Tropical Update (8/18/2011)

Now that I have a little bit of time, I can update you on what is going on, as far as the tropics are concerned.

Invest 93

Invest 93 has become much more organized since my last post, however, it is still considered a tropical wave.  Its movement, currently, is westward at around 10-15 mph.  The potential for strengthening is there, but a recon plane flew into the storm and found 20F dew point temperatures about 1000 ft above sea level. This dry air has kept it from organizing into a tropical cyclone thus far, and there is still questions on how this dry air will affect it over the next 24-48 hours.  Right now, NHC has it at a 70% chance of it becoming a tropical cyclone within the next 24-48 hours.  Although this is very possible, I am still skeptical to this statement.  The recon plane didn’t even observe a well defined low level circulation in the storm, however, this may change in the upcoming hours.  It looks like it will stick with a westward track, but some models have it turning to more of a west-southwesterly direction by Friday evening.  Either way, contact with land will weaken any strengthening it does between now and then.  Though the Rio Grande Valley will not see a significant amount of rain from this, any northerly track will increase moisture from the south and southeast and will begin making its way to the area by as early as Sunday.  This perhaps will give us a shot at some showers and thunderstorms by late weekend/early week, figures crossed.

Figure 1. 06 UTC 8/18/2011 Spaghetti plot of Invest 93.

Tropical Wave (Invest 97)

Concerns for another tropical wave out in the middle of the Atlantic has my attention right now.  NHC currently has a 10% chance of it becoming a tropical cyclone within the next 24-48 hours.  This wave needs to be monitored closely for the next 3-5 days because I believe this wave has potential to not only become this year’s first Atlantic hurricane, but the first hurricane to strike the U.S. since Hurricane Ike in 2008.  It is still way too soon to determine how strong this wave could be in the next 5-10 days, but warm waters, as well as low wind shear are favorable for further development after 48 hours.  The only problem it would have developing would be contact with land and maybe some dry air.  Contact with the Lesser Antilles, Puerto Rico, and Dominican Republic are all possible with this wave in the next 5-7 days.  Let’s hope that making landfall with these landmasses will hinder its development into a hurricane.  The reason why this wave concerns me so much is because ECMWF, DGEX, and GFS have a hurricane developing out of this tropical wave and striking the southeastern United States in about week and a half.  Yes, models tend to be inaccurate when forecasting that far out, but when two or three models start agreeing early, it’s not a good sign.  I will continue monitoring this system myself.

Figure 2. 2 a.m. EDT NHC probabilities (%) of tropical cyclone formation in the next 24-48 hours.

Figure 3. 745 UTC 8/18/2011 IR satellite image of Atlantic Basin. Click on image to zoom.

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About Brian

University of Oklahoma graduate with a degree in Meteorology. Follow me on Twitter: @WeatherInformer
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