530
FXUS63 KLMK 092352
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
652 PM EST THU JAN 9 2025
..UPDATED AVIATION DISCUSSION
KEY MESSAGES
* A SIGNIFICANT WINTER STORM WILL AFFECT THE REGION FRIDAY AND
FRIDAY NIGHT. WIDESPREAD SNOWFALL ACCUMULATIONS OF 3-6 INCHES
WITH LOCALLY HIGHER AMOUNTS ARE EXPECTED.
* A WINTER STORM WARNING REMAINS IN EFFECT FOR ALL OF CENTRAL
KENTUCKY AND SOUTHERN INDIANA.
SHORT TERM /THROUGH FRIDAY NIGHT/
ISSUED AT 345 PM EST THU JAN 9 2025
SYNOPSIS...WEAK MID-LEVEL RIDGING EXTENDING ALONG THE GREAT LAKES
AND OHIO VALLEY WILL LIFT TOWARDS THE NORTHEAST US AS A HIGHLY-
AMPLIFIED LONGWAVE TROUGH APPROACHES FROM THE WEST. NORTHERN-STREAM
SHORTWAVE EMBEDDED IN THE BROADER CIRCULATION WILL OUTPACE THE
SOUTHERN-STREAM ENERGY ALLOWING THE UPPER JET TO STRETCH FROM TEXAS
ALL THE WAY TO KENTUCKY ON FRIDAY. AT THE LOWER LEVELS, HIGH
PRESSURE WILL SLOWLY TRANSITION ACROSS THE FORECAST AREA TODAY AND
TONIGHT WHILE CYCLOGENESIS TAKES PLACE OVER THE NW GULF COAST. THE
AFOREMENTIONED SURFACE LOW WILL EVENTUALLY TRACK ACROSS THE GULF
COAST TOMORROW AT THE SAME TIME A COLD FRONT APPROACHES FROM THE MID
MISSISSIPPI VALLEY. THE COMBINATION OF ONGOING BELOW-FREEZING
TEMPERATURES AND INCREASING PRECIPITATION WILL BRING A PERIOD OF
MODERATE TO LOCALLY HEAVY SNOWFALL TO THE REGION.
MODEL EVALUATION/CONFIDENCE...OVERALL, CONFIDENCE IN SNOWFALL
AMOUNTS AND TIMING OF PRECIPITATION HAVE SLIGHTLY INCREASED WITH
RESPECT TO THE PREVIOUS FORECAST PACKAGE. DETERMINISTIC AND ENSEMBLE
MODEL GUIDANCE STILL SUPPORT WIDESPREAD ACCUMULATIONS IN THE 3-5"
WITH TWO DISTINCTIVE LOCATIONS FOR 4+" OF ACCUMULATED SNOW. THE
FIRST LOCATION IS SOUTHERN KENTUCKY WHICH HAS BEEN WELL-ADVERTISED
DURING THE PAST 24-36 HOURS. THE SECOND ONE IS ALONG SOUTHWEST IN
AND WEST CENTRAL KY WHERE GLOBAL MODELS HAVE BEEN INDICATING
INCREASING CHANCES OF HEAVIER SNOWFALL (4+ INCHES). THE LATTER IS
PROBABLY RELATED TO MESOSCALE/SYNOPTIC FORCING AHEAD OF THE
APPROACHING COLD FRONT AND STREAMING UPPER JET. IN ADDITION, HI-RES
MODELS HAVE BEEN INDICATING EVEN HIGHER CHANCES 4+ INCHES OF SNOW
WITH AUGMENTING PROBABILITIES OF 6+ INCHES. SPECIFICALLY, HREF MEAN
AND PMM 24-HR SNOWFALL SIGNALS TO SNOWFALL AMOUNTS GOING UP TO 6
INCHES ALONG SOUTHERN KENTUCKY WITH THE 4-INCH SIGNATURE COVERING A
WIDER PORTION OF THE WESTERN HALF OF THE FORECAST AREA. THIS COULD
INDICATE THAT THE HI-RES DATA MIGHT BE CAPTURING SOME MESO
ENHANCEMENT ALONG THE STRONGEST SOURCES OF LIFTING.
