“Fire Weather” & 90 in metro & southern MN: What is a “Red Flag Warning?”

83F high at MSP Airport Monday (at 4:24pm)

74F average high for September 10th

+5.2F – temps vs. average at MSP so far in September

15th straight month of above average temps?

100F in Rapid City, SD Monday

102F in Phillip, SD Monday

90s in southern MN Tuesday

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Source: Twin Cities NWS

“Explosive Fire Growth” potential through Tuesday

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Source: NOAA/SPC

Red Flag Warnings flying for most of MN & 11 other states

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Source: NOAA

What exactly is a “Red Flag Warning” anyway?

Welcome to the new Minnesota climate.

NWS terms like “Blizzard Warning” and “Bitter Cold” seem passé. “Extreme Heat Watches” and “Red Flag Warnings” are in vogue.

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I worked in Arizona for 9 years where Red Flag Warnings are commonplace.

We’re just not used to hearing (and understanding) these terms in Minnesota.

So here’s a crack at understanding these new additions to our Minnesota weather lexicon.

-A RED FLAG WARNING MEANS THAT CRITICAL FIRE WEATHER CONDITIONS ARE EITHER OCCURRING NOW…OR WILL SHORTLY. A COMBINATION OF STRONG WINDS…LOW RELATIVE HUMIDITY…AND WARM TEMPERATURES WILL

CREATE EXPLOSIVE FIRE GROWTH POTENTIAL.

Basically you can think of Red Flag Warnings as a major advisory to be careful with fire. Bonfire tonight? Burning some excess brush? Maybe not the best idea. It’s so dry out there that any embers that get away start a fire quickly…then gusty winds can make the fire spread quicker than you can get a handle on.

Wildfires are a whole different animal. A severe thunderstorms can ruin your day…knocking down trees and branches. A fast moving wildfire can burn your home to the ground in a few minutes.

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Source: Twin Cities NWS

Here’s more from the Twin Cities NWS on our Red Flag Warning.

…RED FLAG WARNING IN EFFECT UNTIL 9 PM CDT TUESDAY FOR WIND AND

LOW RELATIVE HUMIDITY FOR MUCH OF CENTRAL AND EAST CENTRAL MINNESOTA…

THE NATIONAL WEATHER SERVICE IN TWIN CITIES/CHANHASSEN HAS ISSUED A RED FLAG WARNING FOR WIND AND LOW RELATIVE HUMIDITY…WHICH IS IN EFFECT UNTIL 9 PM CDT TUESDAY.

* WINDS…SOUTH 20 TO 25 MPH WITH GUSTS UP TO 35 MPH.

* TIMING…THIS AFTERNOON INTO THIS EVENING…AND THEN AGAIN

TUESDAY INTO TUESDAY EVENING.

* RELATIVE HUMIDITY…AS LOW AS 20 PERCENT.

* TEMPERATURES…HIGHS TODAY FROM 80 TO 85. HIGHS TUESDAY 88 TO

93.

* IMPACTS…FIRES COULD GROW QUICKLY AND BECOME FAST MOVING DUE

TO THE GUSTY WINDS AND LOW HUMIDITY.

A much cooler front will bring an opportuntiy for much needed showers, cooler temps and higher humidities (and greatly reduced fire danger) by Wednesday & Thursday.

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9-11 Heat wave: One more shot of 90+ heat

The timing Tuesday looks excellent for the hottest temps of September in southern Minnesota.

Temperatures Monday PM n the “upstream air mass” soared to 100 degrees in Rapid City, SD.

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Source: University of Illinois

That “thermal ridge” or the axis of the hottest air will be right over Minnesota Tuesday.

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Source: NOAA

I don’t think we’ll see temps quite that warm in Minnesota Tuesday, but mid-90s seem very likely. One last day of humming AC units? At least dew points will be in the 50s, so it will indeed be a “dry heat.”

Looking ahead, this may very well be the last 90 degree temp in 2012 in the metro…so enjoy it if that’s you’re thing.

Daylight wanes:

One September feature we all notice this time of year is the rapidly fading daylight. Tuesday’s sun angle and intensity is about equal to March 30th! The 7:30pm sunset this week is the earliest since March 23rd.

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Source: http://www.opentopia.com/sunlightmaprect.html

With 12 hours & 40 minutes of daylight on Wednesday, we’ve lost about 3 full hours of daylight since the summer solstice in late June.

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Source: http://astro.unl.edu/classaction/animations/coordsmotion/daylighthoursexplorer.html

Evening walks & boat rides are wrapping up earlier these days.

Even so, I still contend that some of the best 45 days of weather are ahead in Minnesota.

After our chilly spell and September reality check next week, it looks like milder days may return by late September.

We may still enjoy more 80 degree temps in the incredible “6 month summer” of 2012.

PH

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