Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 270556 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 1256 AM EST TUE JAN 27 2015 .SYNOPSIS... SURFACE HIGH PRESSURE WILL BUILD INTO THE OHIO VALLEY THROUGH THE MIDDLE OF THE WEEK. AN AREA OF LOW PRESSURE AND A COLD FRONT WILL MOVE ACROSS THE REGION ON THURSDAY...BRINGING A CHANCE OF MIXED PRECIPITATION. COLD HIGH PRESSURE WILL MOVE IN AGAIN ON FRIDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... MOSTLY CLEAR SKIES ACROSS MUCH OF THE REGION IN COMBINATION WITH LIGHT WINDS AND A FRESH SNOW PACK HAS ALLOWED TEMPERATURES TO FALL RAPIDLY. LOWERED TEMPERATURES FOR A VAST MAJORITY OF THE REGION...BUT MADE THE LOW TEMPERATURES A LITTLE AFTER MIDNIGHT...THEN WITH SLIGHTLY RISING TEMPERATURES AS CLOUDS TRY AND WORK BACK IN. WENT 0-5 ABOVE IN WEST CENTRAL OHIO AND SINGLE DIGITS FOR THE RURAL AREAS OF CENTRAL OHIO AND OVER TO THE MIAMI VALLEY. LOCATIONS FROM CINCINNATI SOUTHWESTWARD SHOULD STAY IN THE 20S. LOOKS LIKE THE CHANCE OF FLURRIES THAT IS ASSOCIATED WITH ENERGY DROPPING SE THROUGH INDIANA AND INTO KENTUCKY WILL STAY TO THE SW OF THE FA...SO DROPPED THE MENTION OF THEM IN THE TRI-STATE REGION. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/... THE SHORT TERM FORECAST PERIOD SHOULD BE FAIRLY QUIET...WITH NO CHANCES FOR PRECIPITATION. TEMPERATURES WILL BE THE BIGGEST CHALLENGE...WITH SURFACE HIGH PRESSURE SITTING OVER THE OHIO VALLEY...AND GENERALLY WEAK ADVECTION PATTERNS SETTING UP THROUGH WEDNESDAY. WITH GRADUALLY CLEARING SKIES...TUESDAY MAY END UP A DEGREE OR TWO WARMER THAN MONDAY...BUT THERE IS NO REASON TO FORECAST A BIG SWING IN TEMPERATURES. FOR TUESDAY NIGHT...CLEARING SKIES AND LIGHT WINDS WILL SET UP SOME VERY FAVORABLE RADIATIONAL COOLING CONDITIONS...AND THE ENTIRE MODEL SUITE HAS TAKEN A DOWNWARD TREND WITH TEMPERATURES. THIS FORECAST REPRESENTS A DROP OF SEVERAL DEGREES FROM THE PREVIOUS MIN TEMP GRID...BUT EVEN A SIMPLE GFS/NAM CONSENSUS BLEND WOULD RESULT IN COOLER CONDITIONS...SO THIS FORECAST STILL HAS ROOM FOR ADDITIONAL DOWNWARD ADJUSTMENT. ON WEDNESDAY...THERE ARE SIGNS THAT SOME WARM ADVECTION COULD BEGIN...THOUGH MAINLY JUST OFF THE SURFACE (AT LEAST THROUGH THE DAYTIME HOURS). AT 925MB...A RIDGE AXIS WILL HAVE TO CROSS EAST THROUGH THE REGION...BEFORE THE LOW-LEVEL FLOW TURNS FROM NNE TO SSW. THOUGH DIURNAL TEMPERATURES WERE USED IN THE FORECAST...IT IS POSSIBLE THAT MAX TEMPS COULD BE SLIGHTLY LATER THAN ON A TYPICAL DAY. WITH THE BOUNDARY BETWEEN SNOW PACK AND SNOW-LACK CUTTING ACROSS THE CWA...IF ANY WARM ADVECTION CAN COMBINE WITH THE PLENTIFUL INSOLATION ON WEDNESDAY...IT COULD HAVE A BIG IMPACT ON THE FINAL NUMBERS. THIS IS A LOW-CONFIDENCE TEMPERATURE FORECAST...ESPECIALLY WITH A FAIRLY TIGHT GRADIENT IN THE GRIDS...AND A MODEL BLEND WAS USED TO GET THE NUMBERS INTO REASONABLE POSITION. HOWEVER...THE EXTREMELY COLD VALUES IN THE CANADIAN MODEL WERE DISCARDED. