Location: New York
Author: Weather 2000, Inc.
Date: Tuesday, February 26, 2008
Six climate perspectives as we enter final 6 weeks of Winter Season:
1.) Besides the continuation of a NET colder pattern for the Nation, temperature volatility & fluctuations will also be continuing.
2.) '07-'08 Broken Record: Almost every new Polar Waves that dives into the Midwest focal point (around the Hudson Bay Vortex) will also be accompanied by a brief "See-Saw" of milder (or moderated) temperatures surging up the Eastern States, until the Polar air filters to the Atlantic.
3.) With the aforementioned See-Saw along with the absence of true Greenland Blocking, a computer model projection initialized or centered on one of these milder ripples could easily sing a different tune at any time. So model fickleness and unreliability beyond 6 days will continue to be the trademarks of this Winter Season, and services that rely on the models correspondingly do the "bold then back-peddle outlook tango" every couple of days.
4.) Cyclogenesis and storm tracks will once again shift to an even higher gear, from the Plains the East Coast, reminiscent of some December 2007 precipitation themes. These storms' associated wind fields and snow-pack will continue to disguise some "cold" results beneath the detection of airport weather stations and plain Heating Degree Days.
5.) With the exceptionally large stores of Polar/Arctic Air still available in Canada and across the Arctic Circle for this time of year, if the same Teleconnection delivery mechanisms remain in place upcoming weeks could pack a punch relative to average. The final week of February through first-Half of March have been thermally rather benign the past few years for the U.S., so you should anticipate some significant 'year-on-year' and 'versus 5-year average', contrasts.
6.) Still a matter of when, not if. Long before this Season got going there was an anticipated quantity of cold air (HDD's + apparent temperatures) that we expected to enter the U.S. this Winter from start to finish. As you know from our pre-Season research, this was going to have a maximum impact across the Midwest/North-Central States, and a minimum impact across the Gulf Coast/Southeast States. Considering from the past 15 years only the historic 2002-2003 and 1995-1996 Winter Seasons were supposed to rival/surpass the 2007-2008 Winter, the U.S. is still "due" some decent HDD tallies which we'll experience one way or another over the next 6 weeks.
National Snow Coverage as of February 24, in recent history:
2004: 29.9%
2005: 26.8%
2006: 29.5%
2007: 34.8%
2008: 47.2%
Comment: The entire North American Snow/Ice coverage is currently the most observed in many years, helping to reproduce fresh pools of Polar & Arctic Air, and help invigorate those air masses when they do enter the contiguous U.S., beneath the 850 mb level which services' model synopses depict.
On Wednesday February 27 we will be issuing our latest ENSO Report, outlining our climate research and monthly Temperature & Precipitation expectations for North American (with International highlights), for the balance of the Winter, Spring and through to 2008 Summer.
Words of caution: The La Niņa phenomenon and its hemispheric process have 3 main post-Winter influences of concern to North America: (1) Encouraging "Spring" Severe Weather outbreaks, (2) Encouraging a robust Summer Monsoon for the Southwestern U.S., and (3) Encouraging Tropical Cyclone development for the Atlantic Basin. Legitimate and proper Climate Science knows that ENSO (El Niņo/La Niņo0 is not a driver of U.S. Summer temperature patterns like it can be in the Winter Season, so be wary of any Summer outlook that utilizes Summer La Niņa status as a defense (diagrams, charts and pretty maps not withstanding). In the end, being right for the wrong reasons might work out, but such "weather coin-flips" have dangerous consequences and hurts the science.
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