textproduct: Cleveland

WHAT HAS CHANGED

The High Wind Warning remains in effect for most of our CWA until 8 PM this evening and until 2 AM EDT Saturday for Cuyahoga, Geauga, Lake, Ashtabula Counties in NE OH, and Erie and Crawford Counties in NW PA. A blowing dust-related Special Weather Statement has been issued for Marion, Crawford, Huron, and Erie Counties, OH and points west. This statement is in effect until 6 PM today. Recent significant drying of soil as drought persists and the strong, gusty winds will result in plumes of blowing dust through this early evening.

KEY MESSAGES

1.) A potent clipper will continue to affect our region through tonight. Multiple impacts are expected, including strong and gusty winds that will continue to result in tree and power line damage through at least this early evening.

2.) Another robust low pressure system will impact the region on Saturday night through Monday, bringing widespread precip and another round of strong winds.

DISCUSSION

KEY MESSAGE #1: Aloft, a shortwave trough and embedded mid/upper-level low wobble E'ward from near Lake Superior to southern QC through daybreak Saturday. At the surface, the potent low wobbles ENE'ward from northern Lower MI to southern QC and weakens slowly as it becomes vertically-stacked with the mid/upper-level low. The trailing cold front will sweep E'ward from NW OH through NW PA during this early afternoon through very early evening and should exit our CWA around 5 PM this evening. Low- level convergence/moist ascent along the front will continue to release weak boundary layer instability and trigger a line of multicell showers amidst moderate to strong effective bulk shear, including 925 mb flow near 50 to 60 knots. These showers should be efficient at transporting stronger flow just aloft down to the surface and contribute to damaging wind gusts that have already impacted our region. Behind the front, a ridge at the surface and aloft builds from the north-central United States through daybreak Saturday. Stabilizing subsidence accompanying the ridge will promote primarily dry weather behind the front. Strong low-level CAA behind the front will contribute to lows reaching the mid 20's to lower 30's around daybreak Saturday.

WINDS: Diurnal convective mixing of the boundary layer tapping into the aforementioned strong flow just aloft through this early evening, quick MSLP rises immediately behind the front, and steep low-level lapse rates and deep mechanical mixing of the boundary layer amidst low-level winds/CAA increasing with height for several hours behind the front will allow SW'erly to W'erly surface winds to gust up to 60 to 70 mph through this early evening. Sustained surface winds and gusts will then ease gradually the rest of this evening through daybreak Saturday as 925 mb flow eases in a generally southwest to northeast manner and the horizontal pressure gradient at the surface and aloft relaxes.

LAKE-ENHANCED/EFFECT PRECIP: Behind the cold front, a sufficiently-cold/moist low/mid-level atmospheric column, WSW'erly to WNW'erly mean low-level flow over and downwind of ~3C Lake Erie, weak lake-induced CAPE (LICAPE), and the seeder-feeder process should permit periods of lake-enhanced precip to impact the primary snowbelt as 850 mb temperatures plummet to -5C or colder most of this evening. This lake-enhanced precip should then transition to pure lake-effect precip by early Saturday morning as 850 mb temperatures drop further to near -10C and mid-level moisture plummets, allowing the seeder-feeder process to end. The lake-effect precip should end by daybreak Saturday as continued dry air advection at the surface and aloft, and stabilizing subsidence accompanying the building ridge, cause LICAPE to wane. Precip over and downwind of Lake Erie should begin as a rain/snow mix early this evening and then change quickly to snow due to the wet-bulb effect and CAA at the surface and aloft. Hi-res model soundings indicate the snow should be heavy at times this evening, when strong, maximized ascent should become collocated with a cloudy DGZ about 1 km deep. Snow accumulations of less than one inch are expected in the NE OH portion of the primary snow belt. Total snow accumulations of a coating to 3" are expected in NW PA. The greatest of these snow totals are forecast in the higher terrain of southern Erie and northern Crawford Counties.

