textproduct: Cleveland

WHAT HAS CHANGED

Based on trends in higher-res NWP model data initialized at 00Z/Tue or more recently, increased POP's along the expected cold front passage late this morning through late this afternoon. Please see Discussion-Key Message 2 for further details.

KEY MESSAGES

1) Primarily below-normal temperatures are expected to persist through Monday, February 9th.

2) Periods of accumulating snow are expected today and again this Thursday night through weekend.

DISCUSSION

KEY MESSAGE 1...

Net troughing aloft, associated with an abnormally-cold air mass, remains entrenched over eastern Canada. This trough will impact at least most of the eastern United States through Monday, February 9th, including northern OH and NW PA. Mainly below-normal temperatures are expected to persist in our CWA. For context, our normal highs are near 35F and normal lows are near 20F this time of year. At the surface, a ridge continues to exit toward the northeast United States before a weak cold front sweeps SE'ward through our region late this morning through late afternoon. Behind the front, another ridge builds from the north-central United States and vicinity through Wednesday night. Today's highs are expected to reach the mid to upper 20's ahead of the cold front. Amidst the low-level CAA regime behind the front, overnight lows are expected to reach mainly the single digits above 0F around daybreak Wednesday and Thursday, respectively, while daytime highs on Wednesday should reach the upper teens to lower 20's.

The ridge should exit slowly E'ward Thursday through Thursday night before an Arctic front sweeps SE'ward through our region on Friday. Low-level WAA on the backside of the ridge and ahead of the front should contribute to daytime highs reaching the 20's on Thursday. Lows near 10F to 15F Thursday evening are expected to moderate somewhat overnight amidst strengthening low-level WAA. Friday's highs should reach the upper 20's to mid 30's before the Arctic front passage. Behind the front, an Arctic ridge and associated colder air temperatures should affect our region through Monday as the core of the ridge moves from the northern Great Plains toward the Upper OH Valley and vicinity. Widespread sub-zero minimum wind chills should occur this Saturday through Monday, respectively.

KEY MESSAGE 2...

Periods of mainly light snow are expected today due to the following: weak moist isentropic ascent preceding shortwave trough axes embedded in W'erly flow aloft and the release of at least weak potential instability in the lowest ~1 km AGL via convergence/moist ascent along the above-mentioned cold front. However, recent trends in higher-res NWP model data suggest the forcing for ascent along the front will result in strong and maximized ascent in a cloud layer about 1 km thick and exhibiting temperatures of about -10C to -15C. Thus, a narrow band (i.e. brief burst) of steady to heavy snow may accompany the front. In addition, a sufficiently-cold/moist low-level air mass and the evolution of mean low-level flow should allow limited lake-effect snow (LES) to stream generally E'ward from mainly ice-covered Lake Erie and impact far-NE OH and NW PA ahead of the front. For several hours behind the front, limited LES should stream generally SE'ward across NW PA and NE OH before synoptic-scale low-level moisture plummets. Additional snow accumulations are expected to be one inch or less.

Current odds favor dry weather tonight through Thursday based on the projected weather pattern evolution at the surface and aloft mentioned in the previous key message section. During Thursday night through Friday, additional widespread snow is expected due to the following: moist isentropic ascent ahead of a SE'ward-moving shortwave trough axis aloft and the release of weak potential instability in the lowest ~1 km AGL via convergence/moist ascent along the Arctic front. This widespread snowfall should total roughly one to four inches in our CWA. Greatest totals should be focused in the higher terrain of NE OH and NW PA, where snow should be enhanced by moist NW'erly upslope flow, at and near the surface, and immediately behind the Arctic front.

During Friday night through this Sunday, periodic and scattered LES showers should target our CWA amidst a mainly NW'erly mean low-level flow of sufficiently-cold/moist air over/downwind of the ice-free waters of Lakes Michigan and Huron, and possible gaps in Lake Erie's ice cover. Given the expectation of extensive ice cover on Lake Huron and especially Lake Erie, LES intensity and amounts should be limited. Note: a shortwave trough embedded in NW'erly flow aloft may generate widespread light snow across our CWA Saturday night. Current odds favor dry weather Sunday night through Monday, amidst stabilizing subsidence accompanying the Arctic ridge.

AVIATION /12Z Tuesday THROUGH Saturday/

Ongoing light snow showers with MVFR to IFR visibilities across eastern terminals will gradually diminish through this morning. Anticipate for areawide MVFR ceilings to linger across all TAF sites through the majority of the TAF period. A cold front will move across the region this afternoon and evening bringing another push of light snow showers to terminals. Visibilities may drop to MVFR/IFR at times in these light snow showers. Southwest winds 5-10 knots this morning will turn northwest behind the cold front this afternoon/evening. Winds become light and variable as high pressure builds across the region tonight.

Outlook...Periods of non-VFR expected in low-level clouds and/or snow showers through Thursday. Non-VFR likely Thursday night into Friday as a cold front moves through the region with more snow expected.

MARINE

Lake Erie remains mostly ice covered with ice likely to expand through this weekend with below normal temperatures expected. Winds will remain light through the week with offshore flow through tonight. A front will move through on Tuesday and allow for north to northwest flow through Wednesday. A warm front will lift toward the lake on Thursday bringing light offshore flow again to the lake. A clipper system will cross the lake on Friday into Saturday. There will be a period of elevated winds on Friday with this system with 20 to 25 kts expected. Winds will then shift to the northwest behind the system with flow decreasing through the weekend.

CLE WATCHES/WARNINGS/ADVISORIES

OH...None. PA...None. MARINE...None.