Area Forecast Discussion
Issued by NWS Cleveland, OH
Issued by NWS Cleveland, OH
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256 FXUS61 KCLE 191037 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 637 AM EDT Wed Jun 19 2024 .SYNOPSIS... Upper level ridge providing heat for the area remains in place through the end of the week with isolated to scattered shower and storms each day. A weak cold front drops southward into northern Ohio and northwestern Pennsylvania Thursday lifting back northward as a warm front Friday. && .NEAR TERM /THROUGH THURSDAY/... 635 AM Update... Minor temperature edits. No other significant changes. Not as hot for most today, but dewpoints climb higher. Previous Discussion... Dome of high pressure aloft remains anchored over the mid Atlantic coast, so no major changes to the overall airmass in place. Two changes to some of the specifics going into today, however. First is the plume of high level moisture streaming up from the Gulf of Mexico into the southern Great Lakes. This will result in a decrease in the insolation factor today, and will knock a couple degrees off the forecast high temperatures compared to the first two days of the work week. This could also lead to a slight inhibition of convective development with a slightly less diurnal heating factor. That said, with the instability remaining in place, still expecting isolated to scattered convection today, and will peak during the prime heating hours of the day despite the cloud cover. The second part of the forecast that is a bit of a change is that the dewpoints today will increase and have lower 70s dominating the CWA as opposed to upper 60s dominating. So even though the temperatures may not be quite as high, heat indices in the upper 90s to 100 will continue with the higher dewpoints. Will leave the Heat Advisory in place although it is probably a bit of a more marginal call today. For Thursday, a weak cold front drops into the area, with perhaps yet a little more relief to the heat for the far northern zones and could become a focus for convective initiation. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... The heat wave and headlines will continue through at least Friday with extensions into Saturday possibly needed in future updates. Daily afternoon heat indices in the mid to upper 90s to near 100 will remain likely. Not much relief is expected during the overnight periods either with low temperatures in the 70s. Isolated strong thunderstorms are possible in the afternoon and early evening on Friday as moderate to strong instability persists across the southern Great Lakes, aided by a stream of steep mid-level lapse rates and moist low-levels. A very weak cold front may stall in the vicinity of northern OH which could also be the basis for convective initiation. Weak shear less than 20 knots is expected, so anticipate any thunderstorms that do develop will be poorly organized and generally short-lived. These storms will primarily carry a damaging wind risk given steep low-level lapse rates and large theta-e differences. Locally heavy rain is also possible. Storm chances appear to be trending downwards for Saturday afternoon as deeper mixing into mid-level dry air is possible, evident by dew points dropping into the 60s. However, this would also favor less cloud cover and thus higher temperatures reaching into the mid to upper 90s. Future shifts may need to evaluate the Heat Advisory extension into Saturday. && .LONG TERM /SATURDAY THROUGH TUESDAY/... The better potential for more organized strong thunderstorms will arrive on Sunday as a well-defined upper-level low moves east across the Upper Great Lakes, extending a surface cold front through the area. Moderate instability appears to remain in place combined with 30 to 35 knots of southwesterly mid-level flow. This system will bring an end to the extreme heat wave as behind the front, cooler and more seasonable weather will arrive, with temperatures in the low to mid-80s on Monday. Anticipate dry weather conditions as a surface high briefly builds in across the Great Lakes. However, the respite from the heat appears brief as another upper- level ridge begins to build across the Central CONUS by Tuesday. Above-normal temperatures will return on Tuesday with highs in the upper 80s to lower 90s, albeit without the oppressive humidity. && .AVIATION /12Z Wednesday THROUGH Sunday/... The TEMPO TSRA groups and timing are on the lower confidence side as there is not much consensus on initiation timing which could vary by a few hours for different terminals. AMDs probably needed to account for this, but expect cumulus congestus and towering cumulus once again for the whole area today, especially during peak heating in the afternoon hours. Wind gusts to 30kts possible in TSRA. Outside of thunderstorms, winds SSW less than 10kts. Outlook...Primarily VFR expected through Friday. Isolated to scattered thunderstorms and non-VFR conditions are possible again Thursday and Friday afternoons. && .MARINE... A generally quiet marine forecast is in store for Lake Erie as a large upper-level ridge remains across the Eastern CONUS, resulting in limited surface flow. Only concern will be in the afternoon and early evening hours this week as daily isolated to scattered thunderstorms could produce strong wind gusts. Will need to monitor wind and wave trends towards the end of the weekend and into early next week as a cold front moves east across the area on Sunday. Ahead of the front, southwest winds of 15 to 20 knots are possible, shifting towards the northwest behind the front on Monday, 10 to 15 knots. && .CLIMATE... A prolonged stretch of hot weather is expected this week. Temperatures are forecast to approach or exceed record highs on several days. The records for Tuesday, June 18 to Friday, June 21 are listed below for our official climate sites. Date Toledo Mansfield Cleveland Akron Youngstown Erie 06-19 98(1995) 94(1994) 92(1995) 94(1994) 94(1994) 92(1931) 06-20 98(1953) 94(1988) 96(1988) 95(1933) 95(1933) 92(2016) 06-21 100(2022) 96(1988) 95(2022) 97(1933) 98(1933) 95(1933) && .CLE WATCHES/WARNINGS/ADVISORIES... OH...Heat Advisory until 8 PM EDT Friday for OHZ003-006>014-017>023- 027>033-036>038-047-089. PA...Heat Advisory until 8 PM EDT Friday for PAZ001>003. NY...None. MARINE...None. && $$ SYNOPSIS...26 NEAR TERM...Campbell/26 SHORT TERM...Kahn LONG TERM...Kahn AVIATION...26 MARINE...Kahn CLIMATE...