US Weather Commentary

Location: New York
Author: RiskCenter Staff
Date: Tuesday, August 28, 2007
 

Portions of Northeast experienced hottest day of Summer on Saturday.....

With New England stations such as Boston MA [96°F] and Concord NH [97°F] soaring to their hottest temperatures yet this Summer on August 25 coupled with 100°F+ Heat Indices from Florida to Maine, it further demonstrates that August is in fact the new July, and we still need to keep our eyes pealed for some final spikes of the Season.

Once we turn the calendar to September, the diminishing daylight hours makes it very difficult for Upper Mid-West and Northeastern States to produce critical days unless extreme conditions are present (i.e. severe drought & strong ridging pushed Chicago to a record-late 4 days in a row over 90°F the week after Labor Day in 2005).

However, the diminution of Critical Days does not mean Northern States East of the Plains can not enjoy pleasantly warm Summery temperatures.  In fact our research has pointed to some weeks of ample warmth in September 2007 for the Great Lakes, Ohio Valley, Mid-Atlantic and New England. Consequently, we imagine that NWS 6-10 and 8-14 Day outlooks would have to make some revisions today (removal of below and/or addition of above contours) contrasted to their outlooks over the weekend, across the aforementioned regions.

Whether it has been ongoing muted Summer patterns (like the robust Sea Breeze suppressing the L.A. basin), or cooler patterns of the past 4 weeks (such as frequent troughs & fronts across the Northwest, and Monsoonal clouds & moisture across the Southwest), big changes are in store for many Western regions as we approach and enter September 2007.

The Northwestern U.S. will have mean-troughing replaced by mean-ridging over the next week and for September, spurring them on to their most anomalously warm temperatures since July, with critical days possible fueled by underlying moderate to severe drought.

The Southwestern U.S. 2007 Monsoon patterns (clouds, moisture, rains) are coming to a close, and will be replaced by subsidence, and ample desert sun, resuming the hot temperatures reminiscent of this June and early July.

Coastal California, under the grip of one of the most powerfully consistent Sea Breeze regimes this decade, should experience a lot more off-shore flow during September, which would enable Santa Ana temperature spikes, and likely their hottest month yet of the Summer Season.

Sierra Nevadas/Interior West/Rockies were immune and isolated from the other regional August pull-backs, and thus will continue on with the warm patterns they have witnessed rather consistently this Summer.  Eastern portions (such as Colorado and New Mexico) will be that much closer to the cooler and stormier Plains, so they may actually take a step back from their August warmth.

Favorable phases of various atmospheric & oceanographic oscillations helped produce CHANTAL followed by a lull, and then DEAN & ERIN followed by a lull.  Stationary Fronts or the tails of Surface Troughs near North America can spur tropical cyclone development at any time, but we will probably have a lull into the first week of September unless something gets going in the Caribbean or off of Africa within the next 48 hours.

  • For your reference, the next 2 classified Tropical Storms will have the names FELIX and GABRIELLE.
  • The average date we witness our 2nd Named Storm of the Season is August 6. {We reached this mark on June 1st this year}.
  • The average date we witness our 3rd Named Storm is August 20 {We reached this mark on July 31st this year}.
  • 91 percent of all Major Hurricanes in the GOM have taken place between August thru October
  • Every Category 5 Hurricane in the GOM, in history, occurred after August 1

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