Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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720 FXUS63 KMQT 120717 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 317 AM EDT Sun May 12 2024 .KEY MESSAGES... -Isolated pockets in the south central could (40% chance) see elevated fire conditions ahead of the showers and thunderstorms this afternoon. -Scattered thunderstorms develop this afternoon into early evening, especially south central. There is a marginal risk (5%) of large hail and/or damaging winds south central. -Dry weather returns late tonight, continuing through Wednesday afternoon. && .SHORT TERM /THROUGH TONIGHT/... Issued at 316 AM EDT Sun May 12 2024 As a shortwave over northern Manitoba heads into northern Ontario this morning, strong theta-e advection and a low-level jet at 35 to 45 knots is bringing some sprinkles across the area early this morning over the western U.P. As cloud cover and warm air advection increase over the area early this morning, we`ve seen temperatures across the area stabilize and slightly rise. Therefore, we`ve almost certainly hit our low temperatures already, ranging from the mid 30s over the interior east to the mid 50s over the far west. As the sprinkle activity moves into the eastern U.P. after dawn this morning, expect to see a little bit of clearing over the west and central. This will allow the sunlight to increase the temperatures at the surface while dewpoints remain generally steady, creating a strong inverted-v sounding near the surface. This is most pronounced over the south central, where RHs could fall down to around 30%. We could (40% chance) see a spot or two in the south central hit elevated fire weather conditions as the highs today look to get to around 80F and winds could gust up to as high as 20-25 mph from the southwest before a cold front moves through this afternoon. However, given the likelihood and possible coverage of the potential elevated fire weather conditions, no notification will be sent this morning. However, fire weather isn`t the only concern over the south central today. With CAMs model soundings showing convection becoming surface- based over the south central this afternoon up to around 1200 J/kg and 0-6 km bulk shear vectors being around 35 to 45 knots perpendicular to a lake-breeze aided cold front moving through Upper Michigan this afternoon, we could see marginally severe wind and hail this afternoon into early this evening across the south central (5% chance). Hail chances are aided by the wetbulb zero heights being in the 7-9 kft range and severe wind chances are increased by the strong lapse rates and evaporation near the surface ahead of the cold front. Thinking the storms will remain fairly discrete this afternoon into this evening over the central and east, but they will mainly be restricted to the cold front as it passes through Upper Michigan. Therefore, we could see the storms congeal into a more linear state late this afternoon into early this evening. As the cold front continues to push south and east out of area this evening, expect the showers and thunderstorms to roll out of area with it. Therefore, the severe weather threat looks to end before midnight tonight, with skies clearing out behind the cold front. Due to the clear skies tonight, expect low temperatures to be around 40, save for around Menominee where lows look to be a few degrees warmer. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... Issued at 331 PM EDT Sat May 11 2024 A couple cold fronts will press through the Upper Great Lakes Sunday evening, allowing a cool to seasonable airmass to break into the region through at least mid-week. Ahead of the initial cold front on Sunday, afternoon shower and thunderstorm development may occur if we`re able to destabilize enough following the Sunday morning isentropically/warm frontally forced showers. By 0z Sunday and the start of this forecast period, the cold front looks to be draped across the central UP with the aforementioned shower/thunderstorm region out ahead stretching from Menominee County northeastward into the eastern UP. The environment at this point should be less conducive for any new convective development given the quickly waning influence of the day`s diurnal heating. However, if a strong or severe storm does develop earlier, guidance suggests enough deep layer shear could sustain updrafts into the evening hours. However, the window will be short lived given the cold front`s fast eastward progression. By 3z, CAMS all suggest convective activity should be outside of the forecast area. Behind the cold front, a dry airmass will press into the region while a secondary cold front moves through after midnight Sunday night. This, in addition to surface ridging building over the area, will sustain a dry couple of days for the forecast area. The daytime high temperature gradient Monday and Tuesday should stretch from near 50F by Lake Superior to the low-mid 60s across the south- central. On Wednesday, more widespread 60s are expected, with most areas outside of the immediate lakeshores and Keweenaw looking to climb into the low-mid 60s. Overnight lows should be mostly in the 30s, with chances for sub-freezing temperatures in the interior- central spots (20-30% chance). Fire weather concerns should be mitigated by the near to slightly cooler then normal conditions and light winds these days. But daytime mixing into a dry airmass aloft may support RH values nearing 30% for some interior central and west locations. Mid-level ridging shifts through the region on Wednesday followed by a shortwave pressing through Minnesota/western Ontario Wednesday night. Consensus among the 12z deterministic guidance suite has this pressing into our forecast area Thursday, supporting another round of showers through the day. This contrasts some with the GEFS, EC, and GEPS ensemble systems, where some members suggest precip could start Wednesday night. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 112 AM EDT Sun May 12 2024 VFR conditions will prevail thru this fcst period at IWD/CMX/SAW. As low pres drops into far northern Ontario tonight, a low-level jet will develop into Upper MI late tonight into Sun morning, resulting in 2-6hrs of LLWS at all terminals, lasting longest at IWD. The low- level jet will also generate sct showers, but confidence in a shower passing over any of the terminals is low. Not expecting conditions to drop out of VFR if a shower does occur. More showers/possible t-storm will develop Sun afternoon across central Upper MI, possibly affecting SAW before showers sag south in the evening. && .MARINE... Issued at 331 PM EDT Sat May 11 2024 Winds are mainly expected to remain below 20 kts through the entire forecast period, with some exceptions. A warm front will lift through the lake late tonight and early Sunday. Ahead of and behind the front, some isolated 20-25 kt wind gusts will be possible. The stronger pressure gradient will be Sunday across the east half and behind the warm front; however, the increasingly stable airmass over the lake should work against mixing the stronger southerly winds to the surface. Given the environment, higher reporting platforms would be more likely to observed these stronger winds than the surface buoys. A cold front will press from west to east through Lake Superior through the day as well. A shower or thunderstorm can`t be ruled out by afternoon across the east half, but with the focus for convection being over Upper Michigan and not Minnesota, the probability is low (20-30%). Behind the front, high pressure will settle over the lake, supporting a few days of mostly 20kts or less over the lake through at least midweek. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... Small Craft Advisory from 2 PM this afternoon to 11 PM EDT this evening for LMZ248-250. && $$ SHORT TERM...TAP LONG TERM...JTP AVIATION...Voss MARINE...JTP