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.

Afternoon Inversion

About 160 meters worth of cold air, then isothermal just above -20C. Airport managed a high of 23 below; 2 below here at Keystone Ridge. Just like the RAOB says.

Healthy Inversion

The inversion has become more shallow and stronger since Monday afternoon.
Through 9am, overnite low temperatures include:

East Fort Wainwight: -35F
Eielson AFB -34F
Goldstream Creek: -32F
Fairbanks Airport: -31F
UAF West Ridge -27F

Meanwhile…at elevation:
McGrath Raod CWOP: -12F
Nenana Hills RWIS (near Skinny Dicks) -10F
Cleary Summit: -7F
Ester Dome CWOP -7F
Keystone Ridge: -5F

The Woodsmoke Weather Underground station near North Pole has been to -38F so far

Inversion Structure

The Monday afternoon sounding shows that the cold air is not razor thin; rather, there is about 250 meters of cold air. Here on Keystone Ridge were are well into the milder air, so temps having been between 1 above and 2 below this 9AM. It will be interesting to see if the cold air sloshes uphill over the next couple of days.

Inversions

Clouds finally broke up Sunday evening, allowing a nice inversion to develop by Monday morning. As of 830am, 23 below at Goldstream Creek and 2 below at Keystone Ridge. One of the North Pole area Weather Underground stations is at 28 below and the location Two Rivers WxUnderground site is 29 below.

Winter Lives

Clouds cleared for a while overnight along the south slopes of the Brooks Range, allowing Arctic Village to bottom out at 29 below, and Coldfoot has been down to 27 below. Widespread cold in Siberia now too, with 64 below at Oymyakon Sunday morning (local time) and, update: 65 below Monday morning (local time).

Photo of the noontime sun scraping above the mountains at Denali National Park (from the FAA)

Even more snow

Substantial variation in snowfall around the area since the colder air beganning moving in in earnest Thursday morning.

Here at Keystone Ridge, there has been 8.4 inches of snow Thursday through Saturday morning, including 5.4 inches between Friday morning and Saturday morning. In contrast, the Goldstream Creek Coop station has had 3.1 inches of snow Thursday morning through Saturday morning. The Airport has had 3.3 inches of snow since Thursday morning.

Slow Clearing

2pm AST Infrared NOAA-19 Polar Orbiter image shows only limited clearing over the Interior. The 3pm AST ROAB should less than a degree of cooling in the boundary layer from the morning sounding.

Snow is nice

This morning's Feng Yun Polar Orbiter shows a fairly disorganized cloud pattern over Interior Alaska.

Snow here on Keystone Ridge totals over 3 inches of fluffy powder now in the past two days; less in town. We'll take it, as it covers up the ice from the rain and provides a based for traction. The ice will return, though it may be March. Like the Fruit of the Month club, freezing rain is the gift that keeps on giving.

The airmass has cooled to smartly but low level temperatures are forecast to change little until Saturday, when it cools a bit more. At the surface, the clouds and snow will keep temperatures in valleys above normal. Once it clears though, the 20 and 30 below temperatures will quickly materialize.

Rainfall Amounts

From a very day shift…some of these totals include liquid amounts after the rain was mixing with snow.

PUBLIC INFORMATION STATEMENT...CORRECTED
NATIONAL WEATHER SERVICE FAIRBANKS AK
430 PM AKST WED NOV 24 2010

...SECOND HIGHEST WINTER RAINFALL STORM TOTAL ON RECORD IN FAIRBANKS...

AS OF 10AM WEDNESDAY A TOTAL OF 0.94 INCHES OF RAIN AND FREEZING
RAIN HAD FALLEN AT THE FAIRBANKS INTERNATIONAL AIRPORT SINCE
MONDAY. THIS IS THE SECOND GREATEST WINTER RAINFALL OF RECORD FOR
FAIRBANKS. THE GREATEST WINTER RAINFALL OF RECORD IN FAIRBANKS
OCCURRED ON JANUARY 20TH 1937 WHEN 0.99 INCHES OF RAIN WAS
REPORTED. THESE TWO EVENTS ARE THE ONLY OCCURRENCES OF MORE THAN
HALF AN INCH OF RAIN DURING THE PERIOD FROM NOVEMBER THROUGH
MARCH.

