319  
FXUS63 KPAH 251141  
AFDPAH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PADUCAH KY  
640 AM CDT TUE APR 25 2017  
   
UPDATE
 
 
ISSUED AT 640 AM CDT TUE APR 25 2017  
 
UPDATED AVIATION DISCUSSION FOR 12Z TAFS.  
 

 
   
SHORT TERM
 
(TODAY THROUGH THURSDAY NIGHT)  
ISSUED AT 320 AM CDT TUE APR 25 2017  
 
MAIN NEAR TERM FORECAST CONCERN IS THE POTENTIAL FOR THUNDERSTORMS,  
SOME POSSIBLY STRONG TO SEVERE, LATE WEDNESDAY AFTERNOON AND  
WEDNESDAY NIGHT. FORECAST CONFIDENCE IS RELATIVELY HIGH THROUGH  
THURSDAY NIGHT WITH GENERALLY GOOD OVERALL MODEL AGREEMENT.  
 
DRY AND UNSEASONABLY WARM WEATHER WILL CONTINUE TODAY AS SOUTHERLY  
FLOW PICKS UP BETWEEN HIGH PRESSURE DEPARTING TO THE EAST AND LOW  
PRESSURE DEVELOPING OVER THE GREAT PLAINS. WITH ABUNDANT SUNSHINE  
AND SOUTHERLY WINDS, TEMPERATURES SHOULD HAVE NO TROUBLE REACHING  
THE 80 DEGREE MARK ACROSS MUCH OF THE AREA THIS AFTERNOON. SOUTH  
WINDS OVER THE WESTERN 2/3 OF THE AREA WILL BE QUITE STRONG BY  
LATE MORNING AND AFTERNOON--SUSTAINED AROUND 15 MPH WITH OCCASIONAL  
GUSTS OF 25 TO 30 MPH.  
 
SHORTWAVE ENERGY CURRENTLY ENTERING THE PACIFIC NORTHWEST IS  
FORECAST TO DROP SOUTHEAST INTO THE SOUTHERN PLAINS BY WEDNESDAY  
BEFORE TAKING ON A NEGATIVE TILT AND PIVOTING NORTHEAST ACROSS THE  
MID AND UPPER MISSISSIPPI VALLEY WEDNESDAY NIGHT. THE APPROACH AND  
PASSAGE OF THIS TROUGH AND ITS ASSOCIATED COLD FRONTAL BOUNDARY  
WILL PROVIDE THE FOCUS FOR SHOWER AND THUNDERSTORM DEVELOPMENT  
WEDNESDAY AND WEDNESDAY NIGHT. WITH FORECAST MODEL SOUNDINGS  
INDICATING THE PRESENCE OF A STRONG MID LEVEL CAPPING INVERSION  
THROUGH MUCH OF THE DAYTIME HOURS WEDNESDAY, ANY CONVECTIVE  
DEVELOPMENT DURING THE DAY WOULD LIKELY BE ELEVATED AND RELATED TO  
LOW LEVEL CONVERGENCE ACROSS SOUTHEAST MISSOURI AND FAR SOUTHWEST  
ILLINOIS. THE MAIN EVENT WILL BE FOCUSED FROM LATE WEDNESDAY  
AFTERNOON INTO WEDNESDAY NIGHT AS THE COLD FRONT MAKES PASSAGE.  
 
WITH DEW POINTS IN THE LOWER 60S, DECENT INSTABILITY AND 0-6KM  
BULK SHEAR OF 50 TO 60 KNOTS, STRONG TO SEVERE THUNDERSTORMS  
REMAIN POSSIBLE, ESPECIALLY ACROSS THE WESTERN HALF OF THE AREA  
WHERE THE BETTER INSTABILITY IS FORECAST. THE STORMS MAY HAVE  
TROUBLE MAINTAINING THEIR STRENGTH AS INSTABILITY BEGINS TO WANE  
BY LATE EVENING AND AFTER MIDNIGHT WEDNESDAY NIGHT. WHILE SOME  
DISCRETE CELLS ARE POSSIBLE EARLY ON OVER SOUTHEAST MISSOURI,  
DEEP-LAYERED SHEAR VECTORS ORIENTED NEARLY PARALLEL TO THE LINE OF  
FORCING SUGGESTS THE ACTIVITY SHOULD QUICKLY BECOME LINEAR EARLY  
IN THE EVENING. DAMAGING WINDS APPEAR TO BE THE PRIMARY CONCERN,  
WHILE LARGE HAIL AND AN ISOLATED TORNADO CANNOT BE RULED OUT WITH  
ANY DISCRETE CELLS EARLY ON--ESPECIALLY WEST OF THE MISSISSIPPI  
RIVER.  
 
