textproduct: Cleveland

WHAT HAS CHANGED

A Heat Advisory has been issued for all of northern Ohio through Saturday evening.

KEY MESSAGES

1) Heat and humidity will continue today followed by temperatures not as hot Sunday into next week.

2) Scattered chances for showers and thunderstorms expected this weekend through early next week.

DISCUSSION

KEY MESSAGE 1... The "heat dome" or upper level ridge of high pressure that has brought so much heat and humidity this past week is almost done impacting our weather across the region. We will still have some lingering heat and humidity to contend with today with highs in the upper 80s to lower 90s. Our heat index values will be around 100 degrees, especially across northern Ohio. We have extended heat headlines with a Heat Advisory for today into this evening for all of northern Ohio. High temperatures will be closer to seasonable warm levels for early July starting Sunday through early next week in the lower to middle 80s. High temperatures may creep back up into the middle to upper 80s later next week. Overnight low temperatures will be slightly more comfortable next week in the lower to middle 60s away from the immediate lakeshore.

KEY MESSAGE 2... The active storm track has shifted southward back into the lower Great Lakes and Upper Ohio Valley region thanks to the "heat dome" sliding away from our area. This means that we will see several days of unsettled and stormy weather this weekend into early next week. There is a weak mid level disturbance riding over the top of the ridge into northwest Ohio this morning with some scattered convection. The expectation is for this area of general convection to move eastward through the morning hours and weaken. It will leave out some outflow boundaries which new convection will develop around this afternoon and evening. Given the deep layer shear and some healthy downward CAPE values, there is a marginal risk for a few strong to severe storms with damaging wind gusts later today.

A weak mid level short wave trough will approach the area from the west Sunday and Monday. This trough will keep a higher chance for scattered showers and thunderstorms in the forecast through Monday. Given the very moist airmass in place with PWATs of 1.5 to 2 inches any thunderstorm that does develop will be capable of producing locally heavy rainfall. There is a Marginal Risk (Level 1 of 4) for Excessive rainfall both today and Sunday.

High pressure will build into the Ohio Valley and lower Great Lakes region Tuesday and Wednesday with lower rain chances. A broad upper level trough pattern may develop towards the end of next week over the Great Lakes region with a weak cold front moving through late Thursday. Some higher POPs will return back in the forecast by then.

AVIATION /06Z Saturday THROUGH Wednesday/

There may be some patchy non-VFR vsby in mist early this morning through 12 or 13z at a few sites, otherwise the main concern through the TAFs continues to be convection. A cluster of convection extends from southern MI across northern IN and into central IL as of 6z. This cluster is moving east-northeast at about 25kt. It is on a weakening trend, but may still bring TS to TOL/FDY early this morning and perhaps a shower to ERI later this morning. Given low confidence currently have PROB30 groups in for TSRA at TOL and FDY, though may need to AMD if the activity looks to hold together. Shifting to this afternoon and evening, the early morning cluster of storms is expected to leave an outflow boundary that will be a focus for renewed thunderstorm development this afternoon farther southeast. Have this activity included at CAK as a PROB30 and at YNG as a TEMPO. Will also need to watch MFD, but confidence is <30%. Additional storms will likely develop farther west or southwest and drift towards TOL, FDY, and MFD this evening. Confidence is low in impacts to specific terminals so handled with PROB30 groups to give an idea of timing, and will hone in more as we can through the day. It is currently more likely that convection remains south and west of CLE and ERI this afternoon and evening, so do not have an TSRA in those TAFs at this time.

Winds will start south-southwest today, but will shift more westerly through the afternoon and even gain a northerly component closer to Lake Erie. Nearly calm winds early this morning will increase to 6-12kt during the day. Some stronger thunderstorms can produce brief and sporadic wind gusts over 40kt this afternoon and evening.

Outlook...Weak low pressure and a cold front move across the region Sunday and Monday, bringing occasional showers and thunderstorms. Non-VFR ceilings and visibility also possible Sunday night into Monday.

MARINE

West-southwest winds of 5-10kt this morning shift a bit more west-northwest this afternoon and evening as a weak cold front crosses the lake. Winds gradually turn east-northeast tonight into Sunday, and increase to around 15kt Sunday afternoon and evening as weak low pressure approaches from the west. Winds then persist out of the northeast early this week as low pressure slowly tracks through the upper Ohio Valley. High pressure builds in towards midweek. The current forecast keeps winds in the 10-15kt range and waves in the 1-3 foot range Sunday night through Monday night. Some guidance suggests a period of winds to around 20kt is possible Sunday night into Monday as low pressure makes its closest pass. If these trends continue we will need to nudge the wind and wave forecast up, and may get close to needing Small Craft/Beach Hazards headlines between the Islands and Willowick for a period of time. Any thunderstorms over the lake over the next few days can bring briefly higher winds and waves.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Heat Advisory until 8 PM EDT this evening for OHZ003-006>014- 017>023-027>033-036>038-047-089. PA...None. MARINE...None.