Area Forecast Discussion
Issued by NWS Cleveland, OH
Issued by NWS Cleveland, OH
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655 FXUS61 KCLE 281956 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 356 PM EDT Fri Jun 28 2024 .SYNOPSIS... Low pressure will track from the northern Plains into the northern Great Lakes tonight, lifting a warm front through the region by Saturday morning. A trailing cold front will sweep across the region Saturday night into Sunday morning as the low tracks into Quebec. High pressure will build into the region Sunday and Monday before moving east Tuesday. && .NEAR TERM /THROUGH SATURDAY NIGHT/... Very active weather is still expected late tonight and Saturday with areas of heavy rainfall as well as a few severe storms likely. The heavy rain and flooding threat is still higher confidence than the severe weather threat, but there is uncertainty regarding where the heaviest, most persistent thunderstorms may set up. See details below. Water vapor loops this afternoon show a strong mid/upper shortwave trough and associated closed low moving from the northern Rockies into the northern Plains. This shortwave will progress into the northern Great Lakes late tonight and Saturday morning before becoming absorbed into a broader mid/upper trough digging down across the Great Lakes by Sunday. The associated surface low, currently over northern Minnesota, will cross the UP of Michigan tonight before exiting into Quebec Saturday night, dragging a strong cold front through the region Saturday night into Sunday morning. Upstream radar and surface observations show a sign of what`s to come late tonight and Saturday, with strong warm/moist advection bringing dew points into the 70s in the warm sector across a large area of the corn belt, as well as widespread showers and elevated thunderstorms driven by isentropic ascent ahead of the warm front. This warm front will slowly lift east-northeastward across the region tonight into Saturday morning, with strong warm/moist theta e advection tapping into the aforementioned rich low-level moisture to the west and southwest. Expect dew points to rise quickly this evening and tonight, with most dew points touching 70F by 12Z Saturday. There is no doubt that the environment will become juicy in a hurry, but the location of the heaviest, most widespread axis of convection is uncertain. Regarding heavy rain/flooding details, A 40-50 knot west- southwesterly low-level jet will feed high theta e air and elevated instability into the region, with associated isentropic ascent driving elevated convection ahead of the slowly lifting boundary, but CAMS are struggling to pinpoint where the best axis will set up. There is a wide range of possibilities from over Lake Erie to over the southern and eastern tier of counties, so held off on a Flood Watch for now given the uncertainty. What is certain is that any thunderstorms late tonight and Saturday morning will contain highly efficient (torrential) rainfall rates given PWATs rising to 2 to 2.3 inches (maximum daily value of climatology), very deep, saturated warm cloud depths, and low LCL heights of 400-800 m to minimize evaporation. CAMS suggest some training or repeated rounds of convection is possible before the warm frontal boundary lifts NE, and with the aforementioned environment supporting rainfall rates in excess of 3 inches per hour, flash flooding is likely in areas that see training or multiple rounds despite current 3 and 6 hour FFG`s being high. Will wait to see where the axis starts to set up tonight to determine where the greatest flooding threat will be, but heavy rainfall rates are possible anywhere. Regarding the severe weather potential Saturday afternoon and evening, this is far more conditional and uncertain. As the warm frontal boundary lifts ENE across the region Saturday morning, it is likely to slow over NE Ohio and NW PA. NAM and RAP forecast soundings and plan views suggest impressive veering with height near the boundary leading to curved hodographs and 300-400 m2/s2 of low- level (0-1Km) SRH. This along with low-level shear of 30+ knots and deep layer effective shear of 40-50 knots in the morning near the warm front could support an isolated tornado or two, aided by the low LCL heights as well. However, instability and time of day are the biggest limiting factors. Forecast soundings suggest elevated CAPE over 1000 J/Kg but very little SBCAPE available, so it`s possible that we just see some elevated rotation along with heavy rainfall. If severe weather occurs, there is a better chance for the afternoon and evening as the area gets fully into the warm sector behind the warm front. Latest CAMS are suggesting a lull most of the afternoon which could allow for breaks in the overcast and greater heating/instability. If this occurs, then scattered severe thunderstorms will redevelop ahead of the cold front and move across the region from NW to SE during the afternoon and evening. These storms could produce damaging winds, an isolated tornado or two, and additional heavy rainfall given deep layer shear staying marginally favorable (30-35 knots) along with marginally favorable low-level shear of 20+ knots and low-level SRH of 100-200 m2/s2. However, there is uncertainty in how much redevelopment will occur since there could be extensive cloud cover