Area Forecast Discussion
Issued by NWS Cleveland, OH
Issued by NWS Cleveland, OH
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129 FXUS61 KCLE 300833 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 419 AM EDT Mon Sep 30 2024 .SYNOPSIS... A trough lingers across the area today before departing to the east. A cold front will swing east across the area on Tuesday and Tuesday night. High pressure builds in on Wednesday and Thursday with a weak cold front moving across the area on Friday. && .NEAR TERM /THROUGH TUESDAY/... An upper-level low that has been influencing our weekend weather still remains over the Ohio Valley, albeit in a significantly weaker state. Low-level moisture in the 850-925mb layer is quite expansive, extending across the entire forecast area, though deeper moisture to 700-500mb is primarily located east of the upper-level low trough axis into the far southeast part of our forecast area (i.e. approximately KGKJ to MNN). We start the day today with overcast skies areawide and isolated, light rain showers possible underneath the deeper moisture. Isolated showers remain possible in our southeast counties through today and tonight as the upper-level low is very slow to move east, though overcast conditions should give way to partly to mostly cloudy skies as some scattering out of the low-level clouds should occur with some mild daytime heating. Conditions become favorable for patchy to areas of fog late tonight into early Tuesday morning west of I-77, especially closer to the I-75 corridor. Any fog that develops should dissipate by mid-morning. A cold front approaches from the west, with sufficient forcing/moisture for a line of showers along and ahead of this cold front, reaching the I-75 corridor Tuesday afternoon. Most models have ~500 J/kg MUCAPE so have retained a slight chance of thunderstorms with this line of showers. It`s possible there could be a some gusty winds (in the 30-40 mph range) given deep layer shear of 20-25 knots and marginal instability, it`s unlikely wind gusts get any stronger than that. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... A potent shortwave trough aloft moves E`ward through the Lake Erie region and Upper OH Valley Tuesday night. At the surface, the accompanying front is expected to be located over central Lake Erie and near I-71 at sunset. The front will continue to sweep E`ward and is forecast to exit the rest of our CWA by the wee hours of Wednesday morning. Behind the front, a ridge builds from the western Great Lakes. Low-level convergence/moist ascent along the cold front are expected to trigger scattered showers and isolated thunderstorms since the ascent should release sufficient, albeit weak boundary layer CAPE, especially during the evening. Some of the thunderstorms may be strong given the potential for a moderate deep layer bulk shear/low CAPE environment in the warm sector. Behind the cold front, a NW`erly to N`erly mean low-level flow associated with strong low-level CAA and 850 mb temperatures dropping to near 6C over ~22C Lake Erie will allow a very brief period of lake-effect rain showers to occur over and generally southeast and south of the lake. However, these lake-effect rain showers will likely end by daybreak Wednesday morning as lake-induced CAPE wanes quickly via a lowering subsidence inversion and significant low-level dry air advection accompanying the aforementioned ridge. Lows are still expected to reach mainly the upper 40`s to mid 50`s around daybreak Wednesday. Fair weather is expected Wednesday through Thursday night as stabilizing subsidence accompanies the aforementioned ridge at the surface and aloft. This ridge builds from the Upper Midwest on Wednesday through Wednesday night before it begins to exit E`ward on Thursday through Thursday night. Late afternoon highs on Wednesday are still expected to reach the 60`s to near 70F as daytime heating is limited by net low-level CAA. Mainly clear sky, easing surface winds, and low humidity at/near the surface are expected to promote efficient nocturnal cooling Wednesday evening through daybreak Thursday, when lows are expected to reach mainly the 40`s to lower 50`s. Net low-level WAA begins to affect our CWA on Thursday through Thursday night as northern OH and NW PA become located along the western flank of the low-level ridge. Late afternoon highs are expected to reach the 70`s on Thursday and be followed by overnight lows reaching mainly the mid 40`s to mid 50`s around daybreak Friday. && .LONG TERM /FRIDAY THROUGH SUNDAY/... Another cold front is poised to sweep SE`ward across our CWA on Friday as another shortwave trough approaches from the Upper Midwest and vicinity. Isolated rain showers are possible due to low-level convergence/moist ascent along the front and moist isentropic ascent aloft, ahead of the shortwave trough axis. Daytime highs should reach the 70`s before the cold front passage. The shortwave trough should advance E`ward across the Lake Erie region and Upper OH Valley Friday night and be followed by a ridge aloft building from the Upper Midwest and vicinity through Saturday. At the surface, a ridge builds from the western Great Lakes and vicinity. Periodic rain showers are possible Friday night due to