254
FXUS63 KLMK 090248
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
948 PM EST WED JAN 8 2025
..FORECAST UPDATE
KEY MESSAGES
* BITTERLY COLD TEMPERATURES ARE EXPECTED TONIGHT. A COLD WEATHER
ADVISORY IS IN EFFECT FROM TONIGHT THROUGH THURSDAY MIDMORNING.
* WINTER STORM WATCH REMAINS IN EFFECT FOR ROUGHLY THE SOUTHERN HALF
OF KENTUCKY FOR FRIDAY AND FRIDAY NIGHT.
* FORECAST CONFIDENCE CONTINUES TO INCREASE ON SIGNIFICANT SNOWFALL
FRIDAY AND FRIDAY NIGHT. THE HIGHEST POTENTIAL FOR HEAVY SNOW (4
INCHES OR MORE) ACCUMULATIONS REMAINS ACROSS THE SOUTHERN PART OF
KENTUCKY, MAINLY ALONG AND SOUTH OF THE WESTERN KENTUCKY AND
BLUEGRASS PARKWAYS. NORTH OF THE PARKWAYS, 2-4 INCHES OF SNOW WILL
BE POSSIBLE.
UPDATE
ISSUED AT 948 PM EST WED JAN 8 2025
UPON FURTHER REVIEW, WENT AHEAD WITH A FREEZING FOG ADVISORY ACROSS
THE NORTHERN HALF OR SO OF THE CWA. ALREADY SEEING SOME UPSTREAM OBS
AT 6-7 SM, AND TEMPS HAVE ALREADY GOT DOWN NEAR CROSSOVER T'S WHERE
IT HAS CLEARED OUT. AS A RESULT, EXPECT WE WILL CONTINUE TO COOL.
GUIDANCE CONTINUES TO HIT THE FOG PRETTY HARD, AND WITH MOTORISTS
STARTING TO GET MORE COMFORTABLE WITH STEADILY CLEARING ROADWAYS,
DON'T WANT BLACK ICE TO SURPRISE SOME FOLKS. ONE FINAL CONSIDERATION
IS THAT MID SHIFT WILL HAVE DIFFICULT HEADLINE DECISIONS TO DEAL
WITH FOR THE UPCOMING SNOW, SO WANTED TO GET THIS OFF THEIR PLATE.
STILL MOST CONFIDENT NEAR BODIES OF WATER FOR DENSE FOG/BLACK ICE,
BUT CAN SEE THE WIDESPREAD POTENTIAL AS WELL. DRIVE SAFE EVERYONE.
PREVIOUS UPDATE...
TRICKY FORECAST FOR TONIGHT WITH RESPECT TO FREEZING FOG POTENTIAL.
WENT AHEAD AND ISSUED A SPECIAL WEATHER STATEMENT TO COVER THE
THREAT FOR NOW, BUT WILL BE WATCHING FOR THE NEED FOR AN ADVISORY
OVER THE NEXT FEW HOURS. HERE ARE SOME THOUGHTS ON THE SETUP AND
REASONING:
THIS IS TYPICALLY A CLASSIC SETUP FOR DENSE FOG ACROSS THE NORTHERN
HALF OUR CWA TONIGHT AS WE HAD EXTENSIVE CLOUD COVER TODAY THAT
LIMITED ANY REAL MIXING, AND THIS WAS FOLLOWED BY CLEARING
AROUND/JUST AFTER SUNSET. THE GOOD RADIATIONAL COOLING WITHOUT AND
PREVIOUS AFTERNOON MIXING USUALLY IS A GOOD SETUP, ESPECIALLY AFTER
RAIN. CURRENT MODELS, ESPECIALLY THE HIGHER RES ONES, ARE HITTING
THE DENSE FOG POTENTIAL FAIRLY HARD AT THIS HOUR BUT ALSO SEE A
