Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 252007 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 407 PM EDT Sat Mar 25 2017 .SYNOPSIS... Southerly flow ahead of low pressure will provide warm temperatures and mainly dry weather this afternoon. Showers and a few thunderstorms will develop tonight through Sunday as the area of low pressure approaches from the west. Another upper level disturbance will then move across the area Monday afternoon into Tuesday providing a continued chance of showers and thunderstorms for the area. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Temperatures have continued to rise this afternoon thanks to 850mb temperatures of 10 degrees C and 1000/ 850mb thicknesses of ~1380m. An upper level low over the central United States will slowly head northeast this afternoon with weak PVA and WAA moving overhead. Latest forecast soundings on the GFS and NAM show PWATs approaching 1.00" but a persistent CAP in place through the afternoon. Even with the elevated PWAT environment in place and weak lift, the lack of instability will keep the area dry this afternoon. This evening a weak band of showers and some embedded thunder will push into the western zones between 9pm and 12am. Lift for the precipitation will come from a band of weakening PV rotating around the upper level low. Omega values on the GFS would indicate the band breaking apart as it approaches the CWA with the NAM also hinting at this. Forecast soundings at this time show only very weak instability with even MUCAPE values of only 100 or 200 J/kg. Have kept thunder only slight chance for now Sunday morning given the weak instability. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... Later Sunday morning the upper level low will take on a negative tilt as it pulls northeast towards the Great Lakes. As this happens low level temperatures will fall and work together with daytime heating to steepen low level lapse rates. NAM forecast soundings are showing MUCAPE values around 1000 J/kg while the GFS is showing values slightly higher, around 1200 J/kg. At the same time areas of PV will be rotating around the upper level low providing a source of lift. In general, global and high res models are indicating the best lift across our eastern zones Sunday afternoon with a secondary source of PV in association with the low moving into the western zones. Forecast soundings on both the NAM and GFS have k index values in the low 30s Sunday afternoon with LI values briefly turning negative. PWATs at this time are also around 1.00". Due to the ample moisture, sufficient lift, and instability have kept likely PoPs or greater for Sunday afternoon. It should also be noted that at this time 0 - 3km bulk shear is around ~30kts. Thanks to the shear, instability, low level lapse rates SPC has the area in a marginal risk for isolated small hail and gusty winds. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... Showers and thunderstorms will taper off Sunday night as an upper level disturbance moves to the east. There will be a lull in the precipitation for much of the day on Monday before an upper level disturbance moves through Monday night into Tuesday. Precipitation will taper off Tuesday night. Moisture will be trapped across the area for Wednesday therefore increased sky cover and decreased temperatures some for Wednesday. The next system will begin to bring rain shower chances to the region on Thursday. Precipitation is expected to become more widespread Thursday night into Friday as a low pressure system nears the region. A cold front will move through Friday night. Precipitation chances will begin to decrease after the passage of this feature. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... All TAF sites currently VFR this afternoon as a surface low over the Midwest slowly pulls northeast. Latest runs of high res models continue to show precipitation moving in from the west around 6z Sunday morning. The showers and isolated thunder Sunday morning will move into the area in the form of a band and will likely loose cohesion as it progresses eastwards. Sunday afternoon forecast soundings begin to destabilize with ceilings lowering towards MVFR as the upper level low moves over central Indiana. As forecast soundings destabilize showers and thunderstorms will develop across the forecast area with higher coverage across our eastern TAF sites. Thunder will be likely in any storms that develop Sunday afternoon into evening. The chance of precipitation will continue into Sunday evening as the upper level low moves overhead. OUTLOOK...MVFR ceilings and visibilities will be possible late Monday into Tuesday morning. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Haines NEAR TERM...Haines SHORT TERM...Haines LONG TERM...Novak AVIATION...Haines

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