Area Forecast Discussion
Issued by NWS Cleveland, OH

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000 FXUS61 KCLE 181443 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 943 AM EST Sat Jan 18 2020 .SYNOPSIS... Low pressure will move east across the central Great Lakes today. High pressure from the northern Great Plains and upper Midwest will build southeast to the Ohio Valley Monday through Wednesday, lingering over the mid-Atlantic Thursday and Friday. Low pressure will move northeast toward the central Great Lakes Friday night. A warm front will lift north across the area Friday night followed by a cold front Saturday. && .NEAR TERM /THROUGH SUNDAY/... Precipitation continues to transition over from snow to sleet and freezing rain, and to rain once surface temperatures rise to above freezing. Will be looking to expire the Winter Weather Advisory as we transition to all rain. Once most of the current Winter Weather Advisory goes, we will be looking to address the expected lake effect snow tonight and tomorrow. Previous Discussion... Mixed bag of precipitation continues across the local area at this time. Biggest surge of precipitation appears to be with the warm front as it lifts northeast. Latest observations indicate freezing line is across the central portions of Ohio and is showing signs of beginning to lift north and northeast at this time. Timing of the warmer air and the freezing line appears it will begin to move into the local area around sunrise and lift northeast across the area during the morning as the 850 MB jet maximum pushes into the area. This will help to warm temperatures at the surface today into the 40s for highs. Snow amounts are expected to be on the lighter side due to the mixed precipitation this morning. Then, as whole package of precipitation (rain) moves northeast across the area, expecting back edge to move east of the area overnight tonight. As cold air advection returns behind the cold front tonight, the rain will transition over to snow mainly in the eastern portions of the forecast area. A return back to fair weather will result in the west later tonight into Sunday. Cold air advection overnight tonight will cause surface temperatures to drop into the teens and begin to set-up some lake effect snow heading into Sunday. Lake effect snow potential looks good but a lot of factors have the potential to prevent widespread areas from reaching warning criteria for snow. First is the best flow with the longest Lake Erie fetch occurs during the day Sunday when the inversion is relatively low and instability is conditional at best. As the instability becomes a bit more favorable, wind flow becomes less favorable in direction and becomes more northwest to northerly by evening. The firehose effect of spreading the snow across a larger area rather than a concentrated area will likely keep widespread areas from seeing significant snow accumulations. Therefore, since confidence is low in reaching warning criteria at this time, will hold off on issuing a watch for the lake effect snow. We may wind up with just advisory criteria when it is all said and done. Highs on Sunday will only max out in the lower to middle 20s in the cold air advection. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... A secondary push of Arctic air with a surface trough will move across the area Sunday evening which will shift the surface flow from westerly to more northwesterly Sunday night and eventually more northerly by Monday morning. 850 mb temperatures will be around -12C to -15C if not a little colder. The surface trough and wind shift Sunday evening will have some convergence along that boundary and will likely see a band of snow with the wind shift push across much of the area early evening. The Lake Effect snow will be in prime time mode Sunday night and will become more oriented with the northwest to northerly flow impacting both the primary and secondary Snowbelt areas as well as the higher terrain areas. We will need to monitor a potential Lake Huron connection Sunday night into Monday morning possibly impacting the Monday morning rush hour for the Cleveland metro area. The surface flow shifts again to more west-northwest by late Monday afternoon and night with the primary focus shifting back to the primary Snowbelt areas. Another weak surface convergence feature showing up in some of the models may have another slight uptick in the lake effect bands Monday evening. The lake effect will slowly begin to decrease by midday or the afternoon on Tuesday as winds become westerly late on Tuesday. A light southwest surface flow returns by Tuesday night. Overall, there will be the potential for moderate to locally significant snowfall amounts in the Snowbelt over the 2 to 3 day lake effect event. There still remains uncertainty on which areas may see the highest totals and exact amounts with the possible "firehose" effect of the movement of the bands and squalls. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... Southerly winds will bring a moderation in temperatures by Wednesday through the end of the week. Temperatures will be back to above average for the end of next week with 40s returning. The next storm system to impact the region will be towards the end of next week with widespread rainfall this time around. && .AVIATION /12Z Saturday THROUGH Wednesday/... Low pressure and associated warm front will continue to move northeast and then east this morning. A mixed bag of precipitation can be expected through this morning and then warmer air will move northeast into the region and change the precipitation over to all rain. Deteriorated ceilings and visibilities will continue across the area over the next several hours with improvement taking place into tonight. Lingering lake effect snow will begin to develop later tonight in the northeast. .OUTLOOK...Widespread non-VFR returns over the weekend with rain and snow. && .MARINE... Conditions will deteriorate today and tonight on the lake with southerly winds and waves increasing this morning through the afternoon. Southerly winds will increase to 15 to 25 knots and gusts up to 35 knots by midday and afternoon. A deepening area of low pressure will move across the Great Lakes into southern Ontario this evening and overnight. Southwesterly Gales of 35 to 40 knots with gusts to up 50 knots will be likely on the lake late this afternoon through Sunday morning. As the low pressure system moves away from the area Sunday, cold air advection will come across the lake on westerly winds 20 to 30 knots on Sunday and higher waves. Critical low water levels will be likely on the western basin of the lake tonight into Sunday and an advisory will likely be needed in future forecast updates. With much colder air moving in late tonight through early next week, freezing spray will be a concern as well. With strong westerly winds, there will be some concern for higher waves and erosion along the lakeshore later today through Sunday. A surface trough will shift the winds to more northwesterly 15 to 25 knots Sunday evening through Monday. Winds start to decrease and become westerly to southwesterly by Tuesday into Wednesday with lower wave heights. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...Winter Weather Advisory until 3 PM EST this afternoon for OHZ009>014-019>023-028>033-036>038-047-089. Wind Advisory from 6 PM this evening to 10 AM EST Sunday for OHZ012-089. Wind Advisory from 3 PM this afternoon to 7 AM EST Sunday for OHZ007>010. Wind Advisory from 3 PM this afternoon to 10 AM EST Sunday for OHZ011. Winter Weather Advisory until 1 PM EST this afternoon for OHZ003-006>008-017-018-027. PA...Wind Advisory from 6 PM this evening to 10 AM EST Sunday for PAZ001. Winter Weather Advisory until 10 PM EST this evening for PAZ001>003. MARINE...Small Craft Advisory until 3 PM EST this afternoon for LEZ142>146. Gale Warning from 3 PM this afternoon to 7 AM EST Sunday for LEZ142>145-162>165. Small Craft Advisory until 6 PM EST this evening for LEZ147>149. Gale Warning from 6 PM this evening to 10 AM EST Sunday for LEZ147>149-167>169. Gale Warning from 3 PM this afternoon to 10 AM EST Sunday for LEZ146-166. && $$ SYNOPSIS...Lombardy NEAR TERM...Lombardy/Saunders SHORT TERM...Griffin LONG TERM...Griffin AVIATION...Lombardy MARINE...Griffin

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