Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 202340
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
540 PM CST THU NOV 20 2014

.DISCUSSION...
SEE THE 00Z AVIATION DISCUSSION BELOW.

40

&&

.AVIATION...
AN ACTIVE SUBTROPICAL JET ALOFT WAS HELPING TO PROVIDE FOR A MID
LAYER CLOUD DECK AND SCATTERED LIGHT /FOR THE MOST PART/ RAIN
SHOWERS. EXPECT THAT THE SHOWERS WILL DIMINISH THROUGH THE EVENING
AS THE MAIN JET DYNAMICS MOVE OUT TO THE NORTHEAST. THE NAM MOS
GUIDANCE AND THE NAM AND GFS MODEL SOUNDINGS ALL POINT TOWARD VFR
CONDITIONS FOR MOST OF THE TERMINAL SITES. BETTER CHANCES FOR MVFR
WILL EXIST AFTER 06Z AT KCLL AND KUTS...AND TO A LESSER EXTEND
KCXO. THE MAIN MOISTURE CORRIDOR WILL BE OVER THESE LOCATIONS. FOR
THE REMAINING SITES VFR SHOULD PERSIST THROUGH FRIDAY AFTERNOON.
ANOTHER FAVORABLE POSITION OF THE UPPER LEVEL JET WILL BEGIN
AFFECTING SE TX FRIDAY AFTERNOON AND BRING BETTER CHANCES FOR
SHOWERS DURING THE AFTERNOON AND LOWER CEILINGS DURING THE
EVENING.

40

&&

.PREV DISCUSSION... /ISSUED 329 PM CST THU NOV 20 2014/

DISCUSSION...
ISENTROPIC UPGLIDE HAS CONTINUED THIS AFTERNOON WITH BEST MOISTURE
AROUND MATAGORDA BAY. RADAR SHOWS MOST RETURNS BEING VERY LIGHT
WITH SLIGHTLY BETTER COVERAGE TO THE WEST. THINKING IS THAT LIGHT
SHOWERS WILL INCREASE IN COVERAGE OVERNIGHT AND THEN SLOWLY
CONCENTRATE MORE TO THE NORTH BY TOMORROW AFTERNOON. HIGH RES
MODELS HAVE STRUGGLED THIS AFTERNOON OVER DOING THE COVERAGE
ACROSS OUR AREA THOUGH.

ON SATURDAY A POTENT UPPER LEVEL LOW WILL PUSH EAST INTO THE AREA
AND BE THE FOCUS FOR WIDESPREAD SHOWERS AND THUNDERSTORMS. THE
UPPER LEVEL LOW STILL LOOKS TO TAKE ON A NEGATIVE TILT AS IT
CROSSES THE AREA WITH AMPLE SHEAR IN THE SOUNDING PROFILE. PWAT
VALUES ALSO SURGE TOWARDS 1.70" (~ + 2SD FOR THIS TIME OF YEAR).
DUE TO THE MENTIONED ABOVE SPC HAS PUT THE AREA IN A ENHANCED RISK
FOR DAY 3. THE MAIN THREATS WITH THESE STORMS WILL BE DAMAGING
WINDS AND ISOLATED TORNADOES. THE EVENT LOOKS TO START LATE
SATURDAY MORNING/ EARLY SATURDAY AFTERNOON AND CONTINUE THROUGH
THE EVENING. MODELS HAVE HINTED AT A SLIGHT SLOWING OF THE
PROGRESSION OF THE UPPER LEVEL LOW WHICH WOULD ALLOW POPS TO
CONTINUE INTO SUNDAY MORNING BEFORE SUNRISE.

AS THE UPPER LEVEL LOW PASSES OVER SOUTHEAST TEXAS MUCH DRIER AIR
WILL FILTER INTO THE AREA SUNDAY BRINGING A QUICK END TO THE RAIN
AND CLOUDS. THE ACTUAL COLD FRONT WILL NOT PASS THROUGH THE AREA
UNTIL MONDAY MORNING THOUGH. THIS MEANS THAT SUNDAY WILL LIKELY BE
WARM AS 850 WINDS TURN WESTERLY WITH 850 TEMPS WARMING TO NEAR
15C. STARTING MONDAY AND CONTINUING THROUGH WEDNESDAY TEMPERATURES
WILL REMAIN BELOW NORMAL THANKS TO A REINFORCING FRONT TUESDAY. 23

MARINE...
ONSHORE WINDS WILL CONTINUE TO STRENGTHEN ACROSS THE
COASTAL WATERS THIS EVENING. WILL UPGRADE TO AN ADVISORY FOR THE
OFFSHORE WATERS OVERNIGHT AND ADD CAUTION FOR THE NEARSHORE. WITH
THE INCREASED ONSHORE FLOW SEAS WILL BUILD OVERNIGHT. THIS STRONGER
ONSHORE FLOW WILL PERSIST INTO SATURDAY AHEAD OF AN APPROACHING
UPPER LEVEL STORM SYSTEM. THIS SYSTEM WILL BRING SHOWERS AND
THUNDERSTORMS TO THE COASTAL WATERS ON SATURDAY WITH STRONG TO
SEVERE THUNDERSTORMS POSSIBLE SATURDAY AFTERNOON AND NIGHT. WINDS
WILL BECOME SOUTHWESTERLY IN THE WAKE OF THIS SYSTEM ON SUNDAY WITH
ANOTHER FRONT EXPECTED TO MOVE OFFSHORE EARLY MONDAY. 38

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      61  73  62  71  57 /  50  60  30  80  60
HOUSTON (IAH)              61  74  61  74  61 /  50  40  20  80  80
GALVESTON (GLS)            65  72  65  72  63 /  40  40  20  80  80

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH LATE TONIGHT FOR THE
     FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP
     CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT
     20 NM.

     SMALL CRAFT ADVISORY UNTIL 6 AM CST FRIDAY FOR THE FOLLOWING
     ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
     20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO
     60 NM.

     SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 6 PM CST THIS EVENING
     FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE
     MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH
     ISLAND TO FREEPORT 20 TO 60 NM.

&&

$$

DISCUSSION...43
AVIATION/MARINE...40



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