894  
FXUS63 KPAH 261935  
AFDPAH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PADUCAH KY  
235 PM CDT WED JUL 26 2017  
   
SHORT TERM
 
(TONIGHT THROUGH FRIDAY NIGHT)  
ISSUED AT 234 PM CDT WED JUL 26 2017  
 
THE MAIN FORECAST ISSUE IS CONVECTION ASSOCIATED WITH A STRONG  
COLD FRONT THAT WILL CROSS OUR REGION THURSDAY NIGHT/FRIDAY  
MORNING. THE TIMING AND LOCATION OF STORMS WILL BE INFLUENCED BY  
MESOSCALE FEATURES THAT EVEN THE HIGH-RES MODELS ARE NOT IN  
AGREEMENT ON.  
 
IN THE NEAR TERM, ISOLATED STORMS HAVE DEVELOPED IN A VERY MOIST  
AND UNSTABLE ENVIRONMENT THIS AFTERNOON ACROSS SOUTHERN IL, SW  
INDIANA, AND NW KENTUCKY. HEAT INDICES IN THE 105 TO 110 RANGE  
HAVE BEEN WIDESPREAD THIS AFTERNOON, AND THE HEAT ADVISORY WILL  
CONTINUE INTO THIS EVENING.  
 
THE ISOLATED ACTIVITY THIS EVENING MAY THEN GIVE WAY TO A MORE  
WIDESPREAD PERIOD OF THUNDERSTORMS OVERNIGHT, MAINLY ALONG AND  
NORTH OF A KMDH-KOWB LINE. A 500 MB SHORTWAVE OVER IOWA AT THIS  
TIME WILL MOVE EASTWARD INTO INDIANA OVERNIGHT. THIS SHORTWAVE MAY  
PROVIDE ENOUGH UPPER-LEVEL SUPPORT TO INDUCE NEW CONVECTION ALONG  
OUTFLOW BOUNDARIES GENERATED BY THE ONGOING STORMS OVER SOUTHERN  
IL OR THE MORNING MCS THAT IS DECAYING OVER MISSOURI. THE 12Z NAM  
IS ONE OF SEVERAL HIGH-RES MODELS THAT FOLLOW THIS IDEA.  
THEREFORE, POPS WILL BE IN THE LIKELY CATEGORY OVERNIGHT ALONG  
I-64. HEAVY RAIN APPEARS TO BE THE PRIMARY HAZARD DUE TO THE  
EXCESSIVE MOISTURE CONTENT OF THE ATMOSPHERE.  
 
ON THURSDAY, THE TIMING AND COVERAGE OF STORMS BECOMES VERY  
MUDDLED. WHILE THE MODELS ALL GENERATE QPF, THE PLACEMENT AND  
AMOUNTS ARE VERY RANDOM. ONE POSSIBILITY IS THAT THE POTENTIAL  
OVERNIGHT MCS WILL LAY OUT A BOUNDARY ACROSS WESTERN KY AND SE  
MISSOURI. THIS BOUNDARY WOULD THEN BECOME ACTIVE DURING THE  
AFTERNOON. THE FORECAST BASICALLY FOLLOWS THIS THINKING, WITH  
HIGHS TEMPS RANGING FROM THE LOWER 80S ALONG THE WHITE RIVER OF  
INDIANA TO THE LOWER 90S ALONG THE ARKANSAS BORDER. HEAT INDICES  
COULD AGAIN BE A CONCERN ALONG AND SOUTH OF A KCGI-KPAH-KHOP LINE,  
BUT THERE IS TOO MUCH MODEL VARIABILITY TO WARRANT ANY HEADLINES.  
 
THURSDAY NIGHT, THE COLD FRONT WILL MOVE SOUTHEAST INTO THE LOWER  
OHIO VALLEY. THE GFS REMAINS QUITE A BIT SLOWER THAN MOST OTHER  
GUIDANCE. THE OFFICIAL FORECAST FOLLOWS A FASTER CONSENSUS BLEND,  
BUT IN REALITY MESOSCALE OUTFLOW BOUNDARIES WILL LIKELY MAKE THE  
FRONT DIFFICULT TO LOCATE. SHOWERS AND STORMS WILL BE LIKELY THURS  
NIGHT AS A STRONG 500 MB SHORTWAVE DROPS SOUTHEAST ACROSS THE  
GREAT LAKES REGION. AGAIN, HEAVY RAINFALL WILL BE A CONCERN DUE TO  
HIGH PRECIP WATER VALUES. SEVERE WEATHER POTENTIAL MAY BE LIMITED  
BY POOR AIR MASS RECOVERY IN THE WAKE OF OUTFLOW BOUNDARIES FROM  
MULTIPLE ROUNDS OF STORMS. THE CONVECTION SHOULD WIND DOWN  
FRIDAY AS THE FRONT EXITS OUR REGION IN THE MORNING.  
 
