Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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106 FXUS63 KMQT 211023 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 623 AM EDT Sun Apr 21 2024 .KEY MESSAGES... - Elevated fire weather conditions today and Monday, especially in the west and central. - Showers return Monday night. - Temperatures warming through Monday, but becoming much colder and breezy Tuesday with rain showers turning to snow showers. && .SHORT TERM /THROUGH THIS AFTERNOON/... Issued at 241 AM EDT Sun Apr 21 2024 Upper air pattern consists of a broad 500 mb trough across the Great Lakes region with a ridge in the northern and Canadian Rockies. This ridge moves into the northern plains by 00z Mon. A dry and weakening cold front moves through the area today. Rh`s get down to around 25 percent this afternoon. This is some concern with winds being gusty, but with recent wet trends, this should keep fire weather concerns down for now. Will mention in the hwomqt product and also send out an email to our fire weather partners to let them know about the low rh values this afternoon. && .LONG TERM /TONIGHT THROUGH SATURDAY/... Issued at 359 AM EDT Sun Apr 21 2024 Midlevel troughing will pivot into eastern Canada tonight, while shortwave ridging builds in over the local area through Monday. Pressure falls over the northern Plains in response to an approaching compact upper low will result in return flow building into the UP late tonight into Monday. Surface ridge will be in place initially Sunday night with good radiational cooling conditions, although the commencement of return flow will put a floor on lows and maybe allow temps to rise a couple degrees over the west. Coolest temps should therefore be across the interior east with some lower 20s possible. Lows range through the 20s elsewhere, low 30s along the western Superior shoreline. Southwesterly winds combined with deep mixing up to 800 mb will result in a nice boost in temps Monday. Forecast went a bit above NBM guidance with mainly 60s, but cooler in the 50s downwind of Lake Michigan. The deep mixing should tap into very dry air aloft and result in low RH values mainly 20- 30% (lowest interior west and central). Winds aloft are not overly strong, but the deep mixing should result in gusts of 20-25 mph through the day. This, combined with a couple of good drying days over the weekend, should result in elevated fire weather conditions for most of the UP except for the area immediately downwind of Lake Michigan. The gradient flow should keep the Superior lake breeze at bay, so the mild temps should extend close to the shoreline. Mid/high clouds will thicken through the day and eventually deeper moisture will win out as low-level jet magnitudes increase, and a band of showers is likely to cross the UP Monday night. Low pressure will cross Lake Superior from west to east late Monday night into Tuesday, pushing a cold front southward through the UP through the day Tuesday. This front will pack a punch with trajectories behind the front emanating from cold high pressure centered over southern Hudson Bay. Highs will be in the morning with temps falling from north to south through the day for most of the UP, possibly around a 20F drop through the day. NBM guidance does not have a good handle on the expected sharp temp drop, so a non- bias corrected dataset was preferred. The frontal forcing and lake enhancement should lead to a band of showers with rain turning to snow behind the front. Amounts are expected to be a dusting up to maybe an inch over the higher terrain. If it were a month or two earlier, would be more concerned about icy road conditions developing given the steep temp drop, but the late April sun angle and temps not falling too far below freezing if at all during the snowfall makes me skeptical that there will be issues. Still, the temp drop will be a shock to the system with apparent temps falling into the 20s and teens for most of the UP by the evening with strong northerly winds gusting to 30 mph. Ahead of the front, it could be a sneaky warm day over the south central with temps possibly reaching the low 60s due to the later frontal passage there. A chilly airmass will continue to reside over the area Tuesday night into Wednesday with the Hudson Bay high building in. Skies will be clear amid the dry and cold airmass, however. The airmass moderates Thursday into Friday as the high shifts east, with temps rebounding to near/above normal values. Indications are that moisture will quickly increase Friday night into next weekend as the Gulf opens ahead of a negatively tilted trough ejecting out of the central Plains. Periods of rain are likely Friday night into Saturday. && .AVIATION /12Z TAFS THROUGH 12Z MONDAY/... Issued at 623 AM EDT Sun Apr 21 2024 Although a weakening cold front will drop into the area today, VFR will prevail thru this fcst period at IWD/CMX/SAW. && .MARINE... Issued at 359 AM EDT Sun Apr 21 2024 Winds should remain at or below 20 kt through Monday, except over the far eastern lake this afternoon as a cold front brushes past and maintains instability with northwesterly wind gusts to 25 kt. A low pressure system will track west to east across the lake Monday night, with strong northeasterly to northerly winds developing behind it late Monday night into Tuesday. There is a brief window for gales 35-40 kt mainly Tuesday morning along the Keweenaw up toward the northern Lake Superior buoy, with 50-70% probabilities in this area. Elsewhere, probability for gales are 20-50%, with gusts more likely topping out around 30 kt through the day Tuesday. Winds will gradually diminish Tuesday night as high pressure builds in and results in light winds Wed/Thu. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Small Craft Advisory until 8 AM EDT this morning for LSZ243- 244. Small Craft Advisory until 2 AM EDT Monday for LSZ250-251. Lake Michigan... None. && $$ SHORT TERM...07 LONG TERM...Thompson AVIATION...07 MARINE...Thompson