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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NEXRAD Radar
Jacksonville, Base Reflectivity 0.50 Degree Elevation Range 124 NMI
Member Since: July 3, 2005 Posts: 420 Comments: 127536
Quoting RitaEvac:
It could be another stupid swirl that goes where it wants


Stupid swirls this year seem to have Mobile and the Florida Panhandle targeted as their final resting spot before moving inland! I just hope this pattern changes before July - September gets here!
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Quoting WPBHurricane05:
GFS 12Z zoomed in on Florida. Link

Main model page. Link


That zoom in is something to see for sure. That looks like a decent storm.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Nice blob off of Panama, don't expect any development but for blob fans this might be exciting.
Member Since: May 27, 2009 Posts: 0 Comments: 4436
We are really getting a good downpour on the west side of Jacksonville. Having trouble posting the link but it's a really good soaker!
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Keeper, I think 352 is the most I've even seen you say at one time. LOL


wait till a storm comes calling
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Quoting CatastrophicDL:

What a guy - you are keeping your halo clean! I'm impressed! I think of future AOI in 120 hours or so may come from the tropical wave that is at 40W. What are your thoughts?


Isn't that the same wave you've been watching since about 37W?
Member Since: April 26, 2009 Posts: 3 Comments: 3667
GFS 12Z zoomed in on Florida. Link

Main model page. Link
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Quoting Orcasystems:


I stand corrected :)

What a guy - you are keeping your halo clean! I'm impressed! I think of future AOI in 120 hours or so may come from the tropical wave that is at 40W. What are your thoughts?
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Orca I hope that did not sound arrogant. If it did i am sorry. I am not that kind of person. later. God Bless. Taylor
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Later gang.

Got to get back to reviewing our City's CEMP & COOP.
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Well the Caribbean low is still 120 hours out if it even forms, a lot of time in between.
Member Since: May 27, 2009 Posts: 0 Comments: 4436
Quoting chsweatherintern2009:


Thanks for the advise,but I do have a good amount of experence with weather. As my name says yes I am a intern at a weather station, but I also have usage of a lot of material and models. Thanks for the Advise orca


I stand corrected :)
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Global MSLP
Member Since: July 19, 2008 Posts: 43 Comments: 4051
Quoting Orcasystems:


I am going to make an assumption from your nick... your new..and your studying weather. You would do well to watch some of the regulars here, there are some pros, and a lot of seasoned amateurs who know there stuff.

Trust me.. if someone gets out of line with hype.. they will be pulled back into line.. let one of the regulars do it.. its safer, and you do not get a name for yourself that you may not deserve.



Thanks for the advise,but I do have a good amount of experence with weather. As my name says yes I am a intern at a weather station, but I also have usage of a lot of material and models. Thanks for the Advise orca
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Member Since: July 19, 2008 Posts: 43 Comments: 4051
Keeper, I think 352 is the most I've even seen you say at one time. LOL

FutureMet
, and it doesn't do much with it after 120 hours either.
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Quoting chsweatherintern2009:


I wasn't saying you or anybody in specific.I just know how thing get when people start to depend on the models. I just know how people get. they cry wolf. that is all I was saying hope i did not offend anyone


I am going to make an assumption from your nick... your new..and your studying weather. You would do well to watch some of the regulars here, there are some pros, and a lot of seasoned amateurs who know their stuff.

Trust me.. if someone gets out of line with hype.. they will be pulled back into line.. let one of the regulars do it.. its safer, and you do not get a name for yourself that you may not deserve.

Member Since: October 1, 2007 Posts: 81 Comments: 26511
It looks like the 18Z NAM is starting to jump onboard.

Link
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The mean time frame of the genesis of this system is too equivocal at the moment. The ECMWF does not expect this system to form until 120hhrs from now.

Member Since: July 19, 2008 Posts: 43 Comments: 4051
GUIDANCE CONSENSUS SHOWS THE DEVELOPMENT OF A CONVECTIVE LOW IN
THE WESTERN CARIBBEAN SOMETIME DURING THE MEDIUM RANGE
PERIOD...BAROCLINICALLY INITIATED BY AN UPPER TROUGH NEAR FLORIDA.
MID-UPPER LEVEL TROUGHING IS FORECAST TO PERSIST NEAR FLORIDA
THROUGH THE PERIOD...INDICATING WET CONDITIONS FOR SOUTHERN AND
EASTERN PENINSULA THROUGH THE FORESEEABLE FUTURE. IT MY BE A
SIMILAR SITUATION TO THE PATTERN SUFFERED BY THE SUNSHINE STATE
THROUGHOUT THE LATTER TWO-THIRDS OF MAY. FOR NOW...AFTER
COORDINATION WITH TPC...WE HAVE INDICATED A WEAK SURFACE LOW
DRIFTING GENERNALLY N ALONG 83W E OF THE YUCATAN PENINSULA MUCH OF
THE PERIOD.
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agreed wx blog....how can we not look or blog about it? :) but cane whisperer is right about the history....(he beat me to it so he gets all the cred) zebras rarley change their stripes.
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Quoting hurricane23:


