Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 312226
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
426 PM CST SAT JAN 31 2015

.DISCUSSION...
LIGHT SHOWERS ASSOCIATED WITH AN UPPER LEVEL DISTURBANCE OVER
SOUTHERN ARIZONA HAVE BEGUN TO PUSH INTO THE WESTERN PORTIONS OF
SOUTHEAST TEXAS. A FEW IMPULSES OUT AHEAD OF THE MAIN SYSTEM LOOK
TO BE THE DRIVER BEHIND THE LIGHT SHOWERS. THE LIMITING FACTOR IN
PRECIPITATION LOOKS TO BE THE CONTINUED UPPER RIDGING...WHICH
ALTHOUGH HAS SHIFTED OFF TO THE EAST...IS STILL AN INHIBITING
FACTOR. IR SATELLITE IMAGERY SHOWS MOST OF THE CONVECTION IS
RIDING AROUND THE RIDGE INTO THE CENTRAL PLAINS. SHORT RANGE
MODELS ARE NOT VERY AGGRESSIVE WITH BRINGING THE RAIN INTO
SOUTHEAST TEXAS...WITH MOST OF THE RAIN OUT OF THE AREA BY 15Z
SUNDAY. 250 MB GFS AND ECMWF DEPICT A WARM POCKET FARTHER TO THE
SOUTH AND WEST OF THE AREA. BOTH MODELS SHOW A JET STREAK PRESENT
OVER SOUTHEAST TEXAS SATURDAY NIGHT INTO SUNDAY MORNING...PLACING
SOUTHEAST TEXAS IN THE FAVORED QUADRANT FOR CONVERGENCE AT THE
SURFACE. 500 MB GFS AND ECMWF POSITIVE VORTICITY ADVECTION IS NOT
PARTICULARLY STRONG FROM SATURDAY NIGHT THROUGH SUNDAY. 700MB GFS
OMEGA VALUES ARE NOT VERY HIGH...WITH VALUES NEVER EXCEEDING 8
ACROSS SOUTHEAST TEXAS. BOTH THE GFS AND ECMWF 700 MB DEWPOINT
DEPRESSIONS ARE 5 DEGREES C OR BELOW FROM 00Z SUNDAY THROUGH 18Z
SUNDAY. 850MB GFS AND ECMWF WINDS SHOW 30KT WAA FROM 00Z SUNDAY
THROUGH 12Z SUNDAY LIKELY PROVIDING THE LIFT NECESSARY TO CAUSE
SOME SHOWERS ACROSS SOUTHEAST TEXAS TONIGHT THROUGH TOMORROW
MORNING. THE GFS AND ECMWF ARE BRINGING THE COLD FRONT THROUGH
SOUTHEAST TEXAS BETWEEN 18Z SUNDAY TO 6Z MONDAY...HAVING THE FRONT
OFF THE COAST BY 6Z MONDAY. THE NAM IS ABOUT 3 HOURS BEHIND THE
THE LONGER RANGE MODELS. THERE MAY BE SOME LIGHT SHOWERS BEHIND
THE COLD FRONT THAT WILL LIKELY COME TO AN END BY THE TIME THE
850MB FRONT MOVES THROUGH THE AREA...BY 15Z MONDAY.

MONDAY AND TUESDAY WILL BE COLD AND CLEAR WITH AREAS NORTH OF
INTERSTATE 10 LIKELY EXPERIENCING MIDDLE TO UPPER 30S FOR LOWS
MONDAY AND TUESDAY MORNING. GFS AND ECMWF SHOW A 1000-500MB
THICKNESS VALUE OF 548 DM MAKING IT INTO THE CENTRAL PORTIONS OF
SOUTHEAST TEXAS... BUT REMAINING NORTH OF METRO HOUSTON.
1000-500MB WINDS WILL BE RIGHT AROUND 30-35 KTS ADVECTING COLDER
AIR INTO THE REGION. THE GFS IS SHOWING STRONG CAA MONDAY MORNING
WITH 850 MB WINDS OF 50 KTS...WITH THE ECMWF A BIT SLOWER WITH THE
WINDS.

