Holy Cold Front, Batman

It's not every day a real live cold front comes through. Here are the hourly temperatures from Keystone Ridge. The big plunge was accompanied by a quick burst of snow; 1.8 inches between 2pm and 4pm.

Fairbanks above 0F

The temperature made it above 0F this (Thursday) morning at the Fairbanks Airport for the first time since Dec 4th. The 25 straight days in a row remaining at or below zero is not a record, but is the longest such streak since 1977, when it didn't get above zero between November 23rd and December 19th, 27 straight days.

Super Cold Siberia

Playing catch-up here: Oymyakon, in eastern Siberia and a perennial cold spot, had a low temperature on Christmas Eve of -75F. The high temperature the 23rd was -69F. That's cold. Even by their lofty standards. This might be exceeded early next week if it clears out.

Nome Sunshine

End of the year sunshine on Anvil Mountain, looking north from the Nome Airport, 115pm Wednesday. Photo from the FAA.

Pattern Change on the Way

The long chill is coming to an end. This mornings GFS (1200 UTC run) shows 2011 starting off with a significant Chinook. More to come.

Christmas Heat Wave

As of noon Fairbanks Airport is up to -1F...the warmest temperature since Dec 4th. Closer to the Alaska Range, where skies have remained clear, it's still in the 20s below at valley level.

Morning Inversion

This morning's inversion is pretty steep, even by Fairbanks standards: 13.6C (25F) degrees in the lowest 100 meters. The Airport dipped to -40F before the clouds arrived, the fourth -40 day of the month.

Balmy Hills

204p, Thursday, almost sunset photo from Delta Junction, from the FAA.

Meanwhile, back at the Ranch, at 7pm Thursday:
North Pole -44F
Eielson: -42F
Fairbanks: -37F
Cleary Summit: -10F
Keystone Ridge: -8F

Shallow Sloped Inversion

A shallow slope to the inversion Wednesday, thanks to some clouds and flurries. Here on the ridge, this might wind up as the first day of the winter with a high temperature in the double digits below.

Persistent Inversion

The persistent strong inversion, rather than any extremely cold airmass. The inversion has not been broken by any significant storms, with only 2.5 inches of snow thus far this month at the Airport. The plot shows the lows at the Fairbanks Airport and Keystone Ridge. Notice that here on the ridge it is yet to hit 20 below.

High level heat

One of the characteristics of a polar airmass in winter is the fact that the warmest temperatures in the troposphere often occur far above the ground. This morning's RAOB from Fairbanks has a nice illustration of this. The warmest temperature in the sounding is 9200 feet (2800 meters) above the ground.

The big six-oh

Updated: Noon at Fort Yukon: sunny and 58 below.

The AWOS at the Fort Yukon airport reports -60F this morning, after a high temperature of -56F Friday. That's just like winter. Only colder.

Black Stratus again

"Black stratus" is the in-house jargon term for low-topped status or stratocumulus that appear darker than surrounding ground on conventional infrared satellite imagery over Interior Alaska in winter, as the cloud tops are warmer than most of the ground. This mornings' NOAA-19 POES image shows a slug of clouds that moved into the eastern Interior from the Yukon Thursday night. Underneath the clouds, valleys are mostly 15 to 30F below this morning. Elsehwere, mostly 30 to 45F below, except on the Yukon Flats, which appear in this image as obviously "whiter", i.e. colder than most other clear valleys. Fort Yukon AWOS reports 56 below this morning, the lowest of the season. The Beaver Creek and Chalkytsyik RAWS temperatures have stopped reporting, but they are probably around -60F.

First 40

Fairbanks Airport made 41 below Wednesday evening, the first 40 below of the season. Most of the North Pole area was in the mid 40s below, though KJNP reported 52 below, 5 degrees colder than Woodsmoke, which makes you say hum...

Subtle Changes

The afternoon RAOB at Fairbanks shows significant cooling between about 100 and 300 meters, with no change at the surface and a little warming above 300 meters above the valley floor. Although narrow, the 200 meters of cooling is where most of the hill-dwellers live.

