Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 181913 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 313 PM EDT Tue Apr 18 2017 .SYNOPSIS...
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High pressure centered over the interior Northeast will continue to move east today, allowing for return flow to become established in the Ohio Valley through tonight. A weak upper level disturbance to the north across the Great Lakes and to the south in the Tennessee Valley will push east tonight into early Wednesday morning, providing increased cloud cover in the area. A more potent system will move through the region Thursday afternoon into early Friday morning.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Surface high pressure centered over eastern Canada and the far interior Northeast continues to drift eastward, allowing for return flow to become established in the Ohio Valley. Although the area has seen plentiful sunshine thus far today, clouds will be on the increase from the south/southwest late this afternoon through the overnight hours. Convection-allowing models, particularly the HRRR, continue to suggest development of isolated to scattered shower activity late this afternoon for mainly southwestern parts of the FA. Although low level moisture is increasing, there continues to be quite a dewpoint depression in the FA, indicating a good deal of dry air in the lower levels. This being said, dewpoints are on the rise and expect that we may see a few returns on our radar by late this afternoon towards the Tri-State area, although precipitation may have a difficult time reaching the ground. Therefore, have maintained slight chance PoPs for parts of northern KY this afternoon into the evening. Whatever isolated activity develops late this afternoon into this evening will work its way east-northeast through the region tonight as cloud cover expands across the entire region. Isolated activity may focus across the far south/southeast late tonight, so have maintained chance and slight chance PoPs in these areas to account for this. With the anticipated development of thick cloud cover, and continued southerly flow, have bumped up lows for tonight by several degrees across the board. In fact, with dewpoints on the rise, temperatures may struggle to drop below 60 for many locations in the area. Have made very little adjustment to afternoon highs today as temp trends seem right on track.
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&& .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
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Wednesday morning will start off a bit overcast in the FA as the weak disturbance begins to move east of the region. Showers may linger longest across the southeast Wednesday morning before dissipating towards late morning and early afternoon. The focus will then shift to the potential for an area of showers and thunderstorms to develop along/on the southern fringe of a nearly-stationary boundary across northern IL/IN/OH during the late afternoon and early evening hours. Convection-allowing models continue to indicate the potential for this activity /if it develops at all/ to clip the far northern/northeastern FA late in the afternoon as it races southeast. Have added chance PoPs to account for this potential. Although cloud cover will be a bit more expansive during the day Wednesday, still think that highs may approach 80 degrees toward the Tri-State area during the afternoon. By Wednesday night, the aforementioned frontal boundary will begin to pivot back northward as a surface low pressure system organizes across the mid/northern Mississippi Valley. With the FA expected to be positioned squarely in the warm sector Wednesday night, an unseasonably warm night is expected, with lows dropping only into the low to mid 60s area-wide.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/...
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Southwesterly flow ahead of an approaching cold front will help push temperatures well into the 70s through the day on thursday with some lower 80s possible across our south. This will allow us to destabilize through the day on Thursday with an increasing chance of thunderstorms through the afternoon hours along a pre frontal boundary. The chance of showers and thunderstorms will then continue into the evening hours until the cold front moves through later Thursday night. Both deep and low level shear values will be on the increase as some upper level energy and the front approaches later thursday afternoon into Thursday evening. This will support at least a lower end severe threat, especially across our northwest fa where the better instability and shear values should reside. The front will push south of our area on Friday and then hang up across the Tennessee Valley through the weekend. There are some model differences as to just how far south of our area the front will make it and then how far north precipitation will spread back up into our area with various waves moving along the boundary Saturday into Sunday. Will generally keep pops in the chance category both days with the highest pops across our southern areas. Highs on Friday will be seasonable, ranging from the upper 50s in the north to the mid 60s in the south. Highs will then cool a bit for Saturday into the mid 50s to lower 60s, before returning to the low to mid 60s for Sunday. High pressure will build into the area for Monday before pushing off to the east through the day on Tuesday. This will lead to dry conditions and a bit of a warmup through the first part of the work week.
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&& .AVIATION /18Z TUESDAY THROUGH SUNDAY/... Very thin cirrus remain draped across parts of the region this afternoon. Midlevel clouds associated with a very weak mid- level disturbance over the Tennessee Valley region will gradually overspread the area from the south late this afternoon into this evening. Some of the hi-res suite of models continue to indicate isolated SHRA development this evening across southwestern parts of the area as a result of increased lift with the midlevel disturbance. As of right now, because of expected lack of coverage and ample dry air in the low levels, have withdrawn even a VCSH for all terminals for the period, even as isolated activity works ENE through the overnight period. As light sfc winds go more southerly this evening and eventually southwesterly tonight, low-level moisture will increase in the area. This will allow for MVFR, and potentially IFR, CIGs to develop and overspread the terminals after 06-09z. Do think that pockets of IFR CIGs will develop in the area, but do not yet have confidence on exact timing or location for inclusion as a prevailing condition at any of the terminals. CIGs may be slow to lift/scatter Wednesday, but do expect some clearing and lifting to VFR around/after 18z. OUTLOOK...MVFR ceilings possible Wednesday morning. Thunderstorms possible Thursday. MVFR ceilings and visibilities possible Saturday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...KC NEAR TERM...KC SHORT TERM...KC LONG TERM...JGL AVIATION...KC

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