Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 221742 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 142 PM EDT Wed Mar 22 2017 .SYNOPSIS... High pressure will settle south into the Great Lakes and Ohio Valley today. The high will move east of the region tonight and Thursday. A warm front is expected to push northeast through the region Thursday night which may bring a few showers. After below normal temperatures today and tonight, a warming trend is expected into the upcoming weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Few to scattered stratocumulus in central Ohio will continue to diminish through the afternoon. Cool temperatures with northeast low level flow will persist.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... Models are in fairly decent agreement for the upcoming short term. For tonight, the center of the sprawling high will move to a position over the northern/central Appalachians by morning. Winds will veer east overnight as this occurs. Although some mid and high level clouds will begin spilling into the region from the west, it will still be a very cold night, especially over parts of central Ohio where clouds will be thin and winds the lightest. A new freeze warning for locations along and south of the Ohio River has been issued. There is some concern on the thickness of mid and high level clouds across western parts of this region. However, believe all locations even where cloud cover develops, will likely fall below freezing. Lows will range form the upper teens/lower 20s north to the mid and upper 20s south. On Thursday, low level southerly flow will increase on the back side of departing high. At the same time, a mid level ridge will begin to poke northward into the mid/upper Mississippi River Valley. WAA induced clouds will spread from west to east through the day. In fact, a warm front will be organizing to our west late in the day, which may bring a few showers to our western zones by evening. A modifying airmass will boost temperatures into the upper 40s far north to the mid/upper 50s along and south of the Ohio River. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... High pressure will be moving east of the ILN CWA on Thursday, stalling and weakening over coastal North Carolina on Thursday night. As this occurs, the 500mb pattern will be amplifying in the vicinity of the Ohio Valley, even as relatively tranquil conditions are expected at the start of the long term forecast period. Heights will be rising as ridging builds into the Mississippi Valley, as a complex low pressure system begins to take shape over the plains. This system will eventually lead to unsettled conditions through the weekend. To begin with on Friday morning, a north-to-south oriented warm front is expected to move NE through the ILN CWA. This front will be connected to the surface, allowing for an increase in southerly flow, and non-diurnal temperatures through the overnight and into Friday. However, the strongest push of theta-e advection will be at and above 850mb, leading to a strong inversion. The warmer and more moist conditions aloft will support elevated showers along the front, particularly across the northern sections of the ILN CWA, where forcing appears somewhat stronger. Both NAM and GFS solutions present some weak elevated instability based at around 800mb, so getting some convective showers or even thunderstorms may be possible. For now, the forecast will be kept sans thunder, but it might need to be added in later updates. Once this front has moved through by early Friday afternoon, dry conditions are expected, with the ILN CWA firmly in the warm sector. As a final note for Friday, the continued warming and a tightening pressure gradient will allow for somewhat of a mixed layer under the inversion -- along with gusts of 20-25 knots (maybe even a little higher in the NW CWA). After a dry period on Friday night and into early Saturday, attention on Saturday afternoon and evening will turn to a developing stacked low pressure center moving through Missouri. Confidence continues to increase in the overall timing and placement with this system, though recent model runs have allowed for a slightly slower overall progression, leading to drier expectations for much of Saturday. It is expected that there will be several rounds of showers (and potentially thunderstorms) along with this system, running primarily from Saturday evening through Sunday afternoon. Though the overall motion of the low will be slow, the juxtaposition of upper support, low level moisture transport, and 500mb vorticity advection will result in the possibility of multiple time periods in which showers and possibly thunderstorms will be able to develop. With 00Z GFS / 00Z ECMWF runs solidifying timing on the Saturday evening time period for one such wave of activity, PoPs have been increased to 70-80 percent, with generally 40-60 percent chances Saturday afternoon and then again through much of the rest of Sunday. Thunder has been included as a possibility on both days as well. This system will have a respectable feed of theta-e and a tight/compact 850mb-700mb low, so forcing and moisture should be sufficient for widespread precipitation. The possibility for heavier rainfall or strong storms is less certain, owing to differences in model specifics and a pattern that is not necessarily a classic setup for either threat. Nonetheless, there is at least a low-end potential to watch and refine the forecast for in the next few days. A narrow ridge behind the stacked low will provide a reasonable chance for dry conditions for Monday, but the short wavelengths in the busy 500mb pattern will mean that this dry period will not stick around for long. In fact, there is now increasing confidence that Monday night into Tuesday may time out for the next shortwave, and PoPs have been increased for this time frame. The warming trend on Friday is likely to bring temperatures into the 60s, and the slower progression of the incoming weather system will allow even further gains for Saturday, reaching the upper 60s to lower 70s. Near and behind the low on Sunday and Monday, temperatures will cool slightly, but should still remain above normal. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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VFR conditions will prevail. The few to scattered stratocumulus across the region will dissipate before 00Z. Otherwise will only see some cirrus spreading into the region during the latter part of the period. Northeast winds will diminish to less than 10 kt and then slowly veer tonight into Thursday. OUTLOOK...MVFR ceilings and visibilities likely Saturday night into Sunday along with a chance of thunderstorms.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...Freeze Warning from 11 PM this evening to 10 AM EDT Thursday for OHZ077>079-081-088. KY...Freeze Warning from 11 PM this evening to 10 AM EDT Thursday for KYZ089>100. IN...Freeze Warning from 11 PM this evening to 10 AM EDT Thursday for INZ073>075-080. && $$ SYNOPSIS...Hickman NEAR TERM... SHORT TERM...Hickman LONG TERM...Hatzos AVIATION... is the U.S. government's official web portal to all federal, state and local government web resources and services.