textproduct: Cleveland

WHAT HAS CHANGED

Timing of rain has slowed by a couple hours this morning. Trended high temperatures down slightly today and warmer on Sunday.

KEY MESSAGES

1) Showers with scattered thunderstorms are expected today with a lesser chance on Sunday.

2) Temperatures warm through the weekend, peaking with summer-like conditions on Monday and Tuesday. A few locations may approach record values.

3) Potential for showers and thunderstorms return late Tuesday into Wednesday ahead of a strong cold front.

DISCUSSION

KEY MESSAGE #1: Shortwave energy will lift northeast across the area today with moisture advection focused around the ridge up the Mississippi and Ohio Valleys. Early this morning we are watching convection ongoing across Lake Michigan that will continue to track to the northeast. In addition, scattered showers are starting to spread northeast into the lower Ohio Valley where low level jet energy is focused. While the airmass overhead is dry this morning, significant theta-e advection up through 700mb is expected to spread east across the local area by early afternoon. Moistening of the column will result in an expansion of showers, although latest model trends from the 06Z HRRR suggest it may be a couple hours slower than previously thought. Up to 500 J/kg of MU CAPE does spread overhead this morning and could see a few elevated thunderstorms through early afternoon. After that, timing of showers and thunderstorms becomes a little more difficult and will be impacted by the first round and ability to recover. The general thought is for some modest instability to develop in NW Ohio and see scattered thunderstorms develop as stronger shortwave energy passes to the north. Development to the east is expected to continue through the afternoon as the area is caught in a broad area of convergence between energy moving around the ridge and the trough passing across the Upper Great Lakes. Most of the area(excluding NE Ohio and NW Pennsylvania) has been included in a Marginal Risk for severe thunderstorms this afternoon. While not the most impressive set-up, 0-6km shear of 25-30 knots could be sufficient for a low end wind threat with a few gusts of 50-60 mph possible later this afternoon.

The moisture axis will remain overhead on Sunday morning and then lift north as a warm front through the afternoon. Weak convergence along this axis could support additional scattered thunderstorms across mainly the northern half of the area on Sunday afternoon.

KEY MESSAGE #2: The flow aloft amplifies over the weekend with a ridge with 500mb height of 585 dm expanding north across Lake Erie. The warm front will be located well north of the area on Monday with 850mb temperatures of 16-18C overhead. While Sunday will be warm with temperatures in the mid 80s, Monday and Tuesday will be hot as highs reach the upper 80s and possibly 90 degrees. Temperatures through the first half of May have averaged 6-8 degrees below normal so this first blast of summer heat will feel quite warm. Temperatures will even approach record values at some locations on Monday and Tuesday (see the climate section below). Monday is expected to be dry and mostly sunny aside from a very low chance pop in NW Ohio. Clouds and chances for thunderstorms return on Tuesday.

KEY MESSAGE #3: Low pressure will track through the Upper Great Lakes on Tuesday. Most of the day will be dry but a prefrontal trough associated with this feature could kick off showers and thunderstorms on Tuesday afternoon. Timing will be impacted by energy lifting out of the Rocky Mountain trough across the Great Lakes region. Potential for showers and thunderstorms continues Tuesday night into Wednesday as the upper level ridge breaks down with an eventual cold frontal passage on Wednesday. Highs on Wednesday are already forecast to be 10-12 degrees cooler on Wednesday but they may need to trend down based on timing of the cold front.

AVIATION /06Z Saturday THROUGH Wednesday/

VFR early this morning. A warm front will lift east-northeast across the area this morning/early afternoon. There will likely be scattered to numerous showers with a few embedded storms with the warm front. While the potential for thunder with this first round is somewhat ambiguous due to marginal instability, confidence in at least some showers is fairly high within a few hour window at all terminals and is reflected in the TAFs. Confidence in what happens between mid-afternoon and evening behind the warm front is lower. A disturbance aloft may be enough to spark a second round of showers and storms, but confidence in enough warmth and instability building that quickly behind the initial round of precipitation is lower. Potential for afternoon showers/storms is higher farther south and lower to the north. Mainly handled the afternoon activity with PROB30 groups due to lower confidence. Confidence in drier weather returning increases into tonight. Some MVFR ceilings will likely be around at times this afternoon into tonight as low-level moisture increases.

Mainly light south winds in the 5-10kt range early this morning will shift more southwest today, increasing to 10-18kt with gusts 20-25kt during the midday and afternoon hours. Winds become lighter and lose their gusts this evening and tonight.

Outlook...Non-VFR possible in showers and thunderstorms Sunday afternoon and evening, though chances are lower. Non-VFR likely at times in showers/thunderstorms late Tuesday into Wednesday.

MARINE

South to southwest winds in the 10-20kt range are expected over the lake today. Winds may be a bit gusty at times in the nearshore late this morning and this afternoon...current impression is any gustier winds will be too short-lived for a Small Craft Advisory, though trends will be monitored. Either way, waves up to 2 feet in the nearshore waters and 2 to 4 feet in the open waters through early this evening. Winds and waves diminish tonight into early Sunday, with winds turning more easterly at under 15kt on Sunday. Winds turn back to a more south to southwest direction Monday and Tuesday. Winds will generally be 10-20kt early this week over the lake, but will need to watch for winds to briefly reach 20kt sustained with higher gusts Monday and Tuesday afternoons, particularly in the western nearshore waters. Waves will generally be 2 to 4 feet in the open waters and up to 2 feet in the nearshore early in the week. Can not rule out some eventual consideration for a Small Craft Advisory Monday or Tuesday afternoons in the stronger south-southwest winds, especially west of Cleveland. Thunderstorm potential increases Tuesday and Tuesday night.

CLIMATE

High temperatures on Monday and Tuesday will approach record values. The following are the records for May 18 and 19 at local climate sites.

Date Toledo Mansfield Cleveland Akron Youngstown Erie 05-18 95(1962) 92(1962) 91(1962) 92(1962) 92(1962) 89(1889) 05-19 92(1996) 88(1964) 88(1998) 91(1911) 89(1934) 90(1996)

CLE WATCHES/WARNINGS/ADVISORIES

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