Average hurricane season foreseen by TSR

By: Dr. Jeff Masters , 1:33 PM GMT on June 04, 2009

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The ballots are all in now, and all three major seasonal forecasting groups are calling for a near-average Atlantic hurricane season in 2009--the British private forecasting firm Tropical Storm Risk, Inc. (TSR) has joined the ranks of NOAA and Colorado State University in calling for near-average activity. The latest TSR forecast issued today calls for 10.9 named storms, 5.2 hurricanes, 2.2 intense hurricanes, and an Accumulated Cyclone Energy (ACE) 72% of average. The storm numbers are close to the 50-year average of 10 named storms, 6 hurricanes, and 2 intense hurricanes, and are sharp reduction from their April forecast of 15 named storms, 7.8 hurricanes, and 3.6 intense hurricanes. TSR predicts a 50% chance that this season will be in the bottom 1/3 of years historically, and a 40% chance that U.S. landfalling activity will be in the lowest 1/3 of years historically. TSR gives a 32% chance of a near-normal season, and a 17% chance of a below normal season. TSR rates their skill level as 26% above chance at forecasting the number of named storms, 15% skill for hurricanes, and 19% skill for intense hurricanes.

TSR projects that 3.2 named storms will hit the U.S., with 1.3 of these being hurricanes. The averages from the 1950-2008 climatology are 3.2 named storms and 1.5 hurricanes. Their skill in making these April forecasts for U.S. landfalls is 7 - 18% above chance. In the Lesser Antilles Islands of the Caribbean, TSR projects 0.9 named storms, 0.4 of these being hurricanes. Climatology is 1.1 named storms and 0.5 hurricanes.

TSR cites two main factors for their reduced forecast: a large and unexpected cooling of sea surface temperatures in the tropical Atlantic, and warmer SSTs in the Equatorial Eastern Pacific (which might lead to an El Niño event that will bring high wind shear to the Atlantic). TSR expects faster than than normal trade winds from July - September over the Main Development Region (MDR) for hurricanes over the Atlantic (the region between 10° - 20° N from Central America to Africa, including all of the Caribbean). Trade winds are forecast to be 0.83 meters per second (about 1.7 mph) faster than average in this region, which would create less spin for developing storms, and allow the oceans to cool down, due to increased mixing of cold water from the depths and enhanced evaporational cooling. TSR forecasts that SSTs will cool an additional 0.3°C compared to average over the MDR during hurricane season.

Portlight.org offering relief to Florida flood victims
Tropical disturbance 90L dropped as much as two feet of rain over Northeastern Florida in May, causing severe flooding. In Volusia County, at least 1500 homes were damaged by the flooding, and many of these were in low-income housing projects where the residents did not have flood insurance. Portlight Strategies, Inc., is now working to assist in this area by providing durable medical equipment to the disabled, elderly, or injured that have lost equipment due to the flooding. Specifically, the Portlight team will be assisting with the rebuilding of two homes. One of the homes is owned by a single mother who stood in her house crying, in two feet of water, as she prepared to go to her daughters graduation. The other home is owned by a elderly woman whose husband passed away two years ago. Neither of these families had flood insurance, and can not afford even the lowest interest rate loans provided by FEMA. Portlight's work in Holly Hill, FL will begin on Friday June 12; if you are interested in volunteering, please contact John Wilbanks, john@portlight.org 843-200-6022. There are plenty of stories very similar to these two. Portlight's ability to help is only limited by your assistance, so please consider volunteering or donating today by visiting the Portlight disaster relief blog..


Figure 1. Rainfall amounts over Florida for the two weeks ending on May 27, 2009. Image credit: NOAA.

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Well EPAC is just 1 theory..the other is really my main 1..and thats moving the whole mess NNW over Nicaragua and Honduras and exiting up there somewhere in 3 days or so..."Somewhere"...ok its late... Im
off to bed gn!
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Quoting scottsvb:



Low doesnt have to be associated with a tropical wave or disturbance..lol you know that..:)


Of course =P

Thing is....if the GFS is right and the low really is going to form with the convection south of Panama.....my money is on the area of convection west of Panama along 85W south of 10N:



It has great upper-level diffluence over it and guess what, there's an 850mb vort max under it as well:



If I were a model I'd be forecasting the low to initiate right there, and if it did, it's already pretty dang far west. Then your EPAC theory may turn out to be correct, and our only hope for the Caribbean will be the trough-split, which was my original theory to begin with lol, as you can see in my blog.
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Quoting bballerf50:

lol sorry scott....had to laugh


laugh about what?
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Quoting Levi32:


If low doesn't form....there will be nothing to move into the EPAC period...



