textproduct: Cleveland

KEY MESSAGES

1) A line of convection will develop ahead of a cold front this evening. Some strong to severe storms are possible primarily across the I-75 corridor.

2) Above average temperatures return next week with highs once again expected to climb into the upper 80s to low 90s.

DISCUSSION

KEY MESSAGE 1... As high pressure continues to drift off the Mid-Atlantic Coast today, a cold front will approach the area as a low pressure system begins to push east across the northern Great Lakes. Ahead of this cold front, a line of convection is expected to develop in the warm sector of the low over Illinois/Indiana, moving into the CWA between 7 and 8 PM EDT. Current dewpoints over Indiana in the upper 60s to low 70s mixed with the ongoing diurnally heating and theta-e advection ahead of the boundary will aid in storm development. Additionally, shear values of 20-30 knots should be able to aid in storm maintenance as they push east. The primary concern with this evening's convection is gusty winds and large hail, although there remains a non-zero tornado chance. The tricky part about the forecast over the Cleveland CWA is how far east these storms will progress and remain strong to severe. Given current model guidance placing storms in near the I-75 corridor between 7-8PM, general thinking is that corridor will see the greatest potential for severe weather before the threat rapidly decreases further east with the timing of convection becoming less diurnally favorable and instability decreasing. SPC has highlight the I-75 corridor in a Day 1 Slight Risk (2 of 5) for the storm potential and has also highlighted portions of the region upstream in a recent MCD highlighting the ongoing destabilization being observed. With any storms that develop, there is also a chance for locally heavy rainfall and due to this WPC has issued a Day 1 Marginal ERO (1 of 4) for the northwest portion of the area.

As the front progresses east tonight, scattered showers are possible along and east of I-71 but the severe threat will be minimal. This boundary should reach into far northeast Ohio and northwest Pennsylvania by Thursday morning when additional thunderstorms may occur but should remain sub-severe given the weaker environment earlier in the day.

KEY MESSAGE 2... High pressure returns to the area late Friday into Saturday and is expected to persist into early next week. This should allow for a prolonged period of dry weather over the area in addition to the gradual warming of temperatures. Highs on Saturday will remain mild in the upper 70s to low 80s before climbing into the upper 80s to low 90s for Monday and Tuesday. With dewpoints lingering in the 60s, it will be humid but overall heat indices shouldn't exceed the mid- 90s. Overnight lows Saturday night will be in the 50s before they climb into the mid to upper 60s by Tuesday night.

AVIATION /18Z Wednesday THROUGH Monday/

Scattered cumulus clouds of 4-5K are in place this afternoon. A broken line of showers and thunderstorms is expected to approach TOL towards 23Z and FDY towards 00Z. Included a 2 hour tempo for thunderstorms at those sites. Conditions could drop to IFR in heavy rain with gusts to 30-40 knots possible and isolated gusts in excess of 50 knots. The line of thunderstorms is expected to break up as it moves east so confidence is lower in the 03-06Z time frame. Terminals in NE Ohio and NW Pennsylvania can expect primarily scattered showers by late tonight. Precipitation should be limited to an hour or two at any location with VFR sct-bkn clouds around 4-7K into Thursday. Winds will tend to be southwesterly at 5-10 knots this afternoon with infrequent gusts to 20 knots. Winds will remain southwesterly tonight then shift to northwesterly with the passage of a cold front on Thursday. Outlook...Isolated to scattered thunderstorms remain possible into Thursday at YNG/ERI. Non-VFR possible in low ceilings and a few showers moving off of Lake Erie Thursday night into early Friday.

MARINE

Southwest winds will increase to 10-20 knots tonight ahead of an approaching cold front. In addition, thunderstorms may approach the western basin of Lake Erie this evening and may be strong to severe between 6-10 PM. Thunderstorms should weaken in intensity as they cross Lake Erie overnight but could still lead to erratic wind and wave conditions. Winds shift to northerly behind the front on Thursday night at 10-15 knots but are expected to decrease quickly on Friday as high pressure builds overhead. At this time we are not expected to reach Advisory criteria but choppy conditions and a moderate risk of rip currents could be possible. The trough passage across the lake could be sufficient for waterspouts to develop. Generally good marine conditions are expected for the weekend.

CLE WATCHES/WARNINGS/ADVISORIES

OH...None. PA...None. MARINE...None.