Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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757 FXUS63 KMQT 231935 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 335 PM EDT Thu May 23 2024 .KEY MESSAGES... - Slight chance for light showers along the WI/MI state line through this evening. - Another shortwave and low pressure system will bring another round of showers and a slight chance (around 20% chance) for some thunder to Upper Mi late Friday into early Saturday. - There will be more opportunities for rain next week although model uncertainty leads to low forecast confidence on timing/extent. && .SHORT TERM /THROUGH TONIGHT/... Issued at 318 AM EDT Thu May 23 2024 RAP analysis shows a stacked closed low north of Lake Superior with central surface pressure near 994 mb. While a tight pressure gradient and tapping into a LLJ caused windy conditions earlier, the weakening low departing the region is allowing winds to come down somewhat, though some gusts to 25 mph may linger throughout the morning. Despite weakening surface flow, diurnal heating will support cu development with a few CAMs suggesting some shower development in the south and interior west. Instability has trended lower with the last 24 hours of model runs, so confidence in showers of any strength is low, but left some 15-24% PoPs from 18Z to 02Z. Expect highs mainly in the mid 60s, close to the climatological normal for this time of year. The exceptions will be locations downwind of Lake Superior that will have highs near 60 and the south, which bias- corrected guidance suggests mid- to upper-70s may be observed between Menominee and Iron Mountain. Overnight, winds turn easterly and northeasterly in response to a 00Z GEFS-mean 997 mb low approaching Minnesota. Previous forecasts had rain arriving in Ironwood by 12Z Friday, but virtually all of the most recent model runs at varying resolutions have backed off on the initial line of precipitation, so PoPs have been largely removed from the overnight time period. Low temperatures will be in the 40s, near normal for this time of year. && .LONG TERM /FRIDAY THROUGH THURSDAY/... Issued at 335 PM EDT Thu May 23 2024 Wet, active weather continues on and off through the extended period before we briefly dry out for the middle of next week. By Friday, the focus will shift to the next shortwave emerging from the western CONUS mid-upper level trough. This shortwave lifts NE through the Plains and Upper Great Lakes, eventually swinging into Manitoba and Ontario phasing once more with the broader troughing over the western CONUS/Canadian Prairies. Increasing isentropic ascent, 850 mb theta advection and moderate q-vector convergence out ahead of the shortwave will lead to another quick round of showers across the area beginning late Friday afternoon in the western UP and spreading eastward during the evening. Instability off soundings looks pretty minimal, with just a few hundred j/kg of CAPE indicated in HREF plots, so thunder should be fairly limited. Otherwise, guidance continues to favor widespread rain amounts of 0.10-0.25in, but EPS ensembles also show probabilities of 40-60% for amounts of 0.50in or more south central and southeast. Showers quickly exit eastward during the pre-dawn hours of Saturday with clearing skies expected as drier air works in. Saturday should be dry with ridging/subsidence behind the exiting shortwave. Expect partly cloudy skies and seasonable temperatures for the rest of the day with highs mostly in the 60s with a few cooler mid 50s readings near Lake Superior. There remains quite a bit of uncertainty in the Sunday-Tuesday time frame regarding the track/strength of the next western CONUS wave and developing cyclone. This ejects NE from the lee of the southern Rockies into the Great Lakes region late weekend into early next week, but many of deterministic models (particularly the GFS, UKMET and Canadian) as well as ensembles continue to flip-flop on the exact track with some runs taking a deep system as far north as the Straits, and others suppressed more over the southern or central Lower Peninsula and coming in comparatively weaker. A more southerly route would have little if any wind and rain impacts to the UP, while the more NW route would bring a chance for more significant rainfall as well as gusty winds. The ECMWF, on the other hand, has been the most consistent of the models advertising generally a more phased and deeper system for the last several runs with a more northern/western track through the Central Great Lakes, and thus, greater rain and wind impacts for Upper Mi in the late Sunday into Memorial Day time frame. Given the huge spread depicted in the tracks of