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Area Forecast Discussion
Issued by NWS Cleveland, OH
Issued by NWS Cleveland, OH
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567 FXUS61 KCLE 172358 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 758 PM EDT Wed Jul 17 2024 .SYNOPSIS... A cold front will move southeast of the area tonight as a ridge builds from the north-central United States and vicinity before settling over the eastern Great Lakes and Upper Ohio Valley this weekend. && .NEAR TERM /THROUGH THURSDAY NIGHT/... 745 PM Update... A few showers may persist along a trough axis over the next few hours, but otherwise expect a downward trend in shower coverage through this evening. Lake-enhanced clouds could move in later this evening, but latest guidance suggests that the cooler 850mb temperatures and the greatest cloud cover may hold off until mid-morning Thursday. Will need to continue to keep an eye on upstream cloud cover (which isn`t widespread at the moment) and adjust the forecast as needed. No changes needed with this update outside of making minor adjustments to PoPs based on latest radar trends. Previous Discussion... Cyclonic flow aloft and embedded disturbances affect the eastern Great Lakes and Upper OH Valley, including our CWA, through Thursday night. The cyclonic flow aloft is expected to shift from W`erly to NW`erly late Thursday afternoon through evening as a prominent mid/upper-level trough axis advances SE`ward across our region. At the surface, a cold front in vicinity of a New Castle, PA to Mount Vernon, OH line at 3:30 PM EDT continues moving SE`ward and exits the rest of our CWA by this early evening. Behind the front, a ridge associated with a cooler/less humid air mass builds from the north-central United States and vicinity. A lowering/strengthening subsidence inversion accompanying the ridge will allow our sky to clear gradually from northwest to southeast through the near-term period. However, 850 mb temperatures cooling to near 9C to 10C over ~24C Lake Erie and sufficient low-level moisture will allow lake- effect stratocumuli to develop over and generally southeast of Lake Erie late this evening through the mid-morning hours of Thursday. The aforementioned low-level cold/dry air advection regime will contribute to cooler-than-average temperatures, overall. Overnight lows tonight reach mainly the mid 50`s to lower 60`s around daybreak Thursday. Highs are expected to reach the 70`s late Thursday afternoon. Overnight lows are forecast to reach the lower 50`s to lower 60`s around daybreak Friday. The warmest of these lows are expected over/very near Lake Erie. Primarily fair weather is expected during the near-term period. However, daytime heating of the relatively-humid boundary layer ahead of and behind the cold front has allowed mixed layer CAPE to build to weak to moderate magnitudes amidst moderate effective bulk shear in our CWA. Multicell showers/thunderstorms along the surface to roughly 850 mb portion of the cold front will exit our region generally to the east through this early evening. In addition, isolated multicell showers/thunderstorms associated with a shortwave disturbance`s attendant surface trough axis/wind shift will overspread our northwest OH counties from the west late this afternoon/early this evening. This convection is expected to persist generally E`ward into north-central and portions of northeast OH before dissipating around sunset this evening, in response to boundary layer stabilization via nocturnal cooling. Lastly, lake-effect stratocumuli streaming generally SE`ward from Lake Erie may produce rain showers during the predawn through mid-morning hours of Thursday. These rain showers are expected to be light since a lowering/strengthening subsidence inversion and low- level dry air advection will likely limit lake-induced CAPE to weak magnitudes. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... Quiet and seasonable weather is expected for the short term period as high pressure remains firmly in place. It may feel like late Spring rather than mid-Summer at times with dew points in the 50s under mostly sunny skies. Temperatures will be the coolest on Friday night, with lows bottoming out in the 50s. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... Mainly quiet weather will continue for the long term period as weak surface high pressure remains in place, though chances for showers and storms will percolate back into the region by Tuesday and Wednesday as humidity increases ahead of a weak upper-level trough. Not anticipating anything too organized on Tuesday and Wednesday as mid and upper flow remain weak, though high atmospheric moisture content and slow-moving storms could result in localized heavy rain. Temperatures are expected to remain seasonable through the long term period. && .AVIATION /00Z Thursday THROUGH Monday/... VFR should persist at all TAF sites for at least the next several hours before lake-enhanced clouds begin to move in later tonight and especially during the day Thursday. As of now, guidance isn`t super aggressive with lower ceilings; instead of MVFR ceilings, it`s possible that ceilings remain around 4-5kft AGL and end up being more scattered since lake-induced instability will be marginal. The highest cloud cover will likely be mid-morning through Thursday afternoon when the coolest 850mb temps arrive from the north. Can`t rule out some patchy fog at southeastern terminals overnight where winds become light overnight (including KCAK and KYNG), but the better opportunity for non-VFR conditions will lie to the southeast of the forecast area. Would like to see how fog develops before introducing to any TAFs. Winds will be out of the north at 6 to 12 knots, but as stated above, winds at KMFD/KCAK/KYNG will likely drop below 5 knots overnight tonight. Outlook...VFR expected Thursday afternoon through Monday. && .MARINE... A mainly quiet marine period is in store through the weekend with no headlines anticipated. Only timeframe we`ll need to monitor for slightly higher winds/waves will be behind a cold front tonight into Thursday, as winds shift towards the north, around 15 knots, ushering in waves 2 to 4 feet. Following Thursday, surface high pressure is expected to remain firmly in place across the region through the weekend, with periods of light flow less than 10 knots expected. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. NY...None. MARINE...None. && $$ SYNOPSIS...Jaszka/Maines NEAR TERM...Jaszka/Maines SHORT TERM...Kahn LONG TERM...Kahn AVIATION...Maines MARINE...Kahn