Chena Slush Out

Here's a somewhat fuzzy webcam photo looking south across the Chena River just before 8pm ADT Thursday from Front Street (image courtesy of Pro Music). There are some open areas but most of the water visible is water on top of ice.

AO and Alaska Temperatures

A reader asked if the yo-yo temperatures since last autumn are related to the Arctic Oscillation. Short answer, no.

Long answer:

For starters, the Arctic Oscillation Index is a way to describe (near) surface pressure patterns in the Northern Hemisphere at mid and high latitudes. However, as the plot below illustrates, the long term (1949-2012) correlation with surface temperatures in the cold season (Oct-Mar) are not very high over western North America and most of Alaska (the correlation is marginally significant over a small area over south-central Alaska).



For this past cold season, below is a plot of the daily AO index and the standardized daily mean temperature anomaly for Fairbanks (through April 13). As you can see, there was no patterning of the AO Index with how much above or below normal the temperature was in Fairbanks. Notice that the very cold weather in mid-November occurred with a somewhat positive AO, while the cold weather at the end of January occurred when the AO was at largest negative value of the whole winter. Similarly, the very mild weather in early December occurred with a strongly positive AO, while at the end of December the AO was again strongly positive but Fairbanks was considerably colder than normal. For the whole period (Oct 1-Apr 13), the correlation was functionally zero (0.02).

New Webcam

Yahoo! The FAA's webcam high atop Ester Dome, northwest of UAF, is finally online. Here's the southeast view from 418pm ADT Wednesday. There are also views looking north, southwest and west. You can plainly see Chena Ridge and the Tanana River.

Snowpack Meltout

With record heat in progress, and the snow depth down to 7 inches and going fast, here's a look at the winter snowpack meltout date since 1930. For this exercise, meltout date is the latest date with 1 inch or more snow on the ground which was preceded by a week of days with an inch or more of snow on the ground. This last bit is there to exclude the few years like, say, 2001, when the winter snowpack was gone by April 22nd, but there were two consecutive days with accumlating snow in early May that resulted in an inch on the ground on the morning of May 5th. For most of the period of record, this is the depth of snow on the ground early in the morning. The plot on the right shows this date for each year through 2011; the black line is the 5-year running mean. As you can see, since 1972 the winter snowpack has lasted into May only four times, though since the early 1970s there is no trend at all in meltout dates.

Meltout date this year will be April 17-19, so just a touch earlier than the long term average.

Hot April Heads-Up

The average temp the first half of April in Fairbanks was 30.1F, which is 3.0F above normal. Left is the updated plot of standardized daily mean temp departures for 2012, with the current warmth falling right in with yo-yo pattern we had all winter.

The 90% percentile April mean temps for Fairbanks (1905-2011 data) is 36.9F. In order for this month to make the top 10% warmest Aprils, the second half of the month would have to have a mean temp of 43.7F, which is 5.7F above normal for April 16-30th.

That's a tall order, but with the valley snowpack now going fast and the CFS and CPC weeks 1 and 2 guidance showing no end to the warmth, it looks to be within reach. Of course, six of the ten warmest Aprils of record have occurred since 1990.

Temperature Differences

Measuring the temperature of the air seems like a simple thing, but in fact getting an accurate measure is actually not so trivial. For meteorological/cimatological purposes we of course want to keep the sensor out of the sun (because we're interested in the temperature of the air, not the temperature of the thermometer). This is done by enclosing the thermometer (or temperature sensor) in some kind of enclosure. But you want to keep the air moving through the enclosure, otherwise the mere fact that there is an enclosure will impact the temperature of the air inside.

So, there are basically two approaches used. First, have a fan move air from outside the enclosure across the thermometer and then out, or design you enclosure so that air can move freely through. The fan approach is termed aspirated, the second is termed passive. Usually there is not not much difference, but conditions this week, with brilliant sunshine, a still solid snow cover and not much wind are producing small but consistent differences. The graphic above shows the high temperatures on Wednesday. As you would expect, aspirated sensors run a little bit cooler.

First 50F of the Year

Updated: The high temperature at the airport was 51F.

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
426 PM AKDT TUE APR 10 2012

...HIGH TEMPERATURE HITS 50 DEGREES IN FAIRBANKS....
...FIRST 50 DEGREE DAY OF THE YEAR...

THE TEMPERATURE AT THE FAIRBANKS INTERNATIONAL AIRPORT ROSE TO 50
DEGREES AT 330PM TUESDAY AFTERNOON. THIS IS THE WARMEST IT HAS BEEN
THIS YEAR AND IS FIRST TIME THE TEMPERATURE HAS BEEN AS HIGH AS 50
DEGREES SINCE OCTOBER 14TH.

OVER THE PAST 80 YEARS...THE AVERAGE DATE OF THE FIRST 50 DEGREE
OR HIGHER TEMPERATURE IN THE SPRING IN FAIRBANKS IS APRIL 10TH.

$$
RT APR 12

Spring time Inversion

Clear skies overnight and a still solid snowpack helped a reasonably strong inversion to form overnight. Valley min temperatures were in the lower teens while higher elevations barely got below freezing. Some specific low temperatures include:

Goldstream Creek: 10F
Chena Hot Springs: 11F
Woodsmoke PWS: 13F (near North Pole)
Fairbanks Airport: 14F

Keystone Ridge: 29F
Nenana Hills RWIS: 31F
Cleary Summit RWIS: 32F

Sunny Sunday

View from the Keystone Ridge weather station on Sunday, looking east. Snow depth is at 28 inches. We've not completely lost the snow cover in April any time snow depth has been two feet or more on April 8th.

