Fairbanks above Zero

The temperature at the Fairbanks Airport at 11am AST Tuesday was +5F. This is the first time temperature has been above zero at the airport since 9pm AST December 23. Through 3pm AST it's been up to +15F.

If you're keeping score at home, that's 17 days and 14 hours continuously below zero. That's the longest such streak since Jan 13-Feb 4, 2006.

Here's the 330pm NOAA-15 GOES image showing the storm responsible for the break in the cold weather.

Warming Up

Warming up aloft at least, with a pretty good inversion developing up Monday evening. The 8pm AST GOES-15 infrared image shows the leading edge of the cirrus associated with the complex low in the North Pacific approaching Fairbanks, though the deep cloud layer is only to the Kenai peninsula.

At 8pm AST Monday,

Fairbanks Aiport -35F
Goldstream Creek: -35F

Clearly Summit: -6F
Keystone Ridge -10F

Another 40 below Day at Fairbanks

Blazing noon-time sunshine in downtown Fairbanks (webcam image courtesy of the News-Miner). The temperature at the airport snuck down to 41 below around 2am this morning. This makes this the 6th day with a low of 40 below or lower this month, and the 7th thus far this winter.

Just Like Winter

Here's a plot of temperatures and wind speeds today from the Eagle Summit Snotel, at 3700' MSL on the Steese Highway. At 11pm, 31 below with 30 mph hourly average wind speed. That's just like winter. Only colder.

Update:

The wind chill at Eagle Summit bottomed out at -69F at midnight: -32F with sustained 29 mph winds.

Temperature Update

Forget all this complex analysis stuff, here's a simple plot daily temperatures here Fairbanks thus far this winter.

The gray line is the 1981-2010 normal and the gray band around that is one standard deviation, so temperatures within that band would be "typical" for the season.

Tok Snowfall

There are two cooperative stations right in Tok.

One has reported about 27 inches of snow thus far this season, with 23 inches on the ground on January 6th. The other has reported 46 inches for season with 20 inches on the ground.

At Tok, an area that does not get too much wind, a 23 inch snow depth with 27 inches for the season by early January is not physically realistic.

A total of 46 inches is much more realistic for a 20 inch snow depth. Snowfall is indeed significantly above normal thus far this season in Tok.

Updated:

Here's a plot of the Feb 01 (more or less) snow depth at Tok since 1960 at the NRCS snow course.

Alaska Grab Bag

Some miscellaneous tidbits from around Alaska in this active winter weather:

It's another cold one Saturday morning in the western Interior. Lows through 10am include 54 below in Huslia and Tanana and 53 below at Galena and Kaltag. Here's an icy foggy webcam shot (courtesy of the FAA) from Ambler late Saturday morning, where it was 40 below at the airport, up on the ridge above town.

On Thursday, Nome dipped to 40 below for the first time since 1999, and Friday was the 10th straight day with a low of 30 below or lower. This is now the most severe cold snap in the Gold Rush City since January 1989, the big kahuna of western Alaska cold snaps.

Valdez received 38.5 inches of snow Thursday and Friday, with 272.1 inches of snow for the season and a snow depth of 76 inches. The record winter snowfall in Valdez is 560.7 inches in 1989-90.

The Beat Goes on, Still

Here's an updated plot of the standardized temperature departures thus far this winter. The correlation between the valley (Fairbanks Airport) and hills (Keystone Ridge) is 0.85, good but nowhere near perfect given that the two sites are only 14 miles apart.

After the 1-2 inches of snow Friday, skies cleared quickly around sunset and valley temperatures dipped to around 40 below late Friday evening, with overnight lows of 42 below at the airport and 41 below at Goldstream Creek. Here on the hill the temperature hit 27 below about 9pm.

Like a Yoyo

Wild temperature swings in Fairbanks-land. Still, Friday is the 10th day in a row here at Keystone Ridge with a low temperature of 20 below or longer, the longest such streak since the great 1999 cold snap (which was far colder than this).

