Helene main thread 11am

[ringo]

This storm seems to be moving way too fast.

That will slow down intensification and could keep it within the ITCZ longer.

[ROLLTIDE]

.Tropical Storm Helene Discussion Number 9

Statement as of 11:00 am EDT on September 14, 2006



a Quikscat ambiguity analysis from 0802 UTC was helpful in locating
the center which was further south than the previous advisory.
Visible satellite imagery suggests Helene is slowly becoming better
organized with increasing curvature noted in the banding features.
Satellite intensity estimates are 45 kt from TAFB...35 kt from SAB
and AFWA. The initial intensity is increased slightly to 40 kt for
this advisory.
The storm continues to race westward at 275/20 as it currently
remains south of the subtropical ridge. The spread in the track
guidance remains large especially beyond 24 to 36 hours.
As noted in the previous discussion...the models offer two
solutions. The GFS...its ensemble mean...and the GFDL are to the
right and forecast the ridge to the north to weaken quite rapidly
allowing the storm to turn northwestward in about 12 hours. The
UKMET keeps the subtropical ridge and maintains a west-northwest
track longer. In general all of the models decrease the forward
speed by half over the central Atlantic during days 3-5. By that
time the track forecast is quite uncertain since the guidance
envelope is more than 450 miles wide. The new official track
forecast is moved to the left of the previous advisory...and now
in agreement with the model consensus.

The intensification of Helene is likely to be slow initially because
of the currently broad circulation of the cyclone. Convection should
eventually consolidate near the circulation center and allow for
more steady strengthening during the next day or two. SSTs along
the forecast track are forecast to remain 27-28 celsius and the
system is expected to remain in a weak shear environment. Thus
Helene is forecast to become a hurricane by 36 hours. The SHIPS and
GFDL models indicate a peak intensity of 90-95 kt while the FSU
superensemble indicates Helene could become a major hurricane.
The official forecast is lower than all the guidance for the first
day or two given the current slow rate of intensification
thereafter...the forecast is close to the SHIPS and GFDL guidance
and brings Helene to a category two hurricane.

Forecast positions and Max winds

initial 14/1500z 13.4n 36.8w 40 kt
12hr VT 15/0000z 13.8n 39.1w 45 kt
24hr VT 15/1200z 14.8n 42.0w 55 kt
36hr VT 16/0000z 16.2n 44.1w 65 kt
48hr VT 16/1200z 17.5n 46.0w 75 kt
72hr VT 17/1200z 19.5n 49.0w 85 kt
96hr VT 18/1200z 21.5n 51.0w 90 kt
120hr VT 19/1200z 24.5n 53.0w 90 kt

[Alabamaboy]

Here are the latest OFFICIAL model runs as of 14/12Z by the NHC and the latest positions as of 11:00AM AST by the NHC

[LSUtigers87]

Originally Posted by Alabamaboy
Here are the latest OFFICIAL model runs as of 14/12Z by the NHC and the latest positions as of 11:00AM AST by the NHC


Wow, can you say "look out New World!!" The models are everywhere!

.Tropical Storm Helene Discussion Number 9

Statement as of 11:00 am EDT on September 14, 2006



a Quikscat ambiguity analysis from 0802 UTC was helpful in locating
the center which was further south than the previous advisory.
Visible satellite imagery suggests Helene is slowly becoming better
organized with increasing curvature noted in the banding features.
Satellite intensity estimates are 45 kt from TAFB...35 kt from SAB
and AFWA. The initial intensity is increased slightly to 40 kt for
this advisory.
The storm continues to race westward at 275/20 as it currently
remains south of the subtropical ridge. The spread in the track
guidance remains large especially beyond 24 to 36 hours.
As noted in the previous discussion...the models offer two
solutions. The GFS...its ensemble mean...and the GFDL are to the
right and forecast the ridge to the north to weaken quite rapidly
allowing the storm to turn northwestward in about 12 hours. The
UKMET keeps the subtropical ridge and maintains a west-northwest
track longer. In general all of the models decrease the forward
speed by half over the central Atlantic during days 3-5. By that
time the track forecast is quite uncertain since the guidance
envelope is more than 450 miles wide. The new official track
forecast is moved to the left of the previous advisory...and now
in agreement with the model consensus.

The intensification of Helene is likely to be slow initially because
of the currently broad circulation of the cyclone. Convection should
eventually consolidate near the circulation center and allow for
more steady strengthening during the next day or two. SSTs along
the forecast track are forecast to remain 27-28 celsius and the
system is expected to remain in a weak shear environment. Thus
Helene is forecast to become a hurricane by 36 hours. The SHIPS and
GFDL models indicate a peak intensity of 90-95 kt while the FSU
superensemble indicates Helene could become a major hurricane.
The official forecast is lower than all the guidance for the first
day or two given the current slow rate of intensification
thereafter...the forecast is close to the SHIPS and GFDL guidance
and brings Helene to a category two hurricane.