the ensemble members it`s still too soon to latch onto any one model solution with great certainty, thus leading to poor forecast confidence during this time frame. For now, will continue to lean on the model blend for forecast details and wait a bit longer for models to sort out their continuity/consistency issues and hopefully come into better agreement over the coming days. PoPs persist into Tuesday as the system moves into Quebec, and associated wraparound moisture curls into the area while another shortwave ripples through. Most of the models and ensembles do seem to be in general agreement showing a trend toward ridging and drier conditions for Wednesday into Thursday next week. Otherwise, expect more or less seasonable temperatures through the forecast period. && .MARINE... Low pressure that impacted the area over hte past couple of days continues to weaken over James Bay while a weak high pressure ridge builds over the Great Lakes. Winds have been on the decrease today in response, still gusting to 20-25 knots out of the west in the eastern portions of the lake, but dropping below 20 knots to the west. Winds finally fall below 20 knots to the east later this evening. The period of light winds doesn`t last long over the western lake, however, as northeast winds will begin to ramp up to 30 knots late tonight into Friday in advance of another low pressure lifting from the Northern Plains towards Lake Winnipeg. Guidance indicates around a 60-70% chance for gales Friday afternoon through the early evening over the western quarter of Lake Superior. East to southeast winds gradually increase over the east half of the lake on Friday but generally stay 20 knots or less, but 25kt gusts will then become possible for a brief period into the evening and overnight hours. Winds over the west half becoming southwest behind the low and the passage of its cold front late Friday night into Saturday and generally stay in the 15 to 25 knot range. Winds decrease late Saturday behind the exiting system, then expect light winds of 20 knots or less across Lake Superior for the rest of this weekend as a high pressure ridge builds over the area. Looking ahead to early next week, another system moving out of the Plains will head towards the Great Lakes. This could present another opportunity for gusty winds, but confidence is low given quite a bit of uncertainty on the exact storm track. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... High Wind Watch from 6 AM EDT Wednesday through Wednesday evening for MIZ001-003. Wind Advisory from 9 AM EDT /8 AM CDT/ to 10 PM EDT /9 PM CDT/ Wednesday for MIZ002-009. Lake Superior... Gale Warning until 8 PM EDT /7 PM CDT/ Wednesday for LSZ162. Gale Warning from 7 AM EDT /6 AM CDT/ to 8 PM EDT /7 PM CDT/ Wednesday for LSZ240-241. Gale Warning from 10 PM this evening to 11 PM EDT Wednesday for LSZ242>244-263-264. Gale Warning from 2 AM to 11 AM EDT Wednesday for LSZ245>251- 265>267. Lake Michigan... None. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 142 PM EDT Thu May 23 2024 VFR flight conditions are expected to prevail throughout the duration of the 18Z TAF period. While some lingering gusts in the 20-30 kt range are expected at CMX yet this afternoon, west winds are expected to taper off into tonight as they become northerly. This afternoon should see some scattered diurnal cumulus, but no precip is expected at any of the TAF sites. LLWS is possible at IWD Friday morning, however confidence was too low to include in this TAF issuance. Precip and lower cigs with the next low pressure system look to hold off until after this TAF period ends. && .MARINE... Issued at 335 PM EDT Thu May 23 2024 Wet, active weather continues on and off through the extended period before we briefly dry out for the middle of next week. By Friday, the focus will shift to the next shortwave emerging from the western CONUS mid-upper level trough. This shortwave lifts NE through the Plains and Upper Great Lakes, eventually swinging into Manitoba and Ontario phasing once more with the broader troughing over the western CONUS/Canadian Prairies. Increasing isentropic ascent, 850 mb theta advection and moderate q-vector convergence out ahead of the shortwave will lead to another quick round of showers across the area beginning late Friday afternoon in the western UP and spreading eastward during the evening. Instability off soundings looks pretty minimal, with just a few hundred j/kg of CAPE indicated in HREF plots, so thunder should be fairly limited. Otherwise, guidance continues to favor widespread rain amounts of 0.10-0.25in, but EPS ensembles also show probabilities of 40-60% for amounts of 0.50in or more south central