textproduct: Cleveland

WHAT HAS CHANGED

No significant changes with the morning update.

KEY MESSAGES

1) Dry with pleasant, below normal temperatures through Wednesday.

2) Showers and thunderstorms return Wednesday night and Thursday, with a few strong storms possible Thursday afternoon and evening containing gusty winds and heavy downpours.

3) Intermittent potential for rain Friday into early next week, with a gradual warming trend beginning on Sunday.

DISCUSSION

KEY MESSAGE 1... A large area of surface high pressure (Canadian high) will build down across the Great Lakes today and become centered over the Ohio Valley region by Wednesday. This will support mostly sunny skies with just pockets of cirrus at times and fair weather afternoon cumulus. The sunshine will allow for moderating temperatures compared to yesterday, but still a solid 5 degrees below normal for late June with highs in the low to mid 70s today and mid to upper 70s Wednesday. The high overhead will set up another chilly night tonight with lows in the low 50s, and small temp/dew point depressions may lead to quite a bit of fog, especially over interior portions of NE Ohio and NW PA. This will be monitored.

KEY MESSAGE 2... Wednesday night and Thursday will be the beginning of a more active pattern that will continue on into early next week. Broad mid/upper troughing that has been entrenched across the northern tier of the CONUS will continue to hold as a low amplitude shortwave trough progresses through the mean longwave trough. As this shortwave crosses the Great Lakes Thursday, a weak associated surface low will track eastward across the southern Great Lakes. This will lift a warm front across the region Wednesday night followed quickly by a cold front Thursday afternoon and evening as the low departs into the eastern Great Lakes. An initial round of showers and a few embedded rumbles of thunder should occur Wednesday night and early Thursday morning driven by weak warm air advection and isentropic ascent ahead of the warm front. Not confident that these showers will be widespread or amount to much, but a modest 65 knot upper jet will be enough for a 20 knot low-level jet response, and this will advect a little elevated instability into the area from the southwest. This could help some areas to see better rainfall coverage and amounts despite the unimpressive forcing.

Thursday afternoon and evening could be more interesting as the cold front crosses the region. There is still some disagreement in model guidance on the timing of the frontal passage, but if morning clouds and showers clear out in time and if the front holds off until late afternoon/evening, then there should be modest heating and resultant instability in the warm sector to trigger a broken line of convection. A rather impressive 90-95 knot H3 jet streak crossing the southern Great Lakes in the afternoon will generate plenty of lift and deep layer effective shear for organized updrafts if enough instability can be realized. Based on current consensus of frontal passage timing, the best chance for a few strong to severe storms will be along and east of I-71 Thursday afternoon into the evening. Any storms could produce gusty winds and brief heavy rain. The SWODY3 only shows general thunder at this point (no severe risk), but this will be monitored. Temperatures will warm to near 80 Thursday, and it will feel noticeably more humid as dew points creep into the 60s, especially after the cool weather of the past 10 days.

KEY MESSAGE 3... After the cold front progresses through the area Thursday, the boundary is likely to become quasi-stationary near the Ohio Valley region through the weekend before starting to lift back north early next week. The mid/upper pattern will feature the stubborn longwave trough that has dominated the northern tier of the CONUS lately slowly retreating into New England this weekend and early next week as a broad ridge amplifies over the central CONUS in response to a longwave trough amplifying west of the Rockies. Northern Ohio, NW PA, and the southern Great Lakes region will be wedged between the cooler influence of the lingering trough to the east and the heat dome building just to the west. This combined with a cool Canadian surface high over the eastern Great Lakes this weekend through early next week will keep the frontal boundary NW to SE oriented across the Ohio Valley. Multiple weak shortwaves progressing through the NW flow and interacting with the boundary will bring periodic chances for showers and thunderstorms Friday through the weekend, especially along and south of U.S. 30 in closer proximity to the boundary. At this point, the drier air from the Canadian high to the NE will probably win out for most of the area, so do not expect any heavy rain Friday through the weekend (most areas will stay dry outside of U.S. 30 and points south), but had to keep chance POPS. By Sunday and Monday, the mid/upper ridge to the west should expand into the area, and this should lift the boundary northeastward and allow the higher heat and humidity to build in. So, after a long stretch of cool and mostly pleasant weather, the heat and humidity will make a comeback for the end of the month.

AVIATION /12Z Tuesday THROUGH Saturday/

IFR stratus across Northeast Ohio and Northwest Pennsylvania will erode quickly this morning with a trend towards mostly sunny skies. North winds will be 10 knots or less with a few gusts to 20 knots in Northeast Ohio. Winds will become light and variable tonight as high pressure builds overhead. There will be potential for patchy fog tonight as ground moisture remains high with nearly calm winds. Chances for fog are highest in Northeast Ohio or at TOL where flow briefly turns off the lake and contributes additional moisture beneath the inversion.

Outlook...Non-VFR visibility expected on Tuesday night with fog. Non-VFR possible in showers and thunderstorms Wednesday night into Thursday, and again on Friday night into Saturday.

MARINE

North winds of 10-15 knots with waves of 1 to 3 feet on the central basin of Lake Erie this morning will decrease today as high pressure builds south into the region. Generally good marine conditions with winds of 15 knots or less will continue through Wednesday. Southwest winds increase to 10-20 knots on Thursday ahead of a cold front. Thunderstorms will be possible near or over Lake Erie on Thursday which may result in erratic wind and wave conditions. Onshore flow of 5-15 knots is likely heading into the weekend with high pressure to the north and the frontal boundary stalled somewhere over the Ohio Valley.

CLE WATCHES/WARNINGS/ADVISORIES

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