SCENARIO WHERE THEY MIGHT BE OVERDONE. HOW MUCH OF THE SNOW PACK CAN
BE A MOISTURE SOURCE WHEN IT IS FROZEN? DON'T HAVE A LOT OF CASES I
CAN REMEMBER IN MY 18 YEARS OF FORECASTING SO I'M ACTUALLY PRETTY
CURIOUS TO SEE HOW THIS PLAYS OUT. DO FEEL MORE CONFIDENT THAT SOME
AREAS NEAR WATER BODIES WILL SEE FREEZING FOG POTENTIAL, SO PLEASE
USE CAUTION IF TRAVELING, ESPECIALLY ONCE FOG IS ENCOUNTERED. BLACK
ICE AFTER A COUPLE OF DAYS OF STEADY ROAD IMPROVEMENT COULD CAUSE
SOME ISSUES. WE'LL BE WATCHING CLOSELY FOR A POTENTIAL UPGRADE. FOR
NOW, WILL ADD A BIT MORE MENTION TO THE GRIDS/FORECAST. STAY TUNED.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 355 PM EST WED JAN 8 2025
SYNOPSIS...MID-LEVEL SHORTWAVE TROUGH RESPONSIBLE FOR SCATTERED
SNOW SHOWERS TODAY WILL EJECT EASTWARD WHILE WEAK RIDGING MOVES FROM
THE MIDWEST TO THE GREAT LAKES. AT THE SURFACE, ARCTIC HIGH PRESSURE
QUICKLY TRANSITIONS ALONG THE LOWER OHIO VALLEY, BRINGING DRY
WEATHER AND BITTERLY COLD TEMPERATURES TO THE REGION.
MODEL EVALUATION/CONFIDENCE...GREATEST CHALLENGE DURING THE SHORT
TERM WILL BE HOW LOW TEMPERATURES DROP TONIGHT. COMPARED TO PREVIOUS
DAYS, MODELS HAVE GONE UP BY A FEW DEGREES WHICH CAN BE ATTRIBUTED
TO THE CLOUD COVER MANY OF THEM FEATURE OVERNIGHT. THAT BEING SAID,
THE EARLY AFTERNOON VISIBLE SATELLITE IS SHOWING THE MID-LEVEL CLOUD
DECK, ASSOCIATED WITH THE MID-LEVEL WAVE, MOVING TO THE SOUTH AND
EAST PRETTY QUICKLY. THE REMAINING LOW-LEVEL CLOUDS BEHIND THE MID-
LEVEL CLOUD DECK ARE DIURNALLY DRIVEN AND SHOULD DISSIPATE LATER
THIS AFTERNOON AND EARLY EVENING. AS A RESULT, THERE IS INCREASING
CONFIDENCE IN CLEARING SKIES, ESPECIALLY ALONG I-64, WHERE
TEMPERATURES ARE EXPECTED TO FALL NEAR OR BELOW ZERO.
THIS AFTERNOON...EARLIER SCATTERED, LIGHT SNOW SHOWER ACTIVITY HAVE
DECREASED IN COVERAGE AND INTENSITY AND WILL CONTINUE TO DO SO THE
REST OF THIS AFTERNOON. OVERALL, AROUND AN INCH OF SNOW HAS FALLEN
IN ISOLATED LOCATIONS WITH LESSER WIDESPREAD AMOUNTS. ON THE OTHER
HAND, DAYTIME RGB SATELLITE REVEALS LOW-LEVEL CLOUDS FILLING IN
BEHIND THE MID-LEVEL CLOUD DECK DRIVEN BY DIURNAL HEATING AND
PARTIALLY-MELTED SNOWFALL. THEREFORE, THESE LOW-LEVEL CLOUDS SHOULD
DISSIPATE AROUND OR SHORTLY AFTER SUNSET LEADING TO MOSTLY CLEAR
SKIES OVERNIGHT.
