Thoughts on 2013 Atlantic Hurricane Season

['CaneFreak]

My point still remains valid. Instability is NOT a big factor. All those seasons still ended up with significant activity.

http://rammb.cira.colostate.edu/project ... tatins.gif

2011. very stable from about jul15- end of season

2010 again, except for 2 brief spikes very stable from aug-end of season

http://rammb.cira.colostate.edu/project ... tatins.gif

2012 was even more stable but i cant find the map

2013:

http://www.ssd.noaa.gov/PS/TROP/TCFP/da ... t_THDV.gif

here is an example of an unstable atlantic:

2003

http://rammb.cira.colostate.edu/project ... ns2003.gif

monumental difference from last few seasons

so yes, the tropical atlantic is in the midst of a multi year trend of stable conditions from 2010 to now.

[TropicalAnalystwx13]

1. Tropical instability is not a pattern.
2. Do you have any sound data to back up this claim? Multiyear pattern over which time periods?
3. Things CAN, DO, and WILL change DRASTICALLY in short periods of time in the tropical Atlantic. They always have and they always will.

Models aren't perfect - even within a week. We still do not understand tropical cyclogenesis all that well and thus the reason that models don't perform that well with it. That's why we have projects like PREDICT. We also have a limited amount of good upper air data over the oceans and that will always be a problem when you are talking about a large body of water. Upper air data is critical to weather analysis and forecasting.

the tropical instability has been a multi-year pattern so i doubt it will change drastically in a week, though i hope it would.

http://rammb.cira.colostate.edu/project ... tatins.gif

2011. very stable from about jul15- end of season

2010 again, except for 2 brief spikes very stable from aug-end of season

http://rammb.cira.colostate.edu/project ... tatins.gif

2012 was even more stable but i cant find the map

2013:

http://www.ssd.noaa.gov/PS/TROP/TCFP/da ... t_THDV.gif

here is an example of an unstable atlantic:

2003

http://rammb.cira.colostate.edu/project ... ns2003.gif

monumental difference from last few seasons

so yes, the tropical atlantic is in the midst of a multi year trend of stable conditions from 2010 to now.

So tell me again, how did 2010 turn out from late August to the end of the season?

Oh right...Danielle, Earl, Fiona, Gaston, Helene, Igor, Julia, Karl, Lisa, Matthew, Nicole, Otto, Paula, Richard, Shary, Tomas.

[boca]

Is the Azores high capable of drying out the whole Eastern Atlantic even with the more southern position.Also with the lack of disturbances have anything to do with the colder than normal Indian Ocean.

[tolakram]

I see those graphs, but I think the point is ... what do those graphs have to do with hurricane season. If it was so obvious, why aren't any pros paying attention to them? At some point you'll have to come to the conclusion that they are all missing the obvious, or you are wrong.

Personally, I figure I'm usually wrong if I think I see something the pro's don't.

Have you looked for active hurricane seasons with below normal instability? 2005 doesn't stand out as unusually above normal, plus there were very few waves that year, yet ....

In 2007 tropical instability in the MDR was below normal when both Dean and Felix formed.

There's a much bigger picture that instability in a region. It's a nice graph, but I'm not sure it means anything because I've never seen any discussion on the significance of being 1.25C below normal for instability. What does that mean and why is it important?

[ConvergenceZone]

Wow, it's amazingly quiet out there. Just 1 little old invest in the pacific, and nothing at all in the Atlantic. It seems more like May or early June rather than late August....

There's no doubt we will get SOME activity beginning in September, but not the crazy active season the NHC was predicting, probably not even close........This is just my opinion, but I'm starting to think they may have blown their "really active" predication bad this year......

[beoumont]

warnings were issued LATE with Andrew... only about 18 hours lead time for hurricane force winds

I guess one could conclude the actual specific warning was a little later than average. The small size of the hurricane wind field (30 miles out from the center) in all directions, and the increase in speed by 50% (from 15 mph to 22) before landfall contributed to the actual "lateness" of the warning.

