textproduct: Cleveland

WHAT HAS CHANGED

Confidence remains high on a line of showers and thunderstorms moving east through the area late this morning and afternoon, though the overall local severe threat remains rather uncertain. An environment favorable for a few embedded tornadoes and damaging winds will be in place if any stronger storms can materialize.

KEY MESSAGES

1) Showers and thunderstorms will develop ahead of a cold front late this morning and afternoon. Some storms could become strong to severe, particularly along and east of the I-71 corridor between Noon and 5 PM.

2) The next period of unsettled weather is expected Tuesday night through Wednesday, bringing periods of moderate to heavy rain and perhaps a few stronger thunderstorms.

3) A clipper system will move east through the Upper Great Lakes on Friday which could bring a rain/snow mix to the local area.

DISCUSSION

KEY MESSAGE 1...

The latest water vapor imagery reveals a strong mid-level shortwave ejecting northeast into the Midwest early this morning, with ongoing pre-frontal convection located across portions of Missouri and Illinois. The latest guidance suggests this shortwave will strengthen further through this morning, resulting in ~60 knots of 700 mb SW flow across the area by early this afternoon.

There remains some uncertainty on the evolution of this convection as it enters Ohio by around mid- morning, though do anticipate redevelopment as it encounters a more favorable environment near the I-71 corridor by late morning/early afternoon. Probabilities for instability parameters from both the REFS/HREF (such as SBCAPE > 1000 J/kg) are considerably higher than previous model runs, particularly east of the I-71 corridor. In addition, low-level hodographs also appear more favorable not only in the 0-1 km layer as they did in last night's guidance, but now also up to 3 km which tends to suggest a greater tornado potential in any stronger storms, especially those with a north to south orientation given the SW shear vectors.

The latest SPC SWODY1 categorical risk remains unchanged, though a 5% "hatched" tornado area has been introduced with this morning's update. Do think the local risk for any significant tornadoes (EF2+) is very low as the expected linear storm mode would suggest more of an transient, embedded tornado and damaging wind threat. However, this could change if storm mode begins as discrete (stand alone from other storms) and will be monitored. The timing window and location for strong to severe storms remains relatively unchanged from previous forecasts - generally along and east of the I-71 corridor between Noon and 5 PM as storms move west to east through the area.

KEY MESSAGE 2...

Guidance continues to suggest a potent upper-level trough developing across the Upper Midwest and Great Lakes Wednesday into Thursday. At the surface, a low pressure system will slide northeast through the Midwest and Eastern Great Lakes, extending a strong cold front across the area Wednesday night and ushering in a much colder air mass into the region. Probabilities remain medium to high (50 to 70%) for much of the area to see at least 1 inch of rainfall Tuesday night through Wednesday as periods of moderate to heavy rain and thunderstorms are appearing more likely. Will continue to monitor trends and potential impacts from this system over the next several days.

Above average temperatures mainly in the 60s to lower 70s will persist into Wednesday (with the brief exception of Sunday with highs in the 50s), falling into the upper 30s to low 40s behind a cold front on Thursday.

KEY MESSAGE 3... The latest guidance indicates a clipper system will move east through the Upper Great Lakes on Friday into Saturday which could bring a rain/snow mix to the local area and gusty winds. After brief high pressure on Saturday, another system may quickly develop towards the west Saturday night into Sunday.

AVIATION /12Z Saturday THROUGH Wednesday/

The main concern for aviation weather impacts will be the slight risk for strong to severe convecion to develop around midday for NWOH and through the afternoon for NEOH and NWPA. We tried to highlight the timing for this broken line of strong convection with 3 hour PROB30 groups from west to east across the area. Generally 16z to 19z for NWOH and 19z to 21z for NEOH and NWPA.

Conditions are starting out this morning mainly with VFR across northern Ohio and NWPA. There will be likely be drops of ceilings and visibilities with the broken lines of showers and storms ahead of the cold front later today. The actual cold front will move through this evening with some scattered showers. Conditions will become MVFR to lower end MVFR with ceilings overnight. Winds will be southerly southwesterly today 12 to 20 knots with gusts up to 25 to 30 very possible ahead of the cold front this morning through this afternoon. Winds will shift from the west tonight 8 to 12 knots tonight and the gusts will gradually relax by late evening.

Outlook...Non-VFR is possible with scattered rain showers and thunder with expected in low ceilings behind the cold front on Saturday night.

MARINE

There are a couple weather systems in the next several days that may bring some minor marine impacts to Lake Erie. The other ongoing marine weather impact on Lake Erie is the substantial ice coverage that continues to slowly decrease and break up. A cold front will approach Lake Erie this evening from west to east. Ahead of the cold front today, southerly to southwesterly winds will increase 15 to 25 knots with gusts up to 30 knots. Behind the front this evening and overnight, winds will become westerly 10 to 15 knots. The stronger wind flow over the lake today and the much warmer temperatures will help further to weaken the ice coverage and also move it around this weekend. Wave heights will be limited by the aforementioned mobile pack ice. High pressure will build into the Great Lakes Sunday into MOnday with a return of southwesterly 10 to 20 knots. The next potential weather system to bring impacts to Lake Erie will the middle of next week. Forecast model guidance indicates the potential for a deepening low pressure system and strong cold front tracking across the eastern Great Lakes region Wednesday through early Thursday.

CLE WATCHES/WARNINGS/ADVISORIES

OH...None. PA...None. MARINE...Dense Fog Advisory until 10 AM EST this morning for LEZ142>149- 162>169.