Anchorage Sets Snowfall Record

After much adieu…


PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE ANCHORAGE AK
740 PM AKDT SAT APR 7 2012

UPDATED WITH LATEST SNOW TOTAL

...ANCHORAGE SETS NEW SEASONAL SNOWFALL RECORD...

SNOW HAS TAPERED OFF TO FLURRIES AT THE NATIONAL WEATHER SERVICE
FORECAST OFFICE AND NO ADDITIONAL ACCUMULATION IS EXPECTED FROM
THIS STORM. AN ADDITIONAL 0.9 INCHES OF SNOW FELL BETWEEN 4 PM
AND 7 PM WHICH BRINGS THE TOTAL FOR THE DAY TO 4.3 INCHES.

THIS MAKES THE 2011-2012 WINTER SEASON THE SNOWIEST EVER WITH
A TOTAL OF 134.5 INCHES. THE PREVIOUS SEASONAL SNOWFALL RECORD
WAS 132.6 INCHES SET IN 1954-1955.

$$

SEB/CC

it's a Hot One

Yesterday was the warmest day since early October in Fairbanks-land. Some high temperatures included:

Woodsmoke: 50F (near North Pole)
Fairbanks Airport: 49F
Fort Wainwright: 49F
Goldstream Creek: 49F
Eielson AFB: 48F
Keystone Ridge: 45F

Fairbanks March Summary

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
244 PM AKDT SUN APR 1 2012

...MARCH WEATHER SUMMARY FOR FAIRBANKS...
...COLD AND SNOWY...

FOLLOWING A VERY MILD FEBRUARY...THE WEATHER PATTERN OVER NEARLY
ALL OF ALASKA FLIPPED...AND MOST AREAS HAD WELL BELOW NORMAL
TEMPERATURES FOR MOST OF MARCH. FAIRBANKS WAS NO EXCEPTION.

THE AVERAGE TEMPERATURE OF 4.5 ABOVE WAS NEARLY SEVEN DEGREES
COLDER THAN NORMAL AND RESULTED IN MARCH...QUITE UNUSUALLY...BEING
COLDER THAN FEBRUARY. AS WAS THE CASE IN JANUARY...DAILY
TEMPERATURES WERE NOT EXCESSIVELY LOW...AS THERE WERE NO
TEMPERATURES EVEN CLOSE TO RECORD LEVELS. RATHER...THE PERSISTENCE
OF CHILLY TEMPERATURES WAS MOST NOTABLE. EVERY DAY BUT ONE FROM
THE 10TH THROUGH THE 23RD WAS TEN OR MORE DEGREES COLDER THAN
NORMAL.

FOR THE MONTH...THE AVERAGE HIGH TEMPERATURE AT THE AIRPORT WAS
18 ABOVE AND THE AVERAGE LOW WAS 9 BELOW. THE TEMPERATURE ROSE
ABOVE FREEZING FOR THE FIRST TIME SINCE BEFORE CHRISTMAS ON THE
27TH...AND THE HIGH FOR THE MONTH WAS 44 DEGREES ON THE 28TH. THE
LOW TEMPERATURE IN MARCH WAS 30 BELOW ON THE 5TH...WHICH IS VERY CLOSE
TO THE LONG TERM AVERAGE LOWEST TEMPERATURE IN MARCH. THERE WERE
EIGHT DAYS WITH LOWS OF 20 BELOW OR LOWER...A BIT MORE THAN IN AN
AVERAGE MARCH.

MARCH IS TYPICALLY A DRY MONTH IN FAIRBANKS...BUT NOT THIS YEAR.
TOTAL SNOW OF 14.7 INCHES AT THE AIRPORT MADE THIS THE THIRD
SNOWIEST MARCH IN THE PAST 45 YEARS. MOST OF THE SNOW CAME ON THE
5TH THROUGH 7TH...WHEN SOME PLACES NORTH AND EAST OF TOWN RECEIVED
MORE THAN 18 INCHES OF SNOW. THE SNOW WAS QUITE POWDERY...WHICH IS
USUAL FOR THIS TIME OF YEAR. THIS BROUGHT THE SEASONAL TOTAL
SNOWFALL UP TO 57.4 INCHES...ABOUT 4 INCHES BELOW NORMAL. THE SNOW
DEPTH REACHED 29 INCHES ON THE 8TH...THEN COMPACTED TO 22 INCHES
BY THE 31ST.

SOME PRECIPITATION FELL ON MORE THAN HALF THE DAYS IN MARCH. THE
SNOW MELTED DOWN TO 0.74 INCHES OF WATER...NEARLY THREE TIMES
NORMAL.

LOOKING AHEAD TO APRIL...NORMAL TEMPERATURES CONTINUE TO INCREASE
RAPIDLY. AVERAGE HIGH TEMPERATURES RISE FROM 35 DEGREES ON THE FIRST
TO 54 DEGREES IN THE 30TH. APRIL IS OFTEN QUITE DRY. IN THE PAST
20 YEARS...HALF THE APRILS HAD LESS THAN ONE TENTH OF INCH OF
PRECIPITATION. MOST OF WHAT DOES FALLS TYPICALLY FALLS AS
SNOW...THOUGH RAIN SHOWERS SOMETIMES OCCUR...ESPECIALLY THE SECOND
HALF OF THE MONTH. ON RARE OCCASIONS SIGNIFICANT SNOWFALL OCCURS
IN APRIL...THOUGH ONLY FIVE APRILS IN THE PAST 60 YEARS HAVE
RECEIVED MORE THAN 10 INCHES OF SNOW. THE WINTER SNOWPACK USUALLY
MELTS OUT IN TOWN DURING APRIL. THE AVERAGE DATE FOR LAST DAY WITH
AN INCH OR MORE OF SNOW ON THE GROUND IS APRIL 22ND.

