722  
FXUS63 KPAH 262329  
AFDPAH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PADUCAH KY  
629 PM CDT THU APR 26 2018  
   
UPDATE
 
 
ISSUED AT 629 PM CDT THU APR 26 2018  
 
THE AVIATION SECTION HAS BEEN UPDATED FOR THE 00Z TAF ISSUANCE.  
 

 
   
SHORT TERM
 
(TONIGHT THROUGH SATURDAY NIGHT)  
ISSUED AT 200 PM CDT THU APR 26 2018  
 
HIGH CONFIDENCE IN A RAINFREE FORECAST THROUGH THE SHORT TERM.  
THERE WILL BE A COUPLE OF WEAK AND MOISTURE STARVED MID LVL TROFS  
(AND ASSOCIATED SURFACE FRONTS) PASS THROUGH FROM NW TO SE LATER  
TONIGHT AND AGAIN FRIDAY NIGHT. WILL MAINLY SERVE TO HALT ANY  
WARMING TREND HEADING INTO THE WEEKEND. NORTHWEST BREEZES 10 TO  
20 MPH WILL KEEP TEMPS IN THE 60S TO NEAR 70 ON SATURDAY AFTERNOON  
AND COULD HINDER SMALL CRAFT ATTEMPTING TO NAVIGATE AREA RIVERS  
AND LAKES. SOME GUSTS TO 25 MPH OR SO SEEM LIKELY.  
 
IT IS NOW LOOKING AS THOUGH THE MAIN SURFACE HIGH SETTLING INTO  
THE LOWER MIDWEST AND OHIO VALLEY SATURDAY NIGHT WILL BE MORE OF  
CANADIAN ORIGIN THAT EARLIER THOUGHT. ALONG WITH CLEAR SKIES AND  
CALM WINDS, WE COULD END UP WITH SOME FROST CONCERNS HEADING INTO  
EARLY SUNDAY MORNING. HIGHEST CHANCES WOULD OF OCCURRENCE NOW  
SEEM TO BE ALONG AND NORTH OF I-64 CORRIDOR, PERHAPS INTO THE  
PENNYRILE OF NW KY.  
   
LONG TERM
 
(SUNDAY THROUGH THURSDAY)  
ISSUED AT 200 PM CDT THU APR 26 2018  
 
GOOD FORECAST CONFIDENCE WITH THIS FORECAST PACKAGE. MAIN FACTOR TO  
GENERAL INCREASE IN FORECAST CONFIDENCE IS THE LARGE SCALE STABILITY  
OF THE RIDGE AND TROUGH PATTERN DEVELOPING OVER THE U.S.  
 
THE VAST MAJORITY OF THE EXTENDED FORECAST PERIOD WILL BE DRY WITH  
TEMPERATURES RANGING FROM NEAR NORMAL UP TO 10 DEGREES ABOVE NORMAL  
FOR LATE APRIL AND EARLY MAY.  
 
THE NEXT INTRODUCTION OF POPS/WEATHER WILL BE ASSOCIATED WITH THE  
LEADING EDGE OF A FULL LATITUDE, SLOWLY PROGRESSING, POSITIVE TILT  
TROUGH THROUGH THE CENTRAL U.S. ON BETWEEN WEDNESDAY AND FRIDAY OF  
NEXT WEEK.  
 
THE 12Z THURSDAY ECMWF AND CANADIAN GUIDANCE SUGGEST THAT SOME PRE-  
FRONTAL ACTIVITY MOVING INTO THE NORTHWEST PART OF THE WFO PAH  
FORECAST AREA (SOUTHEAST MISSOURI/SOUTHWEST ILLINOIS) AS EARLY AS  
WEDNESDAY. HOWEVER THE GREATEST QPF (RAINFALL AMOUNT) POTENTIAL  
WILL BE THURSDAY AND FRIDAY. CANNOT RULE OUT SOME TRAINING  
THUNDERSTORMS WITH THIS SCENARIO, ALONG WITH SOME FLOODING POTENTIAL  
GIVEN THE CURRENT DETERMINISTIC OUTPUT FROM THESE MODELS.  
 
BLENDED THE ECMWF AND CANADIAN GUIDANCE WITH THE REGIONALLY  
INITIALIZED GRIDDED MODEL BLEND FOR TEMPERATURES TO REFLECT THE  
RANGE DURING RAIN VS. NON-RAIN DAYS.  
 
THE ATMOSPHERIC RIVER FROM THE GULF OF MEXICO WILL BE WIDE OPEN  
DURING THE MIDDLE OF NEXT WEEK, WITH WESTERN EDGE OF HIGHER SPECIFIC  
HUMIDITY VALUES IMPINGING TO WESTERN SECTIONS OF SOUTHEAST MISSOURI  
AND SOUTHWEST ILLINOIS AS EARLY AS WEDNESDAY. BASED ON THE EARLIER  
00Z THURSDAY GEFS/GFS GUIDANCE, THE MAXIMUM FLUX OF INTEGRATED WATER  
VAPOR WOULD BE CENTERED OVER THE WFO PAH FORECAST AREA MAY 3RD AND  
4TH. WILL NEED TO MONITOR FOR HEAVY RAIN/FLOODING POTENTIAL DURING  
THAT TIME PERIOD. REGARDLESS, A PROLONGED TRANSPORT AND DEPOSITION  
OF THE RAIN OVER THE MISSOURI AND MISSISSIPPI RIVER BASINS MAY  
PRODUCE SOME ELEVATED WATER LEVELS ON THE MISSISSIPPI AND ITS  
TRIBUTARIES LATE NEXT WEEK OR THE FOLLOWING WEEK.  
 
CIPS EXTENDED ANALOG GUIDANCE IS NOT SUGGESTIVE AT THIS TIME FOR ANY  
HIGH END SEVERE POTENTIAL, WITH THE HIGHEST POTENTIAL (23%) FOR  
GENERAL/LONG-LIVED TORNADO PROBABILITIES LIMITED TO THE EDGE OF OUR  
SOUTHEAST MO/SOUTHWEST IL COUNTIES THROUGH THE MAY 1ST-MAY 4TH TIME  
PERIOD. THE HIGHEST PROBABILITIES FOR THE SAME AREA ARE ASSOCIATED  
WITH JUST A SINGLE SEVERE REPORT (60%). WITH THESE SYSTEMS AT THE  
VERY END OF THE FORECAST PERIOD, IT WILL BE DIFFICULT TO PINPOINT  
ANYTHING FURTHER, GIVEN MODEL VARIABILITY AND MESOSCALE  
INFLUENCES.  
 

 
   
AVIATION
 
 
ISSUED AT 629 PM CDT THU APR 26 2018  
 
THE TAFS ARE VFR. A WEAK COLD FRONTAL WIND SHIFT WILL MOVE THROUGH  
THE REGION EARLY FRIDAY. A LIGHT WEST OR SOUTHWEST WIND WILL  
DEVELOP LATER THIS EVENING AND THEN SHIFT TO THE WEST NORTHWEST  
BEHIND THE FRONT FRIDAY MORNING. SOME GUSTS INTO THE TEENS WILL BE  
POSSIBLE IN THE AFTERNOON. AS FOR CLOUDS, THE LATEST GUIDANCE HAS  
SOME MOISTURE AROUND 5KFT THROUGH THE PERIOD IN THE SOUTHWEST AND  
THROUGHOUT THE AREA DURING THE DAY. CEILINGS ARE NOT EXPECTED AT  
THIS TIME.  
 

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

 
 

 
 
UPDATE...DRS  
SHORT TERM...GM  
LONG TERM...SMITH  
AVIATION...DRS  
 
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