039  
FXUS61 KILN 200726  
AFDILN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE WILMINGTON OH  
326 AM EDT FRI APR 20 2018  
   
SYNOPSIS
 
 
HIGH PRESSURE OVER MINNESOTA AND IOWA WILL SHIFT EAST INTO THE  
GREAT LAKES AND OHIO VALLEY OVER THE NEXT FEW DAYS, BRINGING DRY  
WEATHER AND BELOW NORMAL TEMPERATURES. SOME FROST AND FREEZING  
TEMPERATURES WILL BE POSSIBLE AGAIN TONIGHT ESPECIALLY NORTH OF  
THE OHIO RIVER. THE HIGH WILL MOVE INTO NEW ENGLAND OVER THE  
WEEKEND AS LOW PRESSURE SLOWLY ORGANIZES OVER THE LOWER  
MISSISSIPPI RIVER VALLEY. THIS LOW PRESSURE SYSTEM WILL MOVE  
VERY SLOWLY NORTHEAST AND INCREASE THE THREAT OF RAIN ACROSS THE  
OHIO VALLEY MONDAY NIGHT AND TUESDAY AS TEMPERATURES REMAIN  
BELOW NORMAL.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
AMPLE SUNSHINE TODAY AS HEIGHT RISES/SHORTWAVE RIDGING DEVELOP  
ACROSS THE OHIO VALLEY, AND SURFACE HIGH PRESSURE BUILDS THROUGH  
THE GREAT LAKES AND OHIO VALLEY. YET ANOTHER DAY OF BELOW NORMAL  
TEMPERATURES ON TAP, THOUGH VERY DRY LOWER TROPOSPHERE WILL AID  
WARMING OF THE BOUNDARY LAYER WITH FULL SUN. MID-UPPER 50S FOR  
ALL WITH LIGHT NORTH/NORTHEAST WINDS AS THE HIGH DRIFTS BY TO  
THE NORTH, KEEPING WEAK LOW-LEVEL COLD ADVECTION ACROSS THE  
AREA. WILL ALLOW DEWPOINTS TO MIX OUT THIS AFTERNOON IN THIS  
FAVORABLE SETUP FOR AFTERNOON MOISTURE MIXING AS TYPICALLY  
OCCURS IN APRIL WITH NORTH/NORTHEAST BOUNDARY LAYER FLOW.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/
 
 
COLLABORATED THE NEED FOR ANOTHER SET OF FROST/FREEZE HEADLINES  
WITH ADJACENT OFFICES AND DETERMINED THERE'S ENOUGH UNCERTAINTY  
IN A FEW AREAS TO HOLD OFF FOR NOW, THOUGH FEEL PRETTY CERTAIN  
AT LEAST FROST ADVISORIES WILL BE NEEDED FOR THE SCIOTO VALLEY  
OF SOUTH-CENTRAL OHIO WESTWARD INTO PORTIONS OF SOUTHWEST OHIO.  
A WORST CASE SCENARIO ALLOWS FOR VERY STRONG RADIATIONAL COOLING  
WITH THE VERY DRY BOUNDARY LAYER TONIGHT, ALLOWING POTENTIAL FOR  
A FREEZE AGAIN IN THE SCIOTO VALLEY. HOWEVER, THERE ARE FEW  
CONCERNS: 1) CLEAR MODEL SIGNAL OF INCREASING CIRRUS/HIGH LEVEL  
CLOUDS AS THE NIGHT WEARS ON WHICH MAY BE ENOUGH TO KEEP THAT  
NEAR-SUNRISE TEMP PLUMMET FROM OCCURRING AND 2) A PERSISTENT BUT  
WEAK EASTERLY FLOW THAT MAINTAINS OVER THE AREA AS THE HIGH  
DRIFTS BY TO THE NORTH AND THEN NORTHEAST WHICH MAY BE ENOUGH  
TO KEEP FROST FROM BEING WIDESPREAD AND 3) THE VERY DRY BOUNDARY  
LAYER MAY NOT BE MOIST ENOUGH TO ALLOW FOR A HEAVIER FROST  
POTENTIAL. ADJACENT OFFICES WERE EITHER UNCERTAIN ON  
TEMPERATURES COLD ENOUGH FOR FROST, OR UNCERTAIN ON  
WIND/CLOUD/DRY BOUNDARY LAYER TO KEEP FROST FROM FORMING. SO  
WILL HOLD OFF ON NEW SET OF ADVISORIES/WARNINGS FOR RIGHT NOW,  
BUT CAN SEE THE SCIOTO VALLEY /AT A MINIMUM/ NEEDING SOME LEVEL  
OF MESSAGING TONIGHT AS THE BEST OVERLAP OF LIGHTER  
WINDS/COLDEST TEMPERATURES/THINNEST CIRRUS IS HERE. RAN WITH A  
CONSENSUS OF BIAS-CORRECTED STATISTICAL MOS FOR LOW TEMPS IN  
THIS STABLE TEMP REGIME.  
 
