Merry month of May

Merry month of May

springI my opinion May is the nicest of the spring months and on average along with September are the best months weather wise in west Michigan (September is the better of the two IMO) May like the other spring months can have big day to day and year to year swings in both precipitation and temperatures. For example, the hottest day in May was a very hot 95° on May 31st 1934 to a crisp cold low of 21° on May 1st 1903. The average high starts out at 65° and works its way up to 74° by the end of the months and the average low starts out at 43° and is up to 53° by the end. The mean temperature for May at Grand Rapids is 58.7° the warmest mean temperature for May was 65.7° in 1977 and the coldest mean temperature for May was twenty years later with a cool 50.3° in 1997. (the average mean for April is 48.3° so 1997 was a cold May) The average amount of precipitation for May is 3.98” with the most 10.01” falling in 2001 and the driest May was in 1936 when only 0.72” fell. On average May receives less than a trace of snow but in May of 1923 Grand Rapids (and much of lower Michigan) had a true snowstorm and here in Grand Rapids we recorded a almost unbelievable 5.5” of snow. All 5.5″ falling on May 9th 1923 (some other snow fall reports for May 9th 1923 Flint 12” Lansing 11.5” Saginaw 9” Muskegon 5”) In May of 1902 grand Rapids also had 5.5” of snow. That year the snow fell on May 10th In 1929 Grand Rapids had 3.0” of snow in May in that year the May snow storm was on May 2nd The last time Grand Rapids had over one inch of snow in May happened in 1954 when 2.0” of snow fell. In May of 1954 the snow fell on May 3, 4 and 5th the last year where GR had more than a trace of snow was in 1990 when 0.2” fell on May 10th The most sun shine for May happened in 1958 with 84.5% and in May of 1973 Grand Rapids had a November like total sun shine amount of only 28.2% the highest reported wind gust for May happened on May 5th 1950 with a reported gust of 79 MPH. Last year in Grand Rapids the mean May temperature was 60.4° (+1.7°) the warmest day was 88° on the 25th Grand Rapids ended the month with 11 mid summer like days in a row with the last 9 in the low to upper 80’s.  and the coldest low was 36° on the 15th. Grand Rapids had 3.01″ of rain,
Some past weather events for May in the state of Michigan
1896 May 25th 5 powerful tornadoes march eastward across Tuscola, Genesee, and Oakland counties the most powerful one leaves 47 dead in its half wide 30 mile long track it was estimated (not sure by who) that the winds exceeded 260 Mph
1917 Marquette’s harbor is closed due to ice until May 17th
1923 May 9th snowstorm with up to a foot of snow falling at Flint and just under a foot at Lansing may areas in lower Michigan seen 5+ inches of snow on this date.
1929 Another snowy May with 2.5” at Gull Lake and 13” at Atlanta (west of Alpena)
1952 A powerful Northwest wind floods parts of Sault St Marie on May 5th
1953 another powerful storm hits Lake Superior with winds of over 60 MPH on May 11th sending the freighter Henry Steinbrenner to the bottom of the lake with all of her 17-man crew.
1956 At 5:06 AM May 13 the tip of a funnel cloud reportedly passes less than 100 feet above the National weather bureau office at Muskegon.
1964 Severe weather is reported over much of lower Michigan on May 8th with the worst being a tornado that strikes Mt Clemens killing 11 and destroying 132 homes.
1966 an May cold snap sends the temperature down to bone chilling +8 at Vanderbilt.
1970 Several powerful thunder storms rocks the Detroit area for several hours on May 22-23 starting several fires including one at the Crucible Steel Co that has gone down as Michigan most damaging lightning strike
1980 May 13th a tornado rips through the Kalamazoo leaving 5 dead and destroying or damaging around 1000 buildings. Another tornado hit Van Buren county with over 700 more building either destroyed or damaged. And yet another storm system brought more tornadoes and high winds to Southwest Michigan on May 30th with winds reaching a reported 115 at St Joseph.
1983 On May 2nd a tornado touches down in Detroit and damages dozens of homes, several boats and a airplane hangar.


