Atlantic Tropical Action 2013

[TropicalAnalystwx13]

^ No.

"Historically, there have been eight significant positive IOD events since reliable global

OLR data became available in 1979. While these

events have occurred during all phases of ENSO,

they are typically associated with reduced Atlantic

hurricane activity (Fig. 16b). The positive IOD

event in 2011may have been one reason why the

overall Atlantic activity was lower (i.e., at the low

end of the NOAA seasonal Outlook issued in

August) than what might have been expected given

the combination of conducive climate factors

described above.

SST Anomaly: September-November 2011

SST Anomaly in Nino 3.4 Region (Black Box Above)

a

b

Fig. 15. (a) Sep.-Nov. 2011 sea surface temperature (SST)

anomalies (°C). ( Time series of monthly area-averaged

SST anomalies in the Niño 3.4 region [black box in (a)], with

red line indicating the threshold for a La Niña. Anomalies

are departures from the ERSST-V3b (Smith et al. 2008) 1981-

2010 period monthly means.10

The observations suggest that the IOD

may have acted to limit the 2011 Atlantic hurricane

activity by weakening both the west African

monsoon circulation and the La Niña-related

convection patterns. There are three indications of

a weaker west African monsoon system compared

to the 1995-2010 mean. First, the anomalous

upper-level divergent circulation over northern

Africa was weaker and less focused, and the

anomalies were actually less than those over the

western equatorial Indian Ocean (Fig. 12a).

Second, the position of the 200-hPa

subtropical ridge axis over the eastern MDR was

located approximately 10o

 latitude farther south

than the 1995-2010 mean (red lines, Fig. 9a). A

similar southward shift of the ridge axis was seen

during the 2007 Atlantic hurricane season, which

also featured a strong positive IOD (Bell et al.

2008). Third, the anomalous southerly flow in the

lower atmosphere was confined to the southern

MDR and Gulf of Guinea region, rather than

extending well into the central MDR and the

African Sahel region (Fig. 8a).

The positive IOD also appears to have

affected the La Niña-related convection patterns.

One component of La Niña is an extensive area of

enhanced convection across Indonesia and the

eastern Indian Ocean. However, convection was

suppressed over the eastern Indian Ocean during

ASO 2011 in association with the positive IOD

(Fig. 11), meaning that the La Niña forcing of the

atmospheric circulation was weaker than if no

IOD signal had been present. A similar observation was made by Bell et al. (2008) for the 2007

Atlantic hurricane season."

 

http://www.cpc.ncep.noaa.gov/products/expert_assessment/hurrsummary_2011.pdf

[bluewave]

 

^ No.

"Historically, there have been eight significant positive IOD events since reliable global

OLR data became available in 1979. While these

events have occurred during all phases of ENSO,

they are typically associated with reduced Atlantic

hurricane activity (Fig. 16b). The positive IOD

event in 2011may have been one reason why the

overall Atlantic activity was lower (i.e., at the low

end of the NOAA seasonal Outlook issued in

August) than what might have been expected given

the combination of conducive climate factors

described above.

SST Anomaly: September-November 2011

SST Anomaly in Nino 3.4 Region (Black Box Above)

a

b

Fig. 15. (a) Sep.-Nov. 2011 sea surface temperature (SST)

anomalies (°C). ( Time series of monthly area-averaged

SST anomalies in the Niño 3.4 region [black box in (a)], with

red line indicating the threshold for a La Niña. Anomalies

are departures from the ERSST-V3b (Smith et al. 2008) 1981-

2010 period monthly means.10

The observations suggest that the IOD

may have acted to limit the 2011 Atlantic hurricane

activity by weakening both the west African

monsoon circulation and the La Niña-related

convection patterns. There are three indications of

a weaker west African monsoon system compared

to the 1995-2010 mean. First, the anomalous

upper-level divergent circulation over northern

Africa was weaker and less focused, and the

anomalies were actually less than those over the

western equatorial Indian Ocean (Fig. 12a).

