September 3rd Early Morning Thoughts as of 4 AM.
Lets look at a little history of Tropical Cyclone ERIKA. Originally all the models were showing ERIKA to take a sharp right curve. This sharp right curve was expected to take ERIKA out to sea and pose no threat to land. ERIKA was forecasted to move to the north of the Leeward Islands as well as NHC. History with ERIKA shows that this has not happened. Instead, ERIKA went across the islands and headed in a SW direction which was also not modeled to occur. So,once again ERIKA has defied the models and the pro mets. ERIKA has baffled the minds of many! Moving on to some of the more recent guidance...as recent as September 2nd..models were either dissipating ERIKA or they were taking her across PR...but more importantly they were taking her across Hispanola. Remember this point, we will come back to it.
Just as recently as yesterday evening..it appeared that there was a possible center relocation going on with the best convergence lying to the north of the islands. Convection was indeed blowing up in that location which made the most sense at the time due to where the best convergence was. As of the writing of this..the latest coordinates are not out. So we will wait to see whether that idea had any "sustained" merit or we could look at where the best convergence is as of 06 Z. So for the purpose of this discussion and my map I have used RECONS most recent center location of 16.6 N and 62.5 W.
This location actually makes the most sense when you look at where the greater covergence now is. This means that convection is blowing up over the center. So that convergence shifted south which means that the center more then likely is not going to relocate to the north. Now does this imply that ERIKA is going to move over Hispanola? Well before I attempt to answer that lets look at wind shear involved with ERIKA.
The first image is the current wind shear as of 0600. As one can see the wind shear has actually decreased around ERIKA. So her atmosphere is not quite as hostile as it was. The shear has been essentially been moving in tandem with ERIKA.
Looking at the mid level sheer it is only around 10 Knots. So generally conditions have improved somewhat for ERIKA.
Perhaps the most important aspect that has occurred in the early morning hours here with ERIKA is that she has actually begun to move off to the WNW. Its important for ERIKA to get out of the CARRIBEAN region as the combination of shear/substinance will more then likely cause ERIKA to dissipate.
Now, remember earlier that I said about the guidance from September 2nd...majority of models were either dissipating ERIKA and taking her across Hispanola? Well, most recent guidance is suggesting that a track to the north of the islands of Hispanola is now possible. This is important, not only does it show that the models have been essentially clueless with the system..but if that were to occur then the chances of ERIKA either maintaining minimal TS or maintaining TD status would go up as she takes her journey towards a better surrounding to the N of the Bahamas. Basically all "guidance" today shows this happening. The GFS/NAM/NoGAPs/GFDL/ most of the dynamical models/HWRF (to a lesser extent) all show this now occurring. The ECM keeps this as a weak open wave..well currently as of this writing ERIKA was still a tropical cyclone (TS) which already means that the ECM is in error. And not surprising as we are still 100+ hours out and not in its best time range. The GGEM appears to either take the system as an open wave towards the GOM or causes it to dissipate. So basically that puts the GGEM off on the wrong foot as well when it comes to comparing to the other recent guidance.
So what should happen here with ERIKA? ERIKA should maintain status of a tropical cyclone. There is the potential that she will be downgraded to a TD. However, as steering currents show she should continue to move off to the WNW with an increase in speed. This should take her close to if not over PR..but then skirt the island of Hispanola with her center of circulation remaining off shore. This will make any effect on the C.O.C minimal. Then as ERIKA moves WNW she should start to move off to the NW. With the synoptic setup of a huge CAR extended into the NE..I still do not think a trip up the east coast is likely...unless the NOGAPS idea..or HWRF idea were to occur. I think that once ERIKA were to get to the BAHAMAS ..conditions will become more favorable for potential intensifying back to TS if she loses that status by being downgraded. That is scenario #1 and the one that I think is the most likely to occur at this point and time.
Scenario #2 is dissipation as ERIKA would move to the west into a more hostile surrounding ..or move over the island of Hispanola and dissipate due to being a weak storm!
So in summary what to look for so theres no surprises.
1. Potential to be downgraded to a Depression.
2. Potential track to the North of Hispanola or over Hispanola depending on scenario outcome.
3. Potential to intenisfy down the road or dissipate (again dependant on #2)
With that all in mind here is my latest forecast track for ERIKA...
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