Hey, sure no probs heres the link to my model page were you can get a variety of models.VIEW HERE and then HERE for the GFS.

thanks
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Quoting weatherwatcher12:

Can you please send me the link to the gfs


Hey, sure no probs heres the link to my model page were you can get a variety of models.VIEW HERE and then HERE for the GFS.
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back to stealth mode
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Quoting chsweatherintern2009:


I wasn't saying you or anybody in specific.I just know how thing get when people start to depend on the models. I just know how people get. they cry wolf. that is all I was saying hope i did not offend anyone
those here for a bit know that models can and will change in any depiction of a storm this is the pre refining process to give idea as to when where how much and where it ends up is still way out

at this time because models are showing some type of possible dev it should be watch in further runs to see if it maintains this dev and by sunday should start to get somnething to see showing up then we will know better til then wait watch see nothing more
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Major rain maker in the making then for Florida, better cut your grass extra low, you wont be mowing for a while
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I wouldn't mind a tropical storm in South Florida. If this was August-Oct, I'd be a little wary, but right now I actually think it would be fun.
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Classic set-up though
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Quoting Buhdog:
if the storm does come to fruition then we are looking at it coming up on the west side of fl....climatological reasoning being the reason.


Possibly...but I'd rather look at current conditions than climatology.
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Quoting hurricane23:
I think its unlikely what ever developes makes into the gulf as the weakness is towards florida.A track north and then northeastward seems like a good bet.Nothing to get worked up about if anything some deep tropical moisture will move north into parts of southern florida.


agreed
Member Since: July 24, 2005 Posts: 407 Comments: 19076
With steering,especially in Early Season,and LAte season..one has to Look Upstream in time across the CONUS as the Continental Features can Guide these systems as well..and usually do.

One has to develop a feel for the CONUS future as well as any Lower Latitude Entity...thru time
Member Since: July 3, 2005 Posts: 420 Comments: 127536
It could be another stupid swirl that goes where it wants
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Quoting hurricane23:
Strong ts/minimal cane


Can you please send me the link to the gfs
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I think its unlikely what ever developes makes into the gulf as the weakness is towards florida.A track north and then northeastward seems like a good bet.Nothing to get worked up about if anything some deep tropical moisture will move north into parts of southern florida.
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If whatever forms and if it even does and its weak its going more west, if stronger it goes north
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341. IKE
Quoting sporteguy03:
Ike,
ECMWF??


LOL...I was at the store. Shows almost zilch.
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Quoting Orcasystems:


Since you are talking from an experienced background... GFS possible, or do you think its out of touch with reality?


The GFS is showing the full potential of any disturbance under the forecasted conditions. Ido not think the model is farfetch just showing one possibility. The other possibility is that it won't develop or develop but not that strong.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
if the storm does come to fruition then we are looking at it coming up on the west side of fl....climatological reasoning being the reason.
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GFS - NCEP's Global Forecast System

The numerical model used for NCEP's global data assimilation system and for the aviation (AVN) and medium-range forecasts (MRF) is the global spectral model, now known as the Global Forecast System (GFS). As one might guess from its name, the "aviation model" was not specifically developed to predict hurricane motion or intensity. Rather, one of the primary uses of the GFS is to produce forecasts for aviation guidance worldwide. The GFS model is run four times each day at the primary and intermediate synoptic times (0000, 0600, 1200 and 1800 UTC) with a wait of 2.75 hr for data arrival. Forecasts are made out to Day 16.

The GFS is a baroclinic-dynamical model. Like the GHM, the model is a primitive equation model which predicts winds, temperature, surface pressure, humidity, and precipitation. The prediction equations include the divergence and vorticity equations, the hydrostatic equation, the thermodynamic equation, a mass continuity equation, and a conservation equation for water vapor.

The GFS differs from the GFDL Hurricane Model (GHM) model in that it has a global domain, and the fields within the model are represented by a set of mathematical (sine and cosine) functions rather than values at discreet grid points. The forecast equations are solved for the coefficients of the mathematical functions.

The GFS currently is configured to handle 382 triagular waves across the globe (comparable resolution to a grid point model with a grid spacing of 37 km) and has 64 vertical levels. For integrations between 7 1/2 and 16 days the horizontal resolution is reduced to 190 triangular waves.

In July, 2000, a numerical scheme was implemented to change how tropical cyclone vorticies are initialized in the global spectral model (Technical Procedure Bulletin). In the past, bogus observations based on the National Hurricane Center's estimates of storm location, intensity and size were input to the model's analysis scheme. This has been replaced by a procedure that relocates the vortex in the "first guess" field (the forecast from the previous run of the model) to the correct location.