COOLER AIR IS SLOWLY MOVING INTO THE REGION FROM THE WEST AND WILL
CONTINUE TO DO SO THROUGH THE EARLY PART OF THE WEEKEND.

BELOW ARE SOME RAINFALL TOTALS FROM MONDAY THE BEGINNING OF THE
EVENT THROUGH 10AM WEDNESDAY:

MCGRATH.................................2.10 INCHES
LAKE MINCHUMINA...............1.63 INCHES
NENANA...................................1.52 INCHES
KEYSTONE RIDGE (MURPHY DOME)............1.37 INCHES
ESTER........................................1.16 INCHES
UAF WEST RIDGE....................0.99 INCHES
TANANA...................................0.99 INCHES
FAIRBANKS AIRPORT.............0.94 INCHES
EAST FT WAINWRIGHT.............0.92 INCHES
GOLDSTREAM CREEK.............0.90 INCHES
EIELSON AFB...........................0.63 INCHES

Portrait of Rain

Here's the NCEP reanalysis of 500 mb heights for 10am AST on Monday. It's a classic pattern for heavy precip in Interior Alaska: big ridge in the Gulf of Alaska and southwest flow that goes around the Alaska Range.

Rain Records again

At Fairbanks International Airport:

Total rainfall: 0.94 inches between 5am Monday and 4am Wednesday. This is the greatest November rainfall of record and the second greatest winter rainfall, just short of the 0.99 inches on January 20, 1937. The maximum 24 hour precipitation was 0.68 inches between 6am Monday and 6am Tuesday, This is well short of the November 24 hour record precip of 0.94 inches in 1935 and has been exceeded several other times as well.

Rain fell continuously from 517am Monday until 808pm Tuesday, and then again from 1009pm Tuesday until 327am Wednesday. Measurable rain fell for 31 consecutive hours; every hour between 6am Monday and 1pm Tuesday. More research will be needed to absolutely confirm this, but is most likely the longest period of record of straight rain (not mixed rain and snow) during the winter in Fairbanks.

Rainfall Totals

Some rainfall totals since Sunday night/Monday morning

Updated at Tuesday 3pm AST

Gilmore Creek in Fox: 0.82 inches (3pm)
Keystone Ridge 1.02 inches (noon)
Ester 0.87 inches (9am)
UAF West Ridge 0.73 inches (9am)
Goldstream Creek 0.64 inches (7am)

Tanana: 0.76 inches (noon)
Fairbanks 0.79 inches 3pm)
Nenana 1.19 inches (3pm)
McGrath 1.63 inches (22-23rd)
Minchumina 1.23 inches (9am)

Rain Records

FYI…

The following records have been set at the Fairbanks airport:

Through 10am AST total rainfall: 0.73 inches; second greatest winter rainfall of record (0.99 inches Jan 20, 1937) and these two events are the only occurrences of more than half an inch of rain November through March (observations since Sept 1904)

24 hour rainfall 5am Monday-5am Tuesday: 0.66 inches; this is the greatest 24 hour November rainfall of record

Precip total for Nov 22 of 0.50 inches (not 0.54 inches) is a record for the date. Previous record 0.21 inches in 1925.

The November maximum 24 hour precip record was not broken; still 0.84 inches set Nov 27-28, 1970.

