Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 210609 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 209 AM EDT Fri Oct 21 2016 .SYNOPSIS... Occasional showers will continue into tonight before tapering off through the day on Friday as a cold front pushes slowly through the area. A much colder airmass will filter into the region behind the front with below normal readings expected for Friday and Saturday. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... The frontal boundary is now southeast of the area. Marginal severe weather threat has diminished with decreasing forcing and instability. Put slight chance of thunder back in after noticing a few lighting strikes. Meanwhile, the upper level trough will shift east across the area tonight with an associated 850-500 mb deformation axis pivoting slowly east into our area. Pcpn associated with this feature is lifting up across western Ohio and this should continue to very gradually work its way east across our area tonight. Breezy conditions will be evident tonight in the tight pressure gradient behind the front and gusts will reach close to 30 mph out of the north. Lows will be in the upper 40s to around 50. && .SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/... The upper level trough and the deformation axis will continue to shift off to the east through the day on Friday. This will allow for light showers to gradually taper off from west to east across the area through the day. In northerly low level flow on the back side of the trough, decent CAA will persist through the day with 850 mb temperatures dropping down below zero degrees celsius by late afternoon. The combination of this and some lingering clouds should help limit temperatures through the day with highs only in the low to mid 50s. Northwesterly low level flow will continue Friday night and this could allow for a few lingering clouds as we get a bit of a fetch off of Lake Michigan. Lows Friday night will be dependent on the amount of cloud cover and whether or not the winds stay up a little. For now will go with lows in the upper 30s to lower 40s but if we end up with more clearing and light winds, this may be too warm and frost would become a concern. Surface high pressure will begin to build up into the Tennessee Valley through the day on Saturday. This will lead to dry conditions heading into the weekend but with the cold air mass still in place, expect highs on Saturday only in the mid 50s. && .LONG TERM /SUNDAY THROUGH THURSDAY/... On Sunday the upper level low and trough axis will be over the Northeast United States with surface high pressure located over the Southeastern United States. 850 mb temperatures will slowly rise to just below 10 degrees C which will support high temperatures in the mid to upper 60s. Sunday night into Monday morning a shortwave will push southeast down mid-level ridging and around the upper level low. The GFS is slightly more progressive and weaker with the shortwave compared to the ECMWF. Both 20.12z model runs bring the shortwave slightly further west than yesterday and therefore try to bring the heart of the colder air slightly further west as well. The ECMWF and the GFS push the front through the area by Monday evening. The frontal passage also appears to be a dry frontal passage as PWATs remain around 0.60". Behind the front highs will cool down back to normal as the heart of the cold air still misses the area (850 mb temperatures around 4 degrees C). Tuesday the upper level trough will finally head east of the area taking the cooler air with it. Wednesday into Thursday a shortwave will eject out of the midwest and approach the area. This means clouds will begin to increase on Wednesday and into Thursday. Have also introduced a chance of rain into the forecast Thursday as the low approaches. PWATs on the GFS rise to above 1.00" with limited instability. Upper level forcing looks good though as the ILN forecast area is in the diffluent side of the trough axis and widespread PV moves over the area. For now have just edged the chance of precipitation up as model consistency remains low at this time. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/...
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A weak area of low pressure east of the terminals continues to lift northeast away from the area. Waves of -SHRA will continue to push northeast through the area during the overnight hours as the deformation axis slowly pivots eastward. Have seen some redevelopment of -SHRA west of main pcpn and hi-res models are picking up well on this additional development. As such, have added prevailing pcpn at all sites except KCVG and KLUK through the overnight. Latest model runs are suggesting that back edge of deformation axis pcpn will be a bit slower to swing east through the area during the morning and early afternoon. As such, expect pcpn to come to an end around 14z for western sites of KDAY, KCVG, and KLUK and around 18z for eastern sites of KCMH and KLCK. Heaviest pockets of pcpn may result in brief MVFR VSBYs. CIGs will hover around 1k ft across all terminals through 15z and will likely bounce periodically between IFR and low MVFR during that span. IFR CIGs will be more likely in pockets of higher pcpn. CIGs will gradually go MVFR and potentially even VFR for western sites during the afternoon. However, do think that CIGs will remain MVFR across the east through at least 00z Saturday. As the sfc low continues to pull away from the area, a tighter pressure gradient will move in, allowing for northerly/northwesterly winds of around 15 kts with gusts to 25 kts through the afternoon. Although the tight gradient will persist longer for eastern sites into the evening, do expect a gradual weakening trend past 00z Saturday. OUTLOOK...No significant weather expected.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...JGL NEAR TERM...Coniglio/JGL SHORT TERM...JGL LONG TERM...Haines AVIATION...KC is the U.S. government's official web portal to all federal, state and local government web resources and services.