Mixed Autumn Signals

In the middle of the night...

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
146 AM AKDT SUN SEP 30 2012

...COOL DAYS RIGHT ON SCHEDULE IN FAIRBANKS BUT STILL NO SNOW...

THE HIGH TEMPERATURE ON SATURDAY AT THE FAIRBANKS INTERNATIONAL
AIRPORT WAS 38 DEGREES...MAKING THIS THE FIRST DAY THIS AUTUMN
WITH A HIGH TEMPERATURE LOWER THAN 40 DEGREES. THIS IS RIGHT ON
SCHEDULE...AS OVER THE PAST 80 YEARS THE AVERAGE DATE IN THE
AUTUMN FOR THE FIRST DAY WITH A HIGH TEMPERATURE BELOW 40 DEGREES
IS SEPTEMBER 28TH.

WHILE THERE HAVE BEEN SNOW FLURRIES IN THE HILLS AROUND 
TOWN...FAIRBANKS IS STILL WAITING FOR THE FIRST SNOW OF THE
SEASON...WHICH IS NOW DECIDEDLY LATE. THE AVERAGE DATE FOR THE
FIRST AUTUMN SNOW IN FAIRBANKS IS SEPTEMBER 21ST.

$$
RT SEP 12

Fire Season Wrap-up

In the little fire season that would not die, the Industrial Park Fire near Delta Junction was up to just under 6000 acres as of Friday morning, while the Dry Creek Fire west of Eielson AFB was last measured measured at 47,154 acres. This brings the total acreage burned in Alaska this year to 266,409 acres, almost exactly 2011's total. The total acreage burned has increased by 28% since the end of July, which seems to me to be unusually high. The culprit has been the warm, dry and at times windy weather in the Tanana valley that has prevailed since August.

Wickersham Dome Weather Station

Big news for Fairbanks area weather buffs: a new automated weather on Wickersham Dome came online yesterday.  It is located near the White Mountains National Recreation area Wickersham Dome Trailhead at Mile 28 Elliott Highway. This is about 20 miles northwest of Fox. The station is at an elevation of 2230' MSL. This is a bit below treeline, and the anemometer is about level with the tops of the tallest trees around it. This is a great place for a weather station and should provide useful temperature and wind information in the winter, plus rainfall data in the warm season. This area gets a lot of convection, and this station fills a big hole in the rain gauge network north of Fairbanks. You can find the data from the Wickersham Dome weather station here and here.

Created by RT with Google Maps

To the right is a map I ginned up showing the locations of real-time reporting weather stations at higher elevations (vaguely) north and west of Fairbanks. I have NOT included any of the CWOP or Weather Underground personal weather stations, as the data availability and quality are highly variable. At the link for this map you can find additional information on the specific sites as well as the weather stations at elevation east of Fairbanks. 

Summer is Gone

Summer is gone, and we know this how? Well, in addition to looking outside and seeing the bare trees, solar heating is now no longer the dominant driver of temperatures in Interior Alaska. Rather, surface cooling (longwave radiation) and horizontal movement of air masses with different thermal characteristics (advection) are starting to overwhelm daytime heating from the sun.

The plot at the right shows hourly temperatures Sunday evening into Tuesday at Keystone Ridge and Goldstream Creek. Focus on Monday evening. With clear skies and no wind, temperatures on the valley floor dropped like a rock after sunset, with the low temperature for the (calendar) day occurring near midnight. Meanwhile, 325 meters up the hill, after briefly  falling a few degrees toward sunset, temperatures not only slowly rose, but the high temperature for the (calendar) day occurred about the same time the valley was reaching the low temperature, not long before midnight. This was possible because, in spite of plenty of sunshine during the day Monday, the high temperature on Keystone Ridge during the afternoon Monday was just seven degrees higher than the morning low temperature. Maximum solar elevation Monday was 24º above the horizon, which is about the same as Chicago on winter solstice.

Warm Equinox

The autumnal equinox occurred at 649am ADT Saturday, but you would not have known it from the  temperatures in the Interior. At Fairbanks Airport, the high of 67F and the low 47F would have been exactly normal for August 14th. Thick cirrostratus covered the Fairbanks area all day, which kept high temperatures down a bit. There were no records set as the 22nd was the last day of the great September 1995 chinook.

