Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 202346 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 746 PM EDT Sat May 20 2017 .SYNOPSIS... A warm front will progress northward through the area tonight allowing for scattered showers and thunderstorms. Some of the storms may contain heavy rain and gusty winds. Showers and thunderstorms will persist through Sunday afternoon when a cold front sweeps through the region. High pressure will build in for the beginning of the week offering drier and cooler conditions. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Mid/upper level low over the central plains to lift northeast into the western Great Lakes tonight. Upstream ridge axis to shift east with the flow backing in response to this system with an increase in moisture. Convective s/w aided the development of elevated convection in west central Ohio. This activity will continue pivoting northeast out of ILN/s FA early this evening. East-west oriented frontal boundary has stalled across northern KY. This front will begin to lift north this evening and push across ILN/s fa into southern Lower Mi overnight. Moderate instability has led to the develop of scattered storms over ILN/s southwest counties invof the warm front. 30-40 kt 0-6km bulk shear will support some organization to storms these storms. Downdraft cape 800-900 j/kg suggests the potential for a few of the stronger updrafts to produce strong to damaging wind gusts. As this activity moves north away from the genesis region of more favorable instability it is expected to weaken some. Model solns converging showing additional storms developing on pre-frontal sfc trof overnight. 925 mb favorable axis of convergence develops into eastern Indiana/western Ohio by 06Z. Moisture increases with an axis of pw/s values of 1.6 to 1.7 inches. These values are 175 percent of normal. Therefore potential for heavy rain and flooding will exist. Have categorical pops developing overnight with this feature. In warm sector and high moist environment have mild lows in the mid and upper 60s. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Expect ongoing convection associated with pre-frontal sfc trof Sunday morning. With pw/s of 1.6 to 1.7 inches, the potential for heavy rain and flooding will exist. The cold front will be slow to push through the region Sunday, which will provide a continued threat for storms. Instability is expected to be marginal. Highs on Sunday will be in the mid and upper 70s. A chance of pcpn will linger in the eastern counties Sunday evening before ending. Lows Sunday night will range from the lower 50s west to the mid/upper 50s east. && .LONG TERM /MONDAY THROUGH SATURDAY/... The ILN CWA will be in a dry period of cold advection starting on Monday morning, with a cold front moving east of the region, as a brief period of surface high pressure ensues. Though clearing skies are expected, the cooler air mass will result in a drop in max temps from Sunday to Monday, with highs in the upper 60s to around 70. With upper level low pressure north of the Great Lakes, the general flow pattern will gradually amplify, as the parent low spawns an another upper trough over the middle Mississippi Valley. Though there is decent agreement between models that most of the southern stream moisture will remain near and east of the Appalachian mountains, attention for the middle Ohio Valley will turn to the forcing just ahead of the low, which will result in gradually increasing precipitation chances from Tuesday afternoon through Wednesday morning. 00Z/06Z/12Z runs have forced a shift in the period of highest PoPs, now focused mainly on Wednesday. There has also been a general trend slower with the eastward progression of the upper low, which is unsurprising for closed upper systems in May. PoPs have been held back a little more significantly on Thursday, with slight chances introduced as well for Friday. This system will also result in a period of cooler temperatures for Wednesday and Thursday, possibly improving more significantly by Friday (unless the low continues to hang around through the end of the week). Behind the low, though timing confidence is marginal, there is high confidence that the overall pattern will switch to ridging over the southeastern states through the southern Great Lakes. This will allow for another round of increasing temperatures. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/...
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A warm front will lift north across the terminals this evening into early morning. There could be a chance of showers/storms with this boundary. Of concern in the next several hours is the convective line of showers/storms to the southwest of KCVG/KLUK. It looks like thunderstorms will affect this terminals between now and 04Z with MVFR ceilings and IFR visibilities. Models try to weaken this line as it heads east northeast. It may make it to KILN, but just come near or clip KDAY if it weakens. For late tonight into Sunday, we are still expecting widespread showers/storms ahead of a cold front as moisture plume interacts with low level convergence ahead of the cold front. Widespread rainfall will allow the predominate ceilings to drop below 2000 feet with MVFR visibilities for a period of time. After frontal passage, precipitation should end with ceilings and visibilities rebounding back to VFR by mid to late afternoon. For Sunday night, dry slot will move in behind the front. It is unclear if any wrap around stratocumulus clouds will filter into the region in the CAA. Will continue to monitor this potential with next TAF package. OUTLOOK...Thunderstorms possible Tuesday. MVFR ceilings possible Wednesday and Thursday.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...AR NEAR TERM...AR SHORT TERM...AR LONG TERM...Hatzos AVIATION...Hickman

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