787 FXUS61 KCLE 260926 AAD AFDCLE Area Forecast Discussion...UPDATED National Weather Service Cleveland OH 426 AM EST Thu Nov 26 2020 .SYNOPSIS... A low pressure system will depart the eastern Great Lakes region later today. High pressure will build into the Ohio Valley for the end of the week. A potential larger and stronger low pressure system may develop and bring unsettled weather by early next week across the region. && .NEAR TERM /THROUGH FRIDAY/... The weather pattern for the rest of the week will be fairly quiet compared to what potentially may lie ahead for next week. A low pressure system is moving out of local area through the eastern Great Lakes into the New England region. We still have some showers moving across Lake Erie and the lakeshore areas from the back side of the exiting storm system this morning. The rain showers will end for most of the area later this morning but may linger downwind of Lake Erie through tonight, eventually ending early on Friday. Weak high pressure will be building across the Ohio Valley for the end of the week. Considerable cloudiness will hang on across the region through Friday. Temperatures will continue to be above average through tomorrow. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... An elongated area of vorticity with an upper-level trough and associated surface cold front will make its way east across the area Friday night. This will provide just enough moisture for some light, scattered showers for northeast Ohio and northwest Pennsylvania Friday night. Drier air will build in with surface high pressure on Saturday and Sunday with decreasing cloud cover on Saturday and near normal temperatures. Clear/sunny skies are expected Saturday night and Sunday. A chilly start Sunday morning will give way to slightly above normal temperatures Sunday afternoon. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... The big weather story of the week will be with a storm system that impacts the region in the form of widespread rain, windy conditions, and the potential for accumulating snow. An upper-level cut-off low that moseys across the southern CONUS over the weekend will be picked up by a northern stream upper-level trough, causing the cut-off low to lift north towards the Great Lakes region Sunday night into Monday. This results in a large cut- off low developing over the Great Lakes, and perhaps much of the eastern 1/3 of the CONUS, on Tuesday and Wednesday. At the surface, a low develops across the deep south and rapidly deepens as it lifts north towards the Great Lakes region on Sunday night and Monday. Most of the major model guidance have this low deepening to around 990-995 mb by Monday afternoon. This surface low is expected to meander and wobble around the Great Lakes and Ontario through Tuesday and Wednesday. Confidence continues to increase in widespread rain occurring with this low beginning Sunday night and lasting through much of the day Monday. Have much of the area in at least 60% on Monday while starting to introduce 80% PoP for northeast Ohio and northwest Pennsylvania. Confidence in strong, gusty winds is increasing as well, as model guidance continues to project a rather strong low, though there is still a great deal of uncertainty with the evolution of the wind field. At some point Monday night into Tuesday, cold air from the northern Great Plains and Canadian prairies will be advected into the region, resulting in a changeover from rain to snow for most areas. Accumulating snow will be most likely Tuesday and Tuesday night. While there is still uncertainty with exact low track/strength, surface temperatures, and QPF amounts, confidence continues to increase with each forecast cycle in the possibility for widespread accumulating snow. The National Blend of Models (NBM) has started indicate an area with a 50% chance or greater of 4 inches of snow. The Weather Prediction Center has also increased their probabilities with this forecast run, with a large area of 30-50% probability of exceeding 0.25 inch liquid equivalent of snow. Of course being five days out, there is uncertainty with the details of this system, including exact snow amounts, location of heaviest snow, general snow rates, timing, etc. However, confidence is increasing in accumulating snow of at least a few inches, given general model agreement of synoptic scale conditions and data from ensemble guidance. This means you'll want to continue to keep an eye on the forecast for Monday through Wednesday and begin prepping for the possibility for accumulating snow, e.g. make sure you have that snow blower ready to go! && .AVIATION /06Z Thursday THROUGH Monday/... Low pressure will track northeast across the eastern Great Lakes region through the morning hours. MVFR ceilings will move into the area on the back side of the low pressure system early this morning. There will be IFR ceilings closer to the airports near the lakeshore through late morning. Slow improvement in ceilings expected after 18Z through the end of the period. Winds will be veering westerly behind the low for the TAF period. Outlook...Non-VFR may linger across Northeast Ohio and Northwest Pennsylvania through midday Friday. Non-VFR likely Monday. && .MARINE... An occluded low will continue to move east across the east Great Lakes today towards the New England coast by tonight. West-southwest winds of around 20 knots will develop this morning as this low departs to the east of Lake Erie, resulting in the issuance of a Small Craft Advisory for the eastern half of Lake Erie nearshore waters through this evening. Southwest winds will decrease to 15 knots tonight, briefly shifting to out of the northwest Friday night with the passage of a cold front. Winds become southwest once again on Saturday and Sunday as high pressure builds south of Lake Erie. A low pressure system is expected to impact the region starting Monday and through much of next week. How exactly that plays out with regard to winds and waves on Lake Erie is still uncertain at this time, though there is the potential for strong winds perhaps up to gale-force on Monday with northeast winds and again with west to southwest winds on Tuesday and Wednesday. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...Small Craft Advisory from 7 AM this morning to 10 PM EST this evening for LEZ147>149. && $$ SYNOPSIS...Griffin NEAR TERM...Griffin SHORT TERM...Saunders LONG TERM...Saunders AVIATION...Griffin MARINE...Saunders