Barrow will have Warmest October of Record

Barrow looking north, Sunday 1030am. Courtesy of UAF Sea Ice Group

The mean temperature for the first 27 days of October at Barrow has been 28.0F. The warmest October was 2006 with an average temperature of 25.5F. This means Barrow would have to have an average temperature of 8.6F the last four days of the month NOT to set a new record for the entire month. Since winds remain west to northwest, there is no chance at all of that happening and it is a certainty that Barrow will have the warmest October of record. 

October Temperature Departures

Dawn Saturday at Lake Minchumina, courtesy of the FAA

For the first 26 days of October, here are the average temperature departures from normal (1981-2010 normals) for some NWS locations:

Juneau: -2.9F
Anchorage: -1.2F
Fairbanks: -2.1F
McGrath: +1.1F
Bethel: +1.2F
Nome: +2.1F
Kotzebue: +3.7F
Barrow: +9.1F

Find the outlier.

Freeze-Up Nearly Complete

Courtesy of Pro Music

Here's a view from Friday afternoon from the Pro Music webcam looking south across the Chena River in downtown Fairbanks. As you can see, freeze-up is nearly complete.

Wimpy No More

If Tuesday morning's inversion was lackluster by Interior Alaska standards, Wednesday morning's sounding looks a lot more like what we expect in winter. Temperatures above the valley floor have been rising since early Tuesday evening, and overnight the winds picked up. Nothing extreme, but enough to "mix it up". With clear skies under the big high aloft, the valley floor continues to cool, and the resulting inversion becomes self-reinforcing, isolating the valley surface from winds generated by the moderate pressure gradient. The result of all this are temperatures in the teens below in the usual cool areas on the valley floor (-15F at Goldstream Creek at 8am) to the teens above well up in the hills (+16F at Keystone Ridge at 8am). Fairbanks Airport has been down to 9 below thus far, the lowest of the season to date.

A Little Inversion

The surface based temperature inversion was fairly underwhelming at 3am Tuesday, as shown in the plot on the left: only about 9ºC in 1000 meters. After balloon launch time surface temperatures cooled some more before fairly widespread fog developed. Fairbanks Airport got to 6 below, Woodsmoke PWS 14 below and Goldstream Creek 16 below. Here on Keystone Ridge as of 9 am it's been down to 1 above; as I write this I'm looking at lovely dawn colors in the eastern sky, with the tops of the fog in the valley well below.

First Sub-Zero in Fairbanks

Arctic Village Monday afternoon. Courtesy of the FAA

Fairbanks Airport reported a low of 5 below Monday morning, the first sub-zero temperature of the season, and about a week earlier than average. For comparison, the record low for Oct 22nd is 16 below set in 1956.

Chicken reported 21 below and Arctic Village 18 below for lows Monday morning. Just like winter. Only warmer…

Sub-Zero Around Fairbanks

Courtesy of UAF's Alaska Climate Research Center

Friday evening a few of the normally cold spots nicked just below zero, but this sunny Sunday morning subzero temperatures are more widespread. Through 10am lows include:

Woodsmoke PWS -7F  (near North Pole)
Chena Hot Springs: -6F
Goldstream Creek: -5F
Eielson AFB: -5F
Fort Wainwright: +2F
Fairbanks Airport: +3
UAF West Ridge: +4F

Keystone Ridge: +10F

Putting Down the Winter Snowpack

The Fairbanks area received three to five inches of snow over the course of several days early this week, with the result that everywhere in the area now has a solid snow cover. In spite of the mild weather early in the month, this is right on schedule: the long term median date for establishment of the permanent winter snow cover is October 18th. It is possible, but high unlikely, that the current snow cover could be reduced to a trace. Since 1929, twice has there been two inches of snow on the ground (the current snow depth at the Airport) on October 20th, only to have it melt back to a trace later in the month. Snow cover is defined here to be a snow depth on one inch or more at the standard time of day for snow depth reporting (traces do not count) and each day thereafter also has one inch or more on the ground through March 31st.

