Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS64 KHGX 281729
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1229 PM CDT THU APR 28 2016

.AVIATION...
MVFR CLOUD DECK NEAR/ALONG THE COAST IS GRADUALLY WORKING ITS WAY INLAND.
COULD SEE SOME PERIOD OF VFR CONDITIONS THIS AFTERNOON...BUT EXPECT
MVFR/IFR CEILINGS TO BE REACHED THIS EVENING AND/OR OVERNIGHT. COULD
HAVE SOME SHRA/TSRA TOO (MAINLY NORTHERN TAFS)...BUT ANTICIPATE THE
BULK OF (AND LOTS OF) SHRA/TSRA TO BEGIN FRIDAY NIGHT.  42
&&

.PREV DISCUSSION... /ISSUED 1130 AM CDT THU APR 28 2016/

DISCUSSION...
WARM START TO THE DAY WITH A WARM FRONT JUST OFF THE COAST OF
GALVESTON AND COMING ONSHORE NEAR FREEPORT AND PALACIOS. 75-78
DEWPOINTS ABOUND SOUTH OF THE WARM FRONT ALONG WITH HAZY/FOGGY
CONDITIONS. THE WARM FRONT SHOULD LIFT NORTHWARD TODAY...SLOWLY
THIS MORNING THEN PICKING UP SPEED LATE THIS AFTERNOON SURGING
THROUGH COLLEGE STATION AND HUNTSVILLE BY LATE AFTERNOON. ALTHOUGH
SOME OF THE HIGH RES MODELS SHOW A FEW SHOWERS DEVELOPING THINK
THE COVERAGE IS PROBABLY GENEROUS AND HAVE PARED BACK POPS IN THE
SOUTH AND DELAYED THE ONSET OF RAIN CHANCES INTO MID AFTERNOON.
CAP SHOULD HOLD THIS AFTERNOON. TONIGHT STILL APPEARS THAT CHANCE
POPS ARE IN ORDER ACROSS THE FAR NORTH.

CONCERN GROWING FOR ANOTHER HEAVY RAIN EVENT ACROSS SETX FRIDAY
NIGHT THROUGH EARLY SUNDAY. TREMENDOUS MOISTURE ADVECTION WITH
STEEP LAPSE RATES ALOFT POINTING TO HIGHLY EFFICIENT STORMS AND
POTENTIAL FOR TRAINING AS LF QUAD OF JET COMES INTO PLAY FIRST AND
THEN BRANCHING OFF OF POLAR JET TO THE NORTH HELPS WITH SPEED
DIVERGENCE AND DIFFLUENCE ACROSS THE REGION SATURDAY MORNING.
GIVEN THE ANTECEDENT SOIL MOISTURE THE FLASH FLOOD THREAT SPIKES
FRIDAY NIGHT AND SATURDAY MORNING.

45

PREV DISCUSSION... /ISSUED 414 AM CDT THU APR 28 2016/

SHORT TERM /TODAY THROUGH FRIDAY/...
MUCH QUIETER CONDITIONS UNDERWAY ACROSS SOUTHEAST TEXAS EARLY
THIS MORNING THAN 24 HOURS AGO AS AN UPPER LOW OVER THE NORTHERN
PLAINS CONTINUES TO LIFT TOWARDS THE GREAT LAKES... WITH LITTLE
MORE GOING ON THAN LOW STRATUS AND PATCHY FOG CONTINUING TO SPREAD
ACROSS THE REGION. MOST VISIBILITIES ARE AT OR ABOVE 1 MILE AS OF
4 AM... WITH ONLY A FEW ISOLATED LOCATIONS REPORTING DENSE FOG.
WILL KEEP AN EYE ON VISIBILITIES FOR ANY POSSIBLE DENSE FOG
ADVISORY ISSUANCE IF COVERAGE BECOMES MORE WIDESPREAD /SREF
GUIDANCE INDICATING THIS IS A POSSIBILITY WEST OF INTERSTATE 45
CLOSER TO SUNRISE/ BUT WILL HOLD OFF ON ANY HEADLINES NOW DUE TO
LOW CONFIDENCE. DAYTIME HEATING WILL ALLOW THE FOG AND LOW CLOUDS
TO MIX OUT MID TO LATE THIS MORNING.

