Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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382 FXUS63 KMQT 050906 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 506 AM EDT Sun May 5 2024 .KEY MESSAGES... -Dry conditions on Monday, though low winds and antecedent rainfall should broadly limit fire concerns. -Complex pattern setup for the midweek as multiple low pressure systems interact in the Midwest. Precipitation chances highest on Tuesday, but PoPs linger through the end of the week. Thunder potential is highest Tuesday into Tuesday night, although confidence is low. && .SHORT TERM /TODAY/... Issued at 455 AM EDT Sun May 5 2024 Ridging/subsidence has overspread the UP early this morning in the wake of a shortwave and associated cold front. Thus, clearing has commenced, and radiational cooling is rapidly dropping temperatures across the west/southwest. As a result, forecast update will be issued to match developing trends. In addition, patchy fog may need to be added along the WI/MI border of that western sector as well, will continue to monitor. For the remainder of today, height rises will result in clear skies and plenty of sunshine and a pleasant day with high temperatures climbing into the mid 50s to mid 60s (coolest along Keweenaw and Lake Superior lakeshore). Ample mixing and heating will contribute to RH values just below the 30% mark along the WI/MI border, but antecedent rainfall will help to mitigate the threat. && .LONG TERM /TONIGHT THROUGH SATURDAY/... Issued at 506 AM EDT Sun May 5 2024 Starting tonight, the shortwave just north of Lake Superior will be departing with sfc high pressure over the Great Lakes and mid level ridging over the Plains moving east toward the Great Lakes. This will result in a quiet night with lows in the mid 30s to low 40s. Meanwhile, a deep trough supplying the mid to late week weather will be situated over the Rockies, beginning to pivot northeast and take on a negative tilt. Ridging and high pressure over the Great lakes will result in an efficient mixing day up to 900 to 800 mb on Monday. Stronger winds mixing down are not the main concern, but lower dew points will be. With highs in the upper 50s to low 70s, (cooler by the lakeshores thanks to expected lake breezes) minimum RHs are expected around 30-35% in the interior during the afternoon/evening hours. With light winds mainly below 15 mph, the interior west is the only area that may get near borderline fire weather concerns. The trough is expected to pivot northeast over the Plains through Monday night with height falls supporting sfc low cyclogenesis. Meanwhile, a upper level jet left exit region traversing northeast Monday night into Tuesday will support additional cyclogenesis over the Central Plains. Monday night will still be dry in the UP with warmer temps than tonight in the 40s, warmer in the west as clouds increase ahead of the next system. While chances for showers increase in the far west early on Tuesday with increasing q-vector convergence, they likely will hold off until late morning or even the early afternoon due to the dry antecedent airmass. Model guidance in the last 24 hours has also trended toward the later arrival time for showers. Tuesday afternoon, a shortwave cycling around the newly reformed closed low will increase PVA and bring a stream of moisture noted in PWATS that erodes the dry airmass. The weaker southern low follows a similar path as the shortwave, moving northeast into the Upper Great Lakes Tuesday into Tuesday night while the strong sfc low associated with the closed mid level low spins over the northern plains. Meanwhile, a third sfc low looks to develop over the Southern Plains Tuesday night with the support of right entrance jet dynamics. Guidance is still fairly spread on the sfc low tracking through the Upper Great Lakes, with notable precip timing differences on Tuesday. There is a slight chance for thunderstorms on Tuesday and Wednesday, but confidence is diminishing given the spotty instability noted in the ensemble guidance; best chances are on Tuesday when the mid level lapse rates and bulk shear are higher. All together, showers are likely Tuesday afternoon into Tuesday night with slight chances for thunderstorms in the southern half of the UP. Given the current uncertainty, opted to leave the NBM PoPs as is. Chance PoPs hold through Thursday as the two western sfc lows move east and phase with each other Wednesday night over the Mid-Mississippi Valley before continuing east-northeast toward New England. Slight chance PoPs continue into the weekend as the pattern shifts and we track weak shortwaves traveling southeast from Canada into the Great Lakes Region. Longer range ensemble guidance hints at positive 500 mb height anomalies over the western U.S. with negative height anomalies moving toward the east coast toward the latter part of May. This leaves the Upper Great Lakes in a somewhat drier and cooler pattern reflected well in the CPC precip and temp outlooks, which favor below normal temps through mid May and below normal precip through the end of May. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 122 AM EDT Sun May 5 2024 Expect conditions to generally improve from MVFR to VFR early this morning over KSAW as the low-level cloud cover continues to leave the area. As for KCMX, some patchy FG looks to remain over the area until after sunrise this morning. KIWD could see some patchy fog as well; however, with low-level water vapor imagery showing very dry air overhead, we could see conditions remain VFR throughout the rest of the pre-dawn hours. VFR conditions remain over the TAF sites through the rest of today. && .MARINE... Issued at 506 AM EDT Sun May 5 2024 With high pressure building over the Great Lakes through Monday and stability increasing, winds are expected to remain mainly below 20 kts through Monday night. The exception to this would be over the far western portion of the lake near the Duluth Harbor where some northeast channeling on Monday may yield some gusts into the 20-25 kt range. A low pressure system over the Northern Plains strengthens Monday night while another low pressure moves northeast toward the Upper Great Lakes. The weaker low continues east over the Great Lakes Basin through Tuesday night. This results in winds increasing to around 20-30 kts over the west half and around 20 kts over the east by Tuesday afternoon. With the given stability, no gales are forecast at this time. Uncertainty in the forecast increases greatly into the later portions of the week, though winds are currently expected to be around 15 kts Tuesday night and 20 kts Wednesday through Thursday morning in the wake of the low pressure. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Small Craft Advisory until 2 PM EDT this afternoon for LSZ250- 251. Lake Michigan... None. && $$ SHORT TERM...TDUD LONG TERM...Jablonski AVIATION...TAP MARINE...Jablonski