927  
FXUS63 KLMK 231043  
AFDLMK  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LOUISVILLE KY  
643 AM EDT SAT OCT 23 2021  
   
..UPDATED AVIATION DISCUSSION
 
 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 259 AM EDT SAT OCT 23 2021  
 
PATCHY FOG HAS DEVELOPED EARLY THIS MORNING FROM THE LOWER WABASH  
VALLEY INTO WESTERN KENTUCKY. THIS FOG IS EXPECTED TO DEVELOP  
EASTWARD INTO PORTIONS OF CENTRAL KENTUCKY, ESPECIALLY THE BOWLING  
GREEN/MAMMOTH CAVE REGION WHERE THERE WILL BE THE MOST FOG-FRIENDLY  
COMBINATION OF CLEAR SKIES AND LIGHT WINDS. ANY PATCHY FOG WILL  
DISSIPATE BY MID-MORNING.  
 
OVER THE REMAINDER OF THE DAY A WARM FRONT WILL BECOME INCREASINGLY  
MORE WELL-DEFINED AS IT DRIFTS NORTHWARD ACROSS KENTUCKY. BY THIS  
EVENING IT SHOULD BE IN AN EAST-WEST ORIENTATION JUST NORTH OF THE I-  
64 CORRIDOR. SFC-700MB MOISTURE WILL GRADUALLY INCREASE TODAY AND  
SOME WEAK ISENTROPIC UPGLIDE WILL KICK IN THIS AFTERNOON, LEADING TO  
THE DEVELOPMENT OF SCATTERED LIGHT RAIN SHOWERS BY MID-LATE  
AFTERNOON. RAINFALL AMOUNTS SHOULD BE LESS THAN A TENTH OF AN INCH,  
WITH THE MOST LIKELY AREA TO EXPERIENCE RAIN BEING WEST OF I-65 AND  
NORTH OF I-165.  
 
WITH THE SURFACE BOUNDARY IN THE AREA THERE WILL BE A NORTH-SOUTH  
GRADIENT IN HIGH TEMPERATURES THIS AFTERNOON. MOST LOCATIONS WILL  
HAVE A HIGH IN THE 60S, BUT SOME PLACES IN SOUTHERN INDIANA MAY NOT  
MAKE IT OUT OF THE 50S WHILE A FEW FOLKS ALONG THE TENNESSEE BORDER  
MAY SEE THE MERCURY TOUCH 70.  
 
TONIGHT A BAND OF CONVECTION IS EXPECTED TO DEVELOP AFTER MIDNIGHT  
FROM THE MIDWEST TO THE MIDDLE OHIO VALLEY. THIS ACTIVITY WILL BE IN  
CONJUNCTION WITH THE AFOREMENTIONED SURFACE FRONT AND ON THE LEADING  
EDGE OF A BROAD LOW LEVEL JET. THERE MAY BE ENOUGH INSTABILITY FOR A  
FEW RUMBLES OF THUNDER DURING THE PRE-DAWN HOURS SUNDAY MORNING.  
LOWS WILL BE IN THE 50S, 5 TO 10 DEGREES WARMER THAN NORMAL GIVEN  
OUR POSITION IN THE WARM AIR SOUTH OF THE SURFACE BOUNDARY AND WITH  
WIDESPREAD CLOUD COVER.  
   
LONG TERM
 
(SUNDAY THROUGH FRIDAY)  
ISSUED AT 305 AM EDT SAT OCT 23 2021  
 
SUNDAY - MONDAY...  
 
A STORM SYSTEM OVER THE EAST CENTRAL PLAINS WILL MOVE INTO THE MID  
MISSISSIPPI RIVER VALLEY BY LATER SUNDAY, AND THEN THROUGH THE  
WABASH RIVER VALLEY BY LATE MONDAY. THE ASSOCIATED WARM FRONT WITH  
THIS SYSTEM WILL BE LIFTING ACROSS OUR NORTHERN CWA AT DAYBREAK  
SUNDAY BRINGING NUMEROUS SHOWERS AND ELEVATED THUNDERSTORMS, MAINLY  
CONFINED TO THE NORTHERN HALF OF OUR AREA. BY LATER IN THE AFTERNOON  
AND EVENING, WE'LL LIKELY SEE MOSTLY DRY CONDITIONS AS THE WARM  
SECTOR WILL BE WELL ESTABLISHED OVER SOUTHERN IN AND CENTRAL KY.  
TEMPS WILL EXCEL UNDER THIS REGIME GIVEN A GUSTY/MIXY SW SURFACE  
FLOW AIDING THE ALREADY NOTABLE WARM ADVECTION COMPONENT. LOOK FOR  
HIGHS IN THE MID TO UPPER 70S. A FEW SPOTS ACROSS OUR FAR SW COULD  
FLIRT WITH THE 80 DEGREE MARK. LOOKS LIKE WE'LL SEE PRETTY GUSTY  
GRADIENT WINDS WITH SOME 25-35 MPH VALUES CERTAINLY POSSIBLE.  
 
