Area Forecast Discussion
Issued by NWS Gaylord, MI
Issued by NWS Gaylord, MI
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695 FXUS63 KAPX 050149 AFDAPX Area Forecast Discussion National Weather Service Gaylord MI 949 PM EDT Thu Jul 4 2024 .KEY MESSAGES... - Increasing rain threat...mainly late tonight and moreso into Friday. - Severe thunderstorm possibilities Friday? Day 2 SPC Marginal severe risk now encompassing most of northern Michigan. - Fluctuation temperatures with periodic shower chances through the extended. && .UPDATE... Issued at 949 PM EDT Thu Jul 4 2024 Vertically-stacked low pressure continues to develop over Minnesota late this evening...generating several areas of showers and thunderstorms currently impacting portions of Minnesota...Wisconsin and Iowa. Closer to home...spotty showers have tried to develop during the afternoon and early evening with limited luck due to dry low level northeasterly flow. Loss of diurnal heating/instability has brought any spotty shower activity to an end. However...still do expect low levels will gradually moisten overnight to allow upstream shower activity to make steady west to east progress into our CWA. Limited instability (MUCAPES of up to 500 J/kg) will lend to some embedded thunder...but weak wind fields will preclude any strong to severe storms overnight. Overnight lows will cool into the 50s across Eastern Upper Michigan and into the lower 60s across Northern Lower Michigan. && .SHORT TERM /THROUGH FRIDAY/... Issued at 331 PM EDT Thu Jul 4 2024 Pattern Synopsis/Forecast: Pretty disorganized (read: summertime) surface pattern across the Great Lakes and Midwest this afternoon. Broad area of low pressure over western Minnesota into western Iowa...main center probably along the state line where 2-3mb/3h pressure falls occurring. Warm front extends east across southern Minnesota into southern Wisconsin. Weak pressure gradient across the upper Lakes allowing for widespread lake breeze development this afternoon. This is occurring ahead of a short wave trough over the eastern Dakotas/Nebraska...with several embedded vorticity centers in water vapor imagery over southwest Minnesota and southern Wisconsin. High level overcast across northern Michigan at mid afternoon along with a scattered Cu field at least (hard to tell with the intervening Ci layer). Some nominal MLCAPE (~100-200J/kg) has developed along the southeast shore of Upper Michigan...right along the Lake Huron shore south of Thunder Bay...as well as west of the M- 37 corridor...due to onshore flow off the lakes and/or moisture pooling along the lake breeze (in the U.P. and northeast Lower case...where there are some hints of enhanced Cu on radar). The short wave trough moving through the northern/central Plains will arrive over the upper Lakes Friday morning along with its associated surface wave (~1005mb). These features will cross Michigan Friday/Friday night...probably with secondary cyclogenesis occurring over Lower Michigan Friday afternoon. Primary Forecast Concerns: Increasing rain threat...mainly late tonight and moreso into Friday: Aside from the wannabe showers trying to form near Saginaw Bay... upstream precipitation is concentrated around the short wave trough over the eastern Dakotas/southern Minnesota...as well as over central Wisconsin though that seems to be higher based. Current thinking is that the bulk of the measurable precipitation won`t arrive until after midnight. Passage of lead vorticity center over Wisconsin may bring some virga or very light rain/sprinkles this evening given relatively dry lower levels...but expect rain to expand/develop eastward Friday morning with arrival of better moisture/forcing. Rain will likely be more persistent the farther north you go on Friday...across central Lower Michigan potential is for more a more showery/convective nature (and perhaps heavier from a QPF standpoint) to the precipitation along the occluded boundary/ secondary cyclogenesis forecast to occur over central Lower Friday afternoon. Which leads to our next concern... Severe thunderstorm possibilities Friday? Day 2 SPC Marginal severe risk now encompassing most of northern Michigan: Greatest threat area for severe storms Friday probably more confined to northern Lower (maybe even south of M-32) closer to the occluded front and secondary cyclogenesis where better instability (perhaps getting close to 1000J/kg MLCAPE) and better deep layer shear will reside (strongest shear expected over southern Lower but forecast hodographs look pretty stretched out in our neck of the woods). && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... Issued at 331 PM EDT Thu Jul 4 2024 Pattern Synopsis/Pattern Forecast: Rather amplified upper level flow regime (especially for summer) set to further establish itself as we head through the weekend into early next week...featuring western NOAM heat dome/deep layer ridge axis upstream of broad Great Lakes centered troughing. Such a pattern supports no prolonged periods of heat and periodic shower chances across the Great Lakes region. Primary Forecast Concerns/Challenges: Shower potential and temperature trends through the entirety of the long term period. Details: Beyond Friday (see Friday`s details in the short term section above), the rest of the weekend shaping up to be rather uneventful. While departure of moisture rich primary shortwave Friday evening ends the most widespread rain potential, lingering troughiness does support at least some scattered light shower concerns through the day Saturday. Still, trends definitely support much of the time and most of the area remaining dry through Saturday, with any showers past Friday evening remaining fairly light and scattered. Kinda the same story for Sunday...although some support for a passing shortwave ridge during the morning in mid-range guidance may suppress moist convection even further. Again, cannot completely rule out an afternoon shower or storm...especially where lake breeze convergence axes are maximized. Weather potentially gets a bit more active yet again heading into next work week, with growing support for a rather robust shortwave trough to visit the region. Of course, overall strength, timing, and moisture availability all remain in question at this early juncture. Unfortunately, forecast will display this uncertainty by showing an extended duration of rain potential...when in all likelihood, the actual duration of better rain chances will fall int a much shorter time period. What transpires with the early week system (mainly speed and depth) will have a lot to say on how the remainder of the week unfolds. As mentioned earlier, long wave flow regime does not support any prolonged heat up here in the Northwoods. Expect temperatures to fall well within the range of what is considered normal for this time of year. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 700 PM EDT Thu Jul 4 2024 Broad area of surface low pressure will hold over Michigan tonight...before a sharp upper level trough axis swings into the Western Great Lakes region on Friday. Chances of showers and thunderstorms will steadily increase overnight thru Friday as this upper level trough arrives. Prevailing conditions will remain VFR for the next 24 hours...but may briefly drop to MVFR/IFR within any heavier showers/storms that develop later tonight thru Friday. Light/variable surface winds tonight will become easterly under 10 kts on Friday. && .APX WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ UPDATE...MLR SHORT TERM...JPB LONG TERM...MSB AVIATION...MLR