536 FXUS61 KCLE 061932 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 332 PM EDT Sun Oct 6 2024 .SYNOPSIS... Strong cold front continues to sweep east across the area through this evening. Canadian high pressure builds overhead behind the cold front Monday and will persist through the week. && .NEAR TERM /THROUGH MONDAY NIGHT/... Broad upper level trough will continue to drag a cold front eastward across Northern Ohio and Northwest Pennsylvania before exiting early this evening. Behind the front, lingering upper level energy sags south which will supply a brief window for lake effect clouds and rain showers before Canadian high pressure builds overhead. Already seeing much drier air upstream behind the front in Northern Indiana with dew points in the 30s and RH values between 15-25%. Expect for this dry air to work itself into Northwest Ohio this afternoon and evening. The combination of wind gusts between 25 and 35 MPH, low RH values, and dry vegetation has led to an elevated risk of fire spread through early this evening across Northwest Ohio. 10 hour fuels remain a bit too high for Red Flag criteria, so kept the Special Weather Statement in effect through this evening. At his point we are beginning to see a cu field develop along the I-71 corridor as the cold front surges eastward into an unstable environment. Sufficient daytime heating has allowed for MLCAPE values to rise into the 1000-1500 J/kg range with deep layer shear of 30-40 knots. Still anticipating for thunderstorms to initiate fairly quickly over the next few hours with initiation generally occurring along a line from Ashtabula to Canton and points east. Strong to severe thunderstorms with all hazards (damaging winds, large hail, and a few tornadoes) remain on the table in an unstable environment with plentiful deep layer shear. Primary hazards continue to be damaging wind gusts and large hail, but can't rule out rotating updrafts and/or few tornadoes given ample deep layer shear and low LCLs. As such, portions of Northwest Pennsylvania and eastern Ohio remain in a Slight Risk (Level 2/5) for severe weather this afternoon and early evening. The cold front quickly exits to the east tonight ushering in a much cooler airmass. Overnight lows tonight dip into the mid 40s inland with low 50s in place along the lakeshore. Upper trough and shortwave aloft dip south tonight into tomorrow which will allow for lake effect clouds and rain showers to develop downwind of Lake Erie. Northerly flow will keep cooler temperatures in place with highs on Monday ranging between the mid/upper 50s in Northwest Pennsylvania to the low to mid 60s across Northern Ohio. Canadian high pressure builds overhead through Monday which will lead to improving conditions but another chilly night with lows dipping into the lower 40s. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Low impact weather will continue through mid-week, along with traditionally cool Fall temperatures as deep mid/upper troughing persists across the Great Lakes and eastern Canada. The mid/upper longwave trough axis will be located across the Great Lakes Tuesday, gradually shifting into New England Wednesday and Wednesday night as the associated closed low drifts from northern Ontario to the Canadian Maritimes. This will allow a large area of cool Canadian high pressure at the surface to shift from the heart of the Midwest Tuesday to over the Great Lakes and Ohio Valley by late Wednesday and Wednesday night. This pattern all points to seasonably cool fall temperatures, with generally low to mid 60s for highs both Tuesday and Wednesday. Far NE Ohio and NW PA will stay in the upper 50s, while NW Ohio sees upper 60s. Lows will generally be in the 40s both nights, with upper 30s along the US 30 corridor and in interior NE Ohio and NW PA. Wednesday night has the better chance for 30s as the high builds in to set up better radiational cooling, so frost is possible in interior NE Ohio and NW PA. Before the high builds in, NW boundary layer flow across Lakes Huron and Erie combined with moderate to strong lake induced instability will generate some lake-effect rain showers Tuesday into Wednesday in far NE Ohio and NW PA. This entire window will likely see some showers, but late Tuesday and Wednesday morning will have the greatest coverage as a final shortwave drops through the mean mid/upper trough with 850 mb temps dropping to just below 0 C over the eastern basin of the lake and equilibrium levels rising to 15-16 thousand feet. This will yield extreme instability of 650-900 J/Kg, so have solid chance PoPs. Also added thunder given the instability. Shear at times seen in NAM BUFKIT forecast soundings and pretty dry air overall will limit the organization of this activity. && .LONG TERM /THURSDAY THROUGH SUNDAY/... The aforementioned large Canadian high will gradually settle from the Great Lakes and Ohio Valley Thursday to the Tennessee Valley Friday as a strong mid/upper shortwave trough drops through the Great Lakes and NE CONUS Saturday into Sunday. An associated deep surface low moving through northern Ontario will drag a strong cold front across the region Saturday night or Sunday which will bring the next potential for rain showers. Timing of the front is uncertain 7 days out, but at this point, limited moisture advection ahead of the front will limit QPF despite what looks to be strong synoptic forcing. This will unfortunately keep drought conditions status quo. Highs will remain cool in the low to mid 60s Thursday, with upper 50s continuing in far NE Ohio and NW PA and upper 60s in NW Ohio. Warm air advection ahead of the front will boost highs into the low to mid 70s Friday and possibly mid 70s to near 80 Saturday. Temperatures should cool into the upper 60s to low 70s Sunday. && .AVIATION /18Z Sunday THROUGH Friday/... Cold front is continuing to move east across terminals this afternoon with elevated wind speeds and gusts impacting every TAF site. Ahead of the front, southerly winds 15-18 knots with gusts of 20-25 knots with turn westerly behind the front this afternoon and evening. As the front approaches eastern terminals this afternoon, expect for showers and thunderstorms to develop along a line extending from Ashtabula to Canton and points east between 19-21Z. Introduced TEMPO groups for TSRA impacts at CAK/YNG/ERI from 20Z/Sun-00Z/Mon. Strong to severe thunderstorms remain possible with thunderstorms capable of producing IFR vis, gusty winds, and hail. After the front exits to the east after 00Z tonight winds turn northwesterly while decreasing to 8-12 knots. Northerly to northwesterly winds across a relatively warm lake will allow for lake effect showers with low VFR to MVFR ceilings to enter downwind of Lake Erie early Monday morning. Outlook...Non-VFR ceilings possible in lake effect clouds and light showers across northeast OH and northwest PA Monday. && .MARINE... W to SW winds of 15-25 knots across Lake Erie will continue until a strong cold front crosses the lake this evening. This will veer winds to NW at 20-30 knots early tonight before NW winds decrease to 15-25 knots. NW winds will gradually decrease to 10-15 knots Monday. These winds will build 4 to 8 foot waves late this evening and tonight, especially in the central and eastern basins, so Small Craft Advisories will continue on the entire lake through 20Z Monday. NW winds will then average 10-20 knots through Wednesday before turning light and variable by late Thursday, then SW at 10-20 knots Friday. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...Small Craft Advisory until 4 AM EDT Monday for LEZ142-143. Small Craft Advisory until 4 PM EDT Monday for LEZ144>149. && $$ SYNOPSIS...Iverson NEAR TERM...Iverson SHORT TERM...Garuckas LONG TERM...Garuckas AVIATION...Iverson MARINE...Garuckas