APRIL IS OFTEN A SUNNY MONTH...AS POSSIBLE SUNSHINE INCREASES FROM
13 HOURS AND 41 MINUTES ON THE FIRST TO 17 HOURS ON 30TH. DURING
THE LAST WEEK OF APRIL...SOME TWILIGHT REMAINS VISIBLE IN NORTHERN
SKY ALL NIGHT LONG.

$$
RT APR 12

Springtime in Alaska

A lovely April 1st at Denali National Park. Headquarters has a snow depth of 25 inches...which is pretty close to normal. Webcam photo from the FAA.

An Unexpected Snow

A quick couple inches of snow this morning in parts of Fairbanks-land, though from North Pole southward there was very little. Webcam photo from the Alaska Climate Research Center on UAF West Ridge from around noon with the sun poking through the clouds.

Spring up North

It's been a cold March on the North Slope: though Monday the average monthly temperature at Barrow was about 9 degrees below normal. And this morning continues that trend. Here's a photo from Barrow (UAF Sea Ice webcam), with the school bus trundling along through a brisk -29F morning. Elsewhere on the Slope (through 7am ADT), lows include 43 below at Nuiqsut and Umiat, 42 below at Deadhorse Airport and 37 below at Atqasuk.

Temperature Anomolies

With more seasonable temperatures in place now, here's an update of the standardized daily anomalies this winter for Keystone Ridge through Friday. What a see-saw season it's been.

Winter Lives, Sort Of

A fresh injection of cold air sent temperatures falling in Fairbanks-land overnight, and in valley where the wind dropped off it was kind of like winter. Lows included:

Goldstream Creek: 24 below
Fort wainwright RAWS: 23 below
Eielson AFB: 17 below

Elsewhere in the Interior:
Beaver Creek RAWS: 30 below
Eagle Coop: 28 below
Toklat RAWS: 24 below

(Image from Arctic Village, 925am Wednesday, courtesy of the FAA)

Solar Spring is Here

Here's a plot of daily high temperatures over the past five weeks at Fairbanks Airport (475 feet MSL) and Keystone Ridge (1600' MSL). The green line is the difference between the two (Airport minus Ridge). Up through late February, high temperatures were consistently lower at the Airport than on the Ridge. Since the end of February, the rapidly increasing solar insolation is breaking the nocturnal temperature inversion almost every day now, and this is a useful definition of spring in Interior Alaska.

Still Chilly on the Slope

It's been a cold week on the North Slope. Lows Thursday morning include:

Nuiqsut: -47F
Umiat: -47F
Sagwon SnoTel: -46F
Deadhorse Airport: -45F
Ikpikpuk River: -45F
Otuk Creek: -44F
Camden Bay: -41F

Swinging Temperature Update

Here's an update showing mean daily temperatures and standardized departures for Fairbanks since October 1st. The alternating cycle of warm-cold looks to continue.

Nippy on the North Slope

Temperatures are in the 40s below on parts of the North Slope Saturday morning, along with a fresh breeze in some places. At 8am AST,

Nuiqsut: -48F, south wind 9 mph
Alpine: -45F, south wind 9 mph
Deadhorse: -45F, southwest wind 13 mph

While plenty cold, this is not all that unusual this time of year for the North Slope.

Photo from Umiat at 8am, at a brisk -43F.

Snow update

This photo gives an idea of the snowfall here in the past 36 hours.

Through 9am Wednesday, 23.1 inches of snow here at Keystone Ridge since 6pm Monday. The maximum 24 hour total was 18.7 inches, 10pm Monday to 10pm Tuesday, by far the highest 24 hour amount in the 16 years here on the hill. This also pushes the seasonal total up over 100 inches.

Other event total snowfalls include

14 Mile Chena Hot Springs Road: 14.9"
Goldstream Creek: 13.5"
College Hills 12.5"
UAF West Ridge: 11.0"
Woodsmoke 8.6" (through 10pm Tuesday)
Fairbanks Airport: 8.6" (through midnight Tuesday night)

I'll update as more observations arrive.

Snow update

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
844 PM AKST TUE MAR 6 2012

...HEAVIEST SNOWFALL OF THE WINTER IN FAIRBANKS...

FAIRBANKS RECEIVED ITS HEAVIEST SNOWFALL OF THE SEASON SO FAR
YESTERDAY AND TODAY. AS OF 3PM TUESDAY...FAIRBANKS INTERNATIONAL
AIRPORT RECEIVED AN OFFICIAL STORM TOTAL OF 7.4 INCHES OVER THE
COURSE OF LESS THAN 24 HOURS...AND THE SNOW HAS BEEN CONTINUING TO
FALL THROUGHOUT THE EVENING.

