Frances Advisories

[Brent]

Hurricane Frances Advisory Number 11

Statement as of 11:00 am AST on August 27, 2004

...Frances strengthens into a category two hurricane...

interests in the northern Lesser Antilles and the northeastern
Caribbean Sea should closely monitor the progress of Frances over
the next several days.

At 11 am AST...1500z...the center of Hurricane Frances was located
near latitude 15.0 north...longitude 49.0 west or about 820 miles
...1320 km...east of the Lesser Antilles.

Frances is moving toward the west-northwest near 10 mph...17 km/hr.
A motion between west-northwest and northwest is expected to occur
for the next 24 hours or so.

Maximum sustained winds are near 105 mph...165 km/hr...with higher
gusts. This makes Frances a category two hurricane on the
Saffir-Simpson hurricane scale. Additional strengthening is
forecast during the next 24 hours...and Frances could become a
category three major hurricane later today.

Hurricane force winds extend outward up to 15 miles... 30 km...
from the center...and tropical storm force winds extend outward up
to 90 miles...150 km.

The estimated minimum central pressure is 970 mb...28.64 inches.
Repeating the 11 am AST position...15.0 N... 49.0 W. Movement
toward...west-northwest near 10 mph. Maximum sustained
winds...105 mph. Minimum central pressure... 970 mb.

For storm information specific to your area...please monitor
products issued by your local weather office.

The next advisory will be issued by the National Hurricane Center
at 5 PM AST.

Forecaster Stewart

[c5Camille]

...Frances strengthens into a category two hurricane...

interests in the northern Lesser Antilles and the northeastern
Caribbean Sea should closely monitor the progress of Frances over
the next several days.

At 11 am AST...1500z...the center of Hurricane Frances was located
near latitude 15.0 north...longitude 49.0 west or about 820 miles
...1320 km...east of the Lesser Antilles.

Frances is moving toward the west-northwest near 10 mph...17 km/hr.
A motion between west-northwest and northwest is expected to occur
for the next 24 hours or so.

Maximum sustained winds are near 105 mph...165 km/hr...with higher
gusts. This makes Frances a category two hurricane on the
Saffir-Simpson hurricane scale. Additional strengthening is
forecast during the next 24 hours...and Frances could become a
category three major hurricane later today.

Hurricane force winds extend outward up to 15 miles... 30 km...
from the center...and tropical storm force winds extend outward up
to 90 miles...150 km.

The estimated minimum central pressure is 970 mb...28.64 inches.
Repeating the 11 am AST position...15.0 N... 49.0 W. Movement
toward...west-northwest near 10 mph. Maximum sustained
winds...105 mph. Minimum central pressure... 970 mb.

For storm information specific to your area...please monitor
products issued by your local weather office.

The next advisory will be issued by the National Hurricane Center
at 5 PM AST.

Forecaster Stewart

[Brent]

Hurricane Frances Discussion Number 11

Statement as of 11:00 am EDT on August 27, 2004

Frances continues to become better organized while strengthening to
90 kt. The initial intensity is supported by a Dvorak satellite
intensity estimate of t5.0...or 90 kt...from TAFB...a satellite
data T-number of 5.0 form AFWA...and 27/1010z UW-CIMSS AMSU
pressure retrieval of 969.8 mb...which equates to about 90 kt. The
outflow remains excellent and also continues to improve.

The motion is now 300/09. Frances remains on track and has begun to
slow down. A northwestward jog may occur...but it is expected to be
short-lived as the weakness in the subtropical ridge to the north
of Frances is forecast to quickly fill in as the shortwave trough
noted in water vapor imagery along 52w longitude continues to zip
along eastward. The NHC model guidance is in strong agreement on a
west-northwest to northwestward track through 48 hours...but then
diverge significantly after that. However...despite the differing
tracks...all of the models agree on high zonal flow with strong
westerlies developing across the northern U.S. And the North
Atlantic after 48hr. Such a strong high-latitude zonal flow pattern
is usually reflected by a strong subtropical ridge to the south
that extends east-west from the Azores to Bermuda and into the
southeastern U.S. My concern is that the ridge may build in faster
than expected and drive Frances more westward sooner than forecast
...Which is what the 06z GFS model is indicating. However...making
such a sudden and sharp 45 degree left-of-track turn at 48 hours is
probably overdoing it some...but out of respect for the consistent
trend in the GFS model the past 24 hours...the forecast track has
been nudged a little more south and westward in 72-120hr.
Frances is expected to remain in a low shear environment and over
increasing SSTs throughout the period...so at least some slow
intensification should occur. The SHIPS model sharply brings down
the intensity to 73 kt after 72 hours due to increasing westerly
shear of 25-30 kt. However...the vertical shear is fictitious and
'self-inflicted' by the GFS/SHIPS model...due to the official
forecast track being about 180 nmi north of the GFS forecast
positions in 72-120h. This puts Frances in the strong westerly flow
in the northern semicircle of a very intense upper-level high that
all the models develop over Frances. The SHIPS model was discounted
and the official intensity forecast leans toward the GFDL solution.

