Area Forecast Discussion
Issued by NWS Cleveland, OH
Issued by NWS Cleveland, OH
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973 FXUS61 KCLE 211745 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 145 PM EDT Fri Jun 21 2024 .SYNOPSIS... An upper level ridge will continue to slide southwest, away from the area, today into Saturday. Low pressure will develop over the Upper Midwest on Saturday and slide across the Great Lakes on Sunday, extending a cold front across the area. High pressure will build across the region for Monday. && .NEAR TERM /THROUGH SATURDAY/... 9:50 AM Update... Forecast remains mostly on track. Made some minor changes to PoPs through this evening to account for recent hi-res guidance. Scattered showers and thunderstorms will develop along a surface boundary this afternoon and into the evening. Best chance for thunderstorms will once again occur across Northwest Ohio where our warm and unstable airmass with a primary hazard of damaging wind gusts. 7:00 AM Update... Low stratus and fog hover around Northwest Ohio this morning, where better moisture remains after showers and storms on Thursday evening. This area will become better suited for shower and storm development by late morning/early afternoon and have bumped up the timing for scattered showers and storms in the Toledo area. Otherwise, the forecast remains on track at this time. Previous Discussion... The near term forecast forecast continues to sound like a broken record. An upper ridge across the region will continue to support above normal temperatures with high dew points in the upper 60s to lower 70s through Saturday. This air mass will continue to allow for heat stress on people and infrastructure with heat index values near 100 and the environment remains supportive for isolated to scattered showers and storms. For today, temperatures will be slightly tapered from the past 4 days with a subtle boundary laced across the southern Lake Erie shoreline. With a slightly modified lake breeze during the afternoon hours, this could push slightly inland and keep temperatures a few degrees lower and offer some very light refreshment from the days of heat. Meanwhile, with some mixing across the region, dew points across the area have fallen off just a bit with some low to mid 60s into NE OH and NW PA, allowing for heat index values likely staying in the low to mid 90s. However, with the boundary sagging south during the afternoon, this could be a focus area of isolated to scattered convection. It appears that the best chance for storms could be NW OH once again as the boundary will be hung up in that region and there will be some moisture convergence and air temperatures approaching convective temperatures to help convection to get going. The other favored area will be interior Northeast Ohio for areas from Wooster to Youngstown and south, but less warm temperatures could hinder some coverage. Temperatures will fall again into the upper 60s and lower 70s tonight with dry conditions in a stable air mass. For Saturday, the upper ridge is pushed pretty far south and more zonal flow develops across the Great Lakes region. This may actually allow for more mixing across the entire forecast area, so daytime winds may be up a bit, but dew points may be down, which may sufficiently hinder shower and storm development. Less mixing in interior NE OH and NW PA may allow for some isolated showers and storms but probability seems very low. With less of a blocking ridge aloft, some even warmer air could advect into the area and temperatures on Saturday should return to the widespread 90s and heat index values will once again meander close to 100 degrees. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... A brief trough will push east across a primarily zonal upper level flow during the short term period, briefly shifting the weather pattern from the ongoing pattern. An associated surface low is expected to track northeast through the Great Lakes region which will move a cold front east on Sunday. Models suggest a bit of a slow down in the progression of this boundary which will allow temperatures to climb into the mid to upper 80s on Sunday. The timing of the frontal passage now looks to be during a more diurnally favorable time with modeled MUCAPE values climbing to near 1500 J/kg. The one limiting factor on Sunday is that widespread clouds are expected, but if areas see breaks in clouds, expect the instability to be a bit higher. With this potential widespread convection on Sunday, the primary concerns remain damaging wind gusts, although large hail and an isolated tornado cannot be ruled out given the shear and helicity values in models. In addition, a deep warm cloud layer and PWAT values near 2" will result in extremely efficient rainfall within these storms. Localized flooding may be possible, especially