Wind Advisory – Storm WarningsOctober 28th, 2012 at 7:25 pm by Bill Steffen under Bill's Blog, Weather
This thread deals with the effects of “Sandy” on West Michigan and Lake Michigan. A Wind Advisory will be in effect from 5 PM Monday to 8 PM Tuesday. Wind gusts will reach 35-50 mph with the strongest winds along the Lake Michigan shore, especially from Allegan Co. to the south, where a north wind comes off the water. Cold air coming over relatively warm water will make stronger winds and bigger waves than warm air coming over cold water. That’s physics. There will be Gale Warnings (34 to 47 knots or 39-54 mph) for Lake Michigan from 2 PM Monday to 5 AM Tuesday EDT. At 5 AM, the Gale Warning is upgraded to a Storm Warning, which will be in effect from 5 AM to 5 PM. At 5 PM Tuesday, the Storm Warning will go back to a Gale Warning. Storm Warnings are rare. A STORM WARNING MEANS WINDS OF 48 TO 63 KNOTS ARE IMMINENT. A “knot” is a nautical mile per hour. One knot is 1.15077945 mph. So when they say 48 to 63 knots, that’s 55.2 to 72.5 mph. The National Weather Service says: “* WINDS…NORTH GALES TO 35 KT STARTING MONDAY AFTERNOON INCREASING TO 50 KT STORM FORCE WINDS LATE MONDAY NIGHT THROUGH LATE TUESDAY AFTERNOON. GALES WILL THEN CONTINUE THROUGH WEDNESDAY EVENING. * SIGNIFICANT WAVES…12 TO 16 FT MONDAY AFTERNOON BUILDING TO 20 TO 25 FT TUESDAY MORNING…THEN SUBSIDING TO 12 TO 16 FT LATE WEDNESDAY NIGHT. * OCCASIONAL WAVES…TO 20 FT MONDAY AFTERNOON…BUILDING TO 33 FT TUESDAY MORNING…THEN SUBSIDING TO 28 FT WEDNESDAY NIGHT. You would not get a 33-foot wave at shore. A wave is as deep as it is high above the water, and as the wave comes into shallower water, the wave “breaks” (the top falls over as the bottom drags). The strong north wind will will cause what’s called a “standing seiche” on Lake Michigan (similar to what occurred in Oct. 2010) from a similar deep low pressure center), with water piling up at the south end of the lake. Expect the water level (which fortunately is low right now) to rise up to 2-3 feet at the south end of Lake Michigan (and to fall 2-3 feet at the north end of Lake Michigan). Then add the huge waves on top of that and there is the potential for significant beach erosion and damage to whatever is at the shore. We’ll also have cloudy skies, a good chance of a period of rain and chilly temperatures. The cold air (temperatures in the upper 30s to mid 40s) combined with the strong wind, will result in wind chill readings in the upper 20s to low 30s.
Latest model data: 00Z Monday NAM (Caribou) wind forecast is very similar to past runs of the model…15-20 mph winds this Monday midday-afternoon, peaking at a steady 25 mph Tues. mid-morning. The model gives us a fairly steady light rain starting later Tuesday AM thru Weds. evening with 1/2″ total for G.R. The model does print out a brief mix of sleet/ice pellets at the start of the precipitation. I mentioned that the winds would be stronger near Lake Michigan. The model gives S. Haven a steady wind of 33 knots late Monday night and Tuesday morning, that’s 37 mph! That’s about 10 mph faster than Grand Rapids. The GFS model give G.R. a steady 25-29 mph wind for Tues.
Links: WOOD-TV Interactive Radar, looping radar. Check out the current conditions in Michigan, current conditions in Indiana, current conditions in Illinois, regional radar, GRR radar, northern Indiana radar, Chicago radar and Milwaukee radar. Here’s the College of DuPage Radar Map, Storm total rainfall, the local warning/advisory map and the National warning/watch/advisory map. You can checkout the latest Grand Rapids NWS discussion, the Northern Indiana NWS discussion (includes the Michigan Counties that border Indiana), the discussion for Northern Lower Michigan, and Eastern Lower Michigan. Here’s the Spyglass Condos Weather Station the S. Haven GLERL station, the Muskegon GLERL station, the Grand Haven Steelheaders webcam and weather station, and the weather station at Holland State Park. Check out the WOOD lightning tracker and U.S. lightning and links to webcams. Here’s the infrared satellite loop (night) and the visible satellite loop (daytime). Here’s Lake Michigan water temperatures. Here’s storm total rainfall for W. Michigan and E. Michigan. Here’s data from the mid-lake buoy, the GLERL Weather Station at Michigan City, Indiana…and the Harrison Crib (Chicago Water Intake), 3 miles east of downtown Chicago out in the lake. Both of these last two stations will really show some wild winds. The Michigan City, IN beach station was already showing 35-40 mph wind gusts Sunday evening.