138  
FXUS61 KILN 201052  
AFDILN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE WILMINGTON OH  
552 AM EST MON NOV 20 2017  
   
SYNOPSIS
 
 
HIGH PRESSURE ACROSS THE OHIO VALLEY THIS MORNING WILL MOVE TO  
THE CAROLINAS THIS EVENING. A COLD FRONT WILL MOVE EAST INTO THE  
WESTERN GREAT LAKES TONIGHT, AND THEN ACROSS THE REMAINDER OF  
THE GREAT LAKES AND OHIO VALLEY TUESDAY INTO TUESDAY NIGHT. HIGH  
PRESSURE WILL RETURN TO THE REGION FOR WEDNESDAY AND THANKSGIVING  
DAY. TEMPERATURES NEAR NORMAL WILL DROP TO BELOW NORMAL  
READINGS FOR WEDNESDAY AND THANKSGIVING DAY.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
THE REGION WILL BE UNDER THE INFLUENCE OF A QUASI-ZONAL UPPER  
LEVEL FLOW TODAY. AT THE SURFACE, HIGH PRESSURE EXTENDING INTO  
THE OHIO VALLEY THIS MORNING WILL MOVE TOWARD THE CAROLINAS BY  
THIS EVENING. AN EMBEDDED DISTURBANCE WILL BRING SOME CIRRUS TO  
THE AREA, PROVIDING FILTERED SUNSHINE. THE PRESSURE GRADIENT  
WILL BE TIGHTEST ACROSS OUR NORTHWEST, RESULTING IN LOCAL  
SOUTHERLY WIND GUSTS IN THE 20 TO 25 KNOT RANGE. TEMPERATURES  
WILL WARM INTO THE MID AND UPPER 40S, WHICH IS NEAR OR SLIGHTLY  
BELOW NORMAL.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/
 
 
AS THE CENTER OF THE HIGH MOVES OFF THE CAROLINA COAST TONIGHT,  
A COLD FRONT WILL MOVE EAST INTO THE WESTERN GREAT LAKES. WE  
SHOULD SEE SOME CIRRUS OVERNIGHT, SOME FROM THE DEPARTING  
DISTURBANCE AND MORE AHEAD OF THE NEXT SYSTEM. WINDS WILL STAY  
UP WITH SOME LOCAL GUSTS DEVELOPING OVERNIGHT ACROSS THE  
NORTHWEST AS THE GRADIENT TIGHTENS WELL AHEAD OF THE COLD FRONT.  
LOWS WILL RANGE FROM THE LOWER TO MID 30S.  
 
ON TUESDAY, MID LEVEL S/WV WILL DIG SOUTHEAST INTO THE GREAT  
LAKES. AS THIS OCCURS, THE COLD FRONT WILL MOVE SOUTHEAST,  
ENTERING OUR NORTHWEST ZONES BY LATE IN THE DAY. MODELS HAVE  
TRENDED WETTER WITH THIS FRONT, SUCH THAT A CHANCE OF SHOWERS IS  
NOW IN THE FORECAST FOR THE NORTHWEST LATE TUESDAY AFTERNOON.  
CLOUDS WILL INCREASE FROM NORTHWEST TO SOUTHEAST THROUGHOUT THE  
DAY. IT WILL BE BREEZY WITH WIND GUSTS IN THE 20 TO 30 KNOT  
RANGE. HIGHS WILL RANGE FROM THE UPPER 40S NORTHWEST TO THE MID  
50S SOUTHEAST.  
 
FOR TUESDAY NIGHT, MID LEVEL S/WV IS EXPECTED TO PIVOT EAST  
ACROSS THE SOUTHERN GREAT LAKES, PUSHING THE COLD FRONT THROUGH  
OUR AREA. AGAIN, THE MODELS HAVE TRENDED WETTER, SO NOW HAVE A  
CHANCE OF SHOWERS FOR THE NORTHERN/EASTERN ZONES WHERE FORCING  
AND MOISTURE WILL BE THE GREATEST, TAPERING OFF TO A SLIGHT  
CHANCE ELSEWHERE. PRECIPITATION WILL OCCUR MOSTLY IN THE  
EVENING, DEPARTING BY EARLY MORNING. PARTIAL CLEARING IS  
EXPECTED OVERNIGHT WITH TEMPERATURES FALLING INTO THE UPPER 20S  
TO THE LOWER 30S BY MORNING.  
 