A couple of things stand out on the chart. First, in the past twenty years there has been much less variability in when the winter snow pack was established compared to previous decades (only one year more than 10 days from the median). Also note that it's a lot more common to have very late establishment of snow pack than very early. Only two autumns has the snow pack been established more than 15 days early (1956 and 1992), but seven times has the snow cover been more than 15 days late (though none since 1982). This includes the remarkable autumn of 1934, when the thin snow cover of November was obliterated by the super Chinook of December 3-8, 1934 and then there was no measurable precipitation until after the day after Christmas, resulting in the only "brown Christmas" in Fairbanks weather history.

Fairbanks Temperature Update

After a mild start, October temperatures having been running below normal mid-month. Here's the 2012 plot of daily standardized temperature anomalies for Fairbanks through Thursday, October 18th.

Freeze-Up Underway

Here's a webcam photo taken Saturday morning from Pro Music looking south across the Chena River in downtown Fairbanks. As you can see, there is some ice showing up now. With sub-freezing weather now in place, the rivers will freeze quickly over the next few days.

More on October and Winter Temperatures in Fairbanks

Continuing on the thread that Richard of Georgia asked of "Do October temperatures have predictive value value for the upcoming winter?"

A few days I presented a scatter plot of mean October temperatures vs. mean December through February temperatures, and the results were not encouraging.

Here I abstract away from the actual mean temperatures and give you the rank correlations for the 82 winters since 1930-31 (1 being the coldest and 82 being the warmest).  So, each point represents a pairing of the rank in the 82 winters of October mean temperature and the corresponding rank of the following mid-winter. As you can see, the correlation is pretty weak. However, just looking at the ten coldest Octobers (far left on the x-axis), what I see is that the following mid-winter has not been among warmest, while with the warmest Octobers (far right on the x-axis), there are no really cold mid-winters. So, what I get out of this analysis is that if there is an unusually cold or warm (top ten) October, then past performance suggests that the following mid-winter will not be among the extremes of the opposite sign, i.e. a very cold October is most unlikely to be followed by very warm mid-winter, (but could easily be above normal) and vice versa. Outside of the extremes, I find no useful signal at all.

I did look at the 1946-1976 negative PDO phase and the 1976-2007 positive PDO phase. During the negative PDO, the ranked correlation was slightly higher (0.19) than the full 82 years, while during the positive PDO phase the ranked correlation was an abysmal 0.08.

First Sub-Zero Temperatures of the Season

It helps to have snow on the ground to get temperatures down below zero, but you don't need it. A number of places got that cold this morning, and most of those places have no snow cover at all. These are the first subzero temperatures of the season in Alaska. Here's an FAA webcam photo from the Eagle Airport Thursday afternoon, where the low temperature was 1 below.

Courtesy of the FAA

Other lows Thursday morning included:

Chicken: -5F (snow early last week all melted)
Chalkyitsik RAWS: -4F (east of Fort Yukon)
Tok CWOP: 0F
Kandik River Coop: +5F

Record Warm Start to October at Barrow

For the first time in nearly a century of instrumented weather observations at Barrow, the average temperature for the first ten days of October was above freezing. The average temperature of 32.1F is 0.6 degrees warmer than the previous record of 31.5F in 1977. During the first ten days of the month Barrow set two record highs (41F on the 5th and 38F on the 6th) and was within a degree of the record high on the 7th with a high  of 37F. The 1981-2010 normal temperature for this period is 23.5F.

Okay, whoop-dee-do. Half a degree. Breaking a record set 35 years ago. However, when taken in context, the significance becomes unequivocal. Here is a plot of the mean temperature for the first ten days of October since 1920 (blue) and the 10-year running mean (black). Notice that there was a bunch of warm periods in the 1930s and 40s, but since 2002 there have been ZERO cold starts to October. It wasn't like this in the 30s. The lack of near shore sea ice does not guarantee there will be record warm temperatures. But it does mean that even over as short of a period as ten days, there are many more ways to be warm (compared to long term societal and environmental expectations) than otherwise.

October and the Upcoming Winter

Richard from Georgia asked about the correlation of temperatures in October to the following winter. As a first crack at answering this, to the left is a plot of the October mean temperature vs. the mean temperature the following mid-winter, December through February. I've divided up the scatter plot in four quadrants based on the mean temperatures for the 81 years of data used here. As you can see, there is not much correlation (R=0.13). Some cold Octobers are followed by very mild winters, and vice versa. For example, Oct 2000 had an average temperature of 22.3F, about 3 degrees below the long term average, but was followed by the warmest mid-winter in the past 82 years. In contrast, last October was very mild (mean temperature 28.9F), but was followed by a  mid-winter with an average temperature of -11.0F, the coldest in years. 

