177  
FXUS63 KPAH 250747  
AFDPAH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PADUCAH KY  
247 AM CDT SUN JUN 25 2017  
   
SHORT TERM
 
(TODAY THROUGH TUESDAY NIGHT)  
ISSUED AT 246 AM CDT SUN JUN 25 2017  
 
FORECAST CONFIDENCE FOR THE MONDAY/MONDAY NIGHT WEATHER SYSTEM IS  
ABOVE 60 PERCENT, WITH THE ONLY CAVEAT BEING THE TIMING OF THE  
GREATEST COVERAGE OF PRECIPITATION ACROSS THE WFO PAH FORECAST  
AREA.  
 
THE SIGNAL FOR THE ENTRANCE AND PASSAGE OF PRECIPITATION ACROSS  
THE FOR LATE MONDAY AND MONDAY NIGHT REMAINS CONSISTENT. HOWEVER,  
THE CHALLENGE FOR PRECIPITATION COVERAGE LIES WITH THE EVOLUTION  
OF THE SHARPENING TROUGH ROTATING AROUND THE GREAT LAKES LOW  
DURING THE AFOREMENTIONED TIME PERIOD. THE BLENDED MODEL GUIDANCE  
INITIALIZATION DID GENERATE A HIGHER POP (PROBABILITY OF  
PRECIPITATION) WITHIN THE WFO PAH FORECAST AREA. GIVEN THE  
SHARPENING OF THE BAROCLINIC ZONE AHEAD OF THE MIDDLE/UPPER LEVEL  
TROUGH, HAD TO CONSIDER RAISING POP CHANCES ACROSS A BROADER AREA  
MONDAY EVENING, CLOSER TO THE CANADIAN MODEL SOLUTION.  
 
REGARDLESS OF THE MODEL GUIDANCE USED, THERE DOES NOT SEEM TO BE  
MUCH OF A SURFACE REFLECTION OF THE UPPER TROUGH, IN FACT, SURFACE  
HIGH PRESSURE REMAINS DOMINANT. INSTABILITY IS ALSO A FACTOR. USED  
A BLEND OF GFS/CANADIAN LIFTED INDEX VALUES FROM SURFACE TO 850 MB  
BASES TO FIND MOST UNSTABLE AIR. THIS SUGGESTS THAT LAPSE RATE  
CHANGES WILL BE FOCUSED ALONG CHANNELED VORTICITY ZONES WITH THE  
CYCLONIC FLOW ALOFT.  
 
GIVEN THE ELEVATED NATURE OF THE PRECIPITATION, AMOUNTS SHOULD  
REMAIN RELATIVELY LIGHT ACROSS MOST OF THE WFO PAH FORECAST AREA.  
 
ADJUSTED THE REGIONALLY BLENDED MODEL GUIDANCE FOR SENSIBLE  
WEATHER ELEMENTS TO INCLUDE A LITTLE MORE WEIGHTING FROM THE NAM-  
WRF MODEL FAMILIES, THE CANADIAN, AND GFS GUIDANCE.  
   
LONG TERM
 
(WEDNESDAY THROUGH SATURDAY)  
ISSUED AT 246 AM CDT SUN JUN 25 2017  
 
DECREASING CONFIDENCE IN THE EXTENDED AS A VERY UNSETTLED WEATHER  
PATTERN IS STARTING TO TAKE SHAPE.  
 
WE START OUT THE EXTENDED WITH FAIRLY HIGH CONFIDENCE WITH RESPECT  
TO TEMPERATURE...HUMIDITY AND LACK OF PRECIP. AFTER WEDNESDAY  
HOWEVER CONFIDENCE DECREASES MAINLY WITH PRECIP CHANCES AND DURATION  
OF PRECIP. AMOUNTS ARE STILL MEAGER SO MEDIUM CONFIDENCE WITH THAT  
PARAMETER. BY WEDNESDAY THE UPPER HIGH CONTINUES TO DRIFT OFF THE  
SOUTHEAST COAST OF THE US. WHILE THE FLOW ALOFT REMAINS NEAR ZONAL  
UNTIL FRIDAY AND SATURDAY WHEN A SUBTLE TROUGH ALOFT WILL ROTATE  
THROUGH THE AREA. THIS WILL BE OUR BEST CHANCE OF SIGNIFICANT  
RAINFALL. THERE IS ALSO A SURFACE COLD FRONT TO OUR NORTHWEST BUT AT  
THIS TIME IT DOES NOT APPEAR TO MAKE IT THROUGH THE AREA...AS IT  
APPEARS TO LOSE INTENSITY AND SOUTHWARD PROGRESS. HOWEVER WITH THE  
GULF WIDE OPEN FOR BUSINESS THIS WILL ALLOW FOR MOISTURE TO POOL  
OVER OUR AREA LATE THIS WEEK AND THROUGH THE WEEKEND. SO THERE WILL  
BE THUNDERSTORMS OVER THE AREA AT LEAST AT TIMES. MOST LIKELY DURING  
THE HEAT OF THE DAY BUT THERE IS ELEVATED INSTABILITY OVERNIGHT AS  
WELL. WIND SHEAR REMAIN FAIRLY UNIDIRECTIONAL THROUGH THE WEEKEND  
AND NOT ALL THAT STRONG WITH STRONGEST WINDS 25 KNOTS THROUGH MOST  
OF THE COLUMN FRIDAY. THEY DECREASE BUT REMAIN UNIDIRECTIONAL  
THROUGH THE WEEKEND. CAPES WILL RANGE FROM 2-3K J/KG DURING THE  
AFTERNOON HOURS THIS WEEKEND...BUT DECREASE TO 1K IN THE OVERNIGHT  
HOURS. IN ADDITION PW'S RANGE FROM ONE AND HALF TO BETTER THAN 2"  
INCHES. SO THEY WILL BE VERY EFFICIENT RAIN PRODUCERS WHERE EVER  
THEY FORM. A SEVERE STORM CANT BE RULED OUT TOWARD WEEKS  
END...WIDESPREAD SEVERE IS NOT ANTICIPATED AT THIS TIME. ALSO WITH  
FREEZING LEVELS 15K FEET AND HIGHER MOST ANY HAIL WILL MELT BEFORE  
REACHING THE SURFACE. FINALLY TRIMMED POPS BACK TO CHANCE CATEGORY  
FOR DAYS 6 AND 7.  
 

 
   
AVIATION
 
 
ISSUED AT 1150 PM CDT SAT JUN 24 2017  
 
THE FORECASTS ARE VFR FOR THE 06Z TAF PERIOD. THE PRIMARY CONCERN  
WILL BE NORTHWEST WINDS GUSTING UP TO AROUND 20KTS IN THE  
AFTERNOON.  
 

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

 
 

 
 
SHORT TERM...SMITH  
LONG TERM...KH  
AVIATION...DRS  
 
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