602
FXUS63 KPAH 172220
AFDPAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
420 PM CST MON FEB 17 2025
KEY MESSAGES
- CONFIDENCE REMAINS HIGH THAT A MAJOR WINTER STORM WILL IMPACT
THE QUAD STATE FROM TUESDAY INTO WEDNESDAY MORNING. A WINTER
STORM WARNING HAS BEEN EXPANDED EASTWARD TO ACCOUNT FOR MOST
AREAS WITH THE EXCEPTION OF OUR NORTHERN ROW OF COUNTIES IN
SOUTHERN ILLINOIS AND SOUTHWEST INDIANA.
- DANGEROUS COLD TEMPERATURES WILL CAUSE WIND CHILL VALUES TO
FALL BELOW ZERO DEGREES DURING THE LATTER HALF OF THIS WEEK
WITH THE LOWEST WIND CHILL VALUES EARLY THURSDAY MORNING.
- FLOOD WARNING REMAINS IN EFFECT UNTIL THIS EVENING FOR THE
KENTUCKY PURCHASE REGION DUE TO ONGOING FLOODING ISSUES FROM
THE RECENT HEAVY RAINFALL, WITH EXTENSIVE RIVER FLOODING
CONTINUING THIS WEEK.
DISCUSSION
ISSUED AT 206 PM CST MON FEB 17 2025
MAIN FOCUS FOR THIS DISCUSSION IS ON THE EXPECTED WINTER STORM
THAT WILL IMPACT THE QUAD STATE TUESDAY AND WEDNESDAY. SURFACE
RIDGING WILL EXTEND FROM SASKATCHEWAN THROUGH THE PLAINS WHILE
SOUTHERN ENERGY BUILDS ACROSS THE LOWER MISSISSIPPI VALLEY.
BROAD WIDESPREAD ASCENT WILL OVERSPREAD THE REGION ASSOCIATED
WITH A 120 KNOT JET STREAK ACROSS THE OHIO VALLEY WITH OUR
REGION CONVENIENTLY PLACED IN THE RIGHT ENTRANCE REGION OF THIS
JET MAX. CROSS SECTIONS AND 2-D PLANVIEWS ALL SHOW STRONG FGEN
FORCING FOR ASCENT ASSOCIATED WITH THE FRONTAL SLOPE BENEATH THE
AFOREMENTIONED JET CORE. FURTHER, A LOT OF THIS LIFT IS IDEALLY
ALIGNED IN THE -12C TO -18C LAYER WHERE HIGH OMEGA CAN BE FOUND
ALONG WITH FGEN. THIS SUPPORTS VERY EFFICIENT FORCING FOR
PERIODS OF HEAVY SNOWFALL AT TIMES, WITH THIS PERIOD OF MAXIMUM
ASCENT BETWEEN APPROXIMATELY 00Z AND 06Z WED (TUESDAY NIGHT).
ADDITIONALLY, MODEL SOUNDINGS REVEAL AN ISOTHERMAL LAYER ALOFT
SUPPORTING THE POTENTIAL FOR LARGE AGGREGATES, ALTHOUGH IF WINDS
ARE TOO STRONG THIS MAY CAUSE LARGE DENDRITES TO BECOME
FRACTURED.
TIMING IS STARTING TO COME INTO BETTER AGREEMENT AS WE APPROACH
THIS EVENT. A LOT OF THE HI RES DATA AND GLOBAL SOLUTIONS SHOW
AN AXIS OF PRECIPITATION DEVELOPING AS EARLY AS TUE MORNING AND
SPREADING EASTWARD GENERALLY ALONG THE OHIO RIVER LIKELY TIED TO
SOME MID LEVEL FGEN. IT WOULD NOT SURPRISE ME TO SEE SOME AREAS
PICK UP A COUPLE OF INCHES FROM THIS. HOWEVER, WE EXPECT THE
MAIN SNOW ACCUMULATIONS TO BEGIN DURING THE LATE AFTERNOON AND
EVENING ACROSS SOUTHEAST MISSOURI AND SOUTHERN ILLINOIS AND THEN
SPREADING EASTWARD INTO THE NIGHT. ENDING TIMES LOOK TO BE
WEDNESDAY MORNING AS SNOW EXITS FROM WEST TO EAST.
