Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 231822
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
122 PM CDT THU APR 23 2015

.DISCUSSION...
MVFR CIGS ACROSS THE REGION (EXCEPT AT GLS) SHOULD GRADUALLY LIFT
TO VFR FOR MOST SITES BY AROUND 19Z AS LL WARM AND SFC TEMPS
REACH LOWER 80S. WINDS HAVE BEEN LIGHT AND VARIABLE MOST OF THE
MORNING BUT SHOULD BECOME MORE SOUTHEASTERLY AND INCREASE TO
5-10KTS. RAIN CHANCES LOOKS TO BE HAMPERED BY MODERATE CAPPING IN
PLACE TODAY BUT COULD BE A DIFFERENT STORY TOMORROW MORNING.
OVERNIGHT INCREASE IN MOISTURE EXPECTED IN THE LL AS WEAK LLJ
FORMS AND TRAVERSES THE AREA. MVFR CIGS SHOULD BECOME MORE
WIDESPREAD AGAIN AFTER MIDNIGHT AND COULD SEE IFR PATCHY CIGS
BETWEEN 09-13Z. HAVE ADDED PROB30 FOR SHOWERS BENEATH THE CAP FOR
MOST SITES AS UPPER JET DEEPENS AND LEFT EXIT REGION OF
CYCLONICALLY CURVED JET TRAVERSES THE REGION...MAY BE TSRA TO THE
WEST OF THE AREA WEAKENING AS IT APPROACHED THE CXO/IAH/HOU/SGR
TERMINALS. ANOTHER SHORT WAVE SHOULD IMPACT THE AREA FRIDAY
NIGHT/SATURDAY MORNING BRINGING A SLIGHTLY GREATER CHANCE OF
SHRA/TSRA.

BIG EVENT FOR AVIATION IMPACTS MAY OCCUR ON MONDAY ACROSS THE
SETX AIRSPACE (POSSIBLY LONG LIVED TSRA IN THE IAH REGION).

45
&&

.AVIATION...


&&

.PREV DISCUSSION... /ISSUED 1045 AM CDT THU APR 23 2015/

DISCUSSION...
NOT A LOT OF CHANGES WITH THE MORNING UPDATE. OUR FAIRLY CAPPED
AIRMASS SHOULD HELP TO LIMIT ACTIVITY THIS AFTN EVEN AS WE STAY
UNDER THE SRN STREAM JET. 41

PREV DISCUSSION...  /ISSUED 603 AM CDT THU APR 23 2015/

UPDATE...
QUICK MORNING UPDATE TO INCLUDE PATCHY FOG MENTION. FOG HAS
DEVELOPED WHERE MID AND HIGH CLOUDS HAVE THINNED THIS MORNING...
WITH ISOLATED LOCATIONS EXPERIENCING VISIBILITIES REDUCED TO 2
MILES OR LESS. IMPROVEMENT IN CONDITIONS IS EXPECTED BY MID-
MORNING.

HUFFMAN

PREV DISCUSSION... /ISSUED 426 AM CDT THU APR 23 2015/

DISCUSSION...
RELATIVELY QUIET ACROSS SOUTHEAST TEXAS THIS MORNING... BUT
CONTINUING TO KEEP AN EYE ON A THUNDERSTORM CLUSTER MOVING EAST-
SOUTHEAST TOWARDS THE REGION AS OF 4 AM CDT. THESE STORMS MAY CLIP
THE NORTHEASTERN REACHES OF THE FORECAST AREA /ROUGHLY ALONG AND
NORTH OF A BRYAN TO LIVINGSTON LINE THROUGH THE REMAINDER OF THE
MORNING HOURS/ BUT THIS ACTIVITY EXPECTED TO WEAKEN AS THE LOW
LEVEL JET AIDING THIS COMPLEX VEERS THIS MORNING.

ANALYSIS OF 00Z UPPER AIR OBSERVATIONS PLACED THE SHORTWAVE RIDGE
AXIS JUST WEST OF THE REGION... STRETCHING THROUGH COLORADO
TOWARDS SOUTH CENTRAL TEXAS. A WEAK 500 MB SPEED MAX WAS NOTED
CROSSING THE RIO GRANDE NEAR DEL RIO AND THIS FEATURE... IN
COMBINATION WITH THE PRESENCE OF A NEAR 100 KNOT 300 MB JET OVER
THE REGION... WILL MOVE OVER THE REGION THROUGH THE DAY.

