Extratropical Irene Advisories

[Wnghs2007]

I'll call it - time of death 10:24AM CST. We will miss you #9, you supplied us with 112,684 posts and we thank you for that.

TD 9 is no where near dead, it may be an exposed circulation but that does not make it dead. It will redevelop thunderstorms and it will survive.

[Steve H.]

After its NW jaunt, it seems back on a more westerly course now, and is beginning to tighten up. I always get caught in the same trap. Patience or lack thereof.

[deltadog03]

ok, well maybe it won't reform a new LLC...but, yes, it does appear to moving W attm...

[cycloneye]

Ok good replies but I would want this thread to be more clear to then have the advisories posted.You can replie at the TD#9 threads now posted.

[Ivanhater]

...Tropical depression continues to struggle for survival...

at 5 PM AST...2100z...the poorly defined center of Tropical
Depression Nine was located near latitude 17.0 north...longitude
39.1 west or about 990 miles...1590 km...west of the southernmost
Cape Verde Islands.

The depression is moving toward the west-northwest near 16 mph
...26 km/hr...and this motion is expected to continue during the
next 24 hours.

Maximum sustained winds are near 30 mph... 45 km/hr...with higher
gusts.
Little change in strength is forecast during the next 24 hours.

Estimated minimum central pressure is 1010 mb...29.83 inches.

Repeating the 5 PM AST position...17.0 N... 39.1 W. Movement
toward...west-northwest near 16 mph. Maximum sustained winds... 30
mph. Minimum central pressure...1010 mb.

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

Forecaster Avila

[Ivanhater]

the depression continues to have a vigorous low-level circulation.
Some convective curved bands are trying to develop to the south and
west of the center where the SSTs are a little bit higher. It is
estimated that the maximum winds are 25 knots. The evolution of a
large mid to upper level low currently located to the north of the
depression will be crucial for both the intensity and track
forecasts. If the low moves as far south as shown by the GFS...it
could induce wind shear and also a northerly component of motion to
the depression...resulting in weakening. However...if the
depression passes south of the low...the environment could be less
hostile..and the ocean is warmer there.

Because the depresion does not have deep convection at this time and
is a shallow system...it is moving toward the west-northwest at
14-16 knots steered by the low-level flow. The official forecast
calls for a west-northwest track...with a gradual decrease in
forward speed...and a modest strenghtening beyond 3 days. This
forecast is highly uncertain since there is also a strong
possibility that the depression will not survive. The official
forecast is in the middle the guidance envelope. The northernmost
track is the GFS and the southernmost is the UK model.

Forecaster Avila


forecast positions and Max winds

initial 05/2100z 17.0n 39.1w 25 kt
12hr VT 06/0600z 18.0n 41.0w 25 kt
24hr VT 06/1800z 19.0n 43.5w 25 kt
36hr VT 07/0600z 20.0n 45.5w 30 kt
48hr VT 07/1800z 21.5n 48.0w 30 kt
72hr VT 08/1800z 23.0n 51.0w 35 kt
96hr VT 09/1800z 25.0n 54.0w 40 kt
120hr VT 10/1800z 28.0n 56.0w 45 kt

[cycloneye]

[WeatherEmperor]

hmm. a little bit left or south of the previous forecast track.

<RICKY>

[dwg71]

hmm. a little bit left or south of the previous forecast track.

<RICKY>

very little.

[Brent]

I doubt it even survives...

[cycloneye]

Ok locked until next advisorie.

[cycloneye]

TROPICAL DEPRESSION NINE ADVISORY NUMBER 6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM AST FRI AUG 05 2005

...POORLY ORGANIZED TROPICAL DEPRESSION MOVING WEST-NORTHWESTWARD
ACROSS THE TROPICAL ATLANTIC...

AT 11 PM AST...0300Z...THE CENTER OF TROPICAL DEPRESSION NINE WAS
LOCATED NEAR LATITUDE 17.6 NORTH...LONGITUDE 40.6 WEST OR ABOUT
1090 MILES...1755 KM...WEST-NORTHWEST OF THE SOUTHERNMOST CAPE
VERDE ISLANDS.

THE DEPRESSION IS MOVING TOWARD THE WEST-NORTHWEST NEAR 20 MPH
...32 KM/HR...AND GENERAL THIS MOTION IS EXPECTED TO CONTINUE WITH A
DECREASE IN FORWARD SPEED ON SATURDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 30 MPH... 45 KM/HR...WITH HIGHER
GUSTS. SATELLITE IMAGERY INDICATES THAT THERE IS MINIMAL
THUNDERSTORM ACTIVITY ASSOCIATED WITH THE DEPRESSION AT THIS
TIME...AND LITTLE CHANGE IN STRENGTH IS FORECAST DURING THE NEXT 24
HOURS.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1010 MB...29.83 INCHES.

