Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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430 FXUS63 KMQT 061127 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 727 AM EDT Sat Jul 6 2024 .KEY MESSAGES... -Slight chance (~20%) for late afternoon showers and thunderstorms across interior western Upper MI today. -Sunday through Wednesday, daily chances of showers and thunderstorms, highest chances in the afternoons. Could see a couple of strong storms Sunday and maybe Monday (higher uncertainty). -Dry period begins Thursday, could be dry into next weekend. && .SHORT TERM /THROUGH THIS AFTERNOON/... Issued at 321 AM EDT Sat Jul 6 2024 Water vapor imagery and RAP analysis show that the shortwave that brought shra to the area yesterday is exiting eastern Upper MI. A few -shra associated with that feature are still lingering over the eastern fcst area. The rainfall that occurred over Lake Superior has generated fog/stratus, and the fog/stratus has been moving onshore across the e half of the fcst area, roughly e of Marquette to Menominee line. To the w, skies are clear, and with winds light to calm, patchy fog is developing. Current temps generally range through the 50s F, but some mid and upper 40s F are noted at traditional interior cold spots over the w. Patchy fog over the w will dissipate within an hr or so after sunrise. To the e, fog/stratus will also dissipate this morning after sunrise from s to n. However, GOES night fog imagery shows quite a bit of fog/stratus over eastern Lake Superior. With meso high developing over eastern Lake Superior today, resulting in onshore winds, areas very close to the lake may see fog/stratus linger well into the aftn. Attention then turns to possible aftn convection over western Upper MI. Models show MLCAPE building to anywhere from a few hundred j/kg to up to around 1000j/kg this aftn. Although weak mid-level shortwave ridging moving over the area is a negative for convection, nearly all of the 00z models show isolated convection developing this aftn, similar to previous runs. Have thus opted for slight chc pops (15-24%) over interior w half of Upper MI, roughly s of a line from around Ironwood to Champion, Gwinn to Menominee. High temps today will range thru the 70s to around 80, except 60s F along Lake Superior, especially from around Marquette eastward. If fog and stratus linger thru the day close to the lake, lakeside locations in Alger/Luce counties will only top out at about 60F. && .LONG TERM /TONIGHT THROUGH FRIDAY/... Issued at 325 AM EDT Sat Jul 6 2024 Ridging building over the West Coast of the U.S. early next week will allow weak shortwaves to cycle over us, bringing daily chances for rain showers and thunderstorms across our area for the afternoon to evening hours out to the middle of next week; we could see a couple strong sub-severe storms Sunday and maybe even Monday. However, moving into the second half of next week, as the high pressure ridge over the West Coast moves eastward into the Central and Eastern U.S., drier weather looks to move over us to end next week. Additional details follow below. Some isolated diurnal rain showers and thunderstorms end over the interior west this evening as the sun sets. While MUCAPEs are projected to be between 1000 to 1500 J/kg early this evening, with there being very little shearing in the atmosphere due to the departing weak sfc ridge overhead, only garden-variety pop-up showers and storms are expected. Moving into tonight, we could see some patchy fog develop across the interior areas as we look to be mostly clear until late tonight; expect the fog to burn away a couple of hours after dawn. However, as we approach dawn late tonight, expect clouds to roll in from our west as another shortwave low moving in from the Northern Plains encroaches our area. While this 1010mb low is nothing to write home about, it does look to bring in more showers and thunderstorms across the western half of the U.P. by late Sunday morning. CAMs show rain shower and thunderstorm coverage to be fairly scattered throughout the western half of the CWA Sunday, with convection dying out as it tries to enter into the eastern half due to subsidence remaining from the departing weak high pressure ridge. With over 1000 J/kg to work with in the atmosphere by Sunday afternoon and 0-6 km bulk shear being around 30 knots, we could see a couple strong thunderstorms bring sub-severe winds and hail across the western half late in the day. However, as we move into the evening to overnight hours Sunday night, expect the convection to weaken after the sunset, with showers and thunderstorms becoming isolated by the overnight hours. A second weak sfc shortwave lifting from the Central Plains fires up more rain showers and thunderstorms over our area Monday. Expect to see similar conditions to Sunday, with even a couple strong storms being possible late in the day (although there is greater uncertainty in the CAPE and bulk shear). However, once we get into the late night hours Monday night, expect the convection to die-out as the forcing weakens. More of the same is expected Tuesday and Wednesday as additional, weaker sfc shortwaves rotate through our area; expect the convection to be dependent on the diurnal heating through the daytime hours in order to fire during the afternoon and early evening hours across the U.P. before the convection dies out by the late night hours. As this occurs, expect the temperatures to generally be in the 70s, with a slight increase occurring between Tuesday and Wednesday. This increasing temperature trend continues into the last half of next week as the high pressure ridging that initially was building over the Western U.S. travels over the Central and Eastern U.S. by the latter half of the extended period. This high pressure ridging is expected to keep us dry from Thursday into next weekend. && .AVIATION /12Z TAFS THROUGH 12Z SUNDAY/... Issued at 727 AM EDT Sat Jul 6 2024 Expect VFR and winds mostly under 10kt to prevail at IWD/CMX/SAW thru this fcst period. A few shra/possibly a tsra may develop across western Upper MI late aftn/early evening. Only a VCSH mention was included in fcst at IWD given the low confidence in occurrence. && .MARINE... Issued at 325 AM EDT Sat Jul 6 2024 Light winds of 20 knots or less continue this weekend through next week as weak shortwaves bring showers and storms along mainly the Lake Superior nearshores early this week before high pressure ridging brings dry and calm conditions over the lake late next week; while we may see a strong storm or two along the southern nearshores for wind and hail Sunday and maybe Monday (higher uncertainty), little, if any storms are expected over the open waters due to the subsidence caused by the Lakes. In addition, we could be seeing some patchy fog over the lake early this morning through today, mainly over the north central and eastern portions as weak sfc high pressure ridging moves through. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...TAP AVIATION...Rolfson MARINE...TAP