Charles E. Roop giving his own forecasts, weather discussions, photos and adventures for the Starkville, MS area, Florida, and beyond.

Wednesday, July 21, 2010

Invest 97L Not So Tough

Since last night, the tropical disturbance that is now located over the southeastern Bahamas has deteriorated a bit. It seems that wind shear from the nearby upper-level low, dry air intrusion, and the center of circulation moving over Hispaniola has affected this disturbance.

Earlier this afternoon, a NOAA G-IV jet inspected the region. Data indicated that upper-level winds are still not favorable for development, according to the National Hurricane Center. Sounding data also showed dry air at the mid levels to the west and north of the system.

A look at infrared and water vapor loops show convection starting to get a little better, but the water vapor clearly shows the upper low to the north.

The NHC thinks that upper-level winds will be "marginally favorable" for development in the next day or two. NAM and GFS models show the upper low moving ahead of 97L in time, but would it move far enough to reduce interfering the wave? Not sure.

The NHC has reduced its probability of reaching tropical cyclone criteria to 40 percent. It seems reasonable given how much of a hill this invest has to climb to make it to a depression, or even a storm.

The NAM, GFS, and other models seem to agree on a south Florida initial impact as early as Friday.


- At this time, it appears that it will mostly be an on-and-off rain event for south Florida. There could be some gusty winds, but nothing to freak out about.

- Rain should start to kick in sometime Friday and last through Saturday...maybe longer as a southerly flow should keep moisture levels high.


- NWS-JAX is calling for a 50 percent chance of rain for Friday and Saturday. The further north you go, the lower the rain chances. However, this would depend on how far north the tropical wave moves, or how strong it gets.

As time moves forward, it seems this thing might be nothing but a fizzle. Still, it is worth watching. This might be my last update on Invest 97L unless conditions change.

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