Area Forecast Discussion
Issued by NWS Wilmington, OH

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876 FXUS61 KILN 290235 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 1035 PM EDT Wed Sep 28 2016 .SYNOPSIS... A large low pressure system over northern Indiana will drift very slowly south into Kentucky...before reversing course and drifting back to the northwest toward Chicago...before very slowly weakening and losing grip over the Ohio Valley by the end of the weekend. Moist southerly to southeasterly flow around this low will keep rain and scattered thunderstorms in the picture all way into Sunday...with the better chances of rain focused on Thursday and Friday. Temperatures will remain below normal underneath frequent clouds and showers...before warmer and drier weather spreads through the Ohio Valley early next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... Upper level low will continue to meander near the area through the overnight hours and for the next several days. Precipitation has decreased in coverage and is primarily confined to extreme northern and eastern portions of the forecast area. There will continue to be a decrease in precipitation during the overnight hours, however some lingering shower activity will remain. There is a lot of low level moisture with many areas receiving widespread rainfall today and not breaking out of the clouds or not seeing breaks in the clouds until late. This combined with the nearby area of low pressure and light to calm winds, expect fog to develop overnight. Fog has already developed across some areas and expect additional fog and stratus development overnight. At this point have gone with areas of fog in the forecast. Some areas will likely see dense fog and conditions will continue to be monitored for the potential for a dense fog advisory across portions of the region. Temperatures are not expected to drop off much more overnight with the cloud cover therefore low temperatures in the upper 40s to low 50s are generally expected across the region. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/... Pesky closed low...with 500mb standardized anomalies to 2 or 2.5 sigma below climo...will drop south into southern KY by Thursday evening...before stalling. As it fills...this system will begin drifting aimlessly back into northern Indian by Saturday morning and there is strong agreement in the suite of NWP on this solution. This will guarantee a continued threat of episodic showers and storms Thursday...Friday...and Saturday...though with time the large scale forcing and cold-core of the system will weaken to the point that precipitation will become less organized and lighter...especially Saturday. Still-strong flow around this system will advect deep moisture off the Atlantic and into/across the Appalachian mountains and into the Ohio Valley through the end of the week. A particular area of enhanced rain threat will be across the northern/eastern CWA in closest proximity to deeper moisture and enhanced isentropic ascent. Given cold pool aloft...and slowly enhanced moisture in the boundary layer on both days...instability is sufficient enough that storms are possible...and will be drifting from SE to NW - a decidedly uncharacteristic storm motion. Both days will have a threat for an anchored or slowly moving arc of rain/ the heavy rain/minor flood threat is not completely out of the question. But as with all precipitation around closed upper lows...there is a wide disagreement in locations/timing of the individual vort lobes rotating around the central circulation...thus rain chances are not yet ramped up as high as they otherwise will likely be in coming forecasts. 60s by day and 50s by night in this reduced diurnal temperature range thanks to plenty of clouds. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... This period will be characterized by a much warmer drier/period vs the short term. On Sunday morning...the closed low will be drifting northeast...weakening...and opening up into a more progressive shortwave trough over New England by Monday. Thus...there is still a small threat of showers into Sunday but right now the timing/placement of this threat is very tough but seems focused north of I-70 closer to mid level cold pool. Large scale ridging ahead of the next longwave trough over the west will allow for dry weather Monday thru Wed as high pressure at the surface moves across the eastern U.S. Temperatures will be warming steadily and by the middle of next week should be well into 70s if not the lower 80s with dewpoints hanging tough in the 50s. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... Shower activity will decrease in coverage for the overnight hours and then pick up during the daytime hours on Thursday, especially during the afternoon to early evening hours. A few thunderstorms will also be possible around KCMH and KLCK later in the day on Thursday. Cigs and Vsbys will lower during the overnight hours and slowly improve during the day on Thursday. IFR to LIFR conditions will be possible at times overnight especially later in the overnight time frame Wednesday night into Thursday morning. OUTLOOK... MVFR ceilings and visibilities possible with showers Thursday night through Saturday. IFR/LIFR ceilings and visibilities possible Friday morning, with IFR ceilings and visibilities again possible on Saturday morning. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Binau NEAR TERM...Novak SHORT TERM...Binau LONG TERM...Binau AVIATION...Novak is the U.S. government's official web portal to all federal, state and local government web resources and services.