623  
FXUS63 KLMK 270647  
AFDLMK  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LOUISVILLE KY  
147 AM EST SAT FEB 27 2021  
   
FORECAST UPDATE
 
 
ISSUED AT 147 AM EST SAT FEB 27 2021  
 
REALLY IMPRESSIVE 925-850 MB MOISTURE TRANSPORT CURRENTLY OCCURRING  
FROM MIDDLE TN INTO SOUTHERN KY. PW VALUES HAVE PUSHED ABOVE 1.2  
INCHES ACROSS SOUTHERN KY. KOHX 0621Z VAD WIND PROFILE CONFIRMED A  
50 KT SOUTHWESTERLY LLJ AT 3 KFT, WHICH IS HELPING PRODUCE ROBUST  
WAA AND ISENTROPIC LIFT. IR CLOUD TOP TEMPERATURES HAVE BEEN  
STEADILY COOLING OVER THE PAST COUPLE OF HOURS OVER THE LAKE  
CUMBERLAND REGION, AND SCATTERED LIGHTNING STRIKES HAVE BEEN NOTED  
ON BOTH SIDES OF THE TN BORDER.  
 
GIVEN THE ENVIRONMENT AND THE CURRENT POSITION OF THE HEAVY RAIN  
BAND, HAVE INCREASED QPF BETWEEN 06-12Z THIS MORNING A FAIR AMOUNT.  
THE FORCING AND MOISTURE TRANSPORT WILL LIKELY KEEP MODERATE TO  
HEAVY RAIN OVER THE LAKE CUMBERLAND REGION THROUGH 11-12Z. 6-HOURLY  
RAINFALL AMOUNTS OF 1-1.5 INCHES ARE LIKELY IN MONROE, CUMBERLAND,  
CLINTON, AND RUSSELL COUNTIES. QPF HAS BEEN INCREASED IN OTHER  
ADJACENT COUNTIES AS WELL, SUCH AS ALLEN, BARREN, METCALFE, AND  
ADAIR. RAINFALL TOTALS WILL LIKELY COME UP SHY OF 3-HR FFG VALUES,  
BUT WILL NEED TO CONTINUE TO MONITOR CLOSELY FOR POTENTIAL MINOR  
FLOODING THIS MORNING.  
 
ISSUED AT 940 PM EST FRI FEB 26 2021  
 
EARLIER COVERAGE OF RAIN SHOWERS ACROSS NORTHERN KENTUCKY AND  
SOUTHERN INDIANA HAS MOVED ON OFF TO THE NORTHEAST. HOWEVER, NEXT  
BATCH OF PRECIPITATION IS CURRENTLY DEVELOPING TO THE SOUTHWEST OF  
THE REGION WITH LIGHT RETURNS ALREADY MOVING INTO SOUTHERN KY.  
CURRENT TEMPERATURES WERE GENERALLY AROUND 40 ACROSS SOUTHERN IN AND  
NORTHERN KY. A BIT OF A TEMPERATURE GRADIENT WAS SEEN ACROSS  
SOUTHERN KY (MAINLY SOUTH OF THE CUMBERLAND PARKWAY) WHERE  
TEMPERATURES INCREASE FROM THE LOWER 40S ALONG THE CUMBERLAND  
PARKWAY BUT INCREASE TO NEAR 50 ALONG THE KY/TN BORDER.  
 
CURRENT FORECAST FOR THE OVERNIGHT PERIOD LOOKS GOOD. UPPER LEVEL  
SHORT WAVE TROUGH AXIS OVER WESTERN TX IS FORECAST TO MOVE EASTWARD  
WITH A LOW-LEVEL JET AXIS DEVELOPING OVERNIGHT FROM THE MS DELTA  
REGION UP THROUGH THE TN AND LOWER OH VALLEYS. BEST CHANCES OF  
RAINFALL LOOK TO BE ACROSS SOUTHERN KY OVERNIGHT WITH A DECREASING  
COVERAGE OF RAINFALL AS ONE HEADS NORTH OF THE WK/BG PARKWAYS.  
RAINFALL AMOUNTS OF A QUARTER TO HALF INCH STILL LOOK GOOD ACROSS  
THE SOUTHERN THIRD OF KY OVERNIGHT WITH LESSER AMOUNTS NORTH OF THE  
PARKWAYS.  
 
