Saturday, August 4, 2012

Tropical Storm Ernesto!!

This Tropical Tidbit is from Levi Cowan!! His material will be posted here when i cannot personally post updates!! I trust his forecasts and analysis!!

Ernesto has become better organized since yesterday with a persistent CDO and expansion of the spiral bands and upper-level outflow. However, recon this morning found that Ernesto has not strengthened since yesterday, and the central pressure is actually up a few millibars. The impressive organization of Ernesto with this high of a pressure came as a surprise to me, but the idea that this storm would halt intensification upon entering the Caribbean until about 75W has verified nicely so far. I explain in the video my theory as to why Ernesto has been firing all of this convection without strengthening.
Once past 75W, or about the longitude of Jamaica, conditions will rapidly improve for Ernesto as the upper-level pattern allows expansion of upper ridging above the storm, and the trade winds slow down in the western Caribbean, both of which should allow pressures to fall and the storm to strengthen. We could see Ernesto quickly become a hurricane in the western Caribbean, and a big problem for the Yucatan Peninsula. If Ernesto crosses a portion of the Yucatan it will knock it down, but Ernesto may reach his peak intensity afterwards in the Gulf of Mexico.
Ernesto’s track is still the toughest part of this forecast. It will largely be a function of his intensity, since a stronger storm will tend to move more northward into the weakness in the steering ridge that will be over the north gulf coast over the next several days. The forecasted pattern consists of not a wide open trough, but rather a large area of sprawling, light, erratic winds over the Gulf of Mexico, indicative of a weak steering pattern that a strengthening Ernesto will likely start to turn more northwest into while moving slower. I believe this will eventually take Ernesto near the northeastern Yucatan, and then into the western Gulf of Mexico. The largely uncertain part of the forecast is where the second landfall in the Gulf of Mexico will be. Right now I am leaning towards the idea that Ernesto will be guided back towards the WNW by the Texas ridge into northern Mexico or southern Texas, a solution supported by last night’s ECMWF ensembles. However, this is still 6-8 days out, and if we have a particularly powerful hurricane moving far enough north in the NW Caribbean, the door could open for a track into the north gulf coast instead, so the entire north and west gulf coasts and the Yucatan Peninsula should closely monitor Ernesto, as he could become a big problem down the road.
We shall see what happens!

Tuesday, July 31, 2012

Tropics Heating Up: Invest 99L

Good Evening,
 Despite a rather dull July in the tropics, things are starting to heat up and become more active. Yesterday an area of low pressure was designated Invest 99L by the National Hurricane Center. This area currently has a 50% chance of developing into a tropical cyclone within the next 48 hours. Also entering the northeast Carribean sea is a vigorous tropical wave. While this wave is not currently expected to develop in the short term, it may have to be watched should it enter the GOM where conditions in 4 to 5 days could be more favorable.

Forecast for Invest 99L
99L is currently embedded within the ITCZ or Intertropical Convergence Zone. Before significant development can occur 99L must lift itself west-northwest and detach from the ITCZ. Conditions are fairly conducive for development as 99L approaches the Lesser Antilles islands this weekend. Most operational model guidance bring 99L to tropical storm status before entering the Carribean Sea. Once in the Carribean wind shear could be a limiting factor to the intensification of 99L due to a weak El Nino. During El Nino years trade winds are typically stronger in the Carribean limiting development of tropical systems. Once in the Carribean the TCHP or tropical cyclone heat potential will come into play in strengthening 99L. The TCHP is the amount of deep hot water available to fuel a tropical cyclone. A recon flight is tentatively scheduled for Friday, August 3. If recon can find a closed area of low pressure the models should be able to get a better handle on where 99L will eventually track.