textproduct: Cleveland

WHAT HAS CHANGED

A Heat Advisory has been issued for Central and Northwestern Ohio for this afternoon.

KEY MESSAGES

1) Heat and humidity continues for one more day across Central and Northwestern Ohio with heat indices in the upper 90s to low 100s.

2) Rounds of showers and thunderstorms continue today through early Saturday morning with the potential of storms being severe today and Friday.

3) Quiet weather and seasonable temperatures are expected this weekend into early next week.

DISCUSSION

KEY MESSAGE 1... Elevated heat risk will continue for one more day across Central and Northwestern Ohio today before temperatures begin to moderate Friday into the weekend. The ridge is slowly beginning to retreat to the southwest as low pressure moves north of the Great Lakes to the east. 850mb temperatures will still be around 20-22C for the western half of the CWA resulting in surface temperatures to be in the low 90s. Dew points again will be elevated in the low to mid 70s that will push heat indices to around 100F this afternoon into the early evening. There's some uncertainty with the eastern extent of the elevated heat indices as precipitation is expected over the course of the day today. Current guidance suggests that precipitation will be scattered in Eastern Ohio through the morning and into the afternoon that will help keep heat indices down overall to the east. Whereas Western Ohio should be free of any scattered precipitation so temperatures will have the chance to climb before precipitation is expected in the early evening. By that time, more widespread precipitation is expected to move in from the northwest that will temper heat indices this evening. Based on this, a Heat Advisory has been issued for Central and Western Ohio for this afternoon into the evening. Overnight, temperatures will still be warm with lows in the upper 60s to low 70s, though will not rise as much on Friday due to the rounds of precipitation expected throughout the day. A cold front will move south across the region late Friday into early Saturday and temperatures will regulate back to around seasonal for the weekend and into early next week.

KEY MESSAGE 2... More rounds of thunderstorms and potential severe weather will continue through today and Friday and, to a lesser extent, Saturday morning. There will be isolated morning convection across the eastern portion of the CWA that should exit to the east with the shortwave. Another shortwave is expected to move into the region this afternoon/evening bringing support for more thunderstorms and severe weather potential. Instability will still be elevated with MLCAPE around 1500-2000 J/kg and bulk shear of 30-35 knots. Lapse rates will also climb to around 7.0-7.5 C/km with daytime heating. This will promote downburst potential across the region during the afternoon and evening for any storms that start to develop. The better chance for showers and thunderstorms will be in the later evening into the overnight with the shortwave. Clusters of thunderstorms are possible with this that will bring the threat for damaging wind gusts and large hail. An isolated tornado is possible as well as 0-1km shear vectors increase ahead of the feature. SPC has highlighted the entire area today in a Slight Risk (Level 2 out of 5) for severe weather due to this. The shortwave should exit to the southeast early Friday morning and a brief break is expected ahead of the next shortwave.

This shortwave will enter the region from the northwest mid-morning Friday moving to the southeast. The ridge will have retreat to the southwest more by this time so the thunderstorm chances will have moved along with it to be more focused on the central and western portions of the CWA. There won't be much recover in the atmosphere between the previous shortwave and this one, so the severe weather threat will be lower. That being said, there will still be plenty of instability, especially in Central and Northwestern Ohio that will help support any severe weather. There's still some discrepancies among the models for Friday in regards to timing and coverage, but generally, coverage should be lower, limiting the overall severe weather impacts. A cold front will be associated with this shortwave as it pushes to the south through early Saturday. The front will be slow to move out of the area, so lingering showers and thunderstorms are possible into early Saturday morning.

In addition to the severe weather potential, there will be the chance for heavy rain and flooding in places that see persistent rainfall. With the elevated CAPE, PWATs will be around 1.50-2.00" across the region that will give enough support for the flooding potential. Generally, the time frame that looks to be the most susceptible to flooding will be tonight into Friday.

KEY MESSAGE 3... High pressure will begin to build across the region Saturday afternoon and persist through early next week. Building south from Canada, this will drop high temperatures to a more pleasant upper 70s to low 80s with lower humidity. Overnight lows will be down into the upper 50s to low 60s as well.

AVIATION /12Z Thursday THROUGH Monday/

Morning convection will linger until about 14Z and then a period of no activity through around 21Z today. Cumulus field develops at that point and then utilize TEMPO groups for the next round of showers/storms. Timing will be roughly 21Z Thursday through 01Z Friday, with storms characteristic primarily of gusts, which is also included in the TEMPO. Low confidence after the storms today but the chances for another round overnight are non-zero, but will not mention in the TAF for now. Late tonight in the eastern terminals, low end MVFR ceilings move in to the area.

Outlook... Non-VFR possible in rounds of showers/storms through early Friday.

MARINE

A stationary front will oscillate north and south along Lake Erie through Friday before finally pushing southward and through the region. Variable winds can be expected through this period with wave heights around a foot during this time frame. Once the cold front passes south of the lake, winds will increase out of the northeast 10-20kts into the weekend with central and western wave heights building to 2-3ft through Sunday. Winds offshore once again after Monday with wave heights back down to a foot or less.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Heat Advisory from 2 PM this afternoon to 8 PM EDT this evening for OHZ003-006>008-017>019-027>031-036>038-047. PA...None. MARINE...None.