Atlantic Tropical Action 2014

[Shawn]

Nothing looking too flashy anywhere close to the East Coast for quite a while from this morning's modeling.  The lemon turned out to be nothing.... I do know a front will stall through the Carolinas along with some disturbances going off the coast over the next couple of days.. but nothing to really do much in the form of tropical development.

 

It's still early, but I'm not quite sure how active the tropics can get this season.

[gulfcane]

Nothing looking too flashy anywhere close to the East Coast for quite a while from this morning's modeling.  The lemon turned out to be nothing.... I do know a front will stall through the Carolinas along with some disturbances going off the coast over the next couple of days.. but nothing to really do much in the form of tropical development.

 

It's still early, but I'm not quite sure how active the tropics can get this season.

 

It's July 9th and we've had a landfalling category 2 hurricane in NC. I'm not sure how much activity you were expecting by this time, but we're above average. And the Great El Nino of 2014 that was shoved down our throats and buried into our subconscious as a reason to doubt the hurricane season is a no show. So all the hurricane season forecasts which were lowballed due to the Great El Nino of 2014 will need to be revised for the August update. (looking at you, NOAA, CSU). 

[phil882]

It's July 9th and we've had a landfalling category 2 hurricane in NC. I'm not sure how much activity you were expecting by this time, but we're above average. And the Great El Nino of 2014 that was shoved down our throats and buried into our subconscious as a reason to doubt the hurricane season is a no show. So all the hurricane season forecasts which were lowballed due to the Great El Nino of 2014 will need to be revised for the August update. (looking at you, NOAA, CSU). 

 

These comments are a little annoying... because so far, the season is progressing exactly as expected, with widespread unfavorable conditions in the MDR.

 

Part of this is due to the higher than normal SSTs across the EPAC, promoting more convection in the EPAC. This convection modifies the heating profile of the atmosphere, enhancing the low-level monsoon trough with its cyclonic circulation in the EPAC, and promoting upper-level ridging over the same region. If you have an anomalous upper-level anticycone that parked along 10-15N across the EPAC, it also modifies where you see corridors of anticyclonic wavebreaking (AWB) downstream of the upper-level rdiging, which are hypothesized to draw high PV air form the mid-latitudes deep into the tropics, and act as source regions for TUTTs. If the upper-level ridging stays over the EPAC, then the corridors of AWB also remain entrenched over the western Atlantic, and this increases vertical wind shear over the Caribbean and MDR in the Atlantic.

 

Arthur could be considered a stereotypical TC that develops during an El Nino ENSO cycle. It did not form from an AEW, but rather a onshore generated MCV which received baroclinic support for convective enhancement when it moved offshore. Thanks to the AWB pattern downstream of the ridging in the EPAC forcing a PV streamer deep into the Caribbean, the higher vertical wind shear that would often be observed off the east coast was located further south, and the system found itself under light anticyclonic flow north of the TUTT / PV streamer corridor. This is why some here have suggested that El Nino can sometimes result in more non-tropical originating disturbances that become TCs in poleward latitudes, since the more favorable conditions are located poleward of the MDR where TUTTs and PV streamers reign supreme. Arthur certainly fits the bill here, regardless of its ultimate intensity. 

 

[Mike.Ventrice]

These comments are a little annoying... because so far, the season is progressing exactly as expected, with widespread unfavorable conditions in the MDR.

 

Part of this is due to the higher than normal SSTs across the EPAC, promoting more convection in the EPAC. This convection modifies the heating profile of the atmosphere, enhancing the low-level monsoon trough with its cyclonic circulation in the EPAC, and promoting upper-level ridging over the same region. If you have an anomalous upper-level anticycone that parked along 10-15N across the EPAC, it also modifies where you see corridors of anticyclonic wavebreaking (AWB) downstream of the upper-level rdiging, which are hypothesized to draw high PV air form the mid-latitudes deep into the tropics, and act as source regions for TUTTs. If the upper-level ridging stays over the EPAC, then the corridors of AWB also remain entrenched over the western Atlantic, and this increases vertical wind shear over the Caribbean and MDR in the Atlantic.

 

Arthur could be considered a stereotypical TC that develops during an El Nino ENSO cycle. It did not form from an AEW, but rather a onshore generated MCV which received baroclinic support for convective enhancement when it moved offshore. Thanks to the AWB pattern downstream of the ridging in the EPAC forcing a PV streamer deep into the Caribbean, the higher vertical wind shear that would often be observed off the east coast was located further south, and the system found itself under light anticyclonic flow north of the TUTT / PV streamer corridor. This is why some here have suggested that El Nino can sometimes result in more non-tropical originating disturbances that become TCs in poleward latitudes, since the more favorable conditions are located poleward of the MDR where TUTTs and PV streamers reign supreme. Arthur certainly fits the bill here, regardless of its ultimate intensity. 