Second, the position of the 200-hPa

subtropical ridge axis over the eastern MDR was

located approximately 10o

 latitude farther south

than the 1995-2010 mean (red lines, Fig. 9a). A

similar southward shift of the ridge axis was seen

during the 2007 Atlantic hurricane season, which

also featured a strong positive IOD (Bell et al.

2008). Third, the anomalous southerly flow in the

lower atmosphere was confined to the southern

MDR and Gulf of Guinea region, rather than

extending well into the central MDR and the

African Sahel region (Fig. 8a).

The positive IOD also appears to have

affected the La Niña-related convection patterns.

One component of La Niña is an extensive area of

enhanced convection across Indonesia and the

eastern Indian Ocean. However, convection was

suppressed over the eastern Indian Ocean during

ASO 2011 in association with the positive IOD

(Fig. 11), meaning that the La Niña forcing of the

atmospheric circulation was weaker than if no

IOD signal had been present. A similar observation was made by Bell et al. (2008) for the 2007

Atlantic hurricane season."

 

http://www.cpc.ncep.noaa.gov/products/expert_assessment/hurrsummary_2011.pdf

 

 

 

A am not sure that we can blame the weaker West African Monsoon for the 2011 pattern.

There was a stronger one in 2012 and this July with similar increase in stability over the Tropical Atlantic.

 

 

The observations suggest that the IOD

may have acted to limit the 2011 Atlantic hurricane

activity by weakening both the west African

monsoon circulation

[Superstorm93]

Pretty strong wave/low forecast to come off of Africa by most of the global models.

 

If this doesn't fly off of Africa at 20N, then it might be something of interest...

 

(27km HWRF, since the Atlantic is dead...)

 

 

[HurricaneJosh]

OK... If we get to 10 Aug with nothing decent showing up on the long-range Euro or GFS, heads are gonna start to roll.  So y'all better get to work.

 

Just sayin'.

 

[Ed Lizard]

OK... If we get to 10 Aug with nothing decent showing up on the long-range Euro or GFS, heads are gonna start to roll.  So y'all better get to work.

 

Just sayin'.

 

There seems to be decent support for a fish in a week to ten days off Africa.

 

 

However, part of my glass full nature, previous generation (30 km resolution) FIM8 suggests a Tampico Tantalizer.  5% of the GEFS seem to support a decent system down there.  (lowering the goal posts to 1008 gets a couple more BoC and Gulf ensemble cyclones)

 

I'm waiting for the 10 member 30 km ensembles (link that doesn't work suggests someday)  and a 15 km res FIM9 that runs out more than a week...

[Srain]

Off with their heads!1!

[bluewave]

We'll see if we can get at least 1 new named storm before August 20th so we don't end up

behind all the recent years since 2007 for this period.

 

Number of new named storms August 1-20.

 

2010....4

2011....4

2010...1

2009...3

2008...2

2007...2

[Ed Lizard]

Off with their heads!1!

 

 

I still want to know how that voodoo works.  I do see GEFS members now with tropical lows of various strength developing down there, but not 60% of the members.  I wonder if they normalize the number of ensemble members generating a storm to the actual number that developed or something.  That graphic has tended a shade on the optimistic side, a bit like the Canadian in a sense, I haven't seem a storm develop it wasn't excited about, but I've seen it get excited with no resulting storm.  The 90% probs of a BoC storm that didn't develop about a month ago, maybe it was the rare 10% and those probabilities are indeed valid.

 

It is what those ensemble systems do afterwards that counts.  Bone dry in SETX, and a Claudette or Dolly rain w/o serious wind locally system would rock.  Not as much as last Erin, but pattern doesn't seem favorable for that.   12 days out, 1008 mb spaghetti is busy, which is a good sign, I think.  But even 1004 mb spaghetti is interesting.  Not as interesting for Texas/Mexico as Hawaii, but interesting.

 

Edit- one bonus of the Steve graphic, the likely fishiness of the system likely to come off Africa.

