textproduct: Cleveland

WHAT HAS CHANGED

Confidence is growing that any convection that develops will reach the I-75 between 7 and 8 PM EDT with the primary concern being gusty wind and large hail. The line is expected to weaken as it moves toward the I-71 corridor.

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 /06Z Thursday THROUGH Monday/

Scattered showers and a few isolated thunderstorms are moving across far Northeast OH and into Northwest PA early this morning, with potential brief impacts at ERI/YNG. Otherwise, a period of lower ceilings is possible this morning ahead of an approaching front. Hit this hardest at TOL/FDY where some fog is also possible, but still included at least a TEMPO for MVFR ceilings farther east. Clouds will likely rise to a SCT-BKN cumulus deck around 040-050 this afternoon. A few showers or thunderstorms may develop near YNG/CAK this afternoon before exiting to the southeast. Winds will shift west-northwest today as the cold front moves through and increase to 5-10kt, then shift more north-northeasterly tonight as a trough axis moves through. This trough may pick up enough moisture to lead to MVFR ceilings and perhaps a light shower near CLE/ERI tonight. Outlook...Non-VFR possible in low ceilings and a few showers moving off of Lake Erie into early Friday.

MARINE

A cold front is crossing the lake this morning, shifting winds to a more northwest direction. Winds of 10-15kt, briefly a bit higher, will continue through early this afternoon before briefly subsiding late this afternoon. Waves of 1 to 3 feet in the open waters in southwest wind will be pushed towards the lakeshore from Cleveland points northeast as winds shift with the front. Winds shift more north-northeast at 10-15kt tonight as a surface trough crosses the lake, building more 1 to 3 foot waves, especially over the western and central basins. Winds and waves are expected to remain a bit shy of advisory criteria, but will be large enough to make conditions unpleasant for small craft and to perhaps bring a moderate risk of rip currents to the shoreline from Cleveland points west. Northeast winds will remain brisk through a good portion of Friday before generally favorable marine conditions arrive for the weekend.

CLE WATCHES/WARNINGS/ADVISORIES

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