736  
FXUS61 KILN 220013  
AFDILN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE WILMINGTON OH  
813 PM EDT SAT OCT 21 2017  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL SHIFT OFF TO THE EAST THROUGH THE DAY ON  
SUNDAY, PROVIDING FOR ONE LAST DAY OF DRY CONDITIONS AND ABOVE  
NORMAL CONDITIONS. AN UPPER LEVEL DISTURBANCE AND AN ASSOCIATED  
COLD FRONT WILL BRING AN INCREASING CHANCE OF SHOWERS SUNDAY  
NIGHT INTO MONDAY. THIS WILL ALSO USHER IN A COOLER AIRMASS  
FOR NEXT WEEK.  
 

 
   
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
 
 
WHILE HIGH CLOUDS CONTINUING TO PUSH THROUGH THE REGION, STILL  
PLENTY OF GAPS IN CLOUDS AND WINDS SLACKENING A LITTLE MORE, SO  
HAVE NUDGED OVERNIGHT LOWS JUST SLIGHTLY LOWER, IN ESPECIALLY  
THE EASTERN AREA WHERE APPROACHING TROUGH AXIS AND THE  
TIGHTENING GRADIENT WILL KEEP WINDS LIGHTER OVERNIGHT. STILL  
GENERALLY MID 50S FOR LOWS, BUT NEAR 50 EAST.  
 

 
   
SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/
 
 
THE MID LEVEL TROUGH AXIS WILL SHIFT EAST OUT OF THE  
MISSISSIPPI VALLEY AND INTO THE LOWER OHIO VALLEY SUNDAY INTO  
SUNDAY NIGHT. AS IT DOES, SHORT WAVE ENERGY ROTATING THROUGH THE  
BASE OF THE TROUGH WILL LEAD TO A DEVELOPING SURFACE WAVE/LOW  
THAT WILL APPROACH OUR AREA LATE SUNDAY NIGHT. THE 12Z MODELS  
HAVE TRENDED A LITTLE FASTER WITH THIS SO HAVE SPED UP PCPN  
ONSET A FEW HOURS FOR SUNDAY NIGHT, ESPECIALLY ACROSS OUR  
SOUTHWEST.  
 
HIGHS ON SUNDAY WILL BE SOMEWHAT DEPENDENT ON CLOUD COVER, BUT  
IN CONTINUED SOUTHERLY FLOW, HIGHS SHOULD STILL PUSH WELL INTO  
THE 70S. LOWS SUNDAY NIGHT WILL BE IN THE UPPER 50S TO LOWER  
60S.  
 

 
   
LONG TERM /MONDAY THROUGH SATURDAY/
 
 
THE LONG TERM WILL OPEN UP WITH A PATTERN CHANGE TAKING PLACE AS A  
SURFACE LOW APPROACHES THE CWA FROM THE SOUTHWEST. THE PATTERN WILL  
BE RATHER COMPLEX WITH A POTENT UPPER LEVEL LOW EJECTING NORTHEAST  
OVER KENTUCKY AS IT TAKES ON A NEGATIVE TILT. AT THE SAME TIME AN  
UPPER LEVEL TROUGH AXIS WILL BE LOCATED OVER THE CENTRAL UNITED  
STATES. DURING THE DAY MONDAY THE UPPER LEVEL LOW WILL MOVE OVERHEAD  
ALONG WITH A WEDGE OF PVA. PWATS WITH THE LOW ARE EXPECTED TO SURGE  
TO AROUND 1.50" ACROSS THE AREA OR NEAR RECORD VALUES FOR THIS TIME  
OF YEAR. EVEN THOUGH INSTABILITY IS LACKING MONDAY IT SHOULD BE  
NOTED THAT LOW LEVEL SHEAR VALUES ARE EXTREMELY IMPRESSIVE. SFC TO 1  
KM BULK SHEAR IS NEARING 45 KTS ACROSS THE SOUTHEAST. WE WILL  
CONTINUE TO WATCH THIS TO SEE IF ANY INSTABILITY CAN WORK ITS WAY  
NORTH. THE OTHER CONCERN WITH THIS SYSTEM WILL BE THE POTENTIAL FOR  
HEAVY RAIN. FOR NOW, MOST MODEL TOTALS REMAIN IN THE ONE TO TWO INCH  
RANGE (ESP. ACROSS THE SOUTH AND EAST). CONFIDENCE ON RAINFALL  
TOTALS STILL REMAINS LOW THOUGH AS MOST GEFS MEMBERS INDICATE AROUND  
ONE INCH.  
 
