321
FXUS63 KLMK 140231
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
931 PM EST MON JAN 13 2025
KEY MESSAGES
* VERY COLD TEMPERATURES TUESDAY AND WEDNESDAY WITH MORNING LOWS IN
THE SINGLE DIGITS AND TEENS. WEDNESDAY MORNING COULD FEATURE
TEMPERATURES BELOW ZERO IN SOME LOCATIONS.
* THERE IS A CHANCE FOR MINOR SNOW ACCUMULATIONS ON TUESDAY FOR
SOUTHERN INDIANA AND NORTH-CENTRAL KENTUCKY. SNOW AMOUNTS ARE
EXPECTED TO BE LESS THAN 1 INCH.
* MILDER TEMPERATURES FRIDAY, WITH WIDESPREAD RAIN FRIDAY NIGHT
INTO SATURDAY LIKELY ENDING AS SNOW SATURDAY NIGHT AND SUNDAY.
UPDATE
ISSUED AT 931 PM EST MON JAN 13 2025
DRY WEATHER AND CLEAR SKIES WILL CONTINUE OVERNIGHT AS HIGH PRESSURE
BUILDS OVER THE REGION. OPTIMAL RADIATIONAL COOLING, COLD AIR
ADVECTION, SNOWPACK-RELATED COOLING EFFECTS, AND DECREASING
DEWPOINTS WILL CONTRIBUTE TO VERY COLD TEMPERATURES IN THE SINGLE
DIGITS ALONG AND NORTH OF THE OHIO RIVER AND IN THE TEENS TO THE
SOUTH. NO CHANGES WERE NEEDED WITH THIS UPDATE AS AFTERNOON FORECAST
REMAINS ON TRACK.
SHORT TERM /THROUGH TUESDAY/
ISSUED AT 318 PM EST MON JAN 13 2025
TEMPERATURES HAVE BEEN NEARLY STEADY TODAY IN THE UPPER 20S AND
LOWER 30S AFTER FALLING THROUGH THE PRE-DAWN HOURS AS A COLD FRONT
SWEPT THROUGH. SFC HIGH PRESSURE HAS BEEN FILTERING IN FROM THE
WEST, WHICH HAS KEPT A NW FLOW AND STRONG CAA REGIME IN PLACE. FOR
THE REST OF TONIGHT, MOSTLY CLEAR SKYCOVER AND LIGHTER WINDS WILL
COINCIDE WITH THE SNOWPACK AND CAA, WHICH WILL PROMOTE FRIGID
TEMPERATURES BY TOMORROW MORNING. LOW TEMPERATURES GETTING DOWN INTO
THE TEENS ARE EXPECTED, WITH MAYBE A FEW ISOLATED POCKETS OF SINGLE
DIGITS POSSIBLE IN ANY TYPICAL COOL SPOTS OR SHELTERED AREAS. NBM
PAINTS A 40-50% PROBABILITY OF TEMPS IN THE SINGLE DIGITS NORTH OF
THE WKY/BG PARKWAYS, WITH EVEN HIGH PROBS TO THE NORTH OF OUR
FORECAST AREA. WIND CHILLS NEAR ZERO ARE FORECAST FOR THE SAME
AREAS.
ANOTHER REINFORCING COLD FRONT WILL BRING A QUICK-HITTING CLIPPER
SYSTEM THROUGH THE OHIO VALLEY TOMORROW. WHILE THE BETTER FORCING
AND MOISTURE WILL BE ACROSS INDIANA, THERE WILL LIKELY BE ENOUGH
ALONG AND NORTH OF THE I-64 CORRIDOR TO SQUEEZE OUT SOME LIGHT SNOW
SHOWERS DURING THE LATER MORNING AND EARLY AFTERNOON. MOISTURE WILL
BE RATHER LIMITED, SO CONFIDENCE ON EVEN BEING ABLE TO MEASURE ANY
PRECIP REMAINS LOW. WILL CONTINUE TO CARRY A 20-25% POP FOR THE
CHANCE FOR A LIGHT DUSTING FOR SOUTHERN INDIANA AND NORTH-CENTRAL
KENTUCKY. ANY SNOW SHOULD BE RATHER FLUFFY AND DRY WITH SNOW RATIOS
IN THE 18-20:1 RANGE, AND SHOULD HAVE AN EASIER TIME STICKING TO
ELEVATED SURFACES THAN THE ROADS. WHILE AIR AND SFC TEMPS COULD
SUPPORT MINOR IMPACTS, THE VERY LOW WATER CONTENT WILL FURTHER LIMIT
THE POTENTIAL.
LONG TERM /TUESDAY NIGHT THROUGH MONDAY/
ISSUED AT 318 PM EST MON JAN 13 2025
TUESDAY NIGHT THROUGH THURSDAY NIGHT...
