Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 102050 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 350 PM EST Sun Dec 10 2017 .SYNOPSIS...
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A weak ridge of high pressure will build into the region late tonight. As this ridge moves east on Monday, a low pressure system will dive southeast to the Great Lakes and Ohio Valley. The low will strengthen as it pulls northeast Monday night, allowing a cold front to swing southeast through the region. Colder air will filter back into the area with the threat for snow showers Monday night into Tuesday.
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&& .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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A weak surface trough will move southeast through the region tonight. It will be followed by surface ridging which will linger into Monday morning. Moist ascent ahead of the trough and its associated disturbance aloft will result in lower level clouds to develop and move east/southeast across the region this evening and into early morning. Clouds may scatter some late. Lows will range from the lower to mid 20s.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
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The surface ridge will quickly move east Monday morning as a low pressure system (clipper) dives southeast into the Great Lakes. The majority of models now keep isentropically driven WAA precipitation north of the CWFA on Monday, so have a dry forecast. There will still be considerable mid/high level clouds. WAA will allow highs to range from the lower 30s north to the lower 40s south. For Monday night, the low pressure will deepen as it pivots northeast toward western New York. As this occurs, a cold front will move southeast through the region. Lift along the front, and moist CAA behind the front should result in a chance of snow showers. Precipitation may briefly mix with rain over the southeast. Lows will range from the mid 20s northwest to the lower 30s southeast. On Tuesday, a large scale deep mid level trough will reside over the eastern third of the U.S. and eastern Canada. Colder air (perhaps as cold as -18 C at 850 mb) on a northwest/north flow will move over the relatively warmer waters of the Great Lakes. This will keep the threat for some snow showers going, with perhaps a "streamer" developing off of Lake Michigan and extending southeast into our area. Highs will be early on with slowly falling temperatures through the day as CAA continues. By Tuesday night, the upper level trough will begin to move east, while a surface ridge builds toward the western Great Lakes and lower Ohio Valley. As the flow weakens and begins to back away from Lake Michigan, the threat for snow showers will taper off over the north through early morning. It will be cold with lows generally falling into the 10 to 15 degree range.
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&& .LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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Weak ridging will occur at the surface later on Wednesday. It will remain cold with highs ranging from the mid 20s north to the lower 30s south. Wednesday night has a chance for additional snowfall as models have a progressive cold front working in. European is an outlier at this point with a closed low tracking south of the region, but either solution puts a higher chance of snowfall in play. Cold air on the back side of this system will actually be relatively warmer than the arctic air in place at the surface when the system crosses. On Friday, the surface ridge axis crosses the region late in the day and a warm front sets up north of the area, permitting temperatures to return to near seasonal norms for the weekend due to a good warm push. GFS MOS has taken the highest temperatures that the ensembles have for the weekend, which may need to be adjusted upwards if enough warm air is being funnelled into the region as advertised. As the upper ridge breaks down later Saturday, models diverge in the surface features associated with the strong low that will cross the Great Lakes region early Sunday. GFS has a good cold front crossing the Ohio Valley while the European never turns the flow out of the southwest. Will opt for WPC guidance and just run with the model blend being this is day 7 of the forecast. After Wednesday night, the better chance for precipitation will occur on Saturday night in the form of rain. Given a wider variance in solutions this far out, timing and strength of these systems will keep a high amount of uncertainty in the forecast, for both temperatures and probability of precipitation.
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&& .AVIATION /21Z SUNDAY THROUGH FRIDAY/... Mid level clouds will move southeast away from the terminals by late this afternoon. Lower level clouds associated with a disturbance and surface trough will then move into the area from the northwest by this evening. There could be enough saturation to allow for some local MVFR ceilings near or north of KDAY and KCMH. For the overnight period, lower level clouds should become scattered. The surface trough will weaken as it moves. Winds will shift to the west/northwest, then they will become light and variable between 09Z and 12Z. On Monday, a clipper system will dive southeast to the Great Lakes region. The deepest and strongest Warm/moist ascent associated with this system is expected to remain well north of the terminals. Thus, precipitation should stay well north of the terminals with only mid clouds expected. Winds will be from the south between 5 and 10 knots. OUTLOOK...MVFR ceilings and visibilities possible Monday night into Tuesday and then again Wednesday night into Thursday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hickman NEAR TERM...Hickman SHORT TERM...Hickman LONG TERM...Franks AVIATION...Hickman

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