Good morning! I continue to watch the possibility of a subtropical storm developing off the Atlantic coast later this weekend and early next week. Remember, a subtropical storm is one that acts like a regular area of low pressure (cold-season low) aloft but, near the ground, acts more like a tropical area of low pressure. If a storm is deemed subtropical, it does take on a name; in this case, potentially Alex.
This is not a sure thing though! While the upper level support will be there in the form of a vast area of low pressure forming off the east coast, at the low levels, water temperatures are only marginally supportive of a warm core (tropical) system. A warm core system is one that develops independent of temperature gradients (or horizontal differences in temperature), it forms via convective processes (thunderstorm). In fact, while the developing low is now located near the Bahamas where the water is at or above 80 degrees, as the low moves to the north it will encounter cooler water. This will work against the formation of a subtropical storm. That said, most of our forecast models do indicate the potential for a subtropical storm to form, including the GFS model (included above). Notice the cooler water I've highlighted on the lower right panel -- the forecast for Tuesday morning -- and, perhaps more importantly, the belt of strong wind shear located just south of the low on the lower left panel. Bottom line is the atmosphere is marginally supportive of a subtropical system (NHC has acknowledged this by designating the system INVEST 90L, the first "invest system" of the season).
Regardless of what the outcome is with the classification of the storm off the east coast, our weather effects should be as outlined in my last blog post!
I'm also watching the potential for a tropical low pressure area to develop in the southern Caribbean by the middle of next week. If it develops far enough to the south, it will be in an environment very supportive of tropical development -- low wind shear and very warm/deep water. As it moves north though toward Cuba, Jamaica, and Haiti, it will encounter strong westerly wind and likely be shredded apart. It will be worth watching though and we'll do just that as we head into early next week!
Hope to see you at our hurricane expo tomorrow at the Charlotte Harbor Event Center. It will be your first chance to pick up the 2010 Hurricane Survival Guide and you'll get a chance to meet several WINK personalities! We have two seminars scheduled, one at 10:30am and the other at 1:30pm.
Brian
