862
FXUS64 KHGX 171126
AFDHGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
526 AM CST FRI JAN 17 2025
..NEW AVIATION
SYNOPSIS
ISSUED AT 415 AM CST FRI JAN 17 2025
WINTER STORM AND HARD FREEZE RISK MONDAY-WEDNESDAY
KEY POINTS:
1) CHANCE OF SNOW FOR SOUTHEAST TEXAS IS INCREASING MONDAY NIGHT
THROUGH TUESDAY.
2) SNOWFALL AMOUNTS AND EXACT LOCATION OF RAIN/SNOW/MIX LINE
UNCERTAIN.
3) HARD FREEZING OVERNIGHT TEMPERATURES LIKELY ACROSS MUCH OF
SOUTHEAST TEXAS DURING THE FIRST HALF OF NEXT WEEK.
WE CONTINUE TO MONITOR THE POTENTIAL FOR A WINTER STORM ACROSS
SOUTHEAST TEXAS MONDAY NIGHT THROUGH TUESDAY. THERE ARE MANY
MOVING PARTS THAT WILL IMPACT THE AMOUNT WINTRY PRECIPITATION THAT
FALLS ACROSS THE REGION. HOWEVER, IT'S WORTH MENTIONING THAT EVEN
LIGHT SNOW / ICE TOTALS CAN RESULT IN SIGNIFICANT IMPACTS IN
SOUTHEAST TEXAS.
SHORT TERM
(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 222 AM CST FRI JAN 17 2025
HELLO, WELCOME TO THE SHORT TERM DISCUSSION - ARE YOU LOST, I'M SURE
YOU'RE PROBABLY LOOKING FOR THE LONG TERM SECTION. WELL, WHILE WHY
NOT TAKE A MOMENT AND READ THIS SECTION WHILE YOU'RE HERE? IT'S NOT
AS EXCITING AS THE WEATHER TO COME, BUT WE'VE STILL GOT SOME STUFF
GOING ON HERE, TOO.
SATELLITE SHOWS SOME HIGH CLOUDS ALREADY STREAMING OVER THE AREA
AHEAD OF AN UPPER TROUGH OVER THE GULF OF CALIFORNIA AREA, THOUGH
UPPER LEVEL RIDGING IS STILL IN PLACE OVER TEXAS...FOR NOW. AT THE
SURFACE, HIGH PRESSURE HAS BEGUN TO DRIFT EAST OF THE AREA, AND
WHILE NEAR CALM, THE LIGHT WINDS THAT ARE BEING REPORTED AROUND THE
AREA ARE NOW ONSHORE. DEWPOINTS ARE AROUND OR ABOVE 40 DEGREES
CLOSER TO THE COAST, AND THE TREND FOR INCREASED MOISTURE WILL
CONTINUE TODAY AS ONSHORE FLOW STRENGTHENS.
OF COURSE, A MOISTENING COLUMN AND STRENGTHENING ONSHORE FLOW
GENERALLY MEANS A CLOUDIER DAY, AND THAT'S LIKELY TRUE TODAY AS
WELL. BEYOND THAT, I'M ALSO EXPECTING SOME SPRINKLES, EVEN A LIGHT
SHOWER HERE OR THERE. NOT REALLY ENOUGH TO DO ANY REAL ACCUMULATING,
BUT ENOUGH TO BE NOTICED HERE AND THERE.
TEMPERATURES WILL ALSO BE A TOUCH WARMER THIS AFTERNOON IN SPITE OF
THE INCREASED CLOUD COVER. LOOK FOR HIGHS MORE IN THE UPPER 60S TO
AROUND 70, ABOVE YESTERDAY'S MID-60S.
DEWPOINTS SHOULD CONTINUE TO RISE TONIGHT, EVEN INTO THE LOWER 60S
AROUND THE COAST AND GULF. AND WITH WATER TEMPS IN THE
50S...YEAH...WE'LL WANT TO BE ON THE LOOKOUT FOR FOG TONIGHT.
WINDS WILL BE VEERING FROM SOUTHERLY TO SOUTHWESTERLY, AND THESE ARE
NOT THE MOST FAVORABLE FETCHES FOR WIDESPREAD DENSE FOG DEVELOPMENT,
SO PATCHY FOG IS LIKELY THE BETTER EXPECTATION HERE.
