Monday, May 24, 2010

Cool Canadian Relief is 24 Hours Away

* Record heat Monday, 94 at St. Cloud, 95 in the Twin Cities, 93 at Eau Claire, WI. A complete list of Monday's highs from the local NWS office can be found here.

* 97 F. reported at St. James and Cambridge Monday afternoon, hottest in the state.

* Atmosphere remains "capped" over Minnesota Monday, too dry/hot aloft for T-storms to pop - later Tuesday the cap will break, and the risk of thunder will increase (but SPC is not expecting a widespread severe storm outbreak).

* Hot, dry, desert-winds gust over 40 mph.

* Nearly 4" of rain in Duluth Sunday, setting a new 24 hour rainfall record.

* 1.5" diameter hail reported from storms over far northern MN Monday, damaging rooftops, skylights, stripping leaves off trees.

* 90 possible again today, dew points close to 70 will make it feel like mid 90s.

* Strong T-storms possible late Tuesday as a cooler front approaches (probably not a widespread severe weather outbreak).

* Wind shift to the north/northwest pumps cooler, drier Canadian air into Minnesota - by late Thursday the air overhead will have HALF as much water as it does right now.

Monday Almanac. Every major weather reporting station in Minnesota saw highs in the 90s Monday, more than 20 degrees above average.

Flood Threat. The National Weather Service has issued a flood warning for far northwestern MN valid until 7 am Tuesday morning, but they may have to extend the warning, the result of storms reforming over the same counties near Thief River Falls. The latest USA warning map can be found here (keep clicking on Minnesota to zoom into specific states/counties).

Doppler Estimates. NWS Doppler out of Grand Forks as of 10:45 pm Monday night showed some 4-6"+ estimated rainfall amounts near Thief River Falls, all within a 24 hour period. The ground is saturated, waterlogged, incapable of soaking up any additional rainwater - it's all running off into streams and streets.

Enjoying May? Summer came swirling into Minnesota, right on schedule on Monday, boosting temperatures to record-levels, 20-30 degrees above average across the state. Yesterday felt like something right out of the Dog Days of early August, an exclamation coming at the end of our fast-forward spring.

Today won't be quite as hot, but if the sun stays out for a few hours during the morning and midday hours (likely) we stand a very good chance of hitting 90 once again. Throw in a dew point in the mid to upper 60s and the THI, the temperature-humidity index will reach the mid 90s, reaching into the danger zone. Take it easy out there today; the good news: a cooler front arrives Wednesday as winds shift around to the north, the worst of this oppressively muggy airmass will get shoved towards Milwaukee and Chicago, and we'll finally be breathing easier again. I expect a 20-30 degree drop in dew point by Friday, meaning that by the end of the week there will be approximately HALF as much water in the air (for every 20 degree drop in dew point the amount of water vapor drops by roughly 50%)

Relief. The "wall of water" just west of Minnesota, a towering line of strong/severe thunderstorms, marks the leading edge of cooler, drier, more comfortable air destined for Minnesota. Models print out an average of 1/3rd of an inch of rain later today and tonight, by Wednesday winds swing around to the north/northwest and a welcome cool-down will begin. To see the very latest weather map click here.

Good news indeed.

Now, about that major holiday weekend on the way:

Saturday: (A-/B+) Expect a comfortably cool Saturday with sun giving way to increasing clouds, winds from the south/southeast at 10-20, highs holding in the 60s north, low 70s southern lakes (wake-up temperatures in the 40s, so take a jacket or sweatshirt). Showers/storms enter far western MN by Saturday night.

Sunday: (C-). It won't rain the entire day, but an eastbound cool front will mean more clouds, a few hours of showers, possible thunder (although it may be too cool for any T-storms). Expect highs mostly in the 60s, gusty south/southwest winds gusting to 20 mph. Sunday looks like the worst day of the holiday weekend, but again, not a total wash-out.

Memorial Day: (A-). Possibly the nicest day of the holiday weekend, plenty of sun, warmer than Saturday (or Sunday) with highs near 70 north, mid 70s southern lakes, a northwest breeze at 10-15 mph with low humidity, a little more like early September than late May. Again, 2 out of 3 days look pretty good, cooler than recent days, but enough sun for outdoor activities. We've seen worse - much worse!

Stories Worth Reading...

* Are They Paying Attention?

* Living in Denial.

Paul's Conservation MN Outlook for the Twin Cities and all of Minnesota

Today: Partly sunny, hot and humid. T-storms possible by late afternoon or evening. Winds: S 10-20+ High: near 90 (heat index: mid 90s)

Tonight: A few T-storms expected. Low: 67

Wednesday: Partly sunny, turning breezy and cooler - a welcome dip in humidity. High: 83

Thursday: Bright sun, low humidity - very pleasant! High: 81

Friday: Plenty of sun, still beautiful. High: 77

Saturday: Cool, with sun giving way to increasing clouds - showers possible far west by Saturday night. High: 73

Sunday: More clouds, unsettled, a few hours of showers expected, possible thunder. High: 69

Memorial Day: Sun on the increase, less humidity - probably dry. High: 75

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