Other high temperatures included:

Eielson AFB: 69F
UAF West Ridge: 67F
Aurora: 67F
Fairbanks Mid-town: 67F
Gilmore Creek CRN: 66F
Goldstream Creek: 65F
Keystone Ridge: 61F

Temperatures did nick 70F in the eastern Interior, including 71F at Chicken and 73F at Eagle.

Nenana River Flooding

Hydrograph courtesy of the Alaska-Pacific RFC

The Nenana River at Healy reached the highest stage of record Saturday, causing problems in the Denali National Park east end area.The hydrograph on the left shows a peak stage of 14.9 feet, well above the previous record of 14.4 feet set September 15, 1990. The Fairbanks Daily News-Miner is reporting threats to the Parks Highway north of the Denali National Park entrance as the river erodes the banks. In spots the river is threatening the road, which in a stretch between the Glitter Gulch and Healy is perched on a narrow ledge between the river and the scree slopes. The high stage on the river is the result of copious rains in the headwaters: A SNOTEL (Monahan Flats), which is in the Sustina drainage but only a few miles from the upper Nenana watershed, measured 4.8 inches of rain September 13-21. The recent high freezing levels were likely a secondary factor.

Tina Graham photo from the Fairbanks-Daily News-Miner

Another Chinook

South winds aloft pushed very warm warm air into the central Interior Alaska Friday night and Saturday morning, resulting in dawn temperatures more typical of July than the autumnal equinox. In the Fairbanks area at 8am ADT, temperatures were mostly in the 50s and lower 60s. Here is the 500 mb analysis for 4am ADT Saturday. Note the strong ridge extending from western Montana northward to west of the Mackenzie River, with deep southerly flow over nearly all of mainland Alaska.

Courtesy of Environment Canada

The warming on the Fairbanks sounding between Friday afternoon and Saturday morning was quite dramatic (lowest 1500 meters plotted below). In most places the overnight low temperatures occurred Friday evening and then rose steadily after midnight. Here on Keystone Ridge the high temperature Friday of 55F occurred shortly before midnight. At the Goldstream Creek PWS, the temperature fell to 36F by 1030pm but jumped from 43F to 57F between 5am and 6am as the wind broke through the inversion.

The cirrus is fairly thick this morning but will likely thin in the afternoon, and it is possible, albeit unlikely that the record high for September 22nd of 73F set in 1995 would be broken.

Unseasonable Warmth in the Eastern Interior

Fairbanks-land had a seasonably cool day Thursday with morning fog and a little light rain...pretty typical stuff for around the autumnal equinox. The far eastern Interior though remained in moderate southerly flow aloft around the backside of a strong high aloft over central british columbia..which allowed for some sunshine and unseasonably warm temperatures.

The high of 70 at Northway broke the record for September 20th of 67F set in 1951 (weather observations in Northway date back to 1942). The Climate Reference Network station east of Northway, at the old Seaton Roadhouse site near Alaska Highway Mile 1234 had a high of 75F, while the DOT RWIS at the Alaska-Yukon border had a high of 73F. Tok topped out at 71F, a few degrees shy of the record for the date. Records are a bit higher the next few days, so I would not expect any more records, but it will remain quite mild...and will spread west to Fairbanks for Saturday at least.

Brooks Range Snow

Photo courtesy of the FAA

The clouds broke Thursday afternoon at Chandalar DOT camp on the Dalton Highway (3000' MSL), reveling a pretty snow covered  landscape. Not much snow yet at lower elevations. Even Anaktuvuk Pass still with bare ground.

Arctic Sea Ice Minimum

Courtesy of NSIDC

The National Snow and Ice Data Center has called the 2012 summer Arctic Sea ice minimum as occurring this past Sunday, September 16, with a coverage of 3.41 million square kilometers. This is 18% lower than the 2007 minimum and barely half of the 1979-2000 average seasonal minimum. Note that NSIDC defines ice cover as a 15% coverage or more. It is going to be an interesting autumn, as this is a whole lot of open water way far north.