 

 

 

Couldn't agree with you more Phil. While my purpose here is not to single out anyone's personal thoughts, it should be noted that the MDR has been hostile this year thus far. Arthur was a rare case of tropical cyclone that was seeded by a MCV, not associated with a tropical wave, nor potential vorticity streamer. We've had a number of easterly waves push across the MDR but the shear is just too strong, in addition to an increased frequency of TUTTs spinning around in the sub-tropical Atlantic. The El Nino has weakened in SSTA expression, but it is likely the result of the upwelling phase of the same oceanic Kelvin wave that altered the base state in the Pacific. Just a destructive interference of an intraseasonal feature on the net low-frequency pattern.

[TropicalAnalystwx13]

On the topic of wind shear, does anyone have any ideas what's causing the subtropical jet to be so amplified? My first thought was obviously the warmer waters in the Pacific, but last time I checked, the atmosphere isn't really responding like it should be.

 

[Shawn]

It's July 9th and we've had a landfalling category 2 hurricane in NC. I'm not sure how much activity you were expecting by this time, but we're above average. And the Great El Nino of 2014 that was shoved down our throats and buried into our subconscious as a reason to doubt the hurricane season is a no show. So all the hurricane season forecasts which were lowballed due to the Great El Nino of 2014 will need to be revised for the August update. (looking at you, NOAA, CSU). 

 

I should have put more science instead of making it sound like an opinion, but after reading what Phil posted afterwards, I'll leave it to the pros.  The season is far from over of course, but things are looking slow...

 

Opinion* Arthur just got lucky to do what he did off the coast imo... especially since he originated over land (his origins).

[hurricaneman]

Looking at some of my analog years most of them don't have a second storm form from anywhere from Early to mid august so there may be a pretty much month long period where there is nothing of interest to track but I do believe that once we hit that point that is when the atlantic is going to pop and I do believe that the east coast may have to deal maybe up as far as New England because I see in the long range{up to late July} no real change in the pattern from the Ohio Valley trough we just had with Arthur

[phil882]

On the topic of wind shear, does anyone have any ideas what's causing the subtropical jet to be so amplified? My first thought was obviously the warmer waters in the Pacific, but last time I checked, the atmosphere isn't really responding like it should be.

 

 

It isn't? From these maps, it looks like there is reduced wind shear in the EPAC due to an enhanced time-mean ridge. The irrotational outflow resulting from TCs and convection associated this upper-level ridge are contributing to the enhancement the subtropical jet downstream in the Atlantic basin. Also note the anomalously low and easterly vertical wind shear between 20-40N in the Western Atlantic basin, the same region where Arthur developed. 

 

This pattern in my opinion possesses many similarities to what you would expect if El Nino conditions were influencing the atmosphere. This downstream atmospheric response to enhanced SSTs in the EPAC is not directly connected with how the atmosphere is reacting upstream of the Nino 3.4 region. 

[calm_days]

(An earlier animation is available on the prior page)

 

Here is an up to date, wider view.

Shown here is [what as an amateur I can only describe as saturated, slow moving air over the gulf region, where a few small ULLs that were interacting with the cyclogenesis of 91L before melting into what is seen in the above and previous image] the amorphous GOM feature that slowed down the trough still remaining in place. 

 

 

There is what may be anomalous ULL activity although I don't know if there are any analogs for this in past years.  Something similar to this region has been here for a while now; this is the strongest appearance it has shown recently.  Will it stay together and keep moving?  It may not be tropical but it has a path similar to one a tropical system might. 

[Sunny and Warm]

you talking about the ULL over northern Mexico or north of Cuba?  In either case, I don't see development.

[IsentropicLift]

The Euro and GFS both like the southeast coast in the 7-10 day range. Something to keep an eye on.

[calm_days]

you talking about the ULL over northern Mexico or north of Cuba?  In either case, I don't see development.

 

Yes, it is the one in northern Mexico.  I'm also not sure how it would develop tropically but find the steady movement west to be unique; if this were happening in the winter I'm sure it would be more noticed, but, this also doesn't usually happen in the winter. 

 

[Ground Scouring]

SSTA in the MDR have undertaken a pretty dramatic reversal over the past several weeks, with significant warming off the W African coast. Although drought conditions in the Sahel will likely mean more SAL outbreaks this season, the warmer SSTA would help offset low instability somewhat. With El Niño likely to be weak at best in time for peak season (ASO), the odds of a busier-than-expected season look better every day.

