Wednesday, July 21, 2010

Brian: Mainly dry weather continues for 2 more days...

Good morning! Hot and mainly dry weather continues through Thursday with strong high pressure anchored across the southeast. Underneath this high, the air is sinking -- both warming it up and drying it out as it sinks. In fact, it became so dry near the ground yesterday afternoon that the showers and storms that did develop had a lot of difficulty even putting a few raindrops on the ground. What happened? You may have noticed what looked like rain falling from the sky but evaporating before reaching the ground -- this is known as virga. What you also likely felt were strong gusts of wind; as these raindrops evaporated, the air cooled and quickly sank -- ultimately pushing rapidly outward in all directions. A similar set up is expected for today and tomorrow.
 
By Friday, the ridge of high pressure won't weaken so much as it will help steer a tropical wave in our general direction. Right now, I think many of our models are likely bringing this wave too far to the north (i.e. over the FL peninsula) given the strength of the high. This is still very much up for debate though as we won't have a solid idea until (and if) we get a defined center of circulation with this wave. That said, I still think we'll see an increase in our chance of rain as we move into Friday afternoon and Saturday as the wave crosses the Florida Straits and far south Florida. It is possible this system could be more organized as it approaches the area; upper level wind becomes more favorable for development near the Bahamas in about 36 hours. Right now, the tropical wave is feeling the effects of both some dry air and wind shear.
 
Brian

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