Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 300009 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 809 PM EDT Thu Sep 29 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 FRIDAY MORNING/... Upper level low was analyzed over southwest Ohio today via the 29.12z 250 mb map. Embedded in the upper low are pockets of PV that are rotating around. This afternoon coverage will continue to drift north and west around the low. The next wedge of PV is forecasted to rotate around the low and move overhead between 2 and 6z. At this time an inverted trough axis currently over West Virgina will also push west with a weak surface low pressure forming over the area. Omega values on the RAP, GFS, and NAM also all highlight lift during this time frame. PWATs at this time are forecasted to be around 1.1" with lower PWAT air being shunted west. High res models have come into pretty good agreement with timing so have increased PoPs during this time frame. Given the strong upper level lift moving overhead and a possibility for some higher rainfall totals will go ahead and highlight the chance for isolated heavy rain in the HWO. && .SHORT TERM /6 AM FRIDAY 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 /00Z FRIDAY THROUGH TUESDAY/...
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Showers and isolated thunderstorms will continue to move across the area overnight and into the day on Friday. Thunder will be pretty limited overnight and therefore kept thunder mention out of the TAFs at this time. Limited thunder mention to KDAY...KCMH...and KLCK for a few hours during the day on Friday. Stratus is expected to develop and be present for the overnight hours and into the daytime morning hours on Friday until slowly improving. IFR to LIFR conditions are once again expected overnight. VSBYs are also expected to be reduced with some of the shower activity and fog, however not expecting VSBYs to be as low overnight as they were last night. OUTLOOK...MVFR ceilings and visibilities possible with showers Friday afternoon through Saturday. IFR visibilities possible Friday night.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Haines NEAR TERM...Haines SHORT TERM...Haines LONG TERM...JGL AVIATION...Novak

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