March Ends on a Chilly Note

Much colder air moved into the central Interior Wednesday night, with Thursday afternoon temperatures 15 to 20 degrees cooler than the day before. And that was with of 100% sunshine, as the evening photo from UAF West Ridge shows the ground view. The NOAA-19 304pm visible image shows the view from above. High temperature for the last day of March 15F on Keystone Ridge and 21F at the Fairbanks Airport. April will start off on a chilly note: look for temperatures near 20 below in the cool valley spots by morning. No fooling. Photo credits: Alaska Climate Research Center, NWS Alaska Region

The Streak Ends

Snow started early Sunday evening in Fairbanks, ending the streak of precipitation free days at 28. This is the third longest sting of consecutive days without precipitation in Fairbanks since 1930. The longest is 33 days March and April 1993.

Power of the Sun

This month's sunny and dry weather has provided a vivid illustration of the increasing power of the sunshine. The graphic at the left plots daily max and min temperatures for the Airport and Keystone Ridge thus far in March. A couple of interesting items. First, inversion strength, as quantified by the spread in overnight low temperatures has been reasonably constant. However, high temperatures have been rising faster at the Airport, with the last week or so showing the standard (i.e. dry adiabatic) decrease in temperatures with elevation. This contrasts with early in the month, when the sunshine was unable to completely break the inversion.

Dry and Dangerous

Yesterday (Tuesday) was the 24th straight day with no precipitation at all at Fairbanks. This morning's 500mb analysis tells the story. Low flow, weak residual high aloft with a strong jet across the North Pacific. Plus, no moisture yet for convection.

The primary weather problem in Fairbanks area remains the freezing rain—from November. With dry and sunny weather for so long now, roads that had been snowpacked are now clear down to the ice. There has been patchy improvement the past few days as more pavement is exposed due to melting in some really sunny low elevation places, but other spots are just icier as water covers the ice surface. There was a 2-car fatal accident on Badger Road Monday afternoon directly attributable to ice from the November rain.

Above freezing in Fairbanks

The mid cloud cover was solid until early Saturday evening, then it cleared right out. So it's back in the sunshine Sunday, and a return of the 40 degree diurnal ranges. So, with a low of -3F this morning at the Fairbanks, the stage was set for the first above freezing temperature since January 2nd. And waalaa, the high through 4pm ADT has been 36F.

Here on the ridge, up to 31F today with some drips off the roof.

Photo from Alaska Climate Research Center at UAF, about 530 pm Sunday, looking south

Strange Sky

For the first time in almost three weeks, it's not sunny. The NOAA-19 polar orbiter infared image from 530am ADT Saturday shows an area of mid clouds west of Fairbanks-land. These have since moved in. What ever shall we do?

Tanana Sunrise

Sunrise Friday morning at Tanana from the FAA webcam. The sunny...cool and dry weather pattern looks to be changing...though not much threat of snow for most of the Interior. Temperatures are on the way up though.

Umiat Sunset

Mid-March sunset at Umiat, about 90 miles southwest of Prudhoe Bay. High today -18F, low this morning -39F.

Diurnal Ranges and Inversions

Big high pressure, surface and aloft, remains over northern Alaska. Almost every day has brought bright sunshine to Fairbanks-land with no more than some wisps of high clouds, and the temperature of the airmass overall is not changing much. So this is a good set-up to look at the differences in diurnal temperatures between the lowlands and the hills. Plotted on the right are the range between high and low temperatures from the Fairbanks Airport and Keystone Ridge each day so far this month. The airport has consistently had more than twice as big a temperature range, generally around a 40 degrees swing, while Keystone Ridge is averaging about an 18 degree daily change in temperature.

The reason for this is not that the sun is providing more heating on the valley floor that 1000 feet higher. Rather, strong valley based inversion continue to form overnight, but there is now enough local heating from the sun to break that inversion, so some of the the daily temperature range in the valley is simply mixing down the warmer air above.

Big High Aloft

Wednesday was the ninth consecutive day of nearly cloud free skies over the central Interior. Big high pressure aloft is responsible; 3pm AST Wednesday; analysis from Environment Canada.

Chilly morning in the Eastern Interior

Valley temperatures were in the 40s below in eastern Interior valleys Thursday morning, with lows of 45 below at Chicken, 44 below at Northway and Tok (the CWOP) and 40 below at Eagle. Still, bright and sunny. Image from Eagle, courtesy of the FAA.

