Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 191851 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 251 PM EDT Thu Apr 19 2018 .SYNOPSIS... A mid-level trough will move east of the region today, as surface high pressure envelopes the Great Lakes and Ohio Valley by tomorrow. Warming conditions are expected through the weekend, continuing into early next week. Low pressure moving south of the area will bring a chance of rain on Monday. && .NEAR TERM /THROUGH TONIGHT/... As a trough axis at 700mb is now well downstream of the ILN forecast area, a shift toward drier flow has occurred. There is already a warming of temperatures occurring through the boundary layer and even aloft, through the extent of a very dry inversion above 700mb. This is leading to a gradual erosion of the cloud deck, with skies ranging from essentially clear (NW Mercer County OH) to still quite cloudy (Lewis County KY). As skies continue to clear, and the air mass becomes drier, temperatures will cool relatively efficiently tonight. A freeze warning remains in effect for the area currently active in the program, with temperatures forecast in the lower 30s. It is possible the freeze may be marginal (around 32 degrees) in some of the southern ILN counties, especially as winds will not completely die off tonight, but per collaboration with surrounding offices there was no strong intention to remove the warning. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... An expansive area of surface high pressure will be moving into the region on Friday, with its center expected to be in southern Wisconsin by Friday afternoon. This air mass is expected to be very dry, with precipitable water values of around two tenths of an inch. Despite the cool northerly flow, the dry conditions and full sun should allow a decent warm-up from the freezing conditions of the early morning -- with max temps forecast to be in the middle to upper 50s. To note, this is still below normal, but it also represents the start of a more consistent warming trend. With as dry as things are through the atmosphere, the surface dewpoint forecasts could be too high, especially with decent mixing under full sun. Thus, Td values were adjusted downward slightly from the model blend during the afternoon. Temperatures were similarly adjusted upward by a degree or two. With a weak pressure gradient, however, winds should remain in the 5-15 MPH range. Winds will become even weaker heading into Friday night, where radiational cooling conditions should be fairly ideal. Another round of frost/freeze headlines could be necessary, but the warmer starting point (possibly negating a freeze) and dry conditions (possibly negating frost) make this a low confidence suggestion as of now. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... First half of the extended period will see benign weather has a large surface high pressure system settles over the midwest. Friday is looking mostly sunny with temperatures rising to the the lower to mid 50s. High clouds will begin to increase on Saturday as upper level moisture is forecast to still over the H5 ridge. Highs will push into the mid to upper 50s. Over the weekend, models push an upper level low out of the southern Rockies and into the southern Mississippi Valley. The upper low begins to fill as this occurs. Due to the southern track, the precipitation stays south of the region through the weekend. highs on Sunday will warm into the lower to mid 60s. As the models eject what is left of the low to the East Coast on Monday, some of the precipitation is pulled north into the region. Models are showing differences in how much and exactly where the pcpn will be, but there is enough certainty to put some low PoPs in the forecast for Monday into Tuesday. By Wednesday and H5 s/w drops down from the nrn Mississippi Valley. It merges with the initial upper low to bring additional chances of rain. Highs will generally be in the 60s for early next week. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... After a few remaining patchy MVFR ceilings lift over the next hour or two, VFR conditions are expected through the rest of the TAF period. The cumulus / stratocumulus clouds will continue to dissipate over the rest of the afternoon and evening, with clear skies expected overnight, and straight through the day tomorrow. Winds are slightly gusty out of the northwest at the moment, but will diminish in intensity later this afternoon. A switch to northerly or northeasterly winds is expected by tomorrow, but wind speeds should remain around 10 knots or less. OUTLOOK...No significant weather expected. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...Freeze Warning from 2 AM to 9 AM EDT Friday for OHZ060>065- 070>074-077>082-088. KY...Freeze Warning from 2 AM to 9 AM EDT Friday for KYZ089>100. IN...Freeze Warning from 2 AM to 9 AM EDT Friday for INZ050-058-059- 066-073>075-080. && $$ SYNOPSIS...Hatzos NEAR TERM...Hatzos SHORT TERM...Hatzos LONG TERM...Sites AVIATION...Hatzos

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