ON WEDNESDAY...A COASTAL TROUGH WILL MOVE NORTH ALONG THE TEXAS
COAST BRINGING ANOTHER CHANCE FOR RAINFALL FOR SOUTHEAST TEXAS.
LATER IN THE WEEK THROUGH THE WEEKEND HIGH PRESSURE WILL BUILD
INTO THE AREA.
13
&&

.MARINE...

...GALE WATCH IN EFFECT FOR THE OFFSHORE WATERS LATE SUNDAY NIGHT
INTO MONDAY MORNING...

EASTERLY WINDS WILL CONTINUE TO RESULT IN TIDES ABOUT A HALF FOOT TO
ONE FOOT ABOVE NORMAL THIS AFTERNOON AND EVENING... BEFORE THE
REGION LOSES THE INFLUENCE OF SURFACE HIGH PRESSURE AND WINDS BECOME
MORE SOUTHERLY AND DECREASE. LIGHT SCATTERED SHOWERS WILL BE
POSSIBLE DURING THE OVERNIGHT HOURS AS SEVERAL DISTURBANCES CROSS
THE AREA...WITH AN ADDITIONAL ROUND OF SHOWERS /WITH AN EMBEDDED
THUNDERSTORM OR TWO/ POSSIBLE ALONG A STRONG COLD FRONT. RAIN
COVERAGE WILL BE SPOTTY AT BEST... BUT LIGHTNING WILL STILL POSE AN
ISOLATED THREAT.

THE COLD FRONT IS PRESENTLY PUSHING THROUGH THE NORTHERN GREAT
PLAINS AND IS EXPECTED TO REACH THE UPPER TEXAS COAST SOMETIME
AROUND SUNSET ON SUNDAY. WINDS WILL BEGIN SHIFTING FROM THE SOUTH TO
THE SOUTHWEST SUNDAY AFTERNOON AHEAD OF THE FRONT AS A PREFRONTAL
TROUGH REACHES THE COASTAL WATERS...WITH WINDS INCREASING
DRAMATICALLY OUT OF THE NORTH BEHIND THE FRONT SUNDAY EVENING. GIVEN
THE STRENGTH OF THE THERMAL GRADIENT ASSOCIATED WITH THIS FRONT...
WIND GUSTS NEAR GALE FORCE WILL BE POSSIBLE LATE SUNDAY NIGHT INTO
MONDAY MORNING AND A GALE WATCH IS IN EFFECT FOR THIS TIME.
ADDITIONALLY... INCREASED WINDS AND BUILDING SEAS WILL LIKELY PROMPT
THE ISSUANCE OF SMALL CRAFT ADVISORIES FOR THE BAYS AND COASTAL
WATERS. LATE SUNDAY INTO MONDAY MORNING WILL SEE CHALLENGING
CONDITIONS FOR MARINERS. SLIGHTLY BELOW NORMAL TO BELOW NORMAL TIDES
WILL ALSO BE POSSIBLE BEHIND THIS FRONT.

A BRIEF RESPITE FROM UNSETTLED CONDITIONS LATE MONDAY INTO EARLY
TUESDAY WILL QUICKLY BE REPLACED BY ANOTHER ROUND OF RAIN AS AN
APPROACHING DISTURBANCE NEAR BAJA CALIFORNIA INDUCES A COASTAL
TROUGH ALONG THE EASTERN MEXICAN COAST ON TUESDAY. MODEL GUIDANCE
CONTINUES TO COME INTO BETTER AGREEMENT WITH THE PLACEMENT OF BOTH
THE UPPER AND SURFACE DISTURBANCES AND THE COASTAL LOW LOOKS TO
TRACK ALONG THE TEXAS COAST LATE TUESDAY INTO WEDNESDAY.

HUFFMAN


&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      58  68  35  50  36 /  60  60  10   0   0
HOUSTON (IAH)              58  72  38  52  37 /  50  70  20   0   0
GALVESTON (GLS)            58  67  41  51  43 /  40  50  30   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...GALE WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY MORNING 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...13
MARINE/AVIATION...14



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