Area Forecast Discussion
Issued by NWS Cleveland, OH

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000 FXUS61 KCLE 180902 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 431 AM EDT Mon Mar 18 2024 .SYNOPSIS... A trough lingers over and near the eastern Great Lakes today, including northern Ohio and northwest Pennsylvania, before a weak ridge moves eastward across our region tonight. Another trough should overspread our region from the Upper Midwest on Tuesday through Wednesday and a cold front should sweep eastward through our region Tuesday evening through Tuesday night. A ridge should then build from the Canadian Prairies during Wednesday night through Thursday. && .NEAR TERM /THROUGH TUESDAY/...
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W`erly to NW`erly mid/upper-level flow impacts our region through tonight. Multiple shortwave troughs embedded in this flow aloft will move SE`ward over our CWA through this evening before a subtle shortwave ridge moves quickly SE`ward across our region overnight tonight. At the surface, a trough lingers over/near the eastern Great Lakes, including our CWA, before a weak ridge moves generally E`ward through our region tonight. The pattern will allow a cold air mass to remain entrenched across the eastern Great Lakes and Upper OH Valley. This afternoon`s highs should be near 35F in NW PA and the mid to upper 30`s in northern OH. Tonight`s lows should reach mainly the mid to upper 20`s around daybreak Tuesday. Surface wet-bulb temperatures are expected to be no greater than 33F with colder wet-bulb temperatures farther aloft. Thus, snow is expected to be the only precip type through tonight. Scattered to numerous lake-effect snow showers will continue to impact the NE OH/NW PA snowbelt and vicinity through tonight amidst lake surface to 850 mb temperature differences of ~14C to ~19C over ~6C Lake Erie, abundant synoptic low-level moisture, lake-induced EL`s near 7kft to 10kft above lake level, and a W`erly to WNW`erly mean low-level flow. Outside the LES, at least isolated snow showers are expected through this evening as potential instability in the lowest 1 km AGL is released by ascent accompanying low-level convergence along surface trough axes attendant to the aforementioned shortwave troughs aloft. However, limited daytime warming of the boundary layer combined with colder air farther aloft should lead to the development of weak SBCAPE/minimum SBCIN late this morning through early evening, allowing snow showers to become scattered to numerous along/near the surface trough axes. Snow showers, including the LES, are expected to be steady to heavy with visibility of 1/2 mile or less at times since hi-res model soundings indicate low-level convergence will allow strong ascent to become maximized in a cloudy DGZ about 50 mb to 100 mb deep at times. Snow accumulations through daybreak Tuesday should mainly be less than one inch, but 1-4" of snow accumulation are expected in the heaviest/most-persistent LES, especially in the colder higher terrain of the NE OH/NW PA snowbelt. These forecast snow accumulations preclude the need for a Winter WX Advisory. Of note: Given the relatively-high March sun angle, snow should struggle to accumulate along low-albedo surfaces (e.g. pavement and concrete) during daylight hours, especially when snow falls at a light rate. Mid/upper-level flow remains W`erly to NW`erly over our region on Tuesday as multiple/subtle shortwave troughs traverse our CWA. Closer to the surface, a shortwave trough at/near 850 mb approaches from the western Great Lakes as the attendant surface trough overspreads our CWA. Low-level WAA develops ahead of the shortwave trough axis and is forecast to contribute to afternoon highs reaching mainly the upper 30`s to lower 40`s in NW PA, and the lower 40`s to lower 50`s in northern OH. Thus, a W`erly gradient in high temperatures is forecast. Primarily fair weather is expected. However, lingering LES in the primary snowbelt of NE OH/NW PA is expected to shift N`ward and out of the region by the afternoon as the mean low-level flow of sufficiently-cold/moist air over/downwind of Lake Erie backs from W`erly to SW`erly ahead of the aforementioned low-level shortwave trough. However, low-level moist isentropic ascent aloft may allow isolated snow showers mixed with rain to impact far-NE OH and NW PA from roughly midday through sunset. Any additional snow accumulations are expected to be one inch or less.