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... FOR THE PERIOD WEDNESDAY NIGHT INTO THURSDAY NIGHT...THE ECMWF AND THE GFS STILL DIFFER A BIT ON THE TIMING OF A TANDEM OF S/WVS TO AFFECT THE REGION...ALONG WITH AN ASSOCIATED LOW PRESSURE/COLD FRONT. THE ECMWF IS SLIGHT SLOWER AND LITTLE MORE SHARPER WITH THE SECOND S/WV WHILE THE GFS IS FASTER. HAVE CONTINUED WITH THE GFS TIMING AT THIS TIME TO KEEP CONTINUITY FROM PREVIOUS FORECAST. WITH RETURN FLOW...TEMPERATURES WILL BEGIN TO WARM SOME LATE WEDNESDAY NIGHT INTO THURSDAY. THERE WILL BE A RACE BETWEEN HOW FAST IT WARMS COMPARED TO WHEN THE ONSET OF PCPN BEGINS. IT LOOKS LIKE THERE WILL BE A THREAT FOR A WINTRY MIX...SNOW...SLEET OR FREEZING RAIN FOR LOCATIONS ALONG AND NORTH OF THE OHIO RIVER LATE WEDNESDAY NIGHT INTO THURSDAY MORNING. BEST CHANCE WILL BE FROM EAST CENTRAL INDIANA INTO CENTRAL OHIO AND POINTS NORTH. MINOR SNOW...SLEET...OR ICE ACCUMULATIONS WILL BE POSSIBLE GIVEN A COLD START...ANY FREEZING RAIN WILL POSE A HAZARD TO TRAVEL SO WE WILL CONTINUE TO MONITOR THIS SYSTEM. HAVE MENTIONED THE THREAT IN THE HWO PRODUCT. PCPN IS EXPECTED TO CHANGE TO ALL RAIN BY THURSDAY AFTERNOON AS IT WARMS ABOVE FREEZING. PCPN SHOULD CHANGE BACK TO SNOW THURSDAY NIGHT IN THE WAKE OF THE COLD FRONT BEFORE ENDING BY FRIDAY MORNING. FOR FRIDAY INTO FRIDAY NIGHT...HIGH PRESSURE WILL ONCE AGAIN BUILD INTO THE REGION. TEMPERATURES WILL COOL BACK DOWN TO BELOW SEASONAL NORMALS. LONG RANGE MODELS DISAGREE ON HOW S/WV ENERGY FROM THE NRN BRANCH OF THE JET STREAM WILL EITHER PHASE OR NOT PHASE WITH SRN STREAM S/WV ENERGY. AS A RESULT...HAVE GONE WITH WPC FORECAST WHICH IS AN ENSEMBLE MEAN OF SOLUTIONS. THIS BRINGS A COLD FRONT THROUGH THE REGION SATURDAY NIGHT INTO SUNDAY WITH A CHANCE OF SNOW. COLDER AIR...OF THE ARCTIC VARIETY...SHOULD PUSH INTO THE REGION SUNDAY INTO MONDAY. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... CINCINNATI TERMINALS WILL BE ON THE EDGE OF LOW CLOUDS FROM THE WEST AND COLUMBUS TERMINALS ON THE EDGE OF LOW CLOUDS FROM THE EAST TO START THE TAF PERIOD. AFTER 12Z EXPECT LOW LEVEL MOISTURE TO SWING IN FROM THE NORTHEAST AND PERSIST THROUGH THE DAY. HOWEVER IT IS NOT CLEAR WHETHER THIS WILL MANIFEST ITSELF AS LOW CLOUDS. A BIT HIGHER CONFIDENCE OF MVFR CEILINGS DURING THE DAY IN COLUMBUS. LESS SO AT KDAY AND KILN. AT THIS POINT THINK CINCINNATI WILL BE VFR AFTER 12Z. LOW LEVEL MOISTURE WILL SLOWLY PULL OFF TO THE EAST LATE IN THE TAF PERIOD WHICH WOULD PUT AN END TO ANY MVFR CEILINGS. OUTLOOK...MVFR CEILINGS AND VISIBILITIES ALONG WITH A PERIOD OF FREEZING RAIN POSSIBLE THURSDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HATZOS/SITES NEAR TERM...SITES SHORT TERM...HATZOS LONG TERM...HICKMAN AVIATION...

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