Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 261828 CCA
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
119 PM CDT TUE APR 26 2016

.AVIATION...
MVFR CIG CONDITIONS ARE FINALLY IMPROVING TO VFR THIS AFTERNOON
AND GUSTY SOUTH WINDS ARE BEGINNING TO MIX TO THE SURFACE. MOST
TERMINALS WILL BE SCT035-045 AFTER 20Z WITH SOUTH WINDS AT 15 TO
20 KNOTS.

A LARGE THUNDERSTORM COMPLEX IS DEVELOPING OVER NORTHERN TEXAS
AND OKLAHOMA THIS AFTERNOON. A STRONG CAPPING INVERSION SHOULD
LIMIT OUR CHANCES FOR ANY LOCAL CONVECTIVE ACTIVITY. HOWEVER...SEVERAL
RELIABLE SHORT-TERM MODELS SUGGEST THAT THE NORTHERN TERMINALS
COULD BE HIT BY AN OUTFLOW BOUNDARY FROM THE THUNDERSTORM COMPLEX
BETWEEN 09 AND 12Z TOMORROW MORNING. AT THIS TIME...I HAVE
MAINTAINED THE STATUS-QUO AND ONLY MENTIONED SHOWERS IN THE TAFS
BECAUSE OF THE ANTICIPATED LOW LEVEL INVERSION.

THE METEOROLOGY DEPARTMENT AT TEXAS A&M UNIVERSITY WILL BE DOING A
SPECIAL BALLOON RELEASE LATE THIS AFTERNOON TO HELP DETERMINE
WHICH MODELS HAVE THE BEST HANDLE ON THE CAP AND WHEN IT SHOULD
ERODE. THE EVENING SHIFT MAY NEED TO INTRODUCE THUNDERSTORMS IN
THE NORTHERN TERMINALS IF THE CAP PROVES TO BE WEAKER THAN
ANTICIPATED. 44

&&

PREV DISCUSSION... /ISSUED 454 AM CDT TUE APR 26 2016/

THE STATE FALLING DOWNSTREAM OF AN UPPER LOW CURRENTLY LOCATED
OVER THE LOWER GREAT BASIN. LEEWARD ROCKY MOUNTAIN PRESSURES
FALLING WITH THE 995 MB SURFACE LOW CURRENTLY SITUATED OVER SW
KANSAS...DRY LINE EMANATING FROM THE TROUGH INTO THE PANHANDLE AND
SOUTHWARD INTO THE BIG BEND REGION. THE WARM FRONT EXTENDING
EASTWARD INTO THE CENTRAL PLAINS PLACING THE MAJORITY OF THE STATE
UNDER A WARM AIR ADVECTION FLOW PATTERN. A TIGHT ONSHORE PRESSURE
GRADIENT BACK TO THE 1016 MB FLORIDA-CENTRIC HIGH IS PRODUCING A
MODERATE SOUTHERLY WIND THAT HAS AIDED IN MAINTAINING AREAWIDE LOW
70 DEW POINTS. SOUTHEASTERN U.S. MID-LEVEL RIDGING AND ROCKY
MOUNTAIN LOW HAS PRODUCED AN ENTRENCHED SOUTHWEST WIND. THIS MID-
LEVEL STEERING FLOW HAS PULLED IN A WARM AIR MASS ALOFT...NOTED BY
THE 8-9H LAYER CAPPING INVERSION IN BOTH LAST NIGHT`S CRP AND SHV
SOUNDINGS. THE EASTERN MOVEMENT OF THE GREAT BASIN 5H LOW INTO THE
(CENTRAL) WESTERN PLAINS WILL DRAW THE DRY LINE INTO CENTRAL TEXAS
TOMORROW MORNING. A QUASI-LINEAR CONVECTIVE LINE WILL LIKELY
DEVELOP ALONG THE DRY LINE THIS EVENING AND THIS LINE WILL
PROPAGATE EAST INTO NORTHEAST TEXAS THROUGH THE OVERNIGHT
WEDNESDAY MORNING HOURS. THE MODEL SUITE GENERALLY TRACKS THIS
TSRA LINE INTO THE NORTHERN FRINGES OF THE CWA BETWEEN 06 AND
12Z...BUT THE STRENGTH OF THE DOWNSTREAM CAP WILL ULTIMATELY
BECOME THE DECIDER. THE TARGET COUNTIES FOR EITHER STRONG OR
SEVERE STORMS WILL BE MADISON ..HOUSTON AND TRINITY AS THE CAP
WILL LIKELY WEAKEN THE MOST OVER THE NORTHEASTERN CWA. THE WRF-ARW
DOES HOLD A QLCS TOGETHER... POSSIBLY BOWING OUT EAST OF WACO/I-35
CORRIDOR AROUND MIDNIGHT. THE HIGHEST CONFIDENCE LIES WITH A
WEAKENING LINE THAT WILL TRAVEL ACROSS THE FORECAST AREA FROM AS
EARLY AS LATE TONIGHT THROUGH THE EARLY AFTERNOON HOURS...THE BULK
OF THE 1 TO 2 INCHES (LOCALLY 3 TO 4 INCHES) OF RAIN FALLING
DURING THE EARLY MORNING HOURS. HIGH MID-LEVEL LAPSE RATES
EQUATING TO HIGH CAPE VALUES WITH HIGH LOW LEVEL BULK SHEAR
VALUES...ALONG WITH LOWER WBZ HEIGHTS...SUGGEST THE MAIN THREATS
WILL BE WIND AND HAIL. THE PROGRESSIVE NATURE OF THE STORMS WILL
MUTE THE HIGH RAINFALL THREAT. THERE IS DECENT LOWER LEVEL VEERING
(35-45 LLJ) OF WIND THAT DOES PRODUCE A HIGHER SIGNAL FOR
TORNADOES.

