Area Forecast Discussion
Issued by NWS Cleveland, OH
Issued by NWS Cleveland, OH
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299 FXUS61 KCLE 111743 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 143 PM EDT Thu Jul 11 2024 ...18z TAF Aviation Forecast Update... .SYNOPSIS... A trough will linger near Lake Erie this morning before high pressure builds into the southern Great Lakes this afternoon and persists through tonight. A weak trough will cross the region Friday into Friday night followed by high pressure returning Saturday. A warm front will approaching from the west Sunday. && .NEAR TERM /THROUGH FRIDAY/... 9:35 AM Update... The only minor adjustments we made to the near term hourly forecast was tweaked the cloud cover and the slight POPs through the early afternoon hours. We may hold on to the lake effect clouds a little longer into the afternoon than the previously forecast had indicating over far NEOH and NWPA. Otherwise, the rest of the forecast is on track with no other changes needed at this time. 6:30 AM Update... Increased PoPs over NE Ohio and NW PA over the next few hours to account for the lingering surface trough and light lake enhanced showers. Otherwise, the forecast remains on track. Original Discussion... Light showers and drizzle continue early this morning from north central Ohio into NE Ohio and NW PA. They are not amounting to much more than a trace to up to a tenth of an inch, but they are keeping things wet with a muggy feel to the air. The light rain is being driven by wraparound moisture on the backside of the remnant surface low from Beryl, currently centered near Lake Ontario, a weak surface trough near the south shore of Lake Erie, and weak lake induced instability given an 8-10 C lake to 850 mb delta T and northwesterly boundary layer flow. The old surface low will continue to fill and move across New England today allowing surface high pressure centered over the western Great Lakes this morning to build over the southern Great Lakes this afternoon and tonight. This will bring a gradual end to the showers this morning along with clearing skies from west to east, but lingering moisture and the surface trough will make it a very slow process in far NE Ohio and NW PA, so held onto slight chance to chance PoPs into the early afternoon. Even NE Ohio and NW PA should see sunshine by late afternoon as the drier air finally wins out. The clearing skies and lower dew points will allow for a cooler night tonight, so the air conditioners can get a break. For Friday, a stubborn mid/upper closed low over the Upper Mississippi Valley will open up into more of a shortwave trough and finally swing into the central Great Lakes, with an associated surface trough moving into western Ohio. Weak warm air advection ahead of this feature combined with mid/upper subtropical ridging over the Mid Atlantic coast building slightly westward will bring a quick return to warmer and more humid conditions Friday. Strong boundary layer heating of the increasingly moist low-level airmass will generate weak to moderate instability (500-1000 joules of MLCAPE), so expect a few widely scattered showers and thunderstorms to develop in NW and north central Ohio near the surface trough, especially from mid morning into the afternoon. Shear will be very weak, generally under 20 knots in the 0-6 Km layer, so any convection is not expected to be severe or very organized. It will be pulse-type convection that will move slowly and be relatively short-lived. Any convection will dissipate Friday evening. Highs in the mid 70s to low 80s today will warm into the mid to upper 80s Friday. Lows will fall into the low 60s tonight, with a few upper 50s in interior NW PA. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... High pressure overhead on Friday night gradually drifts east to the mid-Atlantic region by Saturday, which should result in largely quiet conditions through at least Saturday night. There is a low chance for isolated showers and thunderstorms but confidence wasn`t high enough to quite put it in the forecast. Southwest flow behind the departing high will result in gradually increasing temperatures and moisture with mid to upper 80s expected on Saturday. Northwest flow aloft develops on Sunday with subtle shortwave troughs expected to traverse the Great Lakes region Sunday onward. Heat and humidity continue to build with temperatures touching 90 by Sunday afternoon. PoPs increase to the 20-40% range Sunday and Sunday night with timing greatly depending on shortwave timing. Thunderstorms that occur in the afternoon/evening would likely pose at least a low severe weather threat as most models have pretty decent instability with low but sufficient deep layer shear. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... Northwest flow pattern continues through the long term with several shortwaves expected. Heat and humidity remains relatively unchanged with temperatures in the low 90s and dew points in the low 70s, combining for max heat indices in the mid 90s to around 100. Thunderstorms are expected, though timing and coverage are extremely uncertain, so held with a broad 20-50% PoPs through every period in the long term. Details will become more apparent as we get closer. Severe thunderstorms will be possible as high dew points contributes to potentially substantial instability (alongside low to moderate deep layer shear). Previously most models had an upper-level trough swinging down crossing the Great Lakes by Wednesday, but there are now a few more solutions starting to slow this trough down, which would add another day of heat, humidity and thunderstorm chances. However, ensemble average favors lower temperatures and precipitation chances for Wednesday. && .AVIATION /18Z Thursday THROUGH Tuesday/... Most of northern Ohio has cleared out of the thicker lake effect cloud cover with VFR conditions this afternoon. There is still a pocket of MVFR ceilings due to lake effect clouds over far NEOH and NWPA impacting YNG and ERI this afternoon. We expect these areas to eventually break out of the MVFR ceilings and scattered out the clouds later this afternoon into the early evening hours. All areas will be VFR tonight into Friday morning. There could be a little light fog around ERI after 06z tonight and have this possibility mentioned in a TEMPO group for 5sm light fog or BR through about sunrise. Some mid level cloudiness may move into NWOH by Friday morning and there could be a couple isolated rain showers around TOL and FDY but think the overall chances are too low to mention in the TAF at this time for those locations. Winds continue to slowly decrease this afternoon out of the north and northwest 10 knots or less. Winds will be become lighter tonight under 5 knots. Most areas will either have light and variable winds or nearly calm conditions this evening into the overnight. A light southeast winds may return 5 knots or less over northwest and north central Ohio by Friday morning. A lake breeze will shift the winds from the north-northeast by midday or early afternoon for CLE and ERI about 8 knots or less. Outlook...Isolated showers/thunderstorms with non-VFR possible in NW Ohio Friday. Periodic rounds of showers and thunderstorms with non-VFR may be possible this Sunday through Tuesday. && .MARINE... Northwest winds are past their peak and should gradually diminish through the day today as high pressure gradually builds in from the west. As such, we should be able to gradually chip away at the small craft advisories and beach hazard statements, with all marine headlines gone by 20Z. High pressure lingers through Friday before departing to the east coast Friday night. Southwest flow develops by Sunday which is expected to last through midweek. There is a low chance that periods of 20 knots winds within this southwest flow, though uncertain when the best chance for this to occur. && .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 4 PM EDT this afternoon for LEZ146>149. && $$ SYNOPSIS...Garuckas NEAR TERM...Garuckas/Griffin SHORT TERM...Saunders LONG TERM...Saunders AVIATION...Griffin MARINE...Saunders