464 FXUS61 KCLE 160616 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 116 AM EST Wed Dec 16 2020 .SYNOPSIS... High pressure across the Great Lakes region will continue to shift northeast throughout tonight. On Wednesday low pressure will approach the area from the southeast and linger through Thursday. Simultaneously, a stronger low pressure is expected to move up the East Coast through Thursday. High pressure will build over the area on Friday and persist through Saturday afternoon until the next system approaches the area from the northwest. && .NEAR TERM /THROUGH TONIGHT/... High pressure across the Great Lakes region will continue to drift northeast overnight tonight. With such dry air associated with this high, no precipitation is expected overnight. Cloudy conditions will persist through the overnight hours, which will allow for low temperatures to dip down into the mid to upper 20s across the area. On Wednesday, an upper-level trough digs southward across much of the central and eastern CONUS, supporting a pair of surface lows in the eastern United States. The stronger of these two lows is expected to track along the eastern seaboard from the Carolinas toward the Delmarva Peninsula. The weaker of the two lows should track from the Lower Ohio Valley toward West Virginia. Relatively-strong isentropic lift aided by an approaching 700 mb shortwave trough from the west and the left exit region of an upper-level jet streak will allow primarily light snow to overspread our CWA generally from southwest to northeast between about daybreak and the early afternoon. Model soundings indicate the strongest ascent will probably tend to be displaced above a cloudy dendritic snow growth zone. Thus, do not anticipate any bursts of heavy snow. Given projected vertical profiles of temperature and wet-bulb temperature, expect the precip to remain snow through the day as afternoon highs reach the low to mid 30's. Light snow should become intermittent over our CWA Wednesday night. This should occur as the aforementioned 700 mb shortwave trough translates toward New England, the strengthening coastal surface low moves toward Long Island, and the other surface low weakens further over West Virginia. The light snow may transition to freezing drizzle where the precip-producing cloud layer becomes too warm to support ice nucleation and snow production. However, latest model sounding data suggest the potential for freezing drizzle is negligible. Will let the overnight shift investigate further before deciding whether to remove freezing drizzle from the forecast. Low temperatures should mainly reach the 20's. Snowfall totals should reach a coating to 2 inches along and west of I-71. East of I-71, stronger and more persistent isentropic lift should yield snowfall totals of 2 to 4 inches, with the possibility for localized totals of 5 inches in Stark and Mahoning Counties. These two counties may need a Winter Weather Advisory. Will let the overnight shift evaluate the entire suite of 00Z/Wed model guidance before making a decision on any headlines. Of note, there will probably be a sharp west- to-east total snowfall gradient east of I-71. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... The axis of the upper level trough will be over the Great Lakes region into the Upper Ohio Valley on Thursday. Model guidance indicates we will have a shallow layer of moisture in the lower portion of the atmosphere on Thursday into Thursday night. We will have some lift along with the moisture but limited on cloud ice. We will mention in the forecast the potential for some patchy freezing drizzle along with scattered light snow showers or flurries. We are not expecting any measurable precip at this time but the potential for patchy freezing drizzle may impact roads. Weak high pressure will move in over the region by early Friday morning with quiet but cloudy weather continuing through Friday night. && .LONG TERM /SATURDAY THROUGH TUESDAY/... We will moderate temperatures slowly into the weekend with highs back in the 40s. Another fast moving upper level trough will move across the Midwest into the Ohio Valley this weekend. A cold front will also push through the region on Sunday. We will be mild enough to see scattered rain showers with this system late Saturday night into Sunday. Temperatures will not change much with this frontal passage. Long range model guidance are showing a much stronger and deeper upper level trough digging down out of Canada maybe middle of next week with an Arctic front. Stay tuned! && .AVIATION /06Z Wednesday THROUGH Sunday/... High pressure northeast of the region has allowed for dry conditions and just high clouds across the region. With east flow off Lake Erie, some lower lake effect clouds have entered near KTOL and will persist over the next several hours. The main concern for the TAF period will be after 12z as low pressure enters from the southwest and will bring non-VFR and snow across the region. Have timed in lowering ceilings and snow across all of the terminals from this morning through the end of the TAF period with most areas getting to IFR or LIFR. As low pressure departs to the east, IFR or lower ceilings will linger into Thursday. Winds will be easterly to start becoming more northeast late in the period, staying light 10 knots or less. Outlook...A mix of snow flurries, drizzle, and freezing drizzle may be accompanied by non-VFR Thursday through Thursday night. Non-VFR possible with snow and/or rain showers Saturday afternoon through Sunday. && .MARINE... Easterly to northeasterly winds will slowly increase tonight in response to a developing low pressure system south of the Ohio Valley. A Small Craft Advisory has been issued for the western portions of the near shore water late tonight through at least midday Wednesday. East to northeast winds 15 to 20 knots will develop higher waves for the near shore water on the western basin of the lake. Winds will become lighter and wave will decrease by Wednesday night into Thursday. Winds will remain somewhat light and variable Thursday through Friday morning with weak high pressure near the lake. Southerly winds will return Friday night into Saturday and increase 10 to 20 knots. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...Small Craft Advisory until 1 PM EST this afternoon for LEZ142>145. && $$ SYNOPSIS...Campbell NEAR TERM...Campbell/Jaszka SHORT TERM...Griffin LONG TERM...Griffin AVIATION...Sefcovic MARINE...Griffin