REPEATING THE 11 PM AST POSITION...17.6 N... 40.6 W. MOVEMENT
TOWARD...WEST-NORTHWEST NEAR 20 MPH. MAXIMUM SUSTAINED
WINDS... 30 MPH. MINIMUM CENTRAL PRESSURE...1010 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL
HURRICANE CENTER AT 5 AM AST.

FORECASTER BEVEN


$$

[cycloneye]

TROPICAL DEPRESSION NINE DISCUSSION NUMBER 6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT FRI AUG 05 2005

TROPICAL DEPRESSION NINE HAS A LARGE AND WELL-DEFINED SWIRL OF LOW
CLOUDS THIS EVENING...BUT THERE IS NO ORGANIZED CONVECTION NEAR THE
CENTER AT THIS TIME. THE CYCLONE IS OVER 26C-27C SEA SURFACE
TEMPERATURES...AND THE WEST-NORTHWESTWARD MOTION HAS TAKEN IT INTO
AN AREA OF WESTERLY VERTICAL SHEAR. THIS COMBINATION HAS
INTERRUPTED DEVELOPMENT. THE INITIAL INTENSITY IS REMAINS 25 KT
BASED ON SATELLITE INTENSITY ESTIMATES...ALONG WITH QUIKSCAT AND
SSM/I WINDS.

THE INITIAL MOTION IS 295/17. THE DEPRESSION IS SOUTH OF A LOW/
MID-LEVEL RIDGE OVER THE EASTERN ATLANTIC. OBSERVATIONS AND
LARGE-SCALE MODEL ANALYSES SHOW A WEAKNESS IN THIS RIDGE BETWEEN
50W-60W PARTLY ASSOCIATED WITH TROPICAL STORM HARVEY...AND THIS
WEAKNESS WILL NOT COMPLETELY FILL DURING THE NEXT FIVE DAYS. IN
RESPONSE...THE CYCLONE SHOULD MOVE GENERALLY WEST-NORTHWESTWARD
WITH SOME SLOWING FOR ABOUT 72 HR...AND THEN POSSIBLY TURN
NORTHWESTWARD. THE TRACK FORECAST GUIDANCE AGREES ON THE FIRST 2-3
DAYS OF MOTION AND THEN DIVERGES. THE UKMET AND THE BAM MODELS
CALL FOR A CONTINUED WEST-NORTHWESTWARD MOTION AT 96-120 HR...WHILE
THE NOGAPS...LBAR...AND GFS ENSEMBLE MEAN CALL FOR A TURN TOWARD
THE NORTH. THE OFFICIAL FORECAST WILL COMPROMISE BETWEEN THESE
EXTREMES...CALLING FOR A GRADUAL NORTHWESTWARD TURN IN BEST
AGREEMENT WITH THE CONSENSUS MODEL CONU. THE FORECAST AFTER 72 HR
IS ALSO SLOWER THAN EARLIER IN LIGHT OF THE GUIDANCE SPREAD.

WATER VAPOR IMAGERY SHOWS A STRONG UPPER-LEVEL LOW NEAR 27N42W WITH
A TROUGH EXTENDING TO NEAR 19N44W. THIS SYSTEM HAS CREATED
WESTERLY UPPER-LEVEL FLOW OVER THE DEPRESSION. LARGE-SCALE MODELS
SUGGEST A SHEARING ENVIRONMENT COULD CONTINUE FOR 2-3 DAYS AS A
SERIES OF UPPER-LEVEL SHORTWAVE TROUGHS PASS NEAR OR NORTH OF THE
DEPRESSION. THE SHIPS MODEL SLOWLY STRENGTHENS THE SYSTEM DESPITE
THE SHEAR AS IT MOVES GRADUALLY OVER WARMER SEA SURFACE
TEMPERATURES...AND THE INTENSITY FORECAST FOLLOWS THAT GUIDANCE.
HOWEVER...THERE IS A CHANCE THAT THE SYSTEM COULD DISSIPATE OR
DEGENERATE INTO A LOW PRESSURE AREA BEFORE CONDITIONS BECOME MORE
FAVORABLE....AS FORECAST BY THE GFDL AND GFS MODELS.

