361
FXUS64 KHGX 210012
AFDHGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
612 PM CST MON JAN 20 2025
..NEW AVIATION
SHORT TERM
(THIS EVENING THROUGH TUESDAY NIGHT)
ISSUED AT 303 PM CST MON JAN 20 2025
*** HISTORIC WINTER STORM TO IMPACT SE TEXAS ***
KEY MESSAGES:
1) DETERIORATING CONDITIONS ARE EXPECTED OVERNIGHT WITH MODERATE
TO HEAVY MIXED PRECIPITATION TOMORROW MORNING AND EARLY AFTERNOON.
2) SNOW TOTALS OF 4-6" ALONG AND SOUTH OF THE I-10 CORRIDOR, 1-3"
NORTH OF THE I-10 CORRIDOR AND SW OF THE HOUSTON METRO. HIGHER
AMOUNTS ARE POSSIBLE IN THE STRONGEST BANDS. ICE ACCUMULATIONS OF
UP TO 0.1" POSSIBLE.
3) EXTREMELY COLD TEMPERATURES ARE EXPECTED ON TUESDAY NIGHT,
WITH LOWS NEAR OR BELOW 20 DEGREES.
4) TRAVEL WILL BE EXTREMELY HAZARDOUS AND NOT POSSIBLE AT TIMES.
DRIVING SHOULD BE AVOIDED IN IMPACTED AREAS UNTIL CONDITIONS
BECOME SAFER.
CONFIDENCE HAS CONTINUED TO INCREASE IN THE PROSPECT OF A
HISTORIC WINTER STORM TO IMPACT THE AREA OVERNIGHT TONIGHT INTO
TOMORROW AFTERNOON. BASED ON THE CURRENT FORECAST, THIS WILL BE
THE MOST SIGNIFICANT WINTER STORM THE GREATER HOUSTON AREA HAS
EXPERIENCED SINCE AT LEAST 1960. THIS IS A HIGHLY UNUSUAL EVENT
FOR OUR REGION THAT WILL PRODUCE VERY HAZARDOUS TRAVEL CONDITIONS
THROUGHOUT THE COURSE OF THE DAY TOMORROW AND INTO THE EARLY
PARTS OF WEDNESDAY. AS SUCH, IT MUST BE STRESSED THAT TRAVEL
SHOULD BE AVOIDED AT ALL COSTS UNTIL CONDITIONS BECOME SAFER.
SYNOPTIC MODELS CONTINUE TO REMAIN ON TRACK WITH THEIR DEPICTION
OF A WEAK COASTAL LOW/TROUGH IN THE WESTERN GULF THAT WILL
CONTINUE TO PUSH NORTHEASTWARD TONIGHT AND INTO TOMORROW. AS THIS
OCCURS, AN AMPLIFIED MIDLEVEL TROUGH WILL PUSH INTO THE SOUTHERN
PLAINS BY TOMORROW MORNING. GLOBAL MODELS ALSO PLACING SE TX
WITHIN THE RIGHT ENTRANCE REGION OF A STRONG JET STREAK, THEREBY
PROVIDING FAVORABLE CONDITIONS FOR VERTICAL ASCENT/UPPER LEVEL
DIVERGENCE AS THE SYSTEM APPROACHES THE SE TX COAST.
LATEST GUIDANCE INDICATES THE ONSET OF PRECIPITATION AS EARLY AS
6 PM THIS EVENING ACROSS PARTS OF THE NORTHERN ZONES. INITIAL
LIGHT PRECIPITATION IS EXPECTED TO FALL AS COLD RAIN OR A MIX OF
RAIN, SLEET, AND SNOW AS TEMPERATURES COOL BELOW FREEZING OVER THE
COURSE OF THE OVERNIGHT PERIOD. THIS COULD AMOUNT TO SOME
MEASURABLE SNOW AND/OR SLEET BEFORE MIDNIGHT, PARTICULARLY ACROSS
LOCATIONS TO THE NORTH OF THE I-10 CORRIDOR.
MORE SIGNIFICANT PRECIPITATION WILL BEGIN AFTER MIDNIGHT AND
LIKELY PEAK BETWEEN APPROXIMATELY 6 AM AND NOON TOMORROW AS THE
AFOREMENTIONED LOW PRESSURE SYSTEM PUSHES CLOSER TO THE COAST.