That’s a Lot of Warming

Here’s a plot of the soundings from Fairbanks for 3pm Wednesday and 3am and 3pm Thursday. That is a lot of warming, though there is not any front involved in any usual mid-latitude sense.

Temperatures be a'changing

Temperatures since noon yesterday at Keystone Ridge (1600' MSL) and the Fairbanks Airport.

Deep Cold Air

This morning's upper air sounding is a fairly typical one for a deep cold airmass in Interior Alaska. There is a shallow layer near the surface with temperatures nearly constant, a transition layer where the temperature increases fairly smartly with height, and then the "warmest" air is above that. On this morning's sounding, between 3000 and 10000 feet above the ground, the temperature only varies by a few degrees, and the warmest temperature (+1F) was at nearly 7000' AGL.

This illustrates nicely that super strong inversions are NOT a feature of deep cold; the strongest inversions occur when skies are clear and it is warming aloft.

Low temperatures in the valley this morning were a couple hours either side of midnight, with the Airport bottoming out at 39 below. Clouds have since come in broken the small inversion that formed late last evening. At hill elevations that are still in the coldest layer, temperatures have been close to 30 below since yesterday. The very highest weather stations in Fairbanks-land, those above 2300' MSL, are the only sites reporting temperatures warmer than 10 below this morning. At the Caribou Peak RAWS, at 2500' MSL north of Poker Flats, temperatures in the past 24 hours have held between zero and 9 below.

Normalcy Departs

Steep inversions are the rule this time of year in Interior Alaska, but this is not one of those times. The afternoon sounding reveals a more than 20C inversion, but it's quite gradual by Interior standards. Temperatures at typical residential hillside elevations are back down to around -30F this evening; it's only above about 2000' MSL that temperatures are near -10F.

One interesting feature of this sounding is in the lowest 100 meters, where the temperature is constant (jargon=isothermal). This is typical in ice fog.

Normalcy Returns

All is right with the world, or at least as it concerns Interior Alaska inversions. With clear skies, temperatures in the valleys have been falling for more than 12 hours now, while temperatures have been slowly rising at elevation. The inversion is not yet especially steep, so elevations where appreciable numbers of people live are still chilly, but mostly warmer than it was Monday afternoon:

Low elevation min temperatures through 9am include:

Fairbanks Airport: -44F
Fort Wainwright: -44F
Eielson AFB: -42F
Goldstream Creek: -42F
UAF West Ridge: -38F

High elevation temperatures around 9am:
Munson Ridge: -7F
Clearly Summit: -8F
Keystone Ridge: -15F
Goldstream Toboggan: -27F

Still Cold

Here's an updated plot of the soundings from Monday: free air temperatures are a little bit warmer at low levels and a little cooler above 400 meters AGL.



Temperatures here one Keystone Ridge have been between 27 and 31 below all day: the low of -31F occurred most recently at 257pm, one minute before sunset.

How Much Solar Heating is there in Interior Alaska

Solar heating, or lack thereof, is a major driver in Interior Alaska. But why is it anymore (or less) important than anywhere else? Reader Trung has commented repeatedly about this. So, rather that spout some hand-wavy blather, let's deploy some actual physical modeling.



Here are some results using the Bird Clear Sky Model that produces quantitative estimates of solar radiation at the erath's surface using a variety of estimates of relevant variables (but with, not surprisingly, CLEAR skies). For this example I've left everything constant (e.g. albedo, water vapor). Using the spreadsheet from the National Renewable Energy Laboratory, I've summed the hourly values of global horizontal radiation, and then plotted the daily sums. The plots shows the huge annual variation at 65 (latitude of Fairbanks), from more than 8200 W/m² at summer Solstice to 12 W/m² at Winter Solstice (because these are the sums of the hourly values, these do not represent the total daily global horizontal radiation, but are computationally easier).

If we do exactly the same calculations, leaving all the variables the same except for latitude, at 40N we get 8700 W/m² at Summer Solstice to 2500 W/m² at Winter Solstice. So in the Summer Solstice, Fairbanks gets 94% of the solar heating as received at 40N, but at Winter Solstice Fairbanks 0.5% of what is received that day at 40N.

