Atlantic Tropical Action 2013

[TropicalAnalystwx13]

The March 2013 ECMWF forecast for MSLP across the Atlantic during the July-August-September period was released today.

 

It looks a lot better than February's in regards to the fact that it doesn't show much of the Atlantic and eastern Pacific with high pressures; it's more average this time around. Though given the current setup with sea surface temperatures, this is still probably a bit too bullish.

 

[Ed Lizard]

Paging OkPowdah to the tropical thread. OkPowdah to the tropical thread, please.

 

 

I wish I knew what that meant.  With limited exceptions, when Josh is happy I am happy for him.  Should I be happy for him?

[am19psu]

I wish I knew what that meant.  With limited exceptions, when Josh is happy I am happy for him.  Should I be happy for him?

OkPowdah is a poster who knows a lot more than I do about the QBO/tropical season interaction. The flip in QBO should allow for a higher tropopause this season in the off-equatorial Atlantic, which means the potential for deeper convection and therefore more latent heat to release. QBO obviously isn't the only factor, but the flip should be a good thing, all else being equal.

[HM]

 

I love the discussion here... something that I've been meaning to create is a seasonal predictor of the cold tongue that develops in the Gulf of Guinea during summer. As TropAnalyst stated, this will dictate the mean location of the ITCZ... where a colder than average cold tongue promotes a northward ITCZ shift bringing much needed rains to the Sahel, whereas the warmer cold tongue promotes increased convection over sub-Saharan Africa, and especially the Guinea Highlands. Some research that I never published was with regards to cold vs warm cold tongue in the Gulf of Guinea and tropical cyclogenesis locations. There are far more genesis events near the coast of West Africa during years where the cold tongue is warmer than average, whereas mean genesis is shifted over the western MDR during years with a colder than average cold tongue. 

 

Still gathering my thoughts on the # of storms this year. Something I need to do within the upcoming month.

Thanks for the thoughts. I remember some older correlations had to do with prior year's precipitation (say, e.g., August-November 2011's precipitation on the 2012 season) across the Gulf of Guinea's bordering land areas. Some how, they tied that precipitation into the following year's monsoonal circulation which had an effect on the number of named storms (more precip=more storms essentially). The excess water could also have an effect on the SST too.

It would be interesting to see if your data set followed this correlation still with precipitation.

[Ed Lizard]

Off season talk time, after HM's response to an excellent 'Met 101' teacher met (he can teach!), and Bendy Tree Mods posts, I am actually gaining insight on why elements of Dr. Gray's pre-AMO predictions based on regression analysis probably worked.  I know why his 1997 busted so badly, I can theorize some (or it is stated, essentially, in the Klotzenbach season forecast guide) why some of the new regression analysis tools have better than climatology odds.

 

Reading posts, strict amateur, I see some apparently positive indicators for an above average and more "exciting" (to me, a Cat 5 fish on satellite is "exciting") and a few neutral to slightly negative indicators.  I am hoping slightly fewer, but better quality, storms, and my landfall weeniesm (but not my YouTube Hurricane Charley type weeniesm, things like if there could have been chasers at Mindanao in the Philippines is down, a daylight landfall Cat 4 hitting Melbourne, FL, not so much) is way down from getting older.  5 years ago I was a full on IMBY I want to see a Cat 5 from inside the eye weenie.

[LongBeachSurfFreak]

To me, 2012 was a dead year.  Sure, there were a ton of named systems, but it was 90% crap.  I mean, c'mon-- 19 storms, with only two barely reaching 100 kt?  Lame.

 

There were a few hawt moments-- like Ernie's Yucatan landfall and Sandy's Cuba landfall-- but that was it.  Looking back, Isaac was basically a big, under-performing irritant-- remarkably like Irene, another loose, low-end Cat 1 that everyone and their grandma chased.

 

It was a dead year.  Most of the activity was atmospheric static.

 

I find this funny from a guy who is from LI (if I remember correctly) I take it you're pissed you missed 946 into New Jersey? (That is certainly not static) (It would have been amazing if you followed me with you're camera as I stood in 3 foot surging saltwater inundating a freshwater lake as the sky lit up like a severe thunderstorm with transformer explosions as trees went down like domino's and a car on fire floated by.) Enough on the Sans.

 

Back on topic I have been following dust levels traveling West off the Sahel. It seems that the elevated dust levels in recent years have influenced the lack of deep convection in the MDR despite other favorable factors. Does anyone have any insight into current precip patterns in the Sahel and resultant soil moisture? As well as precip forecasts for the Sahel moving forward? I am talking more on the cusp of the Sahara where dryer conditions add to normal Saharan dust storms and have created the increase in dust in the MDR in recent years.

