The Storm Prediction Center has reduced the severe weather threat over much of West Michigan from Slight Risk to Marginal Risk. There is still a Slight Risk north of a line from Whitehall to White Cloud to Oscoda. SPC still says: “combination of forcing for ascent, favorable vertical shear, and ample low-level moisture will support organized thunderstorm development. Primary threat will be strong wind gusts with some hail also possible. A tornado or two is possible, particularly if areas of enhanced southerly surface wind develop.
Here’s the full SPC discussion. Here’s a morning update from the GRR NWS: “THE WARM FRONT- MID LEVEL MOISTURE WILL RUN INTO HIGHER INSTABILITY DUE TO DAY TIME HEATING, SO, I STILL THINK SCATTERED LATE MORNING INTO MID AFTERNOON THUNDERSTORMS ARE POSSIBLE NEAR I-69. THE OVERALL SEVERE THREAT TONIGHT REMAINS THE SAME, NORTH OF A LINE FROM MUSKEGON TO ALMA.”
Here’s storm reports from Monday…four tornadoes reported – 3 in N. Dakota and 1 in Nebraska. There were 45 reports of wind damage and 38 reports of severe criteria hail. The biggest hail reported was 2 1/4″ in diameter at Hisega SD and the fastest wind recorded was 78 mph in Nelson Co. ND.
This interesting map shows the average number of tornadoes by state during the month of July. Minnesota is #1 with 11 and N. Dakota and Colorado are #2 with ten. Note that Oklahoma averages only one – their tornado season is spring. Tennessee averages less than one tornado every 2 years in July. Michigan averages 3 – most are small and short-lived. Our biggest tornadoes (Flint/Beecher in ’53, Standale/Hudsonville in ’56, Palm Sunday in ’65, Grand Rapids in ’67, Kalamazoo in ’80 have come in April – early June – in the spring season).