Forecaster Stewart

forecast positions and Max winds

initial 27/1500z 15.0n 49.0w 90 kt
12hr VT 28/0000z 15.8n 50.4w 100 kt
24hr VT 28/1200z 17.0n 52.1w 100 kt
36hr VT 29/0000z 18.0n 53.6w 105 kt
48hr VT 29/1200z 18.9n 55.2w 105 kt
72hr VT 30/1200z 20.2n 58.5w 110 kt
96hr VT 31/1200z 21.0n 62.0w 110 kt
120hr VT 01/1200z 22.0n 67.0w 110 kt

[mf_dolphin]

We could have a CAT 3 by this afternoon at this rate.

[Derek Ortt]

I'm hoping that SE storm develops, I've seen some experimental models and I dont like their output at all. I want a nice 50-65KT storm/cane going into the Carolinas, not causing too many problems, weakening the ridge and allowing Frances to pass out to sea (wishful thinking on my part, I know)

[c5Camille]

Frances continues to become better organized while strengthening to
90 kt. The initial intensity is supported by a Dvorak satellite
intensity estimate of t5.0...or 90 kt...from TAFB...a satellite
data T-number of 5.0 form AFWA...and 27/1010z UW-CIMSS AMSU
pressure retrieval of 969.8 mb...which equates to about 90 kt. The
outflow remains excellent and also continues to improve.

The motion is now 300/09. Frances remains on track and has begun to
slow down. A northwestward jog may occur...but it is expected to be
short-lived as the weakness in the subtropical ridge to the north
of Frances is forecast to quickly fill in as the shortwave trough
noted in water vapor imagery along 52w longitude continues to zip
along eastward. The NHC model guidance is in strong agreement on a
west-northwest to northwestward track through 48 hours...but then
diverge significantly after that. However...despite the differing
tracks...all of the models agree on high zonal flow with strong
westerlies developing across the northern U.S. And the North
Atlantic after 48hr. Such a strong high-latitude zonal flow pattern
is usually reflected by a strong subtropical ridge to the south
that extends east-west from the Azores to Bermuda and into the
southeastern U.S. My concern is that the ridge may build in faster
than expected and drive Frances more westward sooner than forecast
...Which is what the 06z GFS model is indicating. However...making
such a sudden and sharp 45 degree left-of-track turn at 48 hours is
probably overdoing it some...but out of respect for the consistent
trend in the GFS model the past 24 hours...the forecast track has
been nudged a little more south and westward in 72-120hr.
Frances is expected to remain in a low shear environment and over
increasing SSTs throughout the period...so at least some slow
intensification should occur. The SHIPS model sharply brings down
the intensity to 73 kt after 72 hours due to increasing westerly
shear of 25-30 kt. However...the vertical shear is fictitious and
'self-inflicted' by the GFS/SHIPS model...due to the official
forecast track being about 180 nmi north of the GFS forecast
positions in 72-120h. This puts Frances in the strong westerly flow
in the northern semicircle of a very intense upper-level high that
all the models develop over Frances. The SHIPS model was discounted
and the official intensity forecast leans toward the GFDL solution.
Forecaster Stewart

forecast positions and Max winds

initial 27/1500z 15.0n 49.0w 90 kt
12hr VT 28/0000z 15.8n 50.4w 100 kt
24hr VT 28/1200z 17.0n 52.1w 100 kt
36hr VT 29/0000z 18.0n 53.6w 105 kt
48hr VT 29/1200z 18.9n 55.2w 105 kt
72hr VT 30/1200z 20.2n 58.5w 110 kt
96hr VT 31/1200z 21.0n 62.0w 110 kt
120hr VT 01/1200z 22.0n 67.0w 110 kt

[Air Force Met]

stormcenter~

What are your reasons for her turning out to sea?

My reason for the "out to sea" scenario is purely based on the
storms currently location and movement plus historical paths of storms in that same area during this time of the year.

Actually...historical tracks aren't really on your side here. If you look at historical tracks alone, there is a 50/50 chance at a landfall. If you look at the current location and current movement...that goes up to a 70% chance. If you throw in the 3 day forecast position...and given the synopic pattern that is to be there in three days...then that goes up to about 80%.