[bluewave]

Good points on the vertical instability.  The last three seasons have featured below average instability in the MDR during peak season, which has almost certainly been a limiting factor in preventing deep -80 C cloud tops associated with TCs that have been almost commonplace in every basin except the Atlantic since 2010. 

 

How much of a factor this was in limiting the development of major hurricanes in the MDR both these years is debatable.  I suspect poorly-timed genesis events encountering unfavorable shear and dry air before RI could begin was more often the culprit than not, but I suspect the lack of instability didn't help things. 

 

e.g. 2011: (although 2010 and 2012 were similar)

 

It will be interesting to see if we have a continuation of the unusually stable air over the Tropical

Atlantic again this coming season. The current increase in stability since 2010 was preceded 

by drier conditions from 2006 on relative to the previous 7 seasons.

 

 

 

 

 

 

 

[TropicalAnalystwx13]

A 5-day Tropical Weather Outlook becomes operational this season.

 

Example:

 

SHOWERS AND THUNDERSTORMS ASSOCIATED WITH AN AREA OF LOW PRESSURE LOCATED ABOUT 1175 MILES EAST-NORTHEAST OF THE NORTHERN LEEWARD ISLANDS HAVE BECOME A LITTLE BETTER ORGANIZED. ALTHOUGH UPPER-LEVELS WINDS ARE ONLY MARGINALLY FAVORABLE FOR DEVELOPMENT...THEY ARE EXPECTED TO BECOME MORE FAVORABLE DURING THE NEXT DAY OR TWO. THIS SYSTEM HAS A MEDIUM CHANCE...40 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES WEST-NORTHWESTWARD AT 10 MPH. AFTER THAT TIME...THE SYSTEM IS EXPECTED TO MOVE GENERALLY NORTHWESTWARD AND HAS A HIGH CHANCE...80 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS.

 

[Ed Lizard]

A 5-day Tropical Weather Outlook becomes operational this season.

 

Example:

 

 

 

 

The whole lemon/mandarin/cherry talk on these threads in the Summer will become lemon/mandarin or lemon/lemon (possible) or mandarin/cherry or cherry oh cherry oh baby?

 

(Delete if needed)

[TropicalAnalystwx13]

/begin sarcasm

 

The ECMWF ensemble mean is making the forecast for this upcoming season easy.

 

/end sarcasm

 

[hurricaneman]

When you combine the shear and low instability with all the positive factors we had last year you get what we call quantity and not quality

[thewxmann]

So what are commons predictors for tropical Atlantic instability? I'd like to see more major canes and less namewasters this season.

[Eyewall2005]

[SlantStickers Anonymous]

Great video, some of those analogs were pretty interesting. Hopefully we end up with an active season that shows us some love instead of the fish.

Can't wait.

[HurricaneJosh]

I find this funny from a guy who is from LI (if I remember correctly) I take it you're pissed you missed 946 into New Jersey? (That is certainly not static) (It would have been amazing if you followed me with you're camera as I stood in 3 foot surging saltwater inundating a freshwater lake as the sky lit up like a severe thunderstorm with transformer explosions as trees went down like domino's and a car on fire floated by.) Enough on the Sans.

 

I'm not really pissed because it wasn't a hurricane.  The winds were impressive for an extratropical low, but it was no hurricane-- no core, no eyewall, nothing that I dig about hurricanes.  Central pressure is only one metric, and not the main one.  The 1938 hurricane had a pressure only a few millibars lower but winds astronomically higher (105 kt vs. Sandy's 70 kt) because it actually had a core with a gradient.  So I'm cool.

[hurricaneman]

 

These are pretty close to what I was thinking in terms of analogs but may have to add 2004 if the ENSO goes into +.3 or higher which, but if I were to pick out an area of highest risk I would go South Carolina, North Carolina, Virginia, Long Island, Massachusetts, Rhode Island, Florida, Georgia and Connecticut.

 

Areas of heightened risk aka moderate risk are Alabama, Mississippi, Louisiana, Maine

 

Areas of slight risk, Texas, Delaware, Maryland, New Jersey

 

This is based on what usually happens when the PDO Ridge is strong at this time of year it tends to translate to a small ridge over the Southeast US and can cause 2 tracks, Up the eastern seaboard or through Florida into the gulf.

 

I'm also thinking that the instability in the Atlantic will come up to above normal around May or so based on past analogs

 

So I'm anticipating a very high impact year which I surely hope doesn't come to fruition

[TropicalAnalystwx13]

These are pretty close to what I was thinking in terms of analogs but may have to add 2004 if the ENSO goes into +.3 or higher which, but if I were to pick out an area of highest risk I would go South Carolina, North Carolina, Virginia, Long Island, Massachusetts, Rhode Island, Florida, Georgia and Connecticut.

