Atlantic Tropical Action 2013

[phil882]

Is it just me or does the N GOM resemble a monsoonal trough? 

 

Fernand looks good, would have been a lot stronger if it didnt run into land so quickly

 

Well there is also 95E in the EPAC... Fernand is just part of the same wave axis. Part of the reason why Fernand is so small is due to the terrain influences that funnels cyclonic flow. Note that nearly every system that develops in the BOC is a small TC generally. If the terrain wasn't there, you would likely see a much larger cyclone with inflow originating from the East Pacific from 95E. 

[thewxmann]

It's official: TC's these days can only strengthen if they're <50 mi from the coast or in the subtropics.

[Snow_Miser]

Probably due to eastward progression of CCKWs, methinks.

 

I was thinking it had something to do with CCKWs and the MJO moving into more favorable octants.

[GaWx]

Garrett Bastardi complied some interesting statistics about cyclones in the BOC and significant Tropical Cyclones at landfall about 1-2 weeks later. The correlation is decent.. about 26/36 storms that were Category 2 or higher at landfall, East of 90 W over the last 50 years had a little system in the BOC/Western GOMEX 1-2 weeks beforehand. There are some notable storms with this correlation.

 

 1979 is the season to which I've been comparing the current situation because of the prediction of the strongest MJO phase 1 near the peak of the season since 1979. Well, it just so turns out that TD #10 formed on 8/25/1979 in the BOC. Mighty David caused major problems in parts of the Caribbean about 5-7 says later and hit the US as a cat. 2 ~10 days later. Actually, though, TD #10 and David formed on the same day.

[phil882]

This curious little guy has been going through convective pulses all day long.  Just crossing 50W now.

GOES0115201323841sfFE.jpg

 

It is an interesting little system, but its also stuck in the ITCZ and is likely too small to survive in the mean shear vorticity that dominates the ITCZ. There are some notable exceptions that have occurred in the EPAC but both the GFS and ECMWF just have this vort max fading off into obscurity in advance of the stronger and larger AEW entering the MDR. 

[jordanwx]

Garrett Bastardi complied some interesting statistics about cyclones in the BOC and significant Tropical Cyclones at landfall about 1-2 weeks later. The correlation is decent.. about 26/36 storms that were Category 2 or higher at landfall, East of 90 W over the last 50 years had a little system in the BOC/Western GOMEX 1-2 weeks beforehand. There are some notable storms with this correlation.

Garrett sounds just like his dad...relentlessly trying to establish causal relationships based off weak correlations. Remember, correlation =/= causation. The idea of the CCKW and/or MJO progressing eastward, as thewxmann mentioned, makes some sense but the idea that a small system in the BOC influences landfalling cat 2+s 1-2 weeks down the road makes no sense. Sorry Garrett.

[Amped]

There was a microcyclone in the BOC just before Katrina developed in 2005.

Bret Cindy Jose and Stan all formed there that year.

[icebreaker5221]

It is an interesting little system, but its also stuck in the ITCZ and is likely too small to survive in the mean shear vorticity that dominates the ITCZ. There are some notable exceptions that have occurred in the EPAC but both the GFS and ECMWF just have this vort max fading off into obscurity in advance of the stronger and larger AEW entering the MDR. 

 

Today's 12Z Euro appears to have analyzed the feature pretty well.  The Euro forecast has it much weaker by 12Z tomorrow and weaker still in 48 h.  I agree that the prospects aren't great, but it's looking just as healthy if not better than it did this morning.  It's definitely fragile tho, a very small increase in shear or just a little bit of that dry air wrapping in from the north and it will be gone in an instant. 

[GaWx]

Garrett sounds just like his dad...relentlessly trying to establish causal relationships based off weak correlations. Remember, correlation =/= causation. The idea of the CCKW and/or MJO progressing eastward, as thewxmann mentioned, makes some sense but the idea that a small system in the BOC influences landfalling cat 2+s 1-2 weeks down the road makes no sense. Sorry Garrett.

 

 If I'm understanding this correctly, I don't think Garrett was saying that the systems in the BOC actually influenced the later landfalling cat 2+'s. I think he is saying it is a "canary in a coal mine" because of the correlation he believes he found. Of course, correlation isn't the same thing as causation, but correlation, itself, can be an excellent forecasting tool if it is strong enough whether it be due to the eastward moving MJO or whatever. Does that make sense?

 

 Be that as it may, I have not studied this correlation, myself, and, therefore, have no opinion about how good a forecast tool this apparent correlation actually is. I just know about the 1979 case as of now because I just looked at it.

[jordanwx]

 If I'm understanding this correctly, I don't think Garrett was saying that the systems in the BOC actually influenced the later landfalling cat 2+'s. I think he is saying it is a "canary in a coal mine" because of the correlation he believes he found. Of course, correlation isn't the same thing as causation, but correlation, itself, can be an excellent forecasting tool if it is strong enough whether it be due to the eastward moving MJO or whatever. Does that make sense?

