Instant Summer!

With a May like this who needs July? Yesterday’s extreme heat was a). amazing, and b). supremely humbling. 97 in the Twin Cities, smashing, obliterating the old record of 89 set most recently in 1978. Keep in mind the normal high is 71 degrees. Granite Falls hit an astounding 100 degrees in the shade, readings in the upper 90s from the southern suburbs of the Twin Cities and much of southern Minnesota. Check out the long list of records from the NWS below.

What happened? Good question. Computer models were predicting mid 70s for the metro area yesterday, but I saw that one of the models was predicting a 2 meter temperature of 82 by mid afternoon, so I upped the high to near 80. By midday (with a temperature of 86) I upped the high into the low 90s, knowing the record high was 89. A meteorologist NEVER predicts a record high! That would be borderline delusional. The odds are never in your favor when one goes out on a limb like that. Flying back from Annapolis I heard the pilot announce a current temperature of 94, only to get home and discover that the high was really (drumroll please) a whopping, record-smashing 97. A tongue of inflamed, desert air swept northeastward, and strong subsidence, sinking, drying air — warmed even more dramatically than the computers were suggesting, gusty winds at the surface adding to this “compressional warming”. It’s much the same effect when you pump air into your bicycle tires, it warms up rapidly. So it goes with the atmosphere: when air sinks rapidly it can warm dramatically, with some wild results. I’ve heard rare cases where strong downdrafts in the vicinity of severe thunderstorms have resulted in rapid spikes in temperature, sometimes a 30-40 degree rise in a few minutes! Frankly, I’m at a loss for answers here — my hunch is that it was a combination of compressional warming, gusty south winds at the surface, and the origin of this extraordinarily dry airmass (desert southwest).

Wednesday may be nearly as hot. The same (desert) airmass will be draped over Minnesota, a south to southwest wind gusting to 30 mph at times, and highs should rise well into the 80s to near 90. More mid 90s are possible over the southern third of Minnesota. T-storms may slosh into the Red River Valley by late in the day, but no cooling rain is expected until late Wednesday night and Thursday morning, when .10 to .30″ of rain may fall (and temperatures will cool down significantly).

A weak bubble of high pressure will keep most of the showers and T-storms to our south Friday, Saturday and much of Sunday (although a little rain my creep into far southern counties of Minnesota). By Monday, Memorial Day, moisture from the Gulf of Mexico will finally spurt north, fueling a few showers and T-storms, but I still don’t think it’s going to rain the entire day. More clouds and a few hours of rain will certainly mean slightly cooler temperatures (and higher humidity). Throw in a falling barometer and you might actually have pretty good conditions for catching fish, especially on Memorial Day (I’m trying like heck to find a silver lining here!)

So, dress light today — it will border on STINKING HOT by the time you get out of work or school later today. The good news: it will only last 1 more day. Between a little Thursday rain and a slight cooler front of Canadian origin arriving Friday I do see some relief in time for the holiday weekend. Is this a sign that the summer will be blazing hot with a run of 90s? Not necessarily — this is more of a meteorological fluke, an aberration. Maybe that’s wishful thinking on my part. The summer weather is a riddle, wrapped in an enigma. Take any long-long range outlook with a huge grain of salt. The short-range forecast is tough enough!

Weather Headlines

• Record heat grips the southern third of Minnesota Tuesday, 97 in the Twin Cities, 94 in Rochester, 100 degrees reported at Granite Falls, nearly 30 degrees warmer than average.

• Grand Marais: Tuesday afternoon temperatures hold in the mid 30s, nearly a 70 degree temperature contrast across the state!

• Wednesday: nearly as hot, low to mid 90s south, near 90 central, 70s up north.

• T-storms reach the Red River Valley late Wednesday, spreading across the rest of Minnesota Thursday morning.

• Weak bubble of high pressure keeps most of the rain/storms over Iowa and Nebraska Friday, Saturday and Sunday…. risk of showers, T-storms increases on Memorial Day (few hours of rain possible).

• Weekend temperatures much closer to average for late May, 60s north, 70s south.

For a detailed list of most Minnesota towns, yesterday’s highs, and comprehensive weather information for the past 5 days (including highs/lows/precipitation) click here.

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