####018005949#### FXUS62 KILM 071337 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 937 AM EDT Tue May 7 2024 .SYNOPSIS... The area will remain between an inland trough and Atlantic high pressure into Thursday with unseasonably warm and humid conditions expected. Mostly limited showers and storms expected through Wednesday until a cold front moves through late in the work week bringing a better chance of rain and even some stronger storms. High pressure will then follow bringing drier and cooler conditions into early next week. && .UPDATE... Made some forecast changes for today to account for this rain moving through this AM. Expect this area of rain to diminish and push offshore along with the associated upper shortwave trough with mostly isolated to widely scattered showers and storms this afternoon, mainly along mesoscale boundaries due to the sea breeze, differential heating and convective outflows. && .NEAR TERM /THROUGH TONIGHT/... Ongoing scattered showers with isolated tstorms will be traversing roughly the northern 1/2 of the ILM CWA this morning. This in response to the mid-level s/w trof pushing across. Will includes POPs in the low to mid chance categories specifically for this pcpn. Otherwise, the s/w trof lifts E to NE of the FA by midday taking the convection threat with it. Meanwhile, with highs in the mid to upper 80s today, lower 80s at the beaches, expect a sea breeze to develop and push not too far inland as flow aloft will become W to NW. Have indicated a low chance for convection along this sea breeze. Upper ridging to dominate later today thru tonight with associated subsidence keeping convection at bay tonight. Sfc pressure gradient should tighten-some this aftn and remain thru tonight, keeping winds active across the FA which should be enough to keep fog potential to a minimum tonight. Lows tonight to remain closer to summer-like with upper 60s to lower 70s commonplace. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... The heat wave peaks on Wednesday with all places away from the immediate coast topping 90. The mid level ridge axis will be just offshore but it will still act to suppress all but isolated convection. There will be quite a bit of instability but with little to no forcing and fairly high LFC's (approaching 5kft) once again convective coverage should be minimal. The pattern starts to change on Thursday as a trough digs into the Great Lakes pushing a cold front in our direction. This will lead to a mainly late day increase in shower and storm coverage as well as possibly their intensity. && .LONG TERM /FRIDAY THROUGH MONDAY/... One last day of showers and storms on Friday before front moves through and dry air arrives. Guidance is trending a bit stronger with the mid level wave driving the front possibly offering a severe weather threat. The pattern shift is complete by Saturday with the main upper trough in the East, allowing much cooler and drier air to spill into the area. Expect a weekend with seasonable highs in the mid to upper 70s and lows in the mid 50s...much cooler than the mid week period but actually quite close to normal. A secondary cool front may push through on Monday. Any guidance showing precip with its arrival looks highly suspect. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... Mainly VFR thru the pre-dawn hrs, except inland terminals may see periodic MVFR from convection associated with a mid-level s/w trof passage thru midday. Included VCSH/VCTS unless pcpn looks imminent and requires prevailing conditions. This mid- level disturbance exits the area by early this aftn, leaving subsidence aloft in its wake. Have indicated convection along the sea breeze across the coastal terminals later this morning thru the aftn. Winds become WSW to SW 10 kt this morning and should increase 10-15 kt during the aftn/evening then only slowly diminish to 5 to 9 kt during the overnight. Extended Outlook...Looking at VFR dominating Wed into early Thu with limited/isolated convection. Threat of more widespread strong convection and periodic flight restrictions later Thu into early Fri ahead of a CFP. Clearing later Fri with VFR dominating thru Sat with high pressure prevailing. && .MARINE... Through Tonight...Sfc high centered offshore from the SE States Coast, will get slide slightly further E and S this period. At the same time, sfc trof across the central Carolinas becomes better established while frontal systems remain across the Mid- Atlantic States. This will result in a dynamic sfc pressure pattern conducive of SW to WSW wind directions. A tightening sfc pg will also be active resulting in 10-15 kt speeds increasing to around 15 kt today, with a 15 to 20 kt range to occur tonight. Seas generally in a 2 to 4 ft range with a few 5 footers. SSE-SSW wind waves at 5 second periods to dominate with an underlying small 10+ second period Easterly swell. Wednesday through Saturday Night...Southwesterly flow typical of the warm season in place early in the period as high pressure sits off the coast. The persistence of the fetch will add swell energy to the wind waves and by Thursday we may attain SCA criteria. Cold front moves through later Friday leading to veering winds that will also abate in speed. The swell will persist but also lessen. Wind gets all the way around to the north on Saturday before backing kicks in as another weak boundary approaches from the NW. && .ILM WATCHES/WARNINGS/ADVISORIES... NC...None. SC...None. MARINE...None. && $$ SYNOPSIS...ILM UPDATE...RJB NEAR TERM...DCH SHORT TERM...MBB LONG TERM...MBB AVIATION...DCH MARINE...DCH/MBB ####018010694#### FXUS61 KCLE 071338 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 938 AM EDT Tue May 7 2024 .SYNOPSIS... A frontal system moves through the region today and tonight. Brief high pressure Wednesday followed by another low pressure system Wednesday night into Thursday. && .NEAR TERM /THROUGH WEDNESDAY/... 