Saturday, January 19, 2013

One More Round of Interior Alaska Seasons

Okay, before moving on to actual numbers, here's my personal "integrated" seasonal definitions for Fairbanks-land. By integrated, I mean this takes into account astronomics, climate and events.

  • Early Winter: establishment of the permanent winter snow cover in October until mid-November. Roads are regularly icy and skies often quite cloudy. Most precipitation is snow but drizzle or very light rain from shallow clouds not that uncommon.
  • Core Winter: the dark time of year, mid-November until the end of January: potential for extreme inversion and of course deep cold. 
  • Late Winter: February through very early March: more sunshine, less snow. Daytime inversions weaken from the rapidly increasing solar heating but do not completely break without other forcing.
  • Early Spring: very early March until sustained melting commences, typically early April. Often clear for days on end and breezy even in town. The time of year to get out and "play in the snow".
  • Late Spring: early April until early to early to mid May: active snow melt and break-up. Ends at green-up. The sloppy season; crud emerges from the snow. Not the finest time in Fairbanks, but all the daylight is a delight after the dark winter.  Precipitation of any kind uncommon.
  • Early Summer: green-up until start of the deep convective season, typically early to mid May until very early June. Very light brief showers common.
  • High Summer: peak of the convective season, very early June until early-mid July. Highest frequency of hot days, and often all the rain comes as showers or thunderstorms.
  • Late Summer: the stratiform rain season, typically mid July to mid-late August. Often condensed to "August" in general conversation in Fairbanks, i.e. "it always rains for the Fair". Highest frequency of fog.
  • Early Autumn: late August until mid-late September: return of darkness at night, colors in trees and undergrowth. Ran frequency drops way down from late summer. The quintessential "crisp frosty nights and gorgeous sunny days" time of year (my personal favorite these days, just ahead of Late Winter).
  • Late Autumn: mid to late September until establishment of permanent winter snow cover. Changeable weather, most common time for "snow in the hills, rain in the valley" kind of weather. Increasing darkness yet all is brown: harder to see moose by the road without some snow cover.
So obviously these definition are generalizations and in some years differ. For example, in 2004 there never was a late summer in that a sustained period with regular stratiform rain never occurred. The super high aloft help almost all month and helped keep the record wildfire season going until in snowed in September.

1 comment:

  1. Maybe Rich we should let waterfowl anthropomorphically determine seasons. Seems like they, the long term transient residents, know best when to arrive and leave. Summer = good, Winter = bad.

    That's unless you're a resident duck on the Chena River, or one of Interior Alaska's spring fed streams like the Delta or Richardson Clearwater.

    Either way, days are lengthening and the Sun will soon have an influence on the Pineal Gland and its products.