Good morning
This is from CROWNWEATHER this morning:
Tropical Weather Discussion, Saturday August 21, 2010 at 950 am EDT/850 am CDT
Issued: Saturday, August 21, 2010 950 am EDT/850 am CDT
For A Plethora Of Tropical Weather Information Including Maps, Images and Graphics, Go To:
http://www.crownweather.com/?page_id=29.
Discussion
Homebrew Development Possible Over The Next 5 to 7 Days:
We may need to really keep an eye on the waters off of the US Southeast Coast and in the northern Gulf of Mexico next week as there may be an opportunity for homegrown tropical cyclone development.
This opportunity appears to come around Tuesday and Wednesday as a frontal system tracks off of the US East Coast and part of the trough of low pressure associated with the front becomes cut off in an area stretching from near North Carolina southwestward into the northern Gulf of Mexico. This type of scenario is called a trough split where part of a low pressure trough becomes cutoff and drifts southwestward while the remaining part of the trough shears off to the northeast. It appears that this trough split could create a situation where a tropical system may develop in the northern Gulf of Mexico as early as Wednesday. The European model is the most aggressive with this possibility and forecasts a tropical cyclone to form just south of the Louisiana coast by Wednesday and forecasts it to track westward towards the Texas coast during the later part of next week.
As for the rest of the model guidance, the WRF model forecasts some sort of development in the northeast Gulf of Mexico starting late Sunday night or Monday morning. The GFS model doesn't forecast any type of development, although it does forecast a persistent area of low pressure to form in the Bay of Campeche for much of next week. The Canadian model forecasts something to form in the northeast Gulf of Mexico around Wednesday and forecasts it to track northeast up the US East Coast during late next week.
It should be noted that this same frontal system and trough will cause the development of a pretty robust nor'easter during the middle part of next week that causes strong winds and heavy rain to New England starting later Tuesday and continuing through Wednesday. This nor'easter will be in addition to a storm system that affects much of the Northeastern United States starting tomorrow and continuing into Monday.
So, while there is nothing threatening at the moment, it is something to keep an eye on over the next week or so.
Eastern Atlantic:
I am monitoring a pretty large area of disturbed weather, labeled Invest 95-L, located in the far eastern Atlantic. The reason this system is not organizing very fast is because it is dispersing its energy in too many areas at once and this slows the development process way down. I do still think Invest 95-L will develop, however, it is going to take its time.
The latest best track position from NHC puts Invest 95-L at 10.6 North Latitude and 31 West Longitude, however, there are a couple of areas of higher vorticity and convergence that are competing with each other for energy. The first area is near 11 North and 31 West, which is where the best track position from NHC puts Invest 95-L. The other area of higher vorticity and convergence is near 13 North Latitude and 24 West Longitude. I do think this will become a tropical depression in time, it will take longer than what was thought yesterday. My best guess right now is for this to become a tropical depression sometime on Monday.
Now for the possible future track of this system. The latest track model consensus is for a west-northwest track for the next 3 to 5 days and then pretty much all of the global models forecast that this system will curve out into the open Atlantic, although the European ensemble model forecasts a significant threat to Bermuda in about 10 days. Again, these are just model guidance forecasts and I am not taking them verbatim; that's why they call it guidance.
So, let's take a look at why the model guidance is forecasting what it is forecasting. They are forecasting that a weakness in the ridge of high pressure will develop in the central Atlantic in 7 to 9 days and pull this system northward. It is unknown right now if these model forecasts are correct, so obviously, I am going to be keeping an eye on Invest 95-L and the model trends surrounding it. As it is right now, the model guidance consensus is for a curve northward in about a week from now with a potential threat to Bermuda in 10 days.
So, let's throw out the model guidance for a minute here and take a look at a couple of benchmarks that I will be watching for: The first is whether it is moving almost due west when it crosses the 40 West Longitude line on Monday. If it is, then we will have to really evaluate the model guidance trends for possible threats down the road. The other benchmark I will be watching for is whether this system is north of 20 North Latitude before it reaches 60 West Longitude. If it is, then it is almost certain that it will curve northward into the open Atlantic. Also, generally the weaker this system stays in the short term, the further west it will travel as the steering winds in the low levels of the atmosphere are east to west right up through the Lesser Antilles. Now a much stronger storm would encounter a weakness in the east to west flow as it approaches 55 West Longitude that a weaker storm would not feel. One final thing to note is that we need a well defined center of circulation before we completely trust any of the model guidance. So, needless to say I am not sold on any final outcome for this system and I will be monitoring things very closely over the next few days. There is no immediate threat to anyone and there is plenty of time to watch things.
Finally, satellite imagery this morning shows that another pretty robust tropical wave was located over west-central Africa and will likely track into the far eastern Atlantic sometime on Sunday. The only model guidance that really develops it are the Canadian and to a lesser extent the European model. So, it is something to keep an eye on over the next few days.
The next tropical weather discussion will be issued sometime on Sunday morning.
Disclaimer: All forecasts herein are made to the best ability of the forecaster. However, due to standard forecasting error, these forecasts cannot be guaranteed. Any action or inaction taken by users of this forecast is the sole responsibility of that user.
