Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 300623 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 123 AM EST Wed Nov 30 2016 .SYNOPSIS... Low pressure will approach the area from the south tonight allowing for showers to develop near central Tennessee and Kentucky. The showers and isolated thunder will then push northeast to the middle Ohio Valley late tonight into Wednesday morning. Most of the rain will fall southeast of the I-71 corridor and then colder air will enter in Wednesday evening behind a cold front. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Low pressure near south central Tennessee will ripple northeast to the middle Ohio Valley by Wednesday morning. This feature will be associated with moist ascent in the form of a LLJ. Highest chance for precipitation will be across south central Ohio and northeast Kentucky due to the low and its associated LLJ. The area between light precipitation and heavier precipitation will be near I-71 corridor. This is where a brief period of 850 mb to 700 mb frontogenesis develops. This region includes Cincinnati, Wilmington, and Columbus with the likely PoPs transitioning over to categorical as one heads east/southeast. Finally, west central Ohio, the Whitewater, and Miami Valleys will have the lowest chance with very light precipitation possible. Precipitation will be in form of showers. There may even be enough instability for a rumble of thunder, mainly over south central Ohio and northeast Kentucky. As for temperatures, they will fluctuate a little with some areas warming due to southerly flow and others cooling due to evaporative cooling. Overall, lower to mid 50s will be common by sunrise Wednesday. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY/... Wednesday after the sunrise the low will be exiting the area towards the northeast taking most of the rain with it. Wednesday afternoon there might be some brief breaks in the clouds before an upper level low in Minnesota begins to push east. As this happens a band of PVA will push through the area. A surface cold front will then push through with the PVA. The cold front will enter our western zones starting around 18z and then clear our eastern zones around 21z. Some high res models are hinting at some showers with isolated thunder possible with the front. Looking at forecast soundings there is some weak instability but confidence remains low on if there will be any instability at all. As the front pushes through the area Wednesday afternoon winds will begin to pick up and with gusts of 25 to 30 kts possible. Wednesday night into Thursday winds will stay gusty at times due to CAA and a tight pressure gradient. Forecast soundings for Thursday also keep 850mb saturated with clouds likely staying around all day Thursday and into Friday. The NAM has the low layer moisture staying around into Friday but has some partial clearing across our southwest. 850 mb temperatures fall to around six degrees below zero Thursday into Friday and with clouds around high temperatures will likely struggle to get out of the lower 40s. Have gone ahead and lowered high temperatures a bit Thursday into Friday. It also should be noted that Friday morning the GFS is saturating the low layers just enough to possibly have some flurries. For now have left the mention out as the GFS appears to be a bit to aggressive with the low layer moisture. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... A quasi-zonal flow pattern will be in place at the start of the weekend as our area will be in between a trough over eastern Canada and a developing upper level trough/low over the southwestern United States. Some weak pieces of energy will move quickly east across the southern Great Lakes Friday night through Saturday night. While it will be tough to rule out some spotty shower activity, the chance appears low enough at this point to go with a dry forecast through the first half of the weekend. Highs on Saturday will be at or a little below normal, ranging from the upper 30s in the northwest to the lower and mid 40s in the southeast. There is quite a bit of model uncertainty as we head into next week as both the 12Z GFS and the 12Z ECMWF have trended weaker and farther south with the initial energy ejecting out of the trough over the southwestern United States. The ECMWF is trying to phase some of this energy with a short wave pushing east across the Great Lakes Sunday into Sunday night while the GFS does not and keeps our area mainly dry. Will therefore go ahead and trim back pops a bit and just allow for some lower chances for primarily Sunday into Sunday evening. Depending on the exact timing, if any pcpn starts early enough on Sunday, it could be in the form of snow, before transitioning over to rain as we warm up in the afternoon. Expect highs on Sunday in the low to mid 40s. There is also some disagreement with how fast the main energy will eject northeast out of the western trough toward the end of the long term period. The GFS is weaker and somewhat faster with this compared to the ECMWF. Will go ahead and trend toward a blend and allow for chance pops to spread in from the southwest Monday night into Tuesday. Low level thermal fields are generally warm enough to support all rain with this event. Highs will trend a little above normal through the end of the period with highs by Tuesday ranging from the mid 40s north to the lower 50s south. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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First surge of pcpn is slipping south and east of the tafs. However as low pressure advances northeast up the edge of the Appalachians additional rain will develop along a deformation axis. Models swing this pcpn back across the wrn tafs between 08-12z. Tthe pcpn isn`t expected to be heavy and shouldn`t cause a deep reduction in visibilities. Ceilings are forecast to lower to MVFR this morning as low level moisture is pulled into the region ahead of the low. After 12Z, a cdfnt will move through the region. Models suggest a least a chance of showers with this frontal boundary. Winds will become a little gusty behind frontal passage. Conditions will also improve back to VFR behind the front. CAA tonight will bring increasing stratocumulus clouds. OUTLOOK...MVFR ceilings possible through Friday. MVFR ceilings and visibilities possible Sunday.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Haines/Hickman NEAR TERM...Haines/Hickman SHORT TERM...Haines LONG TERM...JGL AVIATION...Sites

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