textproduct: Cleveland

WHAT HAS CHANGED

Added patchy dense fog to the forecast along the Lake Erie shoreline this evening and to much of the area overnight.

KEY MESSAGES

1) Unsettled conditions with waves of low pressure and oscillating stationary fronts through Friday night, then a sharp cold front Saturday.

2) Period of dry weather Sunday and Monday followed by another frontal system midweek.

DISCUSSION

KEY MESSAGE 1... Patchy dense fog is occurring along the Lake Erie lakeshore where temperatures are in the 30s with flow off Lake Erie. Look for minimal improvement overnight as the rain spreads in, with visibilities improving for a period of time. Fog is likely to expand late tonight through as we see a break in showers and may see areas of dense fog return. Added at least a mention of patchy fog to the entire forecast area overnight and may need to consider increasing the coverage.

Previous discussion... Warm front is slowly drifting northward, and seeing this in temperature increases at MNN which have eclipsed the 50F mark. Expect further northward drift today, but still have a sharp delineation between the airmasses across the CWA. As the front drifts northward, expecting low level frontogenesis to follow suit, and increasing POPs through the evening and overnight period tonight. Some thunder is possible south of the boundary, but MUCAPE is overall meager and expect the bulk of this activity to stay south of the CWA. Still have forecast soundings favorable for fog tonight, but this should be inhibited overall by rain, and will leave the fog mentions as patchy. Thursday into Thursday night, expecting periodic rain and isolated to scattered thunder with the stationary boundary oscillating north and south within the CWA before finally lifting north of Lake Erie Friday when temperatures increase significantly area wide. Saturday is at least synoptically set up for convection, and will wait for this time frame to make it into the SPC forecast for the Day 3 period tonight, but with the warmer airmass and dewpoint surge into the 55-60F range, this will probably be the most likely day for thunderstorms with lower 70s possible.

KEY MESSAGE 2... After frontal passage, Sunday temperatures fall off a bit but should stay above normal, and a dry period with another warm up is expected into early next week with a quieter pattern in place, that is, without the waves of low pressure and stationary boundary. A robust frontal system is looking more and more likely sometime in the midweek time frame with potential for more thunderstorms, and then sharply colder in its wake beyond the 7 day forecast.

AVIATION /06Z Thursday THROUGH Monday/

First round of rain is spreading northeast across the area. Visibilities, which were rather low, have been improving as the rain moves in with ceilings improving to MVFR or VFR in some cases. The improvement is expected to be short lived as fog is likely to fill in as the rain ends. Confidence is higher for fog at Northwest Ohio terminals where colder air off the lake remains but could see a period of fog at most terminals later tonight. Two additional rounds of rain are expected to move west to east across the area, including between 13-22Z and then another round between 20-00Z. Thunderstorms will be possible with showers in the afternoon but confidence in coverage was not high enough to include in the TAFs at this time. If thunderstorms materialize, can not rule out isolated gusts to 40 knots.

Winds will vary based on which side of a stationary boundary they reside on with locations closer to the lake tending to be northeasterly and locations south of the front out of the south or southeast. Weak low pressure slides east across the area tomorrow with winds shifting to the west or northwest behind it.

Outlook...Occasional periods of rain through Saturday will bring additional non-VFR conditions.

MARINE

East/northeast winds 10 knots or less will continue through tonight before increasing to 10 to 20 knots as a warm front lifts north towards the lake on Thursday. Winds will diminish to less than 10 knots Thursday night and shift to the southeast on Friday, however winds will become south/southwest and increase to 10 to 20 knots as a cold front approaches from the west Friday night and Saturday. There will likely be a period of winds to 25 knots as the front crosses the lake Saturday afternoon. Southwest winds will develop as a ridge briefly builds over the lake towards the end of the weekend.

Lake Erie is still mostly ice covered, but above normal temperatures will allow ice coverage to decay over the next several days.

CLE WATCHES/WARNINGS/ADVISORIES

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