AS FAR AS CONVECTIVE POTENTIAL GOES, MODEL SOUNDINGS SHOW A  
RELATIVELY STABLE BOUNDARY LAYER THIS EVENING WITH A BIT GOOD CINH  
ACROSS THE REGION. HOWEVER, LOW-LEVEL JET PUSHING INTO THE AREA  
OVERNIGHT SHOULD PROVIDED A DECENT AMOUNT OF LIFT RESULTING IN GOOD  
PARCEL ASCENT ABOVE THE TOP OF THE MORE STABLE BOUNDARY LAYER. MODEL  
SOUNDINGS ILLUSTRATE THAT WELL WITH SOME POTENTIAL FOR ELEVATED  
INSTABILITY. SO REALLY CAN'T RULE OUT SOME RUMBLES OF THUNDER OR A  
FEW LIGHTNING STRIKES DOWN ALONG THE KY/TN BORDER AREA AND INTO THE  
LAKE CUMBERLAND REGION WITH CONVECTION OVERNIGHT.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH SATURDAY)  
ISSUED AT 228 PM EST FRI FEB 26 2021  
 
AFTER SOME SCATTERED LIGHT RAIN SHOWERS IN THE AREA THIS EVENING,  
COVERAGE SHOULD INCREASE OVERNIGHT AS A WAVE OVER WEST TEXAS THIS  
AFTERNOON MOVES INTO THE OH VALLEY AND A LOW LEVEL JET DEVELOPS FROM  
NORTHERN MISSISSIPPI TO EASTERN KENTUCKY. AN ISOLATED RUMBLE OF  
THUNDER WILL BE POSSIBLE NEAR THE TENNESSEE STATE LINE, AND THOUGH  
INSTABILITY WILL BE MEAGER, CAN'T COMPLETELY RULE OUT SOME BRIEF  
VERY SMALL HAIL NEAR LAKE CUMBERLAND AFTER MIDNIGHT IN THE MOST  
ROBUST CONVECTION. RAINFALL TOTALS TONIGHT INTO EARLY SATURDAY  
MORNING WILL BE VERY LIGHT IN MOST LOCATIONS, BUT THE LAKE  
CUMBERLAND/DALE HOLLOW LAKE AREAS COULD SEE BETWEEN HALF AN INCH AND  
AN INCH OF RAIN, MOSTLY BETWEEN MIDNIGHT AND DAWN. TEMPERATURES  
TONIGHT WON'T MOVE MUCH, WITH READINGS IN THE 40S.  
 
ON SATURDAY ANY LINGERING SHOWERS SHOULD MOVE OFF TO THE EAST EARLY  
IN THE MORNING AND LEAVE US WITH A MOSTLY DRY DAY THANKS TO WEAKLY  
RISING PRESSURES AND HEIGHTS, BEFORE MORE SHOWERS MOVE IN FROM THE  
WEST TOWARDS EVENING. ATMOSPHERIC MOISTURE PROFILES SHOW LOW CLOUDS  
HANGING AROUND THROUGH THE DAY, WITH BETTER CHANCES FOR MORE  
CLOUDINESS AS ONE GOES SOUTH TOWARDS SOUTHERN KENTUCKY. MODEL  
GUIDANCE IS IN TWO GROUPS FOR MAX TEMPS TOMORROW AFTERNOON -- ONE  
WARMER AND ONE COOLER. WILL GO WITH THE COOLER GUIDANCE GIVEN CLOUDS  
AND A LACK OF STRONG LOW LEVEL WARM ADVECTION...BUT ON THE WARM SIDE  
OF THAT COOLER GROUP WITH INCREASING THICKNESSES. THAT RESULTS IN  
HIGHS MOSTLY IN THE 50S, WHICH IS STILL SEVERAL DEGREES ABOVE NORMAL  
FOR LATE FEBRUARY.  
   
LONG TERM
 
(SATURDAY NIGHT THROUGH FRIDAY)  
ISSUED AT 300 PM EST FRI FEB 26 2021  
   
..HEAVY RAINFALL LIKELY SATURDAY NIGHT - SUNDAY
 
 
SATURDAY NIGHT - SUNDAY NIGHT...  
 
THE NEXT AND LIKELY MOST SIGNIFICANT WAVE OF PRECIPITATION IS  
EXPECTED TO MOVE INTO THE AREA LATE SATURDAY NIGHT THROUGH SUNDAY.  
SYNOPTIC PATTERN WILL FEATURE A WESTERN TROUGH AND EASTERN RIDGE,  
WITH DEEP SOUTHWESTERLY FLOW CONTINUING OVER THE OH VALLEY AS A  
SERIES OF SHORTWAVES MOVE THROUGH THE LARGE-SCALE TROUGH. AT THE  
SURFACE, EXPECT TO FIND A FRONTAL BOUNDARY DRAPED ACROSS THE DEEP  
SOUTH THAT WILL GRADUALLY LIFT NORTHWARD AS A WARM FRONT INTO THE  
LOWER OH VALLEY LATE SATURDAY NIGHT AHEAD OF A SYSTEM DEVELOPING TO  
THE WEST. AS THE WAVES OF ENERGY INTERACT WITH THIS FRONTAL  
BOUNDARY, EXPECT WIDESPREAD RAINFALL TO DEVELOP OVER THE AREA  
STARTING LATE SATURDAY NIGHT AND CONTINUING THROUGH THE DAY SUNDAY.  
 
