Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 161513
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1013 AM CDT THU APR 16 2015

.UPDATE...
A SURFACE WARM FRONT NOW ANALYZED JUST INLAND...DRAPED NEAR PARALLEL
TO THE COAST FROM A PORT ARTHUR...ANGLETON THROUGH VICTORIA LINE.
LOCAL AREA 12Z SOUNDINGS SHOWING MILD CAPPING (CRP) TO DECENT LAPSE
RATES (LCH) AND HIGH MOISTURE OF AROUND 1.70 TO 1.75 INCH PWS (JUST
UNDER 2 STD DEVS FOR THIS TIME OF YEAR). A COUPLE OF THUNDERSTORMS
HAVE ALREADY FLARED UP OVER NE`ERN HARRIS COUNTY AND JUST OFFSHORE
OF GALVESTON WITHIN THE LAST HOUR SO WHAT LITTLE EARLY DAY CAPPING
WE HAD WILL BE A MUTE POINT VERY SOON. A SHORTWAVE DISTURBANCE
MOVING OUT OF MEXICO BETWEEN THE BIG BEND AND LAREDO IS FIRING UP
SCATTERED CONVECTION OVER SAN ANTONIO`S WESTERN CWA. THIS TRIGGER
SHOULD BE ENOUGH TO COMMENCE WESTERN AND NORTHERN FORECAST AREA
MORE AREAWIDE RAIN AND THUNDERSTORMS LATTER TODAY. THE LOCATION OF
THE HEAVIEST RAINFALL MAY FOCUS ALONG THE AFOREMENTIONED WARM FRONTAL
BOUNDARY OR SUBSEQUENT (DOWNSTREAM) PRIOR CONVECTION OUTFLOW BOUNDARIES.
OTHER ARGUMENTS TO AN ACTIVE COUPLE OF DAYS WILL A MOISTENING COLUMN
AND FAVORABLE UPPER LEVEL DIVERGENCE. 85H TDD VALUES OF LESS THAN
3 DEGREES ARE ADVECTING UP WITHIN THE MID-LEVEL SOUTHERN STEERING
FLOW AS THE NORTHERN-CREEPING SOUTHERN JET BRANCH PLACES A MORE
FAVORABLE LEFT FRONT QUADRANT OVER EASTERN TEXAS. ALL OF THESE
DETAILS ASIDE...SIMPLY THE ONGOING SYNOPTIC SET-UP SHOULD SUFFICE
FOR A FEW ACTIVE DAYS. THAT BEING THE SLOW-MOVING FOUR CORNERS
UPPER LOW PLACING TEXAS WITHIN A STOUT SOUTHWESTERLY AND DIFFULENT
FLOW PATTERN WELL INTO THE WEEKEND. 31

&&

.PREV DISCUSSION... /ISSUED 650 AM CDT THU APR 16 2015/

AVIATION...
A QUICK UPDATE TO PREVIOUS...BAND OF SHOWERS FROM NEAR 11R-UTS-
SOUTH OF LFK LIFTING SLOWLY NORTH APPEARS TO BE ASSOCIATED WITH
NORTHERN LIMIT OF DEEPER MOISTURE AND TROPICAL PACIFIC TAP AND S/W
MOVING INTO NCTX. ANOTHER S/W LOOKS TO BE CROSSING THE RIO GRANDE
IN THE SUBTROPICAL FLOW AND EXPECT TO SEE STORMS FLARE UP OVER THE
AREA LATE THIS MORNING AND EXPAND EAST AND NORTHEASTWARD THIS
AFTERNOON. HAVE SHIFTED WINDOW FOR STRONGER STORMS IN TERMINALS
LATER INTO THE AFTERNOON. A FEW OF THE HIGH RES MODELS INDICATING
ANOTHER POSSIBILITY OF SHRA/TSRA DEVELOP OVERNIGHT NEAR CLL/UTS
06Z AND FOR IAH/HOU/SGR/LBX 10-15Z BEFORE STRONGER STORMS ARRIVE
IN THE AFTERNOON FRIDAY WITH 3000+ CAPE/-8 TO -11 LI...SAVING
GRACE MAY BE THE RELATIVELY LIGHT WIND PROFILE BUT STILL PLENTY OF
VEERING IN THE LL. 45

&&

PREV DISCUSSION... /ISSUED 529 AM CDT THU APR 16 2015/

DISCUSSION...
RATHER QUIET ACROSS SE TX THIS MORNING BUT CHANGES ARE EXPECTED AS
THE DAY WEARS ON. AS ANOTHER SHORTWAVE APPROACHES FROM THE WEST...
ACTIVITY SHOULD BEGIN DEVELOPING OVER THE COASTAL WATERS ALONG THE
WARM FRONT LATER THIS MORNING. AS THE FRONT LIFTS NORTH INTO SE TX
THE APPROACH/PASSAGE OF THE STRONG S/WV WILL HELP TO SPREAD STORMS
INLAND DURING THE AFTN. HIGH PWS/FAVORABLE WIND PROFILE AND AN UNSTABLE
AIRMASS OVER THE CWA WILL SUPPORT THE DEVELOPMENT OF STRONG TO SEVERE
STORMS EMBEDDED WITHIN THE PCPN THAT DOES FORM. DAMAGING WINDS AND
LARGE HAIL WILL BE THE MAIN THREATS. ADDITIONALLY...CANNOT RULE OUT
THE THREAT OF FLASH FLOODING THIS AFTN AS GROUNDS ARE SATURATED FROM
THE RAINS OF LATE.

