Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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073 FXUS63 KMQT 161743 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 143 PM EDT Sun Jun 16 2024 .KEY MESSAGES... - Possible strong to severe thunderstorms this evening and tonight. Large hail, damaging winds, frequent lightning, and heavy downpours will be possible. - Possible strong to severe thunderstorms Monday and possibly Tuesday night/Wednesday. - Very warm early next week, with frequent chances for showers and thunderstorms throughout. && .SHORT TERM /THROUGH TONIGHT/... Issued at 142 PM EDT Sun Jun 16 2024 Rain showers continue to lift through the forecast area atop a very moist surface layer. As of publishing this AFD, rain showers were spread across the eastern and central UP with dewpoints in the mid 50s to low 60s across the region. Destabilization ahead of mid-level ridging building into the west may support additional shower development, or some thunderstorms in this afternoon across the east half before they exit into Ontario. Severe weather is not expected in this wave. The atmosphere will further destabilize ahead of a cold front/low pressing eastward through Minnesota this afternoon. Guidance continues to suggest this will result in shower and thunderstorm development with quick upscale growth into an MCS, which will progress east-southeast into Wisconsin and Upper Michigan this evening. The strong destabilization in the pre-frontal space stretching from Wisconsin into the U.P. is characterized by 2000- 3000 j/kg of elevated CAPE. While the region where this will develop is expecting much stronger deep layer shear, guidance over Lake Superior generally suggests around 30-40kts of 0-6km bulk shear oriented off the boundary, suggesting the linear complex may survive the transit and move into Upper Michigan. With DCAPE 500-1000j/kg and increasing mid-level lapse rates to around 8C/km, strong to severe thunderstorms will be possible if so. Main hazards will be large hail up to 1 inch in diameter, strong or damaging winds upwards of 60mph, frequent lightning, and heavy rain upwards of 1+ inches this evening. Primary risk areas will be across the west/central, but some guidance packages, namely the RAP, ARW and FV3, suggests the thunderstorms could hold together as they move into the east half around midnight. A warm and muggy night is projected after the convection ends. As temps begin to cool, patchy dense fog may develop overnight. Overnight lows and dewpoints are likely to remain in low to mid 60s for most of the forecast area. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 503 AM EDT Sun Jun 16 2024 Active weather continues through the extended period as troughing deepens over the western U.S. and ridging amplifies over the Eastern Seaboard. This pattern will cycle very warm and moist air over us early in the work week, in addition to many chances for showers and thunderstorms throughout. With strong shearing and abundant CAPE in the atmosphere, some severe weather could occur early this week. More details follow below. As the Great Lakes region remains situated in between the high- amplitude ridge and digging western trough Monday through Tuesday, southerly flow continues to pump in a warm, moist airmass with dewpoints well into the 60s and even above 70F Monday and Tuesday. Monday will start off with rain chances as a subtle shortwave tracks through the area. Convection will be most likely across the western UP, closer in proximity to the weak wave as well as the frontal boundary that will be stalled out just to our west. Early on, shear is rather limited, and though we will be plenty unstable given such high dewpoints, lower to midlevel capping is apparent in soundings. An early start to our convection may also limit destabilization. That said, will not rule out some hail in morning/early afternoon convection if we can realize the full potential of the ~1000j/kg of CAPE analyzed over the area. Showers and storms will also have the impact of limiting temperatures over the western UP to the 70s, while the eastern half of the UP stands a better chance of reaching the lower to mid 80s. Will note that guidance is really struggling to come into agreement on the spatial extent of PoPs for the daytime, with some models showing a far greater eastward expansion than others. Most of the UP should dry out Monday evening as the shortwave exits northward and the eastern ridge begins to build NW-ward again. That said, the western UP is not out of the woods as theta-e advection increases overnight on the nose of an impressive 40-50kt LLJ that will be directed into the Upper Midwest. Quite impressive CAPE in excess of 1000j/kg and bulk shear in excess of 40kts indicate a potential for strong elevated convection overnight, with the main risks being hail and gusty winds. Will also note a potential for heavy rain, given PWATS in excess of 1.5in and a potential for training storms ahead of a very slowly-moving front. Very important caveat: the front remains well off to our west, and guidance continues to just graze the western UP and western Lake Superior with PoPs. Dry weather is looking likely across most of the UP through Tuesday while the frontal boundary stalled out over MN finally begins to slowly creep eastward. Under sunny skies, temperatures climb even higher than on Monday, possibly peaking in the 90s in many locations during; it`s not out of the question that we could set a heat record or two come Tuesday as ensemble guidance shows temperatures around the 99th percentile of modeled climatology. If there is one upside, southerly winds will be fairly elevated given the tight pressure gradient over the area; expect gusts around 20-25mph for much of the UP. The aforementioned frontal boundary crawls over the Great Lakes Tuesday night through Wednesday, and looks to stall out just to our south into Thursday. Expect additional rain shower and thunderstorm chances as this moves through, with temperatures cooling close to normal. As more zonal flow moves over us with weak high pressure setting up shop over northern Ontario and the Northern Plains, expect to see the rain and thunderstorm chances continue as shortwaves continue to ride the upper-level flow across our area. A more trough-ey pattern sets up next weekend, and though details on track, timing, and strength of any particular features remain uncertain, this will in general keep rain chances in through the end of the forecast period. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 142 PM EDT Sun Jun 16 2024 Ample low level moisture and rain showers over the region should improve this afternoon as weak, mid-level ridging builds west to east across Upper Michigan. This should support an end to the rain and ceilings lifting to VFR this afternoon/early evening. Upstream thunderstorm development is expected in Minnesota this afternoon. These thunderstorms will press east-southeast through Upper Michigan this evening. These are most likely to impact KIWD and KCMX, but KSAW may still seem some thunderstorms late this evening. These storms could be capable of large hail, damaging winds, heavy downpours, and frequent lightning. After the thunderstorm activity ends, guidance is keen on fog/mist developing, which may reduce visibilities at each terminal to MVFR or potentially IFR. && .MARINE... Issued at 503 AM EDT Sun Jun 16 2024 Winds generally out of the southeast this morning continue to gust up to 20-25kts across the eastern and north-central portions of the lake, but gusts increase to 25-30kts across the eastern half of the lake this afternoon while winds turn more southerly. In addition, some southerly gusts up to 30 knots will be possible along the south Lake Superior nearshores throughout the day, with a few gale force gusts up to 35 knots being possible near Grand Marais and Munising during the afternoon hours. Winds weaken to 20 knots or less by late Sunday afternoon/evening and remain that way until Tuesday, when some southerly winds of 20 to 25 knots could be seen across much of the lake. Light winds of 20 knots or less returns Tuesday night and could remain through the rest of the week. Several rounds of showers and storms are expected today through Tuesday with a frontal boundary stalled out over MN eventually moving through the area by midweek. Some severe weather is possible over the lake, particularly over the west, Monday through Monday night; the primary severe threat is hail, followed by winds. In addition, while significant wave heights look to be generally 4 feet or less over the next several days, we could see wave heights get up to 4 to 6 feet over the eastern half Sunday given the stronger southeast to southerly winds. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Beach Hazards Statement until 10 PM EDT this evening for MIZ014. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JTP LONG TERM...LC AVIATION...JTP MARINE...LC