Area Forecast Discussion
Issued by NWS Cleveland, OH
Issued by NWS Cleveland, OH
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900 FXUS61 KCLE 031649 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 1249 PM EDT Mon Jun 3 2024 .SYNOPSIS... High pressure builds in today before departing to the east tonight. A warm front will lift north across the area tonight. A cold front extending from low pressure north of the Great Lakes will move east across the area late Wednesday followed by a trough lingering across the region trough the weekend. && .NEAR TERM /THROUGH TUESDAY/... 12:30 PM Update... Low clouds and mist continue to slowly dissipate over NE Ohio and NW PA, but some 5 mile visibilities linger in a few spots. Skies should become mostly sunny in all areas by 19Z, so afternoon temperatures and sky cover still look good with most areas spiking into the mid 70s once skies clear. 9:30 AM Update... The forecast remains on track this morning with no changes needed. Fog is slowly burning off, but it will take until 15 or 16Z for the mist and low clouds in NE Ohio and NW PA to completely go away, but the worst of the visibilities are done. It will mainly keep things dreary over the next few hours in the NE areas. Most areas will see sunshine by early to mid afternoon as the boundary layer finally mixes out. 6:30 AM Update... The entire region has been engulfed in low stratus and patchy fog. The most persistent dense fog has been along and south of US-30 and in parts of North-central and Northwest Ohio near Lake Erie, though there have been patchy 1/4SM obs elsewhere. A special weather statement was issued earlier for area generally along and west of I-71 where patchy dense fog was observed earlier. Patchy dense fog elsewhere shouldn`t last much longer now that sunrise has occurred, maybe through 12-13Z or so. Previous Discussion... Light and variable winds along with decent low- level moisture has allowed for a variable combination of low stratus and areas of fog (locally dense) across the area. Dense fog has been most persistent in the southern part of the forecast area south of US-30 in central Ohio. Elsewhere, visibility has been more variable. Consideration will be made over the next hour or two to determine the need for a dense fog advisory and/or a special weather statement to cover the fog. Fog will last through about 12-14Z before quickly dissipating, giving way to a scattered cumulus field through the early afternoon, before this cumulus field also dissipates (by mid- late afternoon) as the boundary layer mixes into the dryer air aloft. With high pressure overhead and temperatures warming into the low 80s, a lake breeze is likely to develop, which may actually make some decent inland progress due to weak environmental background pressure gradient. High pressure departs to the east by tonight, with southerly flow developing on the backside. This should warm temperatures into the mid-upper 80s by Tuesday afternoon. Dew points in the low to mid 60s will support some marginal instability, though dry air aloft and modest MLCIN should prevent any convection from developing, though can`t completely rule it out. Currently have ~20% PoPs west of I-77 after 21Z, though this area of PoPs is very low confidence. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... We`ll start the short term with a ridge over the eastern US and a trough beginning to dig into the Plains Tuesday night. By Thursday and Thursday night this trough will amplify and shift east, with good agreement that a deep and closed-off trough will be sitting over the Great Lakes to end the week. At the surface, respectably deep low pressure (near or a bit deeper than 990mb) will drift from Saskatchewan into Ontario through the period. A re-enforcing warm front will lift across the area Tuesday night into early Wednesday, with a strong cold front pushing across the local area late Wednesday or Wednesday night. In terms of sensible weather, some showers or thunder are possible Tuesday night and early Wednesday in association with the re- enforcing warm front and a weak shortwave. This activity will be moving through at a diurnally unfavorable time and forcing isn`t especially strong, so it should be on a weakening trend if it makes it in Tuesday night. Do have some chance POPs generally west of I-77 for Tuesday night with slight chances farther east. POPs continue to expand east and increase on Wednesday. The main cold front is not expected to swing through until the afternoon and evening hours, though a moist airmass and generally increasing forcing for ascent ahead of the digging upper-level trough may support some pre-frontal showers and storms, perhaps a continuation of whatever activity begins drifting in from the west Tuesday night. Have the highest POPs (categorical/80%+ area-wide) focused on Wednesday afternoon and evening with the main cold frontal passage. There should be a period of drier weather immediately behind the front Wednesday night into early Thursday, though scattered showers and storms will quickly return to the forecast off and on beginning on Thursday due to a combination of weak instability beneath cold air aloft and a series of shortwaves rotating around the larger upper trough. Lows Tuesday night will generally stay well into the 60s with a few spots struggling to cool below 70. Highs on Wednesday have been lowered a touch from the prior forecast due to uncertainty regarding pre-frontal showers and storms, though still are near or a bit better than 80 degrees with a muggy airmass expected to be in place. Lows