Area Forecast Discussion
Issued by NWS Wilmington, OH

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KILN 210559 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 1259 AM EST SUN DEC 21 2014 .SYNOPSIS... WEAK SURFACE HIGH PRESSURE WILL GRADUALLY MOVE EAST OF THE OHIO VALLEY BY SUNDAY. AS SOUTHERLY WIND FLOW INCREASES...TEMPERATURES WILL BEGIN TO WARM EARLY IN THE WEEK. CHANCES FOR RAIN WILL INCREASE BY TUESDAY...AS A STRONG LOW PRESSURE SYSTEM MOVES INTO THE GREAT LAKES. WINDY AND COOL CONDITIONS ARE EXPECTED AFTER THE LOW MOVES AWAY IN THE MIDDLE OF THE WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... FAST MOVG H5 S/W HAS KICKED OFF SOME FLURRIES IN CENTRAL OHIO LATE THIS AFTERNOON INTO THIS EVENING. LATEST RADAR LOOP IS SHOWING THAT THESE ARE SLOWLY EXITING THE REGION AND SHOULD BE GONE IN THE NEXT HOUR OR SO. THE PERSISTENT LOW LEVEL CLOUDS ARE FINALLY SHOWING SIGNS OF BREAKING UP...WITH CLEAR SKIES VISIBLE IN MUCH OF KENTUCKY. AS THE CENTER OF THE SFC HIGH DRIFTS EAST TONIGHT...EXPECT SOME OF THE CLEARING TO WORK INTO THE TRI-STATE. UPPED THE LOW TEMPS FRO TONIGHT A DEGREE OR TWO BASED ON THE AMOUNT OF CLOUD COVER EXPECTED TONIGHT. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/... A PATTERN CHANGE WILL BEGIN ON SUNDAY ACROSS THE OHIO VALLEY. SURFACE HIGH PRESSURE WILL BE CENTERED WELL EAST OF THE REGION...AND THE AXIS OF A LOW-AMPLITUDE MID-LEVEL RIDGE WILL BE SHIFTING GRADUALLY TO THE EAST AS WELL. THIS WILL SET UP A REGIME OF DEEP SOUTHERLY FLOW BY SUNDAY NIGHT...ESPECIALLY ONCE THE GRADIENTS BEGIN TO TIGHTEN IN ADVANCE OF THE TROUGHING MOVING THROUGH THE PLAINS STATES. DURING THE DAY ON SUNDAY...THE IMPACTS FROM THIS WILL BE RELATIVELY MINOR...WITH LITTLE TO NO CHANGE IN SURFACE FLOW. HOWEVER...WITH TEMPERATURES BEGINNING TO WARM ALOFT...SIGNIFICANT BREAKS IN THE CLOUDS ARE FINALLY EXPECTED TO DEVELOP. WITH SUN...TEMPERATURES WILL BE ABLE TO RISE 5-8 DEGREES FROM SATURDAY TO SUNDAY...ESPECIALLY IN THE SOUTHERN CWA (WHERE CLOUDS SHOULD ERODE MORE QUICKLY). AS MONDAY BEGINS...STRENGTHENING SSW 850MB WINDS WILL BEGIN TO FEED MOISTURE INTO THE MIDDLE OHIO VALLEY. ON THE NOSE OF THE MOISTURE PUSH...WEAK ISENTROPIC ASCENT WILL ALLOW FOR THE POSSIBILITY OF SOME LIGHT SHOWERS. FOLLOWING PROBABILITY PLOTS FROM THE 15Z SREF...IT APPEARS THAT ANYTHING THAT DEVELOPS WILL MOVE NORTHEAST THROUGH THE CWA BETWEEN 12Z AND 21Z...AND WILL NOT BE DIRECTLY ASSOCIATED WITH THE IMPENDING LARGE-SCALE ACTIVITY STILL FAR OFF TO THE WEST. COMING OUT OF ANOTHER COOL OVERNIGHT PERIOD...PRECIPITATION TYPE AT ONSET WOULD BE SOMEWHAT IN QUESTION...BUT ANY AMOUNTS ARE EXPECTED TO BE VERY LIGHT. ONLY A 20-PERCENT CHANCE WAS ADDED TO THE FORECAST. A SUBSTANTIAL WARMING IS EXPECTED ON MONDAY...AS LOW-LEVEL FLOW MAKES THE SWITCH TO THE SOUTH (SSW AT 850MB AND SSE AT THE SURFACE). A SLIGHT UPWARD ADJUSTMENT WAS MADE FROM THE PREVIOUS FORECAST...WITH LOWER 50S NOW EXPECTED IN THE FAR SOUTHERN CWA. STRENGTHENING FLOW WILL KEEP TEMPERATURES FROM FALLING MUCH ON MONDAY NIGHT...AND NON-DIURNAL TEMPERATURES WERE REQUIRED FOR THE FORECAST GRIDS. WITH A SLOWING IN THE MODEL TRENDS FOR THE PROGRESSION FOR THE NEXT SYSTEM...POPS WERE REDUCED FOR THE MONDAY NIGHT PERIOD...WITH THE ONSET OF WIDESPREAD PRECIPITATION APPEARING LIKELY TO HOLD OFF UNTIL TUESDAY. && .LONG TERM /TUESDAY THROUGH SATURDAY/... HAVE