Current thoughts on Tropical Storm Erika, as of 3 PM EST on September 2nd. Its not a surprise that ERIKA is currently located at 16.2 N and 61.1 west. It is also not a surprise that ERIKA is weakening at this point and time. ERIKA has been fighting off to the best of her abilities the dry air in her surroundings. At times it gets the better of her and she weakens. However...when diurnal max comes around she strengthens back up. Currently she is close to the islands. This is important to remember. Close land interaction can also be responsible for the weakening that we are seeing at this time with ERIKA.
12 Z guidance from the ECM to the GFS.(basically dissipates) .to the NAM, including the GGEM all dissipate this system. On the other side of the spectrum, the GFDL/HWRF maintain the systems strength (some weakening evident on the GFDL) and then restrengthen ERIKA. Meanwhile the NOGAPS from 12 shows quite the potent system riding up the eastern seaboard.
First lets look at what is currently happening to ERIKA. Lets look at the shear.
This will update shortly for the 18 Z, however since this is currently the only available it will reference whats happening. To the NW side and to the southeast side of ERIKA there is 20 to 30 knots of shear. However, i do not think the shear is as much an issue ,as ERIKA has been dealing with dry air. The slowing down of the system also could be a component of the weakening. So right now ERIKA is a minimal TS..perhaps bordering on a depression..which i mentioned was a possibility of happening at around 5 Am and i still will stick with that potential happening.
Now lets turn to the steering currents. Again, they are pretty much showing that a west to west northwest track should continue. A weaker system will be subjected to follow the lower level steering currents.
I think its important not to pay to much attention to the tracks that the models are currently showing. Rather, I think its more important to pay attention to the synoptic setup that is going to be in place. Sometimes a forecaster will have to put the models aside and focus more on the synoptic setup. Lets think back to several days ago. What were the models showing at that time? The models from the global to the dynamical to the hurricane models were all showing a sharp right turn or a recurve. How close were they to being correct? What model actually showed the southern extent of this system where it currently is? The models have been trying to play catchup to ERIKA, as ERIKA has been defying all the models and basically the professional mets thoughts. Its very important at this point and time when following ERIKA to pay more attention to satellite and steering currents and synoptic patterns and teleconnections.
So what does the synoptic pattern look like? All guidance and I emphasize the word guidance, is suggesting that there is going to be a strong central atlantic ridge attached to a ridge of high pressure over the Northeast. The guidance has suggested that the weakness that was origininally being showed was nothing more then convective feedback. With such a ridge in place a weaker system is going to have a hard time penetrating that type of ridge in place. So where does ERIKA go?
The two scenarios that I am looking at right now are below.
Scenario # 1. Erika continues to maintain her strength at either a TD or minimal TS and heads W and then WNW towards Florida. Once north of the Bahamas...extremely warm waters could potentially cause ERIKA to reintensify. Potentially putting FL in the bullseye! I do not see this making a trek up the east coast, UNLESS, the intensification process is like the NOGAPS, and at that point ERIKA would be able to just plow thru that ridging. At this time, i think that is too extreme.
Scenario #2 is that ERIKA keeps moving off to the West and enters the Carribean. If this were to happen ERIKA could potentially dissipate.
These are the only two scenarios that I can see happening at this point and time and i would suggest that both scenarios are indeed possible. For now, the map above is what i am sticking with. Stay tuned for further updates.
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