Rick

Rainfall so far

Some event total rain amounts

Updated through 10pm AST:

ASOS
Delta Junction: 0.16"
Fairbanks Airport: 0.45"
Tanana: 0.46"
McGrath: 1.12" (24 hour total)
Nenana: 0.88"

COOP
Fairbanks area…
Keystone Ridge 0.60" (6pm)
East Farmers Loop 0.43" (10pm)
Golstream Valley Bottom 0.41 (10pm)
Aurora 0.37" (9pm)
Fairbanks CRN at Gilmore Creek 0.35"

Elsewhere…
Kobe Hill (near Clear) 0.51" (5pm)
Clear 0.60" (8pm)
Galena 0.64" (6pm)
Whitestone Farms (near Big Delta) 0.30"
Tok 0.00" (8pm)

Synoptic Situation

As is typical with most big precip events in the winter in Fairbanks, this is not tied to a storm. Rather, precipitation is tied to deep moisture rotating around a North Pacific ridge.

Fairbanks Closed

As of 3pm AST 0.29" of rain has fallen at the Airport, the greatest single day winter rain in Fairbanks since January 20, 1963 and the greatest November rain since Nov 24, 1936.
Here at Keystone Ridge 0.39" so far. The Fairbanks Daily News-Miner details the closing of Fairbanks

Record wamth in Barrow

By 310am Sunday Barrow has already set a new record high for November 21st: 32F. The old record of 31F was set in 1926.

Warm-up underway

The Saturday afternoon sounding from Fairbanks shows warm air pouring in aloft: in the lowest 10,000' of the atmosphere. the temperature only varies from -6 to -1C. Image from U. of Wy.

Winter Rains in Fairbanks

With rain on the way for Monday, here is list of the major winter rain events in Fairbanks:

Feb 8-10, 2003: 0.29 inches of rain with trace of snow. Schools closed for two days due to very icy roads.

Dec 24, 1970: 0.22 inches precip mostly rain; 0.6 inches snow

Jan 20, 1963: 0.44 inches rain, trace snow

Jan 20, 1937: 0.99 inches of rain, no snow and temps in the mid 30s

Jan 10, 1937: 0.20 inches then changed to snow

Nov 24, 1936: 0.42 inches rain, mixed with snow for a while in the evening.

Feb 6-7, 1923: 0.30 inches of precip, Trace snow, temps in the 30s

Mar 6-7, 1921: 0.34 inches rain, trace snow

These are all of the events that I know of between November 15th and March 31st that produced two-tenths of an inch or more of rain.

Through November 18th, average temperature departure for the month thus far:
Barrow: +8.7F
Fairbanks: +7.1F
Anchorage: +5.5F
Valdez: +4.9F with a whooping 2.3" of snow for the month!
Kotzebue: +2.1F
McGrath: +1.9F
Nome: -1.3F
Bethel:-2.4F

So for Mainland Alaska, southwest cool, elsewhere mild. A classic El Niño pattern. Except wait, it's a moderate La Niña! Note that Barrow is reflecting the decreased Arctic sea-ice coverage; historically Barrow temps don't show much correlation with ENSO.

The ever changing Fairbanks rain threat

Numerical guidance is coming into better agreement (as usually happens) on the rain threat for Sunday afternoon/night. There is general consensus now that a cold front will move across the Interior as a trough aloft breaks through the ridge. In this scenario, precipitation would start as rain, changing to snow before ending, though the period of snow, especially in valleys, would not be long. The 18Z GFS is very aggressive with precip amounts. In any event, odds are that Monday morning is going to be a serious mess.

Thurday Snowfall

Snowfalls Thursday around the Fairbanks were pretty tame, though we'll take what we can get:

Mile 42 Steese: 4.0"
Keystone Ridge: 2.3"
Goldstream Valley Bottom: 2.0"
East Fort Wainwright: 2.0"
Woodsmoke (off Badger Road) 2.0"
East Farmers Loop 1.7"
UAF West Ridge: 1.6"
North Pole: 1.6"
Fairbanks Airport: 0.8"

The big winner for snow was Eagle: 9.0" on 0.19" liquid. If this is correct, this 47-1 ratio is in the extreme category for "fluffy snow"

Models continue to vacillate about rain Sunday afternoon through Monday, though no more talk of half an inch! This mornings GFS has rain changing to snow starting Sunday afternoon, with a couple tenths of an inch precip. So we'll see.