[wxmx]

Yes, it is the one in northern Mexico.  I'm also not sure how it would develop tropically but find the steady movement west to be unique; if this were happening in the winter I'm sure it would be more noticed, but, this also doesn't usually happen in the winter. 

 

 

Retrograding ULLs are rather common during summer at or near the tropics (as mid/upper level ridges establish around 30N-35N). There's no way this one will develop into a tropical cyclone because once it gets into the sea the SSTs will be just too cold.

[Ground Scouring]

Does anyone have a record of the NAO at the time of every major hurricane strike on the FL peninsula, which includes the Keys, after 1900? I know that a -NAO, depending on whether it's east or west based, would potentially shift the Bermuda-Azores High farther west, thereby favoring potential East-Coast threats. Yet from what I've seen, most of the biggest FL hits occurred in a +NAO state. Can anyone clarify the truth?

 

For reference, here are the major FL peninsula hits after 1900. (The data up to 1935 come from wxmx's online map tool, which will hopefully be updated shortly to include the 1936-1950 reanalysis data.) A hit in this case is when a storm produces major hurricane winds on a portion of the FL coastline.

 

1906-10-18 10:00:00 - 105 kt

1909-10-11 18:00:00 - 100 kt

1917-09-29 02:00:00 - 100 kt

1919-09-10 07:00:00 - 130 kt (FL Keys)

1921-10-25 20:00:00 - 100 kt (Tampa Bay)

1926-09-18 12:00:00 - 125 kt (Great Miami)

1928-09-17 00:00:00 - 125 kt (San Felipe II/Okeechobee)

1929-09-28 13:00:00 - 100 kt

1933-09-04 05:00:00 - 110 kt

1935-09-03 02:00:00 - 160 kt (Labor Day)

1944-10-18 21:00:00 - 105 kt

1945-09-15 19:30:00 - 115 kt

1947-09-17 16:30:00 - 115 kt (Ft. Lauderdale)

1948-09-22 05:00:00 - 115 kt

1949-08-26 23:00:00 - 115 kt

1950-09-05 17:00:00 - 105 kt (Easy)

1950-10-18 05:00:00 - 115 kt (King)

Donna 1960 - Cat. 4

Betsy 1965 - Cat. 3

Eloise 1975 - Cat. 3

Elena 1985 - Cat. 3

Andrew 1992 - Cat. 5

Opal 1995 - Cat. 3

Charley 2004 - Cat. 4

Ivan 2004 - Cat. 3

Jeanne 2004 - Cat. 3

Dennis 2005 - Cat. 3

Wilma 2005 - Cat. 3

[andyhb]

Does anyone have a record of the NAO at the time of every major hurricane strike on the FL peninsula, which includes the Keys, after 1900?

 

1948 to present: ftp://ftp.cdc.noaa.gov/Public/gbates/teleconn/nao.reanalysis.t10trunc.1948-present.txt

[Kory]

Does anyone have a record of the NAO at the time of every major hurricane strike on the FL peninsula, which includes the Keys, after 1900? I know that a -NAO, depending on whether it's east or west based, would potentially shift the Bermuda-Azores High farther west, thereby favoring potential East-Coast threats. Yet from what I've seen, most of the biggest FL hits occurred in a +NAO state. Can anyone clarify the truth?

 

For reference, here are the major FL peninsula hits after 1900. (The data up to 1935 come from wxmx's online map tool, which will hopefully be updated shortly to include the 1936-1950 reanalysis data.) A hit in this case is when a storm produces major hurricane winds on a portion of the FL coastline.

 

1906-10-18 10:00:00 - 105 kt

1909-10-11 18:00:00 - 100 kt

1917-09-29 02:00:00 - 100 kt

1919-09-10 07:00:00 - 130 kt (FL Keys)

1921-10-25 20:00:00 - 100 kt (Tampa Bay)

1926-09-18 12:00:00 - 125 kt (Great Miami)

1928-09-17 00:00:00 - 125 kt (San Felipe II/Okeechobee)

1929-09-28 13:00:00 - 100 kt

1933-09-04 05:00:00 - 110 kt

1935-09-03 02:00:00 - 160 kt (Labor Day)

1944-10-18 21:00:00 - 105 kt

1945-09-15 19:30:00 - 115 kt

1947-09-17 16:30:00 - 115 kt (Ft. Lauderdale)

1948-09-22 05:00:00 - 115 kt

1949-08-26 23:00:00 - 115 kt

1950-09-05 17:00:00 - 105 kt (Easy)

1950-10-18 05:00:00 - 115 kt (King)

Donna 1960 - Cat. 4

Betsy 1965 - Cat. 3

Eloise 1975 - Cat. 3

Elena 1985 - Cat. 3

Andrew 1992 - Cat. 5

Opal 1995 - Cat. 3

Charley 2004 - Cat. 4

Ivan 2004 - Cat. 3

Jeanne 2004 - Cat. 3

Dennis 2005 - Cat. 3

Wilma 2005 - Cat. 3

You can say the same thing about significant Central Gulf Coast hurricanes.  Andrew (1992), Opal (1995), Ivan (2004), Katrina (2005), Rita (2005), Ike (2008) are just a few of some recent ones.  