TONIGHT...DRY AND COLD CONDITIONS WILL CONTINUE THIS AFTERNOON INTO
THIS EVENING AS THE HIGH PRESSURE CENTER LINGERS OVERHEAD. FOR
TONIGHT, PROGRESSIVE TOP-DOWN MOISTENING WILL TAKE PLACE AS
ISENTROPIC LIFTING AND RESULTANT MOISTURE ADVECTION OVERSPREAD THE
LOWER OHIO VALLEY FROM THE SOUTH. AS A RESULT, EXPECT BROKEN TO
OVERCAST CONDITIONS WITH HIGH- TO MID-LEVEL CLOUDS EXPANDING
NORTHEAST. GFS SOUNDINGS DEPICT SATURATION AND DECENT LAPSE RATES IN
THE DGZ TO ACCOUNT FOR SNOW FLURRIES BEFORE SUNRISE, EVEN THOUGH THE
LOW LEVELS WILL STILL BE FAIRLY DRY SO MOST OF THE PRECIPITATION
MIGHT SUBLIMATE.
FRIDAY - FRIDAY NIGHT...PRECIPITATION RATE WILL GRADUALLY INTENSIFY
AS THE COLUMN SATURATES GIVEN MOISTURE ADVECTION AND FORCING
MECHANISMS (COLD FRONT AND SURFACE LOW) APPROACH THE REGION.
TEMPERATURES WILL REMAIN BELOW-FREEZING DURING THE WHOLE EVENT, SO
SNOW IS THE ONLY PRECIPITATION TYPE THIS TIME AROUND. LIGHT SNOW
SHOWERS WILL INCREASE IN COVERAGE DURING THE MORNING WITH MEASURABLE
AMOUNTS PROBABLY BY MIDMORNING OR SO. TIMING FOR HEAVIER SNOW RATES
(MOSTLY BELOW 1"/HR) REMAINS FRIDAY AFTERNOON INTO THE EVENING;
HOWEVER, BRIEF PERIODS OF ENHANCED RATES (~1"/HR) ARE POSSIBLE ALONG
SOUTH-CENTRAL KENTUCKY SINCE IT WILL BE CLOSER TO THE DEFORMATION
ZONE ASSOCIATED WITH THE SURFACE LOW TRACKING ALONG THE GULF COAST.
COMPARED TO THE PREVIOUS FORECAST, THE SNOWFALL AMOUNTS OVER SW IN
AND WEST CENTRAL KENTUCKY HAVE GONE UP BY APPROX. 0.5-1.5 INCHES. AS
EXPLAINED ABOVE, THIS CHANGE WAS DRIVEN BY HI-RES GUIDANCE AND COULD
BE EXPLAINED BY THE COMBINATION OF MESOSCALE LIFTING AHEAD OF THE
COLD FRONT, SYNOPTIC LIFTING IN THE LEFT EXIT REGION OF THE 250-MB
JET, ANOMALOUS MOISTURE ADVECTION, AND THE EXPECT SLR (10 TO 15).
THESE FACTORS WILL STEEPEN DGZ LAPSE RATES WHILE KEEPING IT
SATURATED FOR A PROLONGED PERIOD OF TIME, POTENTIALLY YIELDING
SCATTERED REPORTS OF 4 OR MORE INCHES OF SNOW. THE 24-HR SNOWFALL
ACCUMULATION FOLLOW A BIMODAL DISTRIBUTION WITH MAXIMA IN SOUTH-
CENTRAL KY AND SW IN/WEST CENTRAL IN, WITH THE LOCAL MINIMUM (LOWEST
CONFIDENCE IN 4+ INCHES OF SNOW) TOWARDS THE BLUEGRASS AND EAST
CENTRAL KENTUCKY. SNOW COVERAGE AND INTENSITY WILL DECREASE AROUND
MIDNIGHT WITH ONLY LIGHT SNOW OR FLURRIES LINGERING TOWARDS SUNRISE
ON SATURDAY.
