textproduct: Cleveland

WHAT HAS CHANGED

No significant changes from the previous forecast package. Confidence is increasing for a few snow squalls along an arctic front later this morning and afternoon, particularly east of the I- 71 corridor.

KEY MESSAGES

1) In addition to the dangerously-cold wind chills expected today into Tuesday, confidence is increasing for a prolonged period of sub- zero wind chills beginning Friday.

2) A few snow squalls are possible along an arctic front later this morning and afternoon.

3) Periods of lake effect and clipper snows are likely throughout the week, with the most immediate impacts felt along the northeast lakeshore of Erie County, PA later this evening into Tuesday.

DISCUSSION

KEY MESSAGE 1...

An arctic front will move west to east through the region today, ushering in the coldest air mass of the season thus far, characterized by 850 mb temperatures falling to -22 to -24 degrees C. Temperatures will gradually drop throughout the day, following a non-diurnal trend behind the front. Modest 925 mb winds of 35 to 40 knots aloft will translate to occasional 35 to 45 mph wind gusts at the surface across the area, with the highest confidence for winds to reach 45 to 50 mph generally along or near the lakeshore east of Cleveland as the surface low enters Quebec and deepens. These blustery winds will also result in dangerously-cold wind chills falling as low as -15 to -20 degrees F late this evening through Tuesday morning.

In addition, confidence is increasing for another period of dangerously-cold wind chills towards the end of the week and potentially persisting into early next week with medium (40 to 50%) probabilities of wind chills falling below -15 degrees F.

KEY MESSAGE 2...

The latest radar and surface observations indicate the arctic front is located just east of the Illinois/Indiana border this morning with a few more potent snow showers or squalls embedded along the front. Confidence is low on the evolution of this line of snow showers into this morning as it enters Northwest Ohio with limited 700 mb moisture support. However, east of the I-71 corridor later this morning and afternoon, confidence is increasing for a few snow squalls along the front as the environment becomes more favorable, particularly where the overlap of 925 mb fgen, low- level CAPE, and 700 mb moisture is highest. Not anticipating these squalls to be as impactful as we saw a couple of days ago on Saturday, though expect rapid changes to visibility and potentially a quick coating of snow on area roadways.

KEY MESSAGE 3...

Lake effect snow will develop behind the arctic front late today through Tuesday, though it is expected to primarily impact western NY as boundary layer flow favors a west to southwest fetch. This lake effect band may wobble south at times, particularly late this evening and overnight as a weak trough sweeps through the Eastern Great Lakes, though confidence is low to medium-low as surface southwesterly flow becomes amplified with a building high to the southwest. To cover the uncertainty, a Winter Weather Advisory is in effect for Erie County, PA for snow totals of 2 to 5 inches combined with wind gusts up to 45 mph, though the higher-end of totals should be confined to the northeast portion of the County near the lakeshore.

Otherwise, the next system to watch will be another clipper on Wednesday into Thursday, bringing another period of widespread light snow of 1 to 2 inches across the area. Currently, any higher totals of 3 inches or more are favored closer to the NY/PA border.

AVIATION /12Z Monday THROUGH Friday/

The main concerns for aviation weather with this 12z TAF update will be in regards to scattered snow showers today causing MVFR to IFR conditions across the entire area this morning through early afternoon. MVFR ceilings and visibilities generally between 2sm and 5sm with the general light snow showers this morning. An Arctic front will move west to east across the area this morning though midday. Along and ahead of this front will be a broken line of heavier snow showers and possible snow squalls. These squalls may bring IFR to brief LIFR conditions at area airfields with visibilities dropping between 1/2sm to 1sm with the burst of heavier snow. The time window will be between 12z and 16z from west to east across northern Ohio and around 16z to 17z for ERI.

