAIN CHANCES ACROSS THE WESTERN AREAS INTO THE BRUSH COUNTRY ON
SUNDAY...SO HAVE TAILORED POP CHANCES TO ACCOUNT FOR THIS.
MOISTURE REMAINS INTO SUNDAY NIGHT WITH CONTINUES SMALL CHANCES
FOR POPS. /64/

LONG TERM /MONDAY THROUGH SATURDAY/...
PERSISTENT EASTERLY FLOW...THANKS IN PART TO A SURFACE RIDGE
CENTERED OVER THE MID-ATLANTIC...WILL ALLOW LOW-LEVEL MOISTURE TO
CONTINUE FLOWING INTO THE REGION.  BY MONDAY...PRECIPITABLE WATER
VALUES ARE EXPECTED TO APPROACH 2 INCHES IN MANY PARTS OF OUR
AREA...WHICH IS BETWEEN 1 AND 2 STANDARD DEVIATIONS ABOVE NORMAL FOR
OCTOBER.  THIS...COMBINED WITH AN INVERTED SURFACE TROUGH EMANATING
FROM A SURFACE LOW IN THE BAY OF CAMPECHE...WILL RESULT IN A
CONTINUED POSSIBILITY OF SEEING SHOWERS AND STORMS EARLY NEXT WEEK.
CONVECTIVE COVERAGE SHOULD BE GREATEST OVER SOUTHERN AND WESTERN
PORTIONS OF THE FORECAST AREA...COINCIDENT WITH THE HIGHEST
PRECIPITABLE WATER VALUES.

AN UPPER LEVEL TROUGH IS EXPECTED TO MOVE ACROSS THE OHIO VALLEY
TUESDAY.  THIS FEATURE SHOULD PUSH A COLD FRONT FROM THE TENNESSEE
AND LOWER MISSISSIPPI VALLEYS TO THE NORTHERN GULF OF MEXICO BY
WEDNESDAY.  MOST OF THE MOMENTUM FOR THIS FRONT SHOULD REMAIN WELL
TO OUR NORTH AND EAST...WHICH RAISES THE QUESTION ABOUT A (WEAK)
FRONTAL PASSAGE IN OUR AREA AROUND MID-WEEK.  LATEST MEDIUM RANGE
MODELS SUGGEST THE POSSIBILITY OF A SURFACE TROUGH PASSAGE
WEDNESDAY-ISH.  WINDS WILL LIKELY BACK TO A MORE NORTHEASTERLY
DIRECTION AND INCREASE IN SPEED AFTER THE PASSAGE OF ANY TROUGH.

REGARDLESS OF WHETHER A FRONT MOVES THROUGH THE FORECAST AREA...A
SURFACE RIDGE...BUILDING SOUTHWARD ACROSS THE UPPER MIDWEST AS THE
WEAK GULF LOW MOVES NORTHEAST...WILL USHER DRIER AIR INTO THE REGION
LATE WEDNESDAY AFTERNOON/EVENING.  THIS WILL EFFECTIVELY BRING AN
END TO THE RAIN.

FORECAST CONFIDENCE WANES A BIT HEADING TOWARD THE END OF THE WEEK.
IT LOOKS LIKE AN UPPER LEVEL LOW WILL MOVE FROM THE PLAINS INTO
TEXAS TOWARD THE END OF THE WEEK.  DISCREPANCIES IN THE LOCATION AND
TIMING OF THIS FEATURE ARE RAMPANT WITHIN THE MEDIUM RANGE MODEL
WORLD THIS AFTERNOON.  THE MORE LIKELY SOLUTION BRINGS THE LOW
TOWARD THE SOUTHEAST TEXAS/SOUTHWEST LOUISIANA COAST BY SATURDAY.
BASED ON THIS TIMING...I DON`T SEE A RETURN OF SIGNIFICANT AMOUNTS
OF LOW-LEVEL MOISTURE IN ADVANCE OF THIS SYSTEM.  AS SUCH...I HAVE
KEPT ANY PRECIPITATION PROBABILITIES BELOW 15 PERCENT (DESPITE WHAT
GUIDANCE FROM THE LATEST MODEL BLENDS SUGGEST).

THANKS TO WFO CORPUS CHRISTI FOR COLLABORATION THIS AFTERNOON.  /53/

MARINE...

NOW THROUGH SUNDAY NIGHT...
MODEST SOUTHEAST WINDS CONTINUE TO PRODUCE SEAS IN THE 3 TO 4 FOOT
RANGE. WITH LOW PRESSURE DRIFTING AROUND THE BAY OF CAMPECHE AND
HIGH PRESSURE PASSING THROUGH THE LOWER MISSISSIPPI
VALLEY...GENERALLY ONSHORE FLOW WILL CONTINUE THROUGH THE NEXT 36
HOURS. WINDS WILL REMAIN AROUND 15 KNOTS THROUGH THE
PERIOD...KEEPING THE CURRENT SEA STATE THROUGH SUNDAY NIGHT. NO
FLAGS EXPECTED FOR THE REST OF THE WEEKEND. /64/

MONDAY THROUGH THURSDAY...
MODERATE WINDS AND SEAS ARE EXPECTED AS WE HEAD INTO THE LONG TERM
PORTION OF THE FORECAST.  INCREASING WIND SPEEDS AND BUILDING SEAS
WILL LIKELY BE SEEN OVER THE MARINE AREA BY TUESDAY NIGHT...THANKS
TO A TIGHTENING PRESSURE GRADIENT.  THIS MAY RESULT IN EITHER SMALL
CRAFT NEEDING TO EXERCISE CAUTION OR THE ISSUANCE OF SMALL CRAFT
ADVISORIES BY MID-WEEK.  SHOWERS AND STORMS WILL REMAIN POSSIBLE
THROUGH EARLY WEEK...UNTIL DRIER AIR MOVES INTO THE MARINE AREA
WEDNESDAY NIGHT.  /53/

&&

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

$$

THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
HTTP://WEATHER.GOV/RGV

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