CONFIDENCE REMAINS HIGH THAT MOST OF THIS PRECIPITATION WILL FALL
AS SNOW. HOWEVER, WE COULD SEE PERIODS OF A WINTRY MIX DEPENDING
ON RELATIVELY SMALL FLUCTUATIONS IN THE TEMPERATURE PROFILE OVER
THE COURSE OF THE EVENT. AREAS SW OF THE HOUSTON METRO, WHERE
FORECAST SOUNDINGS INDICATE A MORE ROBUST LAYER OF WARM AIR ALOFT,
MAY PICK UP SOME FREEZING RAIN DURING THIS TIME PERIOD WITH TOTAL
ICE ACCUMULATIONS BETWEEN A HUNDREDTH AND A TENTH OF AN INCH.
BETWEEN TODAY'S SUITE OF GLOBAL MODEL GUIDANCE, HIGH RESOLUTION
MODELS, AND PROBABILISTIC ENSEMBLE GUIDANCE, OUR FORECAST
SNOWFALL TOTALS HAVE EXPERIENCED A SLIGHT SHIFT TO THE SOUTH BUT
OTHERWISE HAVE REMAINED GENERALLY ON TRACK FROM THE PAST FEW
FORECAST PACKAGES. THE HEAVIEST SNOWFALL CONTINUES TO REMAIN
CONCENTRATED ALONG AND SOUTH OF THE I-10 CORRIDOR, PARTICULARLY
THE SOUTHERN PORTION OF METRO HOUSTON, GALVESTON BAY AREA, AND THE
GALVESTON ISLAND AREA. WIDESPREAD TOTALS OF 4-6" OF SNOWFALL ARE
EXPECTED TO FALL IN THESE LOCATIONS, WITH THE REST OF SE TEXAS
LIKELY TO SEE 1-3" OF SNOWFALL. MESOSCALE MODELS CONTINUE TO SHOW
THE POTENTIAL OF A FEW HEAVIER BANDS OF SNOW, AND AS SUCH WE COULD
SEE SOME LOCALIZED AMOUNTS HIGHER THAN 6 INCHES. WINTER
PRECIPITATION SHOULD GENERALLY CLEAR FROM NORTH TO SOUTH, WITH
PRECIPITATION ENDING DURING THE EARLY AFTERNOON HOURS. THE
TEMPERATURE FORECAST TOMORROW IS COMPLICATED, AND WILL BE TIED TO
THE TIMING AND LOCATION OF ANY SNOWFALL. MOST LOCATIONS WILL HAVE
THE POTENTIAL TO BREAK ABOVE FREEZING, IF ONLY SLIGHTLY, BUT
THERE'S A CHANCE SOME AREAS MAY REMAIN AT OR BELOW FREEZING FOR
THE ENTIRE DAY. MORE CLARITY ON THIS MAY NOT ARRIVE UNTIL WE ARE
WELL INTO THE EVENT TOMORROW.
FORECAST SNOW TOTALS CERTAINLY STAND OUT IN A HISTORICAL CONTEXT.
WHILE WE WILL NOT BREAK THE ALL-TIME SNOWFALL RECORD FOR HOUSTON
(14" IN 1895), A TOTAL OF HIGHER THAN 3" WOULD SURPASS THE 1960
WINTER STORM AS THE SECOND HIGHEST SNOWFALL TOTAL IN RECORDED
HISTORY FOR HOUSTON. AS THE FORECAST STANDS, THIS SHOULD BE
CONSIDERED A GENERATIONAL WINTER STORM EVENT AND ITS IMPACTS
SHOULD BE TAKEN SERIOUSLY. TRAVEL OVERNIGHT AND TOMORROW WILL BE
EXTREMELY HAZARDOUS IF NOT IMPOSSIBLE FOR MUCH OF THE AREA, AND
TRAVEL IS HIGHLY DISCOURAGED. ROADS WILL BECOME SLICK AND
DIFFICULT TO DRIVE ON, WITH ICING POSSIBLE ON ELEVATED ROADWAYS
AND BRIDGES.
WE CONTINUE TO ALSO ANTICIPATE A VERY COLD MORNING ON WEDNESDAY,
WITH THE COMBINED IMPACTS OF COLD ADVECTION AND A LINGERING
SNOWPACK BRINGING OVERNIGHT LOWS TO NEAR OR BELOW 20 INLAND AND IN
THE MID 20S ALONG THE IMMEDIATE COAST. LOW TEMPERATURES WILL BE
SUBJECT TO THE LOCATION OF WHERE THE HEAVIEST SNOW FALLS, AND
POSSIBLE UPWARD/DOWNWARD ADJUSTMENTS IN THE FORECAST WILL BE
REQUIRED ONCE A BETTER PICTURE OF THE SNOWPACK EMERGES. AS SUCH,
WE HAVE MAINTAINED THE EXTREME COLD WATCH FOR NOW, AS SOME AREAS
STILL ARE POISED TO REACH WIND CHILLS OF 10-15 DEGREES DURING THE
EARLY PART OF WEDNESDAY. THE LIKELY LOCATIONS OF THE COLDEST
LOWS/WIND CHILLS SHOULD EMERGE TOMORROW AFTERNOON. REGARDLESS,
THESE COLD TEMPERATURES WILL ALLOW FOR ACCUMULATED PRECIPITATION
TO REMAIN ON SURFACES/ROADWAYS AND ALSO MAY RESULT IN REFREEZING
OF ANY LINGERING LIQUID.