continued moist isentropic ascent aloft, ahead of the shortwave trough axis, and the potential for lake-effect rain showers over and generally south of Lake Erie due to NW`erly to N`erly mean low-level flow of sufficiently-cold/moist air behind the shortwave trough axis. However, any lake-effect rain showers should end by daybreak Saturday as lake-induced CAPE wanes via significant dry air advection and a lowering subsidence inversion accompanying the aforementioned ridge. These same processes are expected to yield fair weather region-wide during the day on Saturday. Overnight lows should reach mainly the mid 40`s to mid 50`s around daybreak Saturday. Late afternoon highs should reach the 60`s to near 70F on Saturday as net low-level CAA limits daytime heating. Current odds favor fair weather Saturday night through Sunday as the ridge at the surface and aloft crests E`ward over the Lake Erie region and Upper OH Valley Saturday night and then begins to exit E`ward on Sunday. However, a few rain showers are possible west of I- 71 Sunday afternoon through early evening as a trough at the surface and aloft approaches from the Upper Midwest and vicinity, and moist isentropic ascent aloft precedes the trough axis. Mainly clear sky, weak surface winds, and low humidity at/near the surface should permit efficient nocturnal cooling to occur Saturday evening through daybreak Sunday, when lows should reach mainly the 40`s to lower 50`s. Net low-level WAA along the western flank of the surface ridge and daytime heating should allow late afternoon highs to reach the upper 60`s to mid 70`s on Sunday. && .AVIATION /06Z Monday THROUGH Friday/... Fairly low confidence forecast is laid before us as rain showers are largely dissipated, leaving us with a cloud deck with variable ceilings. In the broader sense, current observations show IFR conditions to the south, with gradually improving ceilings to MVFR and VFR farther to the north. For the most part, conditions should remain relatively steady-state through the pre-dawn hours. However, model guidance show some low- level drying occurring in western Pennsylvania and should expect that to move in from the east and southeast through this morning, so KYNG and KCAK may improve before 12Z. Areawide though, should see IFR improve to MVFR, with ceilings 1500-2500ft during the late morning to mid-afternoon hours. Most of the area should lose their ceiling and scatter our between 21-03Z this evening into tonight, with most of the area starting off the night with VFR expected. Conditions become favorable for fog development, especially across Northwest Ohio and central Ohio, so we might see that starting to develop right at the end of the TAF period. East winds of 6-11 knots are expected through the day day before dropping off quickly after sunset, becoming light and variable. Outlook...Periods of non-VFR possible through Monday, becoming more scattered on Tuesday, then expanding again Tuesday night. && .MARINE... Helene`s remnant low moves generally E`ward from central KY toward the Mid-Atlantic states before dissipating tonight. A trough lingers over Lake Erie and a warm front is still expected to sweep generally N`ward across the lake tonight through Tuesday morning. Waves of 3 feet or less are expected in U.S. waters through Tuesday morning. NE`erly to E`erly winds around 5 to 15 knots through this early evening veer to S`erly tonight through Tuesday morning with the warm front passage. Note: Nocturnal cooling and abundant low-level moisture may allow stratus to expand downward to the lake surface and result in dense fog formation late this evening into Tuesday morning, especially west of Avon Point. Any fog is expected to dissipate by late morning. A cold front is still expected to sweep E`ward across Lake Erie Tuesday afternoon through the wee hours of Wednesday morning. S`erly to SW`erly winds around 5 to 15 knots ahead of the cold front veer to NW`erly and freshen to 15 to nearly 25 knots behind the front. Waves of 3 feet or less ahead of the cold front build to as large as 3 to 6 feet behind the front. Another Small Craft Advisory will likely be needed, especially east of The Islands. Behind the cold front, a ridge builds from the Upper Midwest and vicinity through Wednesday. As a result, NW`erly to N`erly winds around 15 to nearly 25 knots during the wee hours of Wednesday morning ease to 10 knots or less by midday. By sunset Wednesday evening, winds are expected to become variable in direction and ease further to around 5 knots. Accordingly, waves are expected to subside steadily to one foot or less by nightfall Wednesday evening. The light and variable winds become S`erly to SW`erly and freshen to around 5 to 10 knots Wednesday night through Thursday night as the ridge exits toward the Mid-Atlantic states. Waves of 3 feet or less are expected. Another cold front is forecast to sweep SE`ward across Lake Erie on Friday and cause the S`erly to SW`erly winds around 5 to 10 knots to veer to NW`erly to N`erly and freshen to around 10 to 15 knots. Waves are forecast to remain 3 feet or less. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...Saunders NEAR TERM...Saunders SHORT TERM...Jaszka LONG TERM...Jaszka AVIATION...Saunders MARINE...Jaszka