TONIGHT...BASED ON CLEARING SKIES, STRONG SUBSIDENCE ACCOMPANYING
THE ARCTIC SURFACE HIGH, AND COOLING EFFECT FROM ONGOING SNOWPACK,
WENT AHEAD AND ISSUE A COLD WEATHER ADVISORY FOR COUNTIES ROUGHLY
ALONG AND NORTH OF I-64. NOT ONLY MINIMUM APPARENT TEMPERATURES WERE
CONSIDERED TO ISSUE THIS HEADLINE, BUT ALSO IMPACTS ON FOLKS WHO ARE
ARE STILL EXPERIENCING POWER OUTAGES. TEMPERATURE WISE, LOWS WILL
RANGE FROM NEAR TO SLIGHTLY BELOW ZERO VALUES IN SOUTHERN INDIANA
AND NORTHERN KENTUCKY TO LOW TEENS IN SOUTH CENTRAL KENTUCKY. ASIDE
FROM THE BITTERLY COLD TEMPERATURES, THERE IS A LOW CHANCE OF
ISOLATED AND SHALLOW FREEZING FOG ALONG RIVERS AND AREAS THAT HAVE
LOST THE SNOW COVER WHERE MOISTURE WILL BE READILY AVAILABLE.
THURSDAY...EXPECT A LOW TEMPERATURE RECOVERY DURING THE MORNING WITH
SINGLE-DIGIT VALUES IN THE NORTHERN HALF OF THE FORECAST AREA
LINGERING CLOSE TO LUNCH TIME. DRY WEATHER AND LIGHT WINDS WILL
PREDOMINATE WITH DIRECT SOLAR RADIATION STARTING TO SUBSTANTIALLY
MELT THE SNOWPACK.
LONG TERM /THURSDAY THROUGH WEDNESDAY/
ISSUED AT 355 PM EST WED JAN 8 2025
==============================================================
* SIGNIFICANT SNOWFALL EXPECTED FRIDAY AND FRIDAY NIGHT
* WINTER STORM WATCH REMAINS IN EFFECT FOR THE SOUTHERN HALF OF
KENTUCKY
==============================================================
THURSDAY NIGHT...
THURSDAY NIGHT IS THE CALM BEFORE THE NEXT STORM. CONDITIONS WILL BE
DRY AND COLD WITH BRIEF RIDGING IN PLACE. HIGH PRESSURE SLIDES OFF
TO THE EAST, AND MID/HIGH CLOUDS QUICKLY INCREASE IN COVERAGE FROM
THE WSW. LOWS WILL OCCUR EARLIER IN THE NIGHT THAN USUAL, WITH
READINGS IN THE 10-20 DEGREE RANGE. HOWEVER, A COUPLE OF OUR TYPICAL
COOL SPOTS IN THE NORTHERN BLUEGRASS COULD DIP INTO THE SINGLE
DIGITS. TO THE SW, TEMPS COULD STABILIZE IN THE LOW/MID 20S DUE TO
INCREASING CLOUD COVER.
FRIDAY THROUGH SATURDAY...
BOTTOM LINE UP FRONT: CONFIDENCE REMAINS HIGH IN IMPACTFUL
ACCUMULATING SNOWS FRIDAY INTO SATURDAY MORNING. IN GENERAL, A
WIDESPREAD AND RELATIVELY UNIFORM 2-5 INCHES OF SNOW ACCUMULATION IS
ANTICIPATED FRIDAY MORNING THROUGH SATURDAY MORNING. THE HIGHER SNOW
AMOUNTS (4-5+ INCHES) IN THAT RANGE ARE MOST LIKELY ACROSS SOUTH-
CENTRAL KENTUCKY, WITH SOMEWHAT LOWER (2-4 INCHES) SNOW AMOUNTS
ACROSS SOUTHERN INDIANA AND NORTH-CENTRAL KENTUCKY. IT IS WORTH
NOTING LOCALIZED SNOW TOTALS APPROACHING 6 INCHES WILL BE POSSIBLE
ACROSS SOUTH-CENTRAL KY.
