Sunshine Gaining…but not quite there yet

Here's a plot of the Fairbanks soundings from Sunday and Monday afternoons. The primary item of interest here is that both days featured lots of sunshine and very little wind. Monday especially was almost cloud free. This nicely illustrates that even though the maximum solar elevation is now above 15 degrees, it's still not enough to mix out the boundary layer. Another week to ten days should do it.

Seasonal Snowfall Creeping Up

Here's an update on seasonal snowfall in the Fairbanks area (KERA2=Keystone Ridge, PAFA=Fairbanks International).

Thanks to frequent light snows, snowfall is above normal now in Fairbanks area for February, and is getting back toward normal for the season. Snow depths are generally near or slightly more than two feet in the area.

Colder Early Winters in Fairbanks?

Were only a month away from the vernal equinox now, with possible sunshine increasing at nearly seven minutes a day. Nonetheless, today we'll look back to the dark days of early winter. Fairbanks has had a run of cold early winters, or maybe better, early winters the past few years have featured more cold weather than before that. Is this something new? One way to assess this is simply to examine the number of cold days. Here I've plotted the numbers of days October through December with low temperatures of 20 below or lower. I chose 20 below because temperature that "warm" should not be impacted too much by the urban heat island growth. 

 

What we see here is this past early winter, with 36 days of lows of 20 below or lower before New Years Day, was the third highest total since 1930. The red line represents the 5-year running median, which is now back up to values common in the mid 1990s and during the past negative PDO phase (transitions between phases marked by the black lines). The plot of lowest absolute temperature during early winter does not paint the same picture:

This clearly shows that absolute low temperatures have been increasing. Prior to 1980, temperatures of 50 below or lower did not occur every early winter, but were by no means uncommon. Since 1980…just one year, 1999. This however must, in part, be attributable to increase in urban effect, which is greatly amplified by the formation of ice fog at temperatures colder than -35F. 

Cold Airmass over Fairbanks-Land

It's a chilly airmass over Fairbanks, with afternoon temperatures barely cracking 10 below after morning lows in the 20s and 30s below. Here are the Monday soundings from the Fairbanks Airport. Notice that the temperature only varies by about three degrees Celsius in the lowest kilometer, with not much of a surface inversion. On the up side, it was a bright and sunny day.

Fairbanks Winter Temperature Update

Here's an update on Fairbanks temperatures thus far this winter. Reader Gary asked for a plot showing relative magnitude of the daily departures, and after some fiddling around with Excel I came up with this plot:

The daily mean temperatures are the values at the end of the bars, with above and below normal values colored accordingly. Just eyeballing this you can see that early winter was consistently chilly, while since the last days of December it has been mostly mild except for the few days of deep cold late in January. The actual means are:

Oct 01 to Feb 16 Mean Temp: -1.1F which is 4.0 degrees below the 1981-2010 normals
Dec 01 to Feb 16 Mean Temp: -7.5F which is 2.0 degrees below the 1981-2010 normals
Jan 01 to Feb 16 Mean Temp: -1.1F which is 5.3 degrees above the 1981-2010 normals

Sunshine but not much Heating…Yet

Courtesy of the FAA

The sun rises over Fairbanks-land Thursday to a reasonably sharp inversion. Valley temperatures are just below zero while hillsides are in the 20s above. The inversion held Wednesday, with the high temperature at both Fairbanks Airport and Goldstream Creek of +7F, while Keystone Ridge had a low temperature Wednesday of +13F.

Daytime Inversion Still Holds

The sun is getting higher in the sky every day, but at solar noon the sun is still only 12 degrees above the horizon. This is still not enough to break the inversion without some clouds and/or wind help, as Wednesday afternoon's sounding shows. Temperatures in most places on the valley floor never got out of the single digits, while higher elevations were in the low 20s.

Post-Frontal Sunshine

Courtesy of Alaska Climate Research Center

As sometimes happens, especially with storms moving northwestward from the North Pacific into the Bering Sea, the occluded front has fractured, with the high clouds out-racing and becoming disassociated with the surface front. When this happens, what low level moisture there is stripped out crossing the Alaska Range and a large area of temporarily clear skies develops. That's what happen Saturday afternoon, resulting in a sunny and mild weekend day for Fairbanks, with temperatures in all but the lowest spots jumping up into the upper 20s and lower 30s.

