textproduct: Cleveland

WHAT HAS CHANGED

There is a Slight Risk (Level 2 of 5) of severe weather for the entire area later today. There is a Marginal Risk (Level 1 of 5) of severe weather for the entire area on Saturday.

KEY MESSAGES

1) Dangerous heat and humidity will continue today followed by temperatures not as hot this weekend.

2) Daily chances for showers and thunderstorms will return later today with better opportunities for rainfall this weekend into next week.

DISCUSSION

KEY MESSAGE 1... We have one more day today of very hot and humid weather conditions before we start to see some relief. There are already signs that the "heat dome" which has been over the Ohio Valley and Mid-Atlantic region is beginning to break down and shift southward away from our area. There are some scattered convection just northwest of our area this morning which is one indication that the ridge of high pressure is weakening.

As for today, isolated to widely scattered convection over southern Lower Michigan may track across Lake Erie later this morning and skirt by our lakeshore. This weaker convection may leave out an out flow boundary for new showers and storms to develop later this afternoon and push further into northern Ohio and NWPA. High temperatures will climb back into the middle to upper 90s areawide. The heat index will once again be between 100 and 107 degrees this afternoon. The ongoing Extreme Heat Warning for northern Ohio and Heat Advisory for NWPA looks good at this time with no changes needed. Due to added cloud cover and higher POPs this weekend, high temperatures will not be as hot in the middle 80s to low 90s. More seasonable warm temperatures are expected to continue through much of next week with daily highs in the middle to upper 80s.

KEY MESSAGE 2... Our rain chances will gradually increase starting this afternoon and evening as the area becomes more influenced by the westerly flow over the top of the exiting ridge of high pressure. Afternoon and evening POPs will increase between 30 to 50 percent later today. Widely scattered convection will be possible across much of the area later today in the vicinity of residual outflows from overnight activity and local lake breeze enhancement. Deep layer shear and flow will support the potential for a few strong clusters of convection which may produce damaging wind gusts. SPC has the entire area in a slight risk later today for severe storms with damaging wind gusts as the main threat.

POPs will increase to likely for much of the area Saturday afternoon and evening. Now this does not mean a complete wash out for July 4th plans, but it does mean that there will likely be scattered showers and storms throughout the afternoon and evening. SPC has the area in a marginal risk day 2 outlook for a few strong to severe storms with damaging wind gusts on Saturday. The best chance of POPs and more widespread chances for showers and storms will be on Sunday. POPs will increase between 75 and 90 percent Sunday afternoon and evening. A couple stronger storms with damaging wind gusts may also be possible. The airmass will be very moist this weekend with PWATs of 1.5 to 2 inches. Any convection that is slow moving or training over the same area will be capable of producing locally heavy rainfall both Saturday and Sunday.

An upper level trough will continue to slowly track eastward across the Great Lakes region on Monday with an associated cold front. POPs will remain high Monday for scattered convection. Slightly drier weather will follow by the middle of next week before rain chances increase again towards the end of the week.

AVIATION /12Z Friday THROUGH Tuesday/

VFR is expected to prevail through the TAFs outside of convection. Upstream activity has dissipated this morning, leaving a clean slate to start the day. A few storms may try developing along a lake breeze boundary northeast of Cleveland early to mid-afternoon, potentially impacting ERI. Otherwise, scattered storms are favored to develop across far northern Ohio or Lake Erie along an old outflow boundary late this afternoon into this evening and move east-southeast into the area, before dissipating and/or exiting late evening into the overnight. Confidence in impacts to any given terminal remains on the lower side, as widespread thunderstorms are not expected and forcing is weak. The signal appears solid enough to go with a TEMPO at TOL, with continued VCSH and PROB30 groups at the other terminals. Expect more refinement as confidence in terminals potentially impacted vs not increases. We should then be dry and VFR for most of tonight, but will need to watch for additional clusters of showers/storms to arrive from the west- northwest late tonight into early Saturday. For now confidence is too low to include in any TAFs, but future cycles may need to add something after roughly 9z Saturday.

Winds will be out of the west-southwest and under 15kt through the period outside of any convection. Locally stronger wind gusts over 40kt may occur in/near thunderstorms.

Outlook...Occasional shower and storm potential continues this weekend ahead of a cold front. Weak low pressure moves overhead Sunday night into Monday, continuing occasional shower/thunder potential and possibly bringing non-VFR ceilings.

MARINE

Winds will remain generally southerly or southwesterly at under 15kt through Sunday, keeping waves in the 1 to 2 foot range. Lake breezes will flip winds a bit more onshore each afternoon, especially northeast of Cleveland, which may push choppiness into the nearshore waters. Occasional potential for thunderstorms exists this afternoon through the weekend. Briefly higher winds and waves will accompany any thunderstorms over the lake. Low pressure tracks over or just south of Lake Erie Sunday night into Monday, bringing winds around to a more easterly and then northerly direction at 15kt or less. This will push some choppiness into the nearshore waters, but expected to remain below headline criteria through the forecast.

CLIMATE

Dangerous heat and humidity is expected again today. Record warm high temperatures may be challenged. Here are those records for each of our climate stations:

Date Toledo Mansfield Cleveland Akron Youngstown Erie 07-03 100(1911) 93(2020) 98(1949) 97(1911) 98(1898) 93(1934) 07-04 100(2012) 96(2012) 98(1990) 99(1911) 99(1897) 99(1990)

CLE WATCHES/WARNINGS/ADVISORIES

OH...Extreme Heat Warning until 8 PM EDT this evening for OHZ003- 006>014-017>023-027>033-036>038-047-089. PA...Heat Advisory until 8 PM EDT this evening for PAZ001>003. MARINE...None.