textproduct: Cleveland

WHAT HAS CHANGED

The Winter Weather Advisory has been expanded to include more of NE OH/NW PA with Lake, Geauga, and Ashtabula Counties under the advisory until 7 PM and Erie and Crawford Counties in PA under the advisory until 1 AM.

KEY MESSAGES

1) Lake effect snow, gusty winds, and seasonably cool temperatures expected today.

2) Windy conditions possible Tuesday afternoon.

3) A deepening trough across the eastern US will impact the area on Wednesday as an associated strong cold front pushes east across the area. This cold front will usher in below normal temperatures for the end of the week.

DISCUSSION

KEY MESSAGE 1... The Winter Weather Advisory has been expanded to include more of NE OH/NW PA with Lake, Geauga, and Ashtabula Counties under the advisory until 7 PM and Erie and Crawford Counties in PA under the advisory until 1 AM. 1 to 3 inches of snow is occurring with a band of heavy snow moving through the region and an additional 1 to 3+ inches is expected with lake effect snow this afternoon and evening. This will bring the storm total snow to 3 to 6 inches by this evening for the advisory areas.

Previous Key Message 1 Discussion... As an upper level trough shifts south and pushes east this morning, an area of light to moderate snow will move east across the area. General accumulations of 1 inch or less are expected with this push of snow. Within the heaviest bands of snow, visibilities and road conditions may quickly diminish and motorists should use caution.

By mid-morning, the trough axis will push east of the area, allowing for a surface trough to become established over the area. Winds with this trough will become more west to northwesterly, allowing for an onshore flow to develop across NEOH and NWPA. With much of Lake Erie remaining unfrozen, 850mb temperatures of -11 to -12C will allow for enough instability to develop, resulting in lake effect snow. The biggest uncertainty is in the moisture throughout the low and mid levels. Initially this morning, models suggest a push of drier air pushing over the area before mid-level level moisture returns this afternoon. As a result, expect the heaviest lake effect snow showers to develop this afternoon into the early evening. Snowfall totals with this update remain nearly the same with 1-3 inches expected across the NEOH snowbelt and Crawford County PA. Locally higher amounts of 3-5 inches is possible across Erie County PA. Lake effect snow should quickly end tonight as high pressure builds in.

In addition to the snowfall potential, gusty winds from the southwest to west will gradually shift to northwesterly by this evening. Sustained winds of 15-20 mph are expected with gusts up to 35 mph possible. The strongest wind gusts will likely be isolated to western counties where the strong portion of the LLJ will be centered and along the immediate lakeshore. In areas of snowfall, these gusty winds could result in patchy blowing snow which could further make travel hazardous. High temperatures today will be in the low to mid 30s, but with the gusty winds the apparent temperatures will feel closer to mid teens to low 20s.

KEY MESSAGE 2...

On Tuesday, a deepening low pressure system will gradually shift into the western Great Lakes region with above normal temperatures ahead of a system expected to usher in an arctic airmass. High temperatures on Tuesday are expected to climb into the low to mid 40s with Wednesday's highs likely occurring overnight Tuesday ahead of a strong cold front. This strong temperature gradient will aid in the development of a strong LLJ and the ultimate ramping up of winds from the southwest across the area on Tuesday. Sustained winds of 15-25 mph are expected with gusts up to 35-40 mph possible.

KEY MESSAGE 3...

A deepening trough digging south across the eastern US will impact the entire area on Wednesday into Thursday as an associate surface low tracks across the Great Lakes region. Ahead of a strong cold front early Wednesday, widespread rain showers are expected. As this boundary moves east, a much colder airmass will move into the area, allowing for a fairly quick transition from rain to snow. Cannot rule out some mixed precipitation or areas of snow squalls. During this transition, it will be important to watch how quickly temperatures fall for any additional hazards to become a concern, such as black ice.

There remains differences in the location and timing of this system amongst long range models which will likely impact the precipitation type and timing as well. The 2 uncertainties at this point is how fast does this low shift east as current models suggest it will slowly meander and how far south does the surface low shift towards the Ohio Valley. All models do seem to be in agreement however that a much colder airmass will bring the return of below normal temperatures to the area for the end of the week. Once this trough axis and surface low shift east, there is a potential for lake effect snow showers to occur across the snowbelt.

AVIATION /18Z Sunday THROUGH Friday/

Lake-effect snow showers will continue across much of NE Ohio and NW PA through the rest of the afternoon before slowly fading this evening. This will bring prevailing MVFR, with occasional IFR as well. The snow showers across NW and north central Ohio around KTOL, KFDY, and KMFD will be much more intermittent, but MVFR will prevail even there the rest of the afternoon. Drier air gradually works into the area tonight, with VFR returning from west to east. Chances for snow showers and MVFR will hold the longest at KERI, but they should be VFR by mid morning Monday. This will set up a break in the weather with VFR into Monday afternoon.

WNW winds of 15-20 knots will gust to 20-30 knots this afternoon before slowly diminishing to 10-15 knots tonight and turning W. Winds will become SW and quickly increase again to 15-20 knots with gusts over 20 knots Monday morning.

Outlook...Non-VFR possible in rain/snow showers Tuesday and Wednesday, with lake effect snow showers possible in NE OH and NW PA on Thursday and Friday.

MARINE

A cold front has reached the western basin early this morning and will cross the lake over the next few hours. Winds with this initial front have been underperforming and most of the lake is not even achieving Small Craft Advisory level winds, let alone gales. However, a secondary cold front will enter later this morning into the afternoon. This second front should allow for an uptick in winds with the potential for gale force winds to 35 kts for the eastern half of the lake, as winds shift to the west then northwest. With that, will maintain the current headlines, but will note that this event is underachieving and can see headlines get pulled back before the 7 PM end times.

For tonight and beyond, the windy and unsettled pattern will continue across the lake this week and believe that there will be several opportunities for additional marine headlines. A surface ridge building in tonight into Monday will bring elevated southwest winds of 20 kts and the ongoing Small Craft Advisory may need to be extended further in time. The pressure gradient with this ridge will weaken on Monday night and should allow for 10 to 15 kt winds and at least one period without a need for a marine headline. For Tuesday, a warm front will lift across the lake and elevated southwest flow of 15 to 25 kts will return and a Small Craft Advisory may be needed. A cold front will cross the lake on Wednesday and onshore flow of 15 to 20 kts will overtake the lake and allow for waves over 4 ft, possibly necessitating any Small Craft Advisories to continue. High pressure will begin entering on Thursday and allow for flow below 20 kts and waves to subside, likely allowing for a period or two without a marine headline.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Winter Weather Advisory until 7 PM EST this evening for OHZ012>014-089. PA...Winter Weather Advisory until 1 AM EST Monday for PAZ001>003. MARINE...Small Craft Advisory until 7 PM EST this evening for LEZ142- 143. Small Craft Advisory until 10 PM EST this evening for LEZ144- 145. Gale Warning until 7 PM EST this evening for LEZ146>149- 166>169.