textproduct: Cleveland

WHAT HAS CHANGED

Confidence in heavy rainfall and minor flooding Tuesday afternoon through Tuesday night has increased a bit across Northeast Ohio/Northwest Pennsylvania. Otherwise, the forecast and key messages largely remain the same.

KEY MESSAGES

1) Multiple rounds of showers and thunderstorms are expected tonight through Tuesday night with the highest confidence Tuesday evening into Tuesday night. Storms may be strong to severe and will produce heavy rainfall late Tuesday.

2) Periodic showers and thunderstorms and above normal temperatures will continue through the weekend as multiple systems cross the area.

DISCUSSION

KEY MESSAGE 1... The weather pattern will become unsettled tonight and especially Tuesday/Tuesday night as a cold front slowly progresses southeast towards the local area. Scattered showers and perhaps a few thunderstorms will become increasingly likely tonight with the highest chances across far NE OH and NW PA. The best (elevated) instability is expected to remain to the northwest of the area through early Tuesday so the potential for any stronger storms is quite low at this point. It will be quite warm and breezy on Tuesday with highs in the 70s and peak gusts of 30 to 40 mph likely during the afternoon. A few gusts to 45 mph are possible across portions of NW OH during peak diurnal mixing.

Multiple rounds of showers and thunderstorms are anticipated as the front nears the northwestern fringe of the CWA Tuesday afternoon and as the front moves southeast across the area Tuesday night. An initial round of showers/storms is possible near the lakeshore of NE OH and NW PA with a pre-frontal shortwave during the afternoon, although confidence in the coverage and intensity of storms is conditional and low at this point. Widespread cloud cover from overnight/early day convection may limit instability which would inhibit convection development during the afternoon. If sufficient destabilization occurs, there may be some stronger storms that are capable of producing gusty winds and hail. Confidence in precipitation is highest with the best forcing Tuesday evening into Tuesday night. With that being said, instability remains a bit questionable due to uncertainty in the timing of the front. By early evening, effective bulk shear values will increase to at 40 knots which will support organized showers and storms. If instability remains in place, all storm modes including damaging wind gusts, large hail, and a few tornadoes are possible. A Slight Risk for severe weather (level 2 of 5) is in place along and north of U.S. Route 30 with a Marginal Risk (level 1 of 5) south.

Heavy rainfall will accompany convection Tuesday night and there is concern for training storms and flooding given flow parallel to the frontal boundary and near-record precipitable water values (greater than one inch). The area of greatest concern is far NE OH into NW PA where at least 1.5 to at least 2 inches of rain could fall between late tonight and Tuesday night. Elsewhere, QPF values will generally be an inch or less, but locally higher amounts are possible where thunderstorms train.

KEY MESSAGE 2... Multiple rounds of rain and periodic chances of thunderstorms will continue through late week as the aforementioned cold front slows over the southern part of the area or the Ohio Valley Wednesday and lifts north as a warm front on Thursday. A series of systems will likely cross the area late week into the weekend, but it's still far too early to speculate on possible impacts. While there aren't any strong signals for flooding during the late week period, the continuous showers may keep local creeks/streams elevated.

Temperatures will cool slightly on Wednesday with warm air advection allowing temperatures to climb well into the 70s on Thursday. Locations in the southern half of the area may make a run for the lower 80s, especially if there's a lull in precipitation and a break in clouds. Highs in the 70s are expected to continue into the weekend with overnight lows remaining above normal.

AVIATION /00Z Tuesday THROUGH Saturday/

Prevailing VFR conditions this evening through the 18z Tuesday. Restriction likely due to lowered ceilings and possible TS for taf sites near the lake after 18z Tuesday. Included a tempo group for showers with visibility restriction down 4sm at ERI through 04z. Elsewhere, especially east of I-71, there is the potential for scattered showers and isolated thunder this evening, though confidence in coverage was too low for inclusion (CLE/CAK/YNG). Thunderstorm chances, particularly across the northern TAF sites (TOL/CLE/ERI), will increase after 18Z Tuesday. Ergo, we have added to -SHRA at all taf sites. and may need to be included in the next TAF package.

Winds will remain elevated overnight, 10 to 15 knots, with less gusts. A marginal LLWS threat will remain in the forecast overnight as a 2kft southwest LLJ of 45 to 50 knots develops and persists into Tuesday morning. Winds will increase again out of the southwest late Tuesday morning, 15 to 20 knots with periodic gusts of 30 to perhaps 35 knots by early afternoon.

Outlook...Non-VFR likely in showers and thunderstorms Tuesday night into Wednesday. Additional periods of non-VFR conditions possible in showers and thunderstorms Thursday through Saturday.

MARINE

Elevated southwest winds of 15 to 20 knots will persist across Lake Erie into Tuesday night. Though winds may occasionally gust up to 25 knots, believe most of the higher winds should be confined along the nearshore given the cold lake surface temperatures. Thus, have opted against a Small Craft Advisory at this time. The latest SAR imagery from this morning corroborates this, with mainly 10-knot winds found beyond 2 NM. Winds will briefly shift towards the north behind a cold front on Wednesday, 10 to 15 knots, increasing to 15 to 20 knots and gradually becoming east to northeast Wednesday night into Thursday. Winds will return to the southwest as the cold front lifts back north as a warm front late Thursday, 15 to 20 knots.

CLE WATCHES/WARNINGS/ADVISORIES

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