Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 250327
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1027 PM CDT SUN MAY 24 2015

.DISCUSSION...
SATELLITE IMAGERY SHOWING MOSTLY CLEAR CONDITIONS FOR THE TIME
BEING. WITH MOIST ONSHORE FLOW WOULD EXPECT LOW STRATOCUMULUS
DECK TO DEVELOP OVERNIGHT WITH A FEW STREAMER SHOWERS OR
THUNDERSTORMS POSSIBLE SO HAVE GONE WITH JUST A 20 PERCENT CHANCE
OF RAIN AND SKY BECOMING MOSTLY CLOUDY OVERNIGHT. LOWERED MIN
TEMPS A TAD AS ALREADY OBSERVING TEMPERATURES CLOSE TO FORECAST
MINS. WITH TEMPS NEAR THE DEWPOINTS SOME PATCHY FOG IS POSSIBLE IN
SHELTERED AREAS...BUT THINK BOUNDARY LAYER FLOW WOULD SUPPORT MORE
OF A LOW STRATUS DECK THAN FOG.

STILL ON TRACK FOR STORMS ON MONDAY AND MONDAY NIGHT. SOME
UNCERTAINTY IN HOW MUCH RAIN WILL FALL. THIS WILL DEPEND ON HOW
PROGRESSIVE/FAST MOVING THUNDERSTORM COMPLEX IS. IF IT TRACKS
QUICKLY LIKE THIS MORNINGS STORMS...ANY FLOODING WOULD BE MORE THE
NUISANCE VARIETY. IF TRAINING OF CELLS OR REDEVELOPMENT BEHIND
INITIAL LINE WERE TO OCCUR FLOODING COULD BE MORE SIGNIFICANT.
FLASH FLOOD WATCH IS AN INDICATION OF THE POTENTIAL FOR FLOODING
GIVEN THE SATURATED SOILS...ELEVATED STREAM FLOWS AND POTENTIAL
FOR HIGH RAIN RATES...BUT STILL SOME UNCERTAINTY.

IT DOES APPEAR THAT SEVERE THREAT MIGHT BE A TAD HIGHER THAN WITH
THIS MORNINGS STORMS...GIVEN MORE FAVORABLE TIME OF DAY AND MORE
INSTABILITY...WHILE CONTINUING WITH FAVORABLE SHEAR PROFILES.

46

&&

.PREV DISCUSSION... /ISSUED 622 PM CDT SUN MAY 24 2015/

AVIATION...
CLOUDS ARE IN THE PROCESS OF MOVING EASTWARD AND OUT OF THE AREA. COULD
SEE SOME MVFR CEILING AND POSSIBLE FOG DEVELOPMENT AT SOME OF THE SITES
OVERNIGHT. GOING WITH VCSH FOR POSSIBLE MID MORNING SHOWER DEVELOPMENT...
THEN TSRA FOR THE AFTERNOON HOURS AS THE NEXT BATCH OF SHRA/TSRA DEVELOPS
AND MOVE ACROSS THE AREA. THINGS QUIET DOWN TOMORROW EVENING AS ACTIVITY
COMES TO AN END.  42

PREV DISCUSSION... /ISSUED 344 PM CDT SUN MAY 24 2015/

DISCUSSION...
SEEING SOME SCT TSRA REDEVELOP ACROSS N PARTS OF THE AREA WHERE
HEATING AND RRQ OF DEPARTING JET ARE WORKING THEIR MAGIC.
ANTICIPATE THESE TO TAPER OFF SHORTLY AFTER SUNSET. IN THE
MEANTIME...CAN STILL SEE SOME ISO STRONG STORMS/DOWNPOURS THAT`LL
NEED TO BE MONITORED.

OVERNIGHT SYSTEM MADE MUCH QUICKER EWD PROGRESS THAN EXPECTED
YDAY AND IS WELL INTO CNTL LA. (FASTER NAM12 ACTUALLY DID A
RESPECTABLE JOB). ALSO SEE NO LINGERING SFC BOUNDARY ALONG I-10
ON CURRENT SFC OBSERVATIONS THAT SOME MODELS WERE INDICATING FOR
TONIGHT - SERVING AS A FOCUS FOR POSSIBLE OVERNIGHT CONVECTION AS
ONSHORE FLOW AND LLJ FEEDS INTO IT. ONLY CANADIAN AND POSSIBLY LATER
SPC HRRR RUNS DEPICT SUCH A SCENARIO NOW - THE REST (INCLUDING
ECMWF) KEEP THE REGION MOSTLY DRY OVERNIGHT. THIS GIVES US A BIT
MORE CONFIDENCE IN A DRIER OVERNIGHT PERIOD THAN EARLIER - BUT
STILL NO GUARANTY. HAVE SLIGHTLY LOWERED POPS IN RESPONSE.

