Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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919 FXUS63 KMQT 090848 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 448 AM EDT Thu May 9 2024 .KEY MESSAGES... - Clipper system brings chances for thunderstorms to the far western areas of Upper Michigan Friday afternoon and Friday evening. - Chances for thunderstorms return on Sunday for the west half of the Upper Peninsula. - Multiple passing low pressure systems will keep rain and thunder chances in the forecast next week, but uncertainty on timing and track remains. && .SHORT TERM /THROUGH TONIGHT/... Issued at 325 PM EDT Wed May 8 2024 Water vapor imagery and RAP analysis show a broad mid-level low centered over SD and troffing over se Canada back into the Great Lakes. Into the latter trof, a shortwave is dropping toward Lake Superior. Btwn the mid-level low and the eastern trof, a col is over ne MN/NW WI. In the wake of the shortwave that brought rain to the area last night, particularly the e half of Upper MI, it`s been a dry aftn so far, but daytime heating has led to cu/stratocu development inland from the stabilizing influence of Lake Superior. Recent radar imagery indicates that these clouds are now building enough depth for some sprinkles or a few -shra in eastern Gogebic County. Temps currently range from the 40s near Lake Superior to the mid 60s F in the interior closer to the MI/WI stateline. Approaching shortwave from the n and weak diurnal instability will support some -shra/sprinkles over portions of interior western Upper MI near the MI/WI stateline for the next several hrs. Not out of the question that a few sprinkles could develop over the eastern fcst area as well given the buildup of clouds in that area. A dry night will then follow with skies becoming partly cloudy. 850mb thermal trof is currently supporting considerable stratocu ne of Lake Superior. As this thermal trof advects sw, stratocu will also advance sw. Some of this cloudiness may appear in Upper MI around sunrise, but probably more so during Thu morning. Expect low temps tonight in the mid 30s to lwr 40s F. && .LONG TERM /TONIGHT THROUGH WEDNESDAY/... Issued at 447 AM EDT Thu May 9 2024 Starting tonight, a trough will be settling south while ever so brief ridging and sfc high pressure builds in over the UP from the northwest. While this trough settles south, some shortwave energy passing over the eastern UP may give some additional forcing for clouds. That said, q-vector divergence and dry model soundings indicate dry weather will persist under mostly clear skies are expected. With good radiational cooling, temps below normal are forecast with lows in the upper 20s to 30s, coolest in the interior west. Dry weather ends Friday afternoon as shortwave over the Manitoba/Ontario province line dives southeast into Upper MI and WI. Mixing ahead of the shortwave is expected to result in lower RHs into the upper 20s to 30s. That being said, there are no major fire weather concerns as highs for the day are expected in the mid 50s to mid 60s (cooler near the lakeshores), winds are expected to remain light below 15 mph, and precip is on the way. Some lake breezes are also likely late morning/early afternoon off both lakes which should help RHs recover some and result in some variable winds. PVA kicks off showers mainly after 2 PM EDT over the far west. As the cold front moves east over the UP then, showers move east with it. With mid level lapse rates ~7C/km and the 5/9 0z HREF mean MUCAPE around 100j/kg (individual models plotting up to 200-400j/kg) there is a slight chance for thunderstorms over the far western UP. That said, bulk shear is lacking (mainly below 25 kts) and the forcing mechanisms do not appear as strong later in the day. Severe weather is not expected. Chances for showers continue east across the UP Friday night as temps fall into the mid 30s to mid 40s. As the trough moves southeast toward New England on Saturday, additional shortwave energy advects over the UP suppling enough forcing for some slight chances of showers, mainly over the east on Saturday. Chances for showers and thunderstorms return again on Sunday as a sfc low over northern Ontario moves east, tracking a cold front across the UP. As we move into next week, there are discrepancies on precip timing and track and thus confidence diminishes. The GFS has a weak shortwave for later in the day Monday forcing some showers and potentially thunderstorms while the ECMWF stays dry with sfc ridging extending over the UP through Tuesday. The next best chances for showers and thunderstorms arrive mid to late next week when a shortwave riding east along the U.S./Canada border earlier in the week arrives at the Great Lakes. With current spread in the guidance, opted to leave NBM chance PoPs as is. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 150 PM EDT Wed May 8 2024 Lower level moisture is mixing out and is being lifted by building mixed layer. Advection of stabilizing marine layer off of Lake Superior will also work to limit any cu/stratocu development closer to the lake this aftn. For IWD/CMX, this stabilizing influence will allow VFR to prevail this aftn, and VFR will continue tonight. At SAW, expect stabilizing flow off of Lake Superior to result in MVFR cigs scattering out to VFR in the next hr or two. VFR will then continue at SAW tonight. Area of lower level moisture represented by the stratocu per vis satellite imagery well ne of Lake Superior will advect sw today and tonight. While some of this moisture will mix out this aftn, it should contribute to cu/stratocu/MVFR cigs developing at all terminals after sunrise on Thu. After a few hrs or so, cloud bases will lift to VFR, or the clouds will scatter out to VFR. && .MARINE... Issued at 447 AM EDT Thu May 9 2024 Northeast winds of 15-25 kts will diminish this morning, falling back below 20 kts across the lake as high pressure builds over the lake and stability increases. With this weak high pressure maintaining over the lake through tonight, winds likely will remain below 15 kts into the weekend as the stability remains. The exception to this is Friday night behind the cold front when the combination of cold air advection and downsloping off the northwestern shores of the lake may result in some gusts nearing 20 kts along the lakeshore areas. Some thunderstorms over the far western portions of the lake are also possible with the passing cold front. Winds increase to around 15-20 kts on Sunday as another cold front passes over the lake; some thunderstorms over the west half of the lake are possible with this cold front as well. Winds otherwise hold around 10-20 kts into the early parts of next week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Small Craft Advisory until 2 PM EDT /1 PM CDT/ this afternoon for LSZ240-241. Small Craft Advisory until 11 AM EDT this morning for LSZ242. Small Craft Advisory until 8 AM EDT this morning for LSZ243>245-250. Small Craft Advisory until noon EDT today for LSZ248-249. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...Jablonski AVIATION...Voss MARINE...Jablonski