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.