2000 EDT 17 AUGUST 2012
In my last update in the tropical section I went to some detail about how the pattern and set up in the MDR - the Main Development Rregion — of the Atlantic Basin was still set up quite favorably and was going to remain that way probably through the end of the month.
Since I made that update a few days ago things have clearly trended with continued above normal activity. The strong tropical wave which came off Africa last week– the feature which the operational GFS consistently blew up into a major East Coast hurricane– turned out to sea harmlessly earlier in this week. In doing so it showed that the GFS was off by about 2000 miles. In any event that system developed into a tropical storm GORDON a few days ago . The remains of tropical discretion #7 held together and regenerated in the bay of Campeche Sea yesterday and was upgraded to tropical storm HELENE this afternoon . Of course even though we are seeing above normal activity …none of this tropical activity so far has become a really big deal. After all it is a El Nino …. or at least so we are told but as you can tell from the overall weather patterns (the crippling heat / drought in the CONUS … the lack of rain in Southern Brazil in South America…. and in Australia… this is turning out to be a pretty abnormal El Nino event .
This first image shows us the current MJO impulse from the British European and GFS models. As you can see they all forecast the MJO to move steadily through phase 1 and 2 over the next 10 days. By the beginning of September the MJO might actually reach phase 3. As I stated several times over the past few weeks research clearly shows that there a much higher than normal probability of tropical cyclone development IF and ONLY IF… there is some sort of tropical feature which might develop. In other words MJO does not cause tropical cyclone development… It just enhances the likelihood that a feature might develop.
In addition the latest 200 Mb vertical velocity plots from CPC shows more extremely favorable conditions moving into the MDR. I have been talked about this development for few weeks and things are really looking favorable over the next 10 to 14 days. A particular importance is a cluster of strong rising motion in the atmosphere (lots of green) that is moving into the Gulf and the Caribbean over the next few days. Eventually this energy will move into the tropical Atlantic just as any potential system coming in from Africa heads towards the Caribbean or the Bahamas.
The problem is that we have a very strong system which is come off the southwest African Coast and the past 36 hours or so. You can see some the images here of this impressive system (94L)which is a large a massive tropical wave with a tremendous amount convection already in the system.
It’s also are fairly low latitude… And as you can see from the satellite image from CIMSS… the dust coming off of Northwest Africa appears to be fairly far to the north of the system. if so… then this tropical disturbance designated 94 L should not be impacted by the dust as so many systems so far this season have .
In addition as we can see the ward temperatures continue to warm nicely in the tropical eastern and central Atlantic… Which should also in the developer of the system.
The latest WIND SHEAR maps from CIMSS shows really like shear conditions across the entire tropical Atlantic especially south of 15N.
But decides the system being fairly far to the south the pattern is set up so that there will be large and powerful western Atlantic Ridge covering much of the central and Western Atlantic Ocean. This are ridge is known as the W.A.R. or western Atlantic rage that you may know of the more common name – ” the BERMUDA HIGH”.
This is very important because 94L is really far south and by staying at a fairly low latitude as it approaches the Northeast Caribbean ( 60 degrees west Longitude) the strong ridge or dome in the Western Atlantic Ocean get a chance to Build towards the USA East coast. In doing so the WAR will protect it from any sort of cold fronts or troughs that might come off the East Coast.
The European model has been particularly bullish on the system now for several days. Here is an image of the last three runs of the operational European … And as you can clearly see the trend is towards the Bahamas and wore the Southeast U.S. Coast at day 10.
Now keep in mind the European model is not showing the landfall here but the trend is towards the coast and that is what’s important given that this event is still 10 days out.
Here is a comparison of the 12Z Friday European operational and the European ensemble at 120 hrs / 5 days. As you can see we have a large huge dome in the Central Atlantic Ocean which will prevent this system from turning out to sea too early.
Next we have the day 10 European model also from 12z FRIDAY . What’s noticeable here is the remarkable agreement between the operational euro and the ensemble. The key as you can clearly see on the model is how strong the western flank of the Bermuda high ideas. This is always a critical aspect in forecasting any East Coast hurricane threat.
