US Weather Commentary

Location: New York
Author: Weather 2000, Inc.
Date: Friday, August 31, 2007
 

While much attention has been given to ENSO status over the past 10 Years, it must be reminded that weekly SSTA fluctuations are mere “climate noise”, and it is rather the multi-month running mean of key ENSO monitoring regions which is of oceanographic and meteorological significance. Those unfamiliar with ENSO science and the strengths & weaknesses of ENSO models, advertised the most amplified projections only to back-peddle when weekly values didn’t suit their level of patience. The bottom-line is that the current ENSO status has been evolving precisely as it was supposed to withNINO 3.4 anomalies consecutively negative for the past two months, on its way to a moderate La Niña Event. These budding La Niña conditions helped spur a robust Southwest Monsoon over the past month, and merely the absence of El Niño will be conducive for the Atlantic Tropical Storm development in the months ahead. Despite the hocus-pocus of a posteriori “correlations”, La Niña did not dictate our U.S. Summer weather, but will be a significant force in our 2007-2008 Winter, driving Pacific Storm tracks into the Northwest, drying out the South, and unleashing Canadian-sourced volatility.

{Our neutral ENSO status at present is not at all surprising considering our multi-decadal research still monitors a strengthening of the Atlantic ThermoHaline Circulation occurring over several years now. These conveyor belt circulation patterns of the Atlantic Ocean, driven by temperature and salinity gradients, are enormously powerful mechanisms for shaping North American weather regimes for decades on end. Failure by other forecasters to understand, or account for, this process has led to the bungling of the last few Winters’ forecasts, and continual underestimation of Hemispheric Teleconnections. During the next two decades we believe (1.) El Niño Events will be muted & La Niña Events will be more numerous; (2.) Tele-Connection Phase Signs will support more harsh Winters in the East-Half U.S. [as we have seen the last four Winters]; and (3.) Atlantic Hurricane Seasons will be much more active and dangerous than usual. Consecutive Cold Seasons & routine Hurricane land threats [reminiscent of post-WW II into the 1970’s] is something we will again contend with as the “norm” for years to come.}

The 2007 Summer has thus lived up to our research expectations with all five key themes being achieved: (1) Excessive CDD tallies for the Mid-West to Mid-Atlantic Zone (Missouri to Del-Mar-Va); (2) Frequent drought-induced Heat-Spikes for the Southeastern States; (3) Anomalous Rainfall & Clouds with corresponding suppressed CDD’s/Critical Days for Texas and South-Central U.S.; (4) Robust Southwest Monsoon with a noticeable pull-back in temperatures mid-July through mid-August; (5) Routine Troughs and Cold Fronts for Pacific Northwest and into Northern Rockies.

Water was the red-flag variable in our research for the 2007 Summer, whether it was high/low soil-moisture levels, elevated dew points, or water vapor as fuel for clouds and rains. In the wettest of areas (New York had it’s 4th most Spring rainfall followed by its 4th most Summer rainfall), this expectantly translated into flooding events and damp/raw days imbedded within a warm muggy Summer Season (New York already has 20 percent more CDD’s than average and 21 Days > 90°F). In other areas water vapor was responsible oppressive Heat Indices which made 90°F feel like 100°F and 95°F feel like 110°F. And in the South-Central U.S. the latent heat of evaporation sapped the Sun’s energy away from warming the air (Dallas did not reach 100°F at all until August).

In a similar fashion to the Winter shifting further along in the Calendar that we’ve discussed in the past, we also advised that Summer Heat is becoming increasingly back-weighted toward the month of August, and even September (for the West). This can, and has starkly done so in 2007, leadto a crescendo of drought-induced or ridge-enabled heat waves, well after the days begin to get shorter. Heat, Drought and Forest/Wild/Brush Fires still need to be anticipated, especially across the Western States, for several more weeks before we can re-tune our sights on pending Winter patterns.

If the 2005 Atlantic Hurricane Season set an anticlimactic benchmark with a record-shattering 28 Named Storms, and if 2006 kept its historically-normal 10  Tropical Storms mostly out to Sea, then we must re-focus our attention on the bigger picture. The bottom line is 10 of the past 12 Seasons haveproduced more Storms than the long-term average (with only 1997 being below), and this trend is likely to continue during this active cycle of which we are in the midst. With Sea-Surface temperatures already at above-normal levels across the Caribbean and Atlantic basin, and the likely emergence of positive La Niña influences, odds are obviously skewed towards an active Hurricane Season in 2007. Hindering variables such as a surprisingly robust & persistent Saharan Air Layer (S.A.L.) and late-blooming El Niño influences, still allowed 10 Tropical Storms last year, so folks should not let their guard down (we have already experienced a rare Category 5 North American landfall). We will of course keep you abreast of the Season’s evolution, storm prospects, and our Hurricane intensity & path predictions, all via our Tropical commentaries and IM/Text alerts.

Our research findings are the opposite of the prevailing NOAA/NWS Climate outlooks and Others’ (i.e. continuous Western-Half warmth October-March), in that we believe there is support for anomalous cold across the West for the 2007 portion of the Winter, perhaps as early as October. A decadal climate pattern shift has made December-March sustained cold all but obsolete for almost the entire West (outside of localized pockets), but some of the Autumn patterns may carry-over this year (especially for the Rockies). On the other side of the coin, the East-Half of the Nation now has their Winter defined as January-March, with December being a potential onset month, and any November Cold essentially a fluke. The exception being downwind Great Lakes communities who will likely contend with a vigorous Lake-Effect Snow regime (October-December) due to warm lake temperatures & Canadian cold waves.

Hemispheric Tele-Connections will refine, enhance or locally counteract two main themes for the Nation this Winter: (1) Minimal precipitation and abundant sunshine for the Southern Tier States & Mexico; (2) Periodic intense Cold Waves (emanating from the Canadian Rockies and Northern Canada) with an Upper-Mid-West entry focal point, also establishing significant intra-month and intra-week volatility for much of the Nation. A warmer/sunnier Mexico and a colder Canada obviously sets the table for textbook thermal gradients, which is an ideal environment for cyclongenesis. Thus, Alberta Clipper and Nor’Easter Events should be more intense and commonplace (a la 1978-79, 1988-89 & 1995-96), as New York eyes its 5th Season of 40” of Snow in six years.

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