A low doesnt have to be associated with a tropical wave or disturbance..lol you know that..:)
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Quoting Levi32:


If low doesn't form....there will be nothing to move into the EPAC period...

lol sorry scott....had to laugh
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Quoting scottsvb:
If low doesnt form..it will move west into the EPAC....


If low doesn't form....there will be nothing to move into the EPAC period...
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If low doesnt form..it will move west into the EPAC....
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Quoting scottsvb:
Well..again..how much land impact from Nic-Honduras....where does it emerge...NE tip or closer to Belize...

The pattern is pretty well set up right..about anything in the carribean moving NNE-NE after leaving Honduras.

A guesscast will be 2 things.. 1 I mentoioned above about it staying weak until it gets to the Epac thru Nicaragua...other is it moving north off Honduras to near western cuba and NE south of the keys towards Andros Island in the bahamas by later next week.


Well now that is something we really can't even guestimate until the low has formed, but I think that if it reaches 15N while still east of 85W, it's not going into the East Pacific. The ridge over the EPAC is strong and will be nosing northward. The trough split will cause a significant weakness in the ridge to the north that I don't see the low passing up if it makes it to 15n without already being well inland over Central America.
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Well..again..how much land impact from Nic-Honduras....where does it emerge...NE tip or closer to Belize...

The pattern is pretty well set up right..about anything in the carribean moving NNE-NE after leaving Honduras.

A guesscast will be 2 things.. 1 I mentoioned above about it staying weak until it gets to the Epac thru Nicaragua...other is it moving north off Honduras to near western cuba and NE south of the keys towards Andros Island in the bahamas by later next week.
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Quoting gator23:


absolutely. I think she was just concerned about the panic some of the other users create. Any early guesses as to where it may be heading 96 hours out?


Well 96 hours is relative depending on when and where the low actually forms, but assuming the GFS is right for now, I'd say it would drift north towards the weakness in the ridge, probably ending up near western Cuba eventually.
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Quoting Levi32:
lets wait till we see at least 3 models showing something developing at 72hrs out.

Oh but we do have 3 models :P

Sounds like we're all pushing for the same caution that is necessary with these things, but I see no harm in using our imagination and think ahead. That's what makes it fun for me.


absolutely. I think she was just concerned about the panic some of the other users create. Any early guesses as to where it may be heading 96 hours out?
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lets wait till we see at least 3 models showing something developing at 72hrs out.

Oh but we do have 3 models :P

Sounds like we're all pushing for the same caution that is necessary with these things, but I see no harm in using our imagination and think ahead. That's what makes it fun for me.
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Quoting TampaSpin:


i don't disagree with your thinking....but people get way excited for no reason when something like this is over hyped for no reason yet......lets wait till we see at least 3 models showing something developing at 72hrs out.


Agreed, right now there is no system to speak of. By Monday we will know for sure. Patience young padawan
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Good nite everyone.......
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Quoting scottsvb:
Yeah there is alot of possibilities...like it remaining weak while moving over central america..into the EPAC..then feeling the ridge over southern mexico and being a threat to them in 5-7 days out....lmao! hehe


Haha yeah it's possible, but I think our best bet is with the far western Caribbean because of the trough split. We'll see how it evolves.
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FAA Could Close 20 Weather Offices

The federal government yesterday moved forward with a controversial proposal that would close weather offices at 20 regional air traffic control centers around the country and instead provide controllers with forecasts from two central units in Maryland and Missouri.....
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Yeah there is alot of possibilities...like it remaining weak while moving over central america..into the EPAC..then feeling the ridge over southern mexico and being a threat to them in 5-7 days out....lmao! hehe
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Quoting scottsvb:
Levi is pretty much right on... but here is the thing everyone is jumping the gun on and not doing.. the short term forecast! Short term forecast is key to any system development. What happens in the short term (within 48hrs) is what matters. Models % rates drop every 12hrs and increase their % decrease each time. After 72hrs its pretty much a 1/4 chance anything will be correct and after 120hrs..its less than 10% correct.
Now with this said...we dont have anything out there in the SW Carribean...and nothing to form really until 72hrs out ....and thats in the 25% category.. Questions will arise:

