Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 141040 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 640 AM EDT Sat Oct 14 2017 .SYNOPSIS... High pressure will remain centered southeast of the region today, providing dry conditions and increasing temperatures. A cold front will move through the region on Sunday, bringing showers and gusty winds. Dry weather and cooler air will settle in behind the front for the first half of the week, with warming temperatures expected heading into next weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Surface high pressure is expected to be centered southeast of the region today, shifting wind flow into a solid warm advection pattern through the boundary layer. A frontal zone is already setting up on the northern periphery of a mid-level ridge, which is centered over the southeastern CONUS. Ultimately, very little is expected to occur with regards to the weather over the ILN CWA today, outside of warming back into the 80s (again 10-15 degrees above normal) and some occasional mid-level clouds. Across the suite of models, the HRRR seems to be alone in projecting some light showers/sprinkles across the northwestern CWA this morning. Not an impossible scenario, with increasing clouds observed on satellite, but the probability of occurrence (and lack of any impact) will keep this out of the forecast at this issuance. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... Surface cyclogenesis will occur late Saturday in the plains, with low pressure deepening going into Saturday night and Sunday as it moves ENE into the Great Lakes. A cold front will extend SW from this surface cyclone, and this front is forecast to cross through the ILN CWA during the first half of the day on Sunday. For Saturday night, it still appears likely that precipitation will remain just outside the forecast area. Min temperatures may be reached early in the overnight period, as an increasing pressure gradient brings steady or rising temperatures by early morning. The biggest impact on Sunday will likely be from the overall synoptic wind fields, which are expected to increase in response to the deepening surface low. Even with that said, gusts are expected to remain below advisory criteria as of all current model projections, perhaps reaching as high as 30-35 knots in the northern CWA. The passage of the front will provide the greatest opportunity for gusts at this magnitude, but gusty winds may persist for a while behind it. Convective potential is very questionable, with model soundings indicating only some very shallow instability (under 200 J/kg in most cases) ahead of the front. What WRF-ARW/WRF-NMM models suggest may occur is that a line of convective showers (possibly with some thunder) right along the front should actually strengthen over the course of the morning and early afternoon, which would put the southeastern ILN CWA at the greatest risk of some convective enhancement to the winds. Nonetheless, with such meager instability, even the strong wind fields do not support much of a risk for anything beyond the magnitude of what has already been mentioned. Additional precipitation appears likely to occur behind the frontal passage. Non-diurnal temperatures were necessary on Sunday, as a very quick drop is expected once the front passes, even though -- for the northwestern ILN CWA -- that is expected to occur during what would otherwise be the upswing of the diurnal cycle. On the flip side, temperatures may briefly get quite warm in the Portsmouth area -- possibly pushing into the upper 70s before the front arrives. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Precipitation will come to an end across our east Sunday night as subsidence increases in the wake of the aforementioned frontal system. Skies will become partly cloudy as well. Temperatures will drop into the lower to mid 40s by Monday morning. Surface high pressure will build into our region on Monday, and then it will settle across the Ohio Valley by Tuesday morning. Mostly sunny skies on Monday will give way to clear conditions Monday night. Monday will be the coolest day of the week and will "feel" like fall given the warm temperatures experienced this month. With light to calm winds in our eastern zones, some patchy frost will be possible by Tuesday morning where temperatures will dip into the mid 30s. Upper 30s to lower 40s are forecast elsewhere. High pressure at the surface and eventually aloft will dominate the weather pattern for the remainder of the extended period. This will result in a warming trend along with continued dry weather. Highs will eventually warm into the lower to mid 70s which is above normal for the third week in October. Lows in the 30s and 40s will modify to all 40s by weeks end. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
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Early this morning, KLUK will experience LIFR fog, and some brief periods of MVFR fog are possible at the other TAF sites. VFR conditions will continue through the day today, with light southerly winds beginning to increase slightly. A more pronounced change is expected tonight, as clouds begin to increase (remaining VFR through the end of the TAF period) and winds become a little stronger out of the SSW. Some gusts are expected by early Sunday morning, though precipitation should hold off until after the TAF period ends. LLWS has also been introduced for most of the TAF sites, with strong 40-50 knot southwesterly flow at about 2kft off the surface. OUTLOOK...MVFR conditions and gusty winds are possible on Sunday, with showers and thunderstorms also possible.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hatzos NEAR TERM...Hatzos SHORT TERM...Hatzos LONG TERM...Hickman AVIATION...Hatzos

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