Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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542 FXUS63 KMQT 121627 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 1227 PM EDT Fri Jul 12 2024 .KEY MESSAGES... - ~20% chance of isolated diurnally driven showers/thunderstorms this afternoon. - Hot and muggy conditions this weekend with the potential for a few strong to severe thunderstorms Saturday through Monday. - Cooling and drying trend into the midweek portion of next week with the arrival of high pressure. && .SHORT TERM /THROUGH TONIGHT/... Issued at 1227 PM EDT Fri Jul 12 2024 Early afternoon water vapor imagery shows a compact cutoff low over northern lower MI shifting east with shortwave ridging building in over the UP. Diurnal cu are firing up over central/western portions where lower-level dewpoints are a bit higher in the mid to upper 60s. Despite the synoptic-scale absence of forcing, as well as a low/mid-level cap evident on forecast soundings and SPC mesoanalysis, a few cams do depict isolated showers/storms this afternoon. Do not feel too bullish about this, especially considering the HRRR`s absence of any convective activity, but will retain 20 PoPs in case any differential heating boundaries can create updrafts strong enough to break the cap and access the ~1000 J/kg MLCAPE. Any activity that does exist should diminish quickly after sunset. Mostly clear skies expected tonight with lows a bit milder than previous nights with a more moist airmass and light SW flow. A few patches of fog cannot be ruled out. && .LONG TERM /TONIGHT THROUGH THURSDAY/... Issued at 328 AM EDT Fri Jul 12 2024 A more active period starts out the extended period as a shortwave moves over the area this weekend before a Clipper low brings more precip to the U.P. early next week; some very warm temperatures are expected Saturday and Sunday, and severe weather could be seen Sunday and Monday. Once we get behind the Clipper low though, expect high pressure ridging to finish out the rest of next week as a developing rex block develops eastwards into the Central U.S. The last of the afternoon convection ends early this evening as the sun sets and we lose the diurnal heating. With upper level ridging moving overhead and sfc level ridging holding on over our area tonight, expect mostly clear skies with low temperatures getting down to around 60 in the interior areas. Moving into Saturday, a shortwave trough looks to move into our area from the west. However, it will still have to fight against localized high pressure over the Upper Great Lakes throughout the day, which may limit the cloud cover and convection to only a few hours in the afternoon over the east and possibly late in the afternoon over the west. With weak warm air advection occurring throughout the day and southerly winds too, expect very warm conditions Saturday, with highs getting into the 80s across most of the area; some spots could get to or exceed 90, particularly the downslopes near Lake Superior (ex. L`Anse). Moving into the Saturday night, the chances for scattered showers and thunderstorms increases as the shortwave begins moving through the U.P.; while there looks to be enough instability to continue the convection through Saturday night, the available CAMs do show convective activity decreasing during the overnight hours. Shower and thunderstorm chances continue through Sunday as a secondary shortwave from the Northern Plains reinvigorates convection across the area. With bulk shear increasing to around 30 knots or more, and with model guidance uniformly showing MUCAPEs of 1000 J/kg or more over the area, some strong to severe thunderstorms could be seen. Looking at model soundings, it appears that the primary threat will be hail, with a secondary threat of severe winds as the convective instability is present above a thick layer of CIN in the lower levels. Another very warm day is in store for us Sunday, with highs pretty similar to Saturday as generally weak southwest surface flow dominates the U.P. A Clipper low brings additional showers and thunderstorms to our area early next week, although there is some model divergence as to when the convection associated with the low arrives; it could arrive as early as late Sunday night or as late as Monday afternoon. Regardless, more severe weather could be seen as bulk shear values increase in comparison to Sunday. However, CAPE values do not look to be as high. Therefore, with the better CAPE being in the interior areas Monday, any severe weather we do see will likely be relegated to this part of the U.P.; the primary threats will be severe hail and winds Monday. Besides maybe some light afternoon showers Tuesday, expect a drier and less active weather pattern for the last half of the extended period as high pressure builds in from the west. Behind the Clipper low, we could see temperatures drop to well below normal; the ECMWF EFI shows max temperatures in the -0.5 to -0.7 range Wednesday, meaning we could see highs only get into the 60s across some portions of the U.P. on that day. However, as we head towards the end of next week, expect the temperatures to gradually return to near normal as the surface ridging continues eastwards and allows warmer air to advect into our area. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 743 AM EDT Fri Jul 12 2024 LIFR flight conditions at SAW possible through mid-morning. Otherwise, expect VFR conditions to prevail for the duration of the TAF period. Isolated showers/thunderstorms cannot be ruled out with afternoon heating, but confidence is too low to include mention at this time. && .MARINE... Issued at 328 AM EDT Fri Jul 12 2024 Light winds of 20 knots or less are expected to continue today through this weekend until early next week as zonal flow aloft continues overhead for the next couple of days. That being said, a couple of shortwave lows may bring some scattered showers and thunderstorms over the lake late Saturday through Sunday; some of the thunderstorms could be strong to severe on Sunday. A Clipper low looks to bring additional showers and thunderstorms to the lake Monday into Monday night; some strong to severe storms could be seen, especially along the southerly nearshores with this Clipper. Behind the Clipper`s cold front, we could see northwesterly to west winds getting up to 20+ knots Monday night and Tuesday. Some patchy dense fog could be seen in the wake of each round of precipitation over the next several days. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Thompson LONG TERM...TAP AVIATION...JTP/TDUD MARINE...TAP