textproduct: Cleveland

WHAT HAS CHANGED

No major changes were made to the forecast with this full update besides increasing winds and gusts for most of Friday through Friday night. This is when a deepening clipper-type low pressure system should impact our area. Confidence continues to increase that the clipper will generate widespread light to moderate accumulating snow in northern OH and NW PA this Thursday night through Friday.

KEY MESSAGES

1.) Primarily below-normal temperatures are expected through this Monday before temperatures potentially rebound to near-normal values on Tuesday, February 10th.

2.) Periods of snow are expected this morning and again this Thursday night through upcoming weekend.

3.) Behind an Arctic front, gusty northwesterly winds are expected on Friday into Friday night.

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, as the S'ward extent of the trough fluctuates. 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 builds from the north- central United States and vicinity through tonight. Amidst the low-level CAA regime behind a recent cold front passage, highs this afternoon are expected to reach the upper teens to lower 20's. Overnight lows are expected to reach mainly the single digits above 0F around daybreak Thursday.

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 mainly the lower to mid 20's on Thursday. During Thursday evening, lows near 10F to 15F are expected in NW PA and NE OH, while lows mainly near 15F to 20F are expected farther west in our CWA. After midnight Thursday night, readings are expected to begin to moderate amidst strengthening low-level WAA. Friday's highs are expected to reach the mid 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 night as the core of the ridge moves from the northern Great Plains toward New England. Widespread sub-zero minimum wind chills should occur this Saturday through Monday, respectively. The coldest of these wind chills (-10F to -20F) should occur Saturday morning and may prompt a Cold Weather Advisory for at least parts of our CWA. On Tuesday, the surface ridge should continue to exit E'ward as a ridge aloft, associated with a warmer air mass, overspreads our region from the west. Accordingly, our latest forecast calls for afternoon highs to reach the lower to upper 30's.

KEY MESSAGE 2... Latest surface obs and radar data as of 2:30 AM EST indicate snow flurries are lingering across much of our CWA. These appear to simply be the result of mixed-phase stratocumuli that are just thick enough to support very light snow production. As a lowering subsidence inversion accompanies the aforementioned, building surface ridge, expect the stratocumuli to thin enough to no longer support snow production by midday today. No more than a trace of snow accumulation is expected from these flurries.

Current odds favor dry weather the rest of today 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, widespread snow, steady at times, is expected due to the following: moist isentropic ascent ahead of a SE'ward-moving shortwave trough axis aloft and the release of at least weak potential instability in the lowest ~1 km AGL via convergence/moist ascent along the Arctic front. The front should sweep SE'ward through our region during the late morning through early evening hours of Friday. As higher-res NWP model data become available for this portion of our official forecast, will have to monitor model sounding data for a potential burst of heavy snow and/or graupel along the front. The widespread snowfall is still expected to total roughly one to four inches in our CWA. The greatest totals should be focused in the higher terrain of NE OH and NW PA. This is where snow should be enhanced by moist NW'erly upslope flow for as long as several hours behind the Arctic front and before low-level dry air advection begins in earnest.

During Friday night through this Sunday, periodic and scattered LES showers should target our CWA amidst a NW'erly to N'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 into Sunday. Current odds favor dry weather Sunday night through Tuesday amidst stabilizing subsidence accompanying the aforementioned ridge.

KEY MESSAGE 3... NW'erly surface winds are expected to be around 20 mph sustained and gust up to 30 to 40 mph behind Friday's Arctic front passage. Steep low-level lapse rates and rather deep mechanical mixing of the boundary layer amidst low-level winds and CAA increasing with height will promote these gusty winds. Wind gusts should begin to subside during the wee hours of Saturday morning and ease significantly by daybreak amidst a relaxing MSLP gradient. Trends in NWP model guidance will continue to be monitored for the potential need of a Wind Advisory (peak gust criteria: 46-57 mph). Note: these NW'erly surface winds should result in some blowing and drifting of freshly-fallen snow.

AVIATION /12Z Wednesday THROUGH Sunday/

Patchy MVFR stratus remains with some pockets of VFR in clear skies this morning. Anticipate for any clearing this morning to fill back in with MVFR ceilings this afternoon as expansive cloud cover remains across the Great Lakes region in the wake of a cold front.

As a ridge builds east this evening there will be a brief window of VFR returning to all TAF sites before MVFR returns in low stratus and patchy BR late tonight/early Thursday morning. Winds remain light and variable through the TAF period.

Outlook...Periods of non-VFR expected in low-level clouds and/or snow showers through Thursday. Non-VFR likely Thursday night into Friday evening as a clipper brings snow areawide. Northwest wind gusts of 30-35 knots will be possible Friday evening.

MARINE

Lake Erie remains mostly ice covered and will continue to expand during a prolonged period of below normal temperatures through this weekend. A ridge of high pressure builds across the region today through Thursday allowing for light northwesterly flow over the lake. Winds turn westerly to southwesterly while increasing to 10-15 knots Thursday into early Friday ahead of a clipper system. Winds turn northwesterly and increase to 20-30 knots Friday evening through early Saturday as the system pushes to the east. Another area of high pressure builds overhead Saturday into early next week allowing for winds to diminish to 5-10 knots.

CLE WATCHES/WARNINGS/ADVISORIES

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