Example: Hurricane warnings for Hugo, 1989, were issued on the 21st of Sept. at 10Z. The landfall of that large hurricane's eye was at 4z on the 22nd in S. Carolina. That was the previous major hurricane USA landfall: same 18 hours, but less time to prepare, as wind field was much larger.

Once Hurricane Andrew turned west, 65 1/5 hrs. before landfall, it was pretty obvious and made so to the public, that a hurricane was headed towards S. Florida. Hence the "lead" time was plenty adequate. Mass evacuation northward on all major highways from S. Florida was well underway when the actual warning went out.

A hurricane watch went up approx. 33 hours before any hurricane winds occurred in S. Florida; when Andrew was a 100 mph storm, pressure 974 mb, moving west at 15. It came inland moving 22 mph at 922 mb.

<<<<<< ZCZC MIAWRKAP4 LOC
TTAA00 KNHC DDHHMM
BULLETIN
HURRICANE ANDREW ADVISORY NUMBER 24...
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT SAT AUG 22 1992

...HURRICANE WARNINGS FOR NW BAHAMAS...
...A HURRICANE WATCH FOR PORTIONS OF FLORIDA...

THE GOVERNMENT OF THE BAHAMAS HAS ISSUED A HURRICANE WARNING FOR THE
NORTHWEST BAHAMAS WHICH INCLUDES ANDROS ISLAND AND ELEUTHERA ISLAND
NORTHWARD THROUGH GRAND BAHAMA AND GREAT ABACO.

A HURRICANE WATCH IS ISSUED FOR THE FLORIDA EAST COAST FROM
TITUSVILLE SOUTHWARD THROUGH THE FLORIDA KEYS INCLUDING DRY
TORTUGAS...EFFECTIVE AT 5 P.M. EDT.

HURRICANE ANDREW CONTINUES TO MOVE ON A WESTWARD COURSE TOWARD THE
BAHAMAS AND FLORIDA. HURRICANE CONDITIONS COULD BE EXPERIENCED IN
THE NW BAHAMAS LATE SUNDAY AND IN FLORIDA SOMETIME MONDAY.

AT 5 PM EDT...2100Z...THE CENTER OF ANDREW WAS LOCATED NEAR
LATITUDE 25.9 NORTH...LONGITUDE 70.4 WEST OR ABOUT 615 MILES
...990 KM...EAST OF MIAMI FLORIDA.

ANDREW IS MOVING TOWARD THE WEST NEAR 15 MPH...24 KM/HR... AND THIS
GENERAL MOTION IS EXPECTED TO CONTINUE THROUGH THE NEXT 24 HOURS OR
MORE.

MAXIMUM SUSTAINED WINDS ARE NEAR 100 MPH...160 KM/HR...AND
SOME FURTHER STRENGTHENING IS POSSIBLE.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 30 MILES... 45 KM...
FROM THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP
TO 85 MILES...140 KM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 974 MB...28.76 INCHES. >>>

[beachbum123]

The bad economy has made my .02 cents about worthless, which is why I don't post much...lol..but Imo 5 named storms before the end of August is pretty active.

Like some of you I believe this years predictions are a little high, but I wouldn't call this a dead season and I for sure wouldn't hang up your hat just yet. There is still plenty of time for many more stormes to form, I think we are just warming up.

We've had seasons where we went way over the predicted numbers and seasons where we were way under.

Who remembers 1983?
They predicted 8 named storms and expected 5 of them to become hurricanes, we actually only saw 4 named, three of which became hurricanes. The first storm was Alicia forming on Aug. 15th.

Now over 60 African systems formed and moved west but fizzled out quickly once they reached the Lesser Antilles. The wind shear was unusually strong throughout the Caribbean and open Atlantic, and disrupted convection in areas of disturbed weather so they could not develop. The gulf and Atlantic north of the Bahamas and east of Florida were the only areas with minimal shear, these areas are where the 4 stormes formed.

I personally am enjoying this wacky season!

[Meso]

I personally, am loathing this sad excuse for a hurricane season.

As a side note, I don't agree with the stigma against people wanting an active season either, a lot of us are trackers because we enjoy it. Not wanting an active season would be like a storm chaser not wanting supercells.

