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000
FXUS64 KHGX 041117
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
517 AM CST WED DEC 4 2013

.DISCUSSION...
SIGNIFICANT WEATHER CHANGES ARE STILL FORECAST TO OCCUR OVER THIS
COMING WEEK. THE MAIN THEMES WILL BE TEMPERATURE EXTREMES AND THE
SLIGHT CHANCE FOR WEEKEND FROZEN PRECIPITATION.

SHORT TERM...WARM AND HUMID CONDITIONS THROUGH THURSDAY AS RECENT
SOUTHWESTERLY WINDS BACK MORE SOUTH-SOUTHEAST AND INCREASE LOWER-
MID-LEVEL MOISTURE. RELATIVELY HIGHER MARITIME DEW POINTS IN THE
AVERAGE UPPER 60S OVER COOLER WATER TEMPERATURES IN THE 50S WILL
BE CONDUCIVE FOR THE DEVELOPMENT OF DENSE SEA FOG OVER THE NEXT
COUPLE OF MORNINGS. INTERIOR FOG WILL BE AREAWIDE IN COVERAGE...
HIGH BASED PACIFIC MOISTURE IN THE FORM OF THICKER CIRRUS AND
NEAR 5 KNOT SOUTHERLIES WILL INHIBIT DENSE FOG. MOST INLAND LOCATIONS
WILL EXPERIENCE OVERNIGHT FOG...ALTHOUGH CALM CONDITIONS AND BREAKS
IN HE CI DECK MAY HAVE VARIOUS COMMUNITIES FALLING TO BELOW 1 SM
IN VISIBILITY.

THIS AFTERNOON WILL AGAIN BE AROUND 10-15 DEGREES WARMER THAN
NORMAL BY EARLY DECEMBER STANDARDS...MORE LATE SPRING-LIKE
WEATHER IN LATE AUTUMN OVER THE NEXT COUPLE DAYS. FOGGY...MOIST
AND MILD MORNINGS IN THE 60S WILL WARM INTO THE MEAN UPPER 70S TO
LOWER 80S ONCE AGAIN TODAY AND THURSDAY MORNING. THURSDAY WILL BE
A TRANSITION DAY WITH THE SLOW APPROACH OF THE NEXT COLD FRONT. A
SHALLOW...COLD CANADIAN AIR MASS WILL FOLLOW A THURSDAY COLD
FRONT. THIS BOUNDARY IS TIMED PASS OVER THE NORTHERN CWA DURING
THE MORNING HOURS...REACHING THE CITY BY LATE AFTERNOON. MODELS
STILL DIFFER ON THE SOUTHERN PROGRESSION OF THE SFC-925MB FRONT...
THE NAM STALLING IT NEAR THE COAST OVERNIGHT WITH THE GFS/ECMWF
SLOWLY PUSHING IT OFF INTO THE NEARSHORE WATERS LATE THURSDAY
AFTERNOON THROUGH EVENING. A STRONGER FRONTAL PUSH IS EXPECTED
FRIDAY WITH GENERALLY STEADY OR FALLING TEMPS THROUGH THE DAY. DUE
TO THIS STRONG COLD AIR ADVECTION...OVERCAST AND LIGHT PRECIPITATION...
THERE WILL NOT MUCH OF A FRIDAY AND SATURDAY DIURNAL TEMPERATURE
SWING. THE HIGHEST PROBABILITY OF RAIN WILL BE FROM LATE THURSDAY
THROUGH FRIDAY AS THE REGION WILL FALL UNDER THE BEST UPPER FORCING
OF A THE JET`S RRQ. AS OF NOW...DUE TO THE WARM SOUTHWESTERLY FLOW
ATOP THIS SHALLOW COOL DOME (EFFICIENT ISENTROPIC UPGLIDE ON THE
THETA SURFACE)...PRECIPITATION WILL BE PRIMARILY LIGHT SHOWERS AND
OR DRIZZLE.

