textproduct: Cleveland

WHAT HAS CHANGED

Confidence is increasing on accumulating snowfall with potential travel impacts from Wednesday afternoon to Thursday evening. Temperatures are trending colder this weekend with single digit lows and overnight wind chills below zero becoming more likely.

KEY MESSAGES

1) Above normal temperatures and breezy conditions are expected on Tuesday.

2) Rain will transition to snow Wednesday afternoon and evening, allowing for travel impacts to the evening commute. Hazardous winter conditions will continue through Thursday evening with additional widespread snow accumulation.

3) Weekend weather pattern continues to trend colder with more snow possible.

DISCUSSION

KEY MESSAGE 1... After a relatively quiet weather day today with high pressure extending into the region, a warm front will enter for Tuesday. This front will allow for temperatures to warm back into the 40s. In the warm sector of this system, some amount of a 40 to 50 kt low level jet will mix down to the surface. This will allow for southwest wind gusts of 35 to 40 mph during the afternoon hours. Overall, impacts from the wind should be limited and conditions should stay below Wind Advisory limits.

KEY MESSAGE 2... The main story for the forecast this morning will be a strong cold front that will enter the area on Wednesday. A large upper trough with several shortwaves embedded will enter the Great Lakes region, starting Tuesday evening. The initial wave will allow for rain across the area Tuesday night into Wednesday. The main upper level wave will support a strong cold front on Wednesday afternoon and evening and will allow for an abrupt transition from rain to snow, likely in time for the Wednesday evening commute. The combination of the sudden change to snow with the potential for half inch to one inch snowfall rates, temperatures plunging from the lower 40s to upper 20s, and surface/pavement temperatures likely starting above freezing to quickly falling below freezing could allow for hazardous travel conditions across the region.

Behind this initial cold frontal passage, the upper trough will slow and consolidate into a closed low over the area, allowing for low pressure to develop over the Central Appalachians Wednesday night. The deformation zone of this low will be in close proximity of the eastern forecast area and will bear some watching, as any westward deviation could become problematic for a period of heavy snow on Wednesday night into Thursday. Regardless of the evolution of this low, the upper low will allow for a reinforcing cold front through the area, which should allow for another round of snow for the whole area on Wednesday night into Thursday with additional lake enhancement for the northern half of the area. Confidence is increasing in several inches of snow for the entire area from Wednesday afternoon through Thursday evening with the need for at least a Winter Weather Advisory increasing with every forecast cycle.

KEY MESSAGE 3... After a brief break in action on Friday, another system will enter for the weekend. This system will have the support of an upper trough that will originate over northern Canada and carry south some Arctic air into the Great Lakes region. The timing of the main low pressure system will be on Saturday with periods of snow that will then transition into lake effect snow on Sunday. There is low confidence on total snowfall in the region right now but at least light accumulations are likely everywhere with higher amounts in NE OH/NW PA. The bigger story and the higher confidence portion of this system will be temperatures and wind chills. Highs on Sunday and Monday will barely touch the 20 degree mark and low temperatures on Saturday night will be in the teens with single digits Sunday and Monday nights. Winds of 15 to 25 mph with higher gusts will lead to wind chills in the single digits during the day and below zero overnight. Early trends in the forecast are closer toward Cold Weather headlines.

AVIATION /12Z Monday THROUGH Friday/

A mix bag of MVFR and VFR conditions will gradually improve to all VFR throughout this morning as high pressure builds over the area. This high will allow for dry and breezy conditions across the area today. Southwest winds of 12-15 knots with gusts up to 25 knots are possible through 00Z before calming to 5-11 knots overnight.

Outlook...Non-VFR becoming more likely in rain Tuesday night into Wednesday. Non-VFR will continue into Thursday as rain transitions to snow late Wednesday. Non-VFR may return in snow showers on Friday.

MARINE

Unsettled marine conditions are expected throughout this week as an active weather pattern continues to influence the region. Today, high pressure centered near the Gulf Coast will gradually nudge north towards the region. This couple with a low pressure moving east across northern Canada will allow for an increased gradient across Lake Erie which will allow southwest winds to increase to 20- 30 knots across Lake Erie. Models have trended up with winds across the eastern basin with sustained gale force winds expected through this afternoon. Given the hazardous marine conditions, the entire lakeshore has a Small Craft Advisory through this afternoon with the eastern basin being upgraded to a Gale Warning beginning at 7AM local time. Winds will quickly weaken after 7PM tonight to be some the southwest at 10-20 knots.

These calmer conditions will be short lived as another robust low pressure system moves across the northern Great Lakes Tuesday into Wednesday. This system will initially increase southwest winds to 20- 30 knots on Tuesday afternoon with a brief lull early Wednesday morning as the trough axis shifts east. Then, by Wednesday afternoon winds will back behind a cold front and once again ramp up to be sustained from the north-northwest at 20-30 knots. This period of onshore flow will allow for the larger waves to develop with waves up to 8 feet possible across the central basin. This period will likely need additional marine headlines. By Friday, winds continue to weaken before another potential robust system moves through this weekend.

CLE WATCHES/WARNINGS/ADVISORIES

OH...None. PA...None. MARINE...Small Craft Advisory until 1 PM EST this afternoon for LEZ142- 143. Small Craft Advisory until 7 PM EST this evening for LEZ144>148. Small Craft Advisory until 7 AM EST this morning for LEZ149. Gale Warning until 7 PM EST this evening for LEZ149-169.