textproduct: Cleveland

WHAT HAS CHANGED

Lowered relative humidity for this afternoon and low temperatures for tonight. Tried to indicate two rounds of precipitation during the Friday night/Saturday time frame with the first being after midnight Friday night, then showers and thunderstorms expanding again during the afternoon on Saturday.

KEY MESSAGES

1.) Friday will trend warmer with highs in the mid to upper 80s.

2.) Rain chances return Friday night then again Saturday afternoon with the potential for scattered severe thunderstorms and locally heavy rain. The primary concern will be damaging wind gusts.

3.) Above normal temperatures return for the middle of next week.

DISCUSSION

KEY MESSAGE 1... A high amplitude ridge extends north to the Great Lakes Region. This ridge will gradually build east through Friday with southwesterly flow increasing. Above normal temperatures will expand eastward across the area with high temperatures in the mid to upper 80s. A lake breeze still looks possible along the northeast lakeshore and towards Erie so temperatures will max out a few degrees lower in that area. Otherwise dewpoints will gradually start to trend upwards into the mid and upper 50s. KEY MESSAGE 2... As the ridge axis shifts to the east on Friday, active weather returns with multiple shortwaves and a trough pushing a cold front south out of Canada. The first good push of moisture in the 850-700mb layer arrives Friday evening as a shortwave moves out of the Plains and helps to flatten the ridge aloft. A low level jet will provide the lift for showers to expand east across Lake Erie Friday night with a few thunderstorms possible. This more focused lift shifts east of the area by Saturday morning leaving cloudy skies and decreasing coverage of showers. However the potential remains for at least a few showers to continue as a deep moisture axis with PW values of 1.75" will be located overhead.

The question on Saturday will be how well we recover with some breaks in the clouds and a cold front settling south Saturday afternoon and evening. It looks as if the more favorable axis for airmass recovery could arrive from the west with 1200-1500 J/kg of CAPE returning. The NAM shows an area of 2500+ CAPE but this seems to be due to the simulated dewpoints of 70 degrees in the model which are likely too high. It seems the potential for greatest coverage of storms will be where the instability interacts with the approaching front which may be across the southern half of the forecast area. Some training of storms may even occur with nearly unidirectional flow aloft but have at least 50-60 pops everywhere for Saturday afternoon and evening. A 50 knot jet at 500mb ahead of the upper trough swinging through the eastern Great Lakes will create a concern for scattered strong to severe storms and the Storm Prediction Center has the area included in a Slight Risk of severe thunderstorms for Saturday, generally between 2-8 PM. Damaging winds will be the primary concern along with locally heavy rain and some potential for training.

KEY MESSAGE 3... Temperatures behind this trough will trend cooler for Sunday before a warming trend returns for next week. The trend will be for ridge to build aloft again although with the potential for it to be delayed by a trough lifting out of the Plains. It looks like we will be dealing with more summer-like heat for the middle of next week with temperatures approaching 90 degrees or higher for portions of the area.

AVIATION /06Z Friday THROUGH Tuesday/

VFR is expected to persist through the bulk of the TAF period. A weakening cluster of convection will push east towards terminals late Friday night into early Saturday morning, though anticipate much of the convection to remain near the lakeshore. For now, have included PROB30 lines for KTOL and KCLE to time out any TSRA impacts roughly between 04Z/Sat and 12Z/Sat.

Light southwesterly winds 5-8 knots tonight will increase to 12-15 knots by Friday afternoon with gusts of 20-25 knots possible. A lake breeze will likely shift winds west-northwest at KERI Friday afternoon.

Outlook...Limited non-VFR in a cluster of weakening showers and thunderstorms Friday night into early Saturday. Non-VFR possible again Saturday afternoon and evening as thunderstorms develop along and ahead of a cold front.

MARINE

Southwesterly winds generally remain between 5-15 knots through this evening before increasing to the 15-20 tonight range tonight through Saturday morning. A cold front will move across the lake on Saturday evening allowing for winds to turn northerly while decreasing to 10 knots or less by Sunday morning as high pressure builds overhead. Light and variable flow is expected as the high remains in control on Sunday. Winds will favor an easterly component Monday while remaining in the 5-15 knots range ahead of an approaching low pressure system that will enter the Upper Ohio Valley by mid-week.

CLE WATCHES/WARNINGS/ADVISORIES

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