50 below sunshine

The noon sun peaks above the ice fog at Beaver, on the Yukon River. Temperature around 50 below.

All Valleys Not Equal

It's another inversion plot, you say. Yet it is not so.

Two valley station, Fairbanks Airport, and the Angel Creek RAWS, near 53 Mile Chena Hot Springs Road. Both valley bottom locations. The difference: terrain orientation. Fairbanks Airport is ringed by hills on three sides. Angel Creek is in a narrow valley that tends to funnel any northeast pressure gradient. The result is a persistent breeze right to the valley floor that largely busts the inversion. Go past Angel Creek and the road makes a braod curve into Chena Hot Springs and, presto, the wind (usually) drops off and the temperature dips.

Cold Morning

Updated Lows
Coldest morning of the season thus far in most valleys around Fairbanks-land. The Airport has been down to 39 below, Fort Wainwright and Eielson AFB 42 below, and some of the North Pole area places in the mid-40s below. Strong inversion (of course), with elevations above 1000' MSL 10 to 15 below. Overnight low at Keystone Ridge -9F with enough of a breeze to drive the wind mill.

Arctic Village

44 below and a fiery sky at Arctic Village Sunday afternoon. Fort Yukon AWOS was down to 53 below, the lowest reported temperature in the state.

First 50

Fort Yukon has the first 50 below of the season in Alaska (I think). The AWOS had 53 below, the RAWS 52 below, the SnoTel 55 below. Take your pick, all three platforms are on the grounds of the Fort Yukon Airport. The Fort Yukon coop observer, who does not live at the Airport, had 50 below.

The miracle of clouds

Clouds moved in after dark Thursday afternoon, and there's been some light snow. The effect on temperatures has been dramatic. Or not. As the plots at the right shows, there has been warming in the lowest 100 meters above the valley floor, cooling 100-400 AGL, and not much change above that. The temperature traces tell the same tale: dramatic warming on the valley floor, and with slight cooling in the hills. It's classic Interior Alaska in the winter.

Continued cooling but stratus looming

Here's Thursday afternoon's RAOB along with the Wednesday afternoon launch. The cooling is modest below 125 meters above the valley floor, but much more greater above.

Meanwhile, the 122pm AST NOAA-19 Polar Orbiter image shows the Fairbanks bowl flanked by "warm" stratus to the south and east. The clouds will not impact temperatures too much in the hills, but are worth 20 degrees (or more) on valley bottoms. One of the many joys of winter forecasting in Interior Alaska

Fort Yukon Sunshine.

Here's a time lapse from Fort Yukon today, from the FAA's south view. At the AWOS, the low temperature this morning was -49F, high so far today -47F.

Deeper Cold?

This mornings ECMWF has quite a cold airmass, much colder than the current airmass, over Interior Alaska the middle of next week. That purple blob over most of the Alaska mainland is -24C or colder at 850mb, which is more than 10C colder than it is now. The GFS is not so cold.

Inversion has weakened

Here are the two most recent soundings from the Airport. Thanks to cooling aloft, the inversion has weaken significantly this morning. Here on Keystone Ridge its about 15 degrees cooler than the same time Wednesday. In the valleys its zero to 5 degrees cooler. At 10am, 9 below on Keystone Ridge, 30 below at Goldstream Creek, a mere 21 degree inversion. It is in the mid-30s below in the North Pole area.

Slow Cooling

Today's RAOBS series show only a little bit of cooling at the surface between 3am and 3pm, but more substantial cooling above about 200 meters above the valley floor. Winds here at Keystone Ridge have diminished quite a bit; my neighbor recorded a peak wind of 35 mph Tuesday evening, just before 8pm. Models are forecasting quite a bit of cooling aloft over the next couple of days. I'd guess that Fairbanks International may see the first 40 below of the season sometime late Thursday night or more likely on Friday.