HERE ARE A FEW STORM TOTALS SO FAR FROM SPOTTERS AROUND THE AREA
AS OF 8PM:

KEYSTONE RIDGE........................16.6 INCHES
14 MILE CHENA HOT SPRINGS ROAD........11.3 INCHES
GOLDSTREAM CREEK......................10.8 INCHES
COLLEGE HILLS..........................9.9 INCHES
UAF WEST RIDGE.........................9.1 INCHES
HAMILTON ACRES.........................8.5 INCHES
WOODSMOKE/NORTH POLE...................7.7 INCHES

SNOW SHOWERS WILL CONTINUE THROUGH TUESDAY NIGHT WITH ANOTHER 1 TO 3
INCHES EXPECTED THROUGH 9AM WEDNESDAY. SNOW IS EXPECTED TO TAPER OFF TO
FLURRIES BY MID MORNING WEDNESDAY.

$$

JM

Snow Update

As of 6pm AST Tuesday, there has been 15.6" of snow since 6pm Monday here at Keystone Ridge. This is the greatest 24 hour snow total in the 16 years of obs here. Occasional gusty winds, but no significant drifting today, even in open areas. Snow occasionally blowing off of trees in exposed areas. That's a lot of shoveling.

Chamber of Commerce Day in Barrow

Lovely early spring day in Barrow: sunny, 19 below, west wind 10 mph. Image courtesy of the UAF Sea Ice Group.

Fluff Storm

Powdery snow overnight in Fairbanks-land

So far, amounts include
Keystone Ridge: 9.8"
UAF West Ridge: 6.2"
Goldstream Creek: 5.0"

All these locations have snow-liquid ratios of 20-30 to one, which is very high for around a quarter inch of liquid.

Big Snowfall Differences

Here's a plot of cumulative seasonal snowfall (through March 03) for Keystone Ridge and the Fairbanks Airport. The snowfall on the ridge is close to normal; the airport is only about 77% of normal. This is the biggest difference between the two sites in the 16 years of observations on the Ridge. The NRCS snow course data for March 1st is dribbling in, and shows that the below normal snowfall is confined to an area from Fairbanks eastward into the upper Chena and Salcha Basins, while north and west of Fairbanks, snowfall is close to or even a bit above normal.

Same Old Story

Here's the standardized daily temperature departures for Keystone Ridge for this winter. The pattern continues.

Winter 2011-2012

Here's another chart of the roller coaster temperatures in Fairbanks winter 2011-2012.

February Summary

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
159 AM AKST THU MAR 1 2012

...MONTHLY WEATHER SUMMARY FOR FAIRBANKS ALASKA...

IN A DRAMATIC TURN AROUND FROM JANUARY...FAIRBANKS TEMPERATURES
IN FEBRUARY WERE PERSISTENTLY MILDER THAN NORMAL. HALF
THE DAYS DURING THE MONTH HAD AN AVERAGE DAILY TEMPERATURE
10 DEGREES OR MORE ABOVE NORMAL...WHILE ONLY THREE DAYS WERE 10 OR
MORE DEGREES COLDER THAN NORMAL. THIS WAS THE MILDEST FEBRUARY IN
FAIRBANKS SINCE 2002.

OVERALL..THE AVERAGE HIGH TEMPERATURE AT THE FAIRBANKS AIRPORT WAS
17 ABOVE AND THE AVERAGE LOW WAS 5 BELOW. THE AVERAGE TEMPERATURE
FOR THE MONTH OF 5.9 ABOVE WAS 7.2 DEGREES WARMER THAN
NORMAL...AND A WHOPPING 32.7 DEGREES WARMER THAN THAN AVERAGE
TEMPERATURE IN JANUARY. ONLY ONCE...IN 1934...WAS A JANUARY TO
FEBRUARY AVERAGE TEMPERATURE INCREASE GREATER THAN THIS YEAR.

THE HIGH TEMPERATURE IN FEBRUARY AT THE AIRPORT WAS 31 DEGREES ON
THE 5TH AND THE LOW OF 35 BELOW OCCURRED ON THE 1ST. TEMPERATURES
DID CREEP A BIT ABOVE FREEZING IN PARTS OF THE AREA...ESPECIALLY
ON THE 9TH AND 10TH...INCLUDING 35 DEGREES AT NORTH POLE AND
37 DEGREES AT UAF WEST RIDGE.

SNOWFALL WAS NEAR NORMAL IN FEBRUARY...WITH 7.5 INCHES AT THE
AIRPORT. THIS MELTED DOWN TO 0.42 INCHES OF WATER...WHICH IS
EXACTLY NORMAL. SNOW DEPTHS VARIED THROUGH THE MONTH BETWEEN 18
AND 21 INCHES.

WINDS WERE CHARACTERISTICALLY LIGHT AT THE AIRPORT...AVERAGING
ONLY 2.3 MPH. THE PEAK WIND OF 23 MPH OCCURRED ON THE 2ND.

FOR THE MID-WINTER PERIOD...DECEMBER THROUGH FEBRUARY...LARGE
TEMPERATURE SWINGS WERE THE RULE...WHICH ALMOST COMPLETELY
BALANCED OUT. THE FIRST THREE WEEKS OF DECEMBER WERE THE WARMEST
OF RECORD. THE LAST DAYS OF DECEMBER UNTIL THE FIRST OF FEBRUARY
WERE CONSISTENTLY QUITE COLD...FOLLOWED BY MILD WEATHER MOST OF
FEBRUARY. THE AVERAGE TEMPERATURE FOR THE THREE MONTHS AT THE
AIRPORT OF MINUS 5.9 DEGREES WAS ABOUT 1.5 DEGREES BELOW NORMAL.
SNOWFALL FOR THE THREE MONTHS WAS VERY CLOSE TO NORMAL...BUT FOR
THE SEASON THE TOTAL SNOW OF 42.7 INCHES IS MORE THAN A FOOT BELOW
NORMAL DUE TO THE LOW SNOWFALL IN THE AUTUMN.