THE COOLER AND DRIER AIR WILL BE SLOW TO FILTER SOUTHWARD ON  
FRIDAY, HOWEVER THE DIFFERENCE SHOULD BECOME NOTICEABLE FRIDAY  
NIGHT AS DEW POINTS FALL THROUGH THE 60S.  
   
LONG TERM
 
(SATURDAY THROUGH WEDNESDAY)  
ISSUED AT 234 PM CDT WED JUL 26 2017  
 
ABOVE AVERAGE CONFIDENCE IN THE EXTENDED PERIOD WITH A WELCOME  
PATTERN CHANGE TO COOLER, LESS HUMID CONDITIONS. LITTLE, IF ANY,  
PRECIPITATION IS EXPECTED THROUGH MID NEXT WEEK.  
 
AT 12Z SATURDAY, SURFACE HIGH PRESSURE WILL BE CENTERED OVER THE  
GREAT LAKES REGION, HELPING TO USHER IN A DRIER AND COOLER AIRMASS  
ON NORTHEAST WINDS. VERY LITTLE MOVEMENT IN THIS HIGH PRESSURE IS  
EXPECTED INTO EARLY NEXT WEEK. AS FAR AS THE OVERALL UPPER LEVEL  
SYNOPTIC PATTERN GOES, RIDGING WILL BE CENTERED OVER THE WESTERN  
U.S. WITH TROUGHING OVER THE EAST. OUR AREA WILL BE DOMINATED BY  
NORTHWEST FLOW ALOFT.  
 
DRY CONDITIONS WILL BE IN PLACE THIS WEEKEND INTO MONDAY. SOME  
GUIDANCE IS HINTING AT SOME DIURNAL CONVECTION AS EARLY AS TUESDAY  
AFTERNOON, BUT THE CONFIDENCE IN THIS IS TOO LOW TO HAVE MENTIONABLE  
POPS. BY WEDNESDAY, CHANCES APPEAR A BIT BETTER REGARDING DIURNAL  
ACTIVITY, AND THUS HAVE SOME SLIGHT POPS FOR THIS PERIOD.  
 
TEMPERATURES WILL BE BELOW NORMAL THIS WEEKEND, GRADUALLY RISING  
CLOSER TO NORMAL BY TUESDAY AND WEDNESDAY AS UPPER LEVEL HEIGHTS  
RISE SLIGHTLY. WITH HIGHS IN THE LOW TO MID 80S ALONG WITH LOWER  
HUMIDITY LEVELS, IT WILL BE A VERY PLEASANT LATE JULY WEEKEND.  
DEWPOINTS ARE FORECAST TO DROP AT LEAST INTO THE UPPER 50S TO LOWER  
60S AREA WIDE, AND QUITE POSSIBLY INTO THE MID 50S IN SOME LOCALES.  
THESE VALUES WILL BE NEAR OR BELOW THE 5TH PERCENTILE AS FAR AS  
TYPICAL LATE JULY DEWPOINTS GO. MORNING LOW TEMPERATURES WILL DROP  
INTO THE UPPER 50S TO LOWER 60S FOR A COUPLE NIGHTS, PROVIDING AN  
ALMOST EARLY FALL-LIKE FEEL TO THE AIR. A GRADUAL RISE IN HUMIDITY  
LEVELS IS EXPECTED NEXT WEEK, BUT IT APPEARS WE SHOULD KEEP  
DEWPOINTS BELOW 70 THROUGH TUESDAY, AND POSSIBLY INTO WEDNESDAY FOR  
MUCH OF THE REGION. OVERALL, WE CAN'T ASK FOR MUCH BETTER WEATHER TO  
CLOSE OUT JULY!  
 

 
   
AVIATION
 
 
ISSUED AT 1241 PM CDT WED JUL 26 2017  
 
ISOLATED SHOWERS AND STORMS WERE JUST STARTING TO POP UP AT NOON  
TODAY. MOST OF THE ACTIVITY THIS AFTERNOON IS FORECAST TO OCCUR  
NEAR A WEAK FRONT THAT EXTENDS FROM THE KOWB AREA NORTHWEST ACROSS  
KEVV. THE MENTION OF VCTS WAS CONTINUED IN THE KEVV/KOWB TAFS FOR  
THIS AFTERNOON. OTHERWISE, EXPECT MAINLY SCATTERED CUMULUS CLOUDS  
BASED AROUND 4 TO 5K FEET.  
 
THE CUMULUS CLOUDS WILL DISSIPATE AROUND SUNSET. SOUTHWEST WINDS  
WILL REMAIN STRONG ENOUGH TO INHIBIT FOG TONIGHT. VFR CONDITIONS  
WILL PERSIST THROUGH THURSDAY MORNING.  
 

 
   
PAH WATCHES/WARNINGS/ADVISORIES
 
 
IL...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR ILZ075-080>082-  
084>094.  
 
MO...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR MOZ076-086-087-100-  
107>112-114.  
 
IN...NONE.  
KY...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR KYZ001>013.  
 

 
 

 
 
SHORT TERM...MY  
LONG TERM...SP  
AVIATION...MY  
 
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