1. Will there be a Disturbance?

2. Where will the Disturbance be?

3. Over land? Near Nic/Hond boarder?

4. What is happening in the layers of the atmo?

5. Whats the steering flow over the GOM and W Atlantic.

There are many more factors also...but the main point is... we dont know forsure anything really more than 2-3 days out..especially in the tropics when models are performing differently. Right now.. we have nothing...I wouldnt put much into anything until models converge on something in a certain area..mainly the GFS along with the ECMWF...and only then we need to short term conditions of the 5 listed above to see how fast this develops and if it develops @ all.. a weaker system remember will push further WNW with the LLF.
Anyways Ill leave it @ that.. I could go into scientific detail..but I rarely do that cause it could be very confusing..probably what alot just read in here.. LOL!


Yup we can't draw conclusions this early with no system yet to speak of, but hey, speculating is what we do :). It's fun to think out the possibilities here.
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Levi is pretty much right on... but here is the thing everyone is jumping the gun on and not doing.. the short term forecast! Short term forecast is key to any system development. What happens in the short term (within 48hrs) is what matters. Models % rates drop every 12hrs and increase their % decrease each time. After 72hrs its pretty much a 1/4 chance anything will be correct and after 120hrs..its less than 10% correct.
Now with this said...we dont have anything out there in the SW Carribean...and nothing to form really until 72hrs out ....and thats in the 25% category.. Questions will arise:

1. Will there be a Disturbance?

2. Where will the Disturbance be?

3. Over land? Near Nic/Hond boarder?

4. What is happening in the layers of the atmo?

5. Whats the steering flow over the GOM and W Atlantic.

There are many more factors also...but the main point is... we dont know forsure anything really more than 2-3 days out..especially in the tropics when models are performing differently. Right now.. we have nothing...I wouldnt put much into anything until models converge on something in a certain area..mainly the GFS along with the ECMWF...and only then we need to see the short term conditions of the 5 listed above to see how fast this develops and if it develops @ all.. a weaker system remember will push further WNW with the LLF.
Anyways Ill leave it @ that.. I could go into scientific detail..but I rarely do that cause it could be very confusing..probably what alot just read in here.. LOL!
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Quoting CybrTeddy:
Oh switch off those model runs, I'm not going that direction. Come along now R2.



Win.
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Well guys goodnight! We'll see what the models say tomorrow!
Member Since: September 3, 2007 Posts: 3 Comments: 1519
Oh switch off those model runs, I'm not going that direction. Come along now R2.

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Quoting Patrap:
That ULL is a Vigorous one and has blown thru here tonight.

Fall Like in NOLA almost.
Cool ,Dry Continental Air moving in,Turned off the A/C too.


Thats the culprit that might produce this low in the Carr.
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That ULL is a Vigorous one and has blown thru here tonight.

Fall Like in NOLA almost.
Cool ,Dry Continental Air moving in,Turned off the A/C too.
Member Since: July 3, 2005 Posts: 426 Comments: 128736
953. JRRP
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Pats loop above is already showing the energy all the way down into the Carribean...
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Pat that low is the one im talking about...
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Quoting CatastrophicDL:

Tampa, I haven't been doing this as long as some people on here, but a remnant low at the end of a trough all the way to the Honduras/Nicaragua area? I can't remember a trough in the US extending that far south.


All it needs is a small piece of energy to break off....it happens very fast in the early season. Late in the year this happens more often.
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Quoting winter123:
wow.. looks like the ITCZ is exploding and its about to eat panama alive. ugh ill be back tomorrow at 5pm

Link


Weren't the models predicting that the system would form from Panama?
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Member Since: July 3, 2005 Posts: 426 Comments: 128736
Quoting CatastrophicDL:

Tampa, I haven't been doing this as long as some people on here, but a remnant low at the end of a trough all the way to the Honduras/Nicaragua area? I can't remember a trough in the US extending that far south.


Always on the tail in early season and late season is when this occurs......
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Levi and i just said the same thing except i said it in simple terms........LOL
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Quoting TampaSpin:
It appears to me that the tail end of this low spinning near the Alabama and Mississippi will produce a very large tail into the Carribean and stalls with a low forming.....JMO....

LOOK AT THIS LOOP

Tampa, I haven't been doing this as long as some people on here, but a remnant low at the end of a trough all the way to the Honduras/Nicaragua area? I can't remember a trough in the US extending that far south.
Member Since: September 3, 2007 Posts: 3 Comments: 1519
Quoting sporteguy03:


TS, I don't disagree there, but why is it a big deal to discuss what the models show days out, I read weather discussions all the time that talk about model information 5 days out from ECMWF to GFS. If you just look and compare to the actual conditions how is that wishcasting?