THE PREVIOUS COUPLE RUNS OF DETERMINISTIC/ENSEMBLE GUIDANCE
HAVE NOTED A SLIGHT DECREASE IN AMOUNTS, AND A GRADUAL SOUTHERN
SHIFT. HOWEVER, THE NBM AND LREF STILL SHOW A PERSISTENT AXIS OF
HEAVY SNOWFALL FROM SOUTHEAST MISSOURI THROUGH PARTS OF WESTERN
KENTUCKY AND SOUTHERN ILLINOIS. THIS IS LIKELY PICKING UP ON
BANDING POTENTIAL. JUST WHERE THAT BAND SETS UP IS STILL
DIFFICULT TO PINPOINT AND COULD FLUCTUATE BETWEEN NOW AND 6 TO
12 HOURS AHEAD OF THE EVENT. IN THIS BAND OF HEAVY SNOW, AMOUNTS
UP TO TO 8+ INCHES ARE POSSIBLE. OUTSIDE OF THIS BANDING THERE
IS STILL ENOUGH MOISTURE/QPF TO SUPPORT AS MUCH OF 4-8 INCHES OF
SNOW WHICH IS WELL INTO WINTER STORM WARNING CRITERIA AND MORE
THAN ENOUGH TO CAUSE A LOT OF TRAVEL ISSUES. SLR'S WILL LIKELY
END UP AVERAGING AROUND 12:1 TO 15:1 ACROSS SOUTHERN PORTIONS OF
THE AREA TO AS MUCH AS 17:1 TO 20:1 ACROSS THE NORTH.
SO WITH THIS FORECAST ISSUANCE THE MAIN CHANGES WILL BE TO
HEADLINES. HAVE UPGRADED THE WINTER STORM WATCH TO A WINTER
STORM WARNING FOR ALL AREAS EXCEPT THE NORTHERN ROW OF COUNTIES
FROM JEFFERSON, IL EASTWARD THROUGH PIKE, IN. THESE COUNTIES ARE
NOW IN A WINTER WEATHER ADVISORY FOR SNOW AMOUNTS OF 1-3
INCHES. THE TUESDAY AFTERNOON/EVENING AND WEDNESDAY MORNING
COMMUTES LOOK TO BE THE MOST IMPACTED FROM THIS EVENT. AFTER THE
SNOW THE NEXT STORY WILL BE THE PROLONGED PERIOD OF DANGEROUS
COLD TEMPERATURES THROUGH THE REST OF THE WEEK. HIGHS ONLY IN
THE TEENS TO 20'S ARE EXPECTED WEDNESDAY INTO FRIDAY WHILE LOWS
WILL DROP INTO THE SINGLE DIGITS TO 0 (MAYBE BELOW ZERO IN A FEW
LOCATIONS). WIND CHILLS WILL OF COURSE BE EVEN COLDER WITH
VALUES BETWEEN -10 TO -15 ACROSS PORTIONS OF THE AREA. THIS MAY
NECESSITATE THE NEED FOR COLD WEATHER HEADLINES. MODERATING
TEMPERATURES WILL BE SLOW TO COME BY EVEN WITH SOUTHERLY FLOW
BUT TEMPERATURES FINALLY RISE TO ABOVE FREEZING BY THE WEEKEND.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 420 PM CST MON FEB 17 2025
CONDITIONS WILL TRANSITION FROM VFR TO MVFR AS CEILINGS
GRADUALLY LOWER ESPECIALLY AFTER 06 UTC. THERE IS A CHANCE FOR
LIGHT SNOWS TO DEVELOP LATE TONIGHT AND LAST INTO TOMORROW
MORNING. THE HEAVIER SNOW WILL ARRIVE IN THE AFTERNOON, LOWERING
VISIBILITIES, WITH MVFR TO OCCASIONAL IFR CONDITIONS ANTICIPATED
BY THE END OF THE DAY AND INTO THE EVENING HOURS. WINDS WILL
GENERALLY BE FROM THE NORTHEAST 5 TO 15 KTS, WITH SOME GUSTS
OVER 20 KTS POSSIBLE, PRIMARILY LATER TONIGHT AFTER 06 UTC AND
INTO TUESDAY.
PAH WATCHES/WARNINGS/ADVISORIES
IL...WINTER WEATHER ADVISORY FROM NOON TUESDAY TO 9 AM CST
WEDNESDAY FOR ILZ075>078.
WINTER STORM WARNING FROM NOON TUESDAY TO 9 AM CST WEDNESDAY
FOR ILZ080>094.
MO...WINTER STORM WARNING FROM 9 AM TUESDAY TO 9 AM CST WEDNESDAY
FOR MOZ076-086-087-100-107>112-114.
IN...WINTER WEATHER ADVISORY FROM NOON CST /1 PM EST/ TUESDAY TO 9
AM CST /10 AM EST/ WEDNESDAY FOR INZ081-082.
WINTER STORM WARNING FROM NOON TUESDAY TO 9 AM CST WEDNESDAY
FOR INZ085>088.
KY...WINTER STORM WARNING FROM NOON TUESDAY TO 9 AM CST WEDNESDAY
FOR KYZ001>022.
DISCUSSION...AD
AVIATION...CN
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