930 AM EDT Update... Line of showers and thunderstorms over Illinois will continue to track east and weaken as it moves into at least the western third of the CWA by mid-afternoon. This line of convection will not be the main show for severe weather; the greatest area of concern will arrive with better forcing/dynamics this evening. This initial round of convection will do one of two things: provide a boundary for enhanced lift/intensification or provide convective debris that will require some recovery. Regardless, the environment will be very dynamic so severe weather will still be possible given the impressive wind shear. No changes needed with this update. Previous Discussion... Stationary boundary that is stalled over the Ohio Valley will begin its push back northward in response to an upper level closed low slowly ejecting from the intermountain west into the northern plains region. This upper low and the associated surface system will be occluding, but that will not completely stifle the eastward progress of the frontal system. This synoptic scale regime sets the stage for a potential severe weather threat for much of the forecast area today into early tonight. A couple of things will need to happen first, however. First there needs to be a push of low level moisture into the region as the column RH is on the lower side as we start out. This moisture flux will occur once the low level flow becomes southerly and increases, after 16Z today. Will also see a pronounced increase in the low level flow into western Ohio after 18Z spreading eastward, just a few hours later. One thing to watch for with the warm front is the northward extent that it can track, possibly held up by an onshore ENE wind from the position of a weak high pressure system over eastern Lake Ontario and upstate New York. This could be a tricky boundary. For one, it is a place for surface convergence, but the immediate near surface air over the lake is more stable. That said, elevated convection could still fire with some backing of the surface wind, and in the near saturated inversion over the lake, it could lower the LCLs in that area. Otherwise, expect destabilization across the area to occur aided by heating today, setting up vertical profiles in the afternoon for the western half of the CWA that are characteristic of high CAPE above the boundary layer, some drying above 600mb or so, a 75mb thick inverted V boundary layer, increasing low/mid level flows, and around 50-80 degrees of veering of the winds with height through the mid levels. In the end, a pretty good severe risk today into early tonight given all of these factors coming into play. Current expansive line of convection that is moving into the Mississippi Valley extending from Minnesota back southward through Missouri and then southwestward into Oklahoma will push into the CWA around 18Z or so. This should be just prior to the aforementioned low level moisture influx and shear increases, and expect this to decay as it moves eastward without much low/mid level support yet. The better threat comes from the next complex forming in its wake. Will need to watch to see if the atmosphere can recover, which it should do so from a dynamic standpoint, but always need to be wary of lingering convective debris. Cold front moves through west to east 03-09Z Wednesday with high pressure influences from the south moving in for tomorrow, and a dry forecast largely after 10Z. Temperatures mainly in the 70s both today and Wednesday, with perhaps a few low 80s over the southern zones Wednesday. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... Surface troughing is expected to reside over/near our CWA Wednesday night as a trough aloft approaches from the north-central U.S. and Upper Great Lakes. The attendant surface low should advance E'ward from near central IL to near the border of central IN/OH. Most of our area should reside in the cold sector, but the west-to-east- oriented front preceding the surface low should remain nearly- stationary across central OH, south of the U.S. Route 30 corridor. Convergence/associated moist ascent along the surface front should release weak boundary layer instability and moist isentropic ascent along the upper-reaches of the front should release weak elevated instability, leading to periods of scattered rain showers. Isolated general thunderstorms are possible, but despite the expectation of moderate deep layer bulk shear, the concern for severe thunderstorms is continuing to decrease given a relative dearth