In Fairbanks-land, 29 below at the Airport, 32 below at East Fort Wainwright and 35 below at Eielson AFB.

February

February 2011 will be long remembered in the annals of Fairbanks weather lore, with back to back storms that are close to "blizzards" as Fairbanks ever gets (which is to say, not that close). Still, 30 inches of snow any month in Fairbanks is a lot. Temperatures in the valley were actually not terribly far below normal, only 2.7 degrees at the Airport. Due to all the storminess, inversions were much weaker than normal, so it was much farther below normal at elevation. Here on Keystone Ridge, over seven degrees below normal for the month.

Digging Out

Three days later, and I have just finished shoveling my way to the road. The drifting was as much as I recall here on the ridge. Anyway, since Saturday clear and cold with high pressure in control. Down to 31 below at Fairbanks Airport this morning, and 38 below at Goldstream Creek. A more pleasant 12 below here on the ridge, although it appears it will not get above zero today, which is not shabby for the last day of February.

That's a Gradient

Environment Canada's surface analysis valid 3PM AST. That is one whale of pressure gradient across Alaska. 1047 mb high in the northwest Bering and 979 mb low over Banks Island. Maybe it will be windy.

Howling winds

Possibly the most impressive wind observation thus far:

Umiat RAWS at 223PM AST

Temperature -1F, west winds 45 gusting to 62 mph. That's a whole lot of wind for Umiat.

Update:

At 7pm AST Friday the Fairbanks Airport reported a peak wind of 53 mph. This is the strongest wind gust in February since a gust recorded was installed in 1985, and one of strongest any time outside of a thunderstorm.

Winds Aloft

Here's a snapshot of the VAD winds early Friday afternoon from the Pedro Dome NexRad Radar, high atop Pedro Dome, northeast of Fairbanks.

This shows 40 kts of wind at 3000 feet MSL (that's only a few hundred feet above the elevation of the radar) increasing to 50 kts at 6000' MSL. The most recent winds are on the right of the graphic, courtesy of the WeatherUnderground

Windy

The attached plot of surface observations from 1pm AST Friday, though corase, shows it windy from the Bering Strait to the Yukon border as a decent surface low tracks eastward north of the Arcti Coast, supported by roaring winds aloft. The Prudhoe Bay area has had winds gusting to around 60 mph since around midnight. It had been very mild; high temperature of 33F at Deadhorse on Thursday, but temperatures are now falling rapidly.

Here in Fairbanks, it looks like 3-6 inches of snow overnight is the rule. Although windy, there is much less drifting than the storm Sunday and Monday, as the snow is denser and temperatures much milder.

Calm before the storm

A shallow inversion has held all day Thursday in Fairbanks, keeping temps down well below freezing. Above the inversion the winds are roaring, with 55 mph winds at 850 mb on the 3pm AST RAOB. The Snotel on Eagle Summit has sustained winds almost 30 mph as of 6pm. This will work down to the ground when the front comes through later this evening, when temps will jump up before falling all day tomorrow.

Storm winding down

The storm is winding down now. but not before producing a 53 mph gust at the airport, where the storm total snowfall is 18.5 inches. At the left is the 3pm Monday surface analysis from Environment Canada. The the big storm exiting Interior Alaska? That's right, there isn't one. This is the classic pattern for heavy snow in the Fairbanks area: high pressure over the north Pacific/western Gulf of Alaska and southwest winds aloft. Of course, they don't all come with this much wind.

Heavy Snow

Update:
24 hours ending 3pm AST, snowfall at Fairbanks Airport is apparent 17.1 inches. This is, I believe, the second greatest 24 hour snowfall of record, exceeded only in February 1966.

Snowfall observations coming in quite remarkable, Fairbanks south and eastward. In the North Pole area there are reports of 14 to 17 inches of new snow since Sunday morning. The North Pole climate station, in operation since 1968, only as one day in February with 10 or more inches of snow, so this might be a new record there. For locations with obs back that far, the snowfall of February 11-12, 1966, in which Fairbanks Airport measured 20 inches in 24 hours, is the greatest storm 24 hour event of record.

Other reports include
Perkins Landing 16.5 inches (NWS employee)
UAF West Ridge Coop: 12.5 inches
Chatanika Coop: 12.0 inches
Goldstream Creek: 10.7 inches
Keystone Ridge 7.5 inches (as of noon)

More to come