Area Forecast Discussion
Issued by NWS Wilmington, OH

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136 FXUS61 KILN 300546 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 146 AM EDT Fri Sep 30 2016 .SYNOPSIS... A large area of low pressure will remain in place over the Ohio Valley through the rest of the week, providing cool and occasionally rainy conditions. Chances for rain will begin to diminish on Saturday, as the low gradually begins to move to the northeast. Drier and warmer conditions are expected for Sunday and Monday, with surface high pressure building in from the west. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Upper level low pressure system will continue to influence the weather pattern overnight. More widespread shower activity will work into the region during the overnight hours. This activity has already developed just southeast of the region and is beginning to move into the area. Due to this have increased precipitation chances for the overnight hours. There is some limited instability and therefore have isolated thunder in the forecast overnight as well. Temperatures will not drop much overnight with cloud cover therefore have low temperatures in the low to middle 50s. && .SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/... During the day Friday the upper level jet at 250 mb will strengthen over the eastern zones with the main low level convergence occurring over the northern part of the CWA. As the low rotates north Friday lower PWAT air that has wrapped around the low (0.75") will pull over the CWA with greater than 1.00" PWATs confined to the southwest and northern parts of the CWA. Have further refined PoPs to have the highest chances towards the north with slightly lower values across the central parts of the CWA. There also is instability present in both the GFS and NAM forecast soundings (between 500 and 1000 J/kg of ML CAPE) Friday afternoon which means thunder will be a possibility. Any slight wobble in the upper low can easily change the eventual location of higher precipitation totals. On Saturday the upper level low will head north towards the Indiana/ Michigan border with low level convergence and PVA increasing over the area. PWATs for Saturday aren`t impressive with values only around 1.00". Have gone ahead and increased PoPs for Saturday to account for the upper level lift mentioned above. && .LONG TERM /SUNDAY THROUGH THURSDAY/... The general consensus of the models is to start to lift the upper low off to the northeast through the day on Sunday. This should allow for a deceasing chance of pcpn by the start of the long term period and will just linger some slight chance pops across the area through Sunday afternoon. Highs on Sunday will generally be in the lower 70s. The 12Z ECMWF and the 12Z CMC are now maintaining a closed upper low through a good part of next week as it shifts off to the east, with the 12Z CMC slower pushing it east and even retrograding it some back across Pennsylvania through mid week. Meanwhile, the 12Z GFS continues it trend to weaken the upper low as it moves northeast while building some ridging across our area through the rest of the long term period. Likely as a result, there is also quite a bit of variability on the track of Matthew with it possibly riding up off the east coast through mid week. This all spells out some uncertainty in our sensible weather as we progress through the upcoming week. At this point will discount the CMC and lean toward more of a blend of the ECMWF and GFS, which would keep us mainly dry through mid week along with a gradual warming trend each day. The ECMWF is faster than the GFS with a possible front moving in through late week. Will again go with a blend and allow for some lower chance pops to work in from the west through the day on Thursday. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/...
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Slow moving low pressure in the upper atmosphere coupled with a surface trough and persistent moisture will continue to produce less than ideal flight conditions. Showers are generally moving north of TAF sites for now. However, IFR ceilings will likely form early in the forecast, probably increasing to MVFR and then VFR by the end of the forecast period. Shower activity will stay mainly around the periphery of the upper low as it travels toward CVG. This will allow the somewhat drier period with higher ceilings, though thunderstorms may develop this afternoon near northern sites DAY CMH and LCK, while showers linger in the vicinity of other sites. Winds will stay light in the weak surface pressure gradient, with direction shifting from northeast. OUTLOOK...MVFR ceilings and visibilities possible with showers through Saturday. IFR ceilings possible Sunday morning.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Haines NEAR TERM...Novak SHORT TERM...Haines LONG TERM...JGL AVIATION...Coniglio

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