and outflow lingering from the morning convection. Some CAMS show very little redevelopment or redevelop the convection SE of the area. At this time, the SWODY2 slight risk still looks reasonable given the shear that could potentially take advantage of greater heating, but again, very conditional. Any showers and thunderstorms will quickly end from NW to SE Saturday night as the cold front passes through the region and drier air works in behind it thanks to broad surface high pressure over the Upper Midwest. Highs Saturday will range from the low/mid 80s in most areas, but more precip could keep NW PA and NE Ohio in the upper 70s to around 80. It will be oppressively humid with dew points in the low to mid 70s. The cooler air will start to come in Saturday night with lows in the low to mid 60s. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... An upper level trough will be over the Great Lakes region extending into southern Ontario and Quebec during the later part of the weekend. High pressure at the surface will be centered over the Upper Midwest on Sunday slowly building into the region. Cooler air will advect in with a northwesterly flow Sunday. There will be mix of sun and clouds across the area with more cloud cover down downwind of Lake Erie. There also could be a few isolated lake effect rain showers early Sunday morning before the atmosphere dries out. Afternoon temperatures will reach the lower and middle 70s on Sunday. High pressure will continue to build over the region Sunday night into Monday. Skies will clear out Sunday evening and overnight low temperatures will fall into the lower 50 middle 50s away from the immediate lakeshore. Monday will be very nice day with plenty of sunshine and light winds with the center of high pressure nearby. Afternoon temps will be in the lower to middle 70s Monday. && .LONG TERM /TUESDAY THROUGH FRIDAY/... A summertime ridge of high pressure will develop across the Lower Ohio Valley and Mid-Mississippi River Valley regions by the middle of next week. Our area will be on the edge of this ridge. Southerly flow will return on Tuesday with a return to summer like temperatures climbing into the middle and upper 80s. The humidity will also start returning Tuesday into Wednesday. A shortwave trough will move through the Upper Great Lakes region on Wednesday with a trailing cold front. Wednesday will likely be the hottest day of next week with temperatures reaching the upper 80s and lower 90s. A weak cold front will move into the area next Wednesday night with scattered showers and thunderstorms. This frontal boundary may stall out from west to east over Ohio Thursday into Friday with multiple rounds of showers and storms possible towards the end of next week. High temperatures will remain in the middle to upper 80s late next week. && .AVIATION /18Z Friday THROUGH Wednesday/... VFR will continue the rest of today into tonight, but cigs will gradually lower this evening and tonight as a warm front and associated showers and thunderstorms approach from the west. There is a fairly consistent signal for widespread showers and thunderstorms late tonight into Saturday morning, but uncertain in where the heaviest and most widespread axis of thunderstorms will set up. Any thunderstorms will produce torrential rainfall rates and resultant low cigs and vis. At this time, stayed with widespread showers/storms and MVFR conditions spreading in from west to east in the 06-12Z timeframe. IFR is possible at times as well, but this will all be fine tuned once we see where the axis sets up. There will be a solid warm sector behind the warm front late Saturday morning through the afternoon, and this is leading to far less coverage of showers/storms during the afternoon than previously thought, so kept precip mentions to VCSH in the afternoon with cigs improving to VFR for sites along and west of I-71. S winds of 5-10 knots this evening into early tonight will become SW and increase to 10-20 knots late tonight and Saturday morning with gusts of 20-25 knots at times. Outlook...Non-VFR possible in showers and thunderstorms Saturday afternoon into Saturday night. Non-VFR possible in showers and thunderstorms Tuesday night and Wednesday. && .MARINE... Southerly, offshore flow will continue at 10 to 15 knots tonight. The flow will become southwesterly on Saturday and increase 15 to 20 knots ahead of an approaching cold front. The front will move across Lake Erie Saturday evening. Winds will shift from the northwest and onshore around 15 knots Saturday night through Sunday afternoon. We could briefly reach SCA conditions for a few hours Saturday night into Sunday behind the front but confidence is uncertain at this time. Waves will be higher along the lakeshore by Saturday evening and overnight. High pressure will build in Sunday night into Monday. Winds will be northerly Sunday night 10 to 15 knots. On Monday, winds will shift from the northwest around 10 knots becoming light and variable by Monday evening. South to southeasterly winds around 10 knots will return on Tuesday and further increase 15 to 20 knots from the southwest by next Wednesday. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. NY...None. MARINE...None. && $$ SYNOPSIS...Garuckas NEAR TERM...Garuckas SHORT TERM...Griffin LONG TERM...Griffin AVIATION...Garuckas MARINE...Griffin