Stare at the weather maps long enough and you begin to hallucinate. I've been telling you (ad nauseum) for years that something has changed on the maps - the pattern isn't even close to what I grew up with in the 70s and early 80s. Weather getting "stuck" for extended periods of time. Odd gyrations in the jet stream steering winds.
John Mason at Skeptical Science writes: "Evidence is mounting to indicate that the response of the jet stream to polar amplification has been to tend to slow down and meander more, with a greater tendency to develop blocking patterns, which in turn prolong and intensify all sorts of extreme weather events."
Northern latitudes are warming faster than mid latitudes, resulting in a 12 percent drop in average jet stream winds, which may slowing storms and hot high pressure ridges.
All or nothing? Drought or flood?
Speaking of sweeping north-south sweeps in the jet stream - an early taste of September will keep us in the 60s today; a ragged, windblown sky and a PM instability shower. Although cool for the lake temperatures slowly mellow over the weekend; Sunday the nicer day with more sun & less wind.
A 90s rerun? Not until the second week of August.
Image credit above: "The only three storms that were at least tropical storms at or near Dorian’s longitude during July going back to 1851." (NOAA).
Tropical Storm Dorian Update from Alerts Broadcaster (issued Thursday afternoon):
* 60 mph sustained winds; Dorian has showed slow but steady strengthening over the last 24 hours.
* Dorian forecast by most models to track north of Lesser Antilles, U.S. Virgin Islands and Puerto Rico in a Sunday-Monday timeframe, possibly reaching the Bahamas by Tuesday of next week.
* Model skill levels and confidence are (very) low for any track/intensity beyond next Tuesday. Dorian may still impact the USA, but it's too still too early to provide specifics.
Summary: Although the final track of Dorian is very much up in the air, we need to treat this storm (like all Atlantic storms) with a fair amount of respect. History shows that the storms during the first half of the season are the ones that wreak the most havoc. Out of 74 hurricane names "retired" by NOAA NHC - 59 were the A-K storms, only 15 the K-Z storms. A high-amplitude pattern (big north/south gyrations in the jet stream) might be able to pull any tropical system in the Gulf of Mexico or Bahamas unusually far north next week, depending on timing, so we all need to pay attention in the days ahead. We're looking for model trends, continuity and consistency - the signal amidst the noise of the long-range weather simulations. We'll keep you posted on the trends and potential for Dorian to reach the U.S. coastline.
Photo credit above: "Outlawing a type of insecticides is not a panacea." AP Photo/Ben Margot
Animation credit: 30 Day Arctic ice animation. United States Naval Research Laboratory, Stennis Space Center, Mississippi.
Photo credit above: "Leading Arctic expert Prof Wadhams warns that a summer ice free Arctic in 2 years could trigger dangerous methane release." Photograph: Jenny E Ross/Corbis.
Photo credit above: M.I.T.