CONFIDENCE IS HIGH IN WIDESPREAD MINOR TO MODERATE IMPACTS DUE TO
SNOW FRIDAY INTO SATURDAY. EXPECT SLICK AND SNOW-COVERED ROADS, MOST
NOTABLY IMPACTING THE FRIDAY EVENING COMMUTE. PLAN FOR HAZARDOUS,
SLOW TRAVEL CONDITIONS FRIDAY AFTERNOON THROUGH FRIDAY NIGHT.
FORECAST CONFIDENCE ALSO REMAINS HIGH IN SNOW AS THE SOLE
PRECIPITATION TYPE.
METEOROLOGICAL DISCUSSION: A FULL-LATITUDE UPPER LEVEL TROUGH WILL
TRANSLATE EASTWARD OVER THE UPPER MIDWEST AND PLAINS ON FRIDAY, WITH
A SHARPENING MID-LEVEL WAVE OVER THE SOUTHERN PLAINS AND OZARKS. AT
THE SURFACE, LOW PRESSURE IS FORECAST TO GRADUALLY DEEPEN AS IT
GENERALLY MOVES EAST ALONG THE GULF COAST.
MID-LEVEL ASCENT WILL BEGIN INCREASING FRIDAY MORNING AHEAD OF THE
APPROACHING TROUGH, BUT PLENTY OF LOW-LEVEL DRY AIR WILL LIMIT
SNOWFALL CHANCES PRIOR TO DAYBREAK. AFTER 12Z, EXPECT SNOW CHANCES
TO INCREASE FROM WEST TO EAST. MODERATE MID-LEVEL FRONTOGENETICAL
ASCENT PEAKS IN INTENSITY FRIDAY AFTERNOON AND EVENING, AND SNOWFALL
COVERAGE AND INTENSITY WILL BE AT ITS PEAK DURING THIS TIME (18Z FRI
- 06Z SAT). QPF HAS NOT CHANGED DRASTICALLY WITH THIS FORECAST
CYCLE. AROUND 0.20-0.40 INCHES (SWE) IS FORECAST, WITH THE HIGHEST
AMOUNTS ACROSS SOUTH-CENTRAL KY. BASED ON A DEEP COLD LAYER, AND
GOOD SATURATION/LIFT WITHIN THE -10 TO -20 C LAYER, SNOWFALL RATIOS
ARE EXPECTED TO AVERAGE BETWEEN 12:1 AND 15:1.
LIGHT TO MODERATE SNOWFALL WILL CONTINUE FRIDAY NIGHT, WITH LIGHT
SNOW TAPERING OFF SATURDAY MORNING. TOTAL SNOWFALL AMOUNTS ARE
LIKELY TO BE BETWEEN 2-4 INCHES ACROSS SOUTHERN INDIANA AND NORTH-
CENTRAL KY. SNOWFALL AMOUNTS OF 3-6 INCHES WILL BE POSSIBLE ACROSS
SOUTH-CENTRAL KENTUCKY. AS FOR THESE SNOWFALL AMOUNTS, FORECAST
CONFIDENCE REMAINS MEDIUM. THE ONE X-FACTOR WILL BE THE POTENTIAL
FOR MESOSCALE BANDED PRECIP, BUT CONFIDENCE REMAINS LOW ON THE
DEVELOPMENT AND PLACEMENT OF ANY ENHANCED SNOWFALL BANDS. BECAUSE
MESOSCALE DETAILS WILL REQUIRE MORE TIME TO FLESH OUT, WILL HOLD OFF
OF ANY CHANGES TO THE WINTER STORM WATCH AT THIS TIME. SOME
LINGERING SPREAD IN SUPER ENSEMBLE DATA/PLUMES SUGGESTS WE CANNOT
RULE OUT ADDING ADDITIONAL COUNTIES TO THE WATCH OR A POSSIBLE
FUTURE WINTER STORM WARNING. ON THE FLIP SIDE, WE CAN ALSO NOT RULE
OUT A POSSIBLE FUTURE WINTER WEATHER ADVISORY FOR SOME AREAS
CURRENTLY INCLUDED IN THE WINTER STORM WATCH. IN SHORT, STILL LIKE
THE OVERALL PLACEMENT OF THE WINTER STORM WATCH.
