textproduct: Cleveland

WHAT HAS CHANGED

Current forecast remains on track compared to previous forecast cycle.

KEY MESSAGES

1) Shower and thunderstorm chances increase across the area late Saturday through Sunday. Heavy rainfall possible at times with strong to severe storms Sunday afternoon.

2) Unsettled weather pattern for the first half of next week, with periodic shower and thunderstorm chances.

DISCUSSION

KEY MESSAGE 1...

Aside from a few stray showers that could develop across portions of north central and northeast Ohio later this afternoon into early evening, dry conditions expected until shower chances increase through the day on Saturday. A positively tilted upper trough/closed low and attendant surface low pressure will slowly move east from the mid Mississippi valley into the Ohio valley Saturday through Sunday.

Shower and storm chances increase late tonight into early Saturday morning from west to east. The best chances for precip during the daytime will generally be west of the I-71 corridor, particularity in the far southwest portion of the forecast area from Findlay to Marion. Precip chances will increase across the rest of the area Saturday night as the low level jet ramps up and convergence increases across the area. Heavy rainfall will be possible with any convection, as PWAT values increase to 1.75-2.00 inches across the area. Hi-res guidance seems to focus the heaviest precip west of the area on the northwest flank of the surface low, but this precip maxima could sneak into the I-75 corridor by early Sunday morning depending on the evolution of the system. WPC is highlighting the far western part of the area in a slight risk of excessive rainfall Saturday and Saturday night.

As the upper trough amplifies over the region Sunday, mid/upper flow will increase a bit on the downstream side of the trough. Shower and storm activity will impact the forecast area as the surface low slowly pivots eastward. WPC continues to highlight a slight risk of excessive rainfall for much of the forecast area on Sunday with the combination of slow moving/training storms and intense rainfall rates leading to an increase in flash flood potential. SPC is highlighting areas east of the I-77 corridor with a marginal risk of severe weather. Deep layer effective shear of 30-35 kts during the afternoon, combined with MLCAPE values of 1000-1500 j/kg, could lead to some strong to severe thunderstorms as the convection tracks east out of the area into the evening. Damaging winds would be possible, and a tornado or two cannot be ruled out with low LCLs and somewhat favorable hodographs.

KEY MESSAGE 2... Confidence increasing in unsettled weather across the area Monday through Wednesday, as aforementioned mid/upper trough cuts off over the Ohio valley Monday. This will bring diurnally driven shower/storm chances through Wednesday before the low fills and lifts northeast into New England ahead of a northern stream shortwave moving into the northern Great Lakes region. This will also keep conditions humid and temperatures near seasonal normals. Areas that see heavy rainfall over the weekend could be vulnerable to an increased risk of flash flooding with any slow moving or training storms during this period.

AVIATION /00Z Saturday THROUGH Wednesday/

A few showers persist across portions of interior Ohio this evening, but are not affecting any TAF sites or producing any lightning. These showers should dissipate through 10PM/2Z. It is VFR outside of any showers this evening.

The focus then shifts to the west, as approaching low pressure gradually brings lower ceilings and shower/thunder potential from the west on Saturday. A few light showers may make it into Northwest OH pre-dawn Saturday. Included VCSH at TOL/FDY where confidence is somewhat higher. Restrictions are unlikely. These showers may make it as far east as MFD/CAK early Saturday, but confidence is too low for any inclusion. Greater potential for showers arrives from the west-southwest Saturday afternoon and evening. Initial activity looks hit or miss with limited lightning potential, so for now brought in the showers but kept prevailing conditions VFR through the end of the TAF periods. Kept any showers out of ERI and YNG through 0z. Potential for lower ceilings, locally heavier rain with vsby restrictions, and isolated lightning increases from the southwest Saturday night, beyond the end of the TAFs.

Winds will generally shift to the southeast tonight and Saturday. Winds will be light at generally <5kt tonight, increasingly modestly to 5-12kt Saturday afternoon.

Outlook...Occasional non-VFR in showers and thunderstorms Saturday night through Sunday night. Scattered showers and thunderstorms with potential for non-VFR continue Monday through Wednesday, primarily during the afternoon hours.

MARINE

Low pressure approaches from the west, potentially moving eastward south of or across Lake Erie Sunday into Monday. There is good deal of uncertainty with this forecast update regarding the low pressure system track, which greatly influences the wind and waves forecast for Saturday night through Monday. There is moderate confidence that there will be a period of east to northeast flow sometime Saturday night through Sunday, followed by higher confidence in northeast to north flow on Monday. It's becomingly increasingly likely that there will be a period of 15-20 knot onshore flow with waves in the 3 to 5 ft range, especially east the Island towards the Cleveland area, but there is a lot of uncertainty in exact timing. We will have to continue to monitor for possibly dangerous conditions for swimmers and small craft, especially in the central basin of Lake Erie.

Conditions on Lake Erie are likely to improve by midweek.

CLE WATCHES/WARNINGS/ADVISORIES

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