Area Forecast Discussion
Issued by NWS Gaylord, MI
Issued by NWS Gaylord, MI
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744 FXUS63 KAPX 241740 AFDAPX Area Forecast Discussion National Weather Service Gaylord MI 140 PM EDT Tue Sep 24 2024 .KEY MESSAGES... - A bit dreary and damp today/tonight - Quieter weather for the rest of the week into the weekend && .UPDATE... Issued at 1047 AM EDT Tue Sep 24 2024 Broad troughing overtaking the central US and Upper Midwest today...as ridging moves into the PacNW. 120+kt upper jet feeding into sharp shortwave troughing digging into the central Plains...with a swirly spinning up over western MN/eastern Nebraska. Attendant surface occluded system with this stretches from western MN back into the central Plains. Meanwhile...on the downstream side of this sharp shortwave trough...niblet within the flow lifting NNE- ward through central WI into northern MI...with subtle ridging aloft between this and the next bit of energy over IL...where surface low is located; cold front with this stretches down into TX along deformation axis, and warm front stretches eastward through the OH Valley into the Carolinas. Anomalous moisture focused along this boundary...with some northward moisture advection into the Upper Great Lakes on SSW flow aloft. Broad easterly low-level flow over the region this morning; some subtle hints of departing surface troughing over Lake Huron between this and incoming surface low and inverted trough stretching up along the WI coast...with a couple more distinct areas of precip/convective precip over Saginaw Bay and west central MI, respectively. Drizzle and low stratus/fog present over interior northern Lower thanks to easterly upslope flow and moisture advection; ceilings less than 1000ft in most cases with visibilities less than 1SM over interior northern Lower and also along the Lake Huron coast due to subtle lake influences. A little bit of subtle clearing/breaking up of the stratus deck over NW Lower into parts of the EUP with the weak upper ridge oozing in. Expecting rain to continue to track NE/NNE-ward through the region today...though have some concerns the best moisture and forcing could remain to our southeast...so will keep an eye on this going forward. && .SHORT TERM /THROUGH TONIGHT/... Issued at 333 AM EDT Tue Sep 24 2024 Pattern/synopsis: Weak low pressure is near STL. This low will deepen somewhat as it lifts slowly ne, reaching central lower MI tonight. The low is forced in part by a shortwave trof moving east across Superior late tonight, and in part by a closed 500mb low crossing MO. The dominant big-picture trend is for a somewhat deeper, and somewhat slower, system. Forecast: Easterly flow off of Lk Huron is generating lake effect clouds (MVFR) into ne lower MI. OSC briefly reported precip (DZ) earlier in the morning. Area radars are showing an area of bubbly mid-level returns from w central lower MI to ne WI. Most of this is likely not reaching ground, but a few spots could be. As the surface low moves toward AZO by dusk, and a warm front also lifts into far southern lower MI. Though the deepest moisture/best forcing remains just downstate, plenty leaks into northern MI as the day proceeds. And that further interacts with overlake instability, with 850mb temps around 10-11C over Lake Huron. There is more of a southerly component to the 1000-850mb winds, and the longest fetch from Lk Huron into eastern upper MI for much of the day. MlCape values are quite limited, but values of 100-200j/kg are possible in ne lower MI. Pops will tend to increase from se to nw with time today. Pops are higher downwind of Lk Huron, including eastern upper MI, even though that is further north than better moisture fields. Sct to numerous showers are progged for much of today and tonight in ne lower/eastern upper MI, starting to diminish very late tonight. Precip could and probably will switch nature, from showery to drizzly and back again. There is also a slight chance for thunder in ne lower MI. Further, 850-700mb deformation/stretching on the north side of the approaching surface low is certainly present. That could contribute to localized healthy rainfall rates. This is particularly the case this evening, with localized QPF in excess of 0.25" in se portions of the forecast area. Max temps today in the 60s to around 70f. Lows tonight in the 50s. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Issued at 333 AM EDT Tue Sep 24 2024 Pattern Synopsis and Forecast: Midlevel split flow pattern continues to occupy North America. Southern stream flow currently influencing the Great Lakes region will continue to push warmer than average temperatures for the long term period. Current troughing over the Mid-Mississippi Valley pass through the Great Lakes region. Shortwave ridging builds this Wednesday and beyond. This pattern supports surface high pressure to occupy the CWA for the majority of the long term, resulting in quiet weather and above average temperatures for late September. Primary Forecast Concerns/Key Messages: No impactful weather expected throughout the entirety of the long term forecast period: Conditions are expected to remain quiet and dry for the majority of the period. After a few lingering showers finally diminish, surface high pressure will begin to build this Wednesday. This patten supports clearing skies with highs in the low to mid 70s for the next several days and lasting through the remainder of the forecast period. Only chances of precipitation is later next week as ensembles hint at an additional trough moving into the Ohio Valley around the Sunday/Monday timeframe. Guidance continues to struggle with a solution next week most likely due to discrepancies in the exact track of the ruminants of what will be Hurricane Helene. Confidence along with messaging will remain low at this time until future ensembles have a more detailed solution. Until then, little if any precip is expected to persist though the entirety of the long term. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 139 PM EDT Tue Sep 24 2024 N-S oriented trough axis over Lake MI this afternoon...with developing surface low over IL...to track northeastward into the Thumb of MI and Lake Huron overnight. Expecting a moisture axis to linger over NW Lower (TVC/MBL...PLN?) this evening into the overnight (through about 8-10z), and expect IFR to LIFR cigs/visbys...though not impossible this axis hangs up a little further east. Elsewhere...TS possible for APN between 0-9z with any rain. Generally, IFR to LIFR cigs expected through the night, with slow improvement from west to east after daybreak Wednesday. Surface winds generally at or below 10kts with an easterly component, ultimately becoming northwesterly by morning (quickest at TVC, MBL). Not impossible to get some gusts around 15kts at times this afternoon where some breaks in the clouds form. && .APX WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ UPDATE...FEF SHORT TERM...JZ LONG TERM...SJC AVIATION...FEF