Earlier this week there were two events that could be classified as a derecho. Both were just west and south of the Grand Rapids area. We did get a a good Thunderstorm and a lot of rain from the 1st one and less lightning are less rain from the 2nd one.
Here is some information on derechos in general. Derechos can cause extensive damage, with wind speeds rivaling some tornadoes
In the Midwest summer is full of all sorts of weather events, but few pack as much destructive power. A derecho can cause wind speeds of over 100MPH. Damage can be almost as severe as a tornado. And they cover a much larger area than a tornado. According to NWS data, derechos are most common between May and July, when nearly two-thirds of the events have historically occurred. Derechos develop with a “bow echo.” Thunderstorms experience a phenomenon called “updrafts” early in their formation, when warm surface air rises until condensation begins forming, ultimately transitioning to rain. This forces cool air toward the ground on the back end of a storm, which has the effect of generating strong winds near the ground. As the line of storms strengthens, updrafts continue on the edge of the storm and the mass of rain-cooled air at the surface expands the storm horizontally, pushing it forward more quickly and generating higher wind speeds. In certain instances, those winds sustain for hundreds of miles.
Derechos can and have happened Michigan here are 3 of the bigger ones in Michigan.
July 16, 1980: This derecho moved through extreme Southern Michigan.
July 13, 1995: This derecho moved across Upper Michigan and Lower Michigan, causing millions of dollars in damage, three deaths, and several injuries. In Roscommon County alone, 100,000 trees and 100 miles of power lines were blown down.
May 31, 1998: This derecho hit West Michigan, causing an average speed of 70 mph and winds of up to 130 mph. The storm killed four people, injured 146, and caused an estimated $172 million in damage. The Federal Emergency Managers Association declared 13 counties a Federal Disaster Area.
The official H/L yesterday at Grand Rapids was 80/53 there was no rainfall the highest wind guest was 19 MPH out of the NW. The sun was out 91% of the possible time. For today the average H/L is 83/63 the record high of 99 was set in 1930 and 1934 the coldest high of 63 was set in 1912. The record low of 44 was set in 1941 the warmest low of 75 was set in 1991,1975 and 1926. The record rainfall of 2.78” fell on that cool day in 1912.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
328 AM EDT SAT JUL 20 2024
KEY MESSAGES
- HUMIDITY RETURNS, CHANCE OF STORMS NORTH SUNDAY
- QUIET WEATHER THROUGH MONDAY, THEN RAIN CHANCES RETURN
DISCUSSION
ISSUED AT 328 AM EDT SAT JUL 20 2024
- HUMIDITY RETURNS, CHANCE OF STORMS NORTH SUNDAY
HIGH PRESSURE OVER THE GREAT LAKES WILL BEGIN TO DRIFT EAST TODAY
RESULTING IN A SOUTHERLY FLOW DEVELOPING. DEWPOINTS WILL INCREASE
AND SO WILL THE HUMIDITY. HIGHS AROUND 80 AND DEWPOINTS AROUND 60
ARE PRETTY TYPICAL OF SUMMER AND THAT'S WHAT WE'LL HAVE TODAY,
ALONG WITH MOSTLY SUNNY SKIES.
ANOTHER MOSTLY CLEAR SKY TONIGHT WILL SEND TEMPERATURES DOWN TO
AROUND 60. THE HIGHER DEWPOINTS MAY RESULT IN SOME PATCHY FOG
OVERNIGHT.
A DEEPER UPPER TROUGH OVER JAMES BAY WILL PUSH A WEAK COLD FRONT
SOUTH ACROSS LOWER MI SUNDAY. THE CONVERGENCE ALONG THE FRONTAL
BOUNDARY COUPLED WITH THE HIGHER DEWPOINTS AND SBCAPE AROUND 900
J/KG AND LI'S AROUND -6C MAY RESULT IN SCATTERED CONVECTION
DEVELOPING OVER THE NORTHERN HALF OF THE CWA SUNDAY AFTERNOON.
GIVEN SHEAR VALUES LESS THAN 20 KTS, NO SEVERE WX IS EXPECTED.
- QUIET WEATHER THROUGH MONDAY, THEN RAIN CHANCES RETURN
FLOW REGIME ACROSS THE CONUS IS DOMINATED BY NORTHEAST TROUGHING AND
WESTERN UPPER HIGH/RIDGING INTO NEXT WEEK. SURFACE ANTICYCLONE OF
CANADIAN ORIGIN PERSISTS OVER THE WEEKEND WITH LOW HUMIDITY AND
OFFERS SEVERAL DAYS OF DRYING SUNSHINE.
THE NEXT CHANCE FOR RAIN COMES BY TUESDAY AS A SHORTWAVE TROUGH
DIVING SOUTHEAST FROM CANADA MOVES ACROSS THE GREAT LAKES. MODEL
SOUNDINGS BY WEDNESDAY AFTERNOON SHOW SOME POTENTIAL FOR STRONG
STORMS WITH DEEP LAYER SHEAR OF 30 KNOTS AND SFC-BASED INSTABILITY
WITH OVER 1000 J/KG OF CAPE...SO WE WILL CONTINUE TO WATCH HOW THIS
EVOLVES.
Detailed Forecast for Grand Rapids
Today
Mostly sunny, with a high near 81. Calm wind becoming west around 6 mph in the afternoon.
Tonight
Partly cloudy, with a low around 60. West wind around 6 mph becoming calm in the evening.
Sunday
Partly sunny, with a high near 83. Calm wind.
Sunday Night
Mostly cloudy, with a low around 63. Light and variable wind.
Monday
Partly sunny, with a high near 84. Light and variable wind.
Monday Night
Partly cloudy, with a low around 62.
Tuesday
Mostly sunny, with a high near 84.
Tuesday Night
A chance of showers after 2am. Mostly cloudy, with a low around 64.
Wednesday
A chance of showers, with thunderstorms also possible after 2pm. Partly sunny, with a high near 83.
Wednesday Night
A chance of showers and thunderstorms. Partly cloudy, with a low around 63.
Thursday
Mostly sunny, with a high near 81.
Thursday Night
Mostly clear, with a low around 61.
Friday
Sunny, with a high near 83.
The is the archive image from my Radarscope software from May 31, 1998
Yesterday we reached 80 and the morning low was 57.
Here is the updated long range guess for August
https://www.cpc.ncep.noaa.gov/products/predictions/30day/
Slim