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Area Forecast Discussion
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000
FXUS61 KILN 301748
AFDILN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
148 PM EDT THU OCT 30 2014

.SYNOPSIS...
HIGH PRESSURE WILL CONTROL THE WEATHER OVER THE OHIO VALLEY 
TODAY WITH DRY AND COOL CONDITIONS EXPECTED. A TROUGH OF LOW
PRESSURE AND A COLD FRONT WILL MOVE SOUTHEAST INTO THE REGION ON
FRIDAY BRINGING OCCASIONAL RAIN...WHICH MAY MIX WITH LIGHT SNOW
EARLY SATURDAY MORNING. MUCH COLDER CONDITIONS ARE EXPECTED BEHIND
THE COLD FRONT FOR THE WEEKEND WITH A WARMING TREND BEGINNING
EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EXTENSIVE STRATOCUMULUS ACROSS MUCH OF THE AREA HAS BEEN ERODING
FROM THE SOUTHWEST AND SHOULD CONTINUE TO GRADUALLY DO SO THROUGH
THE AFTERNOON ALTHOUGH IT WILL LIKELY NOT MAKE IT INTO CENTRAL
OHIO. LITTLE TO NO CHANGE TO FORECAST HIGHS. 

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
THE SHORT TERM FORECAST PERIOD WILL BE DOMINATED BY A COMPLEX
WEATHER SYSTEM THAT WILL AFFECT MUCH OF THE EASTERN PART OF THE
COUNTRY. A SHARP MID-LEVEL TROUGH IS EXPECTED TO DEVELOP
INTO A COMPACT CLOSED LOW AS IT MOVES SSE OUT OF THE CANADIAN
PLAINS...CROSSING THE WESTERN GREAT LAKES ON FRIDAY...AND REACHING
THE SOUTHEASTERN STATES ON SATURDAY MORNING. THE STRENGTH OF THIS
SYSTEM (AS NOTED BY HEIGHT ANOMALIES) IS VERY MUCH OUT OF THE
ORDINARY...AND AS ADMITTED BY NWS WPC...THIS LEADS TO SOME
CONFIDENCE CONCERNS IN THE OVERALL FORECAST FOR THE NEXT FEW DAYS.
OVERALL...THE IMPACTS FOR THE ILN FORECAST AREA WILL BE MOST
NOTABLE IN TERMS OF THE COLD TEMPERATURES MOVING INTO THE
AREA...WITH A FEW INTERESTING NOTES IN TERMS OF WINDS AND LIGHT
SNOW BEHIND THE SURFACE COLD FRONT.

A BRIEF PERIOD OF SOUTHWESTERLY FLOW WILL HELP KEEP TEMPERATURES
STEADY HEADED INTO FRIDAY MORNING...IN ADVANCE OF A SURFACE COLD
FRONT. THIS FRONT IS FORECAST TO MOVE SOUTHEAST THROUGH THE ILN
CWA DURING THE DAY ON FRIDAY. THIS REQUIRED A NON-DIURNAL
TEMPERATURE CURVE...WITH A GRADIENT IN MAX TEMPERATURES FROM
NORTHWEST TO SOUTHEAST. THE FRONT IS NOT EXPECTED TO BE A
SIGNIFICANT FOCUS FOR PRECIPITATION ON ITS OWN...BUT A LARGE AREA
FAVORABLE FOR ASCENT WILL BE LOCATED AHEAD (EAST) OF THE MID-LEVEL
LOW...ESPECIALLY AS A REGION OF UPPER DIVERGENCE MOVES THROUGH
LATE FRIDAY AFTERNOON INTO THE EVENING. ADDITIONAL PRECIPITATION
FROM A WEAK SHORTWAVE CROSSING THE LOWER OHIO VALLEY WILL
EVENTUALLY WRAP INTO THE MAIN DEEPENING TROUGH BY FRIDAY
AFTERNOON. FOCUSING ON THE AFTERNOON TO EARLY EVENING
PERIOD...LIKELY POPS HAVE BEEN INCLUDED FOR THE ENTIRE FORECAST
AREA...WITH THE GREATEST CHANCES (WHERE THERE WAS SERIOUS
CONSIDERATION FOR CATEGORICAL POPS) IN THE EASTERN HALF OF THE
CWA. A VERY SMALL AMOUNT OF INSTABILITY MAY ALLOW FOR A FEW
CONVECTIVE SHOWERS IN SOUTHERN OHIO AND NORTHEAST KENTUCKY ON
FRIDAY AFTERNOON...BUT BUFKIT SOUNDINGS SUGGEST EQUILIBRIUM LEVELS
OF ONLY AROUND -5C...NOT TALL ENOUGH FOR THUNDER.

THOUGH MODEL AGREEMENT IN THE GENERAL SETUP IS FAIRLY
STRONG...THE SPEED OF THE DEPARTURE OF PRECIPITATION EARLY
SATURDAY MORNING IS AN IMPORTANT QUESTION THAT REMAINS SOMEWHAT
UNCERTAIN. SEEING NO STRONG REASON TO MAKE A BIG CHANGE...THIS
FORECAST WILL STICK MAINLY TO CONTINUITY...WITH SIMILAR TIMING TO
THE PREVIOUS FORECAST. THIS WILL ALLOW FOR DRY CONDITIONS IN THE
WESTERN CWA BY 12Z SATURDAY...AND CLEARING OUT OF THE SCIOTO
VALLEY AFTER 18Z.