After the general light snow today, conditions will improve at most locations outside the primary snowbelt with MVFR to VFR ceilings later today through Tuesday morning. Lake effect snow will impact the ERI airfield later today through Tuesday morning with mainly MVFR ceilings and MVFR to IFR visibility between 1sm to 4sm. The better potential for greater impacts with IFR conditions due to moderate to heavy lake effect will be late this afternoon through the late evening at ERI. Winds will be gusty today from the southwest to west 15 to 25 knots with gusts up to 35 knots. The gusty winds will relax somewhat after 00z but remain from the west-southwest 10 to 15 knots tonight.

Outlook...Areawide light snow is expected on Wednesday, followed by lake effect snow impacting Northeast Ohio and Northwest Pennsylvania Wednesday night into Thursday. Areawide light snow may occur on Friday.

MARINE

Marine conditions will be very rough with unsettled weather on Lake Erie this week. There will be 3 main marine hazards that we are expecting to be have impacts on Lake Erie over the next several days. A low pressure system is tracking across the Upper Great Lakes this morning with an Arctic cold front that will sweep across Lake Erie by midday. Strong southwesterly to westerly winds will increase 30 to 40 knots with gusts up to 45 knots over Lake Erie today behind the cold front. In the open water that remain ice free, waves will build 10 to 15 feet today. Areas that are closer to the nearshore marine zones will be 5 to 9 feet that are ice free. There is currently ice along the entire southshore of Lake Erie which extends outward from the immediate lakeshore from Cleveland to northwest Pennsylvania. Most of the western basin of Lake Erie west of Cleveland and around the islands is now ice covered with limited open water.

Gale warnings go into effect early this morning and continue into the evening and or overnight hours. The Gale warnings will slowly be taken down from west to east across Lake Erie as the winds slightly decrease below that threshold. West to southwest winds will remain elevated 20 to 30 knots late tonight through the middle of the week. Wave heights will also remain elevated and very rough through almost the entire week. There is a Heavy Freezing Spray Warning today though much of Tuesday for the central and eastern basin of Lake Erie. With the combination of strong gusty winds and Arctic cold temperatures, heavy freezing spray will be likely in the open waters of Lake Erie. The other marine concern is for the western basin from the Lake Erie Islands to the Toledo area in regards to water levels that will likely fall today below the critical mark for safe marine navigation. There is the potential for4 the water levels to fall several feet below the critical mark. But there is some uncertainty on how this will play out due to most of the lake is ice covered in the western basin. The lowest water levels will occur this afternoon into the early evening before they slowly rebound back upward later tonight.

There will be another weather system Wednesday into Thursday that will bring an increase in west to southwest winds nearing Gales potentially. During that timeframe of stronger winds, water levels in the western basin may drop again to near or below the critical mark. Strong gusty winds and very rough conditions will continue through the end of this week.

An Arctic airmass will continue to flow over the Great Lakes and over Lake Erie for much of this week. The coldest temperatures will arrive late this weekend through next weekend which will contribute in ice formation. Generally moderate ice growth is expected across Lake Erie this week into the weekend, with the limiting factor to rapid ice growth being strong winds. This will also likely cause significant drifting of existing weaker ice.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Cold Weather Advisory from 1 PM this afternoon to noon EST Tuesday for OHZ003-006>009-017>019-027>029-036-037. Cold Weather Advisory from 7 PM this evening to noon EST Tuesday for OHZ010>014-020>023-030>033-038-047-089. Wind Advisory from 10 AM this morning to 7 PM EST this evening for OHZ011-012-014-089. PA...Cold Weather Advisory from 7 PM this evening to noon EST Tuesday for PAZ001>003. Wind Advisory from 10 AM this morning to 7 PM EST this evening for PAZ001-002. Winter Weather Advisory from 10 AM this morning to 7 AM EST Tuesday for PAZ001-002. MARINE...Gale Warning until 7 PM EST this evening for LEZ142>145- 162>165. Low Water Advisory until 10 PM EST this evening for LEZ142>144- 162>164. Small Craft Advisory until 7 AM EST this morning for LEZ146>149. Gale Warning until 1 AM EST Tuesday for LEZ146>149-166>169. Heavy Freezing Spray Warning until 1 PM EST Tuesday for LEZ146>149-166>169.