[wxmx]

For the -NAO theory, I would look at data where the Bermuda ridge was present...so I would remove hits from the west/south. Also, since we are looking at steering currents, I would look for overall activity, not only stronger systems, which would also involve upper level conditions. Finally, since we can't be completely sure what's the temporal involvment of the NAO on the cyclone lifetime, longer ranges averages would make more sense than just looking at the NAO state the day a cyclone hit....and since we should look at overall activity, we probably should look at the average of 1-3 months.

[wxmx]

With the above guidelines, I did a small research for what the average pattern looked like for Aug-Sep of the most active years for E FL. What I found is that more than NAO, is high latitude blocking what may influence low latitude ridging. It makes sense, as strong NAO blocking would also promote troughiness upstream, but high latitude blocking, would lower heights latitudinally in the northern midlatitudes and rise them in the subtropics...which is a more stable configuration for east-west steering currents. And if on top on that there's a -PNAish configuration, then it would be better for pumping the Bermuda ridge.

 

I also did the Aug and Sep graphics separately, and they yielded similar results.

 

[Ground Scouring]

With the above guidelines, I did a small research for what the average pattern looked like for Aug-Sep of the most active years for E FL. What I found is that more than NAO, is high latitude blocking what may influence low latitude ridging. It makes sense, as strong NAO blocking would also promote troughiness upstream, but high latitude blocking, would lower heights latitudinally in the northern midlatitudes and rise them in the subtropics...which is a more stable configuration for east-west steering currents. And if on top on that there's a -PNAish configuration, then it would be better for pumping the Bermuda ridge.

 

I also did the Aug and Sep graphics separately, and they yielded similar results.

Your analysis is interesting, because I followed your methodology and used the same base climatology (1981-2010), but used the V2 reanalysis for major landfalls hitting E FL prior to 1950. My data include such notable hits as the 1926 and 1928 hurricanes. My results are similar in some respects, with relatively lower heights over the Gulf/W Caribbean and higher heights centered near Bermuda, but strikingly different in terms of the placement of high-latitude blocking, with the blocking very clearly centered just NE of Hudson Bay. Most notably, there is a very strong +NAO/+PNA combination, in complete contrast to the -NAO/-PNA look on your graph. Moreover, the Bermuda High is oriented less zonally than in your graph, with a NW-to-SE rather than E-to-W orientation from SE Canada to the Sargasso Sea. Maybe different climate patterns produce similar results, but the two graphs are so strikingly different for some reason.

 

[wxmx]

Your analysis is interesting, because I followed your methodology and used the same base climatology (1981-2010), but used the V2 reanalysis for major landfalls hitting E FL prior to 1950. My data include such notable hits as the 1926 and 1928 hurricanes. My results are similar in some respects, with relatively lower heights over the Gulf/W Caribbean and higher heights centered near Bermuda, but strikingly different in terms of the placement of high-latitude blocking, with the blocking very clearly centered just NE of Hudson Bay. Most notably, there is a very strong +NAO/+PNA combination, in complete contrast to the -NAO/-PNA look on your graph. Moreover, the Bermuda High is oriented less zonally than in your graph, with a NW-to-SE rather than E-to-W orientation from SE Canada to the Sargasso Sea. Maybe different climate patterns produce similar results, but the two graphs are so strikingly different for some reason.

 

 

The +PNA (not overly strong, just hugging the W Coast) and +NAO, with a strong Bermuda ridge would promote the Midwest trough, which is a known pattern for east coast hits, including E FL if the Bermuda ridge is strong/west displaced enough.

 

I agree there could be different N Hem patterns that would yield similar results. In this case, instead of latitudinally enhancing the subtropics ridging (zonal flow), we get a pattern which enhances the Bermuda ridge longitudinally, with a more amplified pattern.