If someone on here says it is going to hit "insert place here" 10 days out that is wishcasting.

Every year this blog goes through this....just amazes me.


i don't disagree with your thinking....but people get way excited for no reason when something like this is over hyped for no reason yet......lets wait till we see at least 3 models showing something developing at 72hrs out.
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Member Since: July 3, 2005 Posts: 426 Comments: 128736
It appears to me that the tail end of this low spinning near the Alabama and Mississippi will produce a very large tail into the Carribean and stalls with a low forming.....JMO....

LOOK AT THIS LOOP
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Is trough split an official term? Maybe you guys don't use it.

For clarity Drak, I mean when a trough swings down into the southern states and then gets squeezed off by the high and a piece of the trough gets left behind as a small upper feature in the GOM or NW Caribbean. It's one of the main causes of early-season TC formation.
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Quoting TampaSpin:


Yep there is always a low in that area...but, that area is also where the GFS develops this Ghost....Been trying to figure out where this Ghost comes from myself.

Look at the tropical wave on CIMSS and satellite. I've been watching it for two days. It has maintained its vorticity and until just a bit ago, a fair amount of convection, and isn't it about to enter an area of higher TCHP? Let me know your thoughts!
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Quoting Drakoen:



I'm not really seeing what you are talking about.


Trough split with the shortwave currently moving through southeastern states....

It was what the GFS initially had this Caribbean system forming from in the beginning.

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Quoting Drakoen:


Condition are forecasted to become quite favorable in the Caribbean. Like I said before it is not common that you see the GFS bomb out like this in the short-range. I remember when it initialized Dean as barely a tropical storm when it was a full blown hurricane.


True. We shall wait and see....
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Quoting Levi32:
I'm still not liking the way the GFS is handling the trough split. It shoots most of it east of Florida and another little piece down towards the Yucatan Channel. It handled this much better 2 days ago.



I'm not really seeing what you are talking about.
Member Since: October 28, 2006 Posts: 57 Comments: 30565
936. JRRP
12Z run

00Z run

the same position
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Quoting TampaSpin:


There is alot of wishcasting.....MOdel are seldom correct this far out. When it gets to 72 hrs. then maybe if a blob is around then one might take it serious.


TS, I don't disagree there, but why is it a big deal to discuss what the models show days out, I read weather discussions all the time that talk about model information 5 days out from ECMWF to GFS. If you just look and compare to the actual conditions how is that wishcasting?


If someone on here says it is going to hit "insert place here" 10 days out that is wishcasting.

Every year this blog goes through this....just amazes me.
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Quoting CatastrophicDL:
Tampa, Isn't there pretty much always vorticity there with the stationary low? I'm still thinking the low will form from the tropical wave at 10N 47W. With the speed it is moving, the timing would be right.


Yep there is always a low in that area...but, that area is also where the GFS develops this Ghost....Been trying to figure out where this Ghost comes from myself.
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Quoting bballerf50:
Drak:

You seem unusually optimistic about this...


Condition are forecasted to become quite favorable in the Caribbean. Like I said before it is not common that you see the GFS bomb out like this in the short-range. I remember when it initialized Dean as barely a tropical storm when it was a full blown hurricane.
Member Since: October 28, 2006 Posts: 57 Comments: 30565
I'm still not liking the way the GFS is handling the trough split. It shoots most of the upper trough east of Florida and sends another little piece down towards the Yucatan Channel. It handled this much better 2 days ago.
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931. Relix
I am still looking for this low you guys speak about XD
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The 00Z GFS so far is pretty aggressive with the Caribbean System...
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Quoting Drakoen:
developing it immediately as the system comes of land.


Run seems similar to 18z
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Quoting sporteguy03:
Wishcasting??? Who is wishcasting all I see on here is a few bloggers talking about model output and comparing their trends, isn't that why this blog is here?


There is alot of wishcasting.....MOdel are seldom correct this far out. When it gets to 72 hrs. then maybe if a blob is around then one might take it serious.
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Tampa, Isn't there pretty much always vorticity there with the stationary low? I'm still thinking the low will form from the tropical wave at 10N 47W. With the speed it is moving, the timing would be right.
Member Since: September 3, 2007 Posts: 3 Comments: 1519

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.