=============================================
SUB ZERO TEMPERATURES EXPECTED TUESDAY NIGHT
=============================================
UPPER LEVEL SHORTWAVE TROUGH AXIS IS FORECAST TO PASS TO OUR
EAST/NORTHEAST TUESDAY NIGHT. BEHIND THIS FEATURE, STRONG ARCTIC
HIGH PRESSURE WILL BE BUILDING INTO THE REGION WITH SKIES CLEARING
OUT AND WINDS GOING LIGHT/VARIABLE. TUESDAY NIGHT LOWS WILL BE
BRUTALLY COLD WITH GOOD RADIATIONAL COOLING LIKELY. NBM GUIDANCE
HERE IS PROBABLY TOO HIGH GIVEN OUR ICE/SNOW COVER FROM PREVIOUS
STORMS. FOR NOW, PLAN ON GOING -2 TO 5 FOR AREAS NORTH OF THE BG/WK
PARKWAYS. I FULLY EXPECT THAT SOME OF OUR COLDER SITES (BRANDENBURG
AND CYNTHIANA) PROBABLY WILL GO SOMEWHERE IN BETWEEN -5 TO MAYBE -8
OR SO. TEMPS WILL BE REALLY SENSITIVE TO THE CLEAR SKIES AND
BOUNDARY LAYER WINDS OVER THOSE SITES. SOUTH OF THE PARKWAYS, LOWS
OF 5-10 WILL BE COMMON. MOSTLY SUNNY SKIES ARE EXPECTED ON
WEDNESDAY WITH HIGHS IN THE 25-30 RANGE ACROSS SOUTHERN IN AND THE
NORTHERN HALF OF KENTUCKY. SOUTH OF THE PARKWAYS, HIGHS IN THE 28-
32 DEGREE RANGE ARE EXPECTED. WE'LL GET BACK INTO A SOUTHERLY FLOW
ON WEDNESDAY NIGHT, SO TEMPS ARE NOT EXPECTED TO COOL OFF THAT MUCH.
LOWS IN THE UPPER SINGLE DIGITS TO THE LOWER TEENS ARE EXPECTED
ACROSS SOUTHERN IN AND NORTHERN KENTUCKY. SOUTHERN KY SHOULD SEE
LOWS IN THE 15-20 DEGREE RANGE.
WARM ADVECTION PATTERN SHOULD BE IN FULL SWING FOR THURSDAY WITH
MOSTLY SUNNY SKIES AND AFTERNOON TEMPS WARMING INTO THE UPPER 30S TO
THE LOWER 40S ACROSS SOUTHERN IN AND NORTHERN KY. SOUTHERN KY
SHOULD SEE READINGS IN THE 40-45 DEGREE RANGE. LOWS THURSDAY NIGHT
WILL ONLY DROP INTO THE 25-30 DEGREE RANGE.
FRIDAY THROUGH MONDAY...
BY FRIDAY, THE GLOBAL MODEL SOLUTIONS SHOW A SPLIT FLOW PATTERN
ACROSS THE WESTERN CONUS WITH A ZONAL BUT CONFLUENT FLOW DOWNSTREAM
ACROSS THE OHIO VALLE INTO THE EASTERN US. HIGH PRESSURE WILL BE
ANCHORED TO OUR EAST, KEEPING US IN A SOUTHERLY FLOW REGIME.
MOISTURE WILL WORK NORTHWARD AND SOME WEAK ISENTROPIC LIFT MAY BE
ENOUGH TO PRODUCE SCATTERED RAIN SHOWERS BY LATE FRIDAY AFTERNOON
INTO FRIDAY EVENING. HIGHS FRIDAY SHOULD RANGE FROM THE LOW-MID 40S
OVER SOUTHERN INDIANA AND NORTHERN KENTUCKY TO THE UPPER 40S/LOWER
50S ACROSS SOUTHERN KY. OVERNIGHT LOWS FRIDAY NIGHT ARE EXPECTED TO
DROP INTO THE 35-40 DEGREE RANGE.
FOR SATURDAY AND SUNDAY AN UPPER TROUGH AXIS OVER THE PLAINS WILL
HEAD EASTWARD AND PUSH A FRONTAL BOUNDARY INTO THE REGION ON
SATURDAY. WIDESPREAD CLOUD COVER AND LIGHT TO MODERATE CHILLY RAIN
SHOWERS ARE EXPECTED HERE. HIGHS SATURDAY WILL BE IN THE 40-45
DEGREE RANGE IN THE NORTH WITH 45-50 SOUTH OF THE PARKWAYS.
THINGS BECOME MORE INTERESTING SATURDAY NIGHT INTO SUNDAY AS THE
MODELS STRUGGLE TO DECIDE ON HOW FAR EAST THE FRONTAL BOUNDARY WILL
GET. TODAY'S RUNS SUGGEST THE LEAD SHORTWAVE TROUGH WILL GET EAST OF
THE REGION, BUT ANOTHER ONE UP STREAM WILL SWING THROUGH ON SUNDAY.
WITH COLD AIR IN PLACE, THE SECOND WAVE LOOKS TO BRING SOME LIGHT
SNOWS BACK INTO THE REGION FOR SUNDAY AND PERHAPS INTO MONDAY.
