Cool air aloft contributed to shower and thunderstorm development. A few of these storms produced gusty winds.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS APX wrote it up.
Cool air aloft contributed to shower and thunderstorm development. A few of these storms produced gusty winds.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Gaylord, MI wrote its last area forecast discussion before the first event at Aug 17, 1:39 PM EST, 1 minute earlier.
Area Forecast Discussion National Weather Service Gaylord MI 239 PM EDT Mon Aug 17 2020 .UPDATE... Issued at 1145 AM EDT Mon Aug 17 2020 Morning analysis reveals a large scale ridge/trough pattern across the CONUS anchored by a strong 600+ DM upper level high over Nevada/Utah. Subsequent deepening troughiness taking shape across eastern Canada into the Great Lakes/New England with fairly cool air diving into the region (core of +1C 850 MB air is lurking across northern and central Ontario). Upper jet core stretches from western Ontario down through western Lower Michigan. A couple of short-wave features of note along the cold side of the upper jet; one moving through eastern Ontario and second smaller feature diving southward across Lake Superior. Radar has been clear for the last hour or two. But, there is a small shower that has developed in Antrim county recently, within the developing Cu field across parts of northwest Lower MI and tip of the mitt. Shapes of things to come I suppose. 12Z APX sounding revealing that ongoing cooling aloft with 700 MB temps down a few degrees C since last evening and already some SBCAPE out there early this morning. Continued cooling aloft through the afternoon in concert with daytime heating and some modest larger scale forcing via the aforementioned short- wave...should lead to shower and thunderstorm development through the afternoon. Overall NW flow and enhanced convergence across NE Lower Michigan still suggests the best shower/thunderstorm chances will be across that area and down toward Saginaw Bay, where RAP13 forecast soundings depict a few to several hundred J/Kg MLCAPE this afternoon...although I have expanded Pops back westward just a bit as well. Severe weather threat: Stronger mid level flow and increased 0-6Km shear values increase to around 30 to 40 knots this afternoon, especially across the E/SE part of the CWA. Along with freezing levels falling below 10K feet and a decent amount of DCAPE, and localized enhanced low level vorticity along the Huron coast... beginning to think we may be issuing a few severe thunderstorm warnings this afternoon although we are still just in general thunder in SPCs day one outlook. As a final note, given the ongoing cooling aloft and possibilities for convection moving out into Lake Huron, I've added waterspouts to the nearshore zones on Lake Huron. Already seen some reports of waterspouts near Georgian Bay this morning. && .NEAR TERM...(Today through Tonight) Issued at 331 AM EDT Mon Aug 17 2020 ...Small chances of showers today for some areas... High Impact Weather Potential...None. Pattern Synopsis/Forecast...Broad upper level troughing remains over the Great Lakes region early this morning. Weak short waves continue to ripple thru the upper level trough...generating spotty showers and a few embedded hits of thunder. Current short wave over our area is focusing convective activity across portions of Central and Southern Lake Michigan and Southern Lower Michigan...with our next short wave now moving thru Lake Superior where an area of showers has developed. Closer to home...wx is mainly dry and partly to mostly clear attm in between these two waves. As we head into today...a few showers via the Lake Superior wave will clip portions of Eastern Upper and far Northeast Lower Michigan early this morning. Wave will then push southward into Northern Lower Michigan by this afternoon. Lift via this feature combined with building diurnal instability will kick off some scattered showers across portions of NE Lower Michigan this afternoon and early evening. Wave will then push east of our area later this evening...bringing an end to precip chances for the rest of the night. Skies will clear as low level ridging builds into the region. Expect a very pleasant mid August day across the Northwoods...with afternoon highs warming into the 70s everywhere. Low temps tonight will cool mainly into the upper 40s and lower 50s. && .SHORT TERM...(Tuesday through Wednesday) Issued at 331 AM EDT Mon Aug 17 2020 ...A Little Cool Tuesday, Warmer Wednesday... High Impact Weather...None is expected. Forecast Concerns...Pops late Tuesday night into Wednesday. An impressive looking upper level ridge will continue to sizzle the southwestern states while an upper level trough remains centered across northeastern Canada into the Great Lakes. This setup results in northwest upper level flow across Michigan. Meanwhile, surface high pressure is expected to keep northern Michigan rain free into Tuesday night. A possible short wave moving through the flow will then bring small chances for showers Wednesday. Temperatures will only range from the upper 60s to mid 70s Tuesday but then warm into the mid and upper 70s Wednesday. Lows Tuesday night are expected to be rather cool with the 40s to around 50 expected forecast area wide. .LONG TERM...(Wednesday night through Sunday) Issued at 331 AM EDT Mon Aug 17 2020 ...Warmer with Sporadic Shower Chances... High Impact Weather...None is expected at this time. The upper level flow over northern Michigan morphs from troughy to nearly zonal. Although the extended forecast will include various slight to low chances of showers and possible storms due to weak short waves moving through the flow, no prolonged periods of rain are anticipated. Temperatures are expected to warm to above normal levels later in the week. The blend then has cooler temperatures moving in for this weekend but that may turn out to be overdone. