449
FXUS63 KLMK 182320
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
720 PM EDT SUN OCT 18 2026
..UPDATED AVIATION DISCUSSION
KEY MESSAGES
* PATCHY FROST IS EXPECTED AGAIN TONIGHT, WITH A LOW (20%) CHANCE OF
LOCALIZED FREEZING CONDITIONS IN A FEW LOW-LYING, RURAL AREAS. TO
PROTECT TENDER VEGETATION, COVER OR BRING PLANTS INSIDE.
* HIGH CONFIDENCE (NEAR 100% CHANCE) IN DRY WEATHER ALL WEEK.
ONGOING DROUGHT CONDITIONS, MOST PRONOUNCED OVER SOUTHERN
KENTUCKY, WILL WORSEN IN RESPONSE.
* MILD, FALL-LIKE WEATHER WILL CONTINUE THIS WEEK WITH WARM
AFTERNOONS (UPPER 60S TO MID 70S) FOLLOWED BY CRISP MORNINGS
(UPPER 30S TO MID 40S).
DISCUSSION
ISSUED AT 139 PM EDT SUN OCT 18 2026
*** PATCHY FROST AGAIN TONIGHT? ***
EARLY SUNDAY AFTERNOON, HIGH PRESSURE WAS SPRAWLED ACROSS THE MID-
ATLANTIC AND OHIO VALLEY, MAINTAINING TRANQUIL WEATHER OVER THE
LOCAL AREA. TEMPERATURES, IN THE LOW 60S AT 130PM, WILL WARM ANOTHER
1-3 DEGREES BEFORE SINKING LIKE A ROCK TONIGHT AS CLEAR SKIES AND
LIGHT-CALM WINDS MAKE FOR EXCELLENT RADIATIONAL COOLING. TAKING THIS
TOGETHER WITH DEWPOINTS IN THE UPPER 20S TO MID 30S, WE SUSPECT LOW
TEMPERATURES TOMORROW MORNING - PARTICULARLY IN RURAL AND VALLEY
LOCATIONS - COULD END UP ON THE LOW END OF GUIDANCE. HREF
PROBABILITIES FOR TEMPERATURES UNDER 37 RUN 30-60% IN VALLEY
LOCATIONS ESPECIALLY NEAR AND EAST OF THE I-65 CORRIDOR, WITH A FEW
SPLOTCHES OF LOCALIZED 20+% PROBABILITIES FOR FREEZING TEMPERATURES
IN THESE AREAS AS WELL. GIVEN (1) THE GROWING SEASON HASN'T
OFFICIALLY ENDED YET AND (2) THE POTENTIAL FOR LOWS TO OVERACHIEVE
(BE ON THE LOW END OF THE ENSEMBLE SPECTRUM), WE DECIDED TO ISSUE A
FROST ADVISORY FOR MOST OF THE AREA IN COORDINATION WITH NEIGHBORING
OFFICES. IN ADDITION, WE ADDED "PATCHY" FROST TO THE FORECAST FOR
MUCH OF THE COUNTY WARNING AREA (CWA), AND "AREAS" OF IT IN THE
RIVER VALLEYS.
*** DRY AND MILD THIS WEEK ***
TOMORROW WILL BE SLIGHTLY WARMER AND DRIER AS FORECAST SOUNDINGS
SUGGEST WE MIX A BIT DEEPER, TO NEARLY 850MB (VS ~875-900MB TODAY).
HIGHS ARE SLATED TO APPROACH 70 ACROSS MOST OF THE AREA, WHICH IS
NEAR NORMAL FOR OCTOBER 19TH. LIKE TODAY, TEMPERATURES WILL DROP
QUICKLY WITH THE LOSS OF INCOMING SOLAR RADIATION ("INSOLATION")
AFTER SUNSET, WITH LOWS TUESDAY MORNING ANYWHERE FROM THE MID 30S IN
RURAL, LOW-LYING AREAS TO THE LOW 40S IN URBAN AREAS.