Five named storms may not be too bad generally, but the storms have been awful. At no stage has the Atlantic looked like it is capable of producing a decent storm. The conditions have just been hostile and when you can make it through almost the end of August without a hurricane, that says something about the season. I'm not convinced that we will get the season that everyone has been saying we will. In July everyone was saying "wait until August" and now everyone is saying "wait until September". If we continue waiting much longer it's going to turn into "just wait until next year".

A lot will depend on whether the Atlantic conditions get their act together and stop being so hostile. If the NavGem were correct things could change quickly, but I am still expecting to see a low season with less than average numbers. Maybe something like 10/3/1

Here is to hoping otherwise though, I always look forward to June each year because the tracking can begin, this lack of activity leaves me rather bored.

[tolakram]

Revisiting vertical instability.

http://www.ssd.noaa.gov/PS/TROP/TCFP/atlantic.html

Here is the product description (link at the bottom of the page):

THDV: The average vertical instability parameter, defined as the vertical average temperature difference between the equivalent potential temperature of a parcel lifted from the surface to 200 hPa, and the saturation equivalent potential temperature of the environment.

So right now the average tropical Atlantic vertical instability is running somewhere between 1 and 1.5 degrees C below normal.

https://en.wikipedia.org/wiki/Convective_instability

When air rises, moist air cools at a lower rate than dry air. That is, for the same vertical movement, a parcel of moist air will be warmer than a parcel of dry air. This is because of the condensation of water vapor in the air parcel due to expansion cooling. As water vapor condenses, latent heat is released into the air parcel. Moist air has more water vapor than dry air, so more latent heat is released into the parcel of moist air as it rises. Dry air does not have as much water vapor, therefore dry air cools at a higher rate with vertical movement than moist air. As a result of the latent heat that is released during water vapor condensation, moist air has a relatively lower adiabatic lapse rate than dry air. This makes moist air generally less stable than dry air (see convective available potential energy). The dry adiabatic lapse rate (for unsaturated air) is 3 °C (5.4 °F) per 1,000 vertical feet. The moist adiabatic lapse rate varies from 1.1 °C to 2.8 °C (2 °F to 5 °F) per 1,000 vertical feet.

The combination of moisture and temperature determine the stability of the air and the resulting weather. Cool, dry air is very stable and resists vertical movement, which leads to good and generally clear weather. The greatest instability occurs when the air is moist and warm, as it is in the tropical regions in the summer. Typically, thunderstorms appear on a daily basis in these regions due to the instability of the surrounding air.

The ambient lapse rate differs in different meteorological conditions, but, on average, is 2 °C (3.5 °F) per 1,000 vertical feet.

So my question is; is 1.5C a significant difference?

[ninel conde]

it would seem to be. some good news however. JB has tweeted.

Joe Bastardi ‏@BigJoeBastardi 29m

End of summer heat resembles 1999 and 2003, both late start hurricane season with major impact on US with storms

should be noted that in 1999 aug had 2 cat4's both of which had formed by now and 2003 has already had 3 cat1 canes by now.

clearly atalntic tropical instability isnt the only negative factor. we have a texas ridge that has effectively cut off the GOM and west carib from significant development and it also is creating a wnw flow across the east coast meaning no close in development there as well. mid level dry air and a series of ULL's and tutts would make one think an el nino is occuring. if only one factor was negative then i would say climatology would be able to overcome it but we have multiple negative factors and so far the 2 models to look at, euro and GFS are indicating climo isnt kicking in just yet.

[Hurricaneman]

it would seem to be. some good news however. JB has tweeted.

