Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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057 FXUS63 KMQT 131145 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 745 AM EDT Sat Jul 13 2024 .KEY MESSAGES... - Seasonably warm Saturday through Monday with periods of showers and thunderstorms, some of which could be strong to severe. - Cooling and drying trend into the midweek portion of next week with the arrival of high pressure. && .SHORT TERM /TODAY/... Issued at 446 AM EDT Sat Jul 13 2024 Water vapor imagery/surface analysis early this morning indicate subsidence over Upper Michigan due to upper level ridging. This equates to mostly clear skies and a warm morning with temperatures holding in the 60s across the forecast area per current ground-based obs. Limited cloud cover and WAA in the southerly surface flow will push today`s highs well into the 80s with downsloping areas near Lake Superior approaching the 90 degree mark. In addition to the heat, focus will be on a shortwave trough approaching from the west this afternoon. CAMs/HRRR solutions, though, keep any convective development confined to the far western portions of the UP mid/late afternoon with the shortwave being counteracted by high pressure over the remainder of the forecast area until the evening hours. && .LONG TERM /TONIGHT THROUGH FRIDAY/... Issued at 531 AM EDT Sat Jul 13 2024 The extended forecast starts off active with two systems late this weekend and early next week as shortwaves ride the zonal flow aloft. Meanwhile, low level southwesterly flow will support WAA and moisture advection, priming the atmosphere for strong to possibly severe storms. High pressure then returns mid next week, resulting in a drier and quieter weather period. Starting tonight, a shortwave positioned over the MN Arrowhead/Western end of Lake Superior progresses east across the region. The thunderstorms possible tonight will depend on ongoing upstream convection and potential redevelopment later in the day, so confidence in timing and location is still low. A handful of the CAMs indicate convection currently over SW Manitoba will continue moving east with the shortwave, developing into an MCS somewhere over the northern half of MN late this evening. The 6Z HRRR leans into the redevelopment solution and stays mainly to the south of our CWA. While the NAM/FV3 are the solutions are the more of a worst case situation, taking the system southeast right across the entire CWA, the NSSL hardly yields any thunderstorms anywhere in our area. The likely solution is for any MCS to track southeast, mainly through WI. Given the uncertainty, the best chances right now for thunderstorms are in the west, mainly near the WI/MI state line between 3Z and 9Z Sunday. Main threats will be winds given the inverted-v soundings and convective mode. That said, bulk shear around 25-30 kts, mid level lapse rates around 7C/km, and MUCAPE ~1000-2000 J/kg would support hail as well. Otherwise, expect mild lows in then mid 60s. Any lingering convection Sunday morning moves out leaving a mainly dry start to the day. Given the elevated dew points nearing 70 in the east and warm temps in the 80s (possibly some low 90s south central), instability returns; the 7/13 0Z HREF mean MUCAPE builds up to 1000-2000 J/kg. The shear profile will be supportive of any thunderstorms that do develop with around 30 kts of bulk shear. Forcing looks to be primarily driven by any lake breeze convergence, which leaves low confidence in thunderstorms again. The UP then returns dry Sunday night with lows in the upper 50s to mid 60s, cooler in the interior. Monday into Monday night brings another round of showers and thunderstorms as another shortwave tracks across the region and an associated sfc low follows east over Lake Superior/northern Ontario. Bulk shear sees a significant increase from previous convection with up to 1000 J/kg of MUCAPE, so some strong to severe storms are possible ahead of the cold front. Although a mid level closed low will be shifting east through northern Ontario and Quebec Tuesday and Wednesday, sending a shortwave over the area during that period, dry weather returns as high pressure begins building in from the northwest. How long this dry period will last will depend on when the next shortwave progresses southeast through the Upper Great Lakes as the mid level ridge over the western CONUS slowly shifts east. Slight chances hold off until late next weekend. Otherwise, a cooler period is expected accompanying the high pressure and northwest flow. && .AVIATION /12Z TAFS THROUGH 12Z SUNDAY/... Issued at 745 AM EDT Sat Jul 13 2024 VFR conditions will hold steady through the TAF period despite the threat for showers and thunderstorms later today and into tonight. For now, confidence is only high enough to carry VCTS mention at IWD tonight, but thunder could be added to SAW with future TAF updates/issuances. In addition, there will be a LLWS threat at SAW tonight with an uptick in a low level jet. && .MARINE... Issued at 547 AM EDT Sat Jul 13 2024 Southerly winds remain below 20 kts today as the pressure gradient stays light. South winds increase tonight over the east to around 20 kts with a 15-30% chance for gusts reaching 25 kts tonight ahead of the next disturbance. Some strong to severe storms are possible tonight, especially across western Lake Superior. The main threats are damaging winds, but large hail is also possible. Another round of storms is expected Monday into Monday night as a low pressure system moves through the area. Patchy dense fog is also a possibility in the wake of any precipitation. Following the Monday/Monday night low presusure`s cold front, west winds increase to around 20 kts across much of the lake Monday night and Tuesday. As high pressure begins to build in mid next week, winds look to fall back below 20 kts, remaining light through the remainder of the forecast period. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...TDUD LONG TERM...Jablonski AVIATION...TDUD MARINE...Jablonski