AS A WARM FRONT LIFTS INLAND LATER THIS AFTERNOON... SPOTTY WARM
AIR ADVECTION SHOWERS WILL BE POSSIBLE ACROSS THE REGION. FORECAST
SOUNDINGS MAINTAIN A WEAK CAPPING INVERSION THROUGH THE AFTERNOON
HOURS AND THIS SHOULD HELP MAINTAIN ISOLATED COVERAGE... BUT A
STRONGER UPDRAFT OR TWO MAY BE ABLE TO BREAK THE CAP AND TAKE
ADVANTAGE OF STEEP MID LEVEL LAPSE RATES /BETWEEN 7-8 C PER KM/
FOR ISOLATED THUNDERSTORM DEVELOPMENT. OTHERWISE... EXPECT HIGH
TEMPERATURES TODAY TO RISE INTO THE MID TO UPPER 80S. WILL NEED TO
MONITOR SKY TRENDS AS THIS WILL HAVE A MAJOR IMPACT ON WHAT HIGH
TEMPERATURES ARE REALIZED TODAY.

FOR TONIGHT... AN UPPER TROUGH LOCATED NEAR SOUTHERN NEVADA ON
WATER VAPOR IMAGERY EARLY THIS MORNING WILL SHIFT FARTHER EAST AND
REACH THE FOUR CORNERS REGION. AS THIS HAPPENS... SOUTHWEST FLOW
ALOFT WILL BECOME ESTABLISHED ACROSS SOUTHEAST TEXAS AND LEE
CYCLOGENESIS WILL BEGIN ACROSS THE HIGH PLAINS. INCREASING
SOUTHERLY TO SOUTHEASTERLY FLOW WILL ALLOW PRECIPITABLE WATER
VALUES TO CLIMB TO NEAR 1.5 INCHES TONIGHT... WITH DISTURBANCES
MOVING ACROSS TEXAS IN THE FLOW ALOFT TRIGGERING PERIODS OF
SHOWERS AND THUNDERSTORMS. LATEST 00Z GUIDANCE PROVIDES A MORE
NORTHERLY TRAJECTORY TO THESE DISTURBANCES THAN PREVIOUSLY
ADVERTISED /POSSIBLY OWING TO GUIDANCE BETTER RESOLVING MID-LEVEL
RIDGING NEAR TO JUST EAST OF THE REGION TODAY/ AND THIS WOULD KEEP
MOST OF THIS ACTIVITY NORTH OF THE REGION TONIGHT. HOWEVER...
STILL HIGHLIGHTING LOW RAIN CHANCES /20 TO 30 POPS/ NORTH OF
HIGHWAY 59 DUE TO SOME UNCERTAINTY WITH THE ACTUAL TRAJECTORY OF
THESE DISTURBANCES. OTHERWISE... INCREASING LOW LEVEL MOISTURE AND
RETURNING CLOUD COVER TONIGHT WILL KEEP OVERNIGHT LOWS FAIRLY WARM
IN THE LOW TO MID 70S.

ON FRIDAY... THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG THE
DRYLINE ACROSS WEST CENTRAL TEXAS AS THE UPPER LOW NEAR THE FOUR
CORNERS LIFTS INTO THE CENTRAL PLAINS. WHILE THESE THUNDERSTORMS
WILL DEVELOP WELL WEST OF THE REGION... THESE THUNDERSTORMS MAY
GROW UPSCALE INTO ANOTHER THUNDERSTORM COMPLEX THAT WILL MOVE
EAST/SOUTHEAST TOWARDS THE REGION ALONG A FRONTAL BOUNDARY DURING
THE AFTERNOON AND EVENING HOURS. ADDITIONALLY... SUBTLE
DISTURBANCES MOVING ACROSS THE REGION IN THE FLOW ALOFT MAY BE
ABLE TO TRIGGER SCATTERED THUNDERSTORMS DURING THE DAY AHEAD OF
THE MAIN THUNDERSTORM COMPLEX... WHICH MAY POSE A DAMAGING WIND
AND ISOLATED TORNADO THREAT AS IT MOVES ACROSS THE REGION HEADING
INTO FRIDAY NIGHT.

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...

THE POSSIBILITY FOR SEVERAL ROUNDS OF RAINFALL /SOME HEAVY/ WILL
EXIST ACROSS SOUTHEAST TEXAS IN THE LONG TERM PORTION OF THE
FORECAST.