ANY FOG WE GET SHOULD BE SCOURED OUT BY THE ARRIVAL OF A COLD FRONT -
EXPECTED TO MOVE INTO THE AREA FROM THE NORTHWEST AFTER MIDNIGHT,
AND REACHING THE COAST TOWARDS MID-MORNING. THIS IS PROBABLY EARLY
ENOUGH FOR COOLER POST-FRONTAL AIR TO BRING LOWS DOWN TO THE LOWER
40S WAY UP IN OUR NORTHERN REACHES, BUT REMAIN IN THE UPPER 50S AT
THE GULF COAST.
THE RETURN OF A MOSTLY SUNNY SKY TOMORROW WILL HELP MITIGATE
INCOMING COLDER AIR, SO HIGHS WILL SURELY DIP, BUT PROBABLY NOT TOO
MUCH - MY NUMBERS RANGE FROM THE MID-50S TO THE MID-60S.
HOWEVER, LOWS TOMORROW NIGHT WILL START TO GET CHILLY AS COLD
ADVECTION PAIRS UP WITH MOSTLY CLEAR SKY. FORTUNATELY WINDS ARE
STILL ON THE HIGH SIDE FOR THE OVERNIGHT HOURS, SO THAT SHOULD KEEP
TEMPS FROM *REALLY* CRASHING. STILL, LOW TEMPS TOMORROW NIGHT LOOK
TO RANGE FROM THE UPPER 20S IN THE NORTH TO THE MIDDLE 30S IN
COASTAL AREAS. A LIGHT FREEZE APPEARS LIKELY NORTH OF I-10 AND THE
URBAN HEAT ISLAND OF THE METRO, AND EVEN DIPPING INTO THE RURAL
AREAS WEST OF THE METRO AS WELL. AND THIS IS JUST THE BEGINNING! BUT
FOR MORE ON THAT, READ ON TO THE LONG TERM SECTION.
LONG TERM
(SUNDAY THROUGH THURSDAY)
ISSUED AT 222 AM CST FRI JAN 17 2025
THIS LONG TERM AFD WILL BE ANOTHER TAIL OF UNCERTAINTY. BUT THIS
TIME, THE UNCERTAINTY IS LESS A QUESTION OF WHETHER OR NOT THERE
WILL BE A WINTER STORM AND MORE ABOUT SPECIFIC CHARACTERISTICS OF
THE INCREASINGLY LIKELY WINTER STORM. OVER THE LAST 24 HOURS, THE
GUIDANCE SUPPORT FOR WINTRY PRECIPITATION OVER SOUTHEAST TEXAS HAS
INCREASED SIGNIFICANTLY. THIS IS EVIDENT IN BOTH THE
DETERMINISTIC AND ENSEMBLE GUIDANCE. ONE OF THE KEYS TO THE
INCREASING CONFIDENCE APPEARS TO BE THE MODEL GUIDANCE DEPICTION
OF A STRONG MID/UPPER SHORTWAVE THAT IS EXPECTED TO DIVE SOUTHWARD
OVER W CONUS ON SUNDAY INTO MONDAY. ITS SOUTHWARD TRAJECTORY WILL
BE ALONG THE PERIPHERY OF A LONG WAVE DEEP LAYER TROUGH THAT WILL
PLACE THE WESTERN 2/3RDS OF CONUS IN A FRIGIDLY COLD PATTERN FOR
AT LEAST THE FIRST HALF OF NEXT WEEK.
THE COLD WILL BE FELT IN TIME FOR THE HOUSTON MARATHON ON SUNDAY
MORNING. MARATHON TEMPERATURES DURING THE MORNING HOURS ARE
EXPECTED TO BE IN THE 30S. THESE TEMPS WILL BE ACCOMPANIED BY
GUSTY NORTH WINDS, MAKING THE TEMPERATURE FEEL LIKE IT'S IN THE
20S. SUNDAY WILL FEATURE AMPLE SUNSHINE. BUT ROBUST CAA SHOULD
KEEP HIGHS IN THE 40S. SUNDAY NIGHT WILL BE MOSTLY CLEAR AND SUB
FREEZING.
