Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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066 FXUS63 KMQT 120855 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 455 AM EDT Wed Jun 12 2024 .KEY MESSAGES... - Strong and potentially severe storms possible Wednesday afternoon and evening across the west half of Upper Michigan. - Gusty winds expected Thursday along with lingering showers and thunderstorms. - Dry Friday and early Saturday before the return of showers and thunderstorms later in the weekend. - Warmer than normal temperatures frequent the forecast, with some areas approaching 90 for highs by next week. && .SHORT TERM /THROUGH TODAY/... Issued at 126 PM EDT Tue Jun 11 2024 A line of showers has progressed west to east through Minnesota and into western Lake Superior today. Dry air, apparent on GOES Water Vapor imagery, has resulted in a gradual diminishing trend to this line as its moved closer. Cloud cover has also expanded across western and central Upper Michigan, resulting in highs only in the low 60s interior west. Elsewhere, enough sunshine was observed to allow warming into the mid-upper 60s, except near Lake Michigan, which has been moderated by southerly flow off the bay and lake. These spots have barely climbed into the low 60s. As we progress through the remainder of the afternoon and overnight tonight, a weakening occluded front will continue pressing eastward, spreading cloud cover and light rain east across Upper Michigan. Only light accumulations are expected given the antecedent dry air. A rumble of thunder or two can`t be ruled out. Further upstream in northwestern Minnesota, increasing instability this afternoon may result in showers and thunderstorms developing and pressing east/southeast ahead of another shortwave rotating around a mid- level low in Manitoba. This may support another round of brief showers, perhaps a thunderstorm, late this evening in the Keweenaw/west and after midnight in the east before clearing skies spread overhead. Significant additional heating isn`t expected today, so expect highs mostly in the 60s to near 70F in some spots. Overnight lows should dip into the 50s, maybe high 40s in the interior west if we`re able to clear out earlier then expected. && .LONG TERM /WEDNESDAY THROUGH TUESDAY/... Issued at 421 PM EDT Tue Jun 11 2024 The active weather pattern across the CONUS continues through the long-term forecast. The main features of note at 500mb are a trough over southern Saskatchewan and a deep cutoff low off the coast of the Baja California, which will be the cause of active weather Wednesday night and over the weekend. Despite high pressures that generally follow both troughing features, the overall weather pattern through the long term is wetter than normal and warmer than normal, with some of the hottest temperatures of the year thus far forecast for Monday. Beginning Wednesday, as 500mb troughing still remains over the southern portions of the Canadian Prairie, a 110+kt jet streak at 250mb will move over ND and into MN. With mainly southwesterly flow, temperatures look to climb into the upper 70s and low 80s in the afternoon over the UP. Some cu development is expected late in the afternoon as not much capping is expected, through with synoptic lift far to the west and dry air at the surface, storms will struggle to initiate over the UP in the afternoon. A few of the CAMs do show some isolated high-base thunderstorms kicking off in the afternoon, but the primary threat for severe weather will come in the form of storms that fire off upstream in the MN Arrowhead. CAMs vary significantly on timing and intensity, but most show some showers crossing Lake Superior from the WNW and arriving over the western shores of the UP sometime in the 00Z-06Z timeframe. Northwesterly storms do tend to overperform over the UP climatologically, and these storms will have some decent shear to maintain themselves with as 0-6km shear values are around 50 kt Wednesday evening with 200+ 0-3km SRH. However, by the time the storms arrive, the MUCAPE will have diminished to 500 j/kg or below, so the intensity of the storms may struggle to reach severe criteria. Lots of variables still in play, but a few strong to severe storms are still expected Wednesday evening as a result. Once the showers move over the east half Thursday, winds veer westerly and northwesterly and 850mb cold advection will allow for some gusty winds to mix down to the surface. EFI shift of tails does indicate an unusually gusty day for Thursday, and the Euro ensemble gusts show potential for up to 35+ mph over the western, central, and interior eastern UP. A few lingering thunderstorms will be over the east, but with CAPE around 500 J/kg, storms will once again struggle to be particularly strong. Once showers move out of the UP entirely Thursday evening, dry weather will be over the UP through at least Saturday morning as ridging aloft builds in and supports a near-1020mb high pressure over the Upper Great Lakes. High temperatures slowly climb back into the upper 70s and lower 80s. RHs look to fall into the 40s and 30s, but with very light winds, weather should be benign to end the work week and begin the weekend. Meanwhile, the deep cutoff low over the Pacific will deamplify and shift northeast through the Rockies. The GEFS shows a low pressure will develop in the Canadian Prairie, with the GEFS suggesting a central pressure potentially below 990mb into the weekend. With high pressure shifting to the east, predominantly southerly low level flow will allow Gulf moisture to surge north, as shown in the NAEFS vapor transport being at the 90th percentile of climatology. As the weakening trough approaches the Upper Great Lakes and the cold front of the Canadian Low approaches, multiple lifting mechanisms for showers and thunderstorms will be present for the weekend. As the pattern is complex, details on the strength and timing of storms is tough to narrow down, so look for future forecast packages to gain clarity there, but with the available moisture to work with, ensembles do show about a 20% chance of daily precip totals to exceed an inch by Sunday, so some downpours could ruin some weekend outdoor plans. The gradual warmup continues into next week, with high 80s in the forecast for Monday, with widespread low to mid 90s in the 75th to 90th NBM percentiles. PoPs remain in the rest of the long term forecast as ensembles show a continued chaotic pattern through mid- June. Overall, the CPC outlooks the 8-14 day period as being more likely to be warmer than normal and wetter than normal. && .AVIATION /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 130 AM EDT Wed Jun 12 2024 VFR conditions will prevail at all terminals for the remainder of the TAF period. Skies are clearing out tonight, but a few passing midlevel clouds and some additional spotty shower activity is moving across Lake Superior already; a few drops are not out of the question at CMX over the next few hours, though confidence is low. After a sunny start, expect increasing cloud cover Wednesday afternoon ahead of another cold front. This may bring some afternoon showers/storms, but confidence is higher for convection to move in after 00Z. Otherwise, expect increasing southerly winds with gusts to 20kts possible mainly at IWD. && .MARINE... Issued at 454 AM EDT Wed Jun 12 2024 Southerly winds mainly 20 knots and lower will persist across Lake Superior into this afternoon. But, as the high pressure is replaced by a series of disturbances, an uptick in southerly winds of 20 to 25 knots can be expected late this afternoon. In addition, rain and general thunderstorms will be possible across the far western portions of the lake by late morning, overspreading the remainder of the lake by this afternoon. Some storms could become strong to severe, though, late this afternoon/evening mainly over the far western portions of Lake Superior. Thursday, winds will become west- northwesterly behind a cold front with 20 to 25 knots (isolated to 30 knots) outside of any additional thunderstorm chances through the day. By Friday, winds will return to less than 20 knots with the return of high pressure where they will stay until early Sunday morning. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JTP LONG TERM...GS AVIATION...LC MARINE...TDUD