FXUS64 KHGX 022141
AFDHGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
341 PM CST WED DEC 2 2009
.UPDATE...
MARINE HAZARDS THROUGH THURSDAY/12Z. 31
&&
.PREV DISCUSSION... /ISSUED 324 PM CST WED DEC 2 2009/
..WINTER WEATHER POSSIBLE FRIDAY...
DISCUSSION...
CLOUDS ARE EXPECTED TO ERODE THIS EVENING LEAVING MOSTLY CLEAR
SKIES BY THURSDAY MORNING. WEAK HIGH PRESSURE WILL DOMINATE AREA
WEATHER THROUGH THURSDAY. A REINFORCING SHOT OF COOLER AIR WILL
ENTER THE REGION FRIDAY NIGHT AS A STRONGER SURGE OF HIGH
PRESSURE SINKS SOUTH.
FRIDAY:
A COMPLICATED FORECAST IS ON TAP AND A NUMBER OF DIFFERENT
SCENARIOS COULD PLAY OUT. AN UPPER LEVEL TROUGH WILL APPROACH
TEXAS FRIDAY MORNING. WINDS ALOFT WILL BECOME SOUTHWEST AND OVER
RIDE NORTHEAST SURFACE WINDS. PRECIPITATION WILL DEVELOP EARLY
FRIDAY AS LIGHT RAIN. THE THERMAL PROFILE WILL COOL QUICKLY AND
THE RAIN WILL CHANGE TO SNOW. MAX TEMPS WILL OCCUR IN THE MORNING
AND FALL THROUGH THE DAY. FORECAST SOUNDINGS ARE IN GOOD
AGREEMENT THAT THE THERMAL PROFILE WILL BE COLD ENOUGH TO SUPPORT
SNOW. THE MOST SIGNIFICANT DIFFERENCE BETWEEN THE MODELS IS IN THE
AMOUNT OF AVAILABLE MOISTURE. THE CAN/ECMWF AND UKMET ALL FAVOR
KEEPING THE MOISTURE CLOSER TO THE COAST WITH LIGHT QPF TOTALS.
THE GFS AND NAM ARE FURTHER INLAND WITH SOME HEAVIER QPF TOTALS.
FORECAST SOUNDINGS SHOW AVAILABLE MOISTURE BETWEN 0.7-0.8 INCHES
WHICH IS RATHER ROBUST IN THIS TYPE OF AIR MASS. ALSO THE MODELS
SHOW A DECENT JET COUPLET AT 300 MB. SOUTHEAST TEXAS WILL LIE IN A
RRQ OF THE POLAR JET AND IN A LFQ OF THE SUB TROPICAL JET. THIS
SHOULD ALSO ENHANCE LIFT OVER THE AREA. THE JET DYNAMICS WILL BE
IMPRESSIVE AND COULD ACTUALLY BE THE KEY TO DETERMINING HOW MUCH
PRECIPITATION WILL FALL. BOTH THE GFS AND ECMWF HAVE SHOWN GOOD
RUN TO RUN CONSISTENCY BUT NEITHER MODEL HAS AGREED WITH THE
OTHER. IF THE ISENTROPIC UPGLIDE IS AS STRONG AS THE GFS/NAM
INDICATES...SNOW WILL ACCUMULATE. IF THE WEAKER ISENTROPIC UPGLIDE
PER THE ECMWF IS CORRECT...ONLY FLURRIES SHOULD BE EXPECTED. DUE
TO THE UNCERTAINTY...WILL REFRAIN FROM ISSUING ANY WINTER WEATHER
WATCHES OR ADVISORIES. THIS IS A DEVELOPING WINTER WEATHER
SITUATION AND THERE IS A GREAT DEAL OF UNCERTAINTY. KEEP UP WITH
THE FORECASTS!
MIN TEMPS ON SATURDAY MORNING WILL BE THE COLDEST OF THE SEASON. A
FREEZE WARNING WILL BE REQUIRED FOR SAT AM OVER THE ENTIRE CWA.
ONLY THE IMMEDIATE COAST WILL BE SPARED FREEZING TEMPERATURES. LOW
TEMPS WILL FALL INTO THE LOWER AND MID 20S OVER MOST OF THE
REGION. A BRIEF WARM UP IS IN STORE FOR SUNDAY BUT TEMPS WILL
REMAIN BELOW CLIMO. ANOTHER S/WV TROUGH WILL CROSS THE SOUTHERN
PLAINS ON SUNDAY AND BRING A CHANCE OF SHOWERS TO THE REGION. THE
FIRST PART OF NEXT WEEK LOOKS QUIET WITH COOLER THAN NORMAL
TEMPERATURES AS THE FLOW ALOFT GOES ZONAL. 43
MARINE...
WEST TO NORTHWEST WINDS WILL GRADUALLY WEAKEN THROUGH EARLY
THURSDAY...AS THE BACKSIDE PRESSURE GRADIENT RELAXES BETWEEN
EXPANDING ROCKY MTN LEEWARD SIDE RIDGING AND NE'WARD EXITING LOWER
OHIO VALLEY LOW PRESSURE AREA. SEA HEIGHTS WILL FALL BACK TO AROUND
2 TO 4 FEET TOMORROW AFTERNOON UNDER 10-15 KT NORTHERLIES. A VERY
ACTIVE FRIDAY FORECAST AS A DEEPENING UPPER TROUGH ENTERS WESTERN
AND CENTRAL TEXAS. DISTURBANCES ROUNDING THE BASE OF THIS TROUGH
WILL TRAVEL OVER THE LOCAL BAY AND GULF WATERS THROUGH FRIDAY. THIS
WILL INDUCE SCATTERED SHOWERS TO WIDESPREAD RAIN WITH EMBEDDED
THUNDERSTORMS FROM EARLY FRIDAY MORNING THROUGH THE LATE EVENING. A
VIGOROUS BOUT OF VERY COLD AND DRY AIR PASSING OVER THE WATERS
BEHIND A REINFORCING COLD FRONT FRIDAY AFTERNOON WILL INCREASE
NORTHERLY WIND SPEEDS TO SCA CONDITIONS...WITH GALE FORCE GUSTS
BECOMING LIKELY LATE FRIDAY THAT MAY INITIATE REGIONAL GALE
WARNINGS. MARINERS SHOULD CLOSELY MONITOR THIS DEVELOPING SITUATION
OVER THE NEXT 24 TO 36 HOURS. 31
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 38 54 37 38 27 / 10 10 20 50 30
HOUSTON (IAH) 39 56 41 43 29 / 10 10 20 50 30
GALVESTON (GLS) 46 58 48 49 38 / 10 10 20 50 30
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR THE
FOLLOWING ZONES: MATAGORDA BAY...WATERS FROM FREEPORT TO
THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH
ISLAND TO FREEPORT OUT 20 NM.
SMALL CRAFT SHOULD EXERCISE CAUTION FROM MIDNIGHT CST TONIGHT
THROUGH LATE TONIGHT FOR THE FOLLOWING ZONES: MATAGORDA
BAY...WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM.
SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH LATE TONIGHT FOR THE
FOLLOWING ZONES: GALVESTON BAY.
SMALL CRAFT ADVISORY UNTIL 6 AM CST THURSDAY FOR THE FOLLOWING
ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO
60 NM.
&&
$$
DISCUSSION...43/31