 
   
LONG TERM /WEDNESDAY THROUGH SUNDAY/
 
 
THE COLD FRONT WILL BE EAST OF THE AREA BY WEDNESDAY MORNING, WITH  
COLD ADVECTION OCCURRING ACROSS THE AREA, AS SURFACE HIGH PRESSURE  
BEGINS TO MOVE INTO THE REGION FROM THE MIDDLE MISSISSIPPI VALLEY  
REGION. AS THE DEPICTION OF THIS COLD FRONT HAS CONTINUED TO  
STRENGTHEN IN THE MODELS, SO HAS THE COLD AIR BEHIND IT, RESULTING  
IN A 10-15 DEGREE DROP IN MAX TEMPS FROM TUESDAY TO WEDNESDAY (A  
LITTLE MORE PRONOUNCED THAN IN PREVIOUS FORECASTS).  
 
A FAST (IF WAVY) NORTHERN STREAM WILL SET UP ACROSS THE NORTHERN  
CONUS / SOUTHERN TIER OF CANADA THROUGH THE REST OF THE EXTENDED  
FORECAST PERIOD. THE OHIO VALLEY WILL LARGELY REMAIN IN A REGIME OF  
WEAKER WESTERLY / NORTHWESTERLY FLOW TO THE SOUTH OF THE STRONGER  
JET, AT LEAST THROUGH THE REST OF THE WEEK, WITH SOME ADJUSTMENT AS  
A SHORTWAVE BUILDS SOUTHWARD ON SATURDAY.  
 
THERE HAS BEEN SOME CONSOLIDATION OF MODEL SOLUTIONS WITH REGARDS TO  
THIS WAVE, AND A COLD FRONT THAT WILL ALSO MOVE THROUGH THE REGION  
AT AROUND THE SAME TIME. WITH WARM ADVECTION FRIDAY NIGHT INTO  
SATURDAY MORNING (AND LIKELY NON-DIURNAL TEMPERATURES) CONDITIONS  
SHOULD BE WARM ENOUGH TO ALLOW FOR RAIN AS THE PRECIPITATION TYPE  
WHEN THE FRONT CROSSES THE AREA. NONETHELESS, WITH LIMITED MOISTURE  
(AS WILL BE THE CASE THROUGH THE ENTIRE EXTENDED FORECAST PERIOD)  
POPS WILL BE KEPT ON THE LOW END.  
 

 
   
AVIATION /12Z MONDAY THROUGH FRIDAY/
 
 
A RIDGE OF HIGH PRESSURE ACROSS THE OHIO VALLEY THIS MORNING  
WILL SHIFT SOUTHEAST THROUGH THE DAY. SOME HIGH CLOUDS WILL  
MOVE INTO THE AREA AS A WEAK DISTURBANCE ROTATES EAST. WINDS  
WILL BECOME SOUTH, WITH LOCAL GUSTS AROUND 20 KNOTS NEAR THE  
NORTHERN TERMINALS BETWEEN 16Z AND 22Z.  
 
FOR TONIGHT, WEAK DISTURBANCE MOVES EAST, BUT MORE HIGH LEVEL  
CLOUDS WILL APPROACH FROM THE NORTHWEST AS A MID LEVEL  
DISTURBANCE DROPS SOUTHEAST INTO THE UPPER MISSISSIPPI RIVER  
VALLEY/WESTERN GREAT LAKES. LOW PRESSURE AND A COLD FRONT WITH  
THIS FEATURE WILL BEGIN TIGHTENING THE SURFACE PRESSURE GRADIENT  
OVERNIGHT. ABOVE THE SURFACE, A FAIRLY DECENT LOW LEVEL JET WILL  
MOVE SOUTHEAST INTO THE REGION. THIS WILL BRING THE THREAT FOR  
NON-CONVECTIVE LLWS CONDITIONS, DEVELOPING BETWEEN 04Z AND 06Z.  
 
OUTLOOK...NO SIGNIFICANT WEATHER EXPECTED.  
 

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

 
 

 
SYNOPSIS...HICKMAN  
NEAR TERM...HICKMAN  
SHORT TERM...HICKMAN  
LONG TERM...HATZOS  
AVIATION...HICKMAN  
 
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