NEXT IMPULSE SEEN ON W/V IMAGERY IN SRN NEVADA WILL MOVE ACROSS
THE STATE MONDAY. EXPECT THIS DISTURBANCE TO TRIGGER ANOTHER SHOWER AND
THUNDERSTORM COMPLEX TO OUR WEST. THIS SYSTEM SHOULD BE MOVING
INTO WESTERN PARTS OF THE AREA TOWARD MID MORNING AND ACROSS THE
REMAINDER OF THE REGION THROUGH THE AFTERNOON HOURS. ISSUED
ANOTHER FF WATCH FROM MID MORNING INTO THE EVENING MON FOR
LOCATIONS GENERALLY ALONG AND NORTH OF I-10. THERE IS SOME UNCERTAINTY
REGARDING HOW FAST THE SYSTEM WILL MOVE OUT AND SOME LOCATIONS
MIGHT SEE PRECIPITATION CONTINUE INTO THE EVENING. IN GENERAL...EXPECT
1 TO 3 INCH RAINFALL AMOUNTS IN THE WATCH AREA AND LESS SO FURTHER
SOUTH. LOCALIZED HIGHER TOTALS ARE POSSIBLE WHERE TRAINING CELLS
OCCUR...AND ALSO IF THE EVENT DRAGS ON INTO THE EVENING HOURS.
THIS WATCH WILL NEED TO BE EXPANDED IN TIME IF IT DOES.

IN ADDITION TO TRAINING STORMS...DYNAMICS W/ THIS SYSTEM ALSO
LOOK FAVORABLE FOR SOME STRONG/SEVERE STORMS WITH WIND DAMAGE AND
TORNADOES BEING THE PRIMARY THREAT. GROUNDS ARE WET AND TREES ARE
MORE PRONE TO BE BLOWN DOWN WITH LESS INTENSE WINDS THAN THEY
MIGHT OTHERWISE.

SPOKE ABOUT THE UNCERTAINTY ABOUT MON NIGHT REGARDING TIMING OF
THE EXIT OF PRECIP. WILL JUST NEED TO WATCH TRENDS. REMAINDER OF
THE WORK WEEK WOULD ANTICIPATE SCT (MAINLY AFTN/EVNG) PRECIP EACH
DAY ACROSS INLAND AREAS. ANOTHER TROF APPROACHES THE NEIGHBORHOOD
GOING INTO NEXT WEEKEND...ALONG W/ HIGHER POPS UNFORTUNATELY. 47

MARINE...
LOOKS LIKE A REPRISE FROM WIDESPREAD THUNDERSTORMS OVER THE BAYS AND
GULF WATERS UNTIL AT LEAST LATER TONIGHT AND LIKELY UNTIL MONDAY.
THE PRESSURE GRADIENT LOOKS TO WEAKEN A BIT TONIGHT...BUT THEN
TIGHTEN BACK UP ON MONDAY BEFORE WEAKENING AGAIN MONDAY EVENING. FOR
THE MOST PART EXPECT ADVISORY CONDITIONS THROUGH MONDAY
AFTERNOON...ALTHOUGH THE WINDS COULD DIMINISH SLIGHTLY BELOW 21
KNOTS TONIGHT AT LEAST OVER THE BAYS AND NEARSHORE WATERS.

REGARDING THE TIDES...GALVESTON CHANNEL AND THE NORTH JETTY BOTH
RECORDED TIDE LEVELS OF ABOUT REACHED ABOUT 1.2 FEET ABOVE NORMAL
LEVELS DURING THE TIME OF THE ASTRONOMICAL HIGH TIDE EARLIER TODAY.
TIDE LEVELS ARE EXPECTED TO BE SLIGHTLY LOWER LATE TOMORROW MORNING
DURING THE HIGH TIDE TIME. EVEN SO...WAVE RUN UP COULD STILL PRESENT
SOME PROBLEMS WITH MINOR FLOODING ON LOW LYING AREAS ALONG THE GULF
FACING BEACHES OF THE BOLIVAR PENINSULA FROM LATE MORNING TO EARLY
AFTERNOON ON MONDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      72  84  71  87  74 /  20  90  70  30  20
HOUSTON (IAH)              72  84  72  87  74 /  20  80  60  40  20
GALVESTON (GLS)            76  84  78  85  78 /  20  80  60  20  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...FLASH FLOOD WATCH FROM 10 AM CDT MONDAY THROUGH MONDAY EVENING
     FOR THE FOLLOWING ZONES: AUSTIN...BRAZOS...BURLESON...
     COLORADO...GRIMES...HARRIS...HOUSTON...LIBERTY...MADISON...
     MONTGOMERY...POLK...SAN JACINTO...TRINITY...WALKER...
     WALLER...WASHINGTON.

     HIGH RIP CURRENT RISK THROUGH MONDAY EVENING FOR THE FOLLOWING
     ZONES: BRAZORIA...CHAMBERS...GALVESTON...MATAGORDA.

GM...SMALL CRAFT ADVISORY UNTIL 7 PM CDT MONDAY FOR THE FOLLOWING
     ZONES: GALVESTON BAY...MATAGORDA BAY...WATERS FROM FREEPORT
     TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM
     FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS
     FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM...WATERS FROM HIGH
     ISLAND TO FREEPORT OUT 20 NM.

&&

$$

DISCUSSION...99


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