Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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802 FXUS63 KMQT 060510 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 110 AM EDT Thu Jun 6 2024 .KEY MESSAGES... - Showery weather and much cooler conditions expected today through the weekend under the influence of low pressure. && .UPDATE... Issued at 1042 PM EDT Wed Jun 5 2024 There was quite a bit of afternoon/evening thunderstorm activity with reports of hail up to dime/penny size and even some tree damage in the Ironwood area. Thunderstorm intensity gradually waned over the past 2-3 hours to the point where small hail and gusty winds are now unlikely. The only remaining cluster of storms is north of Manistique and the most likely hazards are frequent lightning and briefly heavy downpours. Upstream radar/satellite don`t show much going on so expect the drying trend to continue overnight into Thursday morning as a progressively drier air mass builds over the area so have substantially reduced PoPs through the nighttime hours. There is commingled uncertainty with tonights low temperatures, cloud cover, and winds. Generally favor mostly cloudy skies and light winds keeping the boundary layer warmer around 50F, but there are breaks in the cloud cover that may allow for locally cooler spots dipping into the 40s. && .SHORT TERM /THROUGH THURSDAY NIGHT/... Issued at 431 PM EDT Wed Jun 5 2024 GOES-16 Visible imagery shows clearing skies along the MI/WI state line behind an advancing cold front, with the band of rain showers from that front now mainly confined to the eastern half of the UP. Through 1830Z, the only electrically active storm has been a sub- severe cell that started in southern Menominee County and has transited the Bay of Green Bay and is imminently arriving at the Garden Peninsula. Under cloudy skies for much of the day, highs are around 10 degrees cooler than yesterday, mainly in the low 70s. Attention turns upstream this afternoon to the clearing in the west, which already is showing signs of some cu development supported by diurnal heating and a secondary shortwave evident on RAP Analysis 500mb heights. The 12Z HREF showed much less available instability relative to yesterday`s storms with only around 500-1000 J/kg of SBCAPE available. Shear is right around what it was yesterday with around 20 kt of effective bulk shear and 50-100 0-3km SRH. It is worth noting that while instability is surface-based, the depth of the mixed layer at the surface is around 6,000 ft, so cloud bases are going to be relatively high. Reflectivity paintball plots in the HREF show that CI will begin in northern Wisconsin and push east into the UP around 20Z, somewhat losing energy as it progresses and maintaining cellular form. Thinking hazards are once again isolated damaging wind gusts and pea to quarter sized hail from "core dumps". Less total precipitation is expected with this round of showers, with HREF mean 6-hourly precipitation only around 0.2-0.4 inches. In the wake of showers, lows look to fall to the 50s tonight, with winds staying out of the west. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Issued at 431 PM EDT Wed Jun 5 2024 Flow over and around N America through early next week will feature pronounced high latitude blockiness. Through the remainder of this week and into the weekend, building mid-level ridging/positive height anomalies, first from ne through n central Canada and across the Arctic Ocean, and then over western N America will force mid-upper level troughing to develop from s central Canada across the Great Lakes/eastern U.S. This troughing will also force the mid-level low now over northern Saskatchewan/Manitoba to descend across the Great Lakes region beginning Thu. For Upper MI, this pattern evolution will lead to periods of showery weather and a period of blo normal temps (seasonably cool) thru early next week. However, the large scale pattern does suggest the potential of unseasonably cool days in the mix, particularly on Thu. Models have lacked run-to- run consistency and have been and continue to be quite varied on the details of the flow affecting Upper MI. So, the pcpn fcst has much more uncertainty than normal. Overall, expect many areas to be dry much of the time as showers are likely to be scattered in coverage on most days. Thu is likely to be the day with the most numerous shower coverage. With the mid-level trough weakening and shifting e early next week, dry and warmer weather is more likely to prevail for the first half of next week, although a few of the 00z models hint at another wave moving through the area in the Tuesday- Wednesday time frame that may bring the potential for some light shower activity. Beginning Thursday, the mid-level low now over central Canada will dive se across the Upper Great Lakes by Thu. A shortwave attached to the mid-level low circulation will track from northern MN se across Upper Mi in the late