Rain in Fairbanks

Rain in the Fairbanks area started Friday afternoon, and by early Monday morning most places hard received a good soaking.

Weekend totals include:

Angel Creek RAWS: 2.06 inches
Keystone Ridge: 1.54 inches
Cleary Summit: 1.53 inches
Goldstream Creek: 1.29 inches
Fairbanks Airport: 1.12 inches
Eielson AFB: 1.02 inches

This goes a long ways toward wiping out the August rainfall deficit.

Dry Creek Fire

The Dry Creek fire was started by lightning June 23, but remained an inactive, insignificant fire (less than 500 acres) until mid-August. A stretch of warm weather, and a couple of days of brisk south wind, compounded with hardly any rain since late July, allowed the fire to spring to life and grow rapidly. As of Friday, August 24th, the Alaska Fire Service mapped the fire at just under 42,000 acres (map at right), making this the second largest fire of season in Alaska (the Uvgoon Creek fire in the Noatak valley was over 48,000 acres). Just to the southwest of Eielson AFB, the fire has burned right to banks of the Tanana. Happily, the Tanana here is wide and braided. On the negative side, the fire is perfectly placed to provide bouts of smoke for Fairbanks-land until the snow flies: any wind direction except northeast will push into some part of the area. The fire has received only small amounts of rain over the weekend, and while more will fall through Monday, the rain will be not be anywhere near enough to put out this fire. Warm, dry and  intermittently breezy weather is likely again by mid-week, which will undo what wetting has occurred.

Never in recent memory has a single fire sprung to life in mid-August and grown to account for so much of the total acreage burned in the state: the Dry Creek fire on August 11th accounted for less than 0.1% of the statewide acreage burned: as of Friday, it made up almost 17% of the 250,400 acres burned so far, and this will likely increase as there are no other active fires in the state (and have not been since late July). 

Why So Warm on the North Slope?

Courtesy of NCEP/NCAR Reanalysis

Long time reader Trung asked why it has been so warm on the North Slope this summer. The obvious answer would be that the record low sea ice coverage, but that in fact is probably only a small part of the answer. Ice has actually been more persistent in the Chukchi and far western Beaufort Sea than it has been in a few years, though what's left is rapidly melting now. More important has been the persistent trough aloft centered along about 170W longitude, the same feature responsible for the copious rains over much of western Alaska and the quasi-drought in the Interior. This can be seen in graphic to the right, which shows the mean wind direction (arrows) and speeds (color) at 700 mb (about 3000 meters above the ground) for July 1 through August 20 (speed units are meters per second). South winds blowing across the Brooks Range warm and dry as they descend onto the northern plain in a classic "chinook" effect. Barrow has had 15 days with a daily high temperature above 60F, which ties with 1989 and 1936 for the most such days. It is possible that  a new record could be set in the next ten days or so.

Clear skies and a cool airmass allowed for a more widespread a frost and freeze in the Fairbanks area than has hitherto been the case, though most of urban Fairbanks and hillside areas escaped.

Reported lows include:

Goldstream Creek: 26F
Eileson AFB: 29F
Chena Hot Springs: 29F
Mile 42 Steese Hwy: 32F
UAF West Ridge: 35F
Fort Wainwright: 36F
Fairbanks Airport: 37F
Keystone Ridge: 41F
Clearly Summit RWIS 43F

Here's a nice view from the top of Ester Dome about 6am Wednesday morning, with some thin ground fog on the flats: 

Photo courtesy of the FAA

Record Warmth at Barrow

Barrow has been remarkably mild this month. The high temperature Sunday of 66F was a new record high for August 19th. The low temperature of 48F was not only a record high minimum for the date but the fifth of the past six days to set a record high minimum. At the left is a plot of daily temperature extremes this month, with the 1981-2010 normals for comparison. During the past week low temperatures have been consistently running above the normal high, always a good indicator of extreme warmth.

Smoky in Fairbanks

The dry summer in Fairbanks is coming back to haunt us.  The Dry Creek fire, centered 11 miles southwest of Eielson AFB,  reportedly started by lightning June 23rd but dormant in July, sprang back to life a few days ago with the warm dry weather of late. The Alaska Fire Service now estimates 3000 acres burned, an increase of 2500 acres since Wednesday. The plume was visible from UAF for a while late Saturday morning, but soon became hidden by smoke as the fire was fanned by a southeast breeze, so directing the smoke directly toward Fairbanks. For a while Saturday afternoon visibility was under 15 miles from UAF West Ridge, as the buttes south of the river were obscured. Interestingly, the Saturday afternoon sounding from Fairabnks should a well defined inversion aloft, which served to trap the smoke in the lowest 2300 meters of the atmosphere.

