textproduct: Cleveland

WHAT HAS CHANGED

Forecast remains largely unchanged. There will be severe weather potential across the area this afternoon/evening with all hazards possible. Additional rounds of severe weather possible Thursday and Saturday.

KEY MESSAGES

1) Severe weather potential across the region continues this afternoon/evening with additional rounds possible Thursday and Saturday.

2) Multiple rounds of precipitation through Thursday night will bring flooding potential to the region. A Flood Watch remains in effect for northwestern Ohio.

3) Temperatures remain above average through Saturday evening with cooler temperatures for Sunday and Monday. Highest potential for frost/freeze will be Sunday night into Monday.

DISCUSSION

KEY MESSAGE 1... Severe weather potential continues this afternoon into the evening with additional rounds possible Thursday and Saturday as a boundary wavers through the central Great Lakes through the early weekend. See below for a breakdown for each day:

Today: Northern Ohio and northwestern Pennsylvania continues to destabilize this afternoon as ample moisture advects in from the southwest. As this occurs, MLCAPE values will rise to 1000-1500 J/kg this afternoon with low and mid-level lapse rates between 6.0-7.0 C/km. Lapse rates of those values could inhibit some thunderstorm potential. Additionally, given the southwestern surface flow, there will be decent low level and deep layer shear, especially across northern Ohio into Pennsylvania, that will support organized convection with all hazards possible to include damaging winds, hail, and possibly a tornado or two. Thunderstorms are currently getting started across eastern Indiana and western Ohio early afternoon along a boundary across that area. As this moves eastward more into Ohio, should expect to see a increase in coverage and intensity. Timing wise, the thunderstorms should enter in the western portion of the CWA by 2-3PM and traverse across exiting into Pennsylvania by 8-9PM. Another round of thunderstorms are possible late tonight after midnight with support from a shortwave moving through the region. Though, severe potential associated with those should be limited given the much lower instability and lapse rates.

Thursday: Another round of severe weather is possible on Thursday as an upper level low moves through the Great Lakes during the afternoon. Showers and thunderstorms will be in the area for the majority of the day with scattered severe potential given the continued southwesterly flow. The main threat will be in the evening with damaging wind potential as a cold front sweeps through the region. Can't rule out the possibility of a brief tornado or two along and ahead of the line, though shear values will be better during the morning to early afternoon out ahead of the best instability. The severe weather potential should begin to diminish around sunset and move out to the east.

Saturday: The next round of severe potential will be during the afternoon on Saturday as a low pressure system moves across the Great Lakes. A warm front will lift northward through the region Saturday morning with a cold front later in the evening. All modes of severe weather are possible, though the main threat will be damaging winds along the cold front as it moves through given the strong low to mid level winds.

KEY MESSAGE 2... With plenty of moisture advection across the region through Thursday night, there will be potential for moderate to heavy rainfall with the potential for flooding. Precipitable water values will be around 1.0-2.0 inches that will support rainfall rates of 1-2 inches per hour in thunderstorms. With the potential for showers and thunderstorms to continue from late this evening through Thursday night, flow will become more parallel to the boundary situated north of the area and support the potential for training storms. Generally expecting this to stay north of US Route 30. Through Thursday night, rainfall totals will be around 1-2 inches with the higher end amounts closer to the lake shore. Higher amounts will be possible in thunderstorms as well. Latest guidance has trended northeastern Ohio and northwestern Pennsylvania to receive more rainfall, though this will be dependent on where thunderstorms set up over the region so confidence is lower in this.

KEY MESSAGE 3... Temperatures through Saturday evening will continue to be above average. Highs will be in the mid to upper 70s as we continue to see southwesterly flow across the region. Low pressure will move through the Great Lakes on Saturday sweeping a cold front through that will usher in a much cooler air mass. Temperatures will drop down to 5-10 degrees below average with highs in the upper 40s to mid 50s. Overnight lows for Sunday night into Monday will be the coldest of this stretch, dropping down into the lower 30s with some locations possibly seeing upper 20s. Given the growing season as begun across Ohio, frost/freeze headlines will likely be needed Sunday night with a lower potential for Monday night. Temperatures will begin to moderate on Tuesday rising to around seasonally average.

AVIATION /18Z Wednesday THROUGH Monday/

Aloft, SW'erly to W'erly flow and embedded disturbances affect our region as a stronger disturbance moves E'ward and nears Lake Michigan and vicinity by 18Z/Thurs. At the surface, our region remains along the northwestern flank of a high pressure ridge. Our regional surface winds should trend S'erly to SW'erly around 10 to 15 knots through the TAF period. These winds should gust up to 20 to 25 knots at times, especially before 23Z/Wed and after 14Z/Thurs. Scattered to widespread low clouds are expected through the TAF period and any resulting ceilings should be in the 2kft to 6kft AGL range.

As of 17:30Z/Wed, lines and clusters of showers and thunderstorms had developed just west of our region in northern IN and far-NW OH. These showers/storms are expected to persist generally E'ward through our region through ~02Z/Thurs and produce the following: brief MVFR to IFR; brief and erratic surface wind gusts up to 40 to 55 knots. Some storms may also produce damaging hail. Behind these initial showers/storms, additional isolated showers and storms with brief MVFR to LIFR are possible the rest of this evening into Tuesday morning amidst low-level moist isentropic ascent aloft, but confidence remains very low that this additional convection will occur. After ~14Z/Thurs, additional scattered showers and thunderstorms may outpace the aforementioned stronger disturbance aloft and impact locations as far east as roughly the latitude of KCLE by 18Z/Thurs. These storms should produce brief/erratic surface wind gusts up to 40 knots and brief MVFR to LIFR.

Outlook...Periodic showers and thunderstorms with non-VFR are expected Thursday afternoon through Thursday night and again on Saturday. Additional periods of rain with non-VFR are expected Saturday night through Sunday evening. This rain may mix with or change to wet snow at times Sunday morning and again Sunday evening.

MARINE

A broken line of thunderstorms will cross Lake Erie early this morning and could be strong to severe. Thunderstorms will act to disrupt winds which could shift around to the northwest for a period of time. Winds will switch back around to the southwest on Wednesday at 10-20 knots with additional strong thunderstorms possible. Low pressure will track east across the Central Great Lakes on Thursday, with southwest winds veering to the northwest behind a cold front Thursday night.

Southwest winds develop out of the southeast on Saturday and veer to southwesterly at 15-20 knots. Winds will be elevated at 20-25 knots behind the cold front Saturday night and a Small Craft Advisory will likely be needed heading into Sunday.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Flood Watch through Thursday morning for OHZ003-006>009-018- 019. PA...None. MARINE...None.