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Area Forecast Discussion
Issued by NWS Cleveland, OH
Issued by NWS Cleveland, OH
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383 FXUS61 KCLE 161413 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 1013 AM EDT Tue Jul 16 2024 .SYNOPSIS... A frontal boundary will settle across the Lower Great Lakes today before pushing southeast across the area as a cold front Tuesday night into early Wednesday. High pressure will build in from the west Wednesday night through the end of the week. && .NEAR TERM /THROUGH WEDNESDAY/... 10:10 AM EDT Update... A prominent cyclonic MCV centered over southern ON, near the north-central Lake Erie shore, is expected to move ENE`ward to far-northern NY, just east of Lake Ontario, by this early evening. Simultaneously, the attendant mesoscale surface low is expected to track generally E`ward from western Lake Ontario to far-northern NY. Moist isentropic ascent associated with the MCV`s warm conveyor belt may release enough instability, including elevated CAPE, to trigger isolated showers and thunderstorms over/near central and eastern Lake Erie through this early afternoon. In addition, SW`erly to NW`erly surface winds gusting up to 25 to 35 knots and associated with the mesoscale surface low`s cyclonic circulation/diurnal convective mixing of the boundary layer tapping into stronger flow aloft are forecast to ease by this early afternoon as the MSLP gradient relaxes in the wake of the low. Stabilizing subsidence behind the MCV is expected to promote primarily fair weather through sunset this evening. However, will have to watch expected lake breeze development within several miles of Lake Erie this afternoon through early evening. The lake breeze front may trigger a few showers/thunderstorms amidst weak to moderate boundary layer CAPE, sizable DCAPE, and moderate effective bulk shear. Thus, a few severe thunderstorms with damaging convective gusts are possible along and downstream (i.e. generally east) of this expected lake breeze front. Will also have to monitor our northern OH counties, south of roughly U.S. Route 30, where model guidance appears to suggest low-level convergence/moist ascent along mesoscale fronts related to differential diurnal heating may trigger a few showers/thunderstorms amidst the aforementioned thermodynamic/kinematic environment favorable for strong to damaging convective gusts. Will continue to monitor trends in obs and model guidance, including CAM`s, closely. Made minor adjustments to POP`s/QPF/sensible WX grids per aforementioned trends. Rest of forecast remains valid. Please see discussion below for further details. Previous Discussion... A line of storms west of I-77 continued to move across the area, producing very isolated strong wind gusts. This activity should be out of the area by 12Z. Meanwhile, a wake low moving to our north has been responsible for locally strong winds west of I-71 this morning, with observed gusts of 35kts at KTOL and 33 kts at KFDY. Should see this activity spread east and may see brief 1-3 hour period of gusty winds before winds gradually diminish through the day today. Additional isolated to scattered showers and thunderstorms may develop this afternoon/evening, though trends do not look very favorable for severe weather despite most model guidance forecasting moderate instability (1500-2000 J/kg MUCAPE) paired with marginal deep layer shear (20-25kts). Subsidence in the wake of an MCV will likely prevent too many robust updrafts in our forecast area this afternoon. Additionally, most CAM modeled reflectivity have an MCS (and possibly another MCV) developing over Illinois and moving east to the south of our forecast area by this evening into tonight. If an MCV does develop to our south, this could potentially be a focus for additional shower/thunderstorm develop this evening into tonight. For now, most of the area in a marginal risk for severe weather (level 1/5) but it`s a pretty low confidence forecast at this point. Strong winds gusts would be the most likely weather hazard. By tomorrow a cold front moves in from the northwest. Most models have a broken line of showers and thunderstorms developing along this front during the afternoon hours. There will be much less instability (~750-1000 J/kg MUCAPE) but greater deep-layer shear (30-50 kts, depending on the model). The 06Z HRRR/NAM Nest both have weak updraft helicity tracks but it seems unlikely for this to happen. Even so, this will be worth monitoring. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... If you`re tired of the warm and humid weather with low- predictability convection then this portion of the forecast is for you. Wednesday`s cold front may still be exiting during the evening so do linger low chances for showers across our southeast the first part of Wednesday night. Otherwise, a seasonably deep longwave trough will be settling into the Great Lakes Wednesday night into Thursday before shifting east-northeast into Quebec and New England to end the work week. We may actually get lake effect clouds and a few sprinkles Thursday morning as the trough digs in amid strong cold air advection over the lake. Otherwise, strong high pressure builds in Thursday night and persists through the end of the work- week bringing mainly clear and refreshingly cooler conditions. Look for highs in the low to mid 70s on Thursday and in the mid to upper 70s on Friday with dew points falling safely into the 50s by Thursday afternoon. Overnight lows will likely still be in the low to mid 60s Wednesday night but should get into the 50s outside of the immediate lakeshore and denser urban corridors Thursday and Friday nights. As the prior discussion said, open those windows. && .LONG TERM /SATURDAY THROUGH MONDAY/... Strong high pressure remains in control through Saturday night as we remain beneath upper-level confluence on the backside of the departing longwave trough. High pressure slowly weakens Sunday into Monday as the trough to our northeast continues to depart, with the next modest trough deepening across the Mississippi Valley by the beginning of next week, encouraging broad and light south- southwesterly flow over our region. High confidence in dry weather through Saturday night. The weakening high pressure and some moisture return on Sunday make it a bit harder to completely rule out any chance for an increase in clouds and perhaps a stray shower but odds in any one spot are still under 20%, precluding a forecast mention. No major systems on Monday but gradual return flow continues, so do begin including some 20% POPs (which does not garner a forecast mention in our text products that far in the future). Overall, very low impact weather for this period. Highs will return to the low to mid 80s through the weekend with overnight lows ranging from the upper 50s to mid 60s Saturday and Sunday nights, with low to upper 60s in the forecast for Monday night. && .AVIATION /12Z Tuesday THROUGH Saturday/... Brief MVFR ceilings may move across the area this morning, with areawide VFR expected this afternoon/evening. Isolated to scattered showers and thunderstorms are possible this evening into tonight. For now, went with VCSH and removed any mention of thunderstorms, as confidence in the occurrence of thunder has decreased from previous TAF issuance. Some MVFR ceilings may develop late tonight, especially across the southern part of the forecast area (e.g. at TAF sites such as KMFD, KCAK, and KYNG). Winds briefly increase to 10-15 knots this morning with gusts of up to 20-25 knots (perhaps even very brief 30 knot gusts). These winds should diminish by the afternoon, remaining under 10 knots through the rest of the TAF period. Outlook...Non-VFR possible with isolated showers and thunderstorms on Wednesday. && .MARINE... Similar to yesterday an MCV (small low pressure generated by thunderstorms) is currently over southeastern Michigan and will move over or just north of Lake Erie this morning through early this afternoon. Several hi-res models depict enhanced west-southwest winds of 20 to perhaps briefly 30 knots moving west-east across the lake on the south side of the MCV, and are already seeing that across Northwest OH and the waters off of Toledo. Given that, have issued a short-fused Small Craft Advisory until noon west of Vermilion and 4 PM farther east. Otherwise, mainly light winds are expected on the lake over the next several days. In decent cool air advection northerly winds will increase to around 15 knots late Wednesday night into early Thursday which will build some 2-4 footers in the nearshore waters. Will closely monitor that wind forecast as an uptrend could result in a Small Craft Advisory, though the current wind/wave forecast is below criteria. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...Beach Hazards Statement until 4 PM EDT this afternoon for OHZ011-012-089. PA...Beach Hazards Statement until 4 PM EDT this afternoon for PAZ001. NY...None. MARINE...Small Craft Advisory until noon EDT today for LEZ142>144. Small Craft Advisory until 4 PM EDT this afternoon for LEZ145>149. && $$ SYNOPSIS...Saunders NEAR TERM...Jaszka/Saunders SHORT TERM...Sullivan LONG TERM...Sullivan AVIATION...Saunders MARINE...Sullivan