LOOKING AHEAD TO MARCH...RAPIDLY INCREASING SUNSHINE HELPS BOAST
TEMPERATURES. AVERAGE DAILY HIGH TEMPERATURES INCREASE FROM
18 DEGREES ON THE 1ST TO 34 DEGREES ON THE 31ST. AVERAGE LOW
TEMPERATURES INCREASE FROM 9 BELOW ON THE 1ST TO 8 ABOVE ON THE
31ST. IN THE PAST 105 YEARS...TEMPERATURES HAVE RANGED FROM A HIGH
OF 56 DEGREES IN 1994 TO A LOW OF 56 BELOW IN 1911. SNOWFALL IS
TYPICALLY LIGHT...AVERAGING LESS THAN 5 INCHES...AND HAS EXCEEDED
A FOOT ONLY TWICE IN THE PAST 40 YEARS. POSSIBLE SUNSHINE
INCREASES FROM JUST OVER 10 HOURS ON THE FIRST TO 13 AND ONE HALF
HOURS ON THE 31ST. THE FORECAST FOR MARCH FROM NOAA'S CLIMATE
PREDICTION CENTER CALLS FOR AN INCREASED CHANCE OF SIGNIFICANTLY
BELOW NORMAL TEMPERATURES FOR FAIRBANKS.

Closing Up Winter

Here's a plot of the daily average temperature at Fairbanks since Oct 01. For what I usually refer to as "mid-winter", December through February, the mean temperature (through Feb 27) of -6.0F is a bit below normal (-4.7F through Feb 27). This will be coldest December through February since, get this, way back in 2008-09.

Wild Swings Update

Here's the updated plot of standardized daily temperature departures for this winter (through Feb 24) at Fairbanks. While not extreme this month, the persistent warmth follows the pattern established in November.

Arctic Sea Ice

Arctic sea ice is within a few weeks of it's maximum extent. Here is the Alaska-centered view from the University of Illinois's Cryosphere Today:

http://arctic.atmos.uiuc.edu/cryosphere/

Sea ice extent is much above normal, while on the European side of the Arctic it's much below normal.

Nice February Day

A lovely late February day at Arctic Village: sunny and 13 below at 1pm

Fluffy Snow

Keystone Ridge through noon Wednesday: 1.4inches of snow melted down to 0.03" water. Snow so fluffy you can see through it. :)

Another Morning, Another Inversion

Here's the morning sounding from Fairbanks, showing a strong inversion. At 9am, Goldstream Creek was -14F and Keystone Ridge +20F. Solar heating is increasing rapidly but is still not enough to come close to breaking the inversion. Yesterday the high temperature at Fairbanks was +11F, ten degrees lower than on Keystone Ridge.

More on the Wild Temperature Swings

The monthly mean temperature in January at the Fairbanks Airport was 30.8F lower than the December mean, This is the largest drop between December and January in the Weather Bureau/NWS era (since 1930). The change from October to November, 2011 of -37.1F was the third greatest since 1930. Depending on how the rest of this month turns out, it is entirely possible that the change from January to February will be in the top five greatest increases.

Clear Skies at Night, an Inversion's Delight

Clear skies overnight have allowed a strong inversion to develop this morning. At 8am, -10F in Goldstream Creek and +24F here on Keystone Ridge.

How Warm Has it Been?

The average temperature at the Fairbanks Airport the first two weeks of February was +5.6F. This is about 10 degrees above normal, but is only the 17th warmest first half of February of record. Temperatures are not expected to show overall much change the next few days, though low temperatures will vary in valleys depending on overnight cloud cover.

February Sunrise

A pretty morning Thursday at Mentasta Pass on the Glenn Highway, south of Tok. Photo from the FAA webcam.

Wicked Inversion

Here's the 3am AST Monday sounding from Fairbanks Airport, showing a very sharp surface inversion. That's a temperature of +4F at ground level, and +32F just 32 meters up. At 8am AST, the temperature at Goldstream Creek was -5F, while most of the hill elevation sites were reporting temperatures near +30F.

The Yoyo Goes On

Now that the next "warm phase" of the winter is well underway for Interior Alaska, here's an updated plot of standardized daily temperature anomalies at Fairbanks. For the most part, it's been either one or the other. Since November 1st, 54% of the days (55 out of 102) days have had an average daily temperature 1.0 or more standard deviations from the mean. If temperatures were normally distributed (which in general is not the case), we would expect about 32 such days. In the El Niño winter of 2009-10, Nov 1-Feb 10 had only 24 days ±1.0 standard deviation from the daily normal. Got all that?

The Carved Out Ridge

Here's the Monday 11am AST GOES-15 infrared image. This nicely show the high aloft centered over the Yukon (with a small low embedded near Watson Lake).

As the Winter Turns

Here's an updated plot of daily average temperatures this winter at Fairbanks. The mild weather now in place will be modulated in the valley by strong inversions when skies stay clear and winds stay light, at for the next couple of days. At 11am Monday, temperatures are near zero in the valleys and just above freezing at higher elevations. And the sun is shining.

