US Weather Commentary

When we mentioned cold and snowy weather returning to the Northern & Eastern States ahead of the St. Patrick's Day Weekend, we meant cold and snowy.  After a pleasant respite from the harshness of the 2007 Winter, with balmy temperatures expanding over most of the Nation this week, the next Polar wave is diving down from Canada, right on schedule.  Our concerns voiced last week for anomalous cold, windchills and snow/sleet accumulations for portions of the Northeast quadrant, are slowly being realized by computer models and other forecasts (which have finally adjusted a good 10-15°F colder across major Mid-West and Northeast cities for Friday & Saturday).  The weather will swing back in a Spring-like direction for Nation next week (especially for Central U.S.), but Northern & Eastern States still remain vulnerable to occasional Winter-like episodes wrought by the NAO/AO/PNA, through mid-April.

"Fast & Furious" March igniting Floods & Fires at record clip

March 2007 has impressively been producing both anomalously large Heating Degree Day tallies simultaneously with anomalously large Cooling Degree Day tallies (in the deep South), so when those air masses clash, sparks fly, and the result is over 190 U.S. tornadoes in 2007 to-date (well ahead of the average we're supposed to have even through April 1st).  In other cases the severe weather takes the form of concentrated downpours & flash-flooding events (as we are witnessing across the Western Gulf Coast region. But this often does not translate into widespread saturating rainfall (or the ground can not absorb downpours that fast), and as a consequence, drought continues to evolve over several States across the Southeast and South.  Across the Southwest, 90°F temperatures are the result of subsidence and compressional warming, which only further dry out the air column and fuel the forest/brush/wild fires.

Summer 2007 Forecast Requests:

On Wednesday March 14th, we commenced accepting requests for our site-specific predictions covering all or portions of the 2007 Summer Season.  From cumulative Cooling/Growing Degree Days, Extreme temperature occurrences, Precipitation, or multi-variable scenarios, we outlined examples and case-studies for you by e-mail.

2007 Hurricane Season Outlooks:

On Wednesday March 21st, we will issue qualitative outlooks, insights, commentaries and general advisories for the 2007 Atlantic Hurricane Season.  With Hurricane #1 (in 1908) having reached 100 mph...in March...it is never to early to get your tropical ducks in a row.

REGIONAL WEATHER BRIEFS:

NORTHEAST:

The best motto for the current week will be "Seventies-to-Snow", as Newark AP set a daily record of 79°F yesterday only to have the NYC Tri-State region facing a substantial Snow & Sleet Nor'Easter event tomorrow, with cold & blustery conditions through the St. Patrick's Day Weekend.  While southerly winds typically bring milder air for most areas, keep in mind that [Atlantic] Ocean temperatures are at one of their coldest levels in mid-March, so coastal communities could still remain quite cool when such advection is occurring.  Such tumultuous intra-month weather swings will continue to characterize March 2007, with Boston illustrating this quite clearly: 57°F on March 3rd, 3 days never above 26°F from the 6th-8th, likely 60°F tomorrow, and back to only 30's for a high over the weekend!

SOUTHEAST:

Mostly sunny skies and some recently anomalously warm weather, will soon be replaced by cloudier, stormier and more Seasonable temperatures.  At this point the Southeast U.S. is becoming largely immune from Polar air masses that may swing through further North, but cloud-cover can definitely place a lid on afternoon temperatures.  Despite any storms, evolving drought across multiple States needs to be monitored with extra vigilance in the weeks ahead.

NORTH-CENTRAL:

Coming in at a close 2nd place behind the Northeast for volatile temperature swings this March, the recent thaw across the Upper-Mississippi Valley & Great Lakes has been abruptly ended by another round of Polar air, wind and frozen precipitation ahead of the St. Patrick's Day Weekend. Quantitatively, this will be demonstrated as Chicago dives from mid-70's to upper-30's. Towards the High/Northern/Western Plains, temperatures will ebb and flow from extreme positive anomalies to slightly mild weather, but they have pretty much wrapped-up the final vestiges of Winter cold they will be contending with this year, as they set their sights towards Spring.  {On February 21st 1918, Grandville ND sky-rocketed from -33°F to 50°F in less than 24-hours(!), so folks in these parts understand the power of subsidence and Chinook winds at the end of the Winter Season}. 

SOUTH-CENTRAL:

As we move through March, this region of the Nation starts to become increasingly reliant on strong solar radiation to boost temperatures to above normal levels, and logically the sunnier days will generally be the warmest, and the cloudier/rainier days will be the coolest.  Thanks to some intense Mesoscale Convective Complexes (MCC's), there is an emerging divide between wetter weather across Eastern Texas and the Western Gulf Coast States versus the increasingly dry Northern/Western Texas and Southern Plains. Our longer-term assessments continue to point in the slightly warmer direction for the entire region, but the larger anomalies will likely come from the down-sloping areas closer to the Rockies Foothills.

NORTHWEST:

A cloudier but warmer pattern for inland sections and a wetter and cooler pattern for coastal sections continues on, as the vast majority of Northwest-focused precipitation in contracting further  (now mostly concentrated within 75 miles of the Pacific shoreline).  While this adds an exclamation point to the cumulative precipitation tallied by Seattle since October 1st, it does little to help inland/mountain hydro-electric areas across Oregon, Idaho and Northern California/Sierras which will likely portend to a Spring stream-flow only 50-90% of Normal.

SOUTHWEST:

Probably the most consistently dry & balmy weather across the entire U.S. over the past week and days ahead, unusual Cooling Degree Days have even been tallied this past week with Riverside and USC campus hitting 93°F, San Diego and LAX hitting 86°F and even San Francisco setting a daily record at 77°F.  Some of the more extreme Santa-Ana induced heat is already moderating, but the Warm-Dry-Warm-Dry positive feedback cycle looks to have a tight grip on the entire region as we head into Spring.  Unfortunately, this is also exacerbating drought and wildfire risk across the region, joining their South-Central and Southeast neighbors in this mostly sunny and dry patterns (but minus the severe weather).

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