Here's a plot of the Fairbanks soundings from Sunday and Monday afternoons. The primary item of interest here is that both days featured lots of sunshine and very little wind. Monday especially was almost cloud free. This nicely illustrates that even though the maximum solar elevation is now above 15 degrees, it's still not enough to mix out the boundary layer. Another week to ten days should do it.
I'm waiting for that first evidence of solar induced snow melt. Not from entrained dark materials, but affecting white reflective snow.
ReplyDeleteAs you say...soon.
Wearing thin black clothing while walking the dog indicates the heat is there and increasing, even at this still low angle on a cloudless day.
Gary
Today (2/27/13) saw first evidence of melting...+28F and the sun's a cooking away at the snow.
DeleteSoon the flies will be a buzzin' Yea, right.
Gary
Rick,
ReplyDeleteIt sounds like the ability of the sun to mix out the inversion is a pretty reliable feature of the calendar and of the season. Is it reasonable then to say that "winter" in Fairbanks is the season marked by continuous inversion when skies are clear and winds calm? This could be an alternative definition to add to the lists you published last month... although perhaps more of a symptom than a definition.
Richard
Richard,
ReplyDeleteYes, that "afternoon inversion despite full sunshine" is part of my alternate definitions, and is a primary one marking the end of "late winter" and the start of "early spring".
Many other places in Alaska experience minor daily breezes associated with "adequate" solar heating that mixes the winter temp inversion. The solar angle is critical, as is the location's albedo.
ReplyDeleteFairbanks is a relatively non-windy place subject to temp inversion for several reasons. Too bad E. T. Barnette's boat didn't make it's intended destination.
Gary
Gary,
DeleteYou raise a point that has long been a pet peeve of mine, in the Fairbanks is by no means representative of the wind regime in Interior in winter. Fairbanks proper is unusually "unwindy", but because Fairbanks is the population center, this regularly gets extrapolated to "it's always calm in the winter in the Interior". I should put up a post about this.
Rick
Thanks to this Blog and other items you've noted (the Tanana Jet and remote wx stations reporting in the vicinity), we're made aware of nearby daily breezes Fairbanks proper often never experiences.
DeleteFor example, Google "Mesonet Weather Alaska" and select "All". Zoom in to see the surface wind values from nearby stations compared to Fairbanks airport.
Same for cold. We're overrun at the surface with sinking cold air from nearby terrain and valleys. Any breeze that affects us tends to diffuse the resultant inversion.
Climbing through the inversion in a plane to warmer air a few hundred feet above is a daily event on calm winter days. That, and wind, are why folks live in the hills surrounding town.
Gary
Better Mesonet/Mesowest link. Select "All" plus any additional values desired:
Deletehttp://www.wrh.noaa.gov/mesowest/gmap.php?zoom=4&extents=50.488302,-172.089844,72.893802,-130.960937&density=1
Gary
One more obs...Fairbanks probably sits in "wind eddy" during low surface wind velocities from certain directions (mainly SE/S/SW) when the winter inversion is strong.
ReplyDeleteFor example, ever been on a river or lake where the current or wind driven waves are moving along the shoreline? When they hit an eddy caused by a bank disturbance, or an adjacent side channel/bay, the current circulates through the anomaly in a slow circular fashion...round and round...instead of flowing through and out the other side.
At times it can be blowing to the south of town, and yet in Fairbanks, depending on direction, the prevailing surface winds are circulating all around the clock if at all. The horsehoe shaped hills around town may help create this pattern, like in the water mentioned above. Stronger winds will blow on through, however.
Gary
Today 3/7/13 at ~0800 AM the winds at Fairbanks International Airport were reported as calm, and the temp was -4F. Just a few miles to the south at the Blair Lakes RAWS (El 790') the temp was +19F with winds 19G29. The Nenana airport (El 361') to our SW was reporting +16F with winds 16G24. A weather system and resultant pressure gradient is approaching from the south causing the Tanana Jet to form and drive the wind and temp changes
ReplyDeleteIn contrast, the winds at valley locations in the immediate Fairbanks bowl (the wind eddy suggested above) are minimal and from varying directions, and temps are similar to the airport's. We have our own weather world in town this morning.
Gary