NWS: Polar Vortex 2019: Coldest since 1996 with -56F in Cotton, MN, -28F Minneapolis

Written by on February 4, 2019 in United States of America with 0 Comments

Article from NWS Duluth

In late January 2019, a historic arctic outbreak brought bitterly cold wind chills and record-breaking cold temperatures to the Midwest. Many schools and some businesses and government offices were closed for three days, with USPS mail delivery even suspended on Wednesday, January 30th due to extremely dangerous wind chills. The coldest temperatures occurred on the morning on January 31st when Cotton, MN recorded a low of -56, approaching the Minnesota state record low of -60 set back in 1996.

The low of -56 at Cotton, MN was the coldest temperature recorded in the Lower 48 for this entire period of cold weather!

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Preliminary Coldest Temperature Reports for January 25-31, 2019
Northeast Minnesota
Location Low Temperature (°F) Date(s)
 COTTON -56 01-27, 01-31
 KABETOGAMA -50  01-31
 CELINA 2E -47  01-31
 INTERNATIONAL FALLS INTL AP -46  01-27
 BABBITT -46 01-27
 NORTHOME 3S -45  01-31
 BRIMSON 2S -45  01-27
 EMBARRASS -45  01-27
 CASS LAKE -44  01-31
 FLOODWOOD 3 NE -44  01-31
 TOWER 2S -44  01-27
 BRAINERD CROW WING COUNTY AP -43  01-31
 BIG FALLS -43  01-30
 ORR 3E -43  01-28
 BRAINERD -42  01-31
 ISABELLA 14W -42 01-27, 01-31
 GUNFLINT LAKE 10 NW -42  01-28
 SANDY LAKE DAM LIBBY -41  01-31
 POKEGAMA DAM -41  01-31
 LEECH LAKE -41  01-31
 ORR (RAWS) -41  01-27
 ELY (RAWS) -41  01-27
 WRIGHT 3 E -41  01-31
 HIBBING CHISHOLM HIBBING AP -40 01-27, 01-31
 EFFIE  (RAWS) -40  01-27
 LITTLEFORK (RAWS) -40  01-27
 ELY 25E -40 01-26, 01-30
 COOK 8NE -40  01-31
 ISLE 12N -39  01-31
 MOOSE LAKE 1 SSE -37  01-31
 CLOQUET -37  01-31
 BRUNO 7ENE -37  01-31
 GULL LAKE DAM -36  01-31
 HILL CITY (RAWS) -36  01-30
 TWO HARBORS 7NW -36  01-26
 BRAINERD (RAWS) -35  01-30
 EVELETH WASTE WATER PLANT -35  01-31
 ELY -35  01-31
 DULUTH NWS -35  01-31
 WALKER -33  01-25
 SAGINAW (RAWS) -33  01-30
 ISABELLA (RAWS) -33  01-27
 MOOSE LAKE (RAWS) -33  01-30
 DULUTH INTL AP -31  01-31
 PINE RIVER DAM -30  01-31
 TWO HARBORS -30  01-31
 WOLF RIDGE ELC -30  01-31
 GRAND MARAIS -27  01-27

 

Northwest Wisconsin
Location Low Temperature (°F) Date(s)
 BUTTERNUT 3SW -49  01-31
 COUDERAY 7 W -39  01-31
 GORDON -38  01-31
 CLAM LAKE 4W -38  01-31
 BRULE RANGER STATION -35  01-31
 WINTER -34  01-31
 SPOONER AG RESEARCH STATION -34  01-31
 HAYWARD RANGER STA -33  01-31
 GLIDDEN (RAWS) -33  01-26
 BARNES (RAWS) -29  01-27,

01-31

 ASHLAND KENNEDY MEMORIAL AP -28  01-31
 HURLEY -28  01-31
 ASHLAND 3S -27  01-31
 BAYFIELD FISH HATCHERY -27  01-31
 HAYWARD MUNICIPAL AP -25  01-26
 MADELINE ISLAND -25  01-31

Cold Record History

In the days before this arctic outbreak, meteorologists at the National Weather Service predicted that conditions could be favorable for record-setting cold, possibly approaching the Minnesota state record low of -60 set in Tower, MN in 1996. The Minnesota State Climatology office only considers observations from well-maintained weather stations official for the purpose of state records, which in the case of temperatures meant that only National Weather Service-installed and  maintained equipment – automated “ASOS” weather stations found at some airports and volunteer National Weather Service cooperative (“co-op”) observers.  Temperature observations from other platforms (many of which did not even exist in 1996), will not be considered because of potential data-quality control concerns, and the need to maintain continuity with the historical climatological database.  Some of the observing platforms that will not be considered include AWOS, RWIS, RAWS, and commercially purchased “backyard” weather stations.

Because volunteer cooperative observer sites mostly consistent of private citizens who volunteer to report, these observation locations have changed slightly over time. In particular, the locations at two of our historically cold locations, Embarrass and Tower, MN, have changed since the late-January/early February extreme cold event in 1996.  The co-op observers at that time have both since retired after many years of dedicated service.  Therefore, the NWS recruited new co-op observers at both of these sites, but the current location of the observation sites in both Tower and Embarrass are slightly different than in 1996. The current observer at Cotton, MN is also different from the previous observation location. When moving co-op observing sites due to a volunteer observer retiring, every attempt is made to ensure the integrity of the site’s historical record, but inevitably, some sites do require relocation.  It should be noted that this is not dissimilar to some of the main observing sites as well.  For instance, the official Duluth, MN observing site has moved 3 times since the inception of observations in 1874.

Cotton, MN

In addition to slight changes in location and elevation, the equipment used to measure temperature at these locations has changed, but the National Weather Service has very high confidence in the accuracy and integrity of the equipment currently in use. In 1996, the observations were taken with mercury-in-glass thermometers in a shelter box.  In 2019, the temperature observations have transitioned to modern high-accuracy digital thermometers which are now the standard across the National Weather Service national volunteer cooperative observing network. While we have very high confidence in the accuracy and integrity of these thermometers, they are, nonetheless, a different instrument than the mercury-in-glass thermometer standard used in 1996.

 

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