Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 210606 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 206 AM EDT Mon Aug 21 2017 .SYNOPSIS... Above normal temperatures will persist across the Ohio Valley through Monday ahead of a cold front. The cold front will bring showers and thunderstorms on Tuesday, then drier and cooler air moves in for the rest of the week. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Just some mid and high clouds across the region this evening. But a disturbance in Illinois will track into the area overnight. This will bring some additional clouds and may result in a few showers primarily across northern counties. Temperatures will remain warm and have bumped up lows just a bit. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... Expectation is for any nocturnal upstream convection to have dissipated by the time it would make it into the CWA early Monday, although it`s not out of the question lingering showers make it into the far northwest CWA. Either way, some high clouds will be left behind for Monday morning. More cumulus are expected by afternoon as well, and therefore have started to trend the sky forecast upward a little for Monday, and it`s possible that much of the CWA could wind up more partly cloudy than mostly sunny for Monday. In addition, latest guidance suggests the potential for convective development in the afternoon/early evening mainly across the northwest portion of the CWA. Larger scale forcing is still best well northwest of the CWA, but moisture looks better and models suggest sufficient CAPE to generate a few cells as long as any capping erodes. Maxima will rise into the upper 80s, perhaps even hitting 90 in a few spots. Factoring in dewpoints in the mid 60s will yield heat index values into the mid 90s on Monday. Much of any convective activity on Monday would likely dissipate after the sun sets, but as a cold front approaches will continue with very low pops across the northwest corner of the CWA late at night. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... The main focus for the long term period will be the potential for severe weather and flash flooding on Tuesday. Thunderstorms will begin to move into northwestern portions of the forecast area Tuesday morning. In addition cannot rule out some isolated convection along and just southeast of Interstate 71 during the late morning and into the afternoon hours. These storms will have a damaging wind and hail potential. As the line of storms across northwestern portions of the forecast area move towards the southeast it will encounter a better environment with higher, although not substantial, cape values. Expect the main threat with the line to be damaging winds with locations northwest of Dayton having the lowest threat and a higher threat along and just southeast of Interstate 71. With the flow orientation believe that the wind threat south of the Ohio River will be a little less, however isolated damaging winds will still be possible. With the orientation of flow and the potential for the multiple rounds of thunderstorms, flash flooding will also be a concern generally southeast of Interstate 71. The cold front will move through Tuesday night. This will be followed by cooler and drier conditions for several days. With good CAA Wednesday and Thursday increased cloud cover substantially with cu expected to develop during the day on both of these days. Expect less cloud cover on Friday and Saturday as we lose the CAA. Temperatures Wednesday through Saturday will generally be in the 70s across most locations. Another system begins to approach for Sunday so there will be an increase in cloud cover and precipitation chances will begin to move back into the region. Temperatures will also be slightly warmer on Sunday with WAA. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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Surface high pressure was centered off to our southeast this morning with convection ongoing in Indiana. This convection is in response to a shortwave that is pushing east across northern Illinois. More stable air exists over Ohio though so am thinking convection will weaken before making it to the TAF sites. This afternoon high res models then indicate showers and thunderstorms possibly forming across our northwestern zones along the nose of a weak LLJ. The RAP, HRRR, WRF DART, and NMM show convection in some form or fashion while the NSSL WRF and NAM 3 km are dry. For now have just added a VCSH for KDAY due to uncertainty in formation. OUTLOOK...Thunderstorms are likely Tuesday into Tuesday evening.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...BPP NEAR TERM... SHORT TERM...BPP LONG TERM...Novak AVIATION...Haines

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