CPAC: TROPICAL DEPRESSION FELICIA (08E)

[CrazyC83]

85 kt might be a bit conservative IMO. I would say 90-95 kt right now with a pressure around 966mb.

[CrazyC83]

and yet the rapid dissipation flag is on? The changes today nearly broke the system, lol

I believe it takes a while after starting a re-strengthening trend to turn that off after a rapid weakening. It goes by middle-term trends.

[Derek Ortt]

nwhhc still has 105 mph, though I was tempted to increase it. I want to see a little persistence first

[srainhoutx]

RECON will be worth watching, that's for sure.

[CrazyC83]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 7.2.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 07 AUG 2009 Time : 213000 UTC
Lat : 18:22:54 N Lon : 136:56:50 W


CI# /Pressure/ Vmax
5.4 / 963.8mb/ 99.6kt


Final T# Adj T# Raw T#
(3hr avg)
5.4 5.8 5.9

Latitude bias adjustment to MSLP : +1.8mb

Estimated radius of max. wind based on IR :N/A km

Center Temp : -19.2C Cloud Region Temp : -64.8C

Scene Type : EYE

Positioning Method : SPIRAL ANALYSIS

Ocean Basin : EAST PACIFIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : 2.2T/6hr
Weakening Flag : OFF
Rapid Dissipation Flag : ON

[clfenwi]

and yet the rapid dissipation flag is on? The changes today nearly broke the system, lol

I believe it takes a while after starting a re-strengthening trend to turn that off after a rapid weakening. It goes by middle-term trends.

Indeed, according to the ADT documentation, it takes six hours of evaluation for the flag to potentially be turned off.

G.) Rapid Weakening Flag
It is commonly observed that tropical cyclones dissipate at a very rapid rate as they move over colder waters. The Dvorak Technique Rule 8 and Rule 9 constrain the rate of dissipation and modify the current Final T# in the calculation of the CI# intensity estimate value. It is believed that these rules constrain the dissipation rate to those that are not realistic for the East Pacific region and do not allow for the rapid dissipation rates commonly observed. In order to alleviate this problem, the Dvorak Technique Weakening Rule 9 (as discussed in Section E above) has been modified to allow the CI# intensity estimate to reflect this commonly observed phenomena.

The Rapid Weakening Flag will relax the application of the original Rule 9 intensity adjustment to the Final T# when determining the CI#. Typically, up to 1.0 T# is added to the current Final T# value to come up with the CI#. In cases where rapid weakening is determined, the additive value is modified to 0.5. To be identified as a possible rapid weakening event, the Adjusted Raw T# values over the previous six hours are evaluated. If the slope of these points is less than -0.5/6 hours the weakening flag is tripped and subsequently observed for an additional six hours. If over the second six hour period the slope does not increase over the threshold, the rapid weakening flag will be turned on and the CI# additive constant will be adjusted from 1.0 to 0.5.

The rapid weakening flag is held on until the slope of the Adjusted T# values over six hours becomes greater than -0.37/6 hours. If this condition is exceeded for a continuous period of six hours, the rapid flag is then turned off and the additive value will return to 1.0.

[hawaiigirl]

felicia is getting closer and closer to me and it doesn't look like it is weakening ....

[masaji79]

I hope Felicia does weakend considerably. My parents live in Hilo on the Big Island which would be one of the first places that would be affected. We had severe flooding back in 2000 from just a regular winter storm.

[cycloneye]

She is getting stronger.

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 7.2.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 07 AUG 2009 Time : 223000 UTC
Lat : 18:26:37 N Lon : 137:08:50 W


CI# /Pressure/ Vmax
5.7 / 957.0mb/107.2kt


Final T# Adj T# Raw T#
(3hr avg)
5.7 5.8 5.8

Latitude bias adjustment to MSLP : +1.8mb

Estimated radius of max. wind based on IR : 9 km

Center Temp : -34.0C Cloud Region Temp : -65.4C

Scene Type : EYE

Positioning Method : SPIRAL ANALYSIS

Ocean Basin : EAST PACIFIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : ON

[I-wall]

What's the latest on the shear forecasts? I keep hearing that shear is supposed to ramp up and tear this apart, but it doesnt seem to be happening.

[cycloneye]

What's the latest on the shear forecasts? I keep hearing that shear is supposed to ramp up and tear this apart, but it doesnt seem to be happening.

In about an hour the new shear forecast will be out so stay tuned.

[CrazyC83]

- CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 7.2.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 07 AUG 2009 Time : 233000 UTC
Lat : 18:36:14 N Lon : 137:20:50 W


CI# /Pressure/ Vmax
5.8 / 954.5mb/109.8kt


Final T# Adj T# Raw T#
(3hr avg)
5.8 5.8 5.8

Latitude bias adjustment to MSLP : +1.7mb

Estimated radius of max. wind based on IR : 11 km

Center Temp : -21.8C Cloud Region Temp : -63.8C

Scene Type : EYE

Positioning Method : SPIRAL ANALYSIS

Ocean Basin : EAST PACIFIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

[CrazyC83]

08/0000 UTC 18.6N 137.4W T4.5/5.0 FELICIA -- East Pacific

It was 4.0/5.0 so a bit of a recovery, but not nearly what the ADT shows. Given the trends, I would split the difference and guess the intensity at 95 kt.

[cycloneye]

90kts at 00 UTC Best Track

EP, 08, 2009080800, , BEST, 0, 186N, 1374W, 90, 970, HU

[HurricaneRobert]

It looks pretty good, but the stratocumulus clousd ahead indicate cool waters.

[cycloneye]

Good news about the shear at the 00 UTC SHIP update.

Code: Select all

EAST PACIFIC SHIPS INTENSITY FORECAST   *
                    *      GOES DATA AVAILABLE                  *
                    *      OHC  DATA AVAILABLE                  *
                    *     FELICIA  EP082009  08/08/09  00 UTC   *

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120


SHEAR (KT)         7     7     7     4     5    12    17    23    25    27    19    23    24


ftp://ftp.tpc.ncep.noaa.gov/atcf/stext/ ... _ships.txt

[wxmann_91]

It looks pretty good, but the stratocumulus clousd ahead indicate cool waters.

There's been a stratocumulus deck ahead for days, which Felicia has dealt with pretty well. Really now it's up to the shear to do its work, as Derek said the MPI is around Cat 3 so cool water alone will not kill this thing.

[islandgirl78]

Any chance Felicia won't take that turn to the west?

This is probably old news, but I just read on honoluluadvertiser.com that the Hurricane Hunters have arrived at Hickam AFB.

[HURAKAN]

Not giving up that easily.

[cyclonic chronic]

wow i had expected to log on this evening to a cat 1. instead its reintensifying to near cat 4, imo. i dont think cooler waters will do it by themselves. the waters arent gonna get that much colder, then get warmer by the HI. islands. if the shear is weaker than predicted lets b glad the hurricane hunters r there. interesting to see what they really find as opposed to satelite interpretations.