Building inversion

The inversion has steepened overnight, with temperatures in the valleys running in the 20s below and higher hills near 10 above. Here at Keystone Ridge the temperature jump from 0F at 5am to +6F by 630am as a bit of a breeze picked up. At 6am the reported extremes were -26 at Fort Wainwright and +9F at Clearly Summit.

4pm Update: The inversion has steepened even more, with "nose" of the low level inversion) at about 135 meters AGL at 3pm) some 14C warmer than the surface. The small decrease in temperature above the "nose is due to mixing from wind: here at Keystone Ridge snow blowing out of the trees, and if the wind turbine wasn't still stuck frozen from the rain, we'd be making power.

7pm Update: Whoa hoo…about 5pm winds to 25 mph or so unstuck the wind mill…now +12F and making electric. And an aurora out to boot.

Arctic Heat

This plot from the Climate Prediction Center plots daily temperatures and the 31 day running anomalies. The sustained warmth this autumn is really amazing; all due to lack of sea ice.

Slight Scary

Saturday morning forecast from the ECMWF for next Saturday morning (Dec 11). This would be pretty cold for Interior Alaska, but that's not the scary part. The rain last month was produced by a big high aloft that was of similar strength and in a similar position (a little farther east though) before moving into the North Pacific. But what are the odds, right?

Color field is 850mb temps, contours 500 mb heights.

Temperature Roller Coaster

Temperatures have been on something of a roller coaster the last couple days, with valleys and hills sometimes moving in different directions. Thursday afternoon and early evening temperatures fell sharply in the hills even as valleys warmed a bit. Then warming as an occlusion from a Bering Sea low moved into the area. The trough came through early Saturday morning, with a sharp fall at Keystone Ridge between 5 and 6am, but with no reflection at all in the valley. Mid-morning Saturday, Keystone Ridge is cooler than the airport. That is quite infrequent this time of year when it's not snowing.

Dramatic Low Level Cooling

The boundary layer cooled dramatically Thursday, probably in response to weak vertical motion from a Gulf of Alaska storm that has spread high clouds across the area.

While valley temperatures have been very slowly rising all day, temperatures having been falling at elevation. Here on Keystone Ridge it's been down by 12 below, while at the RAWS Caribou Peak was at +6F as late as 7am, while by 4pm it was down to -6F.

Morning Lows

A bit warmer in the Fairbanks area this morning, with temperatures mostly 20 to 30 below in valleys. However, it has cooled off in the eastern Interior and along the upper Yukon River. Chicken Coop came in with a low of 48 below, which I think is the lowest reliable temperature in Alaska so far this winter. Northway had 45 below. The NPS automated station at Coal Creek, between Eagle and Circle, had 45 below. On the Yukon Flats, the somewhat less reliable, but probably reasonable Chalkyitisk RAWS had 47 below and the Beaver Creek RAWS 46 below.

November Summary

What I did on my day off…

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
1235 PM AKST WED DEC 1 2010

...FAIRBANKS WEATHER SUMMARY FOR NOVEMBER...

NOVEMBER 2010 WILL LONG BE REMEMBERED BY FAIRBANKS RESIDENTS FOR THE
PROLONGED RAINFALL NOVEMBER 22ND TO 24TH THAT NEARLY CLOSED DOWN
THE AREA IN THE DAYS LEADING UP TO THANKSGIVING. THE RAIN PRODUCED
A THICK LAYER OF ICE ON ROADS AND MADE TRAVELING EXTREMELY
HAZARDOUS FOR SEVERAL DAYS. BOTH FAIRBANKS NORTH STAR BOROUGH
SCHOOLS AND THE UNIVERSITY OF ALASKA FAIRBANKS CANCELLED
CLASSES...MANY OFFICES CLOSED AS DID SOME BUSINESSES. ON SOME
SHADED SECONDARY ROADS...THE ICE FROM THIS RAINFALL WILL NOT BE
GONE UNTIL IT MELTS AWAY IN LATE MARCH OR EARLY APRIL.