I have a neat little FEMA program (since I work with them from the military side of the house) that allows me to plot these things out with different scenarios. Pretty cool...but it shows that climo is not a real decisive factor in the path of this sotrm...and when you throw in the current movement and 3 day forecast...climo actually hints more at a landfall than a fish.

[MWatkins]

You know what...Stacy Stewart writes the BEST discussions there at the NHC...no question about it...although Jack Beven does a good job as does Richard Pasch. But Stewart does it right.

MW

[cape_escape]

Looks like it moves somewhat inland around ft. myers... NOT GOOD

Zack, what did you see that makes you think that? God, I hope not! My son, whose 13, heard the news last night about another hurricane, and now wants to head to Ohio!

[Air Force Met]

I would put
my $ on the out sea scenario right now. IMO

http://www.ssd.noaa.gov/PS/TROP/DATA/RT ... -loop.html

I think you would lose some $ if you did. Here's why.

1) As the NHC pointed out yesterday, the ridge that will be to Frances' north next week is going to be pretty flat...and oriented W-E because of the zonal flow north of it. 2) There are NO major short wave troughs forecasted by any global models expected...matter of fact...there are very few minor ones...the pattern is high zonal over the eastern US. 3) The major longwave trof that is digging into the western US next week will serve to only pump the ridge over the east coast next week...so what we see tha globals doing makes sense.

Bottom line...I think you wuold lose your $ because the odds of something appearing in that zonal pattern that is not forecast...and something that is storng enough to turn the pattern from high zonal to low zonal over the central or eastern US...is low.

[Josephine96]

heads up Islands..

[Brent]

You know whYou know what...Stacy Stewart writes the BEST discussions there at the NHC...no question about it...although Jack Beven does a good job as does Richard Pasch. But Stewart does it right.

MW

I agree. His discussions are always the most in-depth and easiest to understand.

[Air Force Met]

From the discussion:

HOWEVER...DESPITE THE DIFFERING
TRACKS...ALL OF THE MODELS AGREE ON HIGH ZONAL FLOW WITH STRONG
WESTERLIES DEVELOPING ACROSS THE NORTHERN U.S. AND THE NORTH
ATLANTIC AFTER 48HR. SUCH A STRONG HIGH-LATITUDE ZONAL FLOW PATTERN
IS USUALLY REFLECTED BY A STRONG SUBTROPICAL RIDGE TO THE SOUTH
THAT EXTENDS EAST-WEST FROM THE AZORES TO BERMUDA AND INTO THE
SOUTHEASTERN U.S.
************************
And this is my point. There is nothing coming down to break open that ridge. All the action is in the western US and high zonal flow will continue through next week. The ridge will only get stronger given the digging trof in the western US.

[cape_escape]

SE Florida seems to have a protective shield that makes hurricanes come close, but deflects them in another direction.

My sister, who lives in Clearater, told me a story about the Indians putting a protective spell on Tampa Bay...Anyone ever heard of it?

[Lowpressure]

I am saying it is a PR threat then a Carolina issue down the road. We need to start looking at what, if any long range troughing is coming down towards the SE coast. After all Labor day is coming. It seems there is always something tropical going on during Labor day.

[Hyperstorm]

Also notice the much slower forward motion of the storm. It has been this slow for hours. That is not good news...

[Fego]

This part:
My concern is that the ridge may build in faster
than expected and drive Frances more westward sooner than forecast
...Which is what the 06z GFS model is indicating. However...making
such a sudden and sharp 45 degree left-of-track turn at 48 hours is
probably overdoing it some...but out of respect for the consistent
trend in the GFS model the past 24 hours...the forecast track has
been nudged a little more south and westward in 72-120hr.""

Here in the Caribbean, we are on alert mode. Any thoughts?..

[paulvogel]

Where are the tampa bay indians????
And please dont say anything about the "seminole hard rock casino"

The fact is, if you have a long enough time for your scenario, all spots along the gom and atlantic coast will see 200 mph winds.

Might take 100s of years!!

[Fego]

In the 11am, NHC says..:
""
My concern is that the ridge may build in faster
than expected and drive Frances more westward sooner than forecast
...Which is what the 06z GFS model is indicating. However...making
such a sudden and sharp 45 degree left-of-track turn at 48 hours is
probably overdoing it some...but out of respect for the consistent
trend in the GFS model the past 24 hours...the forecast track has
been nudged a little more south and westward in 72-120hr..""

So, we still are in alert mode in the Caribbean...

[BlizzardNole]

Noooo! Don't hit Puerto Rico! That place is beautiful. I am going to Isla Verde, PR this December. Can't wait!