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&& .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... A persistent upper level trough and northwest flow across the region will allow for continued cold temperatures and scattered snow shower chances for the middle of the week. The best snow chances throughout the period will be in the NE OH and NW PA snow belt where energy and moisture from Lake Erie along with the higher terrain of the region will help with snow chances and possible accumulations. The overall best snow time within the forecast period will be during the daytime on Wednesday with a vorticity maximum and upper level trough axis moving through the Great Lakes region to be supportive lift for snow while a push of colder air will help with instability to increase snowfall intensity. However, all of this will occur during the daytime hours and it is tough to see how of this snow will accumulate given the relatively warm surface and higher sun angle. High pressure will build into the region on Thursday and allow for a largely dry forecast. Temperatures will be cool for the first days of astronomical spring with 40s on Wednesday and 30s to near 40 on Thursday for highs. && .LONG TERM /FRIDAY THROUGH SUNDAY/... The weekend forecast will have some element of a forecast pattern change as the persistent upper trough will exit the region to the east. Another wave of the northern stream jet will dip toward the area, but it may pick up a shortwave moving through the southern stream over the Gulf Coast states. This combination should allow for a broader low pressure system to move through the eastern CONUS and bring some rain chances on Friday with some warmer temperatures toward the 50s. High pressure will build into the region with a more zonal pattern aloft, and dry weather with stagnant seasonable temperatures are expected for the weekend. && .AVIATION /06Z Monday THROUGH Friday/... W`erly to NW`erly flow aloft and embedded disturbances affect our region through 06Z/Tues. The axis of the strongest disturbance should move SE`ward across northern OH and NW PA between ~12Z and ~21Z/Mon. At the surface, a trough lingers in our region before a weak ridge builds from the western Great Lakes and vicinity after 00Z/Tues. Our regional surface winds trend WSW`erly to WNW`erly around 5-15 knots with gusts up to 20-25 knots at times, especially between ~14Z and ~22Z/Mon. Scattered to widespread low clouds with bases near 3kft to 5kft AGL persist through the TAF period. Scattered to widespread lake-effect snow showers are expected ESE of Lake Erie, in/near the snowbelt of NE OH and NW PA. Periods of isolated to scattered snow showers are expected elsewhere, especially between ~14Z and ~21Z/Mon given the passage of the aforementioned stronger disturbance and limited diurnal destabilization of the boundary layer. Brief MVFR to LIFR visibility is expected in steadier to heavy snow. Outlook...Non-VFR expected with periods of snow and/or rain this Tuesday through Friday. && .MARINE... Overall, the marine weather forecast for this week is rather poor for small craft vessels with several waves of low pressure through the region allowing for strong winds and increased waves. A trough continues to sit over the region today and a cold front will enhance westerly flow this afternoon and evening. Therefore, a Small Craft Advisory remains for all of the nearshore waters but areas east of Vermilion OH will have the advisory into Tuesday. Low pressure will move through the region on Tuesday into Wednesday with another cold front moving across the lake on Wednesday. Onshore flow will increase once again with waves responding accordingly and expect another Small Craft Advisory headline to be needed for Tuesday night through the first part of Thursday. High pressure will build into the region for Thursday to lighten winds and allow for one benign weather day on the lake. Low pressure will move through the region on Friday and promote northeast flow on the lake. Flow may not be all that strong but the unfavorable long fetch over the lake may present some choppy conditions for smaller watercraft. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. NY...None. MARINE...Small Craft Advisory until 10 AM EDT this morning for LEZ142>144. Small Craft Advisory until 5 PM EDT this afternoon for LEZ145. Small Craft Advisory until 8 PM EDT Tuesday for LEZ146>149. && $$ SYNOPSIS...Jaszka NEAR TERM...Jaszka SHORT TERM...Sefcovic LONG TERM...Sefcovic AVIATION...Jaszka MARINE...Sefcovic

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