Tuesday, November 30, 2010

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

Monday, November 29, 2010

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.


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.

Sunday, November 28, 2010

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)

Saturday, November 27, 2010

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.

Friday, November 26, 2010

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.

Wednesday, November 24, 2010

Rainfall Amounts

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

430 PM AKST WED NOV 24 2010





MCGRATH.................................2.10 INCHES
LAKE MINCHUMINA...............1.63 INCHES
NENANA...................................1.52 INCHES
ESTER........................................1.16 INCHES
UAF WEST RIDGE....................0.99 INCHES
TANANA...................................0.99 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.

Tuesday, November 23, 2010

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


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.


Monday, November 22, 2010

Rainfall so far

Some event total rain amounts

Updated through 10pm AST:

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

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"

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

Sunday, November 21, 2010

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.

Saturday, November 20, 2010

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.

Friday, November 19, 2010

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

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.

Thursday, November 18, 2010

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.

Wednesday, November 17, 2010

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.

Tuesday, November 16, 2010

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.

Monday, November 15, 2010

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.

Sunday, November 14, 2010

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.

Saturday, November 13, 2010

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.

Thursday, November 11, 2010

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.

Wednesday, November 10, 2010

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

Tuesday, November 9, 2010

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"

Monday, November 8, 2010

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.

Sunday, November 7, 2010

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.

Saturday, November 6, 2010

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.


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.

Friday, November 5, 2010

November Sunshine

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

Tuesday, November 2, 2010

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.

Sea Ice Arriving

Webcam shot from Barrow this morning; sea ice finally arriving/forming. NE winds with temps around +5F.