 

Areas of heightened risk aka moderate risk are Alabama, Mississippi, Louisiana, Maine

 

Areas of slight risk, Texas, Delaware, Maryland, New Jersey

 

This is based on what usually happens when the PDO Ridge is strong at this time of year it tends to translate to a small ridge over the Southeast US and can cause 2 tracks, Up the eastern seaboard or through Florida into the gulf.

 

I'm also thinking that the instability in the Atlantic will come up to above normal around May or so based on past analogs

 

So I'm anticipating a very high impact year which I surely hope doesn't come to fruition

[Srain]

Some interesting trends via the March update of the Seasonal European Tropical forecast. The Eurosip suggest a much different pattern than what we saw last year with normal to lower pressures across the MDR and into the Caribbean and Gulf. It is noteworthy that the Eurosip is also suggesting lower pressure over Texas and near or slightly above normal temps and normal rainfall as well for the June/July/August time frame. We will see.

 

March 2013 MSLP

 

March 2012 MSLP

 

[Ed Lizard]

Some interesting trends via the March update of the Seasonal European Tropical forecast. The Eurosip suggest a much different pattern than what we saw last year with normal to lower pressures across the MDR and into the Caribbean and Gulf. It is noteworthy that the Eurosip is also suggesting lower pressure over Texas and near or slightly above normal temps and normal rainfall as well for the June/July/August time frame. We will see.

 

March 2013 MSLP

03222013 March Season Eurosip Tropics_tercile32summary_mean32sea32level32pressure_332months.gif

 

March 2012 MSLP

03222013 March 2012 Eurosip MSLP Tropics_tercile32summary_mean32sea32level32pressure_332months.gif

 

We'll need a tropical storm or low end Cat 1 or I suspect an active fire season for Texas.  Not liking Spring so far at all around these parts.  CPC AMJ rainfall forecasts probs are not happy at all.

[OKpowdah]

Paging OkPowdah to the tropical thread. OkPowdah to the tropical thread, please.

 

 

 

Hahaha thanks for the shout out. I actually just came in this thread because I wanted to throw around a few things as the QBO shifts

 

To start, here's the equatorial zonal wind anomalies so far this spring. Can see the -QBO holding on by its thumbs, with the westerlies starting to descend and near 30mb (first days with a + anomaly since July 2011 WOW)

 

 

The current profile fits the 330 degree phase of my "index" pretty well. Descending westerlies above 30mb, easterlies centered around 70mb, and neutral right around 30mb.

 

 

The phase I would be keying in on for hurricane season based on average "residence time" is 60 degrees.

 

 

Here's the tropopause pressure correlation for phase 60. It's a pretty weak signal, with on average zero correlation in the MDR and negative in the central Atlantic. This may support more disturbances in the central Atlantic more recurvatures of any TCs that do form.

 

(Negative = a higher tropopause height, Positive = a lower tropopause height)

 

 

Here's the same map for phase 90. Notice the equator to off-equator dipole tightens and intensifies, and the Gulf and NW Caribbean is under a very low correlation (high tropopause height) and that band extends across the Atlantic between 15N and 30N.

 

That dipole that I mention is tightest and most intense around phase 120.

 

 

So if the QBO reaches phase 90 during the season (essentially a full-blown +QBO), this suggests an increased TC threat in the NW Caribbean and Gulf. Of course this is one factor, and probably still relatively insignificant, but something that's interesting to discuss anyway

[icebreaker5221]

 

 

Hahaha thanks for the shout out. I actually just came in this thread because I wanted to throw around a few things as the QBO shifts

 

To start, here's the equatorial zonal wind anomalies so far this spring. Can see the -QBO holding on by its thumbs, with the westerlies starting to descend and near 30mb (first days with a + anomaly since July 2011 WOW)

 

The current profile fits the 330 degree phase of my "index" pretty well. Descending westerlies above 30mb, easterlies centered around 70mb, and neutral right around 30mb.

 

The phase I would be keying in on for hurricane season based on average "residence time" is 60 degrees.

 

Here's the tropopause pressure correlation for phase 60. It's a pretty weak signal, with on average zero correlation in the MDR and negative in the central Atlantic. This may support more disturbances in the central Atlantic more recurvatures of any TCs that do form.

 

(Negative = a higher tropopause height, Positive = a lower tropopause height)

 

Here's the same map for phase 90. Notice the equator to off-equator dipole tightens and intensifies, and the Gulf and NW Caribbean is under a very low correlation (high tropopause height) and that band extends across the Atlantic between 15N and 30N.

