678  
FXUS63 KLMK 202303  
AFDLMK  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LOUISVILLE KY  
603 PM EST WED FEB 20 2019  
   
..UPDATED AVIATION DISCUSSION
 
 
   
FORECAST UPDATE
 
 
ISSUED 500 PM EST WED FEB 20 2019  
 
THE FLOOD WATCH HAS BEEN CANCELLED A LITTLE AHEAD OF SCHEDULE AS THE  
HEAVIEST RAINS HAVE PUSHED WELL EAST OF THE AREA, AND CALLS TO  
SEVERAL COUNTIES HAVE REVEALED SOME IMPROVING CONDITIONS IN REGARDS  
TO FLOODED ROADWAYS. WATER LEVELS WILL STILL REMAIN HIGH ALONG  
CREEKS, STREAMS, AND RIVERS THROUGH THE END OF THE WEEK.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH THURSDAY)  
ISSUED AT 227 PM EST WED FEB 20 2019  
 
THE SURFACE BOUNDARY THAT ENTERED WESTERN KENTUCKY THIS AFTERNOON  
WILL CONTINUE TO MOVE EASTWARD ACROSS CENTRAL KENTUCKY AND SOUTHERN  
INDIANA THIS EVENING, PUSHING SCATTERED SHOWERS AND ISOLATED  
THUNDERSTORMS AHEAD OF IT. THE REGION SHOULD BE FREE OF RAIN BY  
MIDNIGHT. CLOUDS WILL LIKELY LINGER THROUGH THE NIGHT, THOUGH, AS  
MOISTURE GETS TRAPPED UNDER A SHARP INVERSION. A FEW PATCHES OF  
DRIZZLE AREN'T OUT OF THE QUESTION, ESPECIALLY IN THE BLUE GRASS.  
LOW TEMPERATURES WILL MOSTLY BE IN THE MIDDLE 30S, BUT A FEW SPOTS  
IN SOUTHERN INDIANA MAY DIP INTO THE LOWER 30S, ESPECIALLY IF THE  
CLOUDS BREAK UP SOONER THAN EXPECTED.  
 
THOUGH RAINFALL AMOUNTS WILL BE RELATIVELY LIGHT THIS EVENING, THERE  
ARE MANY SPOTS AROUND THE AREA THAT ARE STILL WAITING FOR EARLIER  
MINOR FLOODING TO RECEDE, SO WILL HOLD ON TO THE FLOOD WATCH WHILE  
THE RAIN IS STILL FALLING. THE WATCH WILL BE CLEARED EARLY FROM WEST  
TO EAST AS THE FRONT PASSES THROUGH.  
 
TOMORROW HIGH PRESSURE NOSING IN FROM THE MIDWEST WILL GIVE US A  
MUCH WELCOME BREAK FROM THE WET AND UNSETTLED WEATHER. WE SHOULD  
ACTUALLY SEE SOME PARTIAL SUNSHINE WITH A LIGHT BREEZE AND  
SEASONABLE HIGHS IN THE UPPER 40S AND LOWER 50S.  
   
LONG TERM
 
(THURSDAY NIGHT THROUGH WEDNESDAY)  
ISSUED AT 325 PM EST WED FEB 20 2019  
   
..ADDITIONAL HEAVY RAINFALL AND THUNDERSTORMS THIS WEEKEND
 
 
THURSDAY'S DRY WEATHER WILL BE SHORT-LIVED AS RAIN MOVES BACK INTO  
SOUTHERN KENTUCKY THURSDAY EVENING, THEN DRIFTS NORTH TOWARD THE  
OHIO RIVER BY FRIDAY MORNING. THIS IS IN RESPONSE TO RIPPLES MOVING  
THROUGH THE SOUTHWEST FLOW ALOFT, AND AMOUNTS WILL BE LIGHT DUE TO  
LOW LEVEL NORTHEAST FLOW AROUND A SURFACE HIGH DRIFTING EASTWARD  
ACROSS THE GREAT LAKES REGION.  
 
HOWEVER, HOT ON THE HEELS OF THIS WEAK SYSTEM, A VIGOROUS TROF OVER  
THE SOUTHWEST U.S. WILL MAKE ITS PRESENCE KNOWN FOR THE WEEKEND. AS  
A SURFACE LOW DEVELOPS OVER THE SOUTHERN PLAINS AHEAD OF THE DIGGING  
UPPER TROF, THE GULF OPENS BACK UP, PRIMING THE LOWER ATMOSPHERE  
WITH MOISTURE TO COMBINE WITH MID AND UPPER MOISTURE AND ENERGY  
MOVING IN AS THE UPPER SYSTEM MOVES INTO THE MISSISSIPPI VALLEY  
SATURDAY. THIS TIGHTLY WOUND SYSTEM WILL BRING STRONG SOUTHERLY  
WINDS TO THE AREA THAT WILL NOT ONLY SEND TEMPERATURES INTO THE 60S  
ACROSS THE AREA, BUT DEW POINTS INTO THE 50S AND LOWER 60S AS WELL.  
 
WITH THE AIRMASS SATURATED FROM THE SURFACE THROUGH 40K FEET,  
RAINFALL RATES WILL BE HIGH AT TIMES, BUT THE THICK CLOUDS WILL ALSO  
WORK TO LIMIT INSTABILITY SOMEWHAT, PREVENTING ANY INSOLATION TO  
HEAT THE SURFACE. CURRENT GUIDANCE SHOWS A WEAK THERMAL CAP AT  
850MB, WHICH COULD SUPPRESS THUNDER DEVELOPMENT SOMEWHAT, BUT WITH  
THE STRONG LOW LEVEL JET IN PLACE - AND A 140KT JET ALOFT, SYNOPTIC  
FORCING COULD OVERCOME THIS CAP. IF THAT HAPPENS, NOT ONLY WILL  
THERE BE THE THREAT FOR TORRENTIAL RAINFALL, BUT FOR SEVERE  
THUNDERSTORMS SATURDAY AS 60KT WINDS LOOK TO BE JUST A FEW THOUSAND  
FEET ABOVE THE SURFACE, AND ANY MIXING DOWN WOULD WREAK HAVOC ON  
TREES ALREADY STRUGGLING TO STAND IN THE QUICKSAND-LIKE TOPSOIL  
ACROSS THE AREA. FORTUNATELY, WITH NO LEAVES YET ON THE TREES, THEY  
WON'T HAVE THAT ADDED WEIGHT AND WIND RESISTANCE TO WORSEN THE  
SITUATION.  
 
THE CENTER OF BOTH THE SURFACE AND UPPER LOW WILL MOVE INTO THE  
GREAT LAKES BY SUNDAY MORNING, AND RAIN WILL END ACROSS THE AREA  
WITH A TRAILING COLD FRONT MOVING THROUGH WITH IT. A RARE SET OF DRY  
DAYS FOLLOW WITH NEARLY ZONAL UPPER LEVEL FLOW BEFORE THE NEXT  
CHANCE OF RAIN RETURNS WEDNESDAY. THIS FAR OUT, HOWEVER, IT REMAINS  
TO BE SEEN EXACTLY HOW SIGNIFICANT THIS WILL BE, WITH THE MAJOR MID-  
LONG RANGE MODELS ALL DOING THEIR OWN THINGS BY THEN.  
 
TEMPERATURE-WISE THROUGH THE PERIOD, HIGHS WILL BE IN THE 50S FRIDAY  
BEFORE WARMING INTO THE 60S SATURDAY, THEN DROP BACK INTO THE 50S  
SUNDAY AND THE 40S MONDAY BEFORE REBOUNDING. LOW TEMPERATURES WILL  
BE IN THE 30S TO LOWER 40S THURSDAY NIGHT, THEN STAY ABOVE 40  
THROUGH SUNDAY NIGHT, WHEN THEY WILL DROP BACK INTO THE 20S BEFORE  
RETURNING TO THE 30S FOR THE REMAINDER OF THE PERIOD.  
 

 
   
AVIATION
 
(00Z TAF ISSUANCE)  
UPDATED AT 600 PM EST WED FEB 20 2019  
 
SHOWERS AHEAD OF A FRONT ARE BEGINNING TO PUSH EAST OF THE I-65  
CORRIDOR, AND SHOULD PUSH PAST THE I-75 CORRIDOR OVER THE THE NEXT  
SEVERAL HOURS. POST-FRONTAL STRATUS WILL LINGER THROUGH THE  
OVERNIGHT HOURS, WITH GRADUAL CLEARING OCCURRING FROM WEST TO EAST.  
AREAS NEAR THE I-75 CORRIDOR MAY NOT SEE CLEARING UNTIL AFTER  
SUNRISE TOMORROW.  
 
ONE LOW-CONFIDENCE CONCERN FOR TONIGHT IS THE FOG POTENTIAL WEST OF  
I-65. MOST GUIDANCE DOES NOT DEVELOP FOG, BUT SOME (LIKE THE NAM)  
HIT DENSE FOG REALLY HARD OVERNIGHT IN AREAS THAT SEE CLEARING.  
THINK WINDS WILL STAY UP ENOUGH OVERNIGHT BEHIND THE FRONT TO KEEP  
THE LOWER BOUNDARY LAYER MIXED ENOUGH TO KEEP FOG FROM BEING TOO  
MUCH OF AN ISSUE. THIS WILL BE MONITORED IN SUBSEQUENT FORECAST  
UPDATES.  
 

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

 
 

 
 
UPDATE...DM  
SHORT TERM...13  
LONG TERM...JBS  
AVIATION...DM  
 
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