Cold Snap at an End

Cold Snap 2012 has come to an end, with nearly all of northern Alaska now above zero. Here's a UCAR plot of observations from 11am AST Sunday. The only large area still below zero is the western North Slope. There is a typical inversion over much of the Interior. At 11am in the Fairbanks area temperatures were in the single digits above zero, while higher elevations were in the upper 20s and lower 30s.

Big Swings

Here's a plot of hourly temperatures at Keystone Ridge since Wednesday. Find the time of frontal passage. The drop from 25F at 8pm to -1F at 10pm was accompanied by only a slight breeze: enough to tinkle the wind chimes, but that's about it.

January Cold Stats

Here's an abridged version of the statement highlighting the monthly records. The full version (for a while) is here.

NOAK49 PAFG 012052
PNSAFG
AKZ216-218>225-227-020915-

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
1146 AM AKST WED FEB 1 2012

...JANUARY 2012 WAS A RECORD OR NEAR RECORD COLD MONTH FOR MUCH OF
CENTRAL AND WESTERN ALASKA...

ALL OF NORTHERN ALASKA WAS UNDER THE INFLUENCE OF A VERY COLD AIR
MASS FOR NEARLY ALL OF JANUARY. THE GREATEST TEMPERATURE DEPARTURES
FROM NORMAL OCCURRED ACROSS THE WESTERN INTERIOR WHERE THE SKY WAS
MORE PERSISTENTLY CLEAR...WHICH ALLOWED STRONG INVERSIONS TO FORM
AND TEMPERATURES REMAINED VERY LOW FOR A PROLONGED PERIOD OF TIME.
MANY COMMUNITIES ALONG THE WEST COAST AND ACROSS THE WESTERN
INTERIOR HAD THE COLDEST OR ONE OF THE TOP FEW MONTHS ON RECORD.
THE DURATION OF THE COLD WEATHER WAS MORE NOTABLE THAN THE
ABSOLUTE MINIMUMS...AS RELATIVELY FEW DAILY RECORD LOW TEMPERATURES
WERE SET AT LOCATIONS WITH MORE THAN 50 YEARS OF WEATHER
OBSERVATIONS.

AT NOME...THIS PAST JANUARY WAS THE COLDEST ON RECORD. THE
AVERAGE TEMPERATURE OF -16.6 DEGREES EASILY EXCEEDED THE OLD
RECORD OF -15.2 DEGREES THAT OCCURRED IN 1989. THIS WAS NOT QUITE
THE COLDEST MONTH OF RECORD...AS FEBRUARY 1990 HAD AN AVERAGE
TEMPERATURE OF -17.2 DEGREES. FOR COMPARISON...THE NORMAL
TEMPERATURE FOR NOME DURING JANUARY IS 5.2 DEGREES ABOVE ZERO. THE
LOWEST TEMPERATURE OBSERVED DURING THE MONTH WAS 40 BELOW ON THE
5TH. THIS WAS THE FIRST 40 BELOW READING AT NOME SINCE 1999.
TEMPERATURE RECORDS AT NOME DATE BACK TO 1907.

AT KOTZEBUE...JANUARY 2012 WAS THE SECOND COLDEST SINCE 1929. THE
AVERAGE TEMPERATURE OF -22.6 DEGREES IS THE COLDEST SINCE 1934...
WHEN THE AVERAGE TEMPERATURE WAS -27.7 DEGREES. CONTINUOUS
TEMPERATURE RECORDS AT KOTZEBUE DATE BACK TO 1929. THE LOW
TEMPERATURE OBSERVED DURING THE MONTH OCCURRED ON THE EVENING OF
THE 31ST WITH A LOW OF 45 BELOW. THIS WAS THE COLDEST TEMPERATURE
OBSERVED AT KOTZEBUE SINCE 2006.

AT GALENA...JANUARY 2012 GOES DOWN AS THE COLDEST MONTH OF
RECORD. THE AVERAGE TEMPERATURE OF -32.6 DEGREES SURPASSED THE
-31.4 DEGREES IN 1971. THE LOWEST TEMPERATURE THIS MONTH WAS 65 BELOW
OBSERVED ON THE 29TH. NOT ONLY WAS THIS A DAILY RECORD LOW...BUT
IT WAS THE 3RD LOWEST TEMPERATURE EVER OBSERVED AT GALENA. THE
ALL-TIME LOW WAS 70 BELOW BACK IN JANUARY 1989. THERE WERE ALSO
FOUR CONSECUTIVE DAYS WITH A LOW TEMPERATURE OF 60 BELOW OR COLDER
ON THE 28TH THROUGH THE 31ST. THIS WAS ONLY OUTDONE ONCE...IN
1989...WHEN THERE WERE SIX CONSECUTIVE 60 BELOW DAYS AT GALENA.
WEATHER RECORDS AT GALENA DATE BACK TO 1942.


AT MCGRATH...THE AVERAGE TEMPERATURE OF -28.5 IS THE COLDEST MONTH
OF RECORD. THE PREVIOUS RECORD WAS -27.5 DEGREES IN JANUARY 1989.
THE LOW TEMPERATURE IN JANUARY WAS 55 BELOW ON THE 4TH. WEATHER
OBSERVATIONS HAVE BEEN MADE AT MCGRATH SINCE 1939.