KEY MESSAGE #2: Saturday, night, a ridge at the surface and aloft exits E'ward as a trough at the surface and aloft approaches from the northern Great Plains and vicinity and the attendant surface warm front approaches from the TN and OH Valleys. Moist isentropic ascent along the upper-reaches of the front should trigger a rain/snow mix, but mainly in the form of snow and especially over/near Lake Erie, where tropospheric moisture should be greater and deeper. Snow accumulations should be less than one inch and lows should reach mainly the mid 20's to mid 30's around midnight Sunday before temperatures moderate toward daybreak as low-level WAA strengthens. On Sunday, the trough aloft should deepen as it approaches from the northern and central Great Plains. The surface warm front will sweep N'ward through our region and be followed by a weak surface ridge nosing from the southeast and south as a surface low deepens and wobbles from the Mid-MO Valley toward the southwestern Great Lakes. Current odds favor dry weather, but a few rain showers may accompany low-level convergence/ascent along the surface warm front. Strong low- level WAA and peaks of sunshine should allow our highs to reach abnormally-warm values of the mid 50's to lower 70's.

During Sunday night through Monday night, the deepening trough aloft should overspread our region from the west. Strengthening divergence aloft and attendant MSLP falls downstream of the mid/upper-level trough axis should allow the surface low to deepen further as it tracks NE'ward from the southwestern Great Lakes to southern QC through early Monday evening and then deepen further as the low wobbles NNE'ward toward northern QC Monday night. The trailing and strong cold front should sweep E'ward through our CWA on Monday and be followed by a strong surface ridge building from the west. Periods of rain and scattered thunderstorms are expected along and ahead of the cold front due to pre-front moist isentropic ascent and low- level convergence/moist ascent along the front releasing at least weak CAPE, including elevated CAPE. Moderate to strong effective bulk shear may allow some storms to be strong to severe (e.g. see SPC's latest convective weather outlook). Abnormally-warm temperatures ahead of the cold front will tumble quickly behind the front and be followed by lows potentially as cold as the mid teens to mid 20's around daybreak Tuesday. Thus, any lingering rain associated with the upper-reaches of the cold front may change to snow before the front-related precip ends. A SW'erly to NW'erly mean low-level flow of very cold/sufficiently-moist air may allow Lake Erie lake-effect snow, heavy at times, to occur over/downwind of the ~3C lake later Monday into Tuesday. Something we will continue to monitor.

Note: the deepening low pressure system is expected to be accompanied by a potent and strengthening wind field at the surface and aloft. Advisory or warning-criteria regional surface wind gusts should occur later Sunday into Monday due to diurnal convective mixing of the boundary layer tapping into stronger flow aloft, quick MSLP rises behind the strong cold front, and deep mechanical mixing of the post-cold front boundary layer amidst steep low-level lapse rates and low-level winds/CAA increasing with height.

AVIATION /00Z Saturday THROUGH Wednesday/

Winds to gradually ease into the overnight, but high gusts 35-50kts still possible through around 03Z Saturday. Outside of the winds, TAFs are VFR except for ERI with the only cloud bases lower than FL100 at CAK, CLE, and YNG. For ERI, MVFR possible as snow showers develop later tonight. High pressure moves in for Saturday with more tranquil weather in place for the last 9 hours of the TAF, again, minus the light snow showers early on for ERI.

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

MARINE

A strong low pressure system will exit the region and extend a cold front across the lake. Winds with this system are overperforming with solid gales of 40 to 45 kts and storm force wind gusts of 50 to 60 kts. Winds will diminish this evening with gale force winds ending on Saturday morning. There could be a need for a short extension of the current gale warning before being replaced by a Small Craft advisory tonight. Low water conditions will persist over western Lake Erie through tonight with the strong winds.

High pressure will briefly build into the region on Saturday and allow for a short period of light winds. A low pressure system developing over the central United States will extend a warm front toward the lake on Saturday and increase easterly flow on Saturday night. The front will cross the lake on Sunday and strong southerly flow will overtake the lake, potentially to gale force winds by Sunday night. The low pressure system will cross the Great Lakes on Monday and extend a cold front across the lake on Monday. Winds will shift to the west and increase further, allowing for a period of higher confidence gales on Monday. High pressure will be sluggish to build in on Tuesday and elevated westerly flow will continue through Tuesday night, likely continuing any headline need.

CLE WATCHES/WARNINGS/ADVISORIES

OH...High Wind Warning until 8 PM EDT this evening for OHZ003- 006>010-017>023-027>033-036>038-047. High Wind Warning until 2 AM EDT Saturday for OHZ011>014-089. PA...High Wind Warning until 2 AM EDT Saturday for PAZ001>003. MARINE...Gale Warning until 4 AM EDT Saturday for LEZ142>149-162>169. Low Water Advisory until 4 AM EDT Saturday for LEZ142>144- 162>164.