textproduct: Cleveland

WHAT HAS CHANGED

Decreased QPF through Wednesday morning as coverage of showers and thunderstorms this afternoon and evening will be fairly isolated to scattered.

KEY MESSAGES

1) Daily chances for showers and thunderstorms continue into the weekend. Highest chances for precipitation will be this afternoon and evening and Thursday afternoon and evening.

2) Summertime heat and humidity enter the region with peak heat index values approaching 100 degrees by mid-week. Slightly cooler behind a cold front Friday into the weekend.

DISCUSSION

KEY MESSAGE 1... A shortwave aloft coupled with a surface warm front will lift east across the Upper Ohio Valley today. Showers and thunderstorms are expected to move through the region through the day today. Coverage of showers/storms will remain isolated to scattered with PoPs generally in the 40-60% range through tonight. Near record high PWAT values in a moisture rich airmass will provide a favorable environment for any shower/storm that develops to be capable of producing heavy rainfall. Given remaining uncertainty with timing and coverage of showers/storms, any flooding potential will be very localized or confined to areas where training showers/storms occur.

Any storms that occur this afternoon and evening should remain below severe limits, but can't rule out an isolated stronger thunderstorm given moderate instability (800-1200 J/kg SBCAPE) and deep-layer shear of 20-25 knots. As for Wednesday, isolated showers and thunderstorms may develop during the afternoon and evening hours given the moist and unstable airmass. The 00Z HREF shows increased instability (2000-2500 J/kg SBCAPE) and deep-layer shear increasing to 25-30 knots. A few severe storms may be possible with primary hazards of damaging wind gusts and large hail. SPC has highlighted our CWA in a Marginal Risk (Level 1 of 5) for severe weather on Wednesday.

A cold front will push towards the region during the day on Thursday with another period of afternoon showers and thunderstorms expected to develop ahead of the front. SPC has included the entire forecast in a Marginal Risk (Level 1 of 5) for severe weather on Thursday.

KEY MESSAGE 2... Anticipate a period of above normal temperatures with hot and humid conditions through the end of the week. Summertime temperatures with afternoon highs in the upper 80s to lower 90s will be coupled with dew points in the upper 60s to lower 70s. Heat indices will also be on the rise through the week with peak heat index values approaching 100F Wednesday and Thursday. Limited overnight relief as overnight lows will settle in the upper 60s to lower 70s. Early season heat is oftentimes more dangerous and can pose a greater risk for heat- related illness. Stay hydrated and take frequent breaks out of the sun and in cooled locations! Temperatures will fall behind cold front on Friday with cooler highs in the mid 80s expected through the weekend.

AVIATION /06Z Tuesday THROUGH Saturday/

The aviation forecast continues to be tricky, largely because of the fact that the upper level trough and warm front coming through the region during the period will be producing off and on and isolated to scattered convection through much of the period. This creates an issue where it is not nearly enough for prevailing or even TEMPO groups, so the use of PROB30 becomes the best play. However, it could be used in a large portion of the TAF period for most of the terminals, so the attempt here is to isolate the best chance of a terminal experiencing any sort of convective activity. That said, towering cumulus should be expected for most of the period, as should lowering ceilings to largely MVFR, and possibly IFR overnight. Winds become gusty 15-25kts out of the southwest during the daytime heating hours. AMDs should be expected.

Outlook...Periods of non-VFR likely in occasional showers and thunderstorms through Friday.

MARINE

Offshore winds today increase to 15kts with wave heights increasing to 1-2ft away from shore in the nearshore zones. Beginning tonight, these winds will become southwesterly 10-15kts through Friday. Wave heights in the western and central basins, where southwesterly winds are more offshore in nature, will be less than a foot adjacent to the shore and will increase to 1-2ft away from shore in the nearshore zones. Cleveland eastward, wave heights will be 1-2ft for the entire nearshore zone with winds parallel to the shoreline.

CLE WATCHES/WARNINGS/ADVISORIES

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