Put another way, at 40N, Winter Solstice receives about 29% of the heating received at Summer Solstice. In Fairbanks, Winter Solstice receives about 0.1% of the heating received at Summer Solstice.

So, I go on about solar heating (or lack thereof) because it varies so darn much over the year, far more than at mid-latitudes.

Cold Snow

About half an inch of snow and 28 below at 8am on Keystone Ridge. Here's how it snows at these cold temperatures. The morning sounding shows the deep cold air (-30C and colder) is about 400 meters thick. The snow producing clouds have a temperature around -20C to -23C. This is reflected in the sand-like consistency of the snow this morning.

Denali Sunrise

Sunrise late Sunday morning from Lake Minchumina, with Denali to the left (east) of the sun; image from the FAA webcam.

December 2011 and Annual Summary

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
1220 PM AKST SUN JAN 1 2012

...DECEMBER WEATHER SUMMARY FOR FAIRBANKS ALASKA...
...2011 WEATHER IN REVIEW...

THE FIRST THREE WEEKS OF DECEMBER WERE AMONG THE WARMEST EVER
RECORDED IN FAIRBANKS. THERE WERE EIGHT DAYS WHEN THE DAILY AVERAGE
TEMPERATURE WAS 20 OR MORE DEGREES ABOVE NORMAL. HOWEVER...THE
WEATHER TURNED SHARPLY COLDER RIGHT BEFORE CHRISTMAS AND THIS
CONTINUED THROUGH NEW YEARS EVE. THE LAST TWO DAYS OF THE MONTH
WERE MORE THAN 20 DEGREES COLDER THAN NORMAL.

OVERALL...THE AVERAGE HIGH TEMPERATURE AT THE AIRPORT WAS 14 ABOVE
AND THE AVERAGE LOW TEMPERATURE WAS 6 BELOW. THE MONTHLY AVERAGE
TEMPERATURE OF 4.0 ABOVE WAS MORE THAN 8 DEGREES WARMER THAN NORMAL
AND TIES WITH 1963 AS THE 10TH WARMEST DECEMBER IN 107 YEARS OF
OBSERVATIONS. IN THE PAST 20 YEARS ONLY DECEMBER 2002 WAS WARMER.
THE HIGHEST TEMPERATURE AT THE AIRPORT WAS 47 DEGREES ON THE 4TH.
THIS IS THE WARMEST TEMPERATURE EVER RECORDED IN FAIRBANKS DURING
DECEMBER EXCEPT FOR FIVE STRAIGHT DAYS IN DECEMBER 1934 WHEN HIGH
TEMPERATURES WERE IN THE 50S. THE LOW OF 36 BELOW OCCURRED ON THE
LAST TWO DAYS OF THE MONTH.

PRECIPITATION WAS WELL ABOVE NORMAL IN DECEMBER. A TOTAL OF 0.95
INCHES WAS MEASURED AT THE AIRPORT...WHICH IS ABOUT A THIRD OF AN
INCH ABOVE NORMAL...AND MAKES THIS THE WETTEST DECEMBER SINCE
1992. SNOWFALL TOTALED 12.2 INCHES...WHICH IS ALMOST EXACTLY
NORMAL. SNOW DEPTHS AT THE AIRPORT INCREASED FROM 7 INCHES ON THE
FIRST TO 14 INCHES ON THE 31ST. SNOWFALL WAS SUBSTANTIALLY HIGHER
TO THE NORTHWEST OF TOWN. THE GOLDSTREAM VALLEY BOTTOM COOPERATIVE
STATION MEASURED 16.9 INCHES OF SNOW...AND THE KEYSTONE RIDGE
STATION...NEAR MURPHY DOME...REPORTED 26.4 INCHES FOR THE MONTH.