of MUCAPE forecast in/near our CWA. Overnight lows should reach the 50's to lower 60's around daybreak Thursday. The warmest lows are expected south of the surface front. The aforementioned trough aloft and embedded shortwave disturbances are expected to shift slowly from the western Great Lakes and vicinity to the eastern Great Lakes and Upper OH Valley on Thursday through Friday. Simultaneously, the attendant surface low is expected to continue to move generally E'ward and then ENE'ward along the preceding surface front (i.e the low should advance from near the border of central IN/OH around daybreak Thursday morning to near the Gulf of Maine by nightfall Friday evening. In the wake of the low, a much colder air mass is expected to overspread our CWA from the north and west, and a surface trough will linger over/near the eastern Great Lakes and stem from expansion of relatively-warm lake-modified air as the unusually-cold air mass for May 9th-10th advances across the lakes. Additional periods of scattered rain showers and isolated thunderstorms remain possible on Thursday through Friday due in part to the following: Moist isentropic ascent releasing weak elevated instability ahead of shortwave trough axes, self-destructive sunshine during the afternoon through early evening hours of both days, and the potential for lake-enhanced precip over and generally south or southeast of Lake Erie Thursday night into Friday morning amidst weak lake-induced instability over ~55F Lake Erie, a sufficiently-cold/moist low/mid-level atmospheric column, and the seeder-feeder process. A net low-level CAA regime should contribute to daytime highs reaching mainly the upper 50's to upper 60's on Thursday and the mid 50's to lower 60's on Friday after morning lows in the mid 40's to lower 50's. Odds favor fair weather Friday night as the aforementioned trough at the surface and aloft exits E'ward, a narrow ridge at the surface and aloft builds E'ward, and stabilizing subsidence accompanies the ridge. Overnight lows should reach 40F to 50F around daybreak Saturday as the unusually-cold air mass remains entrenched across our CWA. && .LONG TERM /SATURDAY THROUGH MONDAY/... Behind the above-mentioned ridge, cyclonic W'erly to NW'erly flow aloft and embedded shortwave disturbances are expected to become established over the eastern Great Lakes and Upper OH Valley this weekend through Monday, which will allow net surface troughing to impact our CWA and vicinity. Periodic showers/thunderstorms, isolated to scattered in coverage, are expected, especially during the afternoon and early evening hours given the typical diurnal cycle in boundary layer temperatures and instability is forecast. Afternoon highs should reach the 60's this weekend. Monday's afternoon highs should reach the mid 60's to lower 70's, when a warmer low-level air mass should overspread our CWA from the southwest, ahead of a stronger shortwave disturbance. Overnight lows should reach the 40's to lower 50's around daybreak Sunday and Monday mornings. && .AVIATION /12Z Tuesday THROUGH Saturday/... Already lifting the MVFR ceilings back to VFR thresholds above 3kft and expect this to continue through the early morning hours. Winds become southerly this afternoon 10-15kts with gusts 15-20kts in the wake of a warm front moving northward through the area and ahead of a cold front slated to come through 03-09Z Wednesday. Showers and thunderstorms expected this afternoon into early tonight. TEMPOs used to to time line of convection expected to form and move through the area. Gusty winds should be expected in any storms, and hail and isolated tornadoes cannot be ruled out. Outlook...Non-VFR likely with periodic showers and thunderstorms through Saturday. && .MARINE... Winds around 5 to 15 knots and waves of 3 feet or less are expected through Wednesday night. Winds trend NE'erly to E'erly today as a ridge exits slowly NE'ward and a warm front approaches Lake Erie from the southwest. NE'erly to SE'erly winds veer to SW'erly tonight as the warm front sweeps NE'ward across Lake Erie. Winds attempt to veer from SW'erly to W'erly on Wednesday as a cold front sweeps E'ward across the lake. Variable winds Wednesday evening become NE'erly to E'erly overnight as a ridge builds from northern ON and vicinity. NE'erly to E'erly winds around 10 to 20 knots back gradually to NW'erly on Thursday through Friday as a frontal low moves generally ENE'ward from near the border of central IN/OH to near the Gulf of Maine and extends a trough over the eastern Great Lakes. Waves of 1 to 3 feet with occasional 4 footers are expected and a Small Craft Advisory may be needed, especially Thursday night into Friday. A narrow ridge should build E'ward across Lake Erie Friday night and cause NW'erly winds to ease to 5 to 15 knots and back to SW'erly. Waves are forecast to subside to 3 feet or less. SW'erly winds around 5 to 15 knots and waves of 3 feet or less should persist on Saturday as a trough begins to overspread Lake Erie from the western Great Lakes. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. NY...None. MARINE...None. && $$ SYNOPSIS...26 NEAR TERM...Maines/26 SHORT TERM...Jaszka LONG TERM...Jaszka AVIATION...26 MARINE...Jaszka