Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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218 FXUS63 KMQT 070954 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 554 AM EDT Tue May 7 2024 .KEY MESSAGES... - An approaching low pressure system brings a line of showers northward into the U.P. this afternoon. Breezy southeast winds are also expected today, gusting up to 25-35 mph with stronger winds in the west. - A brief period of elevated fire weather conditions is possible preceding the showers in the northern half of the U.P. except for the Keweenaw. - Multiple passing low pressure systems will keep rain chances in the forecast through the beginning of the weekend. && .SHORT TERM /THROUGH THIS AFTERNOON/... Issued at 437 AM EDT Tue May 7 2024 Right now the UP is dry and fairly quiet with light south to southeast winds. Current RAP analysis shows the mid level ridging over the Great Lakes that is providing us this quiet period. A closed low is analyzed over western South Dakota with a shortwave to its south over Kansas and the Panhandles of Texas and Oklahoma. The sfc features include a high pressure over northeastern Ontario which extends into the Lower Great Lakes and two low pressure systems out over the west. The northern low is the stronger of the two at 981mb and the second one (which is associated with the shortwave) is located at 997mb over eastern Kansas. With the high pressure diminishing as it retreats northward and ridging still holding on through this morning, dry weather will persist with mild temps in the 40s (cooler in the east). Today brings precip back into the forecast. The closed low and associated sfc low will spin over the Dakotas, slowly weakening. Meanwhile, the central plains shortwave pivots northeast toward the UP by this evening. The weaker sfc low will follow a similar path, occluding as it approaches, ending up over Lake Michigan by the evening. The occluded front is expected to lift from south to north this afternoon bringing a line of showers with it. Showers along the WI/MI state line are expected to begin around 1-2 PM EDT, reaching a line between Houghton/Marquette/Manistique by around 6 PM EDT, then the rest of the UP around 7-9 PM EDT. Instability will be lacking as indicated by the 5/7 0Z HREF MUCAPE with values around 100 j/kg over the south central. Also bulk shear and lapse rates will low around 20-35 kts and 6C/km respectively. Given the set up, strong thunderstorms can be ruled out, but a few rumbles of thunder are possible in the south and along the WI/MI state line. Ahead of the showers, some mixing is expected to bring some lower RHs and breezy southeast winds. Highs will occur earlier in the afternoon in the south due to the front lifting in. Highs in the 60s are expected with upper 50s near the lakeshores; warmer temps hold on longer in the eastern UP. The brief period of mixing ahead of precip will result in lower RHs dipping into the 20s to low 30s in the northern half of the UP save for the Keweenaw. Gusty southeast winds up to 20-30 mph with a few gusts to 35 mph possible over the far west and in the Keweenaw will also be a fire weather concern. That said, this period of elevated fire weather conditions will only last 3 to 6 hours and anticipated precip will bring some relief with a few hundreths to 0.35" of rain; areas in the south central UP may see up to 0.5-0.75" by this evening. With the uncertainty on the duration of elevated fire weather conditions and the period being brief to begin with, no SPS was issued. && .LONG TERM /TONIGHT THROUGH MONDAY/... Issued at 536 AM EDT Tue May 7 2024 Much of the first half of the extended period will be influenced by a trough as it continues its progression through the Northern Plains and Upper Midwest. By this evening, the trough will have already evolved into a closed low with a shortwave rotating northeast along the trough. Meanwhile, the left exit region of a potent 140 kt 300mb jet will combine with the shortwave and an occluded surface front to provide just enough lift for some isolated thunderstorms across the southern half of the UP through the evening. With HREF MUCAPE values struggling to even get above 100 J/kg though and not much farther than Menominee County, confidence is low in any convective activity beyond that. Nonetheless, rain showers will persist through tonight and Wednesday until the surface low is able to exit the northern Great Lakes Region. Wednesday night, look for a lull in activity across Upper Michigan as the aforementioned closed low induces brief ridging over the region as it slides southeastward. With a surface low just ahead of it, deterministic GFS and ECMWF want to bring some rain chances back into the south and eastern portions of Upper Michian on Thursday. But, this is low confidence since just even the slightest southward shift in the track could result in a dry forecast on Thursday. Confidence does increase in a dry forecast though by Thursday night and into Friday as ridging strengthens ahead of yet another Clipper. This disturbance will keep rain in the forecast through Saturday when much of the same occurs, a lull before the next closed low drops into Ontario. This is where model consistency becomes poor though with the ECMWF favoring more of a southerly track than the GFS. Temperatures through Saturday will hover around normal with highs generally in the 50s and 60s. But, a warmup is likely late in the weekend/early next week as WAA advection intensifies ahead of impending Ontario low. Overnight lows will generally be in the 40s except for some mid 30s Wednesday night and low 30s on Thursday night across the interior west. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 121 AM EDT Tue May 7 2024 As an occluding front approaches from the south today, expect LLWS to fire up over KIWD at 06z this morning, continuing until the mid- morning hours. Otherwise, the VFR conditions deteriorate this afternoon as rain showers along the occluding front move over the area from southwest to northeast. As we move into the overnight hours, expect the conditions to worsen down to LIFR/IFR across the TAF sites. While LLWS could be seen at all of the TAF sites during the daylight hours into the early evening hours today, given that some mixing is expected in the boundary layer to the end of the TAF period, no LLWS is expected. However, should there be breaks in the mixing during the daylight and evening hours, expect LLWS across the terminals during those breaks. && .MARINE... Issued at 553 AM EDT Tue May 7 2024 Northeast to east winds will increase to 25 to 30 knots later this morning across the western half of the lake as a low pressure system approaches Upper Michigan. Some of the winds along the Minnesota shorelines could exceed 30 knots, but they should remain below the 34 knot threshold. Winds across the eastern half of the lake are expected to be in the 20 to 25 knot range. After a break in the 20+ knot winds tonight, periodic chances for 20 to 30 knot winds will return as multiple low pressure systems pass through Upper Michigan through Saturday. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Small Craft Advisory from 1 PM to 5 PM EDT this afternoon for LSZ243. Small Craft Advisory from 1 PM this afternoon to 8 PM EDT this evening for LSZ244>246. Small Craft Advisory from 1 PM to 4 PM EDT this afternoon for LSZ247. Lake Michigan... None. && $$ SHORT TERM...Jablonski LONG TERM...TDUD AVIATION...TAP MARINE...TDUD