FORECASTER BEVEN


FORECAST POSITIONS AND MAX WINDS

INITIAL 06/0300Z 17.6N 40.6W 25 KT
12HR VT 06/1200Z 18.5N 42.6W 25 KT
24HR VT 07/0000Z 19.6N 44.9W 25 KT
36HR VT 07/1200Z 20.6N 46.9W 30 KT
48HR VT 08/0000Z 21.7N 49.0W 30 KT
72HR VT 09/0000Z 23.5N 52.5W 35 KT
96HR VT 10/0000Z 25.0N 55.0W 40 KT
120HR VT 11/0000Z 27.5N 56.5W 45 KT

[cycloneye]

[Thunder44]

Tropical Depression Nine Advisory Number 7


Statement as of 5:00 am AST on August 06, 2005


...Depression becoming a little better organized over the
open tropical Atlantic...

at 5 am AST...0900z...the center of Tropical Depression Nine was
located near latitude 17.7 north... longitude 41.7 west or about
1405 miles...2265 km... east of the northern Leeward Islands.

The depression 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 35 mph... 55 km/hr...with higher
gusts. Slight strengthening is forecast during the next 24 hours...
and the depression could become a tropical storm by Sunday.

The estimated minimum central pressure is 1008 mb...29.77 inches.

Repeating the 5 am AST position...17.7 N... 41.7 W. Movement
toward...west-northwest near 15 mph. Maximum sustained
winds... 35 mph. Minimum central pressure...1008 mb.

The next advisory will be issued by the National Hurricane Center
at 11 am AST.

Forecaster Stewart

[Thunder44]

Tropical Depression Nine Discussion Number 7


Statement as of 5:00 am EDT on August 06, 2005



TD-9 remains a large and well-defined circulation...and the inner
core wind field has actually improved considerably since this time
yesterday with no multiple circulations apparent in nightime
visible imagery. The intensity is being increased to 30 kt based on
the tighter inner circulation...two consecutive Quikscat overpasses
indicating numerous 30-kt unflagged wind vectors in the northeast
quadrant...and a CIMSS AMSU pressure estimate of 1006.5mb ...equal
to about 33 kt. Convection has been recently been trying to develop
into a curved band in the eastern semicircle about 120 nmi away
from the center...which further suggest improved organization.

The initial motion is 285/13. The depression has slowed and turned
more westward now that the cyclone has moved west of an upper-level
trough located to the north. The forecast track is problematic in
that it is directly related to the intensity...and therefore...the
vertical depth of cyclone. Upper-level westerly winds are expected
to continue across the system for at least the next 36-48 hours.
These unfavorable shear conditions combined with an abundance of
mid-level dry air should keep convective organization and vertical
development of the cyclone to a minimum during that time. This
should allow the system to be steered more westward by the
low-level flow. By 72 hours...the cyclone will be over warmer water
and more steady intensification and deepening of the vertical
circulation should occur...which should allow the cyclone to be
steered slowly northwestward by the deep-layer flow toward an
expected weakness in the subtropical ridge between 55w-60w
longitude. However...if the storm moves more westward and stays
below 20n latitude through 72 hours...then it may never feel the
weakness in the ridge and not turn northwestward. Since the global
models are already too far to the north or right of the current
position and motion...the official track was shifted to the left of
the previous forecast track and is close to the NHC model consensus
through 72 hours and then a little left of the consensus after
that...but not nearly as far left or south as the UKMET model.

The previously mentioned inhibiting factors are not expected to
abate for at least 48 hours. The official intensity forecast is
similar to the SHIPS model through 72 hours and then slightly
higher after that since the forecast track is farther south in a
lower shear environment than what the SHIPS model used. However...
if the actual forecast ends up being farther south...then warmer
water and even less vertical shear would allow for more
strengthening than currently indicated.

Forecaster Stewart

forecast positions and Max winds

initial 06/0900z 17.7n 41.7w 30 kt
12hr VT 06/1800z 18.2n 43.8w 30 kt
24hr VT 07/0600z 18.8n 46.4w 35 kt
36hr VT 07/1800z 19.4n 48.6w 35 kt
48hr VT 08/0600z 20.1n 51.0w 40 kt
72hr VT 09/0600z 21.3n 54.0w 40 kt
96hr VT 10/0600z 23.0n 57.0w 45 kt
120hr VT 11/0600z 25.5n 59.5w 55 kt

[ConvergenceZone]

Thunder,
yep, interesting discussion, especially the part talking about the potential weakness in the ridge. From what I gather, if the storm stays weak and doesn't strengthen much, then it will continue westward, otherwise, north-west. I posted this in another thread, but probably should have put it in one of these, oh well, I'll learn

[cycloneye]