morning/afternoon. Forcing associated with this feature combined with the start of daytime heating will support a rapid development/expansion of showers during the morning. The showers should diminish in coverage over the w in the aftn in the wake of the wave. Considerable cloud cover will limit daytime heating/instability, so thunder potential is overall minimal. Fcst will only include a mention of thunder over the e and se fcst area due to a little more instability potential there before clouding over and development of widespread showers. Under considerable cloudiness, passing showers, rather stiff wnw winds and a 850mb thermal trough driving se into the area, it will be unseasonably cool for much of the area. Highs in the 50s F will likely be the rule across the w through n central ranging up to the lower/mid 60s F s central/se. Lakeside locations exposed to wnw winds across Lake Superior may not see max temps above 50F. W side of the Keweenaw likely to be coolest. Showers will diminish Thu night in the wake of shortwave, but won`t end, particularly over the e where showers may keep going in response to some isentropic ascent as warmer air to the n and ne weakly advects toward the thermal troffing over the area. On Fri, center of mid-level low drifts e toward southern Ontario. Weak shortwave ridging develops into western Upper MI between that low and another mid-level low over s central Canada. This is suggestive of fewer showers over western Upper MI on Fri compared to Thu, with more areas likely to be dry through the day. To the e, closer to the mid-level low, shower coverage will be greater. High temps on Fri will be coolest over the e where more clouds/shra are expected. Mid 50s to around 60F expected there. Low/mid 60s expected to the w, except closer to Lake Superior where temps will be in the 50s. Sat, models seem to be coming into a little bit better agreement on a shortwave trough moving through the area. MLCAPE values of 100-300 j/kg could maybe even support a rumble of thunder along the WI border and south central late morning into the afternoon. Expect scattered shower coverage with highs generally in the 60s, except for some 50s readings near Lake Superior in a continued nw flow. Sun, although model consistency isn`t great on exact details most of the models hint at another shortwave/mid-level trough axis moving through the area in the Sat night into Sunday time frame. Would expect at least isolated showers from feature perhaps aided by some weak isentropic ascent from the north as winds shifting from nw to n bring a pocket of warmer 850 mb air into the area. North flow off Lake Superior will result in 50s readings near the lake while 60s readings will be more common inland. With medium range models trending toward more ridging building over the area on Monday behind the exiting mid-level trough, would expect drier and warmer conditions on Monday with highs mostly in the 60s to lower 70s, with warmest readings inland toward the WI border. Models and ensembles then hint at a shortwave trough moving through in the late Tue into Wed time frame which could result in at least isolated showers again. Temps are expected to rebound to around normal values for this time of year with highs mainly in the 70s Tue into Wed. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 109 AM EDT Thu Jun 6 2024 VFR cigs/vsby continue tonight into Thursday, but a decreasing trend to MVFR cigs is expected on Thursday. At this time, expect MVFR cigs to be most persistent at IWD/CMX where upslope flow should result in bkn/ovc sky cover whereas scattered MVFR cigs are possible at SAW. The disturbance bringing lower clouds may also bring rain showers to IWD/CMX in the morning or early afternoon then during the afternoon at SAW. Aside from cloud/rain chances, west to northwest winds increase during the day with cold air advection compensating for cloudy skies allowing for mixing up to around 2kft. Gusts are forecast to increase to around 25 kts at IWD/SAW and 30 kts at CMX, but wouldn`t be surprised if gusts end up higher at CMX due to the long fetch off Lake Superior. && .MARINE... Issued at 431 PM EDT Wed Jun 5 2024 A low pressure trough moving in from the west could lead to a few stronger thunderstorms developing over MN and moving out across western Lake Superior late this afternoon/evening, posing a risk of locally strong wind gusts. Late tonight continuing into Fri, steady w to wnw winds generally at around 20kt with occasional gusts to 30kt will set in from w to e with the highest gusts over the east half. A slight diminishing of winds will occur over the weekend with sustained speeds falling back to around 15kt as winds shift from northwest to north-northwest on Sunday. North winds should diminish blo 15 kts on Monday as a high pressure ridge builds in from the northwest. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ UPDATE...EK SHORT TERM...GS LONG TERM...Voss AVIATION...EK MARINE...Voss