DURING THE FIRST THREE WEEKS OF DECEMBER...IT WAS MUCH BREEZIER THAN
IS NORMAL IN FAIRBANKS IN MID-WINTER...TOPPED OFF BY STRONG WINDS
ON THE 4TH AND 5TH WHICH PEAKED AT 51 MPH...THE HIGHEST WIND GUST
OF RECORD IN DECEMBER IN FAIRBANKS. DURING THE COLD WEATHER LATE
IN THE MONTH...WINDS WERE NEARLY CALM.

LOOKING AHEAD TO JANUARY...THIS IS TYPICALLY THE COLDEST MONTH OF
THE YEAR IN FAIRBANKS. THE AVERAGE HIGH TEMPERATURE IS 1 ABOVE AND
THE AVERAGE LOW IS 17 BELOW. OVER THE PAST 108 YEARS...JANUARY
TEMPERATURES HAVE RANGED FROM A HIGH OF 52 ABOVE IN 2009 TO A LOW
OF 66 BELOW IN 1934. POSSIBLE SUNSHINE INCREASES FROM 4 HOURS ON
THE FIRST TO JUST UNDER 7 HOURS ON THE 31ST.

THE CLIMATE PREDICTION CENTER FORECAST FOR JANUARY IS FOR AN
INCREASED CHANCE FOR SIGNIFICANTLY BELOW NORMAL TEMPERATURES IN
FAIRBANKS.

OBSERVED LAST MONTH...12/2011

OBSERVED RANK
AVG MAX TEMP (F) 14.4 7TH WARMEST OF 107 YEARS
AVG MIN TEMP (F) -6.4 14TH WARMEST OF 108 YEARS
AVG TEMP (F) 4.0 10TH WARMEST OF 107 YEARS
TOTAL PRECIP (IN) 0.95 19TH WETTEST OF 97 YEARS


...WEATHER SUMMARY FOR 2011...

2011 WAS A MEMORABLE YEAR WEATHER-WISE IN FAIRBANKS. LATE FEBRUARY
BROUGHT TWO MAJOR STORMS THAT WERE...MOST UNUSUALLY...ACCOMPANIED
BY STRONG WINDS AND EVEN SOME BLOWING SNOW. THE STORM ON FEBRUARY
20 AND 21ST BROUGHT A WHOPPING 17.1 INCHES OF SNOW IN 24 HOURS...
THE SECOND HIGHEST 24 HOUR SNOWFALL EVER MEASURED IN FAIRBANKS.
THE SPRING WAS EXTREMELY DRY...AND SOME OF THE WARMEST WEATHER
EVER RECORDED IN MAY OCCURRED LATE THAT MONTH. THE WARM AND DRY
CONDITIONS CONTRIBUTED TO THE MOOSE MOUNTAIN AND HASTING FIRES
THAT STARTED IN LATE MAY. THE REST OF THE SUMMER BROUGHT A
GENERALLY QUIET FIRE SEASON. THE AUTUMN WAS PERSISTENTLY MILD
UNTIL MID- NOVEMBER...WHEN THE COLDEST SUSTAINED WEATHER OF RECORD
BEFORE THANKSGIVING GRIPPED THE AREA...ONLY TO BE FOLLOWED BY THE
EXTREME WARMTH OF THE FIRST THREE WEEKS OF DECEMBER. OVERALL...THE
AVERAGE TEMPERATURE FOR THE YEAR OF 27.9 DEGREES WAS ALMOST
EXACTLY NORMAL. THE HIGH FOR THE YEAR WAS 88 DEGREES ON JUNE 25TH.
THE LOW WAS 44 BELOW ON FEBRUARY 15TH. THE TOTAL PRECIPITATION OF
9.54 INCHES WAS ABOUT 12 PERCENT BELOW NORMAL.

$$
RT/JM JAN 12

First 40 below of the Cold Snap

Through 11am AST the low temperature at the Fairbanks airport has been 43 below. This is the first 40 below of this cold snap at the Airport. Eielson AFB has been down to 45 below.

Updated:

53 below at McGrath, Galena, Huslia, Nikolai, Kaltag, Tanana and Manley Hot Springs