INITIALLY, MODEL SOUNDINGS INDICATE A DRY LAYER BETWEEN 850-500 MB,  
BUT AS A 40-50 KT SOUTHWESTERLY 850 MB JET NOSES INTO THE AREA,  
AMPLE MOISTURE WILL BE TRANSPORTED IN AND EXPECT THE COLUMN TO  
QUICKLY SATURATE. A STRONG ATMOSPHERIC RIVER WILL BE IN PLACE AS  
WELL WITH THE NAEFS AND ECMWF ENS INDICATING IVT VALUES IN THE 99TH  
PERCENTILE ADVECTING INTO THE AREA. THIS WILL LEAD TO A SURGE IN  
PWATS ACROSS CENTRAL KY AND SOUTHERN IN WITH VALUES INTO THE 1.25 -  
1.4 INCH RANGE, WHICH IS ABOVE THE 99TH PERCENTILE FOR THIS TIME OF  
YEAR. EXPECT THERE TO BE SOME ELEVATED INSTABILITY AS WELL, WITH  
MUCAPE VALUES OF UP TO ~100 -200 J/KG POSSIBLE INTO SUNDAY.  
 
IN GENERAL, MODEL GUIDANCE SEEMS TO BE CONVERGING ON THE IDEA OF A  
BAND OF MODERATE TO HEAVY RAINFALL SETTING UP ALONG/IN THE VICINITY  
OF THE OHIO RIVER LATE SATURDAY NIGHT INTO SUNDAY MORNING AS THE  
FRONT HANGS UP IN THIS VICINITY. RAINFALL IS THEN EXPECTED TO SLOWLY  
SHIFT SOUTHEASTWARD THROUGHOUT THE DAY ON SUNDAY AS A COLD FRONT  
PRESSES INTO THE AREA IN ASSOCIATION WITH A CLOSED LOW LIFTING  
NORTHEAST THROUGH THE UPPER GREAT LAKES REGION. EXPECT THE HEAVIEST  
RAINFALL TO OCCUR IN THE 0228/06-12Z TIMEFRAME OVER PORTIONS OF  
SOUTHERN IN AND NORTHERN KY WITH 6-HOUR TOTALS AROUND 1 INCH  
POSSIBLE. ELSEWHERE ACROSS CENTRAL AND SOUTHERN KY, TOTALS OF AROUND  
0.50-0.75 INCHES ARE POSSIBLE. DURING THE MID MORNING HOURS FROM  
0228/12-18Z, AN ADDITIONAL INCH OF RAINFALL IS POSSIBLE ACROSS  
PORTIONS OF NORTHERN AND CENTRAL KY WITH 0.25 - 0.50 INCHES POSSIBLE  
ACROSS SOUTHERN IN AND SOUTHERN KY. BY SUNDAY AFTERNOON FROM 0228/18-  
00Z, THE HEAVIEST BAND OF PRECIPITATION WILL HAVE PROGRESSED  
SOUTHEAST TOWARDS THE LAKE CUMBERLAND REGION WITH ANOTHER 0.50 -  
1.00 INCHES POSSIBLE IN THAT VICINITY AND UP TO A QUARTER INCH FOR  
AREAS TO THE NORTH.  
 
OVERALL, THIS BRINGS RAINFALL TOTALS FRIDAY THROUGH SUNDAY INTO THE  
1-3 INCH RANGE WITH LOCALLY HIGHER 3+ INCH AMOUNTS POSSIBLE. AT THIS  
POINT IN TIME THERE REMAINS SOME UNCERTAINTY IN WHERE EXACTLY THE  
BAND OF HEAVIEST PRECIPITATION WILL SET UP, AS SOME OF THE HEAVIEST  
RATES AND TOTALS WILL LIKELY BE DRIVEN BY AREAS OF CONVECTION AND  
TRAINING STORMS. ADDITIONALLY, EXPECT A SHARP GRADIENT IN QPF NORTH  
OF THE OHIO RIVER ON THE NORTH SIDE OF THE HEAVIER PRECIP BAND.  
WHILE 3- AND 6-HR FFG VALUES ARE GENERALLY BETWEEN 1.5 - 3.0 INCHES,  
ANY AREAS THAT SEE CONVECTIVE RAIN RATES OR TRAINING OF STORMS COULD  
SEE SOME MINOR FLOODING ISSUES DEVELOP. IN COORDINATION WITH  
NEIGHBORS, WILL THEREFORE GO AHEAD AND ISSUE A FLOOD WATCH FOR  
POINTS GENERALLY ALONG AND SOUTH OF THE OHIO RIVER STARTING 11 PM  
EST SATURDAY NIGHT AND CONTINUING INTO EARLY MONDAY MORNING AS  
RAIN MOVES OUT OF THE CUMBERLAND REGION. LOOKING AT RIVERS, AT  
THIS TIME AREAS MOST LIKELY TO SEE SOME MINOR RIVER FLOODING  
DEVELOP WOULD BE POINTS ALONG THE GREEN, LICKING AND KENTUCKY  
RIVERS.  
 
