Area Forecast Discussion
Issued by NWS Wilmington, OH

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140 FXUS61 KILN 231448 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 1048 AM EDT Mon Apr 23 2018 .SYNOPSIS... An upper level low pressure system will push slowly east across the Tennessee and Ohio Valleys today through Tuesday, bringing rain showers to the region. High pressure and drier conditions will return for mid week. Cooler than normal high temperatures will persist through the end of the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Easterly flow at the surface is evaporating the northern edge of the precipitation shield. Mesoscale models are still indicating that the rain band will gradually overcome the drier air at low levels and will reach central Ohio by the end of the afternoon. Upped PoPs in the sw to 100, and increased Pops across all the southern half to categorical. Left northern areas as likely. Coolest highs are still expected in Cinci Tri-State where they will be around 60. Highs will increase as you head northeast towards Central Ohio where the highs will be in the mid to upper 60s.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... The upper level low will drift slowly eastward across the Tennessee Valley tonight through Tuesday and weaken somewhat as it does. This will keep the chance of showers going into Tuesday with the highest pops slowly shifting east across our area tonight into Tuesday. Instability looks to be marginal at best across our area, generally remaining to our south, so think thunder chances will be rather low. Lows tonight will be in the upper 40s to lower 50s with highs on Tuesday only in the mid to upper 50s. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Tuesday night a vertically stacked upper level low will be located over the Kentucky/ Tennessee border with another potent upper level disturbance located over Wisconsin. This secondary wave will dive southeast helping to eject the upper level low off quickly to the northeast Wednesday. There are some slight differences in the upper level flow depicted Wednesday with the ECMWF keeping the upper level low slightly deeper than the GFS and CMC. This means that for Wednesday afternoon the GFS, NAM, and CMC all only show exiting precipitation across the area, while the ECMWF is slightly more bullish. For now have just trended the precipitation to a slightly quicker exit for Wednesday. Wednesday evening an upper level disturbance over Wisconsin will move east pushing a surface cold front through the area. By this time enough dry air has moved into the region which will keep the area dry. There remains a lot of slight model differences beyond this period that still have to be resolved, but the general idea is for another upper level disturbance to push through the area Friday afternoon into evening allowing another cold front to pass through. For the most part Saturday through Monday looks dry with temperatures moving closer to normal. Confidence with this remains low though as multiple model to model and run to run consistencies are lacking. The first discrepancy exists Thursday afternoon as the ECMWF deepens the upper level low over Pennsylvania, while the CMC and GFS are more progressive. Since the GFS and CMC are more progressive they actually are stronger with the southern stream of PV keeping precipitation to the south (ECMWF has precip Thursday across our northeast). For now the ECMWF appears to be the outlier here, so have kept the area dry for Friday. For Saturday into Sunday another upper level trough axis will move across the area with the ECMWF and GFS now being the progressive models and the CMC wrapping up an upper level disturbance across Tennessee (544 dam heights). Given all the above, have kept the forecast dry, but this could easily change given the complex flow. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... An upper level low will push slowly east across the Tennessee and Ohio Valleys today through Tuesday morning. Precipitation associated with this has been steadily but slowly spreading north through the morning hours and this trend should continue through the rest of the day. The precipitation is moving into a relatively dry airmass so it will likely take much of the day for the precipitation to reach all the way to the northern TAF sites. Cigs will slowly fall through VFR today and eventually into MVFR as the lower levels begin to saturate later today. The threat for showers along with some MVFR conditions will then prevail through the remainder of the TAF period. OUTLOOK...MVFR ceilings will be possible through Wednesday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...JGL/Sites NEAR TERM...Sites SHORT TERM...JGL LONG TERM...Haines AVIATION...JGL is the U.S. government's official web portal to all federal, state and local government web resources and services.