THE RELATIVE LULL IN ACTIVITY WON'T LAST LONG AS THINGS WILL PICK UP  
AROUND OR SHORTLY AFTER MIDNIGHT. THE EXIT REGION OF A 55 TO 65 KNOT  
MID LEVEL IMPULSE WILL OVERSPREAD THE WARM SECTOR AHEAD OF AN  
APPROACHING COLD FRONT. MEANWHILE, A HEALTHY 50 TO 55 KNOT LOW LEVEL  
JET WILL BE IN PLACE. THIS WILL YIELD A STRONG AND VEERED VERTICAL  
WIND PROFILE THAT WOULD BE MORE THAN SUFFICIENT FOR ORGANIZED SEVERE  
WEATHER. HOWEVER, INSTABILITY IS EXPECTED TO BE MEAGER TO NON-  
EXISTENT BY THE TIME CONVECTION ARRIVES/DEVELOPS IN OUR AREA THANKS  
TO THE NOCTURNAL TIMING. AS A RESULT, EXPECT A WEAKENING TREND WITH  
ANYTHING APPROACHING OUR AREA FROM THE WEST. AT THIS POINT, BELIEVE  
GUSTY WINDS WOULD BE THE MAIN THREAT WITH ANY DECAYING STORMS, AND  
SOME LOW LEVEL STABILITY WOULD KEEP A BIGGER THREAT MITIGATED. THE  
COLD FRONT WON'T ACTUALLY MOVE THROUGH OUR AREA UNTIL LATER MONDAY,  
SO YOU WOULD WANT TO KEEP AN EYE ON SOME INSTABILITY DEVELOPING  
ACROSS OUR EAST MONDAY AFTERNOON. HOWEVER, GIVEN THE CLOUD  
COVER/PRECIPITATION THINK THESE VALUES WOULD ALSO BE QUITE MEAGER.  
ALSO OF NOTE, THE BEST SHEAR WILL BE DISPLACED FARTHER TO THE EAST  
BY THIS TIME AS WELL. CAN'T COMPLETELY RULE OUT SOME SEVERE THREAT  
EITHER SUNDAY NIGHT OR MONDAY, BUT AT THIS POINT IT SEEMS LESS  
LIKELY GIVEN THE INABILITY TO DESTABILIZE BETTER. WILL CONTINUE TO  
MONITOR. THE MARGINAL RISK ACROSS OUR WESTERN THIRD OF THE CWA SEEMS  
REASONABLE.  
 
MONDAY NIGHT - WEDNESDAY...  
 
THE COLD FRONT AND SHORTWAVE WILL BE EXITING OUR EAST BY MONDAY  
NIGHT WITH DRY CONDITIONS TAKING BACK AHOLD OF THE REGION.  
INITIALLY, IT WILL BE DRY NW FLOW ALOFT AND BUILDING SURFACE HIGH  
PRESSURE, HOWEVER THE PROGRESSIVE UPPER PATTERN WILL THEN SHIFT AN  
AMPLIFIED UPPER RIDGE AXIS OVER OUR AREA LATER TUESDAY NIGHT THROUGH  
WEDNESDAY. EITHER WAY, WE STAY DRY THROUGH THIS STRETCH. TEMPS WILL  
BE A BIT COOLER BEHIND THE FRONT, BUT WE'LL STILL SEE LOW TO MID 60S  
ON TUESDAY, AND 65 TO 70 DEGREES BY WEDNESDAY. OVERNIGHT LOWS WILL  
BE IN THE MID TO UPPER 40S TO AROUND 50 EACH NIGHT.  
 
WEDNESDAY NIGHT - FRIDAY...  
 
A DEEP CLOSED LOW IS THEN EXPECTED TO SLIDE INTO OUR AREA AND SLOWLY  
MEANDER EASTWARD OVER THE OHIO OR TENNESSEE RIVER VALLEY TO END THE  
WORK WEEK. THIS IS EXPECTED TO BRING PERIODS OF SHOWERS AND STORMS  
THROUGH THIS STRETCH. TEMPERATURES ARE LIKELY TO STRUGGLE A BIT  
UNDER THE HEAVY CLOUD COVER AND PRECIPITATION WITH HIGHS IN THE  
UPPER 50S AND LOW 60S.  
 

 
   
AVIATION
 
(12Z TAF ISSUANCE)  
ISSUED AT 643 AM EDT SAT OCT 23 2021  
 
IMPACTS: FOG POTENTIAL EARLY THIS MORNING, SHOWERS LATE THIS  
AFTERNOON INTO THIS EVENING, THUNDER LATE TONIGHT INTO SUNDAY  
MORNING.  
 
DISCUSSION: FOG, DENSE IN SPOTS, HAS FORMED EARLY THIS MORNING AT  
BWG AND HNB. AC STREAMING ABOVE HNB HAS HELPED TO KEEP IT IN CHECK  
THERE, BUT CLEARER SKIES IN SOUTHERN KENTUCKY HAVE ALLOWED BWG TO GO  
DOWN TO THE DECK. HOWEVER, ONCE THIS FOG BURNS OFF, THE BULK OF THE  
DAYLIGHT HOURS SHOULD THEN BE VFR IN SOUTHERN INDIANA AND CENTRAL  
KENTUCKY.  
 
THIS AFTERNOON AND EVENING A WARM FRONT LIFTING NORTHWARD ACROSS  
KENTUCKY WILL BRING SCATTERED SHOWERS TO THE REGION. THUNDER WILL  
THEN BE POSSIBLE DURING THE PRE-DAWN HOURS THROUGH MID-MORNING  
SUNDAY AT HNB/SDF.LEX AS WE SIT ON THE EDGE OF A STRENGTHENING LLJ  
INTERACTING WITH THE NEARBY WARM FRONT.  
 
CONFIDENCE: AVERAGE CONFIDENCE ON TIMING OF FOG DISSIPATION THIS  
MORNING. HIGH CONFIDENCE ON FLIGHT RULE CATEGORIES FROM MID-MORNING  
TO MID-EVENING, DECREASING LATE TONIGHT.  
 

 
   
LMK WATCHES/WARNINGS/ADVISORIES
 
 
IN...NONE.  
KY...NONE.  

 
 

 
 
SHORT TERM...13  
LONG TERM...BJS  
AVIATION...13  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab KY Page
The Nexlab IN Page Main Text Page