061439
TCDAT4
TROPICAL DEPRESSION NINE DISCUSSION NUMBER 8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT SAT AUG 06 2005

THERE HAS BEEN LITTLE CHANGE IN THE OVERALL STRUCTURE OF THE
DEPRESSION THIS MORNING...EXCEPT THAT MULTIPLE SWIRLS HAVE BEEN
APPARENT NEAR THE MEAN CIRCULATION CENTER. THIS MORNING'S QUIKSCAT
PASS MISSED THE DEPRESSION. THE ADVISORY INTENSITY WILL REMAIN 30
KT...IN ACCORD WITH THE PASS FROM LAST NIGHT. CONVECTION NEAR THE
CENTER IS CURRENTLY VERY LIMITED DUE TO WESTERLY SHEAR...DRY
AIR...AND RELATIVELY COOL SSTS. NONE OF THESE CONDITIONS ARE
EXPECTED TO CHANGE MUCH OVER THE NEXT DAY OR SO...HOWEVER...THE
DEPRESSION WILL BE MOVING OVER 28C WATER IN ABOUT 48 HOURS. A
TRACK TO THE SOUTH OF THE OFFICIAL FORECAST WOULD ALSO KEEP THE
SYSTEM AWAY FROM THE WESTERLY SHEAR. THE OFFICIAL FORECAST IS VERY
CLOSE TO THE SHIPS GUIDANCE...ALTHOUGH IT IS WORTH NOTING THAT THE
GFDL GRADUALLY FADES THIS SYSTEM AWAY.

THE INITIAL MOTION IS 285/10...A LITTLE SLOWER THAN BEFORE. THE
TRACK FORECAST REMAINS PROBLEMATIC. A WEAKNESS IN THE 500 MB RIDGE
ASSOCIATED WITH TROPICAL STORM HARVY SHOULD BE NORTH OF THE
DEPRESSION IN ABOUT 48 HOURS. MUCH OF THE GUIDANCE...LED BY THE
NOGAPS...LIFTS THE DEPRESSION INTO THIS WEAKNESS. THE GFS ACTUALLY
SPLITS THE DEPRESSION...TAKING A PIECE NORTHWARD INTO THE WEAKNESS
BUT ALSO CARRYING A WEAK WAVE WEST-NORTHWESTWARD. IT IS HARD TO BE
CONFIDENT AT THIS POINT ABOUT THE LONG-RANGE TRACK FORECAST. IN
THE INTEREST OF CONTINUITY THE OFFICIAL FORECAST IS CLOSE TO THE
PREVIOUS ADVISORY AND NEAR THE DYNAMICAL MODEL CONSENSUS.
HOWEVER...SATELLITE IMAGES OVER THE PAST HOUR OR SO ARE SUGGESTING
THAT THE CIRCULATION CENTER IS BECOMING BETTER DEFINED ABOUT 45 NMI
TO THE NORTH OF MY ADVISORY POSITION. IF THIS TURNS OUT TO BE THE
DOMINANT CENTER...THEN A NORTHWARD ADJUSTMENT OF THE TRACK MAY BE
REQUIRED THIS AFTERNOON.


FORECASTER FRANKLIN


FORECAST POSITIONS AND MAX WINDS

INITIAL 06/1500Z 17.9N 42.3W 30 KT
12HR VT 07/0000Z 18.3N 43.8W 30 KT
24HR VT 07/1200Z 18.9N 46.0W 30 KT
36HR VT 08/0000Z 19.4N 48.0W 30 KT
48HR VT 08/1200Z 20.4N 50.0W 35 KT
72HR VT 09/1200Z 22.0N 53.0W 40 KT
96HR VT 10/1200Z 23.5N 56.0W 45 KT
120HR VT 11/1200Z 25.5N 59.0W 50 KT

[cycloneye]

[wxman57]

I have no idea what the NHC is looking at for a center near 17.9N, the center is approaching 18.5N/42W. However, I disagree that this means a northward track adjustment is needed. Looks like just a continuation of yesterday's 290 deg motion. If the NHC just means shifting the initial track northward, then that's certainly needed.

SATELLITE IMAGES OVER THE PAST HOUR OR SO ARE SUGGESTING
THAT THE CIRCULATION CENTER IS BECOMING BETTER DEFINED ABOUT 45 NMI TO THE NORTH OF MY ADVISORY POSITION. IF THIS TURNS OUT TO BE THE DOMINANT CENTER...THEN A NORTHWARD ADJUSTMENT OF THE TRACK MAY BE REQUIRED THIS AFTERNOON.