SOUTHWESTERLY WINDS ALOFT BROUGHT MOIST SUBTROPICAL AIR FROM JUST
NORTH OF HAWAII INTO INTERIOR ALASKA. RAIN FELL...WITH ONLY A
SHORT BREAK...FOR TWO STRAIGHT DAYS. DURING THIS TIME 0.95 INCHES
OF RAIN FELL...INCLUDING 0.69 INCHES IN 24 HOURS. THIS IS THE
SECOND GREATEST RAINFALL DURING THE WINTER IN FAIRBANKS. ONLY
JANUARY 20 1937 HAD MORE...WHEN 0.99 INCHES OF RAIN FELL ON TOP OF
MORE THAN 26 INCHES OF NEW SNOW. THE 39 HOURS OF CONTINUOUS
RAINFALL APPEARS TO BE RECORD FOR LONGEST RAINFALL DURING THE
WINTER IN FAIRBANKS.

TOTAL PRECIPITATION FOR THE MONTH WAS 1.71 INCHES...THE
HIGHEST NOVEMBER IN 40 YEARS AND THE FIFTH HIGHEST NOVEMBER
PRECIPITATION OF RECORD.

TEMPERATURE-WISE...MILD WEATHER PREVAILED MOST OF THE MONTH...WITH 25
OF 30 DAYS AVERAGING WARMER THAN NORMAL. ONLY THE LAST TWO DAYS OF
THE MONTH FEATURED WELL BELOW NORMAL TEMPERATURES. FOR THE
MONTH AS A WHOLE...THE AVERAGE HIGH TEMPERATURE WAS 19 DEGREES AND
THE AVERAGE LOW 5 ABOVE. THE AVERAGE TEMPERATURE OF 11.9 DEGREES
WAS 9.6 DEGREES ABOVE NORMAL. THIS IS THE 13TH WARMEST NOVEMBER IN
106 YEARS OF RECORDS...AND THE SECOND WARMEST IN THE PAST 30
YEARS. THE HIGH TEMPERATURE FOR THE MONTH WAS 37 DEGREES ON THE
3RD. ONLY NINE DAYS HAD LOW TEMPERATURES OF ZERO OR LOWER...WHICH
IS LESS THAN HALF THE AVERAGE...AND THE LOW FOR THE MONTH WAS
32 BELOW ON THE 30TH. SOME OF THE NORMALLY COLDER AREAS AROUND
NORTH POLE WERE NEAR 40 BELOW ON THE 30TH.

DURING THE RAIN STORM...THE TEMPERATURE REMAINED ABOVE FREEZING AT
THE AIRPORT FOR 49 CONSECUTIVE HOURS. THIS APPEARS TO BE THE
LONGEST STREAK OF CONTINUOUSLY ABOVE FREEZING TEMPERATURES IN
FAIRBANKS DURING WINTER SINCE HOURLY WEATHER OBSERVATIONS BEGAN IN
MARCH 1941. HOWEVER...IN BOTH DECEMBER 1934 AND AGAIN IN NOVEMBER
1935 THERE APPEAR TO LONGER STRETCHES OF ABOVE FREEZING
TEMPERATURES...THOUGH THE EXACT DURATIONS ARE NOT KNOWN.

TOTAL SNOWFALL FOR THE MONTH AT THE AIRPORT OF 11.6 INCHES WAS
ENOUGH TO MAKE THIS THE SNOWIEST MONTH SINCE MARCH 2009...BUT WAS
STILL A COUPLE INCHES BELOW NORMAL. SNOWFALL WAS CONSIDERABLY
HIGHER TO THE NORTH OF TOWN....WITH 19.7 INCHES FOR THE MONTH AT THE
KEYSTONE RIDGE WEATHER STATION...NEAR MURPHY DOME...AND OVER 26
INCHES NEAR CHATANIKA.

THE SAME HIGH PRESSURE ALOFT THAT WAS EVENTUALLY RESPONSIBLE FOR
THE RAIN ALSO BROUGHT THE HIGHEST NOVEMBER PRESSURE OF RECORD IN
FAIRBANKS ON THE 16TH...WHEN THE PRESSURE REACHED 31.04 INCHES.