NO REAL RESPITE FROM THE STORMY WX AS WE HEAD INTO FRI. MODELS ARE
EVEN MORE BULLISH WITH THE LIKELIHOOD OF SEVERE WX/HEAVY RAINS
FOR THE REGION. THE LINGERING WARM FRONT...A STILL VERY MOIST/UNSTABLE
AIRMASS AND LIKELY BETTER UPPER JET DYNAMICS ALL CONTRIBUTING TO A
CONTINUATION OF THE MENTION OF SEVERE/HEAVY RAINS IN THE WX GRIDS.
SOME LINGERING ACTIVITY ON SAT WITH DRYING/CLEARING CONDITIONS SUN
AS THE MAIN UPPER LOW FINALLY (!!!) LIFTS OUT TO THE E/NE. THE
ENSUING NWLY FLOW ALOFT WILL HELP TO PUSH A COLD FRONT OFF THE
COAST LATE SUN/EARLY MON. IF EXTENDED GUIDANCE HAS ITS WAY NEXT
WEEK MAY SEE THE RETURN OF THE ACTIVE SRN STREAM JET FOR SE TX. 41

MARINE...
WINDS VARYING DRAMATICALLY ACROSS THE COASTAL WATERS...LIGHT
EASTERLY IN THE BAYS TO EAST-SOUTHEAST WELL OFFSHORE AND STRONGER.
THE STRONGER WINDS APPEAR TO BE SOUTH OF THE WARM FRONT. SCATTERED
SHOWERS AND THUNDERSTORMS ONGOING NEAR THE BOUNDARY WITH STRONGER
STORMS SOUTH OF THE COASTAL WATERS. THAT MAY WELL CHANGE LATE THIS
MORNING AND AFTERNOON AS WARM FRONT LIFTS INLAND AND NEXT AND MORE
POTENT S/W ARRIVES. STRONG TO SEVERE STORMS POSSIBLE TODAY WITH
STRONG WINDS AND AGAIN FRIDAY. FLOW BECOMES SE AND GETS TO AROUND
10- 15 KNOTS AND STAYS THERE ON FRIDAY WITH A SLOW BUILDING OF
SEAS. MODELS STILL CONSISTENT WITH A COLD FRONT ARRIVING IN THE
COASTAL WATERS EARLY MONDAY. INTERESTINGLY THE 06Z RUN OF THE NAM
DEVELOPS A BIG CLUSTER OF STORMS WELL IN ADVANCE OF THE FRONT AND
RACES THEM INTO THE COASTAL WATERS EARLY SUNDAY. MARINERS
CONSIDERING GOING OFFSHORE THE NEXT FEW DAYS SHOULD KEEP UP TO
DATE ON THIS UNSETTLED AND ACTIVE WEATHER PATTERN THE REGION HAS
FALLEN INTO AND PLAN ACCORDINGLY. 45

&&

AVIATION...
WINDS ARE BACKING TO THE EAST ALONG THE COAST WITH COASTAL
TROUGHING. MVFR CIGS/VIS CAME IN EARLY AND HAVE DISSIPATED FOR THE
MOST PART - WARM FRONT LOOKS TO BE JUST OFFSHORE AND SHOULD LIFT
BACK NORTH THROUGH MOST OF THE AREA TODAY. ATMOSPHERE BECOMES
UNSTABLE THIS AFTERNOON AND CAP ERODES SETS THE STAGE FOR
SCATTERED SHRA/TSRA SOME +TSRA POSSIBLE WITH GUSTY WINDS THE
GREATER THREAT BUT CAN`T RULE OUT SOME HAIL. 18-23Z LOOKS TO BE
THE WINDOW FOR GREATEST THREAT FOR TSRA AT CXO-IAH-HOU--SGR-LBX-
GLS TERMINALS TODAY. EROSION OF THE CAP POSSIBLE AROUND 17Z BUT
STRONGER STORMS MAY HOLD OFF UNTIL MID AFTERNOON AS SOUTHERN
STREAM S/W AND NOSE OF THE UPPER JET IMPINGE ON THE AREA. STORMS
SHOULD DEPART OFF THE EAST AFTER 00Z AS UPPER JET STRENGTHENS AND
AXIS SHIFTS NORTH TO AROUND CLL-UTS. MOISTURE RETURN CONTINUES
OVERNIGHT AND MIGHT GET SOME MVFR CIGS BUT WILL PROBABLY JUST
CARRY SCT DECKS. FRIDAY AFTERNOON COULD BE A MESS WITH THE NEXT
SIGNIFICANT ROUND OF STRONG AND SEVERE THUNDERSTORMS...UPPER
DIFFLUENCE LOOKS FAR BETTER FOR AIDING STORM DEVELOPMENT...IMPACTS
FROM SAT-FTW-HOU IN THE OFFING. 45

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      76  66  76  65  79 /  70  50  60  60  40
HOUSTON (IAH)              76  67  76  66  80 /  70  50  60  60  40
GALVESTON (GLS)            74  70  74  69  76 /  70  50  60  60  40

&&

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

$$

DISCUSSION...31/43


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