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) Issued at 239 PM EDT Mon Aug 17 2020 Showers and a few thunderstorms will be found across northern Lower Michigan this afternoon...primarily impacting the APN terminal site. These end this evening with overall quiet conditions again tonight. Might see a few more showers pop-up across NE Lower Michigan on Tuesday, again impacting APN. Otherwise, VFR weather dominates through Tuesday. Patchy fog is possible again tonight, but don't have that explicitly in the TAF forecast at this point. NW gustiness this afternoon into the evening, with some gusts of 20 to 25 knots. && .MARINE... Issued at 331 AM EDT Mon Aug 17 2020 Winds and waves will reach SCA criteria today into tonight for some of our nearshore areas as NW winds increase to 15 to 25 kts. Some areas will see a few showers...with the best chances mainly during this afternoon into early evening within our Lake Huron nearshore areas. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...SMALL CRAFT ADVISORY until 6 AM EDT Tuesday for LHZ346>348. LM...SMALL CRAFT ADVISORY until 6 AM EDT Tuesday for LMZ342-344. LS...SMALL CRAFT ADVISORY until 6 AM EDT Tuesday for LSZ321-322. && UPDATE...BA NEAR TERM...MR SHORT TERM...AS LONG TERM...AS AVIATION...BA MARINE...MR
Hazardous Weather Outlook National Weather Service Gaylord MI 1013 AM EDT Mon Aug 17 2020 MIZ016>018-020>036-041-042-086>088-095>099-181000- Emmet-Cheboygan-Presque Isle-Leelanau-Antrim-Otsego-Montmorency- Alpena-Benzie-Grand Traverse-Kalkaska-Crawford-Oscoda-Alcona- Manistee-Wexford-Missaukee-Roscommon-Ogemaw-Iosco-Gladwin-Arenac- Western Chippewa-Central Chippewa-Southeast Chippewa- Western Mackinac-Eastern Mackinac- Mackinac Island/Bois Blanc Island- Beaver Island and surrounding islands-Charlevoix- 1013 AM EDT Mon Aug 17 2020 This hazardous weather outlook is for Eastern Upper Michigan and Northern Lower Michigan. .DAY ONE...This afternoon and tonight. There is chance of thunderstorms this afternoon and early evening across portions of Northeast Lower Michigan. Severe storms are not expected. However, any storms could produce gusty winds and small hail. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. There are mainly small chances for thunderstorms across parts of the outlook area Friday through Sunday. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated. && For more information visit http://weather.gov/gaylord. LHZ345>349-LMZ323-341-342-344>346-LSZ321-322-181000- Straits of Mackinac within 5 nm of Mackinac Bridge including Mackinac Island-St Ignace to False Detour Channel- 5NM East of Mackinac Bridge to Presque Isle Light MI including Bois Blanc Island- Presque Isle Light to Sturgeon Pt MI Including Thunder Bay National Marine Sanctuary-Sturgeon Pt to Alabaster MI- Grand Traverse Bay south of a line Grand Traverse Light to Norwood MI-Seul Choix Point to 5NM West of Mackinac Bridge- Norwood MI to 5NM West of Mackinac Bridge including Little Traverse Bay-Sleeping Bear Point to Grand Traverse Light MI- Point Betsie to Sleeping Bear Point MI- Manistee to Point Betsie MI- Whitefish Bay (U.S. Portion)/Whitefish Point to Point Iroquois MI- St. Marys River Point Iroquois to E. Potagannissing Bay- 1013 AM EDT Mon Aug 17 2020 This hazardous weather outlook is for the northern Michigan nearshore waters of Lake Huron, Lake Michigan and Lake Superior. .DAY ONE...This afternoon and tonight. There is a chance of thunderstorms this afternoon and early evening across portions of northern and central Lake Huron. Severe storms are not expected. However, any storms could produce gusty winds, small hail and waterspouts. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. There are mainly small chances for thunderstorms across parts of the outlook area Friday through Sunday. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated. && For more information visit http://weather.gov/gaylord.
Special Weather Statement
National Weather Service Gaylord MI
119 PM EDT Mon Aug 17 2020
MIZ024-171815-
Alpena-
119 PM EDT Mon Aug 17 2020
...A STRONG THUNDERSTORM WILL AFFECT WESTERN ALPENA COUNTY...
At 118 PM EDT, a strong thunderstorm was located over Long Rapids, or
near Lachine, moving southeast at 20 mph.
Winds in excess of 30 mph and pea size hail are possible with this
storm.
Locations impacted include...
Alpena, Ossineke, Lachine, Long Rapids, Ossineke Township, Spratt,
Cathro and Devils Lake.
LAT...LON 4502 8337 4502 8338 4498 8336 4495 8338
4495 8332 4488 8371 4513 8388 4521 8374
4521 8363 4501 8331
TIME...MOT...LOC 1718Z 320DEG 19KT 4513 8372
STJSpecial Weather Statement
National Weather Service Gaylord MI
230 PM EDT Mon Aug 17 2020
MIZ030-171900-
Alcona-
230 PM EDT Mon Aug 17 2020
...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN ALCONA COUNTY...
At 229 PM EDT, a strong thunderstorm was located near Black River, or
7 miles north of Harrisville, moving southeast at 40 mph.
Winds in excess of 30 mph and half inch hail are possible with this
storm.
Locations impacted include...
Harrisville, Lincoln, Spruce, Black River, Harrisville State Park,
Lost Lake Woods, Hubbard Lake and Negwegon State Park.
LAT...LON 4468 8323 4464 8328 4463 8353 4482 8362
4486 8344 4486 8333 4488 8331 4488 8333
4489 8330 4484 8323 4475 8325 4471 8322
TIME...MOT...LOC 1829Z 315DEG 34KT 4477 8332
STJThe NCL Michigan radar (KAPX), 116 km away, was scanning. The volume nearest the first event began at 18:40 UTC.
1 marine thunderstorm wind. Local standard time, as filed.
A 43 mph wind gust was measured at Sturgeon Point Light.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Lake Huron in 2020Every state in 2020This day in weather history
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 918895.