ANY LINGERING SHOWERS SHOULD TAPER OFF EARLY THURSDAY MORNING AS THE  
STORM SYSTEM DEPARTS TO THE EAST. MUCH OF THURSDAY SHOULD ACTUALLY  
BE DRY, ALBEIT COOLER IN THE WAKE OF THE FRONT. AFTER HIGHS IN THE  
MID 70S TO LOWER 80S ON WEDNESDAY, HIGHS ON THURSDAY ARE FORECAST IN  
THE MID TO UPPER 60S. THE NEXT CHANCE OF SHOWERS SHOULD HOLD OFF  
UNTIL LATE THURSDAY NIGHT AT THE EARLIEST AS THE FRONT BEGINS TO  
RETURN NORTH AS A WARM FRONT.  
   
LONG TERM
 
(FRIDAY THROUGH MONDAY)  
ISSUED AT 320 AM CDT TUE APR 25 2017  
 
WELL, MUCH OF THE EXTENDED LOOKS TO BE SUMMED UP AS VERY WET AND  
UNSETTLED AS DEEP SWLY FLOW BECOMES ESTABLISHED TO THE WEST OF A MID  
LEVEL BLOCKING HIGH PRESSURE SYSTEM OFF THE SOUTHEAST U.S. COAST. A  
SURFACE FRONT WILL LIKELY BECOME STATIONARY SOMEWHERE CLOSE TO THE  
OHIO RIVER EARLY IN THE PERIOD, PARALLEL TO THE MID LEVEL FLOW. THE  
FRONT WILL LIKELY BE A FOCUS FOR THE HIGHEST SHOWER/THUNDERSTORM  
CHANCES FRIDAY/FRIDAY NIGHT.  
 
THE FRONT IS THEN EXPECTED TO LIFT BACK TO THE NORTH AS A WARM FRONT  
OVER THE WEEKEND AS A SURFACE LOW LIFTS NORTHEAST FROM THE SOUTHERN  
PLAINS. THIS WILL PROBABLY OFFER THE HIGHEST CHANCES FOR STRONG TO  
SEVERE THUNDERSTORMS AS A COLD FRONT IS EVENTUALLY DRUG EAST ACROSS  
THE REGION SOMETIME ON SUNDAY. IN THE MEANTIME, THE POTENTIAL EXISTS  
FOR SEVERAL ROUNDS OF THUNDERSTORMS WITH HEAVY RAINFALL FRIDAY INTO  
SATURDAY AS PW VALUES SOAR TO VERY HIGH LEVELS FOR THIS TIME OF  
YEAR, POSSIBLY 1.75 TO 2" OVER ABOUT THE WESTERN THIRD OF THE  
FORECAST AREA. MULTIPLE SHORT WAVES MAY EJECT NORTHEAST OUT OF THE  
BASE OF THE DEEP H50 TROF. THE TIMING OF ANY IMPULSES WILL BE  
DIFFICULT AT BEST, SO WILL NOT GET TOO SPECIFIC IN THAT REGARD.  
RIGHT NOW, IT APPEARS THE HIGHEST RAINFALL TOTALS MAY BE FOCUSED  
OVER SOUTHEAST MO INTO SOUTHWEST IL, BUT AGAIN, THIS COULD BE  
SUBJECT TO CHANGE WITH TIME. SOME PLACES ACROSS THE REGION MAY BE  
SUBJECT TO SEVERAL INCHES OF RAINFALL BY THE TIME ALL IS SAID AND  
DONE SUNDAY NIGHT. REGARDING THE SEVERE STORM POTENTIAL, SPC HAS  
ALREADY INCLUDED A GOOD PORTION OF THE FORECAST AREA IN A 15% RISK  
FOR SUNDAY.  
 
THE REGION SHOULD FINALLY GET A BREAK BY EARLY NEXT WEEK AS HIGH  
PRESSURE BUILD IN BEHIND THE FRONTAL PASSAGE. TEMPERATURES WILL  
LIKELY STAY ON THE MILD SIDE AS THE HIGH ACTUALLY BUILDS IN FROM THE  
SOUTHERN PLAINS STATES.  
 

 
   
AVIATION
 
 
ISSUED AT 640 AM CDT TUE APR 25 2017  
 
VFR CONDITIONS ARE EXPECTED AT ALL SITES THROUGH MUCH OF THE PERIOD.  
LIGHT SOUTHERLY WINDS WILL INCREASE TO 10 TO 15 KNOTS BY LATE  
MORNING AND AFTERNOON. GUSTS OF 15 TO 20 KNOTS WILL BE COMMON BY  
AFTERNOON, REACHING AS HIGH AS 25 KNOTS OVER SOUTHWEST ILLINOIS AND  
SOUTHEAST MISSOURI, INCLUDING KCGI. SOUTHERLY WINDS SHOULD SUBSIDE  
TO AROUND 10 KNOTS TONIGHT. LOW CLOUDS WILL BEGIN TO SPREAD ACROSS  
THE AREA LATE TONIGHT. INCLUDED AN MVFR CEILING AT KCGI AND KPAH  
AFTER 08-09Z.  
 

 
   
PAH WATCHES/WARNINGS/ADVISORIES
 
 
IL...NONE.  
MO...NONE.  
IN...NONE.  
KY...NONE.  

 
 

 
 
SHORT TERM...RJP  
LONG TERM...GM  
AVIATION...RJP  
 
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