CPAC: DARBY - Post-Tropical

[Alyono]

Wonder if the tropopause is a bit cooler than normal

[Kingarabian]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.2.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 18 JUL 2016 Time : 000000 UTC
Lat : 18:17:43 N Lon : 128:33:44 W


CI# /Pressure/ Vmax
4.5 / 979.1mb/ 77.0kt


Final T# Adj T# Raw T#
4.5 5.0 5.0

Estimated radius of max. wind based on IR : 16 km

Center Temp : -21.2C Cloud Region Temp : -53.7C

Scene Type : EYE

TXPZ24 KNES 180016
TCSENP

A. 05E (DARBY)

B. 18/0000Z

C. 18.3N

D. 128.5W

E. ONE/GOES-W

F. T4.5/4.5/W0.5/24HRS

G. IR/EIR/VIS

H. REMARKS...DT=4.5 BASED ON OW EYE EMBEDDED BY DG SURROUNDED YY LG
GRAY SHADE. PT=4.5. MET=4.0. FT IS BASED ON DT.

I. ADDL POSITIONS

NIL


...SCHWARTZ

[Kingarabian]

[Alyono]

looks like nhc is setting the winds to 75 kts

[Kingarabian]

looks like nhc is setting the winds to 75 kts

No reason to. Heavy Dvorak consensus to go >= 80kts. Unless a buoy somewhere confirmed something else.

[Yellow Evan]

Satellite presentation warrants a T4.5 and that's what SAB/TAFB are at.

[Yellow Evan]

----- Current Analysis -----
Date : 18 JUL 2016 Time : 013000 UTC
Lat : 18:18:16 N Lon : 128:50:05 W


CI# /Pressure/ Vmax
4.7 / 975.3mb/ 82.2kt


Final T# Adj T# Raw T#
4.7 4.9 4.9

Estimated radius of max. wind based on IR : 19 km

Center Temp : -14.1C Cloud Region Temp : -52.0C

Scene Type : EYE

[Kingarabian]

NHC keeps it @ 80kts.

ZCZC MIATCDEP5 ALL
TTAA00 KNHC DDHHMM

HURRICANE DARBY DISCUSSION NUMBER 26
NWS NATIONAL HURRICANE CENTER MIAMI FL EP052016
800 PM PDT SUN JUL 17 2016

Darby has not weakened since the last advisory; in fact the
hurricane looks a little more impressive than it did earlier today.
Although central convection has not strengthened appreciably, the
CDO has become more symmetric and the eye a little more distinct.
The current intensity estimate is held at 80 kt which is close to a
consensus of Dvorak estimates from SAB and TAFB, along with ADT
estimates from UW-CIMSS. Darby is over SSTs near 24 deg C and will
be moving over slightly cooler waters overnight. After that, the
cyclone should traverse SSTs near 25 deg C through 48 hours.
Gradual weakening is predicted due to these somewhat cool waters,
and Darby should lose hurricane status in about 24 hours with
additional weakening thereafter. In 72 hours or so, the ocean under
Darby will warm slightly to 25-26 deg C but by that time the
vertical shear, which had been low, is forecast to increase and this
should prevent restrenghtening in the latter part of the forecast
period. The official intensity forecast is close to the latest
model consensus.

Darby continues on a westward track and the initial motion estimate
remains 275/8 kt. There is no reason to change the track forecast
from the previous advisory package. A narrow east-west oriented
mid-level ridge is expected to be maintained to the north of Darby
for the next several days. Late in the period, a mid-level high
builds to the northwest of the tropical cyclone which should cause
a slightly south of west motion. The official forecast lies a
little south of the dynamical model consensus and is a blend of the
latest GFS and ECMWF predictions.

FORECAST POSITIONS AND MAX WINDS

INIT 18/0300Z 18.4N 129.0W 80 KT 90 MPH
12H 18/1200Z 18.6N 130.7W 70 KT 80 MPH
24H 19/0000Z 19.0N 133.0W 60 KT 70 MPH
36H 19/1200Z 19.4N 135.4W 55 KT 65 MPH
48H 20/0000Z 19.7N 137.7W 50 KT 60 MPH
72H 21/0000Z 19.5N 142.3W 45 KT 50 MPH
96H 22/0000Z 18.7N 147.0W 35 KT 40 MPH
120H 23/0000Z 18.0N 151.0W 35 KT 40 MPH

$$
Forecaster Pasch

NNNN

[Alyono]

glad they kept it 80 kts in the end. SHIPS was initialized at 75 kts

[1900hurricane]

Convection is warming quickly now.

[1900hurricane]

I'm not sure I've actually ever seen a warmer CDO average from ADT while still recognizing the eye pattern.