USED A BLEND OF THE 12Z ECMWF AND WPC GUIDANCE FOR THE LONG TERM FORECAST. THE ECMWF IS FASTER...DEEPER...BUT MORE QUICK TO TAKE STRONG LOW PRESSURE FROM THE OHIO VALLEY REGION TUESDAY NIGHT TO SOUTHERN ONTARIO BY THURSDAY MORNING. THE GFS IS SLOWER...NOT AS DEEP...AND ROTATES MORE OF A SFC TROUGH THROUGH THE REGION ON THURSDAY/CHRISTMAS. THE ECMWF/WPC BLEND IS PREFERRED AT THIS TIME. AN UPPER TROUGH IS FORECAST TO PIVOT AND BECOMES NEGATIVELY TILTED AS IT LIFTS THROUGH THE OHIO VALLEY TUESDAY NIGHT INTO WEDNESDAY. THIS SCENARIO WILL EVENTUALLY PUSH SURFACE LOW PRESSURE AND COLD FRONT ACROSS THE FORECAST AREA. ABOVE NORMAL TEMPERATURES ARE EXPECTED AHEAD OF THE SYSTEM WITH TEMPERATURES COOLING OFF TOWARD MORE SEASONAL NORMALS IN CAA BEHIND THE COLD FRONT. IN TERMS OF PCPN CHANCES...THEY ARE EXPECTED TO STEADILY INCREASE AS FORCING GETS CLOSER/STRONGER BY TUESDAY NIGHT INTO WEDNESDAY MORNING. AM EXPECTING RAIN SHOWERS ACROSS THE ENTIRE AREA TUESDAY INTO TUESDAY NIGHT. COVERAGE WILL DECREASE SOME ON WEDNESDAY AS THE STRONGEST LIFT MOVES NORTHEAST. THERE IS SOME EVIDENCE THAT SOME EMBEDDED THUNDER MAY OCCUR WITH THIS SYSTEM...BUT HAVE DECIDED TO HOLD OFF THE MENTION ATTM. COLDER AIR COMING IN ON THE BACK SIDE OF THE SYSTEM WILL CAUSE A CHANGE OVER TO SOME SNOW SHOWERS LATER WEDNESDAY INTO WEDNESDAY NIGHT. SNOW SHOWERS WILL TAPER OFF BY THURSDAY MORNING/CHRISTMAS. CONSIDERING THE WARMER AIR AHEAD OF THE SYSTEM AND TEMPERATURES BOTTOMING OUT MAINLY IN THE 30S BY THURSDAY MORNING...AM ONLY EXPECTING MINOR SNOW ACCUMULATIONS WITH THE SNOW SHOWER ACTIVITY. IT APPEARS THE BIGGEST IMPACT WITH THIS WEATHER SYSTEM WILL BE THE WIND. HOWEVER...WITH THE ECMWF SOLUTION...THE STRONGEST WINDS MAY REMAIN NORTH OF OUR AREA WEDNESDAY NIGHT. RIDGING DEVELOPS RATHER QUICKLY LATE THURSDAY AND MOVES EAST THURSDAY NIGHT. THIS WILL ALLOW FOR MODEST WARM AIR ADVECTION AHEAD OF THE NEXT LOW PRESSURE SYSTEM AND COLD FRONT THAT WILL APPROACH THE REGION ON FRIDAY. THE COLD FRONT WILL SLOWLY MOVE THROUGH THE AREA FRIDAY NIGHT AND SATURDAY. WILL CONTINUE WITH A CHANCE OF RAIN SHOWER AHEAD OF THE COLD FRONT WITH PERHAPS A BRIEF MIX WITH OR CHANGE OVER TO SOME SNOW SHOWERS BEFORE TAPERING OFF ON SATURDAY. TEMPERATURES WILL REBOUND AGAIN ON FRIDAY AND THEN COOL OFF TOWARD SEASONAL NORMALS BY SATURDAY. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
HIGH PRESSURE WILL ALLOW FOR DRY CONDITIONS ACROSS THE TAF SITES THROUGH THE TAF PERIOD. MVFR CLOUDS ARE BEGINNING TO ERODE AND WHERE THEY HAVE FOG HAS DEVELOPED. EXPECT MORE DISSIPATING OF THE CLOUDS OVERNIGHT EXCEPT AT KCMH AND KLCK. HAVE AT LEAST MVFR FOG DEVELOPING AT ALL THE TAF SITES OVERNIGHT AND IFR VSBYS AT KCVG...KLUK...KDAY...AND KILN. WITH KCMH AND KLCK EXPECTED TO HAVE MORE CLOUD COVER OVERNIGHT KEPT THEM IN THE MVFR CATEGORY. VSBYS WILL IMPROVE DURING THE DAY ON SUNDAY. THE DECREASE IN CLOUDS WILL GRADUALLY WORK INTO KCMH AND KLCK DURING THE DAY ON SUNDAY AND HAVE KCMH AND KLCK RETURNING TO VFR CONDITIONS SUNDAY AFTERNOON. OUTLOOK...MVFR/IFR CEILINGS AND VISIBILITIES ARE POSSIBLE TUESDAY INTO THURSDAY...ALONG WITH WINDY CONDITIONS.
-- End Changed Discussion --
&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HATZOS NEAR TERM...SITES SHORT TERM...HATZOS LONG TERM...HICKMAN AVIATION...NOVAK

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.