Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 240640 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 240 AM EDT Mon Apr 24 2017 .SYNOPSIS... An area of upper level low pressure will continue moving slowly east across the deep south today, as drier air remains in place over the Ohio Valley. A mid-level ridge will gradually build into the area by the middle of the week, allowing for increasing temperatures and generally dry conditions. As a cold front moves into the region on Thursday, chances for precipitation will increase. && .NEAR TERM /THROUGH TODAY/... The 00Z KILN sounding sampled an extremely dry air mass between 850mb and 500mb. IR/WV satellite imagery depicts an interesting flow pattern through the mid-levels, in between the upper low over the deep south and a ridge off the east coast. There is a significant feed of moisture running northward between these features from Florida into eastern Kentucky, abruptly ceasing northward progress and spreading WSW and ENE at the col in the mid-level flow. Thus, the dry air mass just north of the mid- level wind shift -- and over Wilmington -- remains steadily in place for now. Interestingly, in both the high and low levels, flow moving into the middle Ohio Valley is gradually becoming more cyclonic and advective. Some patchy cirrus has already begun to move into the area, and an area of more notable low-level moisture (characterized by dewpoints in the upper 40s to near 50) is just nudging up against the southeastern ILN CWA border. Surface winds are expected to veer from NE to E throughout the day today, with a shift in flow at 850mb-700mb also allowing for an increase in moisture just off the surface today as well. The story has changed very little with regards to precipitation chances today, as the dry air will keep most of the CWA firmly dry all day -- and mostly clear in the low and mid levels at least to start the day. However, a 20-PoP has been maintained through the afternoon in the southeastern sections of the forecast area, closest to where the low level moisture is forecast to increase. By afternoon, there may be enough moisture spreading northwestward to allow for some scattered cumulus / stratocumulus development, necessitating an increase in sky cover during the second half of the day. This is unlikely to affect the far northwestern CWA, which (under generally clear skies) may again see the warmest temperatures of anywhere in the forecast area. && .SHORT TERM /TONIGHT THROUGH 6 PM TUESDAY/... By this evening, any chance for light rain will be coming to an end, setting up a dry forecast for the rest of the short term period. However, with wind flow aligning to southeasterly from 700mb to near the surface, an increase in mid and low level moisture will continue, prompting a continued increase in sky cover through the overnight and into Tuesday morning. Things change again on Tuesday morning, as an increased amount of warming at 5kft-10kft will likely lead to decreasing RH and a scattering of the cloud deck, eventually mixing into a cumulus field by afternoon. With ridging building in aloft and a switch to SSE flow at the surface, the pattern will set up for a more significant increase in temperatures -- reaching the middle to upper 70s across the ILN CWA. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Showers and thunderstorms will develop Wednesday night and Thursday when a cold front is forecast to swing through from the west. Western locations should see more a favorable environment for precip, with eastern sites having lower pops as the front moves into less conducive conditions aloft. The front may then stall south of the Ohio River Friday, before lifting back toward the Great Lakes on Saturday and Sunday. Shower and thunderstorm chances will persist in the moisture, instability, and convergence associated with the front. Warm temperatures will be the rule in a regime featuring above normal geopotential heights, though readings will vary somewhat with respect to frontal position. Highs in the mid 70s Tuesday will increase to the low 80s Wednesday under warm advection ahead of the cold front. A retreat back to the low 70s Thursday due to frontal passage will be followed by a rebound back to around 80 by next weekend. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... VFR conditions are expected through the TAF period. There will be a gradual increase in mid and high clouds through the period at all TAF sites, as well as a few low VFR clouds (generally above 4kft) making it into Cincinnati this morning and afternoon. If there is any potential for MVFR ceilings, it may occur briefly on Tuesday morning. Winds will remain out of the northeast today at around 10 knots, gradually shifting to the east by tonight into Tuesday. OUTLOOK...MVFR ceilings will be possible on Thursday along with a chance of thunderstorms. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hatzos NEAR TERM...Hatzos SHORT TERM...Hatzos LONG TERM...Coniglio AVIATION...Hatzos

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