and southeast. Showers quickly exit eastward during the pre-dawn hours of Saturday with clearing skies expected as drier air works in. Saturday should be dry with ridging/subsidence behind the exiting shortwave. Expect partly cloudy skies and seasonable temperatures for the rest of the day with highs mostly in the 60s with a few cooler mid 50s readings near Lake Superior. There remains quite a bit of uncertainty in the Sunday-Tuesday time frame regarding the track/strength of the next western CONUS wave and developing cyclone. This ejects NE from the lee of the southern Rockies into the Great Lakes region late weekend into early next week, but many of deterministic models (particularly the GFS, UKMET and Canadian) as well as ensembles continue to flip-flop on the exact track with some runs taking a deep system as far north as the Straits, and others suppressed more over the southern or central Lower Peninsula and coming in comparatively weaker. A more southerly route would have little if any wind and rain impacts to the UP, while the more NW route would bring a chance for more significant rainfall as well as gusty winds. The ECMWF, on the other hand, has been the most consistent of the models advertising generally a more phased and deeper system for the last several runs with a more northern/western track through the Central Great Lakes, and thus, greater rain and wind impacts for Upper Mi in the late Sunday into Memorial Day time frame. Given the huge spread depicted in the tracks of the ensemble members it`s still too soon to latch onto any one model solution with great certainty, thus leading to poor forecast confidence during this time frame. For now, will continue to lean on the model blend for forecast details and wait a bit longer for models to sort out their continuity/consistency issues and hopefully come into better agreement over the coming days. PoPs persist into Tuesday as the system moves into Quebec, and associated wraparound moisture curls into the area while another shortwave ripples through. Most of the models and ensembles do seem to be in general agreement showing a trend toward ridging and drier conditions for Wednesday into Thursday next week. Otherwise, expect more or less seasonable temperatures through the forecast period. && .MARINE... Low pressure that impacted the area over hte past couple of days continues to weaken over James Bay while a weak high pressure ridge builds over the Great Lakes. Winds have been on the decrease today in response, still gusting to 20-25 knots out of the west in the eastern portions of the lake, but dropping below 20 knots to the west. Winds finally fall below 20 knots to the east later this evening. The period of light winds doesn`t last long over the western lake, however, as northeast winds will begin to ramp up to 30 knots late tonight into Friday in advance of another low pressure lifting from the Northern Plains towards Lake Winnipeg. Guidance indicates around a 60-70% chance for gales Friday afternoon through the early evening over the western quarter of Lake Superior. East to southeast winds gradually increase over the east half of the lake on Friday but generally stay 20 knots or less, but 25kt gusts will then become possible for a brief period into the evening and overnight hours. Winds over the west half becoming southwest behind the low and the passage of its cold front late Friday night into Saturday and generally stay in the 15 to 25 knot range. Winds decrease late Saturday behind the exiting system, then expect light winds of 20 knots or less across Lake Superior for the rest of this weekend as a high pressure ridge builds over the area. Looking ahead to early next week, another system moving out of the Plains will head towards the Great Lakes. This could present another opportunity for gusty winds, but confidence is low given quite a bit of uncertainty on the exact storm track. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... High Wind Watch from 6 AM EDT Wednesday through Wednesday evening for MIZ001-003. Wind Advisory from 9 AM EDT /8 AM CDT/ to 10 PM EDT /9 PM CDT/ Wednesday for MIZ002-009. Lake Superior... Gale Warning until 8 PM EDT /7 PM CDT/ Wednesday for LSZ162. Gale Warning from 7 AM EDT /6 AM CDT/ to 8 PM EDT /7 PM CDT/ Wednesday for LSZ240-241. Gale Warning from 10 PM this evening to 11 PM EDT Wednesday for LSZ242>244-263-264. Gale Warning from 2 AM to 11 AM EDT Wednesday for LSZ245>251- 265>267. Lake Michigan... None. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Warning from 11 AM EDT /10 AM CDT/ to 8 PM EDT /7 PM CDT/ Friday for LSZ162. Lake Michigan... None. && $$ SHORT TERM...GS LONG TERM...LC AVIATION...Jablonski MARINE...LC