US Weather Commentary

Location: New York
Author: Weather 2000, Inc.
Date: Wednesday, August 29, 2007
 

Tropics and Weather Comments

Remember, we have about 24-36 hours remaining in our current "favorable phase" in the Atlantic before the next lull sets in, so we continue to monitor the still-disorganized Eastern Atlantic Wave.  Over the past 4 weeks, 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 believe it is essential to 'pencil & paper' analyze the underlying fluid-dynamics and thermodynamics regardless of what this model or that model says (which have > 90 percent False Alarm Rates).

You have enough clutter in your life than to worry that a "tropical wave dropped one mb in pressure!", or "two more thunderstorms popped up in the Bay of Campeche!", or "the American Model produces a Hurricane in the Caribbean in 15 Days!". {Calling a Hurricane in the Atlantic Basin in a La Niña September is going out on a limb as much as calling a Michigan snowstorm in January).  You'll hear from us first when a legitimate tropical entity is imminently about to be classified, AND before an official classification hits public weather & news wires.

Historic East-Half August Heat wrapping up along with Calendar........

  • St. Louis reached between 95°F - 102°F for 11 consecutive days, and 95°F - 105°F on six days thereafter.
  • Memphis has reached 95°F every day this month, breaking 100°F on 13 occasions!
  • Cincinnati is incredibly having an August, three standard deviations hotter than normal!
  • Baltimore had six days of 95°F or greater, the most days since August 2002.
  • Fayetteville NC, spurred on by drought, has already broken 98°F on 14 days this month, including four days at least 104°F
  • Atlanta tied their record for most 100°F days in a Summer with nine.

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 four 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.

Big changes in store for West by September.......

Whether it has been ongoing muted Summer patterns (like the robust Sea Breeze suppressing the L.A. basin), or cooler patterns of the past four 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.

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