Area Forecast Discussion
Issued by NWS Gaylord, MI
Issued by NWS Gaylord, MI
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739 FXUS63 KAPX 171707 AFDAPX Area Forecast Discussion National Weather Service Gaylord MI 107 PM EDT Mon Jun 17 2024 .KEY MESSAGES... - Hot and humid temperatures as well as showers and thunderstorm chances this afternoon and evening - Very hot, humid conditions expected to continue through the middle of the week. - Chances for showers/storms at times this week. && .UPDATE... Issued at 947 AM EDT Mon Jun 17 2024 Warm and humid airmass now well established across the northern Great Lakes. Despite this abundant moisture, conditions remain dry with no appreciable forcing to drive shower development. That may change some this afternoon as current sun-filled skies drive the development of low level instability. No inhibition to moist updrafts to be found, but lack of trigger for updrafts to focus on remains hard to come by. Still think the development of a backed wind field off northern Lake Huron will allow some scattered moist convection this afternoon...especially across eastern upper and northeast lower Michigan. Will also need to watch movement of outflow boundary from current upstream MCS, with this being a possible source for forced convergence across eastern upper Michigan this afternoon (if it can survive). Nothing widespread severe expected given weak wind fields aloft. If storms can form, locally heavy rain and some brief wet- microburst produced gusty winds are possible. Very warm today, with highs expected to top out in the upper 80s to lower 90s across inland areas south of the Might Mac. Expect readings to remain a touch cooler near the big waters and across eastern upper Michigan. && .SHORT TERM /THROUGH TONIGHT/... Issued at 351 AM EDT Mon Jun 17 2024 Pattern Synopsis and Forecast: Current satellite and radar shows a few isolated showers and storms moving into Canada from the upper penisula early this morning as they exit the CWA. Surface observations show moisture advection continuing from west to east, raising dew points into the mid to high 60s by mid day today. PW values of around 1.5" will exist today as deep moisture advection continues around an anchored upper level high pressure centered over the Carolinas. Upper level lows exist over central Canada and the US West, leading to strengthening southwest flow over the central plains and Great Lakes region today. Slight ridging extending from the upper high will rotate over the state today slightly increasing heights aloft. This combined with southwest winds near the surface (leading to downsloping in some locations) will result in temperatures warming around 5 to 15 degrees from yesterday (reaching into the low to mid 80s for eastern upper and high 80s to low 90s for northern lower). Model soundings depict an environment with ample instability and weak (but existent) speed shear through the column. With convective temps around 90, skies should start to fill in with CU & towering CU over northern lower in the afternoon hours. Southwest winds will likely work to keep the lake breezy away until the later afternoon hours (when winds are forecasted to weaken). Some CAM guidance depicts the lake breeze pushing inland near the tip of the mitt, which in theory should help kick up a few showers and thunderstorms in this environment. The main hazards with the few storms that do form will likely be heavy rain, small hail, and brief gusty winds. Chances for isolated showers and thunderstorms will linger through tonight. Primary Forecast Concerns/Key Messages: Lots of uncertainty still exists in the forecast today, as the CWA will likely have a high CAPE low shear environment with chaotic triggers for convective initiation. CAM soundings show around 2-3k j/kg of SBCAPE with mixing heights rising to around 4-5 kft around mid day. Convective temps are around the low to mid 90s for northern lower as well. All of this points to a likely scenario of skies filling in where convective temperatures can be reached. Afternoon temperatures will feel hot and muggy, however the hottest temperatures will not last that long due to the chances of shower and storm development in those areas. Some CAMs are not picking up on the diurnally driven convection as much, and need a trigger. The HRRR depicts the lake breeze moving over the northern areas of northern lower later this afternoon, which could be that trigger for showers and storms. To summarize, this afternoon will feel hot and humid (with some of the best chances for the hottest temperatures near Saginaw Bay). However, chances for afternoon storms will likely allow for quick relief to most areas in the form of rain, outflows, or clouds filling in the skies overhead. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Issued at 351 AM EDT Mon Jun 17 2024 Pattern Synopsis: Impressive ridging will grip most of the CONUS east of the Mississippi River through the duration of the workweek as troughing churns over the Pacific NW and northern Great Plains. To put this ridging in perspective, forecast 500mb heights of 594+ dam over a several day stretch would exceed climatological max values during that span based on a 30-year reanalysis period centered around the middle of June. Thus, the strength of aforementioned ridging in place heading into the weekend is rare. With surface high pressure centered over the Atlantic, the Great Lakes look to be caught between surface features into the middle of the week before high pressure may build in more firmly heading into the weekend. Forecast Details: Very hot, humid conditions -- The potential for very hot, humid weather is expected to persist across the Great Lakes trough the middle of the week, and perhaps through the end of the week as well. Aforementioned ridging/high pressure placement will keep Michigan in south/southwesterly low-level flow through Wednesday, allowing for warm,moist advection to continue with no major frontal passages. In turn, a very moist boundary layer characterized by dewpoints in the mid 60s to low 70s is expected to stick in place for at least several days. Combined with this will be the potential for high temperatures to climb into the low to mid 90s Tuesday and Wednesday, and mid 80s to low 90s beyond that this week. Furthermore, overnight lows staying in the upper 60s Monday night and low to mid 70s Tuesday night will offer little relief from the early week heat. The main caveat and source of uncertainty at this time continues to be the potential for convection/convective debris impacting high temperatures through the middle of the week, as the full potential of high temperatures may not be realized should storms form near/across the region during the afternoon hours. Chances for showers/storms at times this week -- As mentioned above, there will be chances for showers/storms at various times this week. However, pinpointing any precise timing and locations is highly uncertain at this time. Aforementioned moisture-rich boundary layer will lead to ample buoyancy to support thunderstorm chances most days -- especially during the afternoon and evening with peak heating. There is an expected lack of more defined forcing mechanisms to trigger convection across the region, but any subtle forcing may be enough to trigger pop-up storms at times through the duration of the work week. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 104 PM EDT Mon Jun 17 2024 Will need to watch for some late night mist and low cloud development at KCIU, as well as a few afternoon showers and storms at both KCIU and KAPN. Will continue to cover the latter with vicinity wording only as overall coverage looks to remain minimal. Otherwise, expecting VFR conditions to continue under passing high clouds and some relatively higher based cumulus. Somewhat gusty southwest winds this afternoon will go light tonight. Winds become gusty out of the south to southwest again Tuesday. && .APX WATCHES/WARNINGS/ADVISORIES... MI...Air Quality Alert until midnight EDT tonight for MIZ020-025- 026-031. MARINE...None. && $$ UPDATE...MSB SHORT TERM...ELD LONG TERM...DJC AVIATION...MSB