Area Forecast Discussion
Issued by NWS Wilmington, OH

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978 FXUS61 KILN 270236 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 1036 PM EDT Mon Sep 26 2016 .SYNOPSIS... A cold front has pushed through the forecast area this afternoon with cooler and drier weather behind it. An upper level low pressure system is expected to move into the Great Lakes and Ohio Valley by mid week which will keep the weather cool due to clouds and the threat for showers. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... In the wake of surface cold front, skies have cleared from west to east this evening. A few clouds remain in the far southeast counties but this clearing trend will continue with clear skies persisting through the overnight hours. Much drier and cool airmass to advect in on west to southwest winds. Surface dewpoints which were in the lower/middle 60s this morning, will drop through the 40s overnight. Low temperatures are expected to be in the middle and upper 40s by sunrise. These readings will be around 5 degrees below normal. Previous Discussion... The surface cold front has cleared the CWA with only some light rain occurring across our eastern zones. Drier and cooler conditions will then move in behind the front. The clearing line should move through the forecast area this afternoon into evening. Tuesday morning behind the front much cooler air will work into the area with lows in the mid to upper 40s expected. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY NIGHT/... Tuesday a vertically stacked upper level low will start to drift south keeping the low level gradient tight. Clear skies will also promote deep mixing (~800 mb) which will allow winds to breezy at times. Both GFS and NAM forecast soundings are indicating wind gusts up to 30 mph possible at times (via momentum transfer) and sustained winds of 15 to 20 mph. Current wind and wind gust grids looked good so have made only minor changes here. Afternoon highs Tuesday will also reach in to the lower 70s as 850 mb temperatures hover just under 10 degrees C and 1000/850 mb thicknesses fall to 1375 m. Tuesday night into Wednesday morning the upper level low will continue to drift south allowing PWATs to rise from under 0.40" back up to just under 1.00" in places. By late Wednesday afternoon the upper level low will be just north of the forecast area bringing clouds and the chance of rain back to the area. Forecast soundings on both the GFS and NAM also show some weak instability Wednesday afternoon towards the south. Given the instability and upper level lift can`t rule out a couple of strikes of lightning. Wednesday night into Thursday the upper level low will pinch off from the main flow and remain quasi-stationary over the Ohio valley. The GFS, CMC, ECMWF, and UKMET have all come into pretty good agreement with this. In general, this would support chance showers and isolated thunderstorms with a smaller diurnal range every day. Have lowered max temps a bit to account for this. && .LONG TERM /FRIDAY THROUGH MONDAY/... The GFS has continued to trend more in line with the ECMWF, lingering the upper level low across the region through at least the end of the week. As a result, have continued to nudge up pops each day through Saturday and tweaked down temperatures a bit. Beyond that, both the GFS and ECMWF are trying to lift the low northeastward and out of the area, although the ECMWF is still slower in that process. At this point, will keep Sunday and Monday dry but again, if things continue to trend toward the slower ECMWF, we may need to introduce some low end pops into early next week and lower temperatures a bit more toward the end of the long term period. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Surface cold front has pushed east of the TAF sites into western Pa. Precipitation associated with the frontal system has pushed off to the east. Conditions have improved to VFR behind this front. Expect clear sky conditions through the overnight hours. Drier air advecting in on west winds around 5 kts will inhibit fog development tonight. VFR conditions to continue Tuesday with only few to scattered cumulus clouds expected. Winds from the west will subside to around 5 kts tonight. On Tuesday wind will back southwest and speeds will increase with gusts above 20 knots. OUTLOOK...Rain and MVFR ceilings are possible from Wednesday through Friday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Haines NEAR TERM...Haines/AR SHORT TERM...Haines LONG TERM...JGL AVIATION...AR is the U.S. government's official web portal to all federal, state and local government web resources and services.