However, this is not the whole story. We know that the warm phase of the Pacific Decadal Oscillation (1976-2007) correlated with much warmer winters in Interior Alaska than previous decades, but October (and the autumn in general) did not warm very much at all during the same time period.  I'll take at look at this complication in another post.

No Snow in Golden Heart City

Fairbanks is still waiting for the first measurable snow of the autumn, and it's getting quite late in the season to still be waiting for that important event. At the right is a histogram of dates of first measurable (0.1" or more) of the autumn since 1930. Only in 13 of the past 82 years has the first measurable snow been October 10th or later. Cooler weather looks to be in place now, but after Monday's soaker there is no precipitation at all in the forecast for the next several days. In recent years the latest dates for first measurable snow are last year, October 13th, and 1979, October19th.

Rain and Snow

Central, Alaska. Courtesy of the FAA

Updated:
Fairbanks was soaked Sunday night and Monday with about three quarters of an inch of rain. Although I can't be sure because of mixed rain rain and snow events, it looks like the 0.76 inches of rain from late Sunday to Monday afternoon is the third greatest rain event of record in Fairbanks for the month of October. The snow level remained pretty high through the event. Here at Keystone Ridge there was some wet snow at times but it only briefly accumulated before melting. Above 2000 feet MSL there was more: coming home from work Monday afternoon I observed about 3 inches of wet snow at 2400 feet on Murphy Dome Road. The Eagle Summit SNOTEL, at 3600 feet elevation, evidently had about five inches of snow.

Record Warmth at Barrow

Courtesy of UAF Sea Ice Group

The temperature at Barrow on Friday reached 41F at Barrow, breaking the previous record of 39F set in 1925, and just two degrees from the record high for the month of October. At the left is the Sea Ice cam photo from 930am Saturday. Notice anything odd in this picture? If you said "no snow on the ground", you'd be right. Barrow gone this late in the autumn without any snow on the ground just five times in the past 95 years. Four of those years have been since 1998.

Brooks Range Autumn

Here's a webcam shot from Friday morning at Ivotuk, a research site southwest in the Brooks Range of Umiat at about 2000 feet elevation. Temperatures overnight remained a bit above freezing, but cooler air will return over the weekend and this snow cover is likely to be there until late May or early June.

Warm October Day

Temperatures rose into the 50s and lower 60s in southern Interior Alaska on Thursday. The high at Fairbanks Airport of 61F was just a degree shy of the October 4th record of 62F set in 1923. Other highs included 61F at Fort Greely, 59F at Fort Wainwright and Nenana, 58F at UAF West Ridge and 54F at Keystone Ridge. The unseasonably warm weather is the result of deep southerly flow aloft. This geostationary image from 630pm ADT Thursday tells the story:

The deep low in the central Bering Sea is the extra-tropical rebirth of ex-Typhoon Jelawat. The occlusion is stretched northeast to southwest across mainland Alaska, and south of Kodiak you can see the clouds arcing around a big high aloft centered over the southeast Gulf of Alaska. While temperatures will cool off some, for the most part it looks to remain warmer than normal through the weekend.

Heavy Snow in the FortyMile County

An innocuous looking cloud mass associated with weak closed low aloft brought heavy snow to a small area in far eastern Interior Sunday into early Monday. The NOAA-19 polar orbiter image from  543am ADT Monday shows a hint of the closed low center just southeast of Chicken.

The cooperative observer at Chicken reported 8.0 inches of snow (0.60 inches liquid) Monday morning. Chicken is at about 1800' MSL, and no doubt higher elevations along the Taylor Highway received more. Eagle reported exactly the same amount of liquid as Chicken, but because Eagle is almost 1000' lower elevation, the precipitation fell as rain or mixed rain and snow, with no accumulation in Eagle proper. There was just a dusting at Tok and Northway.

September Summary For Fairbanks

What I did last night...