Indeed if we look at some the spaghetti diagrams of the European ensemble from m0z FRIDAY and 12z FRIDAY that you can get from STORMVISTA.COM (you really have to get an accoutn there… there model stuff is best there is) … We can also see this shift towards the Bahamas and the southeast coast at 204 hrs and to a lessor degree at 240 hrs.
And looking at the actual operational European model at day 10 we can see the tropical cyclone possibly intense major hurricane nearing the Bahamas off the floor to coast. We also see what appears to be a decent sized trough over the East Coast. Now it’s 10 days out so one has to wonder IF that trough is for real or …..is it being overdone by the model?? We also see a new heat dome developing over the lower planes and the southwestern states…. And if that heat dome builds and faster then the trough along the East Coast would be weaker and this in turn would increase the chances of the hurricane hitting the Southeast U.S. Coast.
As you can see there a lots of possibilities here.
what about the GFS Model? Quite frankly I don’t care with this model has to say about 94L and its development. There are several reasons for this. First let me remind you that the GFS model has a resolution problem after 192 hours which is day 8. If you don’t know what that means it refers to the GFS Model which has a different resolution after 192 hours out to 384 hrs ( day 16). This simply is not enough computing power over at HPC/ EMC to run the GFS model at the same resolution all way through to 384 / Day 16. As a result the model is famous for having these massive flip flops and inconsistencies AFTER 192 hrs. The European and Canadian models for example do not have this problem but the only one the model 2x a day. This is critically important when you are considering why the GFS model past day 8 does so poorly in figuring out the development and tracks of tropical systems.
SECOND as I mentioned earlier the GFS model did an absolutely atrocious job in forecasting the strong tropical wave from last week that came off the African Coast. If you recall the model developed into a major hurricane that threatened to hit the U.S. east coast around August 21-22. The system did not develop into a major hurricane and the GFS model was off by more than 2000 miles. Why would anybody give a rat’s an us about the GFS this far out in time.?
At this point you may ask … what about the vaunted European model… How did that model handle that system which later on became tropical storm GORDON? In fact the European took the system and turned it harmlessly out to sea in the Central Atlantic Ocean and then curve to back up towards the azores…. which is pretty darn close to what the GORDON has actually done.
Anyway if you really do want to take a look at the GFS models with regard to 94L… here they are. First we can take a look of the GFS model and see what it is doing differently on a large scale from the European model. It has the hurricane or tropical cyclone nearing the Leeward islands in the Northeast Caribbean as a pretty big system August 25 but be cause the model has a much weaker western Atlantic Ridge the GFS turns the tropical cyclone out to sea east of Puerto Rico.
Not surprisingly all since all of the hurricane models are based primarily off the GFS and the GFS grid it should not be a surprise that all of the hurricane models from this morning turned this tropical cyclone out to sea east of Puerto Rico. Monkey see Monkey do right ?
It turns out however that the 18z hurricane models have turn much closer to the European solution in showing a track much further to the southwest and implying a closer track towards the northeast Leeward islands.
SUMMARY: there appears to be a high probability of a significant tropical cyclone in the cape verde hurricane pipeline coming down which could be develop into a category 3+ hurricane at some point in its lifecycle over the next 10 or 12 days. In general ….looking at the overall pattern AT THIS TIME…. it does not appear to be what I would call favorable for East Coast hurricane strike and if I had to make a bet right now I would favor a near miss with the tropical cyclone passing between Bermuda and the East Coast. But there are still a ton of possibilities out there and a ton of variables. I do believe that this is NOT going to turn out to sea EARLY and that the dust will not affect it and it has a high potential to become a significant hurricane. There are several additional benchmarks to watch…. For example if this TC ere to pass through the Northeast Caribbean / Leewards islands … THAT would greatly increase the chance of a U.S. landfall. Likewise if this system were to pass close to the Bahamas THAT also would increase the chances of the U.S. landfall.
And lastly I have notice the date of possible close passage to the East coast which should be around August 28 or 29 …. one year ago to the day that Irene came into Eastern Virginia and Eastern North Carolina.