TUESDAY AND ONWARD, WE RINSE AND REPEAT AS THE LARGE-SCALE WEATHER
PATTERN REMAINS RATHER SIMILAR WITH WEAK RIDGING ACROSS THE CENTRAL
US AND A CUTOFF LOW AIMLESSLY DRIFTING IN THE WESTERN ATLANTIC. THE
ONE CAVEAT MIGHT BE A FEW MID-HIGH CLOUDS TUESDAY INTO WEDNESDAY AS
DETERMINISTIC MODELS SHOW A WEAK SHORTWAVE DRIFTING SOUTHEAST
THROUGH THE REGION. CONSIDERING THIS FEATURE WILL (1) RAIN OUT A LOT
OF ITS (PACIFIC) MOISTURE IN THE HIGH TERRAIN ACROSS THE GREAT BASIN
AND (2) DRY VIA DOWNSLOPING IN THE HIGH PLAINS, WE'RE NOT EXPECTING
ANY RAIN WITH IT, BUT THE CLOUDS MAY KEEP US FROM RADIATING QUITE AS
MUCH AND CONSEQUENTLY LIMIT FROST POTENTIAL TUESDAY NIGHT. IN
ADDITION, THEY MAY KEEP US FROM MIXING QUITE AS DEEP ON TUESDAY.
STILL RH VALUES ARE FORECAST TO DROP INTO THE UPPER 20S TO MID 30S
EACH DAY THROUGH AT LEAST TUESDAY, WHICH WOULD RAISE FIRE WEATHER
CONCERNS IF WE HAD ANY WIND; THANKFULLY, WINDS SHOULD GENERALLY STAY
LESS THAN 10 MPH GIVEN CONTINUED SURFACE HIGH PRESSURE OVER THE AREA.
THE PATTERN BECOMES INCREASINGLY AMPLIFIED LATE WEEK INTO THE
WEEKEND, AS THE CENTRAL US RIDGE GETS SQUEEZED BETWEEN A TROUGH OVER
THE NORTHEAST AND ANOTHER ONE LIFTING OUT OF THE GREAT BASIN. THIS
"OMEGA BLOCK," WITH THE UPPER RIDGE CENTERED OVER THE MISSISSIPPI
VALLEY, WILL KEEP CONDITIONS DRY AND SLIGHTLY WARMER THAN NORMAL
RIGHT THROUGH THE WEEKEND. THE ONLY IMPACT WE CAN ASCERTAIN DURING
THIS EXTENDED PERIOD WOULD BE WORSENING DROUGHT CONDITIONS DUE TO
THIS CONTINUED DRY WEATHER. CLIMATOLOGICALLY, NORMAL WOULD BE JUST
UNDER 1 INCH OF RAIN PER WEEK DURING MID-LATE OCTOBER, SO WE'D NEED
TO SEE AT LEAST THAT MUCH (IDEALLY MORE) TO REVERSE THE ONGOING
DROUGHT, WHICH AS OF LAST WEEK'S USDM UPDATE WAS CLASSIFIED AS D1
"MODERATE" ACROSS SOUTHERN KENTUCKY AND D0 "ABNORMALLY DRY" ACROSS
MOST OF THE REMAINDER OF THE STATE.
AVIATION /00Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 720 PM EDT SUN OCT 18 2026
HIGH PRESSURE WILL CONTINUE TO DOMINATE THE FORECAST DURING THE
UPCOMING TAF PERIOD, WITH VFR CONDITIONS EXPECTED. LIGHT EAST WINDS
SHOULD GENERALLY BE 5 KT OR LESS OVERNIGHT TONIGHT. WINDS SHOULD
BECOME MORE VARIABLE IN DIRECTION DURING THE DAY ON MONDAY BUT
REMAIN LIGHT.
LMK WATCHES/WARNINGS/ADVISORIES
KY...FROST ADVISORY FROM 1 AM EDT /MIDNIGHT CDT/ TO 9 AM EDT /8 AM
CDT/ MONDAY FOR KYZ024-025-027>043-045>049-053>057-
062>067-074>078-081-082.
IN...FROST ADVISORY FROM 1 AM EDT /MIDNIGHT CDT/ TO 9 AM EDT /8 AM
CDT/ MONDAY FOR INZ076>079-083-084-089>092.
DISCUSSION...JRB
AVIATION...CSG
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