TEMPERATURES FRIDAY AFTERNOON WILL CREEP UP TO AROUND THE FREEZING
MARK, BEFORE FALLING BACK INTO THE 20S FRIDAY NIGHT. CLOUDS SHOULD
LINGER THROUGH MOST OF SATURDAY, AND TEMPERATURES DO NOT APPEAR
LIKELY TO RISE ABOVE FREEZING. EXPECT HIGHS IN THE UPPER 20S TO
LOWER 30S.
SATURDAY NIGHT - TUESDAY...
THE SECOND HALF OF THE WEEKEND LOOKS QUIET WITH HIGH PRESSURE
BUILDING ACROSS THE REGION. DEPENDING ON CLOUD COVER, TEMPS WILL
LIKELY DROP INTO THE TEENS SATURDAY NIGHT AND SUNDAY MORNING.
TEMPERATURES WILL RECOVER NICELY ON SUNDAY, HOWEVER, THANKS TO A WAA
REGIME WITH DEVELOPING SOUTHERLY FLOW BEHIND THE DEPARTING AREA OF
HIGH PRESSURE. AFTERNOON HIGHS LOOK TO REACH THE MID 30S IN MOST
AREAS.
THE NEXT WAVE OF LOW PRESSURE SLIDES ACROSS THE GREAT LAKES SUNDAY
NIGHT INTO MONDAY. MOISTURE LOOKS LIMITED AT THIS TIME, WITH BETTER
SNOW POTENTIAL WELL TO OUR NORTH. HOWEVER, THERE IS A SLIGHT CHANCE
FOR BRIEF LIGHT SNOW OR FLURRIES. ANOTHER SHOT OF COLD AIR IS LIKELY
BEHIND THIS WAVE FOR MONDAY NIGHT INTO MIDWEEK.
AVIATION /00Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 718 PM EST WED JAN 8 2025
STRATOCU LAYER STARTING TO PUSH SOUTH OF THE OHIO RIVER, SO DO
EXPECT SDF/LEX/RGA TO EVENTUALLY GO CLEAR. BWG WILL BE A BIT LATER
TONIGHT, LIKELY AROUND MIDNIGHT OR SO. LOOK FOR LIGHT AND VARIABLE
WINDS WITH MOSTLY CLEAR SKIES FOR MUCH OF THE NIGHT. THE BIG CONCERN
FOR THE PRE-DAWN AND MORNING HOURS WILL BE WHETHER SOME DENSE
FREEZING FOG FORMS. LOOKS LIKE A GOOD SETUP FOR IT GIVEN LATER
CLEARING FOLLOWED BY GOOD RADIATIONAL COOLING OVERNIGHT. HI-RES
GUIDANCE IS STARTING TO HIT IT PRETTY HARD, SO WENT AHEAD WITH SOME
PESSIMISTIC OVERNIGHT/MORNING CONDITIONS AT THE I-64 CORRIDOR TAF
SITES (HNB/SDF/LEX/RGA).
LMK WATCHES/WARNINGS/ADVISORIES
KY...COLD WEATHER ADVISORY UNTIL 10 AM EST /9 AM CST/ THURSDAY FOR
KYZ023-025-030>037-040>043-049.
FREEZING FOG ADVISORY UNTIL 10 AM EST /9 AM CST/ THURSDAY FOR
KYZ023>043-045>049-053>057.
WINTER STORM WATCH FROM LATE THURSDAY NIGHT THROUGH SATURDAY
MORNING FOR KYZ026>028-045>048-053>057-061>067-070>078-
081-082.
IN...COLD WEATHER ADVISORY UNTIL 10 AM EST /9 AM CST/ THURSDAY FOR
INZ076>079-083-084-089>092.
FREEZING FOG ADVISORY UNTIL 10 AM EST /9 AM CST/ THURSDAY FOR
INZ076>079-083-084-089>092.
UPDATE...BJS
SHORT TERM...ALL
LONG TERM...EBW
AVIATION...BJS
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