textproduct: Cleveland

WHAT HAS CHANGED

Replaced the High Wind Warning with a Wind Advisory until 8 AM as winds have been slow to subside overnight. Confidence is increasing in another wind event Sunday into Monday. Trended towards a non-diurnal temperature pattern on Sunday night with temperatures falling during the day on Monday. Raised pops and chances of snow on Tuesday.

KEY MESSAGES

1.) Windy conditions will return Sunday afternoon through Monday both ahead of and with a cold front. There is also a low potential for severe thunderstorms along the front late Sunday night into Monday morning.

2.) Temperatures fall to well below normal values on Tuesday with snow showers likely in the snowbelt. There is potential for single digit wind chills on Tuesday morning, climbing into the teens during the afternoon.

DISCUSSION

KEY MESSAGE #1: The Wind Advisory in Northeast Ohio and Northwest Pennsylvania has been extended until 8 AM as winds have been slow to subside overnight. High pressure will build overhead today and winds are expected to diminish quickly this morning.

Windy conditions appear likely again Sunday afternoon into Monday as a full latitude upper level trough deepens across the Mississippi Valley on Sunday night. Surface low pressure approaches the western Great Lakes on Sunday, with a 70 knot low level jet helping to lift a warm front rapidly north across the area on Sunday. Temperatures recover all the way back into the 60s to near 70 degrees. As the pressure gradient tightens during the afternoon, the strong wind field remains with winds of 50-60 knots aloft. Mixing depths will be critical for determining peak wind speeds which look likely to exceed 50 mph in Northwest Ohio. A Wind Advisory will likely be needed for northwest and north central Ohio where mixing heights are forecast to reach or exceed 5k. It is not out of the question that a few gusts approach warning levels but with primarily mechanical mixing, we lack a better mechanism for downward momentum transfer during the afternoon. The other location to monitor for strong winds will be towards Erie PA as the downsloping winds could also exceed 50 mph.

Mixing heights tend to decrease overnight but the low level jet ramps up once again. A Wind Advisory will likely need to be expanded to the remainder of the area. The other aspect of the forecast to consider is the potential for severe weather as the front wraps in from the west overnight. Instability looks to be extremely limited although temperatures will remain mild overnight. Dewpoints struggle to get above 50 and looks like the better instability may be cut-off closer to the Ohio River as the trough becomes negatively tilted. With that said, it may not take thunderstorms to bring down severe wind gusts along the front given the very strong wind field in place. Gusty showers may be sufficient to see wind gusts exceed 60 mph late Sunday night into early Monday morning. The Storm Prediction Center has the I-75 corridor in a Slight Risk of severe weather with a Marginal Risk extending to north central Ohio. Windy conditions continue behind the front on Monday with gusts of 40-50 mph. Confidence is increasing that a Wind Advisory will be needed Sunday afternoon through Monday for portions of the forecast area.

KEY MESSAGE #2: Temperatures plummet behind the cold front on Monday after starting the day mild. Rain along the frontal boundary could mix with snow or ice pellets before the widespread precipitation tapers off. Lows on Monday night dip all the way into the teens for some locations and struggle to recover on Tuesday with 850mb temperatures falling to - 15 to -17C. Winds will still be elevated on Tuesday morning and wind chills will start the day in the single digits. The day will remain cold with highs only reaching the mid 20s.

Mid-level wrap around moisture will accompany the upper level trough on Monday night and expect to see scattered snow showers across the area. The airmass will be cold enough that moderate instability is expected across Lake Erie and will combine with deep westerly flow across Lake Erie for snow showers to develop Monday night. Raised pops to likely Monday night and Tuesday across the snowbelt region of Northeast Ohio and Northwest Pennsylvania. The flow briefly shifts northwesterly towards Tuesday morning before the ridge building in from the southwest causes it to return to westerly again. The inland extent of snow showers is in question but some light accumulations look possible. Snow ratios are indicative of winter conditions in the 15 to 20:1 range. Will need to continue to evaluate available moisture and timing of the building ridge for early next week.

AVIATION /12Z Saturday THROUGH Wednesday/

The wind is finally diminishing from west to east across the terminals, and generally expect NW winds of 5-10 knots through the day, except for KERI and KYNG which will continue to gust to 20-30 knots at times through late morning. The winds will become E to SE this evening and tonight as a warm front approaches, and speeds will gradually increase toward sunrise Sunday morning.

Otherwise, mainly VFR is expected today and tonight. Some MVFR at KCAK and KYNG should scatter out in the next hour or two.

Outlook...Non-VFR likely to return in rain/snow showers Sunday. Non-VFR may linger in scattered rain/snow showers on Monday with lake effect snow possible Monday night into Tuesday.

MARINE

Winds will take longer to diminish this morning as the pressure gradient remains fairly tight across NE Ohio and NW PA. This combined with strong pressure rises and cold air advection will support continued elevated WNW winds of 25-35 knots in the central and eastern basins through at least 09Z before finally diminishing. Will extend the Gale Warnings through 12Z to be safe except replace them with Small Craft Advisories west of the Islands. The winds will steadily come down today, with NW winds of 5-10 knots by midday, becoming E and increasing to 15-20 knots ahead of a warm front tonight. Winds will become SSE and further increase to 20-30 knots Sunday and Sunday night as strong low pressure lifts through the western Great Lakes. Winds will then veer to W at 25-35 knots behind the trailing cold front Monday and Monday night, with W winds gradually diminishing to 15-25 knots Tuesday, so additional Small Craft and Gale headlines are likely Sunday through Tuesday. Winds will turn S at 15-20 knots by Wednesday.

CLE WATCHES/WARNINGS/ADVISORIES

OH...None. PA...None. MARINE...Small Craft Advisory until 10 AM EDT this morning for LEZ142>145. Gale Warning until 8 AM EDT this morning for LEZ146>149- 166>169.