Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 252340 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 740 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 /00Z SUNDAY THROUGH THURSDAY/...
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The leading line of showers and embedded thunderstorms is currently stretching from central Indiana down into central Kentucky. This line has been making a very slow eastward push and as we start to lose some of the diurnal heating, expect to see some weakening as it finally pushes into our western areas later this evening. As a result, will just allow for a vcsh late this evening and into the early morning hours at the western taf sites. A stronger mid level vort axis will rotate up across the area from the southwest late tonight into Sunday morning, eventually allowing for more widespread showers to develop from southwest to northeast. This should also allow for cigs and possibly vsbys to trend down into MVFR as we progress through Sunday morning. Instability remains fairly limited through the morning hours so think thunder chances will remain low enough to leave mention of thunder out of the TAFS through the morning. As we better destabilize through the afternoon hours, will go ahead and include a vcts to cover the thunder threat. OUTLOOK...MVFR ceilings and visibilities will be possible late Monday into Tuesday morning.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Haines NEAR TERM...Haines SHORT TERM...Haines LONG TERM...Novak AVIATION...JGL

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