THE AFOREMENTIONED SHORTWAVE WILL APPROACH TEXAS FROM SW CONUS ON
SUNDAY. DURING MY LAST SHIFT WEDNESDAY NIGHT INTO THURSDAY
MORNING, A SIGNIFICANT PLURALITY OF THE DATA WAS NOT AMPLIFYING
THE DISTURBANCE, THUS DENYING OUR REGION THE CRUCIAL LARGE SCALE
LIFT THAT WOULD ALLOW FOR THE DEVELOPMENT OF WIDESPREAD
PRECIPITATION. AS A RESULT, WE WERE EXPERIENCING A DRYING TREND
IN SOME OF THE DATA ALONG WITH A MODEST WARMING TREND. BUT THAT
DATA IS BEGINNING TO LOOK MORE LIKE AN ABERRATION THAN A
REASONABLE SCENARIO AT THIS POINT DUE TO INCREASING CONFIDENCE IN
THE AMPLIFICATION OF THE MID/UPPER SHORTWAVE AS IT DIVES SOUTHWARD
INTO SW CONUS BEFORE PUSHING EASTWARD TOWARDS TEXAS. THE SE TX
ATMOSPHERE WILL BEGIN TO FEEL THE TROUGH'S PVA BY MONDAY
AFTERNOON. THE RESULTING LIFT AS WELL AS ML MOISTURE SURGING
NORTHWARD WILL RESULT IN INCREASING CLOUDS AND EVENTUALLY THE
CHANCE OF A FEW RAIN AND SNOW SHOWERS.
MOISTURE AND LIFT MAXIMIZES MONDAY NIGHT INTO TUESDAY AS THE
TROUGH PUSHES INTO W TX. MEANWHILE OFFSHORE, A STEEPING BAROCLINIC
ZONE WILL LIKELY AID IN THE DEVELOPMENT OF A SURFACE TROUGH OR
LOW OFF THE TEXAS COAST. THE GRADIENT BETWEEN THE BUILDING ARCTIC
HIGH TO THE NORTH AND THE PRESSURE FALLS OVER THE GULF WILL
INCREASE NORTH TO NORTHEAST WINDS DURING THIS TIME FRAME, LIKELY
ENHANCING CAA AND POTENTIALLY RESULTING IN GALES NEAR THE COAST
AND OFFSHORE. WITH AMPLE LIFT, MOISTURE, AND CONVERGENCE, ONE HAS
TO BELIEVE THAT THERE IS A GOOD CHANCE OF PRECIPITATION ESPECIALLY
ACROSS OUR SOUTHERN AND COASTAL COUNTIES. MONDAY NIGHT - TUESDAY
POPS RANGE FROM 30-40 IN OUR FAR NORTHERN PINEY WOODS COUNTIES TO
NEAR 70 AT THE COAST (~60 IN HOUSTON). IT WAS TEMPTING TO GO EVEN
HIGHER WITH THOSE POPS FROM I-10 TO THE COAST. GIVEN THE EXPECTED
MOSTLY SUBFREEZING VERTICAL TEMPERATURE PROFILE, THE CHANCE OF
THIS PRECIP FALLING AS SNOW CONTINUES TO INCREASE. SO NOW LET'S
GET INTO THE MORE UNCERTAIN ASPECTS OF THE SYSTEM.
THERE ARE MULTIPLE FACTORS THAT WILL INFLUENCE SNOWFALL AMOUNTS.
SNOWFALL TO QPF RATIOS COULD RANGE FROM 6:1 TO AS HIGH AS 13:1.
THE LATTER VALUE IS VERY UNUSUAL IN SOUTHEAST TEXAS BUT IS
SUPPORTED BY SOME OF THE DATA. FOR OUR FORECAST, WE WENT WITH A
MORE CONSERVATIVE 6:1 NEAR THE COAST TO 8:1 FARTHER INLAND. BUT IF
WE TREND TEMPERATURES LOWER IN THE DIRECTION OF THE ECMWF, THE
RATIOS WILL NEED TO BE INCREASED. ANOTHER FACTOR IS THE SPEED OF
THE MID/UPPER TROUGH. FASTER MOVING = LESS PRECIP. SLOWER MOVING =
MORE PRECIP. FASTER MOVING WOULD NOT ONLY DECREASE SNOWFALL
TOTALS, BUT IT WOULD INCREASE THE CHANCE OF CLEARING SKIES AND
SNOW MELTING SUNSHINE TUESDAY AFTERNOON, HAVING IMPLICATIONS ON
TUESDAY'S AFTERNOON AND OVERNIGHT TEMPERATURES. THERE'S ALSO THE
COMPLEX MICROPHYSICS INVOLVED IN COMPACTION AND MELTING WHILE SNOW
IS FALLING. AND OF COURSE, THERE'S THE PROSPECT OF RAIN AND/OR
FREEZING RAIN BEING IN THE MIX (MORE LIKELY NEAR THE COAST). SO
ALTHOUGH THE RECENT TRENDS LOOK GOOD FOR FROZEN PRECIP IN
SOUTHEAST TEXAS, THERE REMAINS UNCERTAINTY REGARDING ASPECTS OF
THE MANY MOVING PARTS THAT COULD LIMIT OR ENHANCE SNOWFALL AND ICE
ACCUMULATION. THIS ALL BEING SAID, IT DOESN'T TAKE MUCH SNOW AND
ICE TO CAUSE TRAVEL ISSUES IN OUR NECK OF THE WOODS. WE ALSO LACK
THE HIGHER RESOLUTION SHORT RANGE GUIDANCE THAT MAY BETTER RESOLVE
THE BAROCLINIC ZONE AND OTHER MESOSCALE FEATURES THAT COULD
INFLUENCE THE BOUNDARY BETWEEN RAIN AND SNOW AS WELL AS THE WINDS.