Wind Recap—Updated

Photo by Rod Combellick via Fairbanks Daily News-Miner

Here are some maximum wind gusts reported Sunday (mostly in the evening) in Fairbanks-land:

Salcha River RAWS: 49 mph
Caribou Peak RAWS: 46 mph
Stuart Creek RAWS: 45 mph (east of Eielson)
Lincoln Creek Ridge PWS: 43 mph  (my neighbor across the hill)
Cleary Summit RWIS: 43 mph
Eielson AFB: 40 mph
Fairbanks Airport: 28 mph

The News-Miner reported some power outages in the area, and the winds brought the Dry Creek fire back to life, as seen in this dramatic photo taken about 930pm ADT Sunday from Chena Ridge.

The SNOTEL on Eagle Summit on the Steese Highway reported a peak wind of 65 mph, and in the Delta Junction area, Fort Greely had a peak wind of 71 mph with a 60 mph gust at the Bolio Lake RAWS.

Big Storm

Analysis from Environment Canada

A rapidly deepening storm in Bristol Bay brought a strong Chinook to the Interior Saturday night and Sunday (4am ADT analysis from Environment Canada on the right). After a week of near or below freezing morning lows, temperatures overnight in many low elevation places in the southern Interior failed to get out of the 50s Saturday night and Sunday morning.  It has been windy in and just to the lee of the mouths of the passes, and most places have had decent breeze. Through 10am ADT Sunday, peak winds reported include:

Fort Greely: 66 mph
Texas Condo: 64 mph (on west side of Donnelly Dome)
Bolio RAWS: 57 mph (near Bolio Lake)
Healy DOT: 48 mph
Otto Lake PWS: 42 mph (south of Healy)

In the Fairbanks area, the highest winds have been in the Eielson AFB area, with a gust to 40 mph at 10am Sunday. 

One more Cool Morning

Low temperatures Thursday morning were below freezing everywhere in the Fairbanks area. The Nenana Hills RWIS, which was the last observation site yet to have a freeze, dipped to 31F. Other lows include (thru 8am):

Goldstream Creek: 18F
Mile 43 Steese Highway: 23F
Fairbanks Airport: 26F
Eielson AFB: 26F
UAF West Ridge: 27F
Keystone Ridge: 31F
Cleary Summit: 34F

Arctic Sea Ice Approaching Summer Minimum

Courtesy of NSIDC

Here's the September 9th plot of Arctic sea ice coverage from the National Snow and Ice Data Center. As to be expected, the coverage is getting close to the seasonal minimum, and is, by far, the lowest coverage of the satellite era.

Frosty

Most of the Fairbanks area had a frost or freeze Saturday morning. At the Fairbanks Airport, the low of 29F made this the earliest "first autumn freeze" since 2005, though this is one day later than the long term median. The photo on the left is from here on Keystone Ridge about 8am Saturday, with frost on the dogwood.






Other lows in the area Saturday morning include:


Goldstream Creek: 22F
Chena Hot Springs: 25F
Eielson AFB: 26F
UAF West Ridge: 28F
Keystone Ridge: 33F
Clearly Summit: 35F

Updated Temperature Anomolies

Here's an updated plot of standardized mean daily temperature anomalies for Fairbanks. Warm anomalies have dominated since mid-August but with some cooler days interspersed, unlike, say much of July, when cool anomalies were unbroken except for late in the month.

Dry as the Airport

Amongst the weather weenies of the Interior, it is common knowledge that the Fairabnks Airport is often the driest place around. Of course it is not always the case, but it sure seem like it sometimes. This is not an ASOS issue; it has been a feature for a long time. I have a co-worker who installed a rain gauge in his back yard in the University West area in the 1980s because he was sure he was getting more rain that the Airport. So, in that vein, here are rainfall totals through the first six days of September, keeping in might it has rained some every day:

Fairbanks Airport: 0.17"
Lemeta (north of downtown) 0.20"
Fairbanks Midtown: 0.26"
North Pole: 0.28"
Gilmore Creek CRN: 0.46"
East Farmers Loop" 0.47"
Goldstream Valley Bottom: 0.54"
Keystone Ridge: 0.77"