in areas that receive the strongest storms. To highlight this severe weather potential, SPC has issued a Day 3 Marginal Risk for severe weather for areas along and east of I- 71 and WPC has issued a Marginal ERO for far eastern OH and NW PA. The cold front will settle southeast of the area late Sunday night and allow for the remainder of the short term period to be dry as high pressure again builds in. Although it is a cold front moving through, it will not impact temperatures all that much with Monday highs still expected to climb into the upper 80s for areas west of I71, but will be a tad cooler east only climbing into the upper 70s to low 80s. Overnight lows both nights will be a bit cooler dropping into the mid 60s both nights. && .LONG TERM /TUESDAY THROUGH THURSDAY/... High pressure will remain over the area on Tuesday , keeping conditions primarily dry but also increase temperatures also into the mid 90s for western counties and mid 80s for eastern counties. There is a potential for afternoon convection to develop given enough moisture and instability and the positioning of the area within the warm sector. By Tuesday night, models diverge quite a bit in what will happen for the remainder of the long term period. The ECMWF suggests a broad upper level trough that moves across the northern Great Lakes with an associated weak cold front pushing east on Wednesday. The GFS and Canadian however suggest a deeper upper level trough extending over the eastern US with a surface low over the Mississippi River Valley and another over the Great Lakes region. Although the driving mechanisms are different amongst models, there looks to be a consistent chance of showers and storms on Wednesday into Wednesday night before high pressure returns and dries out the area for the end of the long term period. Tuesday looks to be the warmest day during the long term period with temperatures gradually cooling to the low to mid 80s by the end of the period. Overnight lows will follow a similar pattern with temperatures falling into the upper 60s to low 70s Tuesday night, but then cooling into the upper 50s to low 60s by Wednesday night. && .AVIATION /18Z Friday THROUGH Wednesday/... Scattered thunderstorms are developing along the lake breeze boundary this afternoon. The chance for thunderstorms to impact terminals will be highest along the edges of our local area at KTOL and KYNG. As with the past week, these thunderstorms will diminish as we lose daytime heating this evening. Northwest flow with north flow along the lakeshore less than 10 knots will turn light and variable overnight tonight. Higher wind gusts possible in any thunderstorm that moves over a terminal this evening. Wind speeds out of the southwest will increase tomorrow morning to 8-12 knots. Outlook...Thunderstorms will increase in coverage Sunday afternoon with non-VFR conditions possible. && .MARINE... A stalled boundary will linger near the southern shore of Lake Erie today, allowing for generally light and variable winds with the exception of locally high winds and waves in the afternoon and evening with any thunderstorms that develop. Winds will increase to 10-15 knots from the southwest on Saturday as a warm front lifts north of Lake Erie and a cold front approaches from the west. On Sunday, the aforementioned cold front will move east across the area. Winds will briefly increase from the southwest to 15-20 knots ahead of the boundary, gradually shifting to the northwest and weakening to 10-15 knots by Sunday night. This period on Sunday looks to be the next potential time for a Small Craft and Beach Hazard needed, but with uncertainty lingering in the timing of the front, will continue to monitor. High pressure returns late Monday through Tuesday, allowing winds of 5-10 knots to gradually shift and gain more of a southerly component. Generally winds will remain from the south-southwest through Wednesday as high pressure lingers before shifting to gain more of a northerly component on Thursday. Models diverge in timing of boundaries past Wednesday, so will need to continue to monitor those trends in the coming updates. && .CLIMATE... The records for Friday, June 21 through Sunday, June 23 are listed below for our official climate sites. Date Toledo Mansfield Cleveland Akron Youngstown Erie 06-21 100(2022) 96(1988) 95(2022) 97(1933) 98(1933) 95(1933) 06-22 99(1988) 95(1988) 98(1988) 97(1988) 97(1933) 94(1988) 06-23 96(1911) 91(1964) 94(1948) 94(1923) 94(1943) 92(1964) && .CLE WATCHES/WARNINGS/ADVISORIES... OH...Heat Advisory until 8 PM EDT Saturday for OHZ003-006>014- 017>023-027>033-036>038-047-089. PA...Heat Advisory until 8 PM EDT Saturday for PAZ001>003. NY...None. MARINE...None. && $$ SYNOPSIS...Sefcovic NEAR TERM...Iverson/Sefcovic SHORT TERM...Campbell LONG TERM...Campbell AVIATION...Iverson MARINE...Campbell CLIMATE...