Update on Rain for Fairbanks

The morning run of the GFS has backed WAY off on rain for Fairbanks-land late in the weekend, instead opting for a climatologically much more likely scenario of developing a deeper low in the Bering Sea and a run of the mill Chinook over the Interior. Through Wednesday, in spite of two days with slightly below normal temperatures, the November mean temperature was 7 degrees above normal. This pattern will only boast that; 2002 it aint, but it's going to wind up a very mild autumn.

Rain for Fairbanks? Oh No!

Models are increasingly pointing at a major rain event for the central Interior Sunday PM into Monday. Here is the GFS forecast from 00Z Thu valid 3am Monday: 0C line at 850mb is north of Fairbanks, and the 1000-850mb thickness is 1319 gpm, with more than half inch of precip forecast between Sunday evening and noon Monday. That much rain between November and March has occurred at least once (January 1936), but maybe only once, in the 105 years of weather observations in Fairbanks. This could be bad.

North Slope Blizzard

Here is the 10am AST Wednesday Northern Alaska Weather Depiction chart from the Alaska Aviation Weather Unit. Note the 30 to 40 knot sustained winds on the North Slope from Prudhoe Bay westward . Unusually for the North Slope, there is a lot of new snow falling in the strong warm advection over the top of the ridge, though the 40-1 raito snow used at Barrow at 18z is unrealistic.

More on the record high pressure

Here is the Environment Canada analysis for 3am Wednesday. The highest reliable MSLP I've found so far is 1053.0mb at Delta Junction. The 1055.9mb at Galena (an FAA AWIS) looks much too high compared to Kaltag (an ASOS) and Ruby (an AWIS).

The record high pressure over the Interior is helping to fuel a major league blizzard on the North Slope.

A New Record

At 653pm AST Tuesday, the mean sea-level pressure at Fairbanks International was 1049.8mb/31.00 inches. A new record for November. Destined to go higher too.

Update: Mean Sea-Level Pressure maxed out at Fairbanks at 1051.4mb/31.05" at 1253am AST Wednesday. The previous record was 1047.8mb/30.94" set on Nov 26, 1966.

Colder with the Big High

Fairbanks is poised to set a new November record high pressure later Tuesday or early Wednesday, with the high extending across much of mainland Alaska, as seen in this 9am analysis from Environment Canada.

Temperatures fell smartly in the areas with clear skies to the lowest levels of the season many places. The lowest temperatures were along the south side of the Brooks Rage: 39 below at the Coldfoot Snotel, 35 below at Chandalar Lake, 31 below at Bettles. Tonight will be the coldest night on the season so far in Fairbanks-land.

More Snow

Snow Sunday night and Monday was as much or more than fell Saturday in most areas, though based on time of observations the amounts are getting harder to sort out. At any rate, here's whats in thus far:

East Fort Wainwright: 2.5"
UAF West Ridge: 1.8"
Keystone Ridge: 1.7"
Goldstream Creek: 1.6"

Healy reported 8" of snow on 0.36" liquid' not implausible but twice as much as at Denali Park HQ.

Busy weather coming up later this week: lloks to be a major west wind storm for the Chukchi Sea coast. It's early in the year for Ivu problems, but this is a good set-up. Stayed tuned.

New Snow

A general 1 to 3 inches around the Fairbanks area Saturday, though most reports were closer to one inch. Two Rivers and Chena Hot Springs area might be at the upper end too as winds aloft were southwest.

Mile 43 Steese: 3.0"
Keystone Ridge: 1.6"
North Pole" 1.2"
UAF West Ridge: 1.1"
East Farmers Loop: 1.0"
Fairbanks Airport: 0.9"

Meanwhile, a high temp of 36F at Eagle Saturday.