Through Friday Fairbanks airport had received only 0.26 inches of rain thus far in August, and the Woodsmoke cooperative station, near North Pole had just 0.06 inches for the month.

Update: Here is a photo of the fire Sunday afternoon looking southeast from UAF West Ridge:

Denali Sunrise

Photo Courtesy of the FAA

Beautiful sunrise on Denali this morning as seen from Eielson Visitors Center. Low temp at the VC this AM was 41F.

The Deepening Night

Daily solar heating is decreasing rapidly now, and the effects of less daytime heating and longer nights are showing: it's almost getting (briefly) dark now. This is being accentuated by high pressure aloft, which is keeping skies mostly clear over the Interior: below is the 500mb analysis for 4am ADT Friday from Environment Canada, showing the elongated high centered about at 63N.

Updated Friday morning low temperatures in Fairbanks-land show a substantial nocturnal inversion and include:
Angel Creek RAWS: 28F
Goldstream Creek: 29F
Woodsmoke PWS: 32F (near North Pole)
UAF West Ridge: 39F
Eielson AFB: 39F
Fairbanks Airport: 42F
Keystone Ridge: 47F
Clearly Summit: 49F
Nenana Hills RWIS: 51F

Snow in Atigun Pass

Courtesy of the FAA

Alaska DOT reported four inches of new snow on the Dalton Highway on top of Atigun Pass (4700' MSL). The SNOTEL at the top of the pass reported a couple inches of snow on the snow pillow for a few hours Tuesday morning.. The 9am Tuesday webcam photo from Chandalar DOT looking northeast shows snow far down the shoulders of the mountains.

Deep Arctic Storm

1200 UTC Aug 06 2012 Analysis Courtesy of Environment Canada

A remarkably deep storm for the high Arctic brushed Alaska's North Slope Sunday and early Monday. To the right is the Monday 4am ADT (Aug 06 1200 UTC) analysis from Environment Canada, with a minimum sea level pressure of 964mb. Part of the reason for the extraordinarily low pressure was that very warm, moist air from Siberia, yes Siberia, was feed into the system as it developed over the East Siberian Sea on Saturday. The storm was too far north to do much for sea ice transport close to Alaska.

No Ice in Barrow

Winds have gone southwest at Barrow but as of Saturday morning ice has not made back to shore. The 4am ADT analysis from Environment Canada shows that the strongest west winds are far north of Barrow.

Courtesy Environment Canada

Courtesy UAF Ice Group

Barrow Ice Free

Courtesy of the UAF Sea Ice Group

Here's the UAF Sea Ice Group webcam photo from Barrow Thursday afternoon. In this limited view, I can't see any sea ice. A storm will be passing by to the north of Barrow Friday, which will bring winds around to the west, It will be interesting to see if ice reappears.

July Summary

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
1231 PM AKDT WED AUG 1 2012

...MONTHLY WEATHER SUMMARY FOR FAIRBANKS ALASKA...
...JULY WAS COOL WITH VARIABLE RAINFALL...

TEMPERATURES IN JULY WERE CONSISTENTLY COOL...WITH 20 DAYS HAVING
AN AVERAGE DAILY TEMPERATURE BELOW NORMAL. THE AVERAGE DAILY
HIGH TEMPERATURE WAS 69.7 DEGREES...A FULL THREE DEGREES BELOW NORMAL
AND MAKING THIS ONLY THE SIXTH JULY IN THE PAST 30 YEARS TO HAVE
AN AVERAGE HIGH IN JULY BELOW 70 DEGREES. THE AVERAGE LOW OF 52
DEGREES WAS ALMOST EXACTLY NORMAL. THE MONTHLY MEAN TEMPERATURE OF
60.8 WAS 1.7 DEGREES BELOW NORMAL AND MADE THIS THE COOLEST JULY
SINCE 2008. THE HIGHEST TEMPERATURE AT THE AIRPORT FOR THE MONTH
WAS 81 DEGREES ON THE 26TH...THE ONLY DAY IN JULY TO REACH INTO
THE 80S. THE LOW AT THE AIRPORT WAS 43 DEGREES ON THE 31ST. SOME
OF THE TYPICALLY COLD LOW LYING AREAS SAW ONE OR MORE MORNINGS
WITH TEMPERATURES DOWN TO FREEZING...INCLUDING LOWS OF 30 DEGREES
AT GOLDSTREAM CREEK AND 32 DEGREES AT WOODSMOKE...NEAR NORTH
POLE... ON THE MORNING OF THE 9TH.