AT BETTLES...THIS PAST JANUARY ENDED UP AS THE COLDEST ON RECORD.
THE AVERAGE TEMPERATURE OF -35.6 DEGREES SURPASSED THE OLD RECORD
OF -34.0 IN 1971. THE LOW TEMPERATURE FOR THE MONTH WAS 61 BELOW
ON THE 31ST. THREE OF THE LAST 4 DAYS OF THE MONTH HAD A LOW
TEMPERATURE OF 60 BELOW...AND ALL THREE WERE NEW DAILY
TEMPERATURE RECORDS. THESE WERE THE FIRST 60 BELOW TEMPERATURES AT
BETTLES SINCE FEBRUARY 1999. WEATHER RECORDS AT BETTLES DATE BACK
TO 1951.

AT TANANA...THIS PAST JANUARY WAS THE COLDEST IN OVER A HUNDRED
YEARS WITH AN AVERAGE TEMPERATURE OF -32.6 DEGREES. ONLY 1906 WITH
AN AVERAGE TEMPERATURE OF -36.6 DEGREES WAS ANY COLDER. THE LOW
TEMPERATURE FOR THE MONTH OF 61 BELOW WAS OBSERVED ON THE 28TH.
ALTHOUGH NOT A RECORD...IT WAS THE FIRST TIME THE TEMPERATURE HAD
DROPPED TO 60 BELOW OR LOWER SINCE 1993.

AT DENALI NATIONAL PARK HEADQUARTERS...THIS WAS THE COLDEST
JANUARY SINCE 1933...WITH AN AVERAGE TEMPERATURE OF -18.6 DEGREES
AND IS 22 DEGREES BELOW NORMAL. THE LOWEST TEMPERATURE WAS 41 BELOW
ON THE 25TH. WEATHER OBSERVATIONS HAVE BEEN MADE AT DENALI
NATIONAL PARK HEADQUARTERS SINCE DECEMBER 1922.

AT FAIRBANKS...JANUARY 2012 WAS THE FIFTH COLDEST ON RECORD WITH AN
AVERAGE TEMPERATURE OF -26.9 DEGREES...WHICH WAS 19 DEGREES BELOW
NORMAL. IT WAS THE COLDEST JANUARY AT FAIRBANKS SINCE 1971...AND
RANKED ONLY BEHIND 1906...1934...1966 AND 1971. THE COLDEST
TEMPERATURE OBSERVED WAS 51 BELOW ON THE 29TH. TEMPERATURE RECORDS
AT FAIRBANKS START IN SEPTEMBER 1904.

EAST OF THE FAIRBANKS AREA THIS WAS GENERALLY ONLY THE COLDEST
JANUARY SINCE 2004, AND ON THE NORTH SLOPE...TEMPERATURES IN JANUARY WERE CONSIDERABLYBELOW NORMAL BUT WERE NOWHERE NEAR RECORD COLD.

$$
CB/RT FEB 12

The Way Cold Snaps End

Furiously warming aloft since mid-day Tuesday. The morning sounding tells the story. At 6am Wednesday, Cleary Summit+3F, Fairbanks Airport -34F

Pattern Change Coming

I'll have a lot to say about the cold January stats, but in the meantime, a big, big change is on the way. Here's the Canadian GEM forecast valid Sunday morning, showing a big ridge aloft from British Columbia northwest in Interior Alaska. This is will a very mild pattern, though strong inversions will sometimes mask the warm airmass in valley bottoms.

Satellite Temperatures

Nice post today from the University of Wisconsin CIMSS blog on satellite derived temperatures over the past couple days in Interior Alaska.

http://cimss.ssec.wisc.edu/goes/blog/archives/9672

Slowwww Warming

Here's the plot of low level temperatures from Fairbanks. It continues to oh so slowly warm aloft. At 10am AST, Cleary Summit was up to -16F, and at 11am here on Keystone Ridge it was -22F. Meanwhile, at 11am, -50F at Fairbanks International.

More Cold

Updated:
Cooperative observations in the past 12 hours add more definition to the cold:

Low temperatures Saturday include:
Galena: -63F (cooperative observer, new record for date)
Clear Sky Lodge: -60F (on the Parks Highway near Anderson)
North Pole: -57F (cooperative observer)
Woodsmoke: -57F (near North Pole; cooperative observer)
Goldstream Valley Bottom: -55F

Low temperatures Sunday morning include:
Fort Yukon: -65F (cooperative observer)
Kandik River: -64F (cooperative observer)
Manley Hot Springs: -60F
Bettles: -60F (new record for date)
Chicken: -59F
Circle Hot Springs: -58F
Eagle: -57F (cooperative observer)
Goldstream Creek: -55F
Nenana: -54F
Eielson AFB: -52F
Fairbanks Airport: -51F
UAF West Ridge: -48F

Denali Park VC: -52F (RAWS)
Denali Park Airstrip: -49F
Denali Park Headquarters: -37F

Still Warming Aloft

The high temperature today was just 42 below at the Airport, the lowest daily high temperature since Jan 2, 2000. The afternoon sounding shows slow warming continuing aloft.

A Cool Yule, and then Some

Here's a plot of daily temperatures (high and low temperatures at the top and bottom of the bars) at the Fairbanks Airport since Christmas. Not Hot. So far Saturday, Airport has a high of -42F, low -50F

50 below at Fairbanks

The sunrise view from the Alaska Climate Research Center webcam Saturday morning. Fairbanks Airport has now been down to -50F. The first -50 temperature at the Airport since January 2006. Record low for January 28th is -60F set in 1933.

