839  
FXUS61 KILN 200855  
AFDILN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE WILMINGTON OH  
355 AM EST THU FEB 20 2020  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL BUILD INTO THE AREA TODAY THROUGH FRIDAY AND  
THEN PERSIST THROUGH THE WEEKEND. THE NEXT PRECIPITATION WILL  
NOT SPREAD INTO THE REGION UNTIL MONDAY AHEAD OF THE A STORM  
SYSTEM.  
 

 
   
NEAR TERM /UNTIL 6 AM THIS MORNING/
 
 
EXTENSIVE HIGH AND MID CLOUDS ASSOCIATED WITH A JET STREAK WILL  
CONTINUE TO MOVE ACROSS THE AREA THIS MORNING. THESE CLOUDS WILL  
CLEAR IN THE AFTERNOON AS THE JET STREAK HEADS EAST. BUT THE  
INCREASE IN INSOLATION MAY RESULT IN SOME STRATOCUMULUS  
DEVELOPING. HIGHS WILL BE OVER 10 DEGREES BELOW NORMAL. NORTH  
WINDS WILL INCREASE A BIT THIS AFTERNOON AND WIND CHILLS WILL  
GET NO HIGH THAN THE LOWER 20S.  
 

 
   
SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/
 
 
POSITIVELY TILTED MID LEVEL TROUGH WILL PASS ACROSS THE AREA  
TONIGHT FOLLOWED BY NORTHWEST FLOW. MEANWHILE HIGH PRESSURE AT  
THE SURFACE WILL BUILD INTO THE REGION. AIRMASS WILL BE COLD  
AND VERY DRY WITH LITTLE IF ANY CLOUD COVER. TEMPERATURES WILL  
GENERALLY DROP INTO THE MID TEENS TONIGHT. READINGS WILL REBOUND  
A BIT ON FRIDAY BUT STILL BE WELL BELOW NORMAL.  
 

 
   
LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/
 
 
ON FRIDAY NIGHT, THE CENTER OF A LARGE AREA OF SURFACE HIGH PRESSURE  
WILL BE LOCATED OVER WESTERN TENNESSEE. THIS HIGH WILL COVER A LARGE  
EXPANSE OF REAL ESTATE, FROM THE LOWER MISSISSIPPI VALLEY THROUGH  
THE GREAT LAKES, AND AS FAR EAST AS THE VIRGINIA COAST. THE HIGH  
WILL ALSO BRING AN ESPECIALLY DRY AIR MASS, WITH PRECIPITABLE WATER  
VALUES OVER THE ILN FORECAST AREA OF AROUND A TENTH OF AN INCH. AS  
THE HIGH GRADUALLY DRIFTS EAST OVER THE WEEKEND, WINDS WILL SHIFT  
AROUND TO THE SOUTH, BRINGING A WARMING TREND THROUGH THE FIRST FEW  
DAYS OF THE EXTENDED FORECAST PERIOD. THIS WILL BEGIN AFTER ANOTHER  
COOL NIGHT ON FRIDAY NIGHT INTO SATURDAY MORNING, WITH MIN  
TEMPERATURES AROUND 20 DEGREES. AFTER THAT, WARM ADVECTION IN SUCH A  
DRY AIR MASS WILL SEE TEMPERATURES RISE AS MUCH AS 25 TO POSSIBLY 30  
DEGREES, WITH DAYTIME MAX TEMPS ON SATURDAY IN THE MIDDLE TO UPPER  
40S.  
 
AFTER ANOTHER DAY OF WARMING ON SUNDAY, ATTENTION WILL TURN TO  
UPSTREAM CYCLOGENESIS, AS A TROUGH MOVING OUT OF THE FOUR CORNERS  
AREA IS EXPECTED TO DEVELOP A SURFACE LOW OVER THE TX/OK PANHANDLE  
AREA BY SUNDAY EVENING. AS THIS TROUGH MOVES EAST ON MONDAY, IT IS  
GENERALLY EXPECTED TO WEAKEN, MOVING MORE QUICKLY AS IT PASSES  
THROUGH THE OHIO VALLEY ON MONDAY AND MONDAY NIGHT. OVERALL MODEL  
AGREEMENT (AND THUS FORECAST CONFIDENCE) IS FAIR WITH REGARD TO THE  
SYSTEM OVERALL, BUT SPECIFICS ON THE SURFACE LOW TRACK AND SPEED OF  
THE TROUGH ARE OF SLIGHTLY LOWER CONFIDENCE. IT IS IN THIS PERIOD OF  
THE FORECAST (SUNDAY NIGHT INTO MONDAY EVENING) WHERE GEFS SPREAD  
INCREASES SIGNIFICANTLY, SUGGESTING THAT THE DETAILS REMAIN FUZZY  
WITH REGARDS TO HOW THIS SYSTEM IS GOING TO BEHAVE. WHAT DOES LOOK  
LIKELY IS THAT IT WILL BE PRIMARILY AN ISSUE OF RAIN, AS  
TEMPERATURES WILL BE TOO WARM FOR MUCH (IF ANY) SNOW MIXING IN AT  
THE BEGINNING, AND ONLY COOLING DOWN ENOUGH FOR SNOW AT THE END OF  
THE EVENT AFTER THE STRONGER FORCING HAS DEPARTED. NON-DIURNAL  
TEMPERATURES ALSO APPEAR LIKELY, PARTICULARLY MONDAY NIGHT -- WITH  
WARM ADVECTION CONTINUING UNTIL THE SURFACE LOW HAS PASSED THROUGH  
THE AREA. OVERALL, THIS DOES NOT APPEAR LIKELY TO BE A PARTICULARLY  
IMPACTFUL SYSTEM FOR THE ILN CWA, BUT AS MENTIONED, THE SPECIFICS  
ARE STILL SOMEWHAT UNCLEAR AT THIS DISTANCE IN THE FORECAST.  
 
BEYOND MONDAY NIGHT, IT APPEARS THAT THE NEXT CHANCE FOR  
PRECIPITATION WILL COME ON TUESDAY NIGHT INTO WEDNESDAY, AS ANOTHER  
TROUGH ROTATES SOUTHEAST THROUGH THE UPPER MIDWEST AND GREAT LAKES  
REGIONS. AT THIS POINT, TEMPERATURES WILL BE COOLER, WITH COLD  
ADVECTION EXPECTED BEHIND THE MONDAY SYSTEM. THUS, THERE MAY BE A  
CHANCE FOR SOME SNOW TO MIX IN AT SOME POINT BY THE MIDDLE OF NEXT  
WEEK.  
 

 
   
AVIATION /09Z THURSDAY THROUGH MONDAY/
 
 
VFR WILL PREVAIL THROUGH THE PERIOD. HIGH AND MID CLOUDS WILL  
STREAM ACROSS THE REGION AND THEN CLEAR FROM NORTHWEST TO  
SOUTHEAST AFTER 18Z. BUT SOME SCATTERED STRATOCUMULUS MAY  
DEVELOP ONCE THESE HIGHER CLOUDS MOVE OUT. SKIES WILL CLEAR BY  
00Z. NORTHERLY WINDS WILL INCREASE TO 10 TO 15 KT DURING THE DAY  
AND THEN SLOWLY DIMINISH LATE IN THE PERIOD.  
 
OUTLOOK...MVFR CEILINGS AND VISIBILITIES POSSIBLE ON MONDAY.  
 

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

 
 

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