Snow Slowly Catching Up

While the Northeast digs out, here in Fairbanks we plod along, "nickel and diming" our way to near normal snowfall. Here's an updated plot of cumulative snowfall for the season. The big snow in December continues to be the highlight, being (practically) the only significant snow in the two months from early November through early January. Since early January snowfall has been more regular, and the Airport is now up to 90% of normal for the season.

The Sun is Shining, But...

The sun is shining these days at Barrow, but there is not much heating yet. At 4pm Thursday the temperature fell to 34 below as winds shift to the south, which is an overland trajectory at Barrow. This is the lowest temperature so far this winter at Barrow.

Courtesy of the FAA

More Winter Temperatures

Here is a plot of daily mean temperatures so far this winter at the Fairbanks Airport along with the 1981-2010 normal. Recall that the shaded area represents one standard deviation from normal, so actual temperatures that are inside the gray area could be considered as "near normal". 

Cold Still Reigns…For Now

Here's an update of Fairbanks standardized daily temperature anomalies thus far this winter. For those keeping score at home, the average temperature December 1st through February 3rd at the Fairbanks Airport is -9.4F, a substantial 3.4 degrees F below normal. October 1st through February 3rd the mean temperature is -1.4F, a whooping 4.9 degrees F below normal. The 1 to 2 week forecast from the Climate Forecast System has been consistent in keeping most of Alaska quite mild in the mean…so I expect that those impressive seasonal anomalies will decrease during the course of this month. 

Gina Puffin Feeder

Here's a link to a website I just learned about yesterday: the GINA Puffin Feeder site. GINA is a group at UAF that is involved with capturing and distributing Alaska and high latitude imagery from a wide variety of sources.  I've used GINA's Swath Viewer for some years, but yesterday I saw a presentation on the GINA Puffin Feeder website that is distributing imagery from the new VIIRS polar orbiter satellite. It has a variety of interesting images, including true color, landform and a low light visible channel.

Here's the low light visible image taken at 4am Friday. This is unprocessed by me; this is as-is on the website. Look at that detail! The bright swirl on the upper left hand side of the image is aurora, and the lights of Prudhoe Bay, Anchorage and Fairbanks are all clearly visible.

Fairbanks January Summary

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
835 AM AKST FRI FEB 1 2013

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

JANUARY 2013 WAS A ROLLER COASTER OF INTERESTING WEATHER.

THE MONTH OF JANUARY BEGAN UNSEASONABLY WARM...OVER 30 DEGREES
ABOVE NORMAL ON THE 1ST OF THE MONTH. TEMPERATURES FELL BACK TO
NEAR NORMAL GRADUALLY THROUGH THE 10TH OF THE MONTH...UNTIL
UNSEASONABLY WARM SOUTHERLY FLOW PUSHED BACK INTO THE INTERIOR BY
THE 12TH. THE WARM AIR PLATEAUED ON JANUARY 14TH WHEN THE
FAIRBANKS AIRPORT REACHED 37 DEGREES. THE WARM AIR WAS ACCOMPANIED BY A
SWATH OF RAIN AND SNOW WHICH CAUSED WIDESPREAD TRAVEL HEADACHES
THROUGHOUT THE FAIRBANKS AREA. AT THE AIRPORT...0.15 INCHES OF
RAIN FELL...THE GREATEST JANUARY RAINFALL SINCE 1963. IN THE NORTH
POLE AREA...SOME PLACES RECEIVED OVER ONE THIRD OF AN INCH OF
RAIN...AND THROUGHOUT THE AREA MANY ROADS REMAINED ICE COVERED AT
MONTHS END. FOLLOWING THE RAIN...TEMPERATURES COOLED BUT REMAINED
ABOVE NORMAL MOST DAYS UNTIL STAGNANT ARCTIC AIR MOVED IN ON THE
25TH. THE THERMOMETER PLUMMETED TO THE 40S BELOW FOR THE FIRST
TIME OF 2013 ON JANUARY 25TH. THE COLD SPELL OF LATE JANUARY DID
NOT LAST LONG BUT THERE WERE SEVERAL DAYS WHERE AIR QUALITY
EXCEEDED THE EPA HEALTH LIMITS FOR FINE PARTICULATE
POLLUTION...AIDED BY THE USUAL STEEP TEMPERATURE INVERSIONS IN THE
FAIRBANKS BOWL.

