Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 301327 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 927 AM EDT THU OCT 30 2014 .SYNOPSIS...
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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.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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SATELLITE IMAGERY SHOWS EXTENSIVE CLOUDS ACROSS PARTS OF THE NORTHWEST AND SOUTHEAST FORECAST AREA WITH LITTLE OR NO CLOUDS ELSEWHERE. THERE IS NOT A CLEAR CUT EVOLUTION...ALTHOUGH MODEL TRENDS SUGGESTS THAT THERE SHOULD BE A SLOW EROSION TO THESE LOWER CLOUDS. THERE WILL BE A BAND OF MID TO HIGH CLOUDS SPREADING IN DURING THE AFTERNOON ALTHOUGH IT DOES NOT APPEAR THAT THIS WILL BE A SOLID BAND. FORECAST HIGHS LOOK REASONABLE AT THIS POINT WITH LITTLE OR NO CHANGE.
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&& .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 /14Z THURSDAY THROUGH MONDAY/... SURFACE HIGH PRESSURE WILL SETTLE OVER THE OHIO VALLEY TODAY. SCT-BKN VFR STRATOCUMULUS WILL CONTINUE TO LINGER ACROSS THE REGION. MID AND HIGH LEVEL CLOUDS WILL SPREAD EAST INTO THE AREA BETWEEN 18Z AND 00Z. FOR TONIGHT...AN EMBEDDED DISTURBANCE ALOFT WILL INCREASE CLOUDS. THIS FEATURE IS FORECAST TO PASS JUST TO THE SOUTHWEST WITH PERHAPS A SMALL CHANCE OF A LIGHT SHOWER ENCROACHING NEAR THE KCVG/KLUK TERMINALS. ON FRIDAY...A POTENT UPPER LEVEL LOW WILL DIG SOUTHWARD INTO THE GREAT LAKES AND OHIO VALLEY. THIS SYSTEM WILL BRING AN INCREASE FOR SHOWERS ALONG AND BEHIND A STRENGTHENING COLD FRONT THAT WILL PUSH THROUGH DURING THE DAY. AVIATORS CAN EXPECT MVFR CONDITIONS WITH THE SHOWERS. GUSTY NORTHWEST WINDS TO 25 KNOTS WILL DEVELOP BEHIND THE FRONT. OUTLOOK...MVFR/IFR CEILINGS LIKELY FRIDAY NIGHT INTO SATURDAY MORNING...WITH MVFR/IFR VISIBILITIES POSSIBLE. MVFR CEILINGS LIKELY SATURDAY AFTERNOON INTO SATURDAY EVENING. GUSTY NORTH WINDS TO 30 KNOTS EXPECTED FRIDAY NIGHT INTO SATURDAY && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HATZOS NEAR TERM... SHORT TERM...HATZOS LONG TERM...FRANKS AVIATION...HICKMAN

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