813  
FXUS63 KPAH 182319  
AFDPAH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PADUCAH KY  
619 PM CDT SAT MAY 18 2013  
   
UPDATE
 
 
ISSUED AT 614 PM CDT SAT MAY 18 2013  
 
UPDATE FOR 00Z AVIATION ONLY  
 

 
   
SHORT TERM
 
(TONIGHT THROUGH MONDAY NIGHT)  
ISSUED AT 306 PM CDT SAT MAY 18 2013  
 
WITH WHATS LEFT OF AN UPPER LOW JUST TO THE NORTH AND EAST OF OUR  
CWA...SCATTERED SHOWERS ARE POSSIBLE THIS AFTERNOON INTO THE EARLY  
EVENING HOURS OVER THE EXTREME NORTHEAST SECTIONS OF OUR CWA.  
 
MODELS CONTINUE TO INDICATE A SCENARIO TONIGHT THAT STILL MAKES NO  
SENSE...BUT ALL MODELS ARE SHOWING (FOR THE MOST PART) THE SAME  
THING. THEY SHOW A NW-SE ORIENTED SFC TROUGH DRAPED ACROSS OUR  
CWA...AN H5 RIDGE BUILDING ACROSS THE AREA...AND A NW-SE ORIENTED  
BAND OF LIGHT PRECIPITATION/QPF DEVELOPING ALONG AND/OR NEAR THE  
BOUNDARY. NORMALLY A RIDGE BUILDING OVERHEAD TENDS TO  
SQUASH/SUPPRESS ANY CHANCES FOR PRECIPITATION...BUT WITH THE  
PRESENCE OF THE SFC TROUGH AND THE FACT THAT ALL MODELS CONTINUE TO  
CRANK OUT A BAND OF LIGHT PRECIP...DECIDED TO KEEP SMALL POPS  
OVERNIGHT INTO SUNDAY MORNING JUST IN CASE.  
 
DONT EXPECT ANY PRECIP SUNDAY AFTERNOON AND EVENING...BUT WITH THE  
RIDGE HAVING MOVED TO THE EAST OF THE AREA...IT WILL ALLOW PRECIP  
CHANCES TO MAKE THEIR WAY BACK INTO THE FAR NORTHWESTERN AND WESTERN  
SECTIONS OF OUR CWA LATE SUNDAY NIGHT AS THE NEXT WEATHER SYSTEM  
APPROACHES FROM THE CENTRAL PLAINS. AS THE SYSTEM DRAWS NEARER TO  
THE LOWER OHIO VALLEY...PRECIPITATION CHANCES WILL INCREASE MONDAY  
INTO MONDAY NIGHT.  
   
LONG TERM
 
(TUESDAY THROUGH SATURDAY)  
ISSUED AT 306 PM CDT SAT MAY 18 2013  
 
ECMWF...GFS AND GEM ALL SHOW A SURFACE LOW OVER THE UPPER MIDWEST  
00Z WEDNESDAY...MOVING OVER THE LOWER GREAT LAKES REGION BY 00Z  
THURSDAY. GEM IS BIT FASTER THAN THE ECMWF WITH THE ASSOCIATED COLD  
FRONT AND PRECIP TIMING. GFS IS A LITTLE SLOWER THAN THE ECMWF AND  
LESS DEFINED WITH PRECIP ENDING BECAUSE IT DEVELOPS A SECOND LOW  
WHICH SLIDES ALONG THE FRONT LATE WEDNESDAY NIGHT INTO EARLY  
THURSDAY. THIS GFS SOLUTION IS NOT CONSISTENT WITH ITS PREVIOUS  
RUN...AND PREFERRED TO LEAN TOWARD A ECMWF/GEM SOLUTION. SHOWER AND  
THUNDERSTORM CHANCES WILL INCREASE FROM WEST TO EAST ON TUESDAY WITH  
THE APPROACH OF THE FRONT...WITH THE BEST CHANCES FOR MORE  
SIGNIFICANT QPF TUESDAY NIGHT INTO WEDNESDAY. WENT WITH LIKELY POPS  
FOR THE ENTIRE PAH FORECAST AREA TUESDAY NIGHT...WITH LIKELY POPS  
CONTINUING FOR OUR EASTERN THIRD OF COUNTIES ON WEDNESDAY. MODELS  
INDICATE THE FRONT WILL STALL OUT OVER OR JUST SOUTH OF THE FA FOR  
WEDNESDAY NIGHT INTO THURSDAY NIGHT...SO KEPT SOME SLIGHT TO LOW  
CHANCE POPS IN THE FORECAST FOR THESE TIME PERIODS.  
 
GEM AND ECMWF BOTH SHOW HIGH PRESSURE BUILDING SOUTH OUT OF  
CENTRAL/EASTERN CANADA FRIDAY AND INTO THE WEEKEND. GFS ALSO SHOWS  
THIS FEATURE...BUT IS MUCH SLOWER BUILDING IT SOUTH AND THUS HANGS  
ON TO LIGHT PRECIP IN THE AREA INTO FRIDAY. LEANED TOWARD TO THE  
MORE AGGRESSIVE ECMWF/GEM SOLUTIONS AND WENT WITH DRY CONDITIONS  
FRIDAY INTO SATURDAY. THE HIGH WILL KEEP THE AREA IN A NORTHERLY  
FLOW...WHICH WILL PROVIDE COOLER CONDITIONS WITH SLIGHTLY BELOW  
SEASONAL NORMALS INTO AT LEAST THE FIRST PART OF THE HOLIDAY  
WEEKEND.  
 

 
   
AVIATION
 
 
ISSUED AT 614 PM CDT SAT MAY 18 2013  
 
MOS GUIDANCE IS TRYING TO BRING MVFR FOG IN BY SUNSET AT MOST  
SITES. WAS NOT READY TO GO THAT FAR BUT CONSIDERING LAST NIGHTS  
FOG WENT AHEAD AND INTRODUCED IT. IN CONTRAST TO NORMAL MOS  
ACTUALLY BRINGS PAH EVV AND OWB DOWN EARLIER AND INTO IFR CAT  
OVNGT. INTRODUCED MVFR FOG AND TEMPO SOME IFR FOG AFTER 6Z. WILL  
MONITOR CLOSELY FOR FOG DEVELOPMENT TIMING AND INTENSITY. LIGHT  
SOUTH WINDS OVNGT AND A BIT GUSTY AT KCGI AFTER 18Z SUNDAY.  
 

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

 
 

 
 
UPDATE...KH  
AVIATION...KH  
 
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