THURSDAY`S VACATING UPPER LOW INTO THE GREAT LAKES REGION WILL
QUICKLY BE FILLED BY THE NEXT IN-A-LINE OF UPPER LOWS. THIS LOW
IS CURRENTLY DIVING SOUTH OUT OF THE GULF OF ALASKA AND WILL DIG
DOWN INTO THE FOUR CORNERS REGION THROUGH LATE THURSDAY INTO EARLY
FRIDAY. THIS LOW IS CURRENTLY BEING MODELED TO TAKE A SIMILAR PATH
AS TOMORROW`S LOW...MAYBE A TOUCH MORE EAST THAN NORTH. THIS WILL
CREATE BETTER UPPER LEVEL DIFFULENCE OVER THE ARKLATEX REGION
(THAN TOMORROWW`S SYSTEM)...AND THIS COULD BE THE MARKER THAT
MAKES SATURDAY`S SYSTEM A POTENTIALLY STRONGER SYSTEM. BUT IN NOT
PUTTING THE CART BEFORE THE HORSE...PRECIPITATION CHANCES WILL BE
ON THE RISE FRIDAY WITH A TIGHTENED ONSHORE PRESSURE GRADIENT
PRODUCING A ROBUST 15-20 KT SOUTHERLY SURFACE WIND. HIGHER POCKETS
OF PVA AHEAD OF THE DESERT SOUTHWEST LOW SUGGEST THAT FRIDAY COULD
BE PLAGUED WITH PERIODS OF SCATTERED SHOWERS AND STORMS. THE ONE
INHIBITOR WOULD AGAIN BE THE STRENGTH OF THE MID-LEVEL WARM NOSE.
THE FORECAST CALLS FOR ANOTHER QLCS PASSAGE SATURDAY WITH PROFILES
DEPICTING WIND AND HIGH RAINFALL RATES AS POTENTIALLY HIGHER THREATS.

UNTIL A COLD FRONT SLATED FOR THE MONDAY-TUESDAY TIME FRAME COMES
THROUGH...PERSISTENT ONSHORE FLOW WILL ENSURE THIS MUGGY AND WARM
WEATHER PATTERN THROUGH THE REMAINDER OF THE MONTH. MORNING MINIMUM
TEMPERATURES WILL RANGE IN THE UPPER 60S TO LOWER 70S WITH DAYTIME
READINGS WARMING INTO THE AVERAGE MIDDLE 80S ON DAYS WHERE IS DOESN`T
RAIN...LOWER 80S ON THOSE DAYS IT RAINS DURING THE AFTERNOON. 31

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      69  84  67  86  70 /  60  30  10  20  40
HOUSTON (IAH)              72  85  71  86  73 /  50  50  10  20  30
GALVESTON (GLS)            73  79  74  82  73 /  20  50  20  20  20

&&

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

$$

DISCUSSION...41
AVIATION/MARINE...44



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