The relocation procedure takes the model guess field and moves the hurricane vortex to the correct location before the model's analysis is completed. The steps can be briefly summarized as:

1. Use a spectral filter to separate the total wind field into Basic and Disturbance fields. (Long waves predominate in the Basic wind field while short waves predominate in the Disturbance wind field.)
2. Locate the hurricane vortex center in the Disturbance wind field,
3. Separate the hurricane model's vortex from the non-hurricane component in the Disturbance wind field,
4. Combine the Basic wind field and non-hurricane component of the Disturbance wind field into the Environmental wind field.
5. Move the extracted hurricane vortex to the NHC official position.
6. If the vortex is too weak in the guess field, add bogus observations to the model analysis.
7. The data assimilation scheme uses the revised guess field and all available observations to produce the final analysis for input to the forecast model.

This animated GIF Vortex replacement procedure flow chart depicts the vortex relocation procedure in a flow-chart format.



The vortex is not relocated if the center of the hurricane is over a major land mass or if the topography in the filtered domain is greater than 500 m in elevation. When the procedure was tested in retrospect on the 1999 hurricane season forecasts, the average track forecasts improved by approximately 30% over that of the operational AVN model. The skill of the AVN track forecasts during the 2000 Atlantic season were significantly better than those of previous years. Skill of AVN track forecasts for 1995-2000

In May, 2001, momentum mixing was included in GFS model's cumulus parameterization scheme. Tests showed this reduces tropical storm false alarm forecasts. Additional changes made to the model at that time were expected to improve the skill in tropical circulation forecasts at all time ranges.


In July, 2006, the vertical coordinate of the GFS was changed from terrain following sigma to a hybrid sigma-pressure coordinate system. The hybrid coordinate is being adopting by modeling centers around the globe and provides improved performance in upper troposphere and stratosphere. Retrospective runs made of some 2005 hurricanes suggest the forecast track skill will not change, while forecast strength may be better than before for hurricanes. Reference: Kanamitsu, M., 1989: Description of the NMC global data assimilation and forecast system. Wea. Forecasting, 4, 335-342.
Member Since: July 3, 2005 Posts: 420 Comments: 127536
Quoting hurricane23:
NWS Miami....

EXTENDED FORECAST...
THE GFS MODEL STILL TRIES TO DEVELOP A LOW IN THE CARIBBEAN SEA
EARLY NEXT WEEK AND MOVING IT NORTHWARD TO THE CENTRAL BAHAMA
ISLANDS BY END OF NEXT WEEK...WHILE THE ECMWF AND NOGAPS KEEP THE
LOW DOWN INTO THE WESTERN CARIBBEAN SEA WITH THE RIDGE OF HIGH
PRESSURE OVER SOUTH FLORIDA. AT THIS TIME WILL CONTINUE WITH THE
ECMWF AND THE NOGAPS MODEL...AS THE GFS LOOKS LIKE IT IS OVERDOING
THE DEEPENING OF TROUGH OF LOW PRESSURE NEXT WEEK PULLING THE LOW
NORTHEAST. SO WILL CONTINUE WITH THE SCATTERED POPS OVER THE CWA
WITH THE HIGHEST POPS OVER THE WEST COAST METRO AREAS FOR MOST OF
NEXT WEEK. BUT WILL CONTINUE TO MONITOR THE LATEST MODELS FOR THE
DEVELOPMENT AND POSITION OF THE LOW DURING NEXT WEEK.


Why wouldnt this high shift it more towards the yucatan if they say high pressure is to sit over Florida??
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i was not trying to offend anyone
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Rather tranquil day in Palm Beach County today in light of the 80% chance of rain. Better get a move on in a big way to hit those numbers.
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Quoting Orcasystems:


I don't see any hype going on? If anything... this is one of the more sane conversation I have seen on here?


I wasn't saying you or anybody in specific.I just know how thing get when people start to depend on the models. I just know how people get. they cry wolf. that is all I was saying hope i did not offend anyone
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Quoting chsweatherintern2009:
and here we go again with all the hyping. Before you go and start freaking out. Let the thing develop. The GFS always hypes. if you want to hype got to accuhype. not here


Who is hyping?
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Ahh, accuweather, I have heard of them from old folklore...
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surface / isotacks/ wind barbs/ streamlines
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AN OVERVIEW OF NHC PREDICTION MODELS


Bernard N. Meisner
Scientific Services Division
National Weather Service Southern Region

Introduction


Storm Track Guidance Models
HURRAN | CLIPER | NHC98 | BAM | LBAR | GHM (GFDL) | GFS (formerly AVN) | NOGAPS | GUNS, GUNA and CONU Ensembles
Relative Skill of the Statistical | Numerical Guidance Models

Storm Intensity Guidance Models
SHIFOR | SHIPS | GHM (GFDL)
Relative Skill of the Intensity Guidance Models

Forecast Verification

Storm Surge Guidance Model
SLOSH
Member Since: July 3, 2005 Posts: 420 Comments: 127536
Quoting chsweatherintern2009:
and here we go again with all the hyping. Before you go and start freaking out. Let the thing develop. The GFS always hypes. if you want to hype got to accuhype. not here


I don't see any hype going on? If anything... this is one of the more sane conversation I have seen on here?
Member Since: October 1, 2007 Posts: 81 Comments: 26511

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About

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