418
FXUS63 KJKL 181006
AFDJKL
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
506 AM EST SAT JAN 18 2025
KEY MESSAGES
- RAIN TODAY WILL CHANGE OVER TO SNOW FROM NORTHWEST TO SOUTHEAST
LATE THIS AFTERNOON THROUGH TONIGHT.
- ACCUMULATING SNOW IS FORECAST FROM SATURDAY NIGHT INTO SUNDAY
NIGHT.
- APPARENT TEMPERATURES ARE FORECAST NEAR OR BELOW ZERO FOR MUCH
OF THE AREA ON MONDAY, TUESDAY, AND WEDNESDAY OF NEXT WEEK.
SHORT TERM
(THIS MORNING THROUGH SUNDAY NIGHT)
ISSUED AT 500 AM EST FRI JAN 17 2025
AN INTRICATE ACCUMULATING SNOWFALL EVENT IS BECOMING INCREASINGLY
LIKELY TONIGHT THROUGH SUNDAY NIGHT TIMEFRAME. AFTER RAIN
TRANSITIONS TO SNOW BEHIND THE ARCTIC FRONT TONIGHT, A BAROCLINIC
LEAF (POSSIBLY WITH EMBEDDED FRONTOGENETIC BANDING RISING THROUGH
A LOW EPV ENVIRONMENT ATOP FORCING ROOTED NEAR 700MB) WILL PASS
OVER EASTERN KENTUCKY SUNDAY MORNING/EARLY AFTERNOON WITH
WIDESPREAD LIGHT TO POSSIBLY MODERATE SNOWFALL. THE SNOW WILL
INITIALLY BE RELATIVELY WET AND DENSE BUT SHOULD QUICKLY BECOME
LIGHT AND FLUFFY WITH RISING SLRS AS THE COLUMN COOLS AND SURFACE
TEMPERATURES FALL INTO/THROUGH THE 20S. BELOW THE
SYNOPTIC/MESOSCALE SNOW GENERATION MECHANISMS ALOFT, NORTHWESTERLY
FLOW IN THE SHALLOW SURFACE-850 MB MOIST COLD LAYER BEHIND THE
ARCTIC FRONT WILL FAVOR ENHANCED UPSLOPE LIFTING, ESPECIALLY ALONG
AND NEAR PINE/BLACK/LOG/CUMBERLAND MOUNTAINS.
AS TEMPERATURES GROW COLDER, THE CAMS/NAM12/RAP13 ARE PICKING UP
ON THE POTENTIAL FOR LAKE-ENHANCED SNOW STREAMERS TO DEVELOP OFF
OF LAKE MICHIGAN IN AN INITIALLY NORTHERLY FLOW BEFORE EFFECTIVELY
COALESCING INTO AN INTENSIFYING SECONDARY ARCTIC COLD FRONT
(EVIDENT IN THE SURFACE-925MB FRONTOGENESIS FIELDS) THAT SWEEPS
EASTWARD ACROSS THE CWA LATE SUNDAY AFTERNOON AND EVENING. MODEL
SOUNDINGS SHOW PEAK OMEGA VALUES BECOMING NEAR IDEALLY CENTERED
WITHIN THE DENDRITIC GROWTH ZONE AMIDST A STEEP LOW-LEVEL LAPSE
RATE ENVIRONMENT EXTENDING TO -20C OR POSSIBLY A BIT HIGHER. THIS
KIND OF PROFILE IS SUPPORTIVE OF INTENSE SNOWFALL RATES OVER A
BRIEF PERIOD OF TIME. IN FACT, A QUICK 1 TO 2+ INCHES OF SNOWFALL
IN LESS THAN AN HOUR IS CONCEIVABLE, ESPECIALLY WHERE THE LAKE-
ENHANCED BAND ENCOUNTERS UPSLOPE LIFTING NEAR/OVER THE ESCARPMENT
AND PINE/BLACK/LOG/CUMBERLAND MOUNTAINS. IF THIS LAKE-EFFECT
SNOWBAND MATERIALIZES, ITS EASTWARD PROGRESS WILL BE RAPID, THUS
LIMITING EXCESSIVE SNOWFALL AMOUNTS AT A GIVEN LOCATION.
IN ADDITION TO HIGH SNOWFALL RATES AND TEMPERATURES DROPPING
QUICKLY IN THE THE TEENS OR COLDER BEHIND THE BAND, WINDS ALONG
AND BEHIND THE BAND WILL BECOME GUSTY. BUFKIT MIXED-LAYER MOMENTUM
TRANSFER IS SUPPORTIVE OF WIND GUSTS IN THE 20 TO 30 MPH RANGE
WHICH COULD LEAD TO VERY LOW VISIBILITY, ESPECIALLY DURING THE
PASSAGE OF THE POSSIBLE SECONDARY FRONT. THE HRRR DEPICTS
VISIBILITIES AS LOW AS 0.1-MILE. THE QUICKLY DROPPING TEMPERATURES
COULD CAUSE LINGERING LIQUID WATER TO FREEZE AS ROAD TREATMENTS
LOOSE EFFICACY IN THE RAPIDLY COOLING AIR MASS. ADDITIONALLY, THE
STRONG, GUSTY WINDS WILL HELP DRIFT THE DRY, FLUFFY SNOWFALL ONTO
ROADWAYS IN OPEN AREAS AND OVER RIDGES.