MONDAY AND BEYOND...  
 
BY MONDAY, EXPECT TO BEGIN DRYING OUT ACROSS THE REGION AS SURFACE  
HIGH PRESSURE BUILDS IN FROM THE NORTHWEST WITH MOSTLY DRY WEATHER  
EXPECTED TO CONTINUE INTO TUESDAY. BY TUESDAY AFTERNOON, BEGIN TO  
SEE SIGNIFICANT DIFFERENCES BETWEEN MODEL GUIDANCE. LOOKING AT WPC  
CLUSTER ANALYSIS, THREE OF THE FOUR CLUSTERS SUGGEST DRY WEATHER FOR  
TUESDAY NIGHT WHILE THE FOURTH CLUSTER (CONSISTING OF 1/3 OF THE  
TOTAL ENSEMBLE MEMBERS) SUGGESTS WIDESPREAD PRECIPITATION.  
SIMILARLY, FOR THURSDAY INTO FRIDAY WE SEE TWO DRY CLUSTERS AND TWO  
WET CLUSTERS, WITH THE TOTAL ENSEMBLE MEMBERS BEING SPLIT ABOUT  
50/50. AS A RESULT, WILL CARRY SOME SLIGHT CHANCE POPS DURING THESE  
TWO TIMEFRAMES UNTIL WE CAN BEGIN TO SEE SOME BETTER AGREEMENT AMONG  
MODEL GUIDANCE.  
 

 
   
AVIATION
 
(06Z TAF ISSUANCE)  
ISSUED AT 1256 AM EST SAT FEB 27 2021  
 
WIDESPREAD SHOWERS ALONG WITH A FEW THUNDERSTORMS ARE SPREADING  
NORTHEAST ACROSS SOUTH-CENTRAL KY, MAINLY FROM BWG EASTWARD. LEX  
WILL BEGIN THE PERIOD WITH PREVAILING -RA AS WELL, BUT ONLY  
ISOLATED/BRIEF LIGHT RAIN IS POSSIBLE AT HNB AND SDF. RAIN SHOWERS  
ARE LIKELY AT BWG AND LEX THROUGH 10-11Z OR SO BEFORE THE BAND  
SHIFTS SOUTHEAST OF THOSE TERMINALS. BETWEEN 06-09Z, EXPECT THE  
LOWER CEILINGS OVER WEST-CENTRAL KY AND HNB TO GRADUALLY FILL IN  
FURTHER EAST. THINK MVFR WILL RETURN AT LEX VERY SOON WITH IFR  
LIKELY BY 09Z. BWG SHOULD SEE CEILINGS DROP QUICKER.  
 
AFTER 11Z, A LULL IN RAINFALL IS EXPECTED THROUGH MUCH OF THE DAY AT  
THE FOUR TAF SITES. LATE THIS EVENING, AFTER 02Z OR SO, A BAND OF  
MODERATE TO HEAVY RAINFALL WILL LIFT NORTH ACROSS CENTRAL KY. THE  
HEAVIEST RAIN IS EXPECTED GENERALLY ON EITHER SIDE OF THE OHIO RIVER  
BETWEEN 06-12Z SUN. SOME SCATTERED THUNDERSTORMS WILL ALSO BE  
POSSIBLE ALONG WITH BRIEF IFR/LIFR VSBYS IN HEAVIER RAIN/STORMS.  
 

 
   
LMK WATCHES/WARNINGS/ADVISORIES
 
 
IN...FLOOD WATCH FROM LATE TONIGHT THROUGH MONDAY MORNING FOR INZ084-  
089>092.  
 
KY...FLOOD WATCH FROM LATE TONIGHT THROUGH MONDAY MORNING FOR  
KYZ023>031-033>043-045>049-053>057-061>067-070>078-081-082.  
 

 
 

 
 
UPDATE...MJ/EBW  
SHORT TERM...13  
LONG TERM....JML  
AVIATION...EBW  
 
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