PREPARATIONS FOR THIS HISTORIC STORM SHOULD BE FINALIZED AS SOON
AS POSSIBLE. BE PREPARED TO POTENTIALLY NEED TO STAY WHERE YOU
ARE THROUGHOUT THE DAY ON TUESDAY AND INTO EARLY WEDNESDAY AS
TRAVEL CONDITIONS MAY NOT BE SAFE. BE SURE TO CONSIDER ANY FINAL
ACTIONS NEEDED TO PROTECT THE "4 PS" - PEOPLE, PLANTS, PETS, AND
PIPES.
CADY
LONG TERM
(WEDNESDAY THROUGH NEXT SUNDAY)
ISSUED AT 303 PM CST MON JAN 20 2025
WE WILL KICK OFF THE LONG-TERM FORECAST WITH THE MENTION OF THE VERY
COLD TEMPERATURES EXPECTED WEDNESDAY MORNING. LOWS ON WEDNESDAY
MORNING WILL BE IN THE TEENS FOR INLAND AREAS AND IN THE LOW 20S
ALONG THE COAST. WIND CHILLS WILL BE FLIRTING WITH THE CRITERIA FOR
AN EXTREME COLD WARNING. LOCAL CRITERIA FOR THE EXTREME COLD WARNING
IS WIND CHILLS OR AIR TEMPERATURES OF 15F OR LESS FOR HARRIS
COUNTIES AND COUNTIES SOUTH OF HARRIS. FOR THOSE NORTH OF HARRIS
COUNTY THE CRITERIA IS 10F OR LESS.
THAT BEING SAID, WE ARE GOING TO STICK WITH THE EXTREME COLD WATCH
FOR THE TIME BEING AND CONSIDER UPGRADING TO AN EXTREME COLD WARNING
WITH THE OVERNIGHT PACKAGE OR DURING THE DAY TUESDAY. THESE COLDER
TEMPERATURES ARE HEAVILY DEPENDENT ON WHERE THE BULK OF SNOW/ICE
FALLS.
ROAD CONDITIONS WILL LIKELY REMAIN HAZARDOUS WEDNESDAY MORNING,
ESPECIALLY SINCE TEMPERATURES ON TUESDAY WILL STRUGGLE TO GET ABOVE
FREEZING FOR MOST LOCATIONS (IF THEY DO REACH TO ABOVE FREEZING, IT
WOULDN'T BE FOR LONG). THAT MEANS WHATEVER MELTING DOES OCCUR, AND
WHATEVER IS STILL FROZEN WILL REFREEZE/REMAIN FROZEN WITH THE
SUBFREEZING TEMPERATURES TUESDAY NIGHT INTO WEDNESDAY MORNING.
LUCKILY, WE ARE EXPECTED TO GET INTO THE 40S ACROSS THE AREA
WEDNESDAY AFTERNOON, SO THIS SHOULD IMPROVE TRAVEL CONDITIONS DURING
THE AFTERNOON HOURS. BE MINDFUL THAT ANY RESIDUAL WET SPOTS ON
ROADWAYS/BRIDGES/OVERPASSES WILL REFREEZE WEDNESDAY NIGHT AS WE DIP
BACK INTO SUBFREEZING TEMPERATURES.
NEAR THE END OF THE WEEK AN UPPER LEVEL TROUGH WILL DEEPEN FROM THE
FOUR CORNERS AND WILL EJECT ANOTHER COLD FRONT TOWARDS SE TEXAS.
FEAR NOT, DESPITE ANOTHER COLD FRONT TEMPERATURES ARE STILL EXPECTED
TO GRADUALLY WARM AS ONSHORE FLOW QUICKLY RETURNS LATE FRIDAY INTO
EARLY SATURDAY. ALL IN ALL, FREEZING TEMPERATURES AT NIGHT/EARLY
MORNING SHOULD COME TO AN END THURSDAY NIGHT INTO FRIDAY MORNING.
FRIDAYS LOWS WILL BE MUCH WARMER AS TEMPERATURES JUMP INTO THE
UPPER 30S TO LOW 40S. BY THE WEEKEND, LOW TEMPERATURES WILL BE IN
THE 50S.