FOR FRIDAY NIGHT INTO SATURDAY NIGHT... A THUNDERSTORM COMPLEX
AND ASSOCIATED FRONTAL BOUNDARY IS EXPECTED TO SAG ACROSS THE
REGION FROM THE NORTH FRIDAY NIGHT INTO EARLY SATURDAY MORNING
AHEAD OF AN ATTENDANT FRONTAL BOUNDARY. THIS COMPLEX MAY BE
CAPABLE OF DAMAGING WINDS AND AN ISOLATED TORNADO OR TWO AS IT
MOVES INTO THE REGION. ADDITIONALLY... CORFIDI VECTORS SHOW THE
MOTION OF THE THUNDERSTORM COMPLEX ORIENTED ROUGHLY PARALLEL TO
THE FRONTAL BOUNDARY... RAISING CONCERNS FOR TRAINING
THUNDERSTORMS AS THE BOUNDARY SLOWLY PUSHES ACROSS THE REGION ON
SATURDAY. THIS... COUPLED WITH A DIVERGENT WIND FIELD ALOFT AND
PRECIPITABLE WATER VALUES ACROSS THE REGION FORECAST TO RISE TO
AROUND 1.8 TO 2.0 INCHES /ABOVE THE 90TH CLIMATOLOGICAL PERCENTILE
FOR THIS TIME OF YEAR/... ALSO FOCUSES ATTENTION ON LATE FRIDAY
NIGHT INTO SATURDAY NIGHT FOR THE POSSIBILITY OF HEAVY RAINFALL.
ADDING FURTHER SUPPORT TO OUR ANOMALOUSLY MOIST AIRMASS... ALMOST
HALF /47 PERCENT/ OF 12Z NAEFS ENSEMBLE MEMBERS FORECAST
PRECIPITABLE WATER VALUES OUTSIDE OF CLIMATOLOGY DURING THIS TIME.

UNFORTUNATELY... GUIDANCE CONTINUES TO HAVE POOR AGREEMENT ON
PLACEMENT OF GREATEST FORECAST RAINFALL WITH CONVECTIVELY INDUCED
QPF BULLSEYES POPPING UP FROM MODEL TO MODEL AND RUN TO RUN. WILL
NEED TO PAY PARTICULAR ATTENTION TO WHEREVER THE FRONTAL BOUNDARY
SETS UP /OR STALLS/ FOR THE GREATEST RAINFALL THREAT. OF NOTE...
UNLIKE THE PAST FEW THUNDERSTORM COMPLEXES THAT MOVED ACROSS THE
REGION... MEAN FLOW IS ORIENTED PARALLEL TO THE FRONTAL BOUNDARY
/WHICH WILL HELP LIMIT THE UPPER SUPPORT FOR THE FRONTAL BOUNDARY
TO PUSH SOUTH QUICKLY/.

RAIN CHANCES BEGIN TO TAPER OFF SUNDAY AS THE UPPER LOW OVER THE
CENTRAL PLAINS LIFTS FARTHER NORTH AND WEAKENS... BUT PERIODS OF
SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE THROUGH TUESDAY AS
UPPER DISTURBANCES TRANSLATE ACROSS THE SOUTHERN PLAINS. DRY
WEATHER IS EXPECTED WEDNESDAY THROUGH THE END OF THE WEEK AS UPPER
RIDGING BUILDS ACROSS THE REGION.

HUFFMAN

MARINE...
AREAS OF 2-6NM FOG NOTED IN THE GULF WATERS. THIS WILL PROBABLY
CONTINUE FOR A FEW DAYS BUT AM NOT ANTICIPATING MUCH IN THE WAY OF
DENSE FOG. OTHERWISE...FAIRLY LIGHT ESE WINDS TODAY WILL VEER TO
THE SE AND INCREASE LATER TONIGHT, FRI AND INTO SATURDAY MORNING.
WILL LIKELY NEED CAUTION/ADVISORY FLAGS AS EARLY AS TONIGHT. FETCH
OF MODERATE TO STRONG ONSHORE FLOW WILL LENGTHEN ALLOWING FOR SOME
6- 8FT SEAS TO MAKE THEIR WAY TOWARD THE COAST WHICH WILL RESULT
IN BUILDING SURF AND THREATS OF RIP CURRENTS. WILL ALSO NEED TO
KEEP AN EYE ON WATER LEVELS. THINK THEY`LL PROBABLY PEAK BELOW
IMPACT LEVELS TODAY (THOUGH MAY GET CLOSE TO HWY 87/124)...BUT
SHOULD BE A BIT HIGHER FRI-SAT AROUND TIMES OF HIGH TIDE. FAIRLY
UNSETTLED WX WILL PERSIST THROUGHOUT THE WEEKEND INTO EARLY NEXT
WEEK. THOUGH DIFFICULT TO TIME PRECIPITATION/LOCATION THIS FAR IN
ADVANCE...MARINERS SHOULD PLAN FOR GOOD POSSIBILITIES OF STORMS
EACH DAY. 47

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      86  74  86  68  81 /  20  30  40  70  70
HOUSTON (IAH)              86  75  85  70  81 /  10  20  40  60  70
GALVESTON (GLS)            81  75  80  74  79 /  10  10  30  40  60

&&

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

$$

DISCUSSION...45
AVIATION/MARINE...42



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.