Forecast positions and Max winds

initial 14/1500z 13.4n 36.8w 40 kt
12hr VT 15/0000z 13.8n 39.1w 45 kt
24hr VT 15/1200z 14.8n 42.0w 55 kt
36hr VT 16/0000z 16.2n 44.1w 65 kt
48hr VT 16/1200z 17.5n 46.0w 75 kt
72hr VT 17/1200z 19.5n 49.0w 85 kt
96hr VT 18/1200z 21.5n 51.0w 90 kt
120hr VT 19/1200z 24.5n 53.0w 90 kt

The western bend has gone away now.

[ROLLTIDE]

Tropical Storm Public Advisory
Statement as of 5:00 PM AST on September 14, 2006

...Helene moving slower...remains far from land...
At 500 PM AST...2100z...the center of Tropical Storm Helene waslocated near latitude 14.2 north...longitude 37.6 west or about 885miles...1420 km...west of the southernmost Cape Verde Islands.
Helene is moving toward the west-northwest near 16 mph...26 km/hr...and this general motion is expected to continue during the next24 hours.
Maximum sustained winds are near 45 mph...75 km/hr...with highergusts. Some strengthening is forecast during the next 24 hours.
Tropical storm force winds extend outward up to 105 miles...165 kmfrom the center.
Estimated minimum central pressure is 1003 mb...29.62 inches.
Repeating the 500 PM AST position...14.2 N...37.6 W. Movementtoward...west-northwest near 16 mph. Maximum sustained winds...45mph. Minimum central pressure...1003 mb.
The next advisory will be issued by the National Hurricane Center at1100 PM AST.
$$Forecaster brown/Franklin

[GingerStorm]

This is going to be fun to watch and see where the storm actually goes, seeing as how all the models send it in every which way!!!

[Alabamaboy]

Here are the latest OFFICIAL model runs as of 14/18Z by the NHC and the latest positions as of 5:00PM AST by the NHC

[shellylay81]

If it stays on the southern side of where some of the models are pointing will it have a chance to get near enough to the east coast that it will kick up the surf.. my family is going on a cruise this saturday to the Caribbean..

[WPBWeatherboy]

Looks like a new area of convection for Helene is gonna start popping up. http://www.ssd.noaa.gov/goes/east/catl/rb-l.jpg

You can also enjoy a nice view of Gordon.

[pullenr]

One more time:

http://wind.mit.edu/~btangy/Home/TCGuid.htm

[ROLLTIDE]

Tropical Storm Public Advisory

Statement as of 11:00 PM AST on September 14, 2006


...Helene continuing west-northwestward over the eastern tropical
Atlantic Ocean...

at 1100 PM AST...0300z...the center of Tropical Storm Helene was
located near latitude 14.5 north...longitude 38.9 west or about 970
miles...1560 km...west of the southernmost Cape Verde Islands.

Helene is moving toward the west-northwest near 15 mph...24 km/hr...
and this general motion is expected to continue for the next 24
hours.

Maximum sustained winds are near 45 mph...75 km/hr...with higher
gusts. Slow strengthening is forecast during the next 24 hours.

Tropical storm force winds extend outward up to 105 miles...165 km
from the center.

The estimated minimum central pressure is 1003 mb...29.62 inches.

Repeating the 1100 PM AST position...14.5 N...38.9 W. Movement
toward...west-northwest near 15 mph. Maximum sustained winds...45
mph. Minimum central pressure...1003 mb.

The next advisory will be issued by the National Hurricane Center
at 500 am AST.

$$
Forecaster Stewart



Tropical Storm Helene Discussion Number 11

Statement as of 11:00 PM EDT on September 14, 2006



the initial motion remains 285/13...based primarily on microwave
satellite fix positions. The 18z NHC model guidance has less spread
now than previous advisories...with the GFS and NOGAPS models
having shifted more westward and closer to the UKMET 12z solution.
The new 18z UKMET run is also much slower now and very similar to
the 18z NOGAPS model run. The key player during the forecast cycle
is the mid-level shortwave trough currently over the northeastern
U.S. That is forecast by all of the models to dig southeastward and
cutoff into a low pressure system. However...the UKMET and NOGAPS
models are now weakening the low and lifting it out sooner than the
GFS...ECMWF... GFDL...and Canadian models. Given that the
mid-latitude flow across the northern U.S. And the North Atlantic
is forecast by all the models to be fast zonal flow...less
amplification of the trough seems more reasonable...which should
decrease the effect of any northward steering flow on the wast side
of the trough. The result is that the steering flow should weaken
considerably by 96 and 120 hours as mid-level ridging builds slowly
westward to the north of Helene. The official forecast track is a
little south of the previous track and is close to the GUNA and
CONU model consensus forecast tracks.
Helene has been having a difficult time maintaining central deep
convection for more than a just few hours at a time due to a large
slug of dry air punching into the southern and eastern quadrants of
the cyclone. Since this pattern seems to be unlikely to change any
time soon...the intensity forecast was decreased slightly during
the first 72 hours similar to the SHIPS model. After that... a
slightly faster rate of intensification is forecast as per the GFDL
and FSU models...which seems reasonable since Helene will be moving
over 28c and warmer SSTs and also be underneath a very favorable
upper-level outflow regime.
Forecast positions and Max winds