Big High Coming

I usually don't have much to say about models here, but what the heck. For some days most of the models have been forecasting all-time record high pressure over the central Interior. Recent runs have backed off some, but are still close. Here is Saturday morning's GFS valid 3am Tue. That's about a 1048mb high over the Interior. Inversions should be spectacular by mid-week.

Consistent Warmth

Here's a plot of the 850mb temperature at Fairbanks for the past month. This is most notable for the lack of extremes. Normals decline from -5C on Oct 10 to -10C today.

Around the (Sub) Arctic

Low temperatures for Wednesday (through mid-afternoon Alaska Time)

Russia: -44F at Oymyakon (eastern Siberia)
Alaska: -15F at Selawik
Canada, Northwest Territories: -19F at Thomsen River (northern Banks Island)
Canada, Nunavut: -34F at Eureka (central Ellesmere Island)
Greenland: -48F at Summit (near the highest point on the ice cap)
Norway: -18F at Karasjok
Sweden: -23F at Nikkaluokta
Finland -10F at Kevo

Snow Depths around the Interior

It;s not very often that Galena gets top spot, but here is a sampling of snow depths in the Interior as of Tuesday morning:

Galena: 11"
McGrath 10"
Bettles: 7"
Chandalar Lake: 7"
Northway: 6"
Fairbanks: 5"
Tok: 5"
Denali Park HQ: 4"
Dry Creek: 2"
Chicken: 1"

SNOTEL sites:
Coldfoot: 5"
Eagle Summit: 5"
Fort Yukon 5"

October Mean 500 mb Heights

The mean October 500 mb height field from the NCEP reanalysis, showing the persistent low in the eastern Bering Sea, with south flow over much of mainland Alaska.

Inversion Changes

Significant structural changes in the Fairbanks boundary layer temperature profile Monday morning compared to Sunday morning. Sunday morning there a little more than 400 meters of cold air below the elevated inversion top. Monday morning, the lowest kilometer showed a typical radiation induced surface inversion.

Winter comes to Oymyakon

Low temperature this morning (Monday morning local time) of -42F at Oymyakon in eastern Siberia. This isn't the first day this season with a 40 below temperature; it was 43 below on Nov 2nd. Except for the Summit weather station on the Greenland Ice Cap, Oymyakon is the only regular weather station in the northern hemisphere to hit 40 below so far this early winter.

Freeze-up continues at Barrow

Early Sunday afternoon webcam shot from Barrow; still a little open water visible offshore. The National Snow and Ice Data Center Arctic Sea Ice analysis for October showed that inspite of a large seasonal increase in ice coverage, total sea ice extent in the Arctic remains very low for this time of year.

Balmy Bliss

It hasn't really been continuously warmer than normal for the last three months in Fairbanks, it just feels like it. Note temperatures are in degrees C; image from the Climate Prediction Center. With the lack of precipitation, radiational inversions are helping keep valley based temperatures closer to normal than the overall airmass, i.e. hill temperatures are running even more consistently and farther above normal than this plot would suggest.

Inversion

Clear skies, a ridge aloft and the calendar says Novmeber: the outcome is predictable. Lows Saturday morning of 3 below at Goldstream Creek and 1 below at East Fork Wainwright. Meanwhile, overnight temperatures rising overnight in the hills. High at 7am Saturday at Keystone Ridge of 32F, while Cleary Summit's been up to 31F.

November Sunshine

Sunny late Friday morning at Nenana. Note the skimpy snow cover.

What Declining Sea Ice Actually Means on the Ground

The lack of sea ice in October in recent years at Barrow is having a major impact on the climate. Here is a plot of the mean October temperature in Barrow since 1920. Two things to note. First, the running mean is now higher than it has been in the past 85 years. Second, there is very little variation: the bottom brown line is the 5 year running standard deviation, which has collapsed. This is completely attributable to the moderating influence of the water.