THERE IS A SMALL POTENTIAL FOR NORTHERN COUNTY WINTER WEATHER
FRIDAY EVENING THROUGH SATURDAY MORNING (MAYBE SUNDAY MORNING?)
FREEZING DRIZZLE FRIDAY INTO SATURDAY...WITH A COLDER SURFACE
EARLY SUNDAY PROMOTING MORE OF A FREEZING DRIZZLE/RAIN SCENARIO.
THE COLD AIR MASS GETS A REINFORCING COLD SHOT FRIDAY AND...WITH
MOISTURE TRAPPED WITHIN THE NEAR SURFACE FRONTAL INVERSION LAYER
...THERE IS A SLIGHT RISK FOR EITHER NORTHERN CWA ICE PELLETS (IF
SUB FREEZING LAYER IS DEEP ENOUGH) OR FREEZING RAIN/DRIZZLE.
ISENTROPIC LIFT IS EXPECTED TO INCREASE SATURDAY WITH THE APPROACH
OF THE NEXT JET STREAK. ISENTROPIC UPGLIDE KICKS IN SATURDAY...
SUPPORTING MODEST RAIN CHANCES THROUGH THE DAY. PROG SOUNDINGS
SHOW A SIGNIFICANT WARM LAYER BETWEEN 700-900MB WITH A VERY
SHALLOW SUB-FREEZING LAYER FROM AROUND 900MB TO THE SURFACE.
WITHOUT CRITICAL THICKNESS VALUES TO SUPPORT FROZEN PRECIP AT
THIS TIME...THE CHANCE FOR FROZEN PRECIP WILL REAMIN SLIGHT...
THIS MAY ABOVE WHICH MAY BE TOO MUCH TO OVERCOME AND AKLLOW FOR
SMALL DROPLET FREEZING. ANOTHER WRENCH COULD BE THE AMOUNT (OR
LACK THEREOF) OF MID-LEVEL MOISTURE. FRIDAY NIGHT`S AIR MASS MAY
END UP NOT BEING AS DRY AS PREVIOUSLY FORECAST IN RECENT MODEL
RUNS...AND WITH ISENTROPIC LIFT LIKELY...LIQUID PRECIPITATION
BECOMES LIKELY WITH A SLIGHT RISK OF WET-BULBING THE LOWER COLUMN
OUT BELOW-FREEZING AND ULTIMATELY GENERATING A WINTRY MIX. 31

&&

.AVIATION...
WIDE RANGE OF CIGS & VISBYS ACROSS THE AREA BUT GENERAL
TREND IS DOWNWARD TOWARD IFR CONDITIONS ACROSS MOST OF THE REGION.
FCST SOUNDINGS SHOWING A STEEP LLVL INVERSION WITH MOISTURE TRAPPED
UNDER IT FOR MOST OF THE DAY. HAVE AMENDED SOME TAFS TO A MORE
PESSIMISTIC OUTLOOK WITH A DELAYED RISE TO MVFR CONDITIONS UNTIL
LATE MORNING & EARLY AFTN...AND MIGHT DO THE REMAINDER AS WELL FOR
THE 12Z TAFS. EXPECT CIGS TO AGAIN TRANSITION TO IFR LATER THIS
EVENING...ALONG WITH SOME DENSE SEA FOG ROLLING BACK IN TOWARD
SUNSET AT THE COAST.  47

&&

.MARINE...
PERIODS OF DENSE SEA FOG WILL PERSIST UNTIL THE NEXT COLD
FRONT PUSHES OFF THE COAST LATE THURS AFTN/EARLY EVENING. MODERATE
TO OCCASIONALLY STRONG OFFSHORE WINDS WILL THEN PERSIST INTO THE
EARLY TO MIDDLE PARTS OF NEXT WEEK. SMALL CRAFT ADVISORIES WILL
LIKELY BE REQUIRED FOR A GOOD PORTION OF THE FORECAST AFTER THE
FRONTAL PASSAGE.  47

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      81  64  64  36  39 /  10  10  50  70  70
HOUSTON (IAH)              81  68  74  44  45 /  10  20  50  60  70
GALVESTON (GLS)            76  67  75  54  54 /  10  20  40  60  60

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...DENSE FOG ADVISORY UNTIL 11 AM CST THIS MORNING FOR THE
     FOLLOWING ZONES: GALVESTON BAY...WATERS FROM HIGH ISLAND TO
     FREEPORT OUT 20 NM.

&&

$$

DISCUSSION...31