initial 15/0300z 14.5n 38.9w 40 kt
12hr VT 15/1200z 15.3n 40.8w 45 kt
24hr VT 16/0000z 16.4n 43.2w 50 kt
36hr VT 16/1200z 17.5n 45.2w 60 kt
48hr VT 17/0000z 18.5n 46.7w 70 kt
72hr VT 18/0000z 20.3n 49.4w 80 kt
96hr VT 19/0000z 22.4n 51.9w 90 kt
120hr VT 20/0000z 24.5n 54.0w 90 kt

$$
forecaster Stewart

[Alabamaboy]

Here are the latest OFFICIAL model runs as of 15/00Z by the NHC and the latest positions as of 11:00PM AST by the NHC

[windy]

I keep hearing those say its a fish. Where do you all get your info that Helene is going to be a fish. Is she going to curve out to sea like Florence & Gordon. The track doesn't look like its curving out to sea. I guess it must be too early to tell right now. I keep hearing a bermuda high is the one keeping storms from coming close to land. Is this true or what? anyone know about this.

[HurricaneYaMAMA]

I dont get it. All of the computer models have it moving NW RIGHT NOW. It is moving DUE WEST. And if you look at the cloud flow around it, the Westward motion has extended all the way to the lesser antillies. It looks like the ridge is firm in place and moving more and more west. The TS is getting much better organized and still moving at a nice clip. I don't see a sudden shift to the NW happening now, muchless in the next couple days.

They are all smoking dope on this one. High on something. Not going to happen.

[ROLLTIDE]

Tropical Storm Public Advisory
Statement as of 5:00 am AST on September 15, 2006

...Helene still not yet strengthening...
At 500 am AST...0900z...the center of Tropical Storm Helene waslocated near latitude 15.0 north...longitude 40.3 west or about 1060miles...1710 km...west of the southernmost Cape Verde Islands.
Helene is moving toward the west-northwest near 15 mph...24 km/hr. A continued motion toward the west-northwest with a gradualdecrease in forward speed is expected during the next 24 hours.
Maximum sustained winds are near 45 mph...75 km/hr...with highergusts. Some strengthening is forecast during the next 24 hours.
Tropical storm force winds extend outward up to 105 miles...165 kmfrom the center.
Estimated minimum central pressure is 1003 mb...29.62 inches.
Repeating the 500 am AST position...15.0 N...40.3 W. Movementtoward...west-northwest near 15 mph. Maximum sustained winds...45mph. Minimum central pressure...1003 mb.
The next advisory will be issued by the National Hurricane Center at1100 am AST.
$$Forecaster Knabb

[ROLLTIDE]

Tropical Storm Public Advisory
Statement as of 11:00 am AST on September 15, 2006

...Helene a little stronger...forecast to remain out to sea...
At 1100 am AST...1500z...the center of Tropical Storm Helene waslocated near latitude 15.8 north...longitude 41.4 west or about 1355miles...2180 km...east of the Leeward Islands.
Helene is moving toward the west-northwest near 13 mph...20 km/hr...and this motion is expected to continue during the next day or two.
Maximum sustained winds are near 60 mph...95 km/hr...with highergusts. Some strengthening is forecast during the next 24 hours andHelene could become a hurricane on Saturday.
Tropical storm force winds extend outward up to 105 miles...165 kmfrom the center.
Estimated minimum central pressure is 1000 mb...29.53 inches.
Repeating the 1100 am AST position...15.8 N...41.4 W. Movementtoward...west-northwest near 13 mph. Maximum sustained winds...60mph. Minimum central pressure...1000 mb.
The next advisory will be issued by the National Hurricane Center at500 PM AST.
$$Forecaster Avila


Tropical Storm Helene Discussion Number 13

Statement as of 11:00 am EDT on September 15, 2006



GOES and Meteosat satellite images indicate that the cloud pattern
is better organized and is more typical of a tropical storm. The
convection is more concentrated near the center...and there is a
well-defined cyclonically curved band to the south with numerous
rainbands all around. The outflow is primarily defined to the south
and to the west. In fact...T-numbers have increased and support
intensities of at least 50 knots. I am only going to mention the
well-known parameters that favor intensification...low shear and
warm ocean...and these two are currently present. Therefore...the
official forecast calls for gradual strengthening and Helene could
become a hurricane in about a day.