RAINFALL WAS...AS IS TYPICAL IN THE SUMMER...QUITE VARIABLE AROUND
THE AREA. THE FAIRBANKS AIRPORT RECORDED 1.72 INCHES OF RAIN...ONLY
ABOUT 80 PERCENT OF NORMAL. MOST LOCATIONS HAD SOMEWHAT MORE RAIN THAN
THE AIRPORT AND SOME PLACES EAST OF FAIRBANKS WERE ACTUALLY SOMEWHAT
WETTER THAN NORMAL. AVAILABLE JULY RAINFALL TOTALS INCLUDE...

FAIRBANKS MIDTOWN..........1.87 INCHES (77 PERCENT OF NORMAL)
GOLDSTREAM CREEK...........2.24 INCHES
AURORA.....................2.28 INCHES (90 PERCENT OF NORMAL)
NORTH POLE.................2.30 INCHES (99 PERCENT OF NORMAL)
KEYSTONE RIDGE.............2.50 INCHES (75 PERCENT OF NORMAL)
EAST FARMERS LOOP..........2.55 INCHES
WOODSMOKE..................2.71 INCHES (108 PERCENT OF NORMAL)
EIELSON AFB................2.72 INCHES (115 PERCENT OF NORMAL)

THUNDERSTORMS WERE UNCOMMONLY RARE THIS MONTH...WITH THUNDER HEARD ON
ONLY ONE DAY AT THE AIRPORT. THE LIGHTNING DETECTION SYSTEM
OPERATED BY THE ALASKA FIRE SERVICE RECORDED FEWER STRIKES THIS
MONTH IN INTERIOR AND NORTHERN ALASKA THAN ANY JULY SINCE 2003.

THE COOL WEATHER AND LACK OF LIGHTNING BROUGHT THE 2012 FIRE SEASON TO
A NEAR STANDSTILL BY THE END OF THE MONTH. JUST OVER 207200 ACRES HAVE
BURNED IN ALASKA THUS FAR THIS SUMMER. THIS IS WELL BELOW NORMAL AND
THIS SUMMER IS VERY LIKELY TO FINISH UP WITH THE LOWEST ACREAGE BURNED
SINCE 2008.

LOOKING AHEAD TO AUGUST...TEMPERATURES START TO COOL SIGNIFICANTLY AS
NIGHTTIME DARKNESS RETURNS TO FAIRBANKS SKIES. THE AVERAGE HIGH
TEMPERATURE AT THE FAIRBANKS AIRPORT FALLS FROM 70 DEGREES ON THE FIRST
TO 62 DEGREES ON THE 31ST. AVERAGE DAILY LOW TEMPERATURES DROP FROM
50 DEGREES THE FIRST SEVERAL DAYS OF THE MONTH TO 41 DEGREES AT MONTHS
END. FROST AND FREEZES ARE INCREASINGLY POSSIBLE AS THE MONTH WEARS ON...
BUT THE FIRST FREEZE OFTEN DOES OCCUR IN MUCH OF URBAN FAIRBANKS AND IN
THE HILLS UNTIL SEPTEMBER. SINCE 1905...AUGUST TEMPERATURES HAVE RANGED
FROM A HIGH OF 93 DEGREES IN 1994 TO A LOW OF 21 DEGREES IN 1921.
AVERAGE RAINFALL AT THE AIRPORT IS 1.88 INCHES...SLIGHTLY LESS THAN THE
AVERAGE IN JULY. SNOW IS VERY RARE AT VALLEY LEVEL IN AUGUST BUT HAS
OCCURRED A FEW TIMES. THREE INCHES OF SNOW FELL AUGUST 29 1922...THE
ONLY OCCURRENCE OF MEASURABLE SNOW IN AUGUST IN FAIRBANKS IN MORE THAN
A CENTURY OF RECORDS. POSSIBLE SUNSHINE DECREASES FROM JUST OVER
18 HOURS ON THE FIRST TO 14 HOURS AND 40 MINUTES BY THE 31ST. THE
FIRST NORTHERN LIGHTS OF THE SEASON ARE OFTEN SEEN DURING THE LAST
TEN DAYS OF AUGUST.

THE FORECAST FOR AUGUST FROM THE CLIMATE PREDICTION CENTER CALLS FOR
SLIGHTLY INCREASED CHANCES OF SIGNIFICANTLY BELOW NORMAL TEMPERATURES
AND EQUAL CHANCES OF SIGNIFICANTLY BELOW...NEAR OR SIGNIFICANTLY ABOVE
NORMAL PRECIPITATION.