OVERALL...THE AVERAGE JANUARY TEMPERATURE WAS 2.7 BELOW. THIS IS
5.2 DEGREES ABOVE NORMAL AND MADE THIS THE MILDEST JANUARY IN
FAIRBANKS SINCE 2002. THE MAXIMUM TEMPERATURE FOR THE MONTH
OCCURRED ON THE 14TH WHEN THE FAIRBANKS AIRPORT REACHED 37
DEGREES. THE MINIMUM TEMPERATURE OF 48 BELOW WAS REACHED ON
JANUARY 27TH...WHICH TIES THE 48 BELOW REACHED ON DECEMBER 17TH
FOR THE LOWEST TEMPERATURE OF THE WINTER SO FAR.

JANUARY ENDS WITH A TOTAL OF 14 DAYS WITH TEMPERATURES OF 40
BELOW OR LOWER AT THE FAIRBANKS AIRPORT. FAIRBANKS HAS NOT REACHED
50 BELOW THIS YEAR...THOUGH SOME TYPICALLY COLDER PLACES
HAVE...INCLUDING LOWS OF 54 BELOW IN TWO RIVERS...52 BELOW AT
NORTH POLE AND 50 BELOW AT GOLDSTREAM CREEK.

PRECIPITATION FOR THE MONTH OF 0.79 INCHES WAS 0.21 INCHES ABOVE
NORMAL FOR THE MONTH OF JANUARY. DESPITE THE ABOVE NORMAL
PRECIPITATION AMOUNTS...SNOWFALL FOR JANUARY OF 9.9 INCHES WAS
ALMOST EXACTLY NORMAL. SNOW DEPTH INCREASED TO 19 INCHES BY THE END
OF JANUARY.

WITH THE CLIMATOLOGICALLY COLDEST PART OF WINTER BEHIND...FEBRUARY
PROMISES TO DELIVER MORE NOTICEABLE DIURNAL TEMPERATURE RANGES AS
THE MONTH PROGRESSES AND THE REGION GAINS OVER 3 HOURS OF POSSIBLE SUNSHINE
BETWEEN THE 1ST TO THE 28TH. AVERAGE TEMPERATURES INCREASE FROM 6
BELOW TO 4 ABOVE BY THE END OF THE MONTH. THOUGH ONLY A 10 DEGREE
AVERAGE INCREASE...THE NORMAL HIGH TEMPERATURES BY THE END OF THE
MONTH IS 17 ABOVE. NORMAL SNOWFALL IN FEBRUARY IS 8.1 INCHES...THOUGH
HISTORICALLY FAIRBANKS HAS OCCASIONALLY RECEIVED DAILY SNOWFALLS
IN EXCESS OF TEN INCHES...MOST RECENTLY IN FEBRUARY 1996 AND
2011.

THE FORECAST FOR FEBRUARY FOR FAIRBANKS FROM THE CLIMATE
PREDICTION CENTER CALLS FOR INCREASED CHANCES OF SIGNIFICANTLY
ABOVE NORMAL TEMPERATURES. 

$$

JM/RT

Elevated Inversion

Here's the Fairbanks sounding from Wednesday afternoon, showing a nice elevated inversion. Temperatures were up into the upper teens to around 20 degrees above 2200' MSL, while zero to 10 above at lower elevations.

Nip in the Air

Courtesy of the FAA

Ice fog was quite dense this morning in Fairbanks  but had almost completely burned off by mid-afternoon, as evidenced by these two views from Ester Dome, the top one from 1138am AST and the bottom one four hours later.  Temperatures are rapidly warming aloft now and winds have picked up at elevation and channeled valleys.