[Mike.Ventrice]

A couple of my MJO diagnostics are picking up on a strong CCKW pushing over the dateline this morning:

 

 

Without paying attention to the forecast, these indices are moving into generally favorable phases of Atlantic genesis

[Ed Lizard]

Just an aside, while heat potentials are low offshore SETX, I don't think there is enough of a low TCHP buffer to really protect Galveston, especially since some of that could be bathymetry induced.  But compared to 2005 and 2008, interesting seasons, the Gulf is actually a potentially spooky place for Deep South Texas and Mexico.  Interesting to note what a path of TCHP Katrina had before it.  I'd like a little more heat off the Florida Gulf coast, however.

 

 

[bobbutts]

I think the gust measured at the Corpus Christi Airport during CELIA (140 kt) is definitely way up there.  I'm not aware of another surface-based, non-topographically-enhanced wind reading from an official station in the USA.  (Readings on mountain peaks and the tops of high-rises don't count.)

Pretty amazing when considering storms like Andrew and Camille and my fave, Charley.  

 

 

The wind sensor at the Punta Gorda 

ASOS site, which experienced the eyewall of Charley, stopped reporting after measuring a 

sustained wind of 78 kt at 2034 UTC with a gust to 97 kt at 2036 UTC. Ten minutes later, that 

site reported its lowest pressure, 964.5 mb. Since it is presumed that the center was closest to the 

Punta Gorda site at the time of lowest pressure, and since Charley’s maximum winds covered an 

extremely small area, it is highly likely that much stronger winds would have been observed at 

the site, had the wind instrument not failed. Instrument failures remain a chronic problem in 

landfalling hurricanes.

[IsentropicLift]

Pretty amazing when considering storms like Andrew and Camille and my fave, Charley.  

Do we know for sure what the maximum wind speeds were during Camille?

[bobbutts]

Do we know for sure what the maximum wind speeds were during Camille?

Well not that I'm really qualified to answer, but chances are probably near 0 that any hurricane has ever had a 100% accurate reading of the highest gust it produced..  All we have is a very tiny sample at certain fixed locations (which are rarely/never the location of the highest gust) and have a high failure rate at when attempting to measure that type of wind.

[Amped]

 

Still not to enthuisiatic through September 1st, but at least there's still a chance.

[makojosh]

Just weird, been on Island Hollow for 2 weeks and Belize North coast prior, not even much convection but a he'll of alot of Sal, sorry this recogsoftaware is ****ed

[wxmeddler]

Well not that I'm really qualified to answer, but chances are probably near 0 that any hurricane has ever had a 100% accurate reading of the highest gust it produced..  All we have is a very tiny sample at certain fixed locations (which are rarely/never the location of the highest gust) and have a high failure rate at when attempting to measure that type of wind.

 

Good read on the subject from the Dept. of Commerce's Hurricane Andrew post disaster report:

[wxmx]

There are a couple of weak low pressures nearing the Windward Islands...one nearing 60W and the other closer to 50W. The first one will feel the brunt of the ULL in the SE Bahamas, so it got no chance of developing. The one in the back will have some chances, as the ULL will retrograde west, crossing the GoM and Mexico. In it's wake upper level conditions should become anticyclonic, hence more favorable. Still, the C and E Caribbean conditions will remain adverse for the wave, but they will become increasingly favorable in the W Caribbean. Ridging will weaken a bit in the SE US as a trough passes north, so there's a good chance the wave won't crash into Central America and move into the NW Caribbean and GoM where I expect conditions will be favorable for development.

 

I have increased my chances for the wave/low just E of 50W to develop just a bit, but there are many things that could go wrong still. Time frame for possible development would be days 6+.

[Ed Lizard]

There are a couple of weak low pressures nearing the Windward Islands...one nearing 60W and the other closer to 50W. The first one will feel the brunt of the ULL in the SE Bahamas, so it got no chance of developing. The one in the back will have some chances, as the ULL will retrograde west, crossing the GoM and Mexico. In it's wake upper level conditions should become anticyclonic, hence more favorable. Still, the C and E Caribbean conditions will remain adverse for the wave, but they will become increasingly favorable in the W Caribbean. Ridging will weaken a bit in the SE US as a trough passes north, so there's a good chance the wave won't crash into Central America and move into the NW Caribbean and GoM where I expect conditions will be favorable for development.