ON SATURDAY AND SATURDAY NIGHT, DEEP CLOSED LOW ACROSS KS/OK  
DRIFTS SLOWLY EAST/SOUTHEAST INTO THE LOWER MISSISSIPPI RIVER  
VALLEY. MID/HIGH LEVEL ISENTROPIC ASCENT TO BRING A THICKENING  
SHIELD OF MID/HIGH CLOUDS OVER THE AREA DURING THIS PERIOD /ESP  
NORTH OF THE OHIO RIVER/ WHILE LOW LEVEL FLOW REMAINS EXTREMELY  
DRY AND SOURCED FROM THE EAST. THIS WILL KEEP ANY PRECIPITATION  
TIED TO THE APPROACHING UPPER LOW PINNED VERY FAR TO THE WEST  
ACROSS THE MID MISSISSIPPI RIVER VALLEY, AND MORE BELOW NORMAL  
TEMPERATURES ON THE COOL EASTERLY FLOW.  
 

 
   
LONG TERM /SUNDAY THROUGH THURSDAY/
 
 
SURFACE HIGH PRESSURE OVER THE EASTERN GREAT LAKES WILL SHIFT OFF TO  
THE EAST THROUGH THE DAY ON SUNDAY. MEANWHILE, A CLOSED 500 MB LOW  
OVER THE SOUTHERN MISSISSIPPI VALLEY WILL DRIFT SLOWLY EAST THROUGH  
THE DAY ON SUNDAY BEFORE LIFTING NORTHEAST ACROSS THE TENNESSEE  
VALLEY AND OPENING UP MONDAY INTO TUESDAY.  
 
THERE ARE SOME MODEL DIFFERENCES WITH THE NORTHWARD EXTENT OF THE  
PCPN SHIELD ASSOCIATED WITH THIS WITH THE 00Z GFS SOMEWHAT FARTHER  
NORTH THAN THE 00Z ECMWF AND CMC. HOWEVER, THE 00Z GEFS IS SOMEWHAT  
MORE IN LINE WITH KEEPING THINGS A BIT FARTHER SOUTH SO WILL TREND  
FORECAST ACCORDINGLY. WITH THIS IN MIND, WILL ALLOW FOR SOME LOWER  
CHANCE POPS TO WORK INTO OUR SOUTHERN AREAS THROUGH MONDAY  
AFTERNOON. WILL THEN GRADUALLY OVERSPREAD THE REMAINDER OF THE AREA  
WITH SLIGHT CHANCE TO CHANCE POPS MONDAY NIGHT INTO TUESDAY WITH THE  
HIGHEST POPS BEING ACROSS OUR SOUTHEAST.  
 
THE GFS IS A BIT MORE IMPRESSIVE THAN THE ECMWF WITH SOME ADDITIONAL  
MID LEVEL ENERGY DROPPING DOWN FROM THE NORTHWEST WEDNESDAY INTO  
THURSDAY. EITHER WAY THOUGH, IT LOOKS LIKE THIS WILL BE ENOUGH TO  
LINGER AT LEAST A CHANCE OF SHOWERS ACROSS THE AREA THROUGH MID  
WEEK.  
 
DAYTIME TEMPERATURES WILL REMAIN NEAR OR SLIGHTLY BELOW NORMAL  
THROUGH THE LONG TERM PERIOD. HIGHS WILL GENERALLY BE IN THE LOW TO  
MID 60S WHILE OVERNIGHT LOWS WILL BE MAINLY IN THE 40S.  
 

 
   
AVIATION /07Z FRIDAY THROUGH TUESDAY/
 
 
VFR CONDITIONS ACROSS THE TERMINALS THROUGH THE NEXT 24 HOURS.  
CLEAR SKIES EXPECTED TO DOMINATE WITH PERHAPS A LITTLE SCT-BKN  
CIRRUS LATER FRIDAY NIGHT DRIFTING IN FROM THE NORTHWEST. WINDS  
WILL BE LIGHT FROM THE NORTH THROUGH SUNRISE THIS MORNING,  
BEFORE TURNING NORTHEAST ESPECIALLY AT CVG/LUK/ILN WHILE CMH/LCK  
WILL TEND TO STAY MORE NORTHERLY DURING THE DAY DUE TO THE PATH  
OF HIGH PRESSURE ACROSS NORTHERN OHIO/INDIANA.  
 
OUTLOOK...MVFR CEILINGS POSSIBLE ON MONDAY INTO TUESDAY.  
 

 
   
ILN WATCHES/WARNINGS/ADVISORIES
 
 
OH...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR OHZ060>065-  
070>074-077>082-088.  
KY...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR KYZ089>100.  
IN...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR INZ050-058-059-  
066-073>075-080.  
 

 
 

 
SYNOPSIS...BINAU  
NEAR TERM...BINAU  
SHORT TERM...BINAU  
LONG TERM...JGL  
AVIATION...BINAU  
 
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