 

 Be that as it may, I have not studied this correlation, myself, and, therefore, have no opinion about how good a forecast tool this apparent correlation actually is. I just know about the 1979 case as of now because I just looked at it.

Idk what Garrett meant by the correlation exactly, I haven't seen his post myself. I guess I'm trying to remind everyone that correlation =/= causation, and Garrett's correlation is a great example. As you said though, a correlation in itself can be an excellent forecasting tool, provided the correlation is strong enough.

[Amped]

Looks like winds may have reversed in the area based on radar. That is one huge fire though. Hopefully it gets contained fast.

[TropicalAnalystwx13]

The 00z GFS is very similar to the 18z GFS and completely abandons the idea of the wave off Africa becoming a named storm, let alone a hurricane, before reaching the islands. I'm not seeing why...it seems to show the same upper-air pattern and overall environment as the 12z and the wave takes the same track. I was thinking maybe it was the lack of satellite data that I posted earlier, but that doesn't appear to be it. Maybe someone can help?

[phil882]

The 00z GFS is very similar to the 18z GFS and completely abandons the idea of the wave off Africa becoming a named storm, let alone a hurricane, before reaching the islands. I'm not seeing why...it seems to show the same upper-air pattern and overall environment as the 12z and the wave takes the same track. I was thinking maybe it was the lack of satellite data that I posted earlier, but that doesn't appear to be it. Maybe someone can help?

 

Perhaps because the wave isn't all the well organized currently. It shouldn't be too terribly surprising to see global models make rather large shifts in the perceived organization of a system 4-5 days in advanced when the system is poorly organized to begin with. If anything the GFS is taking a step towards the ECMWF which shows the system as a weaker entity as well.  

 

(thats not at all a bad thing, since the aforementioned 00z GFS takes the system into the Caribbean rather than on a potential recurving track). 

[Justin]

I really like the potential of some of these African waves to finally spit out a good system in the next seven to twelve days...fun times ahead i think.

[jordanwx]

The 00z GFS is very similar to the 18z GFS and completely abandons the idea of the wave off Africa becoming a named storm, let alone a hurricane, before reaching the islands. I'm not seeing why...it seems to show the same upper-air pattern and overall environment as the 12z and the wave takes the same track. I was thinking maybe it was the lack of satellite data that I posted earlier, but that doesn't appear to be it. Maybe someone can help?

Butterfly effect.

 

Ask that same question to a room full of people and you will probably get a variety of different responses, each pointing to some specific environmental condition. However, no individual environmental aspect is the problem, rather it's the sum of each part and how they interact. In other words, minor differences in the initial conditions result in major differences later down the road.

[HurricaneJosh]

You know it's been a bad couple of years when Josh is generous enough to say that a TS looks awesome.

 

Wave off of Africa up to 30% now for 5 days. 

 

 

Fernand looked good coming ashore.  The radar and MW imagery looked like a 'cane to me, and without other data, I would have guessed 65 kt or so.

[phil882]

 

Fernand looked good coming ashore.  The radar and MW imagery looked like a 'cane to me, and without other data, I would have guessed 65 kt or so.

 

I'd agree that Fernand was probably undergoing RI at landfall... although unfortunately without in-situ observations from recon, we won't know for sure what the actual max intensity was at landfall. Its too bad none of the Mexican radars are doppler, so therefore we can't make any assessment of the velocity from the reflectivity scans. 

 

PS: 00z ECMWF on the AEW is now has a Caribbean Cruiser like track... with the 850 hPa vorticity in the Central Caribbean (S of Jamaica) at 240 hours. Its still a pretty weak system at this time, but the 500 hPa vort max and 850 hPa vort max are aligned.

[HurricaneJosh]

I'd agree that Fernand was probably undergoing RI at landfall... although unfortunately without in-situ observations from recon, we won't know for sure what the actual max intensity was at landfall. Its too bad none of the Mexican radars are doppler, so therefore we can't make any assessment of the velocity from the reflectivity scans. 

 

Yep.  I know we always say this-- it's become a cliche on these boards-- but, man, another 12 hr over water and this thing would have gone to town.

 

By the way, it came ashore early-- wasn't supposed to happen until tomorrow.  Grrrr.

[Ed Lizard]

The Euro hasn't been stable at the end of its runs, but the latest 9 and 10 day forecast, something in the Caribbean and an apparent weakness developing that could pull something from the Caribbean into the Eastern Gulf/Florida, verbatim, that would be cool.

 

[dtk]

The 18z GFS completely dropped development of the wave depicted as a sub-980mb hurricane on previous runs over the past day. At a quick glance I don't see any reason why it would...perhaps the mets can help?

