Area Forecast Discussion
Issued by NWS Wilmington, OH

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785 FXUS61 KILN 180930 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 430 AM EST Wed Jan 18 2017 .SYNOPSIS...
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High pressure and drier air will move in from the southwest today. Low pressure traveling to the Great Lakes will bring showers back into the forecast late Thursday into Friday. Mild and mainly dry weather is expected Saturday in the southerly flow behind the low.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Cold front is to the east, pushed by a closed 5520 meter 500 mb low. Drizzle occurring in persistent low level moisture will diminish by mid morning as the upper low and associated forcing depart east. This will leave cloudy skies through early afternoon, with some breaks possibly showing up later as high pressure moves to near Evansville. Temperatures rising to the lower 40s will be limited by the weak insolation and cold advection on a west wind.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
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High pressure moving across Kentucky to West Virginia should keep dry weather over the ILN area tonight through early Thursday. Skies will probably remain partly to mostly cloudy with low level moisture persisting under an inversion around the periphery of the high. Low pressure developing to the west on Thursday will move up the flank of an upper ridge to the vicinity of Chicago by Friday morning. A stream of moisture carried by a 35 knot low level jet will be lifted on the warm conveyor belt ahead of the low, producing widespread rain. Models indicate around a half an inch of rainfall with this event. The rain will end Friday morning as the low weakens and redevelops over the northern plains. A relatively dry southerly flow in the wake of the low, coupled with above normal geopotential heights and weak forcing aloft, should result in dry weather conditions Friday afternoon. Temperatures will exhibit an upward trend in this warm advection regime, with highs mainly in the lower 50s Thursday, increasing to the mid and upper 50s Friday. These anomalously high temperatures will be occurring when normal highs are in the mid and upper 30s.
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&& .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
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In the wake of Fridays closed low there will be a brief period of subsidence on the backside of the PV, but the main question is how quickly will the precipitation return. Overall ridging begins to setup across eastern Canada and the northeastern United States with an upper level trough over the western United States. The pattern will be messy though as multiple waves of mid-level energy can be found in the flow. The GFS is slightly further east with an upper level low pushing north on the western side of the mid-level ridge. As this occurs the ridge will slowly start to move east. The GFS is slightly stronger with this low Saturday and tries to bring in precip to the area Saturday afternoon across the western zones. The CMC looks similar to the GFS while the ECMWF is slightly weaker with the energy Saturday. Looking at forecast soundings on the GFS for Saturday shows dry air between 850 and 700 mb which would favor a later onset of precipitation. Given the above have trended the forecast towards the ECMWF solution and kept Saturday drier. Sunday, another stronger piece of energy will push east across the southern United States and wrap up into an upper level low. As this happens a wedge of PV will push northeast ahead of the low and move across the ILN forecast area. PWATs at this time again rise to around 1.00". Forecast soundings on the GFS show some dry air trying to remain in various levels of the sounding at this time so have kept PoPs at chance. Seeing how strong the upper level lift currently looks on the ECMWF and GFS Sunday, PoPs will probably have to be raised. Sunday into Monday the upper level low will drift overhead keeping the clouds and a chance of rain in the forecast. It should be noted that the low looks to be vertically stacked with dry air entrained. This means that a break in the precip will probably occur sometime on Monday (possibly in the morning) but given this is day 7 have just broad brushed the PoPs at this time. On Tuesday the upper level low will slowly drift east taking the rain and precipitation with it.
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&& .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... Mid level shortwave evident on water vapor imagery, rotating through the Great Lakes. Shallow low level moisture leading to areas of drizzle along with some rain showers. Low level CAA will allow for MVFR to IFR stratocu with drizzle continuing through about 13z when the low level CAA transitions to WAA. MVFR cigs will persist through much of the day with some gradual improvement possible from the southwest this evening as the low level flow begins to back. West winds around 10 kts will persist through the day and then back southwest at less than 10 kts tonight. OUTLOOK...MVFR/IFR ceilings possible into Thursday. MVFR/ IFR ceilings are again possible Thursday night into Sunday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Coniglio NEAR TERM...Coniglio SHORT TERM...Coniglio LONG TERM...Haines AVIATION...AR

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