 

I have increased my chances for the wave/low just E of 50W to develop just a bit, but there are many things that could go wrong still. Time frame for possible development would be days 6+.

 

The one approaching 50W may have a closed low.

 

Convectively challenged.  And small. but judging from PSU hour 24 hour 850 mb vort forecast, not to small for the Euro to pick up.

[wxmx]

The one approaching 50W may have a closed low.

 

Convectively challenged.  And small. but judging from PSU hour 24 hour 850 mb vort forecast, not to small for the Euro to pick up.

May be, that's why I called it a wave/low. ASCAT shows that there's a clear wind shift, but not sure if it's troughy or a closed low yet. It certainly looks fragile, though.

 

[HurricaneJosh]

Pretty amazing when considering storms like Andrew and Camille and my fave, Charley.  

 

Do we know for sure what the maximum wind speeds were during Camille?

 

With any hurricane, it's hard to know for sure.  But my feeling-- and the feeling of many-- is that Camille at landfall in LA/MS was overestimated.  I personally have come to doubt it was a Cat 5 at landfall.  Chaser/researcher Michael Laca made a really compelling case to me Re: why it probably wasn't.

 

One thing he really pointed out to me was the wind damage in Pass Christian, MS, which was in the right eyewall and should have had the near-max winds.  Pics show that the trees still have leaves and roofs are still on houses.  It does not look like a place that just got swept by Cat-5 winds.  Compare these pics to ones of Andrew's ground zero-- where houses were mowed down and trees were reduced to bare sticks.

[HurricaneJosh]

P.S.  I also feel Celia 1970 has been underestimated and was probably a Cat 4 when it hit TX.  That one had extremely high winds.  Granted, they happened in an apparent microburst chain, but whatever-- the winds happened, they were documented, and they did tremendous damage.

[GaWx]

The combo of analogs for cool US Augusts and neutral negative ENSO (both of which are heavily favored) tells me, as per my earlier posts, that the US is likely to be threatened with a major hurricane this season. I already predicted a few days ago that the US will be hit in 2013 with the first major hurricane since 2005. Since 1950, 38% (24) of the 63 seasons had a major H hit the US.

 

 Since 1950, there have been eight seasons with cool US Augusts that were also within the neutral negative to weak Nina ENSO range based on ONI for ASO. A whopping 7 of those eight seasons had at least one MH hit on the US:

 

-1950: 2 MH, Easy and King

-1964: 2 MH, Hilda and Isbell

-1967: 1 MH, Beulah

-1971: only 1 of the 8 with no MH hit (though there were 2 H hits and Edith had nearly 100 mph sustained winds when it hit LA)

-1974: 1 MH, Carmen

-1985: 1 MH, Elena

-1989: 1 MH, Hugo

-1992: 1 MH with 2 hits, Andrew

 

 So, 1992 was the last season with a cool August and neutral negative to weak La Nina ENSO.

 

 10 MH hits: 1 SC, 2 E FL, 2 W FL, 1 MS, 3 LA, 1 TX

 

 10 MH hit dates: 8/24, 8/26, 9/2, 9/5, 9/8, 9/20, 9/21, 10/3, 10/14, 10/17

 

 So, we're still not even within forecasting sight of the earliest of these major H US hits.

[HurricaneJosh]

Cool stats, Larry-- they give hope!    A couple of quick notes:

 

*  I think there's a strong chance Carmen 1974's landfall in LA will be downgraded to Cat 2 in reanalysis.  The Cat-3 designation was based on pressure, but radar and surface obs suggest it really fell apart as it came in.

 

*  Isbell 1964 was a Cat-2 landfall.  That's how it's listed now, and I don't see any reason why it would be upgraded in reanalysis.

 

Just some FYIs!  These comments don't change the basic premise of your point.

[bluewave]

The next couple of weeks looks fairly hostile for getting a development which could do any

better than Dorian or Chantal. But some of the long range guidance is suggesting that

we may see some viable storms out in the Atlantic toward the end of the month.