The Flood Watch continues for

* Portions of central Michigan, south central Michigan, southwest Michigan, and west central Michigan, including the following areas, in central Michigan, Gratiot, Isabella, Mecosta, and Montcalm. In south central Michigan, Clinton, Eaton, and Ionia. In southwest Michigan, Allegan, Barry, Kalamazoo, Kent, Ottawa, and Van Buren. In west central Michigan, Muskegon, Newaygo, and Oceana.

* From 2 PM EDT this afternoon through Monday morning

* Periods of rain this afternoon through Monday morning could result in rainfall totals of 2-4 inches. Locally higher amounts cannot be ruled out in or near thunderstorm development.

* At this point it seems the heaviest rainfall will be tonight and then Sunday afternoon into early Monday morning.

Forecast Maps

HRRR and Futurecast models runs are for 18 hours beginning at 7am – a second model run begins at 3pm


Day and Week Planner

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Temperature and Precipitation Forecasts

Point Forecasts


Forecast Discussion

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Grand Rapids
Grand Rapids

LI (Lift Index)
LI (Lift Index)
Rainfall Forecast
Wind Gusts
Wind Gusts

The threat of heavy rainfall is our primary story for this weekend. We have a storm coming northeast out of the southern Plains that runs into a large Canadian Polar High over Ontario. That blocks front front from getting to far north and results an extended period of showers and thunderstorms from late this afternoon into Monday morning.

Rainfalls of over 2 inches are more than possible over a large part of our area by Monday morning. It will be cooler than normal through the weekend thanks to that blocking Canadian high. The cold front comes through early Monday but we remain in the systems cold air and wrap around showers into Tuesday afternoon.


The primary issue will be the heavy rain threat from late this afternoon into around mid morning Monday. I continued the areal flood watch from 2 pm today till 8 am Monday as nothing as changed from what I can see in the models (we have been watching this for over a week now).

The heaviest rain is expected during two time periods, tonight and late Sunday into the early morning hours of Monday. The axis of heaviest rainfall seems to be near US-131 south to north give or take 50 miles. This is a classic case of a blocking Canadian high stalling the warm front near or just south of I-94 tonight into Sunday. That result in the moisture feed being pinned in largely the same location. We have all the classic signatures for heavy rain, the model sounds are saturated from near the surface to 200 mb tonight into Sunday night. The cape is narrow but deep so we do not get very strong thunderstorms, just heavy rainfall. The precipitable water (between 1.5 inches and 1.8 inches on Sunday) is shown by the Western Region Ensemble Situational Awareness table to be 3 standard deviations from normal with a return period at this time of year at less than 1 day in 30 years.

We also have a 40 to 60 knot low level jet crossing the warm front tonight then again later Sunday into early Monday ahead of the cold front (occluded front). There also remains excellent model continuity and now the high res models like the HRRRX go out far enough and also support the idea of heavy rain tonight into Monday Morning.

So bottom line….we will see periods of showers and thunderstorms this evening into early Monday morning. We get into the cold air wrap around showers Monday but there will likely be a dry slot so we may get 6 hours of dry weather once the front comes through before the showers move back in from the upper cold pool instability. .


The weather during the long term will be front-loaded; rain is expected Monday night and then diminishing Tuesday with dry weather late Tuesday through Friday. The deep upper low responsible for producing heavy rain across the cwa this weekend will be over Michigan late Monday.

Showers seem likely Monday night as the low moves through and several short wave rotate through the flow. Skies will begin to clear Tuesday afternoon as the low moves northeast into Canada. Another trough will approach Wednesday night, but that is really supporting a low over the Tennessee Valley.

The ecmwf is a bit farther north than the gfs and would give us some light rain over the eastern cwa Thursday afternoon, but the gfs wold keep us dry. Given that both models seem to be transition the upper pattern to a cutoff low over the deep south, we`ll lean toward the drier gfs solution. Chilly temps are expected through the period. Highs in the 50s are expected Tuesday-Thursday before climbing to around 60 Friday.

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Sandy (Hudsonville)

Great post SlimJim. It has been raining here pretty hard this evening. I am sure there will be flooding in the area by Monday morning especially low areas.