MONDAY NIGHT INTO TUESDAY THE SURFACE LOW WILL EXIT EAST WITH A WEAK  
COLD FRONT PUSHING THROUGH. THE MAIN UPPER LEVEL THROUGH AXIS THAT  
WAS TO OUR NORTHWEST MONDAY AFTERNOON WILL BEGIN TO DEEPEN AND HEAD  
SOUTHEAST TOWARDS THE ILN FORECAST AREA TUESDAY MORNING. AS THIS  
OCCURS 850 MB TEMPERATURES WILL START TO DROP WITH HIGHS NOT EVEN  
EXPECTED TO REACH 60 DEGREES TUESDAY. IN FACT, MONDAY LOOKS LIKE THE  
WARMEST DAY OF THE EXTENDED. DURING THE DAY TUESDAY THE UPPER LEVEL  
LOW WILL THEN MOVE OVERHEAD. AS THE CORE OF THE UPPER LEVEL SYSTEM  
MOVES OVERHEAD 850 MB TEMPERATURES WILL SLOWLY DROP BELOW 0 DEGREES  
C ACROSS THE WESTERN ZONES. DUE TO THE UPPER LEVEL LOW AND  
STEEPENING LOW LEVEL LAPSE RATES HAVE KEPT THE CHANCE OF  
PRECIPITATION IN TUESDAY.  
 
WEDNESDAY THE UPPER LEVEL LOW WILL TAKE ITS TIME TO EXIT THE AREA  
ALLOWING THE CHANCE OF SHOWERS TO CONTINUE ACROSS OUR EASTERN ZONES.  
BY THURSDAY MORNING THE UPPER LEVEL LOW WILL BE EXITING EAST WITH  
THE BEST AGEOSTROPHIC CONVERGENCE OVERHEAD. AS THIS HAPPENS WEAK  
SURFACE HIGH PRESSURE WILL TEMPORARILY MOVE OVERHEAD WITH WINDS  
GOING CALM. TEMPORARY CLEARING IS ALSO SCHEDULED TO TAKE PLACE WHICH  
WILL MAKE TEMPERATURES IN THE MID 30S POSSIBLE THURSDAY MORNING  
(MAYBE A FREEZE EVEN IF THINGS LINE UP RIGHT).  
 
THURSDAY THE UPPER LEVEL LOW WILL EJECT EAST WITH MID LEVEL HEIGHTS  
TEMPORARILY RISING IN THE AFTERNOON. 850 MB TEMPERATURES ALSO  
BRIEFLY RISE TO AROUND 8 DEGREES C, BUT LOOKING AT THE GEFS AND EPS  
THINKING IS THAT HIGH TEMPERATURES WILL PROBABLY BE IN THE UPPER 50S  
TO AROUND 60 DEGREES THURSDAY. FRIDAY THOUGH SUNDAY ANOTHER UPPER  
LEVEL LOW WILL DEEPEN ACROSS MIDWEST CANADA AS HEIGHTS RISE OFF THE  
PACIFIC NORTHWEST COAST. 850 MB TEMPERATURES BEHIND THIS SYSTEM FALL  
TO AROUND 7 DEGREES C BELOW ZERO. TIMING REMAINS HIGHLY VARIABLE  
HERE THOUGH SO HAVE ONLY TRENDED TEMPERATURES DOWN AT THIS TIME.  
 

 
   
AVIATION /00Z SUNDAY THROUGH THURSDAY/
 
 
AS THE AREA BECOMES LESS DOMINATED BY THE UPPER RIDGE PUSHING  
EAST AND A TROUGH APPROACHES FROM THE MID MISSISSIPPI VALLEY,  
SOME INCREASED HIGH AND MID CLOUDS, BUT NEARLY ALL VFR EXPECTED  
THROUGH THE PERIOD. CONTINUED WITH SOME POTENTIAL FOR MVFR  
VISIBILITY AT KLUK, AS WHILE THERE SHOULD BE SLIGHTLY MORE WIND  
TONIGHT, PLENTY OF BREAKS IN THE MID AND HIGH CLOUDS MAY YIELD  
AN 08-12Z PERIOD OF MVFR.  
 
OUTLOOK...MVFR CEILINGS AND VISIBILITIES POSSIBLE SUNDAY NIGHT  
THROUGH WEDNESDAY.  
 

 
   
ILN WATCHES/WARNINGS/ADVISORIES
 
 
OH...NONE.  
KY...NONE.  
IN...NONE.  
 

 
 

 
SYNOPSIS...JGL  
NEAR TERM...JDR  
SHORT TERM...JGL  
LONG TERM...HAINES  
AVIATION...JDR  
 
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