DESPITE THE PRESENCE OF SOME UPPER LEVEL LIFT AND SUFFICIENT
MOISTURE IN PLACE... THE MAJORITY OF THE AREA WILL ONLY CARRY A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS TODAY. 850 MB FLOW WILL
VEER TO THE SOUTHWEST THROUGHOUT THE DAY TODAY AS THE RIDGE
PROGRESSES EASTWARD AND THIS WILL ALLOW A CAP TO BUILD FROM
SOUTHWEST TO NORTHEAST ACROSS THE REGION... WITH 850 MB
TEMPERATURES ACROSS SOUTHEAST TEXAS RUNNING ROUGHLY 18 TO 19
DEGREES C BY MID-AFTERNOON. EVEN WITH SURFACE TEMPERATURES
EXPECTED TO BE A FEW DEGREES WARMER THAN YESTERDAY /LOW TO MID 80S
INLAND/... FORECAST SOUNDINGS FROM VICTORIA AND COLLEGE STATION
KEEP THE CAP FIRMLY IN PLACE THIS AFTERNOON. HIGH RESOLUTION
GUIDANCE DOES ATTEMPT TO BREAK OUT SOME ISOLATED SHOWERS AND
THUNDERSTORMS LATER THIS AFTERNOON OVER CENTRAL TEXAS AS A
DISTURBANCE CROSSES FROM NORTHERN MEXICO... AND SOME OF THIS
ACTIVITY MAY CERTAINLY WANDER INTO THE REGION FROM THE WEST
/COURTESY WESTERLY 850-300 MB MEAN WINDS/. WHILE A STRONGER STORM
OR TWO IS NOT OUT OF THE QUESTION... ANTICIPATE THE CAP TO WEAKEN
THE MAJORITY OF ACTIVITY THAT MOVES INTO THE REGION TODAY.

FOR TONIGHT... RAIN CHANCES WILL BEGIN INCREASING TOWARDS SUNRISE
AS AN UPPER LEVEL DISTURBANCE PRESENTLY NEAR SOUTHERN CALIFORNIA
TREKS EASTWARD. OTHERWISE... ANOTHER RELATIVELY WARM NIGHT WITH
LOW TEMPERATURES BOTTOMING OUT NEAR 70 DEGREES.

THE REGION COULD SEE A FAIRLY ACTIVE ROUND OF WEATHER ON
FRIDAY... AND THE STORM PREDICTION CENTER HAS OUTLOOKED AREAS
ALONG AND NORTH OF A CALDWELL TO LIVINGSTON LINE WITH AN ENHANCED
RISK FOR SEVERE WEATHER WITH THE REMAINDER OF THE REGION IN A
SLIGHT RISK. AS THE AFOREMENTIONED DISTURBANCE NEARS THE REGION ON
FRIDAY... IT WILL PUSH A PACIFIC FRONT THROUGH NORTH AND CENTRAL
TEXAS. LIFT AHEAD OF THE APPROACHING DISTURBANCE... COMBINED WITH
INLAND MUCAPE VALUES APPROACHING 2500 J/KG... STEEP MID-LEVEL
LAPSE RATES NEAR 7.5 C/KM... AND 50 TO 60 KNOTS OF BULK SHEAR...
LOOK TO CREATE SEVERAL ROUNDS OF THUNDERSTORMS FOR THE REGION
DURING THE DAY ON FRIDAY AND LASTING INTO THE OVERNIGHT HOURS AS
THE PACIFIC FRONT REACHES THE REGION. FORECAST SOUNDINGS ON FRIDAY
SHOW PRECIPITABLE WATER VALUES SURGING TO NEARLY 2 INCHES...
RAISING CONCERNS FOR LOCALLY HEAVY RAINFALL /AND POTENTIALLY
ISOLATED FLOODING/ WITH STRONGER CONVECTIVE ACTIVITY.

IN THE EXTENDED... THE FRONT/REMNANT BOUNDARY WILL STALL ACROSS
THE FORECAST AREA ON SATURDAY AND SERVE AS A FOCUS FOR ADDITIONAL
SHOWERS AND THUNDERSTORMS THROUGH THE FIRST HALF OF THE DAY. THE
REGION WILL BE SITUATED UNDER THE RIGHT REAR QUADRANT OF AN UPPER
JET ON SATURDAY AND... WITH THESE FAVORABLE JET DYNAMICS AND
AMPLE INSTABILITY IN PLACE... STRONG TO SEVERE THUNDERSTORMS WILL
ALSO BE POSSIBLE ON SATURDAY MORNING. MAIN AREAS OF CONCERN LOOK
TO BE ALONG THE IMMEDIATE COAST AND OVER THE COASTAL WATERS.

THE FRONT IS EXPECTED TO WASH OUT ALONG THE COAST ON SATURDAY...
BUT RAIN CHANCES WILL DIMINISH THROUGH THE REMAINDER OF THE
WEEKEND AS SUBSIDENCE AND DRIER AIR OVERSPREAD THE REGION IN THE
WAKE OF THE DEPARTING UPPER LEVEL DISTURBANCE. ANOTHER SYSTEM THEN
DROPS DOWN TOWARDS THE REGION ON SUNDAY... LEADING TO ANOTHER
PERIOD OF ACTIVE WEATHER /WITH POTENTIALLY SEVERE THUNDERSTORMS/
ON MONDAY ALONG AND AHEAD OF A COLD FRONT. THE COLD FRONT WILL
CLEAR THE REGION BY TUESDAY... WITH DRIER AND COOLER CONDITIONS
EXPECTED IN ITS WAKE BY THE MIDDLE OF NEXT WEEK.

HUFFMAN

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      85  71  84  69  87 /  30  30  50  40  20
HOUSTON (IAH)              85  73  84  73  87 /  20  20  50  50  50
GALVESTON (GLS)            80  73  79  72  79 /  20  20  40  50  50

&&

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

$$

DISCUSSION...41
AVIATION/MARINE...45



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