US Weather Commentary

~ Summer heat appears in Southwest.....

~ Not much time for Spring in 2009.....

We've become accustomed to the "Seasonal Shift" this Decade, but 2009 is truly pushing the envelope. While sub-freezing temperatures at dawn are still plaguing half of the contiguous 48 States, and the Rockies/Northwest still have the highway plows working 2 weeks before May, the Southwest portion of the Nation is leap-frogging directly into some Summer heat.

Desert communities from Palm Springs to Needles to Phoenix could approach & break 100°F for a few days in the coming week; a noteworthy +10°F to +14°F anomaly range for this time of year.  This should not take the form of a classic Santa Ana Event, so coastal communities from Los Angeles to San Diego should only be modestly warmed into the 70's.  But Wild/Brush/Forest fire risk will be elevated across the region.

These simultaneous extremes are all translating to an unusually large accumulation of U.S. Total Degree Days [TDD] {HDDs + CDDs}, during what is typically a very benign shoulder month.  However, as discussed in the re-included sections below, Summer patterns (which could begin very early this year in May) will be different than these April developments, so be careful of extrapolating and be wary of the perennial Spring rumor mill.

National Snow Coverage as of April 16th, in recent history:

2004:   6.0%

2005:   6.5%

2006:   7.0%

2007: 10.8%

2008: 11.8%

2009: 13.5%

Special Reports to look forward to:

*  Throughout the Spring and upon request, we will be conducting "Forecasting the Summer Forecasters" commentary, reviewing what the popular Summer outlooks are likely to say, as well as the key pit-falls these short-term forecasters are falling into regarding the 2009 Summer Season.

* In late-April we will be issuing our annual summary, reminders, insights and advice, regarding the 2009 Hurricane Season.

* In late-April/early-May we will be issuing our perennial pre-Season FAQ [regarding the 2009 Summer], with answers to popular client questions in a sit-down format with our Chief Meteorologist. For more site-specific questions and concerns you may have, please peruse the following case-studies: http://www.weather2000.com/fcst_discussion.html

* Later in May, NOAA/NHC is scheduled to issue their first Hurricane Season Forecast of 2009 which will likely garner media, public and industry attention. 

Re-Included from previous discussions, for pertinence:

The 2008-2009 Winter Season was supposed to be early, long, anomalous and late according to our research, with impactful "bookends" {Nov-Dec and Mar-Apr}, and the hemisphere is certainly living up to its promise.  Just as many locations East of the Rockies experienced some of their earliest cold sine the 1990's, 1980's or even harsh 1970's, many of these same locations are equally deviant in March and now April.

What this coming week will mark however for the East-Half of the Nation is the transition from legitimate Winter-like cold & snows [i.e. Northern big City highs in 30's/40's] to what we call "mathematical cold" [i.e. significant negative anomalies but daily HDD totals generally < 20]. The bottom-line result is one of the coldest March/April periods for Eastern Hubs in modern history, but soon the full Winter coats and snow shovels can finally be put away.

Steeping back to look at the big picture, we remind you that this will translate to some substantial contrasts to 2008:

* A gradually milder Western U.S. for April 2009 versus April 2008.

* A markedly colder Northeast/Eastern U.S. for April 2009 versus April 2008.

* A significantly warmer May for most of Nation for May 2009 versus May 2008.

{i.e. longer Winter / shorter Spring / earlier Summer}

* Lower Western stream-flow (but much higher than projections from February) for May/June 2009 versus May/June 2008.

* Much fewer U.S. Tornadoes for first-half of 2009 versus first-half of 2008

Note: These aforementioned National temperature developments were pre-determined months ago and are not being driven by La Niña, El Niña, MJO, sunspots or volcanic ejecta.