I CAN'T WRITE THIS AFD WITHOUT TALKING ABOUT TEMPERATURES. HARD
FREEZE TEMPERATURES (AT OR BELOW 24F) ARE LIKELY NORTH AND WEST OF
HOUSTON SUNDAY AND MONDAY NIGHT. BY TUESDAY NIGHT, WE CANNOT RULE
OUT HARD FREEZING TEMPS ALMOST DOWN TO THE COAST. TUESDAY NIGHT'S
LOWS WILL BE HIGHLY DEPENDENT ON HOW MUCH SNOW FALLS AND DOESN'T
MELT ON TUESDAY. THE COLD IS EXPECTED TO GRADUALLY MODIFY
DURING THE SECOND HALF OF NEXT WEEK.
SELF
AVIATION
(12Z TAF ISSUANCE)
ISSUED AT 526 AM CST FRI JAN 17 2025
HIGH CLOUDS STREAMING OVERHEAD THIS MORNING, WHILE LIGHT SOUTHERLY
WINDS BEGIN TO SET UP. ONSHORE WINDS CRANK UP THROUGH THE MORNING,
BECOME 10-15 WITH GUSTS 20+ THIS AFTERNOON. EXPECTING SOME
SCATTERED SPRINKLES AND PERHAPS EVEN AN ISOLATED LIGHT SHOWER
MID-DAY TO AFTERNOON, BUT OPTING TO OMIT EVEN A PROB30 LINE FOR
NOW. ACTIVITY WILL BE SPARSE AT MOST AND CONFIDENCE OF IMPACT TO
ANY SPECIFIC TERMINAL IS VERY LOW. GUSTY WINDS CARRY INTO
EVENING AND DESPITE GUSTS, STRONG LOW LEVEL JET GIVES CAUSE FOR
LLWS MENTIONS ACROSS THE AREA. WIND SHIFT WITH FRONTAL PASSAGE IS
HINTED AT TOWARDS THE VERY END OF THE PERIOD, BUT ONLY EXPLICITLY
OCCURS IN THE IAH EXTENDED.
MARINE
ISSUED AT 222 AM CST FRI JAN 17 2025
PATCHY FOG IS POSSIBLE THIS MORNING IN THE BAYS AND NEAR THE
COAST. THERE IS A BETTER CHANCE OF PATCHY DENSE FOG THIS EVENING
FOR THE SAME AREAS AS A COLD FRONT APPROACHES. INCREASING ONSHORE
FLOW IS EXPECTED AHEAD OF THE FRONT. MODERATE TO STRONG NORTHERLY
WINDS ARE EXPECTED IN THE FRONT'S WAKE THIS WEEKEND, LIKELY
WARRANTING SMALL CRAFT ADVISORIES. WINDS ARE EXPECTED TO BECOME
MORE NORTHEASTERLY AND STRENGTHEN FURTHER EARLY NEXT WEEK,
POSSIBLY REACHING GALE CONDITIONS OVER THE GULF WATERS AND
POSSIBLY AT THE COAST AND IN THE BAYS. IN ADDITION, WE ARE
MONITORING THE GROWING POTENTIAL FOR FROZEN PRECIPITATION NEAR THE
COAST BY MONDAY NIGHT AND TUESDAY. LOW WATER LEVELS ARE POSSIBLE
SUN NIGHT INTO MID WEEK.
PRELIMINARY POINT TEMPS/POPS
COLLEGE STATION (CLL) 67 45 57 29 / 20 0 0 0
HOUSTON (IAH) 69 54 62 34 / 20 0 0 0
GALVESTON (GLS) 64 57 63 38 / 0 10 0 0
HGX WATCHES/WARNINGS/ADVISORIES
TX...NONE.
GM...NONE.
SHORT TERM...LUCHS
LONG TERM....SELF
AVIATION...LUCHS
MARINE...SELF
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