Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 231429 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 1029 AM EDT Mon Oct 23 2017 .SYNOPSIS... Copious moisture associated with a cold front and wave of low pressure will bring showers today and tonight. Showers will linger Tuesday into Wednesday when the low is forecast to meander across the Great Lakes. High pressure and dry weather will return on Thursday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Surface low pressure is currently located near Crawfordsville, Indiana. Though the overall surface pressure pattern is somewhat convoluted, an initial boundary is currently moving through the southern sections of the ILN CWA, while a more well-defined cold front will lag behind by several hours -- though it will travel largely along the same trajectory. The initial boundary has a thin line of enhanced showers along it, and it has been leading to some temporary SSW wind shifts, along with a drop in temperatures. Temperatures will drop more sharply behind the actual cold front in a few hours. Based on current precipitation patterns and HRRR/RAP temperature projections, some adjustments were necessary to temperatures, allowing for much more of a non-diurnal pattern through the day today than had been previously indicated. Still not seeing enough instability in model soundings to include thunder in the forecast, which will keep hazard potential to close to zero. This is good, since there is relatively strong southerly flow ahead of the low. Previous discussion > Surface map shows a cold front draped across Western Indiana. A strong wave of low pressure triggered by a closed upper low is centered over Southwest Indiana, with dew points in the mid 60s advecting northward on the east side of the low. Showers have developed along the front as expected, with rainfall rates enhanced near the wave of low pressure. As depicted by latest models and supported by radar, the wave of low pressure is lifting north through Indiana, while the cold front pivots into Ohio, bringing showers into the ILN area by mid morning, requiring categorical pops. The showers will then spread eastward and last through today, with intense rainfall rates at times in concentrated lift and moisture convergence under a 70 knot 500 mb flow ahead of the wave of low pressure. Flooding chances should be limited by lack of rain over the last 10 days leading to rather dry soils. Temperatures will still be above normal in the breezy southerly flow ahead of the front, with highs reaching the upper 60s.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... The cold front will move east this evening, while the wave of low pressure lifts to Michigan and then meanders over the Central Great Lakes through Tuesday. Showers will remain likely in the cool and moist cyclonic circulation behind the front, particularly in northern locations closer to the low. A slow diminishing trend in shower coverage and intensity should be evident as the low departs and weakens by Tuesday evening. Still expect one to two inches of rainfall for this event. Temperatures will be much cooler in the northwest flow behind the system. Highs Tuesday in the 50s will be about about 7 degrees below normal. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Highly amplified mid/upr level flow pattern characterized by deep trof over the Great Lakes and eastern U.S. and a mean ridge over the west to start the long term forecast period. This trof will keep a chance of a shower in the forecast until Wednesday afternoon. The best chance of a shower will occur across the northern counties. Wednesday will be the coldest day of the week, with highs ranging from the upper 40s northwest to the lower 50s southeast. These values will be close to 15 degrees below normal. Trof axis translates east with northwest flow developing and surface ridge building across the area Wednesday night. Frost will be possible, depending on cloud cover and how fast a southerly wind flow develops. Expect lows in the mid and upper 30s. Mid level ridging quickly builds across the region with a low level southerly flow increasing ahead of a front approaching from the west. Dry weather to continue Thursday with highs from the upper 50s northeast to the lower 60s southwest. Energy drops southeast carving out a mid level low over the upper MS Vly by the end of the week. Surface cold front pushes into the region but the airmass is initially dry. Will allow a chance of shower to develop in the post frontal environment over the west Friday afternoon. Expect a range of temperatures Friday with highs from the upper 50s northwest to the mid/upper 60s southeast. Mid level trof to settle into the Great Lakes next weekend. Model differences exist regarding how far south the closed low develops. Can not rule out a shower but with main moisture axis to our east and solution differences regarding location of the low, will limit pops to chance/slight chc category. Expect cool temperatures with highs Saturday in the lower/middle 50s and only in the upper 40s to lower 50s Sunday. && .AVIATION /14Z MONDAY THROUGH FRIDAY/... Aviation to be impacted by showers, low ceilings and wind shear ahead of a vigorous cold front. Conditions VFR to start will deteriorate by late morning as deep moisture streaming ahead of the cold front moves to TAF sites. Current radar indicates that CVG and LUK should see showers by 12z issuance or shortly thereafter. Other sites will have at least showers in the vicinity within a few hours. Prevailing showers will occur at all sites by 17z, accompanied by MVFR ceilings. CMH and LCK will experience a period of wind shear early this afternoon. After a brief return to VFR late in the afternoon, featuring VCSH and wind gusts to 20 knots, prevailing showers with MVFR are forecast to move back in for the evening into the overnight hours. OUTLOOK...MVFR ceilings and visibilities possible through Wednesday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Coniglio NEAR TERM...Coniglio/Hatzos SHORT TERM...Coniglio LONG TERM...AR AVIATION...Coniglio

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