 

That dipole that I mention is tightest and most intense around phase 120.

 

So if the QBO reaches phase 90 during the season (essentially a full-blown +QBO), this suggests an increased TC threat in the NW Caribbean and Gulf. Of course this is one factor, and probably still relatively insignificant, but something that's interesting to discuss anyway

 

 

Great stuff right there.  While I'm now fairly convinced that a +QBO should support colder cloud tops and deeper convection over the Gulf / Caribbean, have you actually found this to be associated with a greater occurance of genesis and/or more major hurricanes?  Higher CAPE alone is not necessarily associated with greater genesis frequency or more intense / symmetric storms, mostly because cold mid-level temps that cause a bump in CAPE are often associated with dry contitnetal air and/or greater shear.  If there is an analogous tradeoff associated with rising tropopause heights triggered by the stratosphere alone, it's not immediately obvious to me.  In which case, these findings are especially useful!

[andyhb]

Josh will like the current SSTs in the Atlantic Basin should they maintain themselves roughly into the season, almost the entire MDR, Caribbean and Gulf are all above normal...

[Superstorm93]

The MDR (85W-20W and 10N-20N) is about a degree above normal. 

 

Looks very interesting in these early days of Spring

 

[TropicalAnalystwx13]

A number of forecasts came out today...

 

- CSU released their general thinking with an above-average to extremely active season.

- Joe Bastardi released his updated thinking today...16 named storms, 12 hurricanes, 5 major hurricanes. End to the major hurricane drought, several hits [potentially majors] on the East Coast thanks to a similar pattern to the 1950s. Gulf Coast is still at risk with 2005 as an analogue. 

- ImpactWeather released their forecast a while ago. 16-20 named storms, 7-9 hurricanes, 2-4 major hurricanes.

My forecast for a hyperactive season with many landfalls continues. I'd typically forecast 17-18 named storms, but with an increase in subtropical and non-tropical-originating storms the past few years, I've bumped this up to 19-21 named storms. An increase in instability, favorable wind shear pattern, and [not that it needs to be said] warm Atlantic all favor stronger storms forming in traditional areas. The pattern at this point, if it's being interpreted correctly, definitely hints to a high impact year.

[Mike.Ventrice]

Signs are pointing to an active season, especially SSTs in tropical Atlantic.  Slightly worried that another push of warm water from the West Pac to East Pac as another MJO makes its way across the IO and over the Pac during early April. Still with the -PDO, not expecting much ENSO forcing.. so I think I'm going with 17/8/3, with increased prospects of landfall over Gulf States, including FL. Based off of last year's SSTs in the Gulf of Guinea being quite warm, usually follows with the next year JAS cold tongue being anomalously strong -> shifts mean genesis activity over the western MDR instead of up close and personal to West Africa. I am seeing 2007 as an analog too which wasn't as active as past years. I guess time will tell, especially if we get any early season TCs which would provide evidence of an active year to come.

[OKpowdah]

Great stuff right there.  While I'm now fairly convinced that a +QBO should support colder cloud tops and deeper convection over the Gulf / Caribbean, have you actually found this to be associated with a greater occurance of genesis and/or more major hurricanes?  Higher CAPE alone is not necessarily associated with greater genesis frequency or more intense / symmetric storms, mostly because cold mid-level temps that cause a bump in CAPE are often associated with dry contitnetal air and/or greater shear.  If there is an analogous tradeoff associated with rising tropopause heights triggered by the stratosphere alone, it's not immediately obvious to me.  In which case, these findings are especially useful!

 

Yes. That's some of the research I was posting in a thread I started a little while back. I just bumped it up.

 

Obviously there are other factors involved, but this is pretty convincing to me:

 

[Eyewall2005]

 

http://www.weatherbell.com/2013-Hurricane-Season-Forecast

[Eyewall2005]

Would like to here (promets) views on 400mb pattern  and how much might this amount to very active deep tropics and season overall.

 

2012 

 

2013

 

[Ed Lizard]

^^ If one follows JB on the Twitters, 400 mb is his new tool for both tornado and TC long range prediction.  Not his only tool.  But apparently his new favorite.

[bluewave]

Would like to here (promets) views on 400mb pattern  and how much might this amount to very active deep tropics and season overall.

 

2012 

 

2013

 

 

I haven't read anything specific about the significance of temperatures at the 400 mb height level. The temperature 

profile is one that you would expect to see in an Atlantic tripole pattern. All those analogs were the result of a strong -AO/NAO winter pattern.

 

 

Dr. Masters had a great post on this pattern back in 2010.

 

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=1444&tstamp=