####018006071#### FXUS66 KSEW 080335 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 835 PM PDT Tue May 7 2024 .UPDATE...We're in store for benign conditions here this evening. Lingering showers are on track to fizzle out as upper-level ridging builds in. Overnight lows are to fall into the mid 30s to lower 40s. The previous discussion remains below along with an updated marine/aviation section. .SYNOPSIS...An upper level trough will exit the region today and a ridge of high pressure aloft will begin to build into the area on Wednesday. The upper ridge will strengthen toward the end of the week as thermally induced low pressure near the surface expands northward into the area. Dry conditions will prevail along with the warmest temperatures of the year thus far on Friday and Saturday. A weak system passing to the north of the area will bring a minor cooling trend Sunday into Monday. && .SHORT TERM /TONIGHT THROUGH SATURDAY/...Scattered showers over much of the area will linger through the afternoon becoming limited to the Cascades the evening. There remains a 15-25% chance of isolated thunder over the Central and South Cascades this evening before showers completely taper out as upper level ridging begins to build into the area overnight. Morning clouds Wednesday morning will give way to sunshine with near normal high temperatures nosing well into the mid 60s. The the offshore upper level ridge will tip further over the region Thursday with thermally induced low pressure expanding northward along the Oregon coast. This will turn the low level flow northerly and offshore, which will help warming along the coastal areas a bit more than the interior. Hoquiam and Forks are expected to warm into the mid 70s (or higher) on Thursday afternoon. Interior areas will warm up as well...with lower to mid 70s common from the Seattle area southward. The upper ridge axis shifts onshore on Friday while the thermal trough remains more or less oriented along the coast. This will likely be the warmest day for the coast...with highs reaching the lower to mid 80s especially along the North Coast...which is daily record territory. In fact, there is a 90% chance of temperatures at or above 80 at Forks on Friday. Elsewhere, sunshine and warm temperatures with similar probabilities for temperatures above 80 across the interior lowlands from the Seattle Metro area southward , including much of the central Kitsap Peninsula. Model guidance continues to hint a a more progressive shift in the pattern Friday night with the ridge axis potentially broadening over much of the Western US and the thermal trough shifting inland. .LONG TERM /SATURDAY THROUGH TUESDAY/...The shift of the thermally induced surface trough onshore will help onshore flow and cooler temperatures for the Coastal areas with 15 to 20 degrees of cooling for Saturday. Warm temperatures will very likely linger for much of the interior, potentially as warm as Friday especially through the metro area. Onshore flow and a weakening in the ridge on Sunday as a system passes to the north will help temperatures dip into the 60s and 70s - still near or just above normal and dry. Dry and warm spring weather looks to linger into mid week. && .AVIATION...Upper-level ridging will continue to build across the Pacific Northwest through the rest of the week with northwesterly flow aloft turning northerly through the day Wednesday. Mostly VFR with a 25-30% chance for MVFR stratus to develop between 14 and 18Z at the Puget Sound terminals. Otherwise, a return to VFR after 18Z. Light north to north-northeast winds tonight, variable at times, then turning northerly 5 to 10 kt Wednesday by 18Z. KSEA...VFR this evening with light north-northeasterly surface flow around 5 kt, which should hold through much of the night before winds transitions more to the north-northwest 8 to 12 kt after 18Z. MVFR chances have decreased slightly, with a 25% chance through the 14-18Z window. Otherwise, VFR after 18Z. Davis && .MARINE...Winds have eased across the Strait this evening, thus ended the Small Craft Advisory for the West Entrance, with wind gusts still going strong through the central and east Strait. High pressure will build over the waters through Wednesday night. Thermally induced low pressure then will move up the coast on Thursday and shift inland Friday and east of the Cascades later on Saturday. Westerly winds will continue to remain breezy into Wednesday, particularly for the central Strait of Juan de Fuca, with Small Craft Advisory winds during this period, along with adjacent waters. Northerly winds will increase Wednesday afternoon into Wednesday evening, especially for the inner Coastal Waters, where brief SCA wind gusts may be possible. North winds then continue into the weekend. Seas of 10 feet will subside to 8 to 9 feet tonight and 6 to 7 feet on Wednesday. Davis/JD && .HYDROLOGY...The daily hydrology discussion has ended until the start of the next rainy season; it will only be updated as needed. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory until 2 AM PDT Thursday for Central U.S. Waters Strait Of Juan De Fuca. Small Craft Advisory until 8 AM PDT Wednesday for Admiralty Inlet-Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From Cape Flattery To James Island Out 10 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm-East Entrance U.S. Waters Strait Of Juan De Fuca. && $$ ####018007998#### FXUS63 KGRB 080338 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 1038 PM CDT Tue May 7 2024 Updated aviation portion for 06Z TAF issuance .KEY MESSAGES... - A few strong storms are possible through early this evening, mainly south of a line from Marshfield to Waupaca to Oshkosh. The primary hazards will be small hail and gusty winds. - Areas of dense marine fog are expected through late this evening along Lake Michigan to the south of Algoma. - Areas of frost are expected to develop over parts of central and north-central Wisconsin on Thursday night. - Active pattern to continue into early next week. && .DISCUSSION... Issued at 253 PM CDT Tue May 7 2024 Short Term...Tonight and Wednesday Arc of steady rain that swept through earlier driven by mid-level fgen has given way to scattered showers and a few thunderstorms into central WI. Thus far the strongest thunderstorms by far are over southern WI closer to warm front and on edge of MLCAPES up to 1000J/kg. An isolated strong storm remains possible 3-7p as warm front and instability attempt to shift