Helene appears to have slowed down a little bit and is now moving
toward the west-northwest or 300 degrees at 11 knots. Helene is
currently south of a ridge...but is expected to turn northwestward
toward a large trough or weakness which is forecast to cover the
western Atlantic. There is not much more to add to the track
forecast except that there is high confidence since most of the
reliable guidance... GFDL/GFS/UK/ECMWF models and so forth...
unanimously turn the cyclone northwestward and northward over open
water.


Forecast positions and Max winds

initial 15/1500z 15.8n 41.4w 50 kt
12hr VT 16/0000z 16.6n 43.1w 60 kt
24hr VT 16/1200z 17.8n 45.0w 65 kt
36hr VT 17/0000z 18.7n 46.5w 70 kt
48hr VT 17/1200z 19.5n 48.0w 75 kt
72hr VT 18/1200z 21.5n 50.5w 85 kt
96hr VT 19/1200z 23.5n 53.0w 85 kt
120hr VT 20/1200z 26.0n 55.0w 85 kt

$$

[Alabamaboy]

Here are the latest OFFICIAL model runs as of 15/12Z by the NHC and the latest positions as of 11:00AM AST by the NHC

[ROLLTIDE]

Tropical Storm Public Advisory
Statement as of 5:00 PM AST on September 15, 2006

...Helene nearing hurricane strength...poses no threat to land...
at 500 PM AST...2100z...the center of Tropical Storm Helene waslocated near latitude 16.7 north...longitude 42.8 west or about 1255miles...2020 km...east of the Leeward Islands.
Helene is moving toward the west-northwest near 15 mph...24 km/hr...and this motion is expected to continue during the next 24 hours.
Maximum sustained winds have increased to near 70 mph...110km/hr...with higher gusts. Helene could become a hurricane tonightor Saturday.
Tropical storm force winds extend outward up to 115 miles...185 kmfrom the center.
Estimated minimum central pressure is 992 mb...29.29 inches.
Repeating the 500 PM AST position...16.7 N...42.8 W. Movementtoward...west-northwest near 15 mph. Maximum sustained winds...70mph. Minimum central pressure...992 mb.
The next advisory will be issued by the National Hurricane Center at1100 PM AST.
$$Forecaster Avila
Tropical Storm Helene Discussion Number 14
Statement as of 5:00 PM EDT on September 15, 2006

Helene is definitely strengthening at this time and is very nearhurricane status. Satellite images show an impressivecyclonically-curved convective band wrapping around the center. Theoutflow is well-established and is most impressive to the west andsouth of the cyclone. All indications are that Helene willcontinue in a low-shear environment and will be moving over warmerwaters...according to buoy data nearby. There are no other apparentconditions that could halt additional strengthening over the next 2to 3 days.
Helene is moving toward the west-northwest or 300 degrees...back atthe earlier speed of 13 knots...around the periphery of thesubtropical ridge. A strong mid-latitude trough...which is forecastto be over the western Atlantic...will likely erode the ridge.The expected steering pattern will force Helene to gradually turn tothe northwest as indicated in the official forecast. This is thegeneral solution provided by most of the guidance but models varyin how far west they bring Helene depending on each model'sforecast representation of the ridge. Nevertheless...no modelbrings Helene past 60w longitude in five days in the latest morningrun...and in fact...most of them turn the cyclone northward.
Forecast positions and Max winds
initial 15/2100z 16.7n 42.8w 60 kt 12hr VT 16/0600z 17.7n 44.5w 70 kt 24hr VT 16/1800z 18.6n 46.0w 75 kt 36hr VT 17/0600z 19.5n 47.5w 85 kt 48hr VT 17/1800z 20.5n 49.0w 95 kt 72hr VT 18/1800z 22.0n 51.0w 100 kt 96hr VT 19/1800z 24.0n 54.0w 95 kt120hr VT 20/1800z 26.0n 56.5w 90 kt
$$forecaster Avila

[Alabamaboy]

Here are the latest OFFICIAL model runs as of 15/18Z by the NHC and the latest positions as of 5:00PM AST by the NHC

[windy]

The model runs for 9/15 8pm shows the GFDL turning Northward. The NOGAPS towards the caribbean and the other models GFS, UKMET & BAM show it coming toward the EC. Don't all of the models have to show curving out to sea if this is the track shes going to take? educate me here on this.