THE TEMPERATURE FORECAST FOR EARLY SATURDAY MORNING IS GOING TO BE
VERY CLOSELY TIED WITH THE POTENTIAL FOR SNOW. AS TEMPERATURES
CONTINUE TO COOL BEHIND THE SURFACE FRONT ON FRIDAY NIGHT...MODEL
SOUNDINGS SUGGEST THAT SUB-FREEZING AIR WILL EVENTUALLY WORK ITS
WAY CLOSE ENOUGH TO THE SURFACE TO ALLOW FOR SNOW TO MIX WITH
RAIN. HOWEVER...THIS CURRENTLY SEEMS MOST LIKELY TO OCCUR OVER THE
WESTERN HALF OF THE CWA...WHERE DRYING CONDITIONS AND A LOSS OF
ASCENT WILL BE LIMITING PRECIPITATION POTENTIAL AS TEMPERATURES
COOL. IN THE EASTERN CWA (ESPECIALLY CENTRAL OHIO)...WRAP-AROUND
WARM ADVECTION ON THE NORTH SIDE OF THE LOW CENTER IS NOW EXPECTED
TO KEEP TEMPERATURES TOO WARM FOR SNOW. THIS CHANGE HAS BEEN
REFLECTED IN THE GRIDS...WITH ALL RAIN EXPECTED THROUGH THE
COLUMBUS METRO AND EASTWARD. EVEN WHERE TEMPERATURES BECOME COLD
ENOUGH FOR SNOW (WHILE PRECIPITATION CONTINUES TO OCCUR)...THE WET
NATURE OF THE SETUP WILL KEEP THE CHANCE OF ACCUMULATION VERY LOW.
THIS ADJUSTMENT TO TEMPERATURES SATURDAY MORNING ALSO MEANS THAT
SUB-FREEZING CONDITIONS WILL ONLY BE LIKELY TO OCCUR WEST OF
US-68.

THE NORTHERLY FLOW BEHIND THE COLD FRONT ON FRIDAY NIGHT AND EARLY
SATURDAY WILL INCREASE SIGNIFICANTLY...BECOMING QUITE GUSTY. WIND
GUSTS OF 25 KNOTS (SOUTHERN CWA) TO 30 KNOTS (NORTHERN CWA) WILL
REMAIN IN THE FORECAST.

MODELS HAVE CONTINUED TO SUGGEST THAT LOW-LEVEL RH WILL BE
EXTREMELY SLOW TO SCOUR OUT ON SATURDAY AND INTO SATURDAY
NIGHT...AND SKY GRIDS HAVE BEEN INCREASED THROUGH THIS PERIOD OF
THE FORECAST. CONDITIONS ON SATURDAY ARE NOW EXPECTED TO REMAIN
RATHER CLOUDY...DOING NO FAVORS TO A MAX TEMPERATURE FORECAST IN
THE LOWER TO MID 40S...ABOUT 15 DEGREES BELOW NORMAL.

THE CHANGE TO THE CLOUD FORECAST IS ALSO RESULTING IN A SLIGHT
CHANGE IN THINKING FOR SATURDAY NIGHT / SUNDAY MORNING. WHAT ONCE
LOOKED LIKE AN EASY HARD FREEZE FOR THE ENTIRE CWA IS NOW SLIGHTLY
IN DOUBT FOR NORTHEAST KENTUCKY AND THE SCIOTO VALLEY. THE NEW
HAZARDOUS WEATHER OUTLOOK WILL REFLECT THIS THINKING (AND THE
LEVEL OF CONFIDENCE) IN MULTIPLE SEGMENTS.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
SKIES SHOULD CLEAR AND AS THE HIGH SHIFTS EAST RETURN FLOW WILL
SET UP STARTING TUESDAY WITH A WARMING TREND THAT WILL PUT
READINGS MORE TOWARDS NORMAL VALUES...SLIGHTLY WARMER ON OVERNIGHT
LOWS.

ANOTHER COLD FRONT WILL CROSS THE OHIO VALLEY ON TUESDAY. MODELS 
DIVERGE IN THE EVOLUTION OF THE SYSTEM. INITIAL FORECAST HAD THE 
FRONT CROSS EARLY TUESDAY AND HAVE DRY WEATHER OVER THE NORTHERN 
OHIO VALLEY. LATEST EUROPEAN MODEL COMES THROUGH WITH AN ELONGATED 
NE-SW TROUGH WITH A MID LEVEL STRONG SHORTWAVE RIDING NORTHEAST 
ALONG IT ON WEDNESDAY. THE FORECAST BLENDED THE TWO WITH AN INITIAL 
NOD TO THE GFS. FEEL THAT THIS MAY NEED TO LEAN TOWARDS THE WETTER 
AND MORE DYNAMIC EURO MODEL SOLUTION IN FUTURE FORECASTS.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
STRATOCUMULUS WILL DISSIPATE EARLY IN THE TAF PERIOD EXCEPT FOR
THE COLUMBUS AREA WHERE IT APPEARS THAT VFR CEILINGS MAY PERSIST
WELL INTO THE NIGHT. AN AREA OF MID CLOUDS WILL OVERSPREAD THE
AREA AFTER 00Z WITH CLOUDS LOWERING CLOSER TO 12Z. A COLD FRONT
WILL PUSH ACROSS THE TERMINALS LATE IN THE TAF PERIOD BRINGING
SHOWERS AND LIKELY MVFR CONDITIONS. WINDS WILL STRENGTHEN AND
VEER AFTER FRONTAL PASSAGE.

OUTLOOK...MVFR/IFR CEILINGS LIKELY FRIDAY AFTERNOON INTO SATURDAY
MORNING...WITH MVFR/IFR VISIBILITIES POSSIBLE. MVFR CEILINGS
LIKELY SATURDAY AFTERNOON INTO SATURDAY EVENING. GUSTY NORTH WINDS
UP TO 30 KT EXPECTED FRIDAY AFTERNOON INTO SATURDAY

&&

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

&&

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






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