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Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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612 FXUS63 KMQT 130846 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 446 AM EDT Tue Aug 13 2024 .KEY MESSAGES... - Warm and mostly dry weather today and Wednesday though some isolated lake breeze showers and thunderstorms are possible this afternoon. - Wet period later this week with showers and maybe some thunderstorms developing Thursday, continuing Friday, then lingering, but diminishing on Saturday. && .SHORT TERM /THROUGH THIS AFTERNOON/... Issued at 148 AM EDT Tue Aug 13 2024 Mostly clear skies look to continue across the area early this morning as a high pressure block moves overhead today. Satellite imagery is possibly picking up on the first patches of fog over Luce and Delta counties as of the time of this writing. However, given the dry airmass overhead, thinking fog will be limited to being patchy in nature before dawn this morning, and mainly being limited to the south central and east. Once the sun comes up, expect the fog to quickly erode away. Expect another mostly sunny/dry day again, with temperatures being almost a near repeat of yesterday (just maybe a hair warmer). There is also a small (10-20 percent) chance that we could see some showers and thunderstorms along the lake breezes this afternoon as there is ample instability in the atmosphere to work with. However, given the lack of a forcing mechanism, save for maybe the lake breeze, I have my doubts as to whether convection will fire off or not. In addition, CAMs soundings show the boundary layer being a tall inverted-v, meaning that there will be quite a bit of dry air to be overcome before precipitation hits the surface. However, this also means anything that gets started at the surface could keep building up to the tropopause given the lack of CIN in the atmospheric profile and the strong low to mid level lapse rates. Rain chances are zero percent behind the lake breezes this afternoon as the airmass will be too stable to support localized convection. && .LONG TERM /TONIGHT THROUGH MONDAY/... Issued at 444 AM EDT Tue Aug 13 2024 Positive height anomalies prevailing across Canada this week will suppress southward a branch of the westerlies across the Lwr 48 with that flow relatively progressive, lower amplitude for the next few days. Late this week, that flow will buckle with mid-level ridging building northward thru Alberta/Saskatchewan. In response, a group of shortwaves approaching the Great Lakes will consolidate into an amplifying trof into the Great Lakes region and eastern U.S. Fri thru early next week. For Upper MI, this evolution of the flow with troffing developing thru the Great Lakes region will bring shra to the area Thu thru Sat. While all day rain is not expected, potential right now appears high for all of Upper MI to see at least light to mdt rainfall over the course of the 3 days. Ensemble guidance suggests a 25-50pct probability of pcpn amounts of an inch or more by Saturday evening, greatest w to s central. The rainfall is needed as the pattern has turned drier over the last few weeks. A large portion of Upper MI is running at 25-70pct of normal rainfall over the last 30 days with the largest areas under 50pct over the w half of Upper MI. As for temps, above normal high temps will continue into Wed, then readings will be around normal or a little blo normal thru the weekend and into early next week as mid-level trof passes, followed by lingering nw flow. Beginning tonight, isold convection that develops this aftn may linger a little past 00z, but otherwise, the night will be dry. Some patchy fog may again develop tonight as we are now into late summer, and when quiet/cool nighttime conditions occur, patchy, shallow fog often forms, especially near swampy areas, rivers/streams, lakes due to their warm waters. Fog development would be more likely to occur if some rainfall occurs this aftn/early evening. Expect min temps mostly ranging thru the 50s F. Some of the traditional interior cool spots may slip into the upper 40s F, and some lakeside locations will stay above 60F. On Wed, concern is again the potential of isold aftn convection. However, models all show a drier column and weaker instability Wed aftn compared to this aftn. Although a few models do show isold convection developing, will ride with a dry fcst for Wed given the less favorable environment. High temps on Wed in many locations will be a few degrees warmer than today. Expect upper 70s to mid 80s F. Dry weather continues Wed night with temps falling back to the mid 50s to mid 60s F. During Thu/Thu night, mid-level troffing and a group of unorganized shortwaves progressing across s central Canada/Northern Plains will shift to the western Great Lakes. At the sfc, low pres will develop into WI. A healthy surge of isentropic ascent and 850-700mb moisture transport ahead of the trof may send associated shra into western Upper MI as early as around 12z on Thu. Otherwise, expect shra to progress w to e across the area as the forcing advances eastward during Thu and thru Thu night. Precipitable water increasing to 150- 170pct of normal, weak instability developing aloft, and warm cloud depths increasing to around 12kft to increase warm rain processes will combine to support some potential of locally hvy rainfall. Thunder likely to be limited to isolated coverage given the weak instability. Showers will continue on Fri as troffing/potential weakly closed off mid-level low drift over the western Great Lakes while associated sfc low slowly moves e across northern WI or Upper MI. With ocnl shra and abundant cloud cover, high temps should be held to mostly the upper 60s/lwr 70s F. If sfc low tracks across WI/southern Upper MI, could end up being a gloomy, low stratus kind of day across the w and n central with upslope ne to n winds. As the troffing continues drifting eastward on Sat, expect shra coverage to diminish compared to Fri. Abundant cloud cover should remain, holding high temps to the upper 60s to mid 70s F. Dry weather should then set in for Sun with trof slipping a little farther e. Mon should also be a dry day, then next shortwave dropping se in continued nw flow downstream of ridging from NM/TX to the NW Territories may approach on Tue or Wed, bringing the next chc of shra/tsra. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 305 AM EDT Tue Aug 13 2024 UPDATE: Current satellite and webcam imagery shows patchy fog failing to develop up into the north central U.P. early this morning. Therefore, I`ve removed the FG chances from KSAW. -TAP Mainly VFR conditions for the duration of the TAF period. However, there is a chance for MVFR or worse fog at SAW again early this morning. Will highlight this in a tempo from Tue 08-12Z. Elsewhere, confidence remains too low to include mention of fog at IWD or CMX. And probabilities are also too low for shower/thunderstorm mention this afternoon at any TAF site at this time. && .MARINE... Issued at 444 AM EDT Tue Aug 13 2024 Light winds less than 15kt will continue across Lake Superior today under sfc high pres. Winds will increase slightly on Wed, but still under 20kt as the high pres begins to slip eastward. Thu/Fri, low pres will develop e and ne into WI, bringing increasing easterly winds to Lake Superior. Expect winds to occasionally gust to 20- 25kt, particularly Thu aftn and Thu night. Exact track of the sfc low will determine whether these stronger wind gusts continue on Fri. As the low departs, n to nw winds may gust to 20-25kt late Fri into Sat, mainly across the e half of Lake Superior. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...TAP LONG TERM...Rolfson AVIATION...TAP MARINE...Rolfson