Midday/Tropical Update

There is a low chance of thunderstorms tonight in advance of a cold front moving across the Great Lakes region.  The front will be beneficial however, as dewpoints in southern New England are currently running in the mid 60's.  Behind the front in Michigan dew points in some areas are in the 40's.  This is very comfortable air and it will stick around for a couple of days.  Canadian air in summer feels great after days and days of dew points in the upper 60's and low 70's, which is what we have been experiencing.  Besides the slight thunderstorm threat tonight the forecast for tomorrow, Friday, and Saturday is pretty straightforward.  As meteorologist Justin Perry says the borecast is sunny and 80 for the next 3 days.  Actually Saturday may be quite warm as high pressure moves offshore and the winds will turn to the southwest.  Highs in the upper 80's are possible.  The run ends Sunday when showers return and possibly a repeat of this past Sunday with heavy rain.

Tropics Discussion

Interesting things are beginning to happen in the Atlantic Ocean.  Two well developed tropical waves have emerged off of Africa and I think both will develop.  The first wave is large and has plenty of its own moisture; therefore the dry air and Saharan dust will have a minimal impact on the system.  So if this storm develops, which several models (including the special tropical cyclone only models) are indicating, its name will be Franklin.  The wave behind it, also is forecast to develop, would be named Gert.  A third wave behind this one, if it were to develop, would be named Harvey.

When a series of tropical waves develop like this, they each play a role in the track of the others.  Consider the "I" formation and a "41" quick sweep.  The guard pulls, which would be the first wave, or Franklin and leads the way.  This storm would put moisture in the air for the second wave (possibly Gert).  Gert is the fullback and the second wave in a series like this tends to move further west (see Earl 2010, Fran 1996).  In this scenario, the first wave (if it were to develop) is still one to watch because Edouard in 1996 prompted Hurricane Watches and warnings for the East Coast before ultimately moving out to sea.  The final wave in the series usually is left in cooler waters due to the upwelling of cooler ocean water caused by the first two storms. The tailback gains several yards before being brought down by the "defender" (the upwelled water).  However Atlantic ocean temperatures are among the warmest recorded in history, slightly behind 2005 which was the most active season on record so how much of a factor this is remains to be seen.

2011 sea surface temperature anomaly charts (NOAA)

Long-time Hurricane researcher Joe Bastardi posted on his twitter that the overall trend is looking like 1955 and 1999, both analogs to this hurricane season.  Both times multiple hurricanes approached North Carolina.  Certainly things are looking ominous in the long range, but it is long range so nothing to panic about, just something to think about.  I don't like to over hype things or cry wolf as I've been humbled by snowfall forecasting several times.  Just given the tough economic times that the world faces, if a threat exists people should know about it.


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