Area Forecast Discussion
Issued by NWS Gaylord, MI
Issued by NWS Gaylord, MI
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981 FXUS63 KAPX 222014 AFDAPX Area Forecast Discussion National Weather Service Gaylord MI 414 PM EDT Sat Jun 22 2024 .KEY MESSAGES... - Heavy rain threat continues into the night. - Strong to severe storms remain possible into the evening. - Near seasonal temperatures with periodic shower and thunderstorm chances next week. && .SHORT TERM /THROUGH SUNDAY/... Issued at 411 PM EDT Sat Jun 22 2024 PATTERN SYNOPSIS/FORECAST: PV maxima shoving its way through WI...with surface low centered just SW of GRB at 18z. Complex boundaries across the area...with a warm/stationary front wrapping from the surface low over the Door and Leelanau Peninsulas and draping down into the Saginaw Bay region. Subtle surface convergence from TC to near Lake City...and another potential wind shift from near GRB toward LDM. 40+kt LLJ not entirely perpendicular to the strengthening boundary...but enough for some continued theta-e advection, particularly with swath of SW- NE oriented nearly 2" pwats aligning with the LLJ. Dry slotting developing on the SW corridor of the surface low over central WI...with some signals of more cellular/surface-based development there amid better convective instability. Broad area of generally stratiform rain moving overhead attm...though slightly more convective signals developing in spots, particularly in the vicinity of that convergence zone within the warm sector. Upstream PV niblet and its attendant dry slotting over WI expected to move into the area this evening/tonight...dragging a cold front into the region behind the surface low expected to trek across northern Lower (likely the Tip of the Mitt) tonight. Continued efficient rain expected with this; severe weather still remains a possibility into at least the evening with decent deep layer shear and potential for better instability hanging on into at least part of the night. Expecting cooling and drying behind the cold front into Sunday morning from NW-SE...with slightly gusty northwesterly winds developing on the back of the system. Think we will get some wrap around nonsense over NE Lower and the EUP Sunday afternoon as another wave drops in...which could generate a few more showers or even storms, though these may not be very robust either. Primary Forecast Concerns: Heavy rain threat continues into tonight...Think the heavy rain threat will hang on over the M-32 corridor and south through the evening...actually, through the bulk of the period, as the next batch of forcing moves in with the pv max tonight...focusing things more over NE Lower and points toward M-55/Saginaw Bay. A lot of uncertainty in the placement of bullseyes, but still not out of the question that some areas could see a localized additional 1-2" of rain overnight given the environment and additional forcing expected to drive through. Still some concern for either a northern shift in the bullseyes tonight, and/or a secondary QPF max over the EUP/Tip of the Mitt tonight into Sunday morning with the surface low driving through...particularly noting some signals in guidance for the surface low to track across the Tip of the Mitt. Do not have high confidence in the QPF forecast that`s going out, as it effectively shows signals for where the higher totals could be...but just low confidence in placement...as well as potential for much higher amounts than currently forecast. Additionally concerned that we may have to watch for subtle areas of training convection. Severe threat continues...Cohorts in the office attm watching some embedded spinnies along a subtle convergence boundary down near central Lower...which was one of the concerns mentioned in the AM update: that embedded spin-ups in the atmosphere may just end up being the primary severe concern. Not sure that much in the way of wind will get to the surface this afternoon/tonight over our region, apart from any downbursts with stronger convection toward Saginaw Bay where there is a better shot at mixing things down to the surface. Think this idea will hang on through the afternoon. May have to watch areas back toward NW Lower (CAD to MBL) as clouds attempt to break up in the wake of the convection with some dry slotting slipping in ahead of the PV max. While there could be some downward momentum transfer...soundings suggest we`ll have a strong inversion in place around 800mb which could keep winds from becoming too much of a problem...though suppose some hail threat may develop if storms end up getting elevated like this. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... Issued at 411 PM EDT Sat Jun 22 2024 Pattern Synopsis/Pattern Forecast: Large scale flow regime completely unlocks this week, with full retrogression of sub-tropical ridge axis into the Desert Southwest and penetration of northern stream flow into the northern Conus and Great Lakes region. This sets the stage for more seasonable temperatures and periodic shower and thunderstorm chances across northern Michigan. Primary Forecast Concerns/Challenges: Temperatures trends and addressing additional shower and thunderstorm concerns through next week. Details: As mentioned above, much more northern stream influences into the Great Lakes region next week. Several shortwave troughs set to crest western ridge and drop southeast into the region, each accompanied by what appears to be appreciable forcing and a decent pre-frontal moisture environment. While still some subtle timing differences with these waves (definitely to be expected in such an aggressive flow regime), decent agreement amongst all mid-range guidance that first such wave arrives during the Monday night-Tuesday period. Much too early to get into any specifics regarding storm potential, but what looks to be decent deep layer shear and respectable moisture profiles through the vertical does at least raise an eyebrow to brief heavy rain and severe concerns. Will continue to monitor of course. More energy set to arrive the latter portion of the week, again supporting more shower and storm potential. Multi-period mention of rain chances through the extended centers on the remaining timing uncertainty of these passing waves. Actual rain chances will likely be relegated to a much shorter time window...with those specifics working themselves out as we head further into next week. Definitely not seeing any evidence of prolonged heat in such a pattern. Temperatures will vary of course based off frontal passages, but overall flavor to temperatures should be well within the range of what is considered normal for this time of year. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 147 PM EDT Sat Jun 22 2024 Stationary boundary stretching from CVX to APN this afternoon. For now...expecting this to stay relatively stationary, but may lift further north. Anticipate a wind shift along the boundary, with sites north of this from ENE and areas south of this from SW (esp TVC, MBL) to SE (APN)...backing to N/NW late tonight for CIU and possibly PLN...and veering to SW/NW for the remainder of the sites behind a surface low pressure center. 30+kt LLJ aloft at or above 2kft will struggle to make it to the surface, but not impossible, esp toward MBL this afternoon. Better threat of mixing down winds is Sunday AM (outside of storms, which could pull stronger winds down). Cigs/vsbys largely IFR to LIFR, but could go MVFR toward MBL this afternoon for a time...with +RA a concern along with BR. TS/VCTS a possibility, esp south of a TVC to APN line, pending whether the boundary shifts further northward today, which could focus the heavier rain further north. && .APX WATCHES/WARNINGS/ADVISORIES... MI...Flood Watch through Sunday morning for MIZ016>018-020>036-041- 042-099. MARINE...None. && $$ SHORT TERM...FEF LONG TERM...MSB AVIATION...FEF