Here It Comes

Photo courtesy of the FAA

Here's the 9am Thursday view from Eielson Visitors Center in Denali National Park, elevation 3650' MSL. This is not unusual for Eielson VC: accumulating snow occurs about once every in three Julys, and probably more than half of Augusts. Cool weather is here for a while at least, so it's possible, if unlikely, that this is the start of winter snowpack

Arctic Sea Ice

Courtesy of the University of Illinois

Unless you've been incommunicado the past couple weeks, you have probably heard that Arctic Sea Ice coverage is at the lowest of the satellite era, already lower than the 2007 minimum by quite a bit. Here is the Alaska-centric view from the University of Illinois Cryosphere today webpage. There is a small amount of low concentration ice northwest of Barrow, but it's going fast.

Fairbanks August Summary

NOAK49 PAFG 020014
PNSAFG
AKZ222-021215-

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
414 PM AKDT SAT SEP 1 2012

...AUGUST 2012 WEATHER SUMMARY FOR FAIRBANKS ALASKA...
...NEAR NORMAL TEMPERATURES AND BELOW NORMAL PRECIPITATION...

TEMPERATURES IN AUGUST WERE NEAR NORMAL. THE AVERAGE DAILY HIGH
TEMPERATURE WAS 66.5 DEGREES...WHILE THE AVERAGE LOW TEMPERATURE WAS
46 DEGREES. THE MONTHLY MEAN TEMPERATURE OF 56.3 DEGREES WAS JUST
2 TENTHS OF ONE DEGREE ABOVE NORMAL. THE HIGH TEMPERATURE FOR THE
MONTH WAS 78 DEGREES OBSERVED ON THE 14TH...WHILE THE LOW
TEMPERATURE WAS 37 DEGREES OBSERVED ON THE 22ND. SOME OF THE
TYPICALLY COLD LOW LYING AREAS DROPPED BELOW FREEZING ON THE
MORNING OF THE 22ND...INCLUDING LOWS OF 25 DEGREES AT ESTER
5NE...26 AT GOLDSTREAM CREEK AND 29 AT BOTH EIELSON AFB AND CHENA
HOT SPRINGS. URBAN AREAS AS WELL AS MOST HIGH ELEVATION SITES DID
NOT HAVE A FREEZE DURING AUGUST.

THE MONTH STARTED WITH A DECIDED LACK OF RAIN WITH ONLY 26
HUNDREDTHS OF AN INCH AT THE FAIRBANKS INTERNATIONAL AIRPORT THROUGH
THE 23RD.  ONLY 13 HUNDREDTHS OF AN INCH OF RAIN FELL DURING THE
ENTIRE TANANA VALLEY FAIR FROM THE 3RD THROUGH THE 12TH...AND ONLY
3 HUNDREDTHS OF AN INCH OF RAIN WAS OBSERVED AT NORTH POLE THROUGH
THE 23RD. THE LACK OF SIGNIFICANT RAIN ALLOWED THE DRY CREEK FIRE
11 MILES SOUTHWEST OF EIELSON AFB BASE TO SPRING BACK TO LIFE. THE
FIRE WAS INITIALLY STARTED ON JUNE 23RD BY LIGHTNING BUT REMAINED
INACTIVE DUE TO A COOL JULY. THE FIRE QUICKLY GREW DURING THE 3RD
WEEK OF AUGUST TO JUST OVER 40 THOUSAND ACRES BY AUGUST 24TH...AND
ENDED UP ACCOUNTING FOR NEARLY ONE SIXTH OF THE 249,021 ACRES THAT
BURNED STATEWIDE THIS SUMMER. SMOKE FROM THE FIRE MOVED INTO THE
FAIRBANKS AREA ON THE 18TH AND WAS NOTICEABLE AT TIMES DURING THE
NEXT SEVERAL DAYS...AND ALSO PRODUCED POOR AIR QUALITY AT TIMES.

