Area Forecast Discussion
Issued by NWS Wilmington, OH

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KILN 202036 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 336 PM EST Sat Jan 20 2018 .SYNOPSIS...
-- Changed Discussion --
Southerly flow will lead to a continued warming trend through the weekend, along with a chance of rain. A better chance of rain showers will overspread the region through the day on Monday as a cold front approaches from the west. Showers will change to snow prior to ending Tuesday. High pressure will then offer dry conditions and near normal temperatures for the middle of the week.
-- End Changed Discussion --
&& .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/.. Westerly mid level flow with surface ridge axis east of ILN/s FA. A southerly low level flow will continue to advect warmer air and low level moisture into the region tonight. Moisture is rather shallow and forcing is weak with only a few sprinkles possible early this evening. Isentropic lift becomes a little more favorable late especially into the west late tonight. Therefore, will start pops as slight chance and only increase pops into the chance category overnight. With warm temperatures snow pack will continue to melt which will lead to some fog development. With wind staying up only expect a vsby restriction of 4 to 5 miles. Clouds and WAA on southwest winds will keep temperatures milder tonight with lows from the mid 30s north to near 40 south. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
-- Changed Discussion --
Surface low pressure develops in the central Plains Sunday and begins to eject northeast into the upper MS VLY Sunday night. Isentropic lift becomes more favorable Sunday morning and then shifts north over the Great Lakes Sunday night. Will continue chance pops with the best chance shifting north during the day light hours. On the warm side of the system, temperatures will be 10 to 13 degrees above normal Sunday with highs from the mid 40s northwest to the lower 50s southeast. With best lift and pressure condensation deficits shifting north Sunday night will allow the southeast counties to dry out while keeping chance pops over the northwest. Do not expect too much of a drop Sunday night with mild lows from near 40 northeast to the mid 40s southeast.
-- End Changed Discussion --
&& .LONG TERM /MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
On Monday morning, stacked low pressure is expected to be centered somewhere in the vicinity of St Joseph MO, moving on an ENE track from there into the southern Great Lakes. In an amplified pattern, deep-layer meridional flow will extend from the Gulf of Mexico into the Ohio Valley, providing continued warm advection through the day. Precipitation is expected to spread into the CWA from west to east during the day, starting as early as the morning hours. This appears tied to a pre-frontal trough rather than the actual cold front, which seems to not reach the area until later in the evening or overnight. Model soundings do not indicate that the boundary layer ever becomes truly mixed, which will limit wind gust potential to the 20-25 knot range, despite the stronger 850mb SSW winds (at least 50 knots). PoPs have been held at about 80 percent for this forecast update owing to some slight timing differences in the models, but this should eventually be bumped up to 100 percent as soon as this is pinned down. With temperatures running non-diurnally coming out of Sunday night, continued warming on Monday will bring max temps into the 50s (possibly lower 60s in the southeastern ILN CWA). With the low center lagging westerly compared to the position of the Monday night cold front, flow behind the front will exhibit a wind shift, but only veering to the WSW. The cold advection will lead to temperatures struggling to warm on Tuesday, but still a far cry from the cold fronts that have passed through in previous weeks. Max temps will actually be very close to normal (middle 30s to around 40) for both Tuesday and Wednesday. In terms of precipitation, after a break behind the cold front, some forcing and enhanced low-level RH will combine with some deeper mixing to allow for showers to develop across the southern Great Lakes and northern Ohio Valley. Have made some increases to PoPs on Tuesday for this, with an expectation that there will eventually be some snow mixing in as temperatures cool. Finally, but far from least important, is the issue of wind on Tuesday. The pressure gradient associated with the low will be relatively strong, and mixing will allow some higher winds to be tapped -- as opposed to the more isothermal sounding profiles expected for Monday. Gusts have been increased into the 25- 30 knot range and there is some room that this could increase, particularly in the northern ILN CWA. Broad surface high pressure will move east into the area during the second half of the week, as the upper pattern gradually switches from troughing to ridging over the eastern half of the CONUS. This will bring dry conditions and gradually warming temperatures through Friday. Behind the departing surface high, and with troughing developing over the plains, moist flow from the Gulf is expected to move into the Ohio Valley again over the weekend -- especially later Saturday into Sunday. Overall model agreement in this pattern remains strong across several GFS/ECMWF runs -- and without getting into specifics that far out, conditions appear warmer than normal with rain expected.
-- End Changed Discussion --
&& .AVIATION /20Z SATURDAY THROUGH THURSDAY/... Moist southwesterly flow on the backside of surface high pressure will result in the development of MVFR CIGS this afternoon. A few sprinkles or light rain will be possible late in the day into the overnight hours but have limited mention to VCSH due to limited impact and coverage. CIGS to lower to IFR category this evening with MVFR vsbys due to fog. These IFR conditions to continue into Sunday morning with a slow improvement to MVFR expected. OUTLOOK...MVFR cigs expected through Sunday night. MVFR cigs and vsbys in rain possible Monday, along with 25kt gusts. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...AR NEAR TERM...AR SHORT TERM...AR LONG TERM...Hatzos AVIATION...AR

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.