SIMILARLY, HIGHS WILL SEE A SIMILAR UPWARD TREND WITH HIGHS IN THE
60S OVER THE WEEKEND. WITH THE RETURN OF ONSHORE FLOW, WE WILL ALSO
SEE THE RETURN OF MOISTURE AHEAD OF THE NEXT FRONTAL BOUNDARY. THIS
WILL RESULT IN AN INCREASED CHANCE OF SHOWERS OVER THE WEEKEND. WITH
IT BEING LATER IN THE PERIOD THERE IS UNCERTAINTY ON WHETHER OR NOT
THE FRONT WILL PUSH THROUGH THE AREA. AT THE VERY LEAST, MODEL
CONSENSUS IS STILL TRENDING TO A RAINY WEEKEND.
ADAMS
AVIATION
(00Z TAF ISSUANCE)
ISSUED AT 556 PM CST MON JAN 20 2025
A COASTAL LOW OVER WESTERN GULF WILL CONTINUE TO SUPPLY MOISTURE
INTO THE REGION TONIGHT AND RESULT IN WINTRY PRECIPITATION
SPREADING ACROSS SE TX. SOME REPORTS OF -PL HAVE ALREADY BEEN
REPORTED AROUND IAH AREA. WE ARE EXPECTING A COMBINATION OF LIGHT
RA/SN/PL/FZRA OVERNIGHT INTO TUES MORNING. EXPECT CIGS TO
CONTINUE TO LOWER TO MVFR TONIGHT WITH NE WINDS INCREASING TO
10-15 KTS WITH HIGHER GUSTS OVERNIGHT INTO TUES MORNING AS THE
PRESSURE GRADIENT TIGHTENS AND AN 850MB JET DEVELOPS OVERHEAD.
WINTRY PRECIPITATION IS EXPECTED TO END BY EARLY AFTERNOON AS THE
COASTAL LOW MOVES EAST AND DRY AIR MOVES INTO SE TX. CIGS WILL
GRADUALLY IMPROVE DURING THE DAY AND WINDS WILL RELAX.
24
MARINE
ISSUED AT 303 PM CST MON JAN 20 2025
STRONG NORTHEASTERLY WINDS WILL CONTINUE THROUGH THE REST OF THE
AFTERNOON AND EVENING, WITH GUSTS TO ABOVE 30 KTS AT TIMES. GALE
CONDITIONS ARE EXPECTED TO EMERGE LATE TONIGHT, AND PEAK TUESDAY
MORNING. THE CURRENT SMALL CRAFT ADVISORY WILL UPGRADE TO A GALE
WARNING FOR ALL AREA WATERS FROM MIDNIGHT TONIGHT UNTIL EARLY
TUESDAY EVENING. CONTINUED ADVISORIES MAY BE NEEDED BEYOND THAT TIME
AS WINDS AND SEAS GRADUALLY SUBSIDE. LOW WATER LEVELS MAY BE AN
ISSUE AT TIMES AS WELL. IN ADDITION TO THESE HAZARDS A MIX OF FROZEN
PRECIPITATION IS EXPECTED ON THE BAYS AND NEAR THE COAST LATE
TONIGHT INTO TUESDAY AFTERNOON.
ADAMS
PRELIMINARY POINT TEMPS/POPS
COLLEGE STATION (CLL) 26 37 15 43 / 60 30 0 0
HOUSTON (IAH) 26 34 17 40 / 80 80 0 0
GALVESTON (GLS) 29 34 28 45 / 90 90 0 0
HGX WATCHES/WARNINGS/ADVISORIES
TX...WINTER WEATHER ADVISORY UNTIL 6 PM CST TUESDAY FOR TXZ163-164-
176.
COLD WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST TUESDAY
FOR TXZ163-164-176>179-195>200-210>214-226-227-235>238-300-
313-335>338-436>439.
EXTREME COLD WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY
MORNING FOR TXZ163-164-176>179-195>200-210>214-226-227-
235>238-300-313-335>338-436>439.
WINTER STORM WARNING UNTIL 6 PM CST TUESDAY FOR TXZ177>179-
195>200-210>214-226-227-235>238-300-313-335>338-436>439.
GM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR GMZ330-335-
350-355-370-375.
GALE WARNING FROM MIDNIGHT TONIGHT TO 6 PM CST TUESDAY FOR
GMZ330-335-350-355-370-375.
SHORT TERM...CADY
LONG TERM....ADAMS
AVIATION...COTTO (24)
MARINE...ADAMS
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