 

EDIT: Nevermind. Looks like the 18z GFS missed satellite data.

http://www.nco.ncep.noaa.gov/pmb/nwprod/realtime/gfs/t18z/index.summary.shtml

What data do you think was missed and for what cycle?  In terms of important satellite observations (AMSU-A, AIRS, ATMS, IASI, etc.), I cannot find any major glitches in any of the time series from our internal monitoring of actual assimilated data.

 

As an aside, the webpage you reference does not show what observations are used in the assimilation, they only show the "received/dumped" counts for everything that goes through the pipeline.  There are lots of observations that go through the feeds that we do not actually assimilation (lots of hirs, amsub, etc. on the older satellites, for example).

[am19psu]

Hey dtk, while you're here, do you have a quick link that can tell us if/when recon obs are assimilated? I know icebreaker (?) posted yesterday that HS3 obs were ingested, but I have no idea if they were again today. That would help a lot in knowing what happened between 0z yesterday and 0z today (e.g.). Thanks.

[bluewave]

That's one impressive area of dry air over the Tropical Atlantic. We really need a solid

tropical wave to come along that will survive the trip west. 

 

[Derecho!]

I don't pretend to  be an expert on model assimilation/initialization, but I always had a vague suspicion that sometimes a potential development would be shown based on a great Dakar sounding, but as the wave moved offshore and that last sounding became older and older, that a given model might "lose" the development down the road relying only on satellite data.

 

Anything remotely true about the above?

[Ed Lizard]

That's one impressive area of dry air over the Tropical Atlantic. We really need a solid

tropical wave to come along that will survive the trip west. 

 

wv-l.jpg

Its not horrible much South of 15ºN, and anything North of there that develops before about 50ºW is at increased risk for fishing.  Euro shows signs of life on several runs now, and last 2 runs of the FIM9 show a strong disturbance/possible TD or minimal TS crossing the Lesser Antilles with high heights to the North.  Specifics are hazy, but general trend is the wailing and grinding of teeth of August is a week or 10 days from improving.

 

 

Dr. Mike page also is more than glass half full...

 

 

 

 

 

 

[Srain]

The Multi Model Ensemble TC Genesis Probabilities suggest W of 50 will be the place to watch.

[wxmx]

 

Fernand looked good coming ashore.  The radar and MW imagery looked like a 'cane to me, and without other data, I would have guessed 65 kt or so.

The best looking cyclone so far this season, and it didn't even get it's own thread . Like you said, 12 hours more, 4mph translation less or 0.4 degrees latitude more and there would have been another story...ok, next.

[dtk]

Hey dtk, while you're here, do you have a quick link that can tell us if/when recon obs are assimilated? I know icebreaker (?) posted yesterday that HS3 obs were ingested, but I have no idea if they were again today. That would help a lot in knowing what happened between 0z yesterday and 0z today (e.g.). Thanks.

Adam,

Unfortunately, our conventional data monitoring leaves a lot to be desired.  However, it looks like we did not actively assimilate any of the drops on the 25th.  From our internal monitoring page (http://www.emc.ncep.noaa.gov/gmb/gdas/es_conv/copr/index_time.html), I can get a time series for data type 232 (u/v from drops):

 

Forget the difference between the red/black line, notice the big red spike in the bottom/4th figure....these are (counts of) observations that are set to be monitored (not actively assimilated) for some reason.  I have to ask around if this is by design or if there is an issue with the assignment of the observation subtype.  I suspect that these are getting a certain quality mark automatically assigned to them.  The 3rd graph shows the number rejected, and the spike on the 25th is also for some of the drops.  I did a little digging and these are all high altitude which are automatically set to be rejected. 

 

The first figure shows the counts for actively assimilated..I'll have to do some digging to see where the ~20 observations came from for 00z today.  I seem some big spikes recently for the 18z cycles, but haven't had time to do any digging.

[Ginx snewx]

http://noaahrd.wordpress.com/2013/08/26/contour-plots-of-tropical-storm-fernands-surface-wind-field-are-available-2/

[uofmiami]

I hope Dr. Ventrice shows up on here soon to give us the good news...

 

Dr. Jeff Masters:

He did yesterday:

 

http://www.americanwx.com/bb/index.php/topic/38601-atlantic-tropical-action-2013/page-55#entry2394059

[bluewave]

Its not horrible much South of 15ºN, and anything North of there that develops before about 50ºW is at increased risk for fishing.  Euro shows signs of life on several runs now, and last 2 runs of the FIM9 show a strong disturbance/possible TD or minimal TS crossing the Lesser Antilles with high heights to the North.  Specifics are hazy, but general trend is the wailing and grinding of teeth of August is a week or 10 days from improving.

 

 

Dr. Mike page also is more than glass half full...

 

 

 

 

 

 

 

You will know things are improving when you finally see a system take off once it moves poleward from the ITCZ

that you mention south of 15N. We still aren't there yet according to the 12z run of the Euro. But it seems to

be showing the potential for more Dorian or Erica type storms over the next week or so.