 

http://origin.cpc.ncep.noaa.gov/products/people/sweaver/cfs_fcst/images1/wk1.wk2_20130806.gif

 

http://origin.cpc.ncep.noaa.gov/products/people/sweaver/cfs_fcst/images1/wk3.wk4_20130806.gif

[Ed Lizard]

The next couple of weeks looks fairly hostile for getting a development which could do any

better than Dorian or Chantal. But some of the long range guidance is suggesting that

we may see some viable storms out in the Atlantic toward the end of the month.

 

http://origin.cpc.ncep.noaa.gov/products/people/sweaver/cfs_fcst/images1/wk1.wk2_20130806.gif

 

http://origin.cpc.ncep.noaa.gov/products/people/sweaver/cfs_fcst/images1/wk3.wk4_20130806.gif

 

 

Those don't look all that cheerful to me, actually.

 

 

Edit to Add

 

How do we know the Euro seasonal forecast wasn't on to something?

 

[IsentropicLift]

With any hurricane, it's hard to know for sure.  But my feeling-- and the feeling of many-- is that Camille at landfall in LA/MS was overestimated.  I personally have come to doubt it was a Cat 5 at landfall.  Chaser/researcher Michael Laca made a really compelling case to me Re: why it probably wasn't.

 

One thing he really pointed out to me was the wind damage in Pass Christian, MS, which was in the right eyewall and should have had the near-max winds.  Pics show that the trees still have leaves and roofs are still on houses.  It does not look like a place that just got swept by Cat-5 winds.  Compare these pics to ones of Andrew's ground zero-- where houses were mowed down and trees were reduced to bare sticks.

Josh,

 

Is it possible that Camille weakened just prior to landfall in Katrina type fashion leading to a greater discrepency regarding intensity estimates?

[Ed Lizard]

1st 5 day 0% lemon, ever?

[Ed Lizard]

Based on Mimic TPW, early 12Z GFS, satellite, and even the NAM (yes, I know) SIM radar, I am standing with my August 2nd prediction of a glass 1/8th full optimistic on a lemon in the Gulf sometime in the next 3 1/2 days.  1/64th dull on a mandarin, 1/128th on a cherry or tropical/subtropical depression.

 

I know, that is bold, out on a limb.  I am weighing in the fact NHC probably pays more attention to systems near the East Coast and in the Gulf on my 1/th optimism on a lemon.

 

I'll want to see beyond 6 days on the GFS and the other guidance, but Jorge's area of interest last night, the 5 day 0% lemon, already has a lemon, and I may give odds on a mandarin 5-8 days later today.  (Early signs through 6 1/2 days on 12Z GFS positive)  I was feeling in the dumps about the tropics the last couple of days, maybe this GFS run will help turn my frown to a smile.

 

 

 

EDIT TO ADD

 

GFS op seems somewhat supported by its ensembles for Central/East Gulf coast fun and frolics in 10 days...  (Op GFS showed a weak system hitting Florida Panhandle day 10...)  Less fixated on post resolution op details or half res ensemble member details, but general trend, finally maybe action in close...

[TropicalAnalystwx13]

Those don't look all that cheerful to me, actually.

 

 

Edit to Add

 

How do we know the Euro seasonal forecast wasn't on to something?

 

We won't until after the season was passed. Given that pressures the past three months have been below average when the ECMWF forecast them to be much above-average (with an El Nino) though, I wouldn't expect it to be be correct.

[Floydbuster]

P.S.  I also feel Celia 1970 has been underestimated and was probably a Cat 4 when it hit TX.  That one had extremely high winds.  Granted, they happened in an apparent microburst chain, but whatever-- the winds happened, they were documented, and they did tremendous damage.

 

I'd have to agree, Celia likely came ashore with winds near 120 kt, a solid Cat 4 Hurricane. As far as Camille goes, it's movement upon landfall was less that of weakening storms like Ivan and Katrina and more like that of Erin '95 and Gustav. Also, radar images show a very tight circular eyewall near the Mississippi Delta. Camille also had a much, much tighter windfield than almost any modern hurricane along the North Gulf Coast.

 

I doubt it was 165 kt, but 140 kt I can see.