AS USUAL FOR THIS TIME RANGE, THERE REMAINS CONSIDERABLE UNCERTAINTY
WITH REGARDS TO THE EXACT EVOLUTION AND QPF AMOUNTS WITH THE SECOND
WAVE. CURRENT ENSEMBLE PROBABILITIES FROM THE GEFS AND EPS SHOW
LESS THAN A 20% CHANCE OF EXCEEDING AN INCH OF SNOW BY SUNDAY
EVENING. HOWEVER, THAT IS LIKELY TO CHANGE (UP/DOWN) IN THE COMING
DAYS. IT WILL LIKELY BE LATE THURSDAY OR FRIDAY BEFORE WE HAVE SOME
GOOD FORECAST CONVERGENCE FOR THE LATE WEEKEND SNOW POTENTIAL.
BEHIND THIS SYSTEM, A RETURN OF COLDER AIR IS EXPECTED. HIGHS
SUNDAY WILL LIKELY BE IN THE UPPER 20S/LOWER 30S, WITH HIGHS ON
MONDAY STRUGGLING TO MAKE 20-25 DEGREES.
==================================================
EXTENDED FORECAST DISCUSSION
==================================================
LOOKING BEYOND MONDAY, A VERY COLD WEATHER PATTERN IS EXPECTED TO
PERSIST ACROSS THE CENTRAL AND EASTERN CONUS FOR THE REMAINDER OF
JANUARY. HEMISPHERICALLY, THE MJO IS CURRENTLY IN PHASE 1 AND IS
FORECAST TO MAKE AN ORBIT INTO PHASE 2 BY THE START OF THE EXTENDED
FORECAST PERIOD, EVENTUALLY MAKING AN ORBIT INTO PHASE 3/4 TOWARD
FEBRUARY. THIS OVERALL PATTERN FAVORS COLD WEATHER FOR OUR REGION.
TELECONNECTION AT THE BEGINNING OF THE PERIOD ARE EXPECTED TO
FEATURE A -NAO/-AO/-EPO/-PNA PATTERN WHICH GENERALLY FAVORS COLD.
WHILE THE NAO/AO MAY TREND MORE POSITIVE WITH TIME, THE EPO LOOKS
REMAIN NEGATIVE WITH THAT RIDGE BUILDING INTO AK WHICH WILL CONTINUE
TO FAVOR DOWNSTREAM TROUGHING ACROSS THE EASTERN US.
WITH THE COLD PATTERN IN PLACE, WE'LL HAVE TO WATCH TO SEE HOW THIS
AFFECTS THE STORM TRACK. THE STORM TRACK LOOKS TO BE SHIFTED TO THE
SOUTH, BUT JUST HOW FAR SOUTH REMAINS UNCERTAIN. SOMETIMES IN
STRONG ARCTIC AIRMASSES, YOU CAN GET A REALLY SUPPRESSED STORM TRACK
WHICH JUST KEEPS US COLD/DRY. OTHER TIMES, THE STORM TRACK ISN'T
ALL THAT SUPPRESSED.
THE SOUTHERN STREAM LOOKS TO REMAIN ACTIVE THROUGH THIS PERIOD, SO
WINTER WEATHER AROUND HERE IS NOT DONE BY ANY MEANS. SIGNAL
ANALYSIS SUGGESTS SIGNAL PASSAGES AROUND 1/23-24, AND ANOTHER,
POSSIBLY STRONGER SIGNAL PASSAGE BY 1/27-1/28. THE 1/27-1/28 SIGNAL
HAS BEEN QUITE STRONG IN THE ANALYSIS SINCE MID-DECEMBER AND SHOULD
BE WATCHED CLOSELY.
AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 639 PM EST MON JAN 13 2025
IMPACTS/CONFIDENCE:
- HIGH CONFIDENCE IN BREEZY WINDS TUESDAY AFTERNOON
- MEDIUM TO HIGH CONFIDENCE IN MVFR CEILINGS TUESDAY AFTERNOON
DISCUSSION...SURFACE HIGH PRESSURE STRETCHING ACROSS THE AREA
TONIGHT WILL PROVIDE VFR CONDITIONS AND LIGHT WINDS AT ALL
TERMINALS. FOR TOMORROW, AN APPROACHING COLD FRONT WILL SPEED UP THE
SURFACE FLOW WITH GUSTS AROUND 15-20 KNOTS IN THE AFTERNOON.
ALTHOUGH THERE IS LIMITED MOISTURE ACCOMPANYING THE FRONTAL
BOUNDARY, A FEW FLURRIES MIGHT STILL OCCUR FOR THE NORTHERN
TERMINALS IN THE AFTERNOON WITH NO SIGNIFICANT ACCUMULATIONS OR
VISIBILITY IMPACTS EXPECTED. ON THE OTHER HAND, MOS AND HI-RES
GUIDANCE HINT AT A BRIEF PERIOD OF MVFR CEILINGS WITH THE FRONTAL
PASSAGE. DECREASING WNW WINDS AND VFR CEILINGS WILL PREDOMINATE BY
THE END OF THE FORECAST PERIOD.
LMK WATCHES/WARNINGS/ADVISORIES
KY...NONE.
IN...NONE.
UPDATE...ALL
SHORT TERM...CJP
LONG TERM...MJ
AVIATION...ALL
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