Moderate Risk of severe thunderstorms over much of Minnesota by this evening/tonight.
87 F. high in the Twin Cities Sunday.
84 F. average high on July 20.
82 F. high on July 20, 2013.
July 20 in Minnesota Weather History. Source: MPX NWS:
2002: Dew points reached 84 degrees at Madison, Morris, and Olivia. This ties the all- time highest dew points seen by the State Climatology Office for Minnesota.
1934: Temperature topped out at 113 at Milan.
Heat Spike - MCS Risk
"Wow, I sure am enjoying this 100-degree heat index!" said no one, ever. Today will be a test: jungle-like heat and humidity, followed by an outbreak of potentially violent storms by tonight. Yes, something for everyone. And a far cry from last Monday, when a swirl of Canadian air had us reaching for sweatshirts and fiddling with our furnaces.
The good news, this instant-on heat wave lasts 1 day. Highs in the mid-90s, coupled with a drippy dew point rising into the upper 70s, will make it feel like 100-105F by late afternoon. The urban heat island adds a few more degrees, and there's now an Excessive Heat Warning for the 7-country metro area.
The atmosphere becomes explosively unstable by late afternoon; a ripple of low pressure approaching from the Dakotas sparks a possible MCS by evening: a meso-convective system, which is a particularly intense, fast-moving squall line capable of 70-85 mph wind gusts.
NOAA SPC has elevated the risk to "moderate" across much of Minnesota. It may be tough getting much sleep tonight with all the crashing & banging. I could see power outages, so have flashlights & candles ready to go.
Relief arrives midweek as dew points drop into the 50s.
But today? Stay hydrated and keep an eye on the northwest sky.
* graphic above: Twin Cities National Weather Service.
WRF: 10 PM Tonight. NOAA's high-resolution, 4 km WRF model shows a possible MCS or derecho pushing out of the Red River Valley into northern and central Minnesota early tonight, the bow-echo appearance suggestive of strong, even violent straight-line winds impacting the Brainerd and Alexandria lakes area, as well as Little Falls, Duluth. and possibly St. Cloud and the Twin Cities. The risk of wind damage appears greatest north of MSP. Map: HAMweather.
Flash Flood Risk. NOAA WPC shows a slight chance of training T-storms with rainfall rates high enough to spark potential flash flooding from near Fargo, Little Falls and Brainerd to Duluth and the North Shore.
...DANGEROUSLY HOT AND HUMID CONDITIONS EXPECTED LATE MONDAY MORNING THROUGH MONDAY EVENING... AN EXCESSIVE HEAT WARNING IS IN EFFECT FOR THE TWIN CITIES METROPOLITAN AREA...WITH A HEAT ADVISORY IN EFFECT ACROSS THE REST OF CENTRAL AND SOUTHERN MINNESOTA AND FAR WESTERN WISCONSIN...FROM LATE MONDAY MORNING THROUGH MONDAY EVENING. HIGH TEMPERATURES ARE EXPECTED TO REACH THE LOWER 90S. THIS COMBINED WITH OPPRESSIVE DEW POINTS IN THE MIDDLE TO UPPER 70S WILL RESULT IN HEAT INDICES RANGING FROM 100 TO 110 DEGREES. THE WARMEST CONDITIONS WILL BE FOUND IN THE MINNESOTA RIVER VALLEY. ...EXCESSIVE HEAT WARNING REMAINS IN EFFECT FROM 11 AM TO 9 PM CDT MONDAY... * TEMPERATURES...HIGHS IN THE LOWER 90S WITH HEAT INDICES AROUND 105 DEGREES. * IMPACTS...GIVEN THE COOL SUMMER THUS FAR...THESE CONDITIONS MAY LEAD TO A HEIGHTENED RISK OF HEAT RELATED STRESS AND ILLNESS... ESPECIALLY FOR THE YOUNG AND ELDERLY...AND THOSE WITHOUT AIR CONDITIONING.
Photo credit above: "Waterman Complex wildfire at Ochoco Pass." Credit: InciWeb.
File photo above: DNR.
• Abnormally strong bursts of Saharan dust are drifting over the Atlantic — and may subdue the tropics like they did last year, experts say.
• The tropical Atlantic is cooler than normal for the moment, making it harder for storms to bulk up..."
TODAY: Excessive Heat warning, severe storms possible by evening. Winds: S 10-15. Dew point: 77. High: 93 (heat index: 100-105).
MONDAY NIGHT: Tropical humidity levels with T-storms, some severe (especially north of MSP). Low: 75
TUESDAY: Unsettled, isolated T-storm possible. Dew point: 71. High: 86
WEDNESDAY: Sunny, breathing easier. Dew point: 57. Wake-up: 64. High: 81
THURSDAY: Less sun, few storms south/west. Wake-up: 61. High: near 80
FRIDAY: Sticky, few more T-storms. Dew point: 66. Wake-up: 63. High: 80
SATURDAY: The nicer day of the weekend; T-storms up north. Wake-up: 67. High: 83
SUNDAY: Early sun, PM showers, T-showers. Wake-up: 63. High: 73