Wednesday night will generally settle into the low to mid 60s, with highs on Thursday likely capped in the mid to upper 70s as dew points cool into the 50s. Most of the area should dip into the 50s Thursday night. Severe weather and flooding concerns are not extremely high for the cold frontal passage Wednesday afternoon/evening but aren`t zero either. The airmass ahead of the front will be quite humid, characterized by dew points in the mid to upper 60s and precipitable water (PWAT) values of 1.60-1.90", which is close to climatological max values for early June per Wilmington, OH observed sounding climatology. While shear will not be overwhelmingly strong, guidance ranges from 25 to nearly 40 knots of effective bulk shear across the area Wednesday afternoon. This is sufficient for loosely organized clusters and lines on the lower end and more organized lines/bows (and perhaps a transient supercell) on the higher end. The main limiting factor for severe potential will be thermodynamics, with poor mid-level lapse rates and potential for pre-frontal precip both making it questionable how much instability we can develop on Wednesday. If more heating occurs moderate instability would develop, which would point to at least a marginal wind damage threat. Regardless, the poor mid-level lapse rates suggest a skinny CAPE profile, favoring efficient rain rates with any storms. Feel a marginal risk for excessive rainfall as presented by the WPC is reasonable, suggesting a bit of potential for localized heavy rain and flash flooding, with the main concern being in urban areas or if any spot sees localized training convection. The SPC does not currently have any severe weather risk areas outlined for Wednesday, though do believe there`s room for an eventual marginal risk if sufficient instability develops, as has been consistently shown by Colorado State machine learning severe weather forecast guidance. && .LONG TERM /FRIDAY THROUGH SUNDAY/... General troughing will persist over the Great Lakes and Northeast through the weekend. Models do not agree on how quickly the core of the trough shifts east, though cooler than average temperatures along with occasional chances for scattered showers/storms remaining in the forecast through the weekend either way. We should see any washouts in this type of pattern, though any shortwave rotating through the larger upper-level trough will be a potential focus for scattered rain chances. Details will be refined as we get closer. && .AVIATION /12Z Monday THROUGH Friday/... IFR and lower conditions with FG/BR and low stratus are being observed across the entire region except the I-75 corridor where MVFR/VFR conditions persist (despite being surrounded in all four directions by IFR conditions). Fog has occasionally been dense in some locations this morning, especially south of US-30 and in some spots near Lake Erie. Fog should quickly dissipate through 13Z-14Z this morning, giving way to low IFR/MVFR clouds that should eventually transition to a scattered cumulus by early afternoon. This cumulus should also gradually dissipate by mid-late afternoon as the boundary layer mixes with dry air aloft. Mostly clear skies with the occasional high cirrus is expected the rest of this evening and tonight. Light and variable winds of 5 knots or less generally expected through the TAF period, except for an afternoon lake breeze for locations within ~20 miles of Lake Erie where onshore flow of 5-10 knots is expected between approximately 18-23Z. Outlook...Non-VFR is expected with periods of showers and thunderstorms Wednesday and Wednesday night. Non-VFR will be possible with scattered rain showers and isolated afternoon thunderstorms Thursday through Friday. && .MARINE... Fairly tranquil marine conditions are expected today and Tuesday. Onshore winds may reach 10-12 knots for a few hours this afternoon across the western basin. East-southeast will increase to 10-15 knots for a few hours Tuesday afternoon and evening ahead of a re- enforcing warm front. Otherwise, winds will be under 10 knots. There is a low risk for a thunderstorm over the lake Tuesday night. More active conditions are expected Wednesday through Friday with gradual improvement this weekend. A cold front will cross the lake Wednesday afternoon. Scattered storms are likely over the lake along and ahead of the cold front Wednesday. Winds will turn west- southwest Wednesday night and Thursday behind the front and west- northwest Thursday night through Friday night behind a secondary trough. Winds will increase to 15 or so knots at times Wednesday night through Friday night. A period or two of 20 knot winds is likely at some point late Thursday through Friday night, which would build waves and warrant a Small Craft Advisory. Guidance disagrees on when exactly the strongest winds will occur so we don`t have any winds over 20 knots in the forecast yet, though would be surprised if we don`t need headlines at some point towards the end of the week, especially across the central and eastern basin. The pressure gradient should slowly relax this weekend though west winds may maintain some wave activity, even if sub-headline. A risk for isolated thunderstorms persists over the lake off and on through the weekend due to cold air aloft and a series of weak disturbances rotating through a large upper trough over the region. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. NY...None. MARINE...None. && $$ SYNOPSIS...Saunders NEAR TERM...Garuckas/Saunders SHORT TERM...Sullivan LONG TERM...Sullivan AVIATION...Saunders MARINE...Sullivan