textproduct: Cleveland

WHAT HAS CHANGED

Shower onset on Saturday has delayed a bit, especially across eastern counties. Chance of thunder remains, but given the timing widespread strong to severe storms are not expected. Heavy rain remains the primary concern.

KEY MESSAGES

1) Showers and thunderstorms become more widespread late Saturday through Sunday. Heavy rain is the primary concern with a few stronger storms possible Sunday afternoon and evening.

2) High pressure should provide some relief from precipitation for the start of next week before rain chances return midweek.

DISCUSSION

KEY MESSAGE 1... The nearly stationary boundary that has lingered across the Ohio Valley will finally begin to move on Saturday, lifting north as a warm front. This boundary couple with a midlevel shortwave will result in widespread showers pushing across the area beginning Saturday afternoon into the evening. There is a narrow corridor roughly from Findlay to Marion where some strong to severe storms may occur with strong winds the primary threat, but a tornado or two cannot be ruled out. This corridor is the most likely to see these as daytime instability increases concurrent with the synoptic forcing. As the storms slowly spread east, areas will gradually begin to lose that daytime instability keeping the severe potential to a minimum. By late tomorrow evening, the entire area should see some showers. To highlight the scattered severe potential, SPC has kept the corridor from Marion to Findlay in a Day 2 Slight with a Marginal extending further east to a line extending roughly from Sandusky to Canton.

The bigger concern with these widespread showers is the very heavy and efficient rainfall that is expected to be associated with them. Deepening warm cloud layers combined with PWAT values in excess of 2" falling on already saturate surfaces could result in localized flooding. At times, storm motion may also becoming parallel to mean flow, suggesting the potential for isolated training storms to develop which would only enhance the flood potential. To highlight this concern, WPC has put the entire area (except far NEOH and NWPA) in a Day 2 Slight Risk ERO.

KEY MESSAGE 2... After this shortwave and associated surface low move a cold front east on Sunday, high pressure is expected to build east over the area and allow for a brief reprieve from precipitation across the area for the start of next week. Chances of precipitation look to increase Wednesday into Thursday as a low pressure system moves into the region from the central US. Models have this midweek system developing into a more robust synoptic trough with more support aloft. Model timing and positioning of this low still diverge quite a bit, but this may be another period to keep an eye on for heavy rainfall and the potential for strong to severe weather.

AVIATION /18Z Friday THROUGH Wednesday/

Rain has largely ended across the area this afternoon, with a few scattered showers around Wooster and Canton. Showers and MVFR ceilings will diminish after 21Z for most terminals, with a high VFR ceiling and light/variable winds persisting into the evening. This will favor development of IFR fog across the southern portion of the region overnight, along and south of a line from FDY to YNG. Pockets of dense fog are likely in this area, especially around CAK/AKR. Conditions will improve to VFR after 15Z tomorrow, with winds becoming south-southeasterly at 5-10 knots.

Outlook...Non-VFR possible with showers and thunderstorms return Saturday night through Sunday evening. High pressure will build behind a cold front Monday afternoon and continue into Wednesday morning.

MARINE

As high pressure exits the Upper Great Lakes, low pressure and its associated frontal system will move eastward across the Upper Great Lakes. A warm front will cross Lake Erie Saturday night into Sunday morning, followed by a cold front Sunday evening into Sunday night. Offshore flow, meeting or exceeding 20 knots, is possible Saturday. Chances for winds >20 knots and waves >4 ft increase Sunday into Sunday night, as winds shift out of the west to northwest. A Small Craft Advisory and Beach Hazard Statement may be needed this forecast period.

CLE WATCHES/WARNINGS/ADVISORIES

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