WET WEATHER FINALLY MADE AN APPEARANCE IN THE FAIRBANKS AREA ON
THE 25TH AND 26TH WITH A TWO DAY TOTAL OF 1.07 INCHES OF RAIN. THE
82 HUNDREDTHS OF AN INCH OF RAIN THAT WAS OBSERVED ON THE 26TH WAS
THE WETTEST DAY IN FAIRBANKS IN OVER 2 YEARS SINCE JULY 21, 2010.
THE MONTH ENDED WITH A TOTAL OF 1.43 INCHES...WHICH WAS 43
HUNDREDTHS OF AN INCH BELOW NORMAL. NO THUNDERSTORMS WERE OBSERVED
AT THE AIRPORT THIS PAST AUGUST.

FOR THE METEOROLOGICAL SUMMER...WHICH IS THE 3-MONTH PERIOD OF JUNE
THROUGH AUGUST...THE AVERAGE TEMPERATURE WAS 59.5 DEGREES WHICH WAS
6 TENTHS OF A DEGREE BELOW NORMAL.  IT WAS THE COOLEST SUMMER SINCE
2008.  A TOTAL OF 4.56 INCHES OF RAIN WAS OBSERVED THIS PAST
SUMMER...WHICH WAS 83 HUNDREDTHS OF AN INCH BELOW NORMAL.  IT WAS
THE 9TH DRIEST SUMMER IN THE PAST 30 YEARS. THERE WERE ONLY 5 DAYS
THIS SUMMER WITH A HIGH TEMPERATURE OF 80 DEGREES OR WARMER...WELL
BELOW THE NORMAL OF 11. MANY RURAL LOW LYING AREAS HAD ONE OR MORE
MORNINGS WITH TEMPERATURES DOWN TO FREEZING EVERY MONTH THIS
SUMMER.

LOOKING AHEAD TO SEPTEMBER...TEMPERATURES COOL SIGNIFICANTLY.  THE
AVERAGE HIGH DROPS FROM 62 DEGREES ON THE FIRST TO 46 DEGREES ON THE
30TH.  SINCE 1905...SEPTEMBER TEMPERATURES HAVE RANGED FROM A HIGH
OF 84 IN 1957 TO A LOW OF 3 IN 1992. AVERAGE RAINFALL IS 1.1 INCHES
WITH AN AVERAGE SNOWFALL OF 1.8 INCHES. SNOW IS RARE DURING THE
FIRST 10 DAYS OF THE MONTH AT LOW ELEVATIONS...BUT THE CHANCE OF
SNOW INCREASES DURING THE SECOND HALF OF THE MONTH. 1992 IS STILL
REMEMBERED BY LONG TIME RESIDENTS WHEN WINTER ARRIVED EARLY WITH
SIGNIFICANT SNOWFALL AROUND MID MONTH...AND A TEN DAY TOTAL OF
OVER 2 FEET OF SNOW. MEASURABLE SNOWFALL HAS BEEN OBSERVED ON 19
OUT OF THE PAST 30 YEARS DURING THE MONTH OF SEPTEMBER...OR 63
PERCENT OF THE TIME. POSSIBLE SUNSHINE DECREASES FROM 14 HOURS AND
33 MINUTES ON THE FIRST TO 11 HOURS AND 21 MINUTES BY THE 30TH.

THE FORECAST FOR SEPTEMBER FROM THE CLIMATE PREDICTION CENTER CALLS
FOR AN INCREASED CHANCE OF ABOVE NORMAL PRECIPITATION.  THERE ARE NO
STRONG CLIMATE SIGNALS THAT INDICATE AN INCREASED CHANCE OF EITHER
ABOVE OR BELOW NORMAL TEMPERATURES.

Fog

After the rain Saturday (which did not amount to much in town), skies cleared and valley fog developed. Here are two views at nearly the same time, about 925am Sunday,  one from UAF West Ridge and one from atop Ester Dome. 

Some rainfall amounts Saturday included:

Fairbanks Airport: 0.01"
Eielsin AFB: 0.01"
Goldstream Creek: 0.10"
Gimore Creek CRN: 0.23"
Keystone Ridge: 0.28"
Caribou Peak RAWS: 0.43"