Area Forecast Discussion
Issued by NWS Cleveland, OH

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000 FXUS61 KCLE 210552 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 1252 AM EST Tue Nov 21 2017 .SYNOPSIS... High pressure over the Tennessee River Valley will move off the mid Atlantic Coast tonight. Tuesday, low pressure will move east across Ontario. A cold front extending south from the low will move across the region during Tuesday afternoon and evening. High pressure will then take control of the region on Wednesday. && .NEAR TERM /THROUGH TODAY/... Made some adjustments to temps and sky conditions. Temps shouldn`t drop much more from current readings given winds. Previous...High pressure over the Tennessee Valley will dominate weather across the region tonight. Tuesday, the high will move off the mid Atlantic Coast allowing low pressure to move east across Ontario. Tuesday should be fairly windy however as the pressure gradient between the two systems tightens. Southwest winds should increase to around 20 and 25 mph with gusts into the 30s. At this point believe we will remain below wind advisory criteria. Late Tuesday afternoon the cold front associated with the low will move nw to se across the area reaching near a KCLE-KMFD line by 00Z Wed. Will keep forecast dry Tuesday through the morning. For the afternoon models have slight differences with the GFS bringing precip into the area while the NAM is just a bit drier, developing precip mostly after 00Z. Will bring in low chance pops northwest for the last couple hours of the afternoon and a slight chance elsewhere but believe the bulk of the precip will come after 00Z as flow off lake erie adds enhancement. For tuesday night will have chance pops outside of the lake effect areas. For northeast OH and nwrn PA will have pops increase to likely/categorical by 06z with highest pops inland nwrn PA. While 850mb temps drop off to -10C by 12Z Wed, dry air also moves in quickly and inversion is quite low so do not expect a large lake effect threat. Given the dry air will taper pops quickly as moisture pulls out. As for accums will have an inch or two at this point. && .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... An upper level trough will rotate east across the local area by Wednesday. Another cold front will move southeast across the area early morning Wednesday ushering in another round of cold air to the forecast area. Flow will briefly become well aligned with minimal instability to support some lake effect snow showers Wednesday morning over the northeast. Otherwise, fair weather will prevail across the rest of the forecast area Wednesday. As cold front shifts east, cold pool of air will move east of the area with it as high pressure builds northeast into the forecast area for Thursday and Friday. Fair weather will be the rule under the high pressure center Thursday and Friday. As cold air advection retreats northeast of the area, a warm air advection pattern will develop on the northern side of the high pressure. We should see temperatures climb out of the 30s for highs Wednesday into the 40s by Friday. Lows and 850 mb temperatures will be cold enough to support the snow in the northeast Wednesday morning. Overnight lows will be in the 20s Thursday and Friday. && .LONG TERM /FRIDAY THROUGH MONDAY/... A strong, quick moving cold front will drop southeast across the area Friday night, bringing rain chances to the area. Will hold with high likely pops maxed out across the northeast part of the forecast area. Temps will turn colder starting Saturday as a deep upper trough digs across the Great Lakes region, with 850mb temps dropping to around -10C by Saturday evening. This will also usher in a prolonged period of lake effect precipitation, transitioning from a mix to all snow Saturday night. On and off lake effect snow is expected from Saturday night through the day on Monday, at least. The flow is expected to become more southerly with high pressure building into the area by Monday night, effectively turning off the lake effect machine. It`s pretty far out for details, but chances for accumulations look pretty good for the snow belt. There is ample synoptic moisture up through about 850mb, little directional shear, moist DGZ, and lake surface-850mb delta T values approaching 20C, with subsequent inversion heights topping out around 13kft. However, the lowest 2-3kft look sub-saturated, with the best lift centered below optimal snow growth. This will be something that will need to be monitored throughout the week for specifics, but there isn`t much more to glean at this point other than a decent shot at accumulations for the snow belt Sunday through Monday. After slightly above normal temperatures Friday night into Saturday, temperatures will be below normal through the remainder of the period. && .AVIATION /06Z Tuesday THROUGH Saturday/...
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Strong low level jet moving across the region. This has allowed for a decent setup for low level wind shear. Have placed this mention at all TAF sites with surface wind gusts under 25 knots. Looks like southwesterly winds around 2000 feet will be 45 to maybe 50 knots. The gusty winds will continue through the afternoon with several locations seeing wind gusts touch 30 to 35 knots. Winds shift to the northwest in the wake of the cold front and decrease slightly. Otherwise we will await the arrival of a cold front. Current thinking is that the cold front crosses the area during the evening with a period of showers. The better chances of showers will be downwind of Lake Erie from Cleveland to Erie. MVFR conditions are expected with the showers. The MVFR conditions will persist into the overnight hours as temperatures drop. A short period of lake effect snow will be possible across the snowbelt of NE OH/NW PA. Away from this area ceilings will slowly lift and dissipate. OUTLOOK...Non-VFR conditions will likely linger across NE OH/NW PA into Wednesday evening. The next chance for non-VFR conditionslooks like it will arrive with a cold front on Saturday.
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&& .MARINE... Winds will increase once again on the lake tonight out of the southwest. Will go ahead and hoist small craft advisory for the western basin for tonight even though warm air advection will take place over the lake. Highest waves will likely be in the 4 to 5 mile from shore area in the nearshore waters. Winds on the lake will be gusty through Tuesday night when the cold front passes through the area. Flow will become northwest Wednesday and gradually diminish to light west and southwest Wednesday night. Southwest flow will return and increase with the tightening gradient associated with the high pressure to 15 to 20 knots. A small craft advisory will likely be needed later in the week into the weekend. && .CLE WATCHES/WARNINGS/ADVISORIES...
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OH...None. PA...None. MARINE...Small Craft Advisory until 3 PM EST Wednesday for LEZ145>149. Small Craft Advisory until 10 AM EST this morning for LEZ142>144.
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&& $$ SYNOPSIS... NEAR TERM...TK/Kubina SHORT TERM...Lombardy LONG TERM...Lombardy AVIATION...Mullen MARINE...Lombardy

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