LONG TERM /SATURDAY THROUGH THURSDAY/
ISSUED AT 345 PM EST THU JAN 9 2025
SATURDAY THROUGH MONDAY...
HIGH PRESSURE BUILDS INTO THE REGION ON SATURDAY BEHIND THE
DEPARTING STORM. IT WILL BE A COLD DAY WITH THE FRESH SNOWPACK AND
STEADY NW WIND. WIND CHILLS WILL REMAIN IN THE TEENS AND 20S, AND
LOW-LEVEL CLOUDS WILL LINGER THROUGHOUT THE DAY. AIR TEMPERATURES
WILL MAX OUT IN THE UPPER 20S TO LOWER 30S SATURDAY AFTERNOON.
SATURDAY NIGHT LOOKS PARTLY CLOUDY AND COLD, WITH LOWS IN THE TEENS.
HOW FAR THE TEMPERATURE DROPS WILL DEPEND ON THE EVOLUTION OF THE
STRATUS, AND HOW QUICKLY THE CLOUDS SCATTER OUT.
SFC HIGH PRESSURE SLIPS OFF TO THE EAST ON SUNDAY, ALLOWING THE
DEVELOPMENT OF SW FLOW WAA. SKIES SHOULD RANGE FROM PARTLY TO MOSTLY
SUNNY, WITH AFTERNOON HIGHS IN THE MID 30S. THIS WILL BEGIN MELTING
THE SNOWPACK. CLOUDS INCREASE SUNDAY NIGHT AHEAD OF AN APPROACHING
UPPER LEVEL SHORTWAVE TROUGH AND SFC COLD FRONT. THE FRONT APPEARS
LIKELY TO MOVE THROUGH SOMETIME ON MONDAY. THIS FRONT WILL BE
MOISTURE-STARVED, BUT THERE IS A SMALL CHANCE/WINDOW FOR LIGHT SNOW
OR FLURRIES MONDAY MORNING.
MONDAY NIGHT THROUGH WEDNESDAY...
SOME VERY COLD AIR WILL MOVE INTO THE REGION MONDAY NIGHT INTO
MIDWEEK BEHIND MONDAY'S COLD FRONT. A REINFORCING SHOT OF COLDER AIR
ARRIVES IN THE TUE-WED TIME FRAME. HIGHS ONLY IN THE 20S WILL BE
POSSIBLE THESE DAYS, WITH NIGHTTIME LOWS IN THE SINGLE DIGITS OR
TEENS. THERE COULD BE ANOTHER OPPORTUNITY FOR LIGHT SNOW SOMETIME IN
THE MIDWEEK TIME FRAME, AS ANY WEAK DISTURBANCES ALOFT TAKE
ADVANTAGE OF THE VERY COLD TEMPS IN THE LOWER LEVELS.
AVIATION /00Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 650 PM EST THU JAN 9 2025
VFR CONDITIONS WILL CONTINUE OVERNIGHT, BUT AS A COLD FRONT
APPROACHES TOMORROW MORNING, SNOW WILL BEGIN TO WORK WEST TO EAST
ACROSS SOUTHERN INDIANA AND CENTRAL KENTUCKY. THIS WILL DROP
CEILINGS AND REDUCE VISIBILITIES. EVERYTHING SHOULD FALL AS SNOW
WITH NO P-TYPE ISSUES. IMPROVEMENTS IN CEILINGS AND VISIBILITIES CAN
BE EXPECTED LATE FRIDAY NIGHT AND SATURDAY MORNING.
LMK WATCHES/WARNINGS/ADVISORIES
KY...WINTER STORM WARNING FROM 4 AM EST /3 AM CST/ FRIDAY TO 7 AM
EST /6 AM CST/ SATURDAY FOR KYZ023>043-045>049-053>057-
061>067-070>078-081-082.
IN...WINTER STORM WARNING FROM 4 AM EST /3 AM CST/ FRIDAY TO 7 AM
EST /6 AM CST/ SATURDAY FOR INZ076>079-083-084-089>092.
SHORT TERM...ALL
LONG TERM...EBW
AVIATION...KDW
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page