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
611 AM AKDT MON OCT 1 2012

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

SEPTEMBER WEATHER IN FAIRBANKS WAS LARGELY UNEVENTFUL...WITH
ALTERNATING PERIODS OF WARM AND COOL WEATHER AND WELL BELOW NORMAL
RAINFALL. THE STORM AT MID MONTH THAT BROUGHT DAMAGING WINDS TO
PORTIONS OF THE UPPER TANANA VALLEY WAS NOT NEARLY SO STRONG IN
THE FAIRBANKS AREA.

OVERALL...THE AVERAGE HIGH TEMPERATURE AT THE FAIRBANKS AIRPORT WAS
55 DEGREES AND THE AVERAGE LOW 36 DEGREES. THE AVERAGE TEMPERATURE 
FOR SEPTEMBER OF 45.5 DEGREES MADE THIS THE COOLEST SEPTEMBER
SINCE 2004...BUT WAS STILL 0.6 DEGREES WARMER THAN NORMAL. THE
HIGHEST TEMPERATURE LAST MONTH WAS 67 DEGREES ON THE 22ND AND THE
LOW OF 26 DEGREES OCCURRED ON THE 13TH AND 30TH. AT THE AIRPORT 
THE FIRST FREEZE OF THE AUTUMN OCCURRED ON THE 8TH...WHICH IS
ALMOST EXACTLY THE LONG TERM AVERAGE DATE OF THE FIRST FREEZING
TEMPERATURE.

FOR THE THIRD MONTH IN A ROW...PRECIPITATION WAS WELL BELOW
NORMAL. JUST 0.55 INCHES OF RAIN FELL AT THE AIRPORT...WHICH IS
ONLY HALF OF NORMAL. ABOUT HALF OF THAT SCANT TOTAL FELL ON THE
20TH AND 21ST. FOR JULY THROUGH SEPTEMBER THE TOTAL RAINFALL WAS
72 PERCENT OF NORMAL. THIS PERSISTENT DRY WEATHER ALLOWED THE DRY
CREEK FIRE...ON THE FLATS WEST OF EIELSON AFB...TO CONTINUE TO
BURN...ESPECIALLY WHEN FANNED BY GUSTY WINDS. AN UNUSUAL LATE
SEASON THUNDERSTORM RUMBLED ACROSS THE EAST SIDE OF FAIRBANKS
AND IN THE NORTH POLE AREA DURING THE AFTERNOON OF THE 9TH...WHEN
SOME SPOTS HAD THE GROUND WHITENED IN HAIL. 

THE ONLY SNOW OF THE MONTH IN TOWN FELL ON MORNING OF THE 30TH.
JUST A TRACE FELL AT THE AIRPORT BUT SOME NEIGHBORHOODS RECEIVED
A SHORT LIVED DUSTING. EVEN IN THE HILLS THERE WAS NO SIGNIFICANT
ACCUMULATION. 

LOOKING AHEAD TO OCTOBER,,,THE PERMANENT WINTER SNOW PACK IS
ALMOST ALWAYS ESTABLISHED SOMETIME IN OCTOBER. AS A RESULT THE
AVERAGE DAILY TEMPERATURE FALLS 25 DEGREES DURING THE MONTH...FROM
AN AVERAGE OF 36 DEGREES ON THE FIRST TO 11 ABOVE ON HALLOWEEN.
OVER THE PAST 107 YEARS...OCTOBER TEMPERATURES HAVE RANGED FROM 72
DEGREES IN 2003 TO 28 BELOW IN 1935. TOTAL PRECIPITATION AVERAGES
0.83 INCHES. MUCH OF THIS TYPICALLY FALLS AS SNOW...AND SIGNIFICANT
RAINFALL IS RARE AFTER MID-MONTH. NORMAL SNOWFALL IS ABOUT 11
INCHES. THE LAST TIME FAIRBANKS DID NOT HAVE A WHITE HALLOWEEN WAS
IN 1962. RAPIDLY DECREASING POSSIBLE SUNSHINE CONTRIBUTES TO THE
TRANSITION TO WINTER...FALLING FROM 11 HOURS AND 14 MINUTES ON THE
1ST TO 7 HOURS AND 53 MINUTES ON THE 31ST.

THE OUTLOOK FOR FAIRBANKS FOR OCTOBER FROM THE CLIMATE PREDICTION
CENTER CALLS FOR INCREASED CHANCES OF SIGNIFICANTLY ABOVE NORMAL
TEMPERATURES AND PRECIPITATION.