10 replies to this topic

[Somerset Squall]

Invest 99E becomes the seasons seventh tropical depression. NHC discussion:

TROPICAL DEPRESSION SEVEN-E DISCUSSION NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP072010
800 PM PDT THU AUG 05 2010

CONVENTIONAL AND MICROWAVE SATELLITE DATA SHOW THAT THE SMALL LOW
PRESSURE AREA OFF THE SOUTHERN COAST OF MEXICO HAS BECOME BETTER
DEFINED AND HAS ACQUIRED ENOUGH ORGANIZATION TO BE DECLARED A
TROPICAL CYCLONE. THE LATEST DVORAK T-NUMBERS FROM SAB AND TAFB
WERE 2.5...WHICH SUPPORT TROPICAL STORM STRENGTH. HOWEVER...THE
CONVECTIVE TOPS HAVE WARMED SINCE 0000 UTC...SO THE INITIAL
INTENSITY IS SET AT A PERHAPS CONSERVATIVE 30 KT.

THE INITIAL MOTION ESTIMATE IS 290/9. THE DEPRESSION IS LOCATED TO
THE SOUTH OF A MID- TO UPPER-LEVEL RIDGE OVER THE SOUTH-CENTRAL
UNITED STATES AND NORTHERN MEXICO. THIS SHOULD ALLOW THE
DEPRESSION TO MOVE IN A GENERAL WEST-NORTHWESTWARD DIRECTION DURING
THE NEXT COUPLE OF DAYS. THE GLOBAL MODELS DID NOT INITIALIZE THE
SMALL CYCLONE VERY WELL AND MANY OF THEM SHOW THE CYCLONE
INTERACTING WITH ITCZ DISTURBANCES TO THE SOUTH OF THE DEPRESSION.
THIS RESULTS IN MANY OF THE GLOBAL MODELS PREDICTING A SLOWER AND
MORE ERRATIC TRACK DURING THE NEXT FEW DAYS. THIS SCENARIO SEEMS
UNREALISTIC AT THIS TIME. GIVEN THE STRONG RIDGE TO THE
NORTH...THE OFFICIAL FORECAST SHOWS A WEST-NORTHWEST TRACK THAT
IS IN BEST AGREEMENT WITH THE BAM MEDIUM AND HWRF MODELS THROUGH 72
HOURS. AFTER THAT TIME...THE CYCLONE SHOULD BE APPROACHING A
WEAKNESS IN THE RIDGE WEST OF THE BAJA PENINSULA WHICH WILL LIKELY
CAUSE THE CYCLONE TO DECELERATE. DUE TO THE UNUSUALLY LARGE SPREAD
IN THE GUIDANCE THE CONFIDENCE IN THE TRACK FORECAST IS LOWER THAN
NORMAL.

UPPER-LEVEL WINDS ARE FORECAST TO REMAIN CONDUCIVE FOR
INTENSIFICATION DURING THE NEXT 2-3 DAYS. THE OFFICIAL FORECAST
CALLS FOR STEADY STRENGTHENING THROUGH 48 HOURS AND THIS IS AT THE
UPPER-END OF THE INTENSITY GUIDANCE. AFTER 72 HOURS...THE CYCLONE
IS EXPECTED TO BEGIN MOVING OVER COOLER WATER WHICH SHOULD INDUCE
WEAKENING.


FORECAST POSITIONS AND MAX WINDS

INITIAL 06/0300Z 16.0N 102.1W 30 KT
12HR VT 06/1200Z 16.4N 103.5W 40 KT
24HR VT 07/0000Z 17.0N 105.2W 50 KT
36HR VT 07/1200Z 17.7N 106.9W 55 KT
48HR VT 08/0000Z 18.5N 108.5W 60 KT
72HR VT 09/0000Z 19.7N 110.8W 60 KT
96HR VT 10/0000Z 20.7N 113.0W 45 KT
120HR VT 11/0000Z 21.5N 115.0W 30 KT

$$
FORECASTER BROWN

[cookie]

At long last. this system has been looking like it for was going to become a TD for a few days.

Edited by cookie, 06 August 2010 - 17:41 .

[Somerset Squall]

Looking more and more like a tropical storm on satellite imagery, banding features certainly becoming evident.

Attached Thumbnails

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Edited by Somerset Squall, 06 August 2010 - 17:59 .

[cookie]

we now have Estelle

[Somerset Squall]

Estelle strengthened overnight and has held a steady intensity of 45kts today. An intense area of convection is persisting over the LLC, but banding is practically non-existant. Estelle has another 24hrs to stengthen, before waters cool on the west-northwesterly track. At this time, shear is also progged to increase which will likely kill Estelle.

Estelle is moving away from the coast of Mexico, so earlier heavy rains have eased off now. Estelle is not expected to be any further threat to land.

[Somerset Squall]

Estelle has intensified further to 50kts, with pressure down to 998mb. A solid CDO feature is evident with increased banding. Estelle still has time to strengthen a little more before cool waters and high shear take over; NHC are predicting a 55kt peak though Estelle may find enough time to strengthen a little more than this due to it's small size.

[Somerset Squall]

Estelle has shrunk and further intensified. Hints of an eye have been seen, and intensity has increased to 55kts. Such a small cyclone could rapidly spin down however, as cooler waters and high shear await the storm in about 12hrs time. Until then, Estelle could strengthen a little more, and as it is such a small system, a hurricane is not impossible.

[Somerset Squall]

Estelle has moved into cooler waters and the effects have really taken their toll quickly on the small storm. Intensity has been reduced to 40kts, and the rate the convection is subsiding, Estelle may not be long for this world. NHC forecast degeneration into a remnant low by 36 hours time, but this could occur sooner.

[cookie]

she's just had a very lethal dose of shear

[Somerset Squall]

Estelle has been battling high shear and cooler waters for the last 24hrs and has now weakened to a 30kt tropical depression. A few isolated cells of convection remain near the centre, but Estelle's LLC is practically entirely exposed. A mass of convection resides east of the centre but this convection is attached to a seperate developing tropical low. Continued shear and cool sea temps should force Estelle to de-generate into a remnant low within the next 24hrs. Estelle's remnants will then get dragged southeastwards towards the complex low to the south and east. There is a small, but interesting possibility thereafter. As Estelle's remnant low gets dragged southeastwards it will move over much warmer waters and low shear, which COULD allow re-developement, IF the remnants can remain seperate or become dominant from the low to the east. This scenario appears unlikely as the new low will likely dominate Estelle.

[Somerset Squall]

Estelle degenerated into a remnant low yeasterday and has been drawn into a much larger disturbance to the east. Regeneration is not expected.