Here are some low temperatures reported the past couple days:

Chicken Co-op: 62 below
Eagle Co-op: 57 below
Two Rivers: 54 below
Eielson AFB: 52 below
North Pole: 52 below
Fort Wainwright: 51 below
Fairbanks Airport: 48 below
Aurora: 45 below
Gilmore Creek: 45 below
UAF West Ridge: 44 below
Keystone Ridge: 29 below

Pacific Decadal Oscillation and Interior Alaska

I often mention the Pacific Decadal Oscillation and Interior Alaska climate, and I've written about it before, but it's so important to understanding climate variability for most of Alaska (except the North Slope), that it's worth updating. 

To start with, below is the classic PDO anomaly diagram from the University of Washington. The color field is the sea surface temperature anomalies and the arrows are the surface wind anomalies. On the left is the positive phase of the PDO and the right is the negative phase. Note that from the North Pacific-wide perspective the phases are misnamed: the positive phase features a huge area of cooler than normal temperatures from Asia to about 155W, and the negative  phase a similarly place warm anomaly. The surface wind anomalies are southerly into mainland Alaska during the positive phase and northerly during the negative phase.  

Courtesy of the U. of Washington

Next is an updated plot of the PDO Index. I constructed this by taking the monthly PDO index page at the UW website and constructed four non-overlapping seasonal means per year (effectively a course low pass filter). The heavy black line is the ten year (40 season) centered running mean. Using a centered mean preserves the timing of the phase transitions.

The phase changes in 1946 and 1976 are pretty clear in the ten year mean, while the early 20th and  21st century transitions are less obvious. At least the 21st century transitions is a little clearer in the even smoother annual averages (note I've used a July to June year in order to capture as a unit the Northern Hemisphere winter):

Since the 2005-06 year, only once (2009-10) has the annual mean PDO been above zero, and even that just barely, and the negative values have been repeatedly lower than any time since the 1976 transition. This is why I place the positive to negative phase PDO transition at 2007.

Deeper Cold

It's colder this Sunday morning across Fairbanks-land, and it's a deep cold. Here's a temperature trace from the early morning sounding. Unlike my usual fashion, this one is for the lowest five kilometers of the atmosphere. This is quite a cold troposphere: the warmest temperature in the entire atmosphere over Fairbanks is just -27.5C. Note too that the inversion right at the at the time of the sounding was not all  sharp: the surface was only about 4C cooler than 400 meters up. Since then the inversion has sharped some as valley temperatures are now well down in the 40s below.

Some low temperatures reported so far (through 9am AST) include:

Fort Wainwright: 51 belo
Eielson AFB: 50 below
Goldstream Creek: 49 below (through 6am) 
Fairbanks Airport: 48 below
UAF West Ridge: 42 below
Keystone Ridge: 28 below
Clearly Summit: 22 below

In the eastern Interior it's, as usual, even colder:

Chicken Co-op: 60 below
Eagle Co-op: 57 below
Fort Yukon: 56 below
Eagle Airport: 55 below
Dawson, YT: 54 below
Circle Hot Springs: 52 below
Northway: 51 below

It's a Cold One

Courtesy of the FAA

It's a cold Saturday in Fairbanks-land. The dawn view from atop Ester Dome shows thin ice fog covering much of the flats. Low temperatures so far this morning include:

Eielson AFB: 49 below
Fort Wainwright: 47 below
Goldstream Creek: 45 below (thru 6am)
Fairbanks Airport: 44 below
UAF West Ridge: 40 below
Keystone Ridge: 25 below
Cleary Summit: 18 below

Extreme Wind Chill in Atigun Pass

Deep cold air is pouring across the central and eastern Brooks Range this morning, creating extremely low wind chills. The NRCS SNOTEL at the top of Atigun Pass (4800' MSL), the highest point on the Dalton Highway, at 7am AST Friday was reporting a temperature of 36 below with sustained winds of 36 mph, gusting to 45 mph. That's a wind chill of 77 below. Farther west, at Anatuvuk Pass at 9am AST it was 24 below with winds 28 gusting 35 mph, a wind chill of 58 below.