Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 160002 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 802 PM EDT Thu Mar 15 2018 .SYNOPSIS... A ridge of high pressure will move east through the Ohio Valley today, with dry weather expected to continue through Friday. On Friday night, an area of low pressure will begin to move east from Missouri through Kentucky. This will spread a mix of rain, freezing rain, and snow into the northern Ohio Valley. High pressure and dry conditions are forecast to return Sunday into Monday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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Back door cold front is through the CWA this evening and high pressure will strengthen as it builds in from the northwest. Generally clear skies will persist overnight and winds will turn from west-northwest to northerly. Continued clear skies overnight will allow for some decent drops in temperatures, also aided by the dry air mass, though the winds will not completely drop off. Min temps are expected to get well into the 20s through the entire CWA.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... With a surface front south of the area, the northern of the two areas of high pressure discussed above will drift southeast, centering itself over Lake Michigan by Friday afternoon. The air mass within this high will remain quite dry, and the low-levels will remain clear through the day. Winds will be much lighter, switching to the east as the day progresses. However, as a mid- level ridge axis passes through the area, an increase in high and mid clouds is expected by the end of the afternoon. Max temps will be a little more homogeneous than on Thursday,bet generally from around 40 to the middle 40s. More impactful weather is expected to move into the area on Friday night into Saturday morning. On Friday evening, a surface low is expected to be moving eastward into Missouri, with the earlier stalled frontal boundary stretching eastward from there and into the southern Ohio Valley. This front will begin to move to the north as it strengthens, with a tightening theta-e gradient developing between eastern Kentucky and northeastern Missouri. At and above 925mb, there will be a significant push of warm/moist air into the ILN CWA, especially between 00Z-12Z. As a result of increasing 850mb convergence, and ahead of a mid-level wave on the northeastern periphery of the surface low, precipitation will become widespread moving into the ILN CWA during this time frame. There will be quite a bit of warm air above sub-freezing surface temperatures, especially along and north of a line from about Ripley County IN to Lewis County KY. With greater confidence in the setup, freezing rain now looks likely to occur, especially along a swath through west central Ohio / Miami Valley area, and near / south of Columbus. Ice accumulations may be inhibited somewhat by ground conditions that will be warm to start with (with highs near 40 or so on Friday) but it does appear that up to a tenth of an inch will be possible. Will continue to mention this in the HWO, but an advisory decision was collaborated with neighboring WFOs to not be made this quite yet. Naturally, with a front in the area, non-diurnal temperatures were necessary -- with surface temperatures steadying out at around 06Z, then warming slightly through the rest of the early morning. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Period begins with the region under an area of wintry mix. Isentropic lift ahead of a surface low in srn Illinois will produce an area of mainly rain, with some snow or sleet on the extreme northern edge. Surface temperatures at the start of Saturday will be at or below freezing over the nrn half of the fa, so any rain there will fall as freezing rain. The surface low and upper support will shear se through KY during the day, bringing an end to the pcpn from north to south. Temperatures will rise above freezing Saturday morning bringing an end to the freezing rain threat. Highs on Saturday will range from the lower 40s in the north to the mid to upper 40s in the south. High pressure to build in for Saturday night into Sunday. Highs Sunday will range from the upper 40s to mid 50s. Next system will kick out of the west on Monday. Models are a little slower with the pcpn for Monday, leaving the majority of the region dry. A sheared H5 s/w will swing thru KY into srn OH by 12Z Tuesday. This will spread pcpn across the region Monday night. The majority of the region should see rain, but colder air might mix into the nw adding some wet snow. Models have trended towards a solution, which develops an upper trof in the east. This allows surface low pressure to linger in the upper Ohio Valley Wednesday. This keeps a chance of pcpn across the region during the middle of the weak. Critical thicknesses are low enough for snow Tuesday night, transitioning back to rain showers by Wednesday afternoon. As the system pulls out, Thursday, northerly flow will keep a chance of snow showers across the region. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/...
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VFR conditions will prevail as northwest winds turn northerly tonight. High pressure ridge in place will lift northeast during the day Friday, and east winds will set up ahead of the next system that will enter beyond the 24-30 hour time frame of the valid TAFs. High clouds will stream in from the west late in the forecast. OUTLOOK...MVFR ceilings and visibilities are possible on Saturday, along with a chance for some freezing rain.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hatzos NEAR TERM...Franks SHORT TERM...Hatzos LONG TERM...Sites AVIATION...Franks is the U.S. government's official web portal to all federal, state and local government web resources and services.