More on Cold

A couple of items of quick follow-up are warranted regarding the holiday-season cold snap of 2019.  First, here's a summary of low temperatures from the NWS:

PUBLIC INFORMATION STATEMENT...CORRECTED
NATIONAL WEATHER SERVICE FAIRBANKS AK
438 PM AKST SAT DEC 28 2019

...NORTHERN ALASKA COLD SPELL LOW TEMPERATURE REPORTS...

BELOW IS A SUMMARY OF MINIMUM LOW TEMPERATURE OBSERVATIONS DURING
THE RECENT COLD SNAP ACROSS NORTHERN ALASKA. THE -60 F AT BETTLES,
IF ACCEPTED BY THE NOAA NATIONAL CENTERS FOR ENVIRONMENTAL INFORMATION,
WOULD TIE THE ALL-TIME DECEMBER RECORD LOW SET IN DECEMBER 15, 1946. 

OBSERVATIONS ARE COLLECTED FROM A VARIETY OF SOURCES WITH VARYING
EQUIPMENT AND EXPOSURES. DATA IS CONSIDERED PRELIMINARY UNLESS
NOTED AS OFFICIAL. WE THANK ALL VOLUNTEER WEATHER OBSERVERS 
FOR THEIR DEDICATION.


LOCATION                     TEMP       LAT/LON            TIME/DATE 

MANLEY HOT SPRINGS 15 MI NE  -65 F      65.14N/150.22W     0800 AM 12/28 (OFFICIAL)      
ALLAKAKET (FAA-ALASKA)       -60 F      66.55N/152.63W     1220 PM 12/28
BETTLES                      -60 F      66.92N/151.52W     0153 AM 12/28       
CHALKYITSIK RAWS             -57 F      66.60N/144.35W     0120 AM 12/28  
NOWITNA RIVER                -57 F      64.50N/154.13W     1205 AM 12/28  
ARCTIC VILLAGE               -57 F      68.12N/145.57W     0956 AM 12/27  
FORT YUKON                   -56 F      66.57N/145.27W     0803 PM 12/27    
TELIDA RAWS                  -56 F      63.43N/153.35W     0953 AM 12/27      
NORUTAK LAKE RAWS            -55 F      66.83N/154.32W     0721 AM 12/28  
TANANA                       -55 F      65.17N/152.10W     1152 AM 12/27 (OFFICIAL) 
MANLEY HOT SPRINGS DOT CAMP  -54 F      65.01N/150.61W     1000 PM 12/27       
COLDFOOT (FAA-ALASKA)        -52 F      67.26N/150.19W     1040 AM 12/27  
HUSLIA                       -52 F      65.70N/156.35W     0656 AM 12/27  
WISEMAN NWS COOP             -52 F      67.42N/150.11W     0700 AM 12/27 (OFFICIAL)      
NIKOLAI                      -51 F      63.02N/154.35W     0655 AM 12/27  
KALTAG                       -49 F      64.33N/158.75W     0553 AM 12/28 (OFFICIAL)
MCKINLEY RIVER RAWS          -50 F      63.65N/151.64W     1050 AM 12/27  
GALENA                       -49 F      64.73N/156.93W     0756 AM 12/27
SEVEN MILE RAWS              -49 F      65.94N/149.85W     0219 AM 12/28     
CLEAR SKY LODGE NWS COOP     -46 F      64.25N/149.18W     0806 PM 12/27 (OFFICIAL)
UMIAT AIRFIELD RAWS          -46 F      69.37N/152.14W     1023 AM 12/28  
SHUNGNAK                     -45 F      66.88N/157.17W     1117 AM 12/28  
SALCHA RAWS                  -45 F      64.59N/146.15W     0852 PM 12/27  
UAF TOOLIK FIELD STATION     -45 F      68.63N/149.60W     1100 AM 12/28  
AMBLER                       -44 F      67.10N/157.85W     0456 AM 12/28
EIELSON AFB                  -44 F      64.67N/147.10W     0857 PM 12/27 (OFFICIAL)  
FORT WAINWRIGHT              -44 F      64.83N/147.62W     1013 PM 12/27 (OFFICIAL)
NENANA                       -44 F      64.55N/149.08W     0922 PM 12/27 (OFFICIAL)      
NUIQSUT                      -44 F      70.22N/151.00W     0353 PM 12/28 (OFFICIAL)             
MCGRATH                      -43 F      62.97N/155.62W     1213 PM 12/26 (OFFICIAL)      
BUCKLAND                     -42 F      65.98N/161.15W     0811 PM 12/27  
MINCHUMINA                   -42 F      63.90N/152.32W     0256 AM 12/27  
DEADHORSE                    -41 F      70.20N/148.47W     0253 AM 12/28 (OFFICIAL)     
GOLDSTREAM CREEK NWS COOP    -41 F      64.89N/147.88W     0954 PM 12/27 (OFFICIAL)          
FAIRBANKS AIRPORT            -40 F      64.80N/147.85W     0553 PM 12/27 (OFFICIAL)  

The "preliminary" label attached to the observations has some significance in this case, because there's serious doubt concerning the -60°F at Bettles.  The problem is that the ASOS thermometer reported a minimum of -57°F, but the climate observation was manually adjusted down to -60°F.  Here's the proof... the original midnight (actually 23:53 AKST) METAR was available by 23:55 as follows (I've highlighted the 24-hour minimum, -49.4°C or -57°F):

METAR PABT 280853Z 00000KT 10SM CLR M48/ A2983 RMK AO2 SLP148 T1483 414831494 58022

Then two minutes later another 23:53 METAR became available with a manual correction:

METAR PABT 280853Z COR 00000KT 10SM CLR M48/ A2983 RMK AO2 SLP148 T1483 414831511 58022

The ASOS instruments did not measure a temperature below -57°F; this was a manual correction by the FAA observer based on some other information.  NOAA/NCEI may decide to throw out the correction; it's obviously a small difference, but it has some significance in view of the potential for a new December cold record at the site.

On another note, with changing pressure patterns across the state, extreme cold in certain areas has given way to extreme wind chills in others.  For instance, Deadhorse this morning reported a temperature of -38°F with a 21 mph sustained wind, equating to a wind chill of -72°F.  Perhaps surprisingly, more than half of winters in Deadhorse do not see a wind chill this low; and only once in recent decades has the wind chill dropped below -80°F (January 23, 2012).  The record low wind chill prior to the New Year in Deadhorse is -75°F.

Conditions have been nasty in western and southwestern Alaska, too.  Bethel reported -18°F with 28 mph winds yesterday afternoon, for a wind chill of -49°F.  Again, this is very unusual for this early in the winter; in the ASOS era (1998-present), the record low wind chill for December is -56°F.

Here's the 3am surface/MSLP analysis from Environment Canada (click to enlarge).

Finally, it was interesting to see temperatures jump up in the coldest parts of the interior last night as winds broke through the inversion and mixed down warmer air.  Here's an example from the Chalkyitsik RAWS near Fort Yukon.