FORECASTER CONFIDENCE IN REACHING THE 4" THRESHOLD FOR A WINTER
STORM WARNING OVER PORTIONS OF THE AREA WAS TOO LOW FOR ISSUANCE
DUE TO MESOSCALE EFFECTS AND MODEL VARIABILITY IN THE STRENGTH OF
THE SYNOPTIC SNOWFALL. WINTER WEATHER ADVISORIES WERE ISSUED FOR
THE ENTIRE FORECAST AREA WITH THIS MORNING'S FORECAST PACKAGE, BUT
A TARGETED WINTER STORM WARNING MAY ALSO BE WARRANTED AS
MESOSCALE EVOLUTION BECOMES MORE CERTAIN. IF A WINTER STORM
WARNING IS ISSUED, NWS DIRECTIVE PROHIBITS THE ISSUANCE OF SNOW
SQUALL WARNINGS IN THE SAME FORECAST ZONES THROUGH THE DURATION OF
THE WINTER STORM WARNING.
LONG TERM
(MONDAY MORNING THROUGH FRIDAY)
ISSUED AT 430 AM EST SAT JAN 18 2025
BY MONDAY MORNING NEXT WEEK, MODELS ARE IN GOOD CONSENSUS OVER A
LONG WAVE TROUGH COVERING MUCH OF CONUS WITH A SHOT OF ARCTIC
AIR. FOR EASTERN KENTUCKY, THESE EFFECTS WILL BE FELT AS EARLY AS
MONDAY MORNING, WHERE MORNING TEMPERATURES WILL BE IN THE SINGLE
DIGITS ACROSS THE AREA. HIGH TEMPERATURES FOR THE DAY AREN'T
EXPECTED TO MAKE IT OUT OF THE TEENS. THIS IS 25 TO 30 DEGREES
BELOW CLIMATOLOGICAL NORMALS FOR THIS TIME OF YEAR. WINDS WILL BE
OUT OF THE WEST TO NORTHWEST 5 TO 10 MPH WITH GUSTS TO 15 MPH,
OTHERWISE DRY WEATHER IS EXPECTED. DURING THE DAY MONDAY, A 500-DM
EMBEDDED SHORTWAVE WILL DIG SOUTH OUT OF MANITOBA. THIS WILL HELP
IN PATTERN PROGRESSION. MONDAY NIGHT LOWS WILL BE IN THE SINGLE
DIGITS FOR THE 2ND NIGHT IN A ROW. CLIMATOLOGICAL NORMAL LOWS FOR
THIS TIME OF YEAR ARE IN THE UPPER 20S.
TUESDAY, A TROUGH AXIS FROM THE EMBEDDED MANITOBA SHORTWAVE WILL MOVE
THROUGH THE STATE, WITH SNOW SHOWERS LIKELY PASSING SOUTH AND EAST
OF THE AREA. SOME FLURRIES MAY BE POSSIBLE DURING THE AFTERNOON AND
EVENING. 500-MB HEIGHT RISES ALONG WITH SOUTHWESTERLY WINDS WILL AID
IN HIGH TEMPERATURES REACHING INTO THE LOW TO MID 20S. HOWEVER,
WINDS VEER TO NORTHWESTERLY AND EVENTUALLY NORTHEASTERLY DIRECTION
OVERNIGHT, BRINGING COLDER AIR BACK INTO THE AREA. LOWS TUESDAY
NIGHT ARE EXPECTED TO REMAIN IN THE SINGLE DIGITS FOR A 3RD NIGHT IN
A ROW, WITH AREAS ALONG AND NORTH OF THE I-64 CORRIDOR BEING AT OR
BELOW ZERO.
WEDNESDAY AND THURSDAY 500-MB HEIGHTS WILL RISE IN LIEU OF THE
EXITING SYSTEM FROM TUESDAY. QUIET WEATHER IS EXPECTED EACH DAY,
WITH HIGHS WEDNESDAY IN THE LOW TO MID 20S, RISING INTO THE MID TO
UPPER 30S THURSDAY. LOWS WEDNESDAY NIGHT FINALLY WARM OUT OF THE
SINGLE DIGITS, AND TEENS WILL BE WELCOMED. THURSDAY NIGHT IS
EXPECTED TO BE SLIGHTLY WARMER. WHILE THIS QUIET WEATHER IS
OCCURRING ACROSS EASTERN KENTUCKY ON WEDNESDAY, ANOTHER UPPER-
LEVEL LOW SPILLS OVER THE HIGH-AMPLITUDE RIDGE OUT OVER WESTERN
CANADA AND CONUS, ENTERING THE MONTANA AREA IN THE MORNING. THIS
MAY LEAD TO SPRINKLES AND FLURRIES FRIDAY AND SATURDAY.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1219 AM EST SAT JAN 18 2025
VFR CONDITIONS WERE PRESENT AT THE START OF THE PERIOD. MID- TO
HIGH-LEVEL CLOUDS ARE STREAMING IN FROM THE WEST AND WILL LOWER
TO MVFR AND IFR CEILINGS AS RAIN DEVELOPS FROM WEST TO EAST LATE
TONIGHT. THE MVFR/IFR CONDITIONS AND RAIN AT TIMES WILL THEN
PERSIST THROUGH THE DAY SATURDAY, WITH IFR AND LOWER CONDITIONS
PERSISTING INTO SATURDAY NIGHT. THE RAIN IS EXPECTED TO BEGIN
TRANSITIONING OVER TO SNOW IN THE I-64 CORRIDOR AFTER SUNSET
SATURDAY, WITH THE CHANGEOVER MOVING SOUTHEAST WITH TIME THROUGH
THE REMAINDER OF THE TAF PERIOD.
JKL WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...GEERTSON/CMC
LONG TERM...GINNICK
AVIATION...CMC
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