northward. Easterly flow off Lake Michigan will slow the progress somewhat. SW/S areas generally south of a Marshfield to Waupaca to Oshkosh line will see greatest risk for small hail and gusty winds. Then, will have to see if another cluster of showers and storms currently developing ahead of occluded front over western WI can make it into western area later this evening. Likely these will outrun greater instability while working eastward, so they should be in a weakening state. Chances of showers and storms drop off after late evening. Fog will be an issue right along the Lake Michigan shore this evening then more areas could see patchy fog overnight with today's rain and nighttime low-level inversion setting up. Wednesday begins mainly dry though a few spot showers or sprinkles could still occur along the Upper Michigan border closer to departing H85 low and cyclonic flow to the west of it. Expect a mix of sun and clouds otherwise into early afternoon. Possible that a few showers develop mid to late afternoon either from pop-up showers or storms due to buildup of at least weak instability farther inland or due to weak H85 trough dropping in from the north during the afternoon as the Canadian has been showing for the last couple days. GFS on board now too, so there may be something to it. Soundings and instability progs would only support thunder over central WI though. Decent range in temps on Wednesday from highs only around 60 in the north, to readings well into the 70s over the southwest forecast area. Long Term...Wednesday Night Through Tuesday An active weather pattern to continue over northeast WI into early next week as a series of systems traverse the region. The first system to be a weakening upper low into an upper trough with precipitation chances Wednesday night into Thursday. Mean flow turns northwest into WI by late week with the passage of two shortwave troughs (Friday night and Sunday afternoon/night) bringing additional precipitation chances. Temperatures to generally be at or below normal through the weekend, then slightly above normal early next week. Wednesday night and Thursday... An elongated shortwave trough stretching from eastern Canada to the Midwest will swing through northeast WI Wednesday evening into Thursday morning. Instability looks minimal at best over the northern half of the state and stronger forcing to be focused to our south, thus have kept thunder out of the forecast. Anticipate shower chances to range from slight from Hwy 8 northward, to likely from Hwy 21 southward. Rainfall amounts over parts of central and east-central WI will range from one-tenth to one-third of an inch. Min temperatures Wednesday night to range from 35-40 degrees far north, middle to upper 40s south. High pressure is forecast to begin building south into the western Great Lakes by Thursday morning which should start to dry things out. Max temperatures Thursday to be in the middle 50s to lower 60s. Thursday night and Friday... This high pressure will move across the forecast area Thursday night, allowing for skies to clear as well as bring a cooler air mass to the region. Min temperatures across north-central WI could drop to around 30 degrees with lower to middle 30s for central and far northeast WI. This may bring frost headlines into play if winds can decouple which is looking more likely. Anyone with sensitive plants may want to take the appropriate precautions. By Friday, clouds will be on the increase as a sharp upper trough digs southeast across the Upper MS Valley. By the afternoon, enough lift from the left exit region of the upper jet, in concert with increasing Q-G/FGEN mid-level forcing, could bring a chance of showers into central WI. Max temperatures on Friday to mainly be in the lower to middle 60s. Friday night and Saturday... This upper trough sweeps southeast across the western Great Lakes Friday night with a chance of showers and a slight chance of thunderstorms. Even as this trough departs on Saturday, lingering cyclonic flow may keep shower chances in the forecast through at least the morning hours. Limited sunshine and north wind will keep max temperatures Saturday in the upper 50s to middle 60s. Saturday night and Sunday... After a brief lull in the precipitation Saturday night as a weak surface ridge slides across WI, a weaker upper trough is progged to move into the western Great Lakes Sunday afternoon. This trough will be accompanied by a cold front, thus another chance for showers across northeast WI. A minor uptick to temperatures aloft will bring max temperatures on Sunday into the lower 60s near Lake MI, lower to middle 60s north and middle 60s to around 70 degrees south. Sunday night and Monday... The chance for showers will linger into Sunday evening until the cold front clears the area. The rest of Sunday night should be dry under partly to mostly cloudy skies. A cool air mass is left behind over northeast WI on Monday with 8H temperatures of 0 to +4C. This cooler air and the passage of a mid-level shortwave could kick off a few showers Monday. If the showers stay away, max temperatures on Monday could reach the middle 60s lakeside, upper 60s to lower 70s inland. Monday night and Tuesday... Models diverge after Monday with the GFS bringing a push of warmer air toward WI with more rain chances versus the ECMWF which sends high pressure into WI. Have followed the blended guidance which does bring a chance of showers to all of northeast WI by Tuesday. Max temperatures on Tuesday to be in the middle 60s near Lake MI, upper 60s to middle 70s inland. && .AVIATION...for 06Z TAF Issuance Issued at 1038 PM CDT Tue May 7 2024 Although thunderstorms have ended across the region, showers continue at times as an upper level low tracks east of the region. This activity should end from west to east early overnight, leaving behind a mix of IFR/LIFR conditions across north- central/central Wisconsin and a mix of MVFR/VFR across east- central Wisconsin. In addition, showers are expected to continue at times across north-central Wisconsin through early Wednesday morning. Flight conditions will eventually improve to VFR everywhere on Wednesday as the low continues to track east. A low pressure systempassing to the south Wednesday evening could bring some showers to central and east-central Wisconsin; however, recent model trends keep this activity away from the TAF sites. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....JLA/Kallas AVIATION.......Kurimski