[Roger Smith]

Greetings from contest headquarters. It seems rather quiet so, in case it gets busy near end of July or I forget, just wanted to mention to the considerable number of people who read this thread and who entered the contest, there is a monthly component and I have been entering placeholder forecasts for those who didn't drop in after their seasonal entry, just so your score won't fall off too much before you have a chance to try the more active months ahead. I based these placeholders on the "normal" amounts scaled down where necessary to meet your seasonal forecasts. In most cases the decimal amounts while lower than the normals still kept everyone at forecasts of 1/0/0 for June and 1/1/0 for July which is what most of the actual forecasts were also. I'm going to keep doing this in August and September but you might want to drop in and post a monthly yourself (as about half the contestants have been doing) because these provisionals only score 50% of what an actual forecast that is made by the entrant makes.

 

Your seasonal forecast gets some part of 50/100 of the points available and the monthlies get the other 50/100. June was worth 4 and July 6, so if nothing more happens this month, you are not that far behind the pack of active monthly forecasters and could still take the contest with good predictions in more valuable August (12) September (16) and October (10). Regardless, I will post two lists of scores, one for the combined contest, and one for seasonal predictions alone. So if your main interest was the seasonal forecast, that will be a separate contest result.

 

As for revisions, unlike previous years, mid-season revisions will not help very many contestants under the rules in play. In previous years we assigned percentage values to first predictions and two subsequent updates. This year, you can only improve your score with a revision if that revision scores higher than your original after a time penalty of 1% per day. On a practical basis almost any revision offered after mid-July (we are already at a 45% reduction of score as of today) is not going to beat your original forecast, so the revisions are for peace of mind but if you foresee a huge increase (in most cases no huge decrease is possible) you would score more since a season that ended up being 15/10/5 (above all our forecasts and above normal) would definitely score close to zero on forecasts made in most cases. One or two of us could get about 20/50 for that outcome. But at this point, if you don't foresee changes greater than 2/2/2 from your seasonal made June 1st, then you can't improve score by more than 9 (three times (4+2)/2) and as 45% of 50 is 22.5, I think you need to have a revision greater than 4/4/3 which would amount to 26 points to gain anything now. In other words, the contest forecasts are pretty much locked in from early June and nobody can gain at this point unless it's a very substantial change. After August 1st almost no revision could possibly score more points than the originals.

[wxmx]

Looking at Kyle MacRitchie's site, I see not everything is lost for the Atlantic basin. For most of his graphics he uses 4 CFS v2 Ensembles and an average of those (kind of a superensemble). These paint a different picture than the well known CFS v2 ENSO plumes and analysis we know from the NCEP. I don't know where the difference lies, all I know is that the NCEP plumes are based off 40 members.

 

Short and medium range 850mb wind anomalies between 7.5S and 7.5N show mostly easterly wind anomalies. This causes SSTAs to cool to a little below average according to those analysis. As a result, It also reverses the above average wind shear anomalies that have plagued west of 40W in the basin.

 

U-Wind 850mb

 

SSTAs

 

Atlantic shear (hotlink, time sensitive)

[bluewave]

First drop in the shear on a daily basis to just below normal since early May.

But the SST's over the Tropical Atlantic remain below normal along with

the instability. The drop in shear coincides with the ENSO cooling especially

in Nino 1-3.

 

 

Cooling of all Nino regions from last week except 4 which held steady.

................1+2...3.....3.4....4

 

02JUL2014  1.4 1.0   0.4   0.3
09JUL2014  1.1 0.6   0.3   0.3

 

 

 

[wxmx]

There's a decent period of -NAO coming up. That will lower pressures and weaken trade winds in the MDR. Lower pressures are more fertile for cyclogenesis and weak trade winds will allow the MDR SSTs to heat up ... both enhance instability. Let's see how this pans out next 2 weeks.

[wxmx]

First drop in the shear on a daily basis to just below normal since early May.

 

In line with the CFS shear forecast I posted above yours. Let's see if it stays that way for most of the season as forecasted.

[IsentropicLift]

Nice to see a drop in shear to coincide with the warming SST. Maybe this season won't end up as terrible as first thought.

[bluewave]

In line with the CFS shear forecast I posted above yours. Let's see if it stays that way for most of the season as forecasted.

 

Yeah, it will be interesting to see how things develop. Even if the shear weakens, we'll have to see how

much development we can get with the cooler and more stable than normal Tropical Atlantic. Maybe

this will continue to be another north of 20N season for ACE like we saw with Arthur.

 

 

[icebreaker5221]

Not sure why NHC is ignoring that easterly wave south of the CVs.  GFS has a TS in 36 h, and ECMWF sorta likes it too. 

 

Doesn't have much potential for longevity, but needs at least a lemon imo. 

 

 

 

[icebreaker5221]

UL divergence should be enhanced and shear should be favorable for at least the next 48 h courtesy the passage of a Kelvin wave: