008  
FXUS63 KLMK 221831  
AFDLMK  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LOUISVILLE KY  
231 PM EDT MON MAY 22 2017  
   
SHORT TERM
 
(THIS EVENING THROUGH TUESDAY NIGHT)  
ISSUED AT 230 PM EDT MON MAY 22 2017  
   
..RAIN CHANCES RETURN LATE TUESDAY
 
 
JUST SOME PASSING HIGH CLOUDS DISTURBING AN OTHERWISE FINE MAY DAY.  
SOUTHWEST FLOW ALOFT WILL KEEP BRINGING IN THOSE CLOUDS TONIGHT INTO  
TOMORROW MORNING. HIGH PRESSURE OVER US NOW WILL SHIFT EASTWARD  
ALLOWING FOR A LIGHT EASTERLY FLOW TONIGHT. A VERY BROAD AREA OF  
LOWER PRESSURE WILL REPLACE IT. GIVEN THE SOUTHWEST FLOW IN PLACE,  
AND PRECIPITABLE WATERS AROUND 1.2-1.3 INCHES IN OUT SOUTH KY  
COUNTIES, CANNOT RULE OUT AN ISOLATED STORM DEVELOPING IN THE LATE  
AFTERNOON/EARLY EVENING HOURS. SOME OF THE BETTER PERFORMING MODELS  
FOR RAIN CHANCES IN THE SHORT-TERM, THE MET/GFS/ECS AS WELL AS OUR  
CONSALL AND CONSRAW MODELS, INDEED BRING IN SOME CHANCES IN THAT  
AREA, SO HAVE TRENDED THE FORECAST TO SLIGHT CHANCES IN THE LATE  
AFTERNOON ALONG AND SOUTH OF A MORGANTOWN TO LEXINGTON, KY LINE.  
 
WEAK ISENTROPIC LIFT KICKS IN TUESDAY NIGHT AHEAD OF THAT BROAD AREA  
OF LOW PRESSURE WHICH LOOKS TO BE DEEPENING OVER FAR WESTERN  
KENTUCKY OVERNIGHT...AS AN UPPER LEVEL LOW DROPS SOUTH OUT OF IOWA.  
PRECIPITABLE WATERS INCREASE TO ABOUT 1.3-1.4 INCHES. THE SURFACE  
LOW WILL LIFT NORTHEAST AS THE UPPER LOW CONTINUES SOUTHWARD BY  
DAYBREAK WEDNESDAY. WITH THE DEEPENING LOW, CANNOT RULE OUT A  
STRONGER CELL DEVELOPING NEAR THE WARM FRONTAL BOUNDARY ASSOCIATED  
WITH THE LOW, AND WE MAY SEE SOME STRONGER WIND GUSTS AS THE LOW  
DEEPENS. THE NAM/GFS DROP THE CENTRAL PRESSURE 7-10 MB FROM 00 TO  
12Z, WHEREAS THE HI-RES WRFS, CMC, 0.1 DEGREE ECMWF ONLY GO 2-4 MB.  
 
ANOTHER POTENTIAL CONCERN BY DAYBREAK WEDNESDAY COULD BE MINOR  
FLOODING, ESPECIALLY IN AREAS RAIN SOAKED A FEW DAYS AGO. MODEL  
QPF IS NOT MORE THAN IN THE 0.5-1 INCH RANGE FOR ANY GIVEN 6-HOUR  
PERIOD.  
 

 
   
LONG TERM
 
(WEDNESDAY THROUGH MONDAY)  
ISSUED AT 230 PM EDT MON MAY 22 2017  
   
..CHILLY WEATHER FOR MID WEEK
 
 
THE SURFACE LOW WILL CONTINUE NORTHWARD BEFORE STALLING OVER  
SOUTHERN INDIANA AS THE UPPER LOW CONTINUES TO PIVOT WITH IT  
SOMEWHERE OVER OUR LONGITUDE WED. AND THU. THE SURFACE LOW SHOULD  
FILL BACK IN SOME. THIS PATTERN HOWEVER WILL CONTINUE TO BRING GOOD  
RAIN CHANCES, CLOUD COVER, AND MUCH COOLER TEMPERATURES, SOME 10-15  
DEGREES BELOW NORMAL.  
 
THE UPPER LOW SHOULD CLEAR EAST OF THE REGION SOME TIME DURING THE  
DAY THURSDAY, ALLOWING A BRIEF WARMUP AS SHORTWAVE RIDGING CROSSES  
THE REGION FRIDAY. A STATIONARY FRONTAL BOUNDARY LOOKS TO SET UP  
SOMEWHERE ALONG THE VICINITY, ORIENTED FROM WNW TO ESE. UPPER LEVEL  
DISTURBANCES PASSING ALONG THIS BOUNDARY COULD LEAD TO SOME MCS  
DEVELOPMENT FOR THE HOLIDAY WEEKEND, BUT SHOULD THE BOUNDARY STAY  
FAR ENOUGH NORTH OF US, ANY ASSOCIATED CONVECTION WOULD BE OVER THE  
NORTH HALF OF THE REGION. BETTER PERFORMING MODELS OVER THE LAST 6  
MONTHS IN THIS TIME PERIOD, CONSALL, MOS GUIDANCE, WMODEL, AND  
THE NEW NBM REGIONAL BLEND, WOULD ARGUE FOR HIGH-END CHANCES TO  
LIKELY RANGE DURING VARIOUS PERIODS FROM SAT-MON. GIVEN SOME  
UNCERTAINTY, WOULD PREFER TO KEEP US OUT OF THE LIKELY RANGE  
THOUGH. THE SUPERBLEND MODEL AGREES WITH THIS THINKING AS WELL, SO  
DID NOT MAKE ANY CHANGES HERE.  
 
TEMPERATURE FORECAST BEYOND THE COLD WED/THU VALUES WILL DEPEND  
GREATLY ON THAT FRONTAL LOCATION AS WELL AS ASSOCIATED CONVECTION.  
SO, THIS PART OF THE FORECAST HAS A LOWER CONFIDENCE.  
 

 
   
AVIATION
 
(18Z TAF ISSUANCE)  
ISSUED AT 140 PM EDT MON MAY 22 2017  
 
VFR WEATHER IS EXPECTED THROUGHOUT THIS TAF PERIOD. SCT-BKN CIRRUS  
IS EXPECTED TO CONTINUE OVERNIGHT INTO TUESDAY. WINDS WILL BE LIGHT  
AND VARIABLE THIS AFTERNOON, BUT GENERALLY OUT OF THE NORTHEAST.  
LIGHT WINDS UNDER 6 KNOTS WILL BECOME MORE EASTERLY OVERNIGHT  
THROUGH TUESDAY MORNING.  
 

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

 
 

 
 
SHORT TERM...RJS  
LONG TERM...RJS  
AVIATION...EBW  
 
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