Serious Cold

Okay, now it's getting seriously cold.

Here's at NOAA-19 infrared, this capture from the UAF Swath Viewer. This B & W rendition has slightly higher contrast than the NWS Alaska Region HQ version:




Updated:
Low temperatures through 10am AST Saturday

Goldstream Creek: -54F
Fairbanks Airport: -49F
Eielson AFB: -47F
UAF West Ridge: -46F
Cleary Summit: -30F

CORRECTED
Elsewhere in Interior Alaska:
Fort Yukon: -63F (cooperative observer)
Husila: -63F
Tanana: -61F (not a record for the date: record low is -68F in 1933)
Bettles: -59F (new record low for Jan 28th)
Chicken: -59F
Bolio Lake: -57F (south of Delta Junction)
Kaltag -56F
Nenana: -53F

Here's the low level temperature plot for last three soundings from Fairbanks. Cold, though the airmass is starting to warm aloft:

More Cold

Scott Bachmeier sent a link to this false color infrared image from early Friday morning (I've reoriented the original image to be longitudinally centered over Alaska):

The purple colors are radiance derived temperatures -50C (-58F) and lower. Over mainland Alaska any temperatures this cold are surface temperatures. These are a bit lower than the surface observations. The difference comes from several different sources, the most of significant of which are satellite calibration and the fact that "surface observations", i.e. METARS, cooperative obs, etc are from thermometers exposed above the surface. Nominal exposure 1.5 to 2 meters above the ground, though some are routinely higher (SNOTEL, RWIS). The presence of the mid-winter snowpack makes the actual thermometer exposure something like 0.5 meters lower in most places north of the Alaska Range.
Skies cleared by mid-morning over Fairbanks. By Noon temperatures have been down to 41 below at the Airport and 42 below at Fort Wainwright and Goldstream Valley.

Now it's Getting Cold

The 320am NOAA-19 Polar Orbiter infrared image shows it is cold over the western Interior. Fairbanks is near one of the last remaining areas of clouds.

As of 7a Friday, lows include:

Tanana 56 below
Hulsia: 56 below
Galena Airport: 53 below
Kaltag: 50 below

More to come…

Really Cold on the North Slope

FAA webcam image from Barrow Tuesday after with thin ice fog and 35 below:

Low temperatures so far Tuesday:

Barrow -45F
Deadhorse Airport: -50F
Umiat RAWS: -59F
Ikpikpuk River: -59F
Nuiqsut: -62F

Near Record Cold January in the Works

Here's an updated plot of daily mean temperatures thus far this winter (through January 23rd). The winds and clouds the past few days have kept temperatures up near normal. Through Monday (the 23rd), the mean January temperature at the Fairbanks Airport is -25.0F. The rest of the month looks to average at least this cold, and probably colder. This will be one of the coldest Januarys of record.

Colder Air Moves in, Temperature Warms 30 Degrees

Here's a plot of the low level temperatures from Friday morning and Sunday morning. The airmass overall has cooled a bit, but the wind has mixed down to the valley floor in many area. The miracle of mixing. Here are the 8am Temperatures from Friday and Sunday:
Fairbanks Airport -33F -4F
Keystone Ridge +2F -10F

The Way Inversions Die

Here's a plot of temperatures and winds from Fort Yukon Saturday. Fort Yukon is an AWOS and reports a full observation every 20 minutes. When the winds broke through the inversion, the temperatures rose 29 degrees inside of 20 minutes.

Mid-Day Image

Nice infrared image from 1pm Thursday from the NOAA-19 Polar Orbiter showing lots of clouds on the North Slope and pushed up into north side of the Brooks Range (note the wavy looking clouds near the crest). Clear skies prevail again over the Interior and West Coast.

Inversion's Growing

Here's the 3pm sounding from Fairbanks. The inversion is growing. Temperatures above 2300' MSL have approached 0F today, and I expect overnight there will be 40 degrees or more between rural valley bottoms and higher elevations. High today at Fairbanks Airport has been -35F; Clearly Summit -3F. Here at Keystone Ridge the temperature has risen from -18F at 3pm to -10pm at 5pm, all without any evident breeze.

How Cold has January Been?

Through the first 16 days of January, the average temperature at the Fairbanks Airport was -25.8F, almost 18 degrees below normal. Temperatures over the next week look to continue to be cold, though nowhere near records for any given day. A reasonable guess would be that by January 24th the average temp for the month will be similar to the current value. What happens thereafter is yet unknown, but temperatures this month will almost certainly finish up being far below normal. So how unusual is this?

Well, in recent years, reasonably unusual. Since 1976, there have been five calender months with an average temperature lower than 20 below: January 2006 (-22.0F), February 1990 (-21.7F), January 1989 (-21.3F), December 1980 (-24.0F) and February 1979 (-25.3F)

So, while the current cold spell is unusual, it is in no sense "unprecedented", even in the context of post-pipeline era Fairbanks, when there is an undeniable urban effect on Fairbanks temperatures, at least in ice fog situations. If anything is unusual, it's the lack of extremely low temperatures, not just in Fairbanks (low so far a paltry -48F) but anywhere in the Interior. Even the 58 below at Chicken is not excessive by their standards. There has only been one or two daily record low temperatures set (at Galena); most places have not even been close. With a comparatively moderate airmass aloft, that situation does not look to change the before the weekend at the earliest.