Joe Bastardi ‏@BigJoeBastardi 29m

End of summer heat resembles 1999 and 2003, both late start hurricane season with major impact on US with storms

should be noted that in 1999 aug had 2 cat4's both of which had formed by now and 2003 has already had 3 cat1 canes by now.

clearly atalntic tropical instability isnt the only negative factor. we have a texas ridge that has effectively cut off the GOM and west carib from significant development and it also is creating a wnw flow across the east coast meaning no close in development there as well. mid level dry air and a series of ULL's and tutts would make one think an el nino is occuring. if only one factor was negative then i would say climatology would be able to overcome it but we have multiple negative factors and so far the 2 models to look at, euro and GFS are indicating climo isnt kicking in just yet.

how come the conditions are more El Nino like the TUTT and cooler NE and Midwest and Atlantic dry air when we are closer to a weak La Nina

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products

[Hammy]

I'm not sure if this means anything or if I'm just going crazy from the lack of activity, but I've noticed this morning that there seems to be a lot more of a westerly low-level flow in the Atlantic and it also seems to be slightly more convectively active than it has in possibly weeks (even if it still isn't that much overall.)

[ROCK]

so its the Texas ridge fault?....sorry but have to call BS on that...

the ATL can and will change on a dime. It just needs light. the MJO pulse might be it.

I knew I shouldnt have read the last few pages of this thread. Got my blood pressure up...

[ROCK]

I'm not sure if this means anything or if I'm just going crazy from the lack of activity, but I've noticed this morning that there seems to be a lot more of a westerly low-level flow in the Atlantic and it also seems to be slightly more convectively active than it has in possibly weeks (even if it still isn't that much overall.)

yep its very soupy down there. NAVGEM is sniffing....

[Frank2]

Per Beoumont's post about Andrew - my mental reflex is to say "good old days" - but those weren't...

Per his post, I remember that 5 p.m. advisory - that's when it began to sink in that South Florida was toast. About 10 that Saturday evening I went to the local Publix Supermarket, and the scene was out of Titanic - no kidding - a tremendous crowd of people all wanting avoid the pending disaster and unsure what to take with them...

In the mob I met an old cycling friend of mine - who was in total denial and said she was there "just to buy a few things" and commented, "Isn't it crowded for this late in the evening" - I wasn't sure whether she was drunk or on the verge of an emotional disconnect...

After leaving the store I remember a Suburban in the parking lot - full of gear, even on the roof rack - apparently they were going to drive all night - smart thinking, because they next day leaving was next to impossible...

But, having prayed about it I left at Sunset the next evening and drove - alone on the deserted Florida Turnpike - to my sister's (d. 2006) house in Palm Beach County, and spent the relatively wind-free night there - and the next 10 days, until I could find another house to live in, my rental house in South Dade missing half it's roof (the decision to leave helped to save my life), so not good memories, but there it is...

[ninel conde]

so its the Texas ridge fault?....sorry but have to call BS on that...

the ATL can and will change on a dime. It just needs light. the MJO pulse might be it.

I knew I shouldnt have read the last few pages of this thread. Got my blood pressure up...

just part of a larger pattern. the ridge causes a east coast trof and we can see another front moving se in the northwest flow today. lots of storms can form with a texas ridge but it does put a crimp in US landfall forecasts.

[Hurricaneman]

I'll say this but it looks like we may have a few favorable spots, the east coast and the GOM so watch for home brew the next week or so IMO

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products

[Hammy]

throwing the 2001 comparison out there again, I did a bit of comparing between 2001 and this year over Africa and the IO for Aug 20.

http://www.ncdc.noaa.gov/gibbs/image/MET-7/IR/2013-08-20-15
http://www.ncdc.noaa.gov/gibbs/image/MET-5/IR/2001-08-20-15

http://oiswww.eumetsat.org/IPPS/html/MSG/IMAGERY/IR108/COLOR/FULLDISC/
http://www.ncdc.noaa.gov/gibbs/image/MET-7/IR/2001-08-22-15

It could be meaningless but the satellite presentations are fairly similar, indicating similar conditions. And note in both cases the slow increase of moisture over equatorial Africa between Aug 20 and 22.

[sunnyday]

Just heard on the radio that NOAA has said that it now predicts a 70% chance of an active storm season. I wonder how long until they say 50%, 30%, and then say this will not be an active year, to say the least. It's looking that way, but that's only my opinion.

[sunnyday]

I feel exactly like you, Meso. Rather bored....

Just to clarify that I would never wish a storm to damage anyone's life or property. However, when you enjoy watching storms develop over a period of time, it is an exciting hobby.