119 FXUS61 KCLE 011742 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 142 PM EDT Tue Sep 1 2020 ...18z Aviation TAF Forecast Update... .SYNOPSIS... A warm front will lift north across the area today and stall the northwest over Michigan and Indiana. This front will push back south as a weak cold front on Wednesday. Low pressure will develop over the Lake Superior region on Thursday and extend a stronger cold front across the area on Thursday night. High pressure will enter the region for the weekend. && .NEAR TERM /THROUGH WEDNESDAY/... Some patchy dense fog has entered North Central and Central Ohio this morning with some visibilities near or below a quarter mile. Have a Special Weather Statement ongoing until 10 AM for these locations and will maintain patchy fog wording in the forecast. Previous Discussion... With high pressure well to the east of the area, southerly flow has ushered ample low-level moisture into the region this morning. Areas of low clouds and fog have crept in the southern and eastern portions of the forecast area, as the atmosphere quickly responds to this increased moisture. With sunrise, expect the fog and lower cumulus to mix out during the morning hours and more widespread and high cumulus to develop this afternoon. To the south, a weak warm front will move north today, bringing in an even more tropical air mass with dew points in the upper 60s to 70 degrees. The front itself is fairly weak and shouldn't force any convection as it stalls somewhere in the vicinity of Michigan and Indiana. A shortwave aloft will move east along this feature and be the forcing mechanism for shower and thunderstorm activity this evening and overnight. Precipitable water values approaching 2 inches in some areas depicts heavy rainfall as a concern, especially in NE OH, where recent rains has lowered flash flood guidance values to near 2 inches. There is also a non-zero severe thunderstorm threat as there will be convection in the region, but with modest instability in the later timing of the day and marginal shear, it appears difficult to get anything organized other than a couple of downbursts. This stalled front to the northwest will push southeast on Wednesday as a weak cold front. Moisture advection will be the main forcing for rain ahead of this front and with high moisture content, expect some efficient rainfall across the area. Coverage could be a bit of a concern, but expect all areas to get rain and have pushed for more likely/categorical PoPs. Temperatures through the period will remain near seasonal averages to perhaps a few degrees above. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... A shortwave trough works its way up from the southern Plains on Wednesday night while a deep, upper-level trough moves east across the Great Lakes region Thursday and Thursday night. At the surface, this will result in rather wet conditions ahead of an advancing cold front Wednesday night through Thursday evening. Greatest chance for rain will be Thursday afternoon/evening when an isolated thunderstorm may also be possible. The cold front is expected to make it's way across the region Thursday night. Strong cold air advection behind this cold front will result in a pattern change in the coming days. && .LONG TERM /SATURDAY THROUGH MONDAY/... Behind the aforementioned cold front comes an expansive high pressure, bringing quiet weather conditions and cool temperatures through the weekend. High temperatures on Friday and Saturday are expected to be in the 70s with near 80s returning on Sunday. Our next best chance for rain will come Monday once surface high pressure has exited the area to our east and the next low pressure system potentially approaches the area. && .AVIATION /18Z Tuesday THROUGH Sunday/... The main forecast concern for this TAF update will be the chance for scattered convection late this evening through the early morning hours of Wednesday. Also there is a good indication of lowering ceilings by early Wednesday morning down to at least low end MVFR and possibly IFR. Scattered to broken cumulus clouds around 5K feet will continue this afternoon becoming OVC by this evening. Scattered -SHRA will move in late this evening and overnight from the southwest. Have mentioned a TEMPO group for the best potential of timing with scattered -TSRA overnight into the early morning hours. Most of the guidance show good potential for lowering ceilings and visibility, IFR to lower end MVFR, through the morning hours on Wednesday after 10z. Winds will generally be southerly to southwesterly 5 to 12 knots. Some locally gusty winds up to 20 knots maybe possible for ERI late tonight and Wednesday morning. Outlook...Non-VFR possible with occasional showers and thunderstorms on Wednesday. Potential for non-VFR returns again with the passage of a stronger cold front Thursday night. && .MARINE... A cold front moving east across Michigan will stall out just northwest of Lake Erie today. Southerly winds ahead of this front of 5-15 knots will persist through at least early Wednesday morning before this front finally pushes east across Lake Erie. This will result in winds of 10-15 knots veering to out of the west during the day Wednesday. Another stronger cold front approaches the area from the west on Thursday with southwest winds of 15 knots developing during the day Thursday. This cold front moves east across Lake Erie Thursday night with cold air advection brining persistent northwest winds of at least 15 knots across Lake Erie late Thursday night through Saturday. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...Sefcovic NEAR TERM...Griffin/Sefcovic SHORT TERM...Saunders LONG TERM...Saunders AVIATION...Griffin MARINE...Saunders