Code: Select all

 UW - CIMSS                     
              ADVANCED DVORAK TECHNIQUE       
                  ADT-Version 8.2.1               
         Tropical Cyclone Intensity Algorithm       

             ----- Current Analysis -----
     Date :  18 JUL 2016    Time :   050000 UTC
      Lat :   18:30:01 N     Lon :  129:16:49 W

     
                CI# /Pressure/ Vmax
                4.9 / 971.3mb/ 87.4kt

     
             Final T#  Adj T#  Raw T#
                4.4     4.0     4.0

 Estimated radius of max. wind based on IR : 32 km

 Center Temp :  +9.0C    Cloud Region Temp : -36.2C

 Scene Type : EYE 

 Positioning Method : SPIRAL ANALYSIS

 Ocean Basin : EAST PACIFIC 
 Dvorak CI > MSLP Conversion Used : CKZ Method 

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

 C/K/Z MSLP Estimate Inputs :
  - Average 34 knot radii :   80km
  - Environmental MSLP    : 1012mb

 Satellite Name :  GOES15
 Satellite Viewing Angle : 22.6 degrees


[Kingarabian]

Dry air all the way.

[cycloneye]

HURRICANE DARBY DISCUSSION NUMBER 27
NWS NATIONAL HURRICANE CENTER MIAMI FL EP052016
200 AM PDT MON JUL 18 2016

Stable air and cool SSTs are taking a toll on Darby. Although the
system still has a well organized circulation and eye feature, deep
convection has been on a steady decline since the previous advisory.
In fact, the cloud tops are now warmer than -50 deg C. The initial
wind speed is lowered to 70 kt, based on a blend of the Final T- and
CI-numbers from TAFB and SAB. Cool water and dry air should
continue to affect Darby during the next few days, which will likely
result in continued weakening. Beyond that time, SSTs are expected
to increase along the forecast track, but the cyclone will also be
moving into an environment of increasing westerly shear. Given these
mixed signals, little change in strength is shown at the end of the
forecast period. The NHC intensity forecast is largely an update of
the previous one and is close to the intensity model consensus.

Darby is moving a 275/09 kt, and is being steered by a narrow
mid-level ridge to its north. A westward to west-northwestward
motion at a slightly faster pace is forecast during the 2 to 3 days
while the ridge remains in place. After that time, a motion slightly
south of due west is predicted when a mid-level high builds to the
northwest of the tropical cyclone. The latest guidance has shifted
a little to the north this cycle, and the NHC official track
forecast has been nudged in that direction. Based on this forecast,
a much weaker Darby could be approaching the Hawaiian Islands at the
end of the period.

An ASCAT-B pass around 0615 UTC was helpful in estimating the wind
radii of Darby.

FORECAST POSITIONS AND MAX WINDS

INIT 18/0900Z 18.5N 130.2W 70 KT 80 MPH
12H 18/1800Z 18.8N 131.8W 60 KT 70 MPH
24H 19/0600Z 19.3N 134.1W 55 KT 65 MPH
36H 19/1800Z 19.8N 136.4W 50 KT 60 MPH
48H 20/0600Z 20.0N 138.7W 45 KT 50 MPH
72H 21/0600Z 19.6N 143.2W 40 KT 45 MPH
96H 22/0600Z 18.6N 148.0W 35 KT 40 MPH
120H 23/0600Z 18.3N 151.8W 35 KT 40 MPH

$$
Forecaster Cangialosi

[Kingarabian]

Looks like Darby is on its way to being post tropical.

[cycloneye]

HURRICANE DARBY DISCUSSION NUMBER 28
NWS NATIONAL HURRICANE CENTER MIAMI FL EP052016
800 AM PDT MON JUL 18 2016

Deep convection associated with Darby continues to diminish this
morning with a couple of thin, fragmented curved bands located just
to the southwest of the center of circulation. The initial
intensity is, therefore, lowered to 65 kt and agrees with a blend
of the subjective and objective satellite intensity estimates.
The cyclone is currently moving over SSTs near 24C, but will soon
be traversing slightly warmer water during the next day or two.
Consequently, there could be some convective banding redevelopment
which could temporarily curtail weakening. After that time, the
global models all indicate an increase in westerly shear which is
expected to influence further weakening through the end of the
period. The NHC intensity forecast reflects gradual weakening and
is slightly above the Decay SHIPS and LGEM models.

The initial motion estimate is 280/9 kt, to the south of a narrow
mid-tropospheric ridge extending along 30N. A generally westward to
west-northwestward motion with a slight increase in forward speed is
forecast during the next 72 hours. Through the remaining portion
of the forecast period, the aforementioned ridge is expected to
briefly strengthen, causing the cyclone to move just a bit south of
due west. The official forecast is again shifted a little
northward and is located between the multi-model consensus and a
blend of the GFS and ECMWF ensemble mean guidance.


FORECAST POSITIONS AND MAX WINDS

INIT 18/1500Z 18.7N 131.1W 65 KT 75 MPH
12H 19/0000Z 19.1N 132.8W 55 KT 65 MPH
24H 19/1200Z 19.7N 135.0W 50 KT 60 MPH
36H 20/0000Z 20.1N 137.3W 45 KT 50 MPH
48H 20/1200Z 20.2N 139.6W 40 KT 45 MPH
72H 21/1200Z 19.6N 144.3W 35 KT 40 MPH
96H 22/1200Z 18.7N 149.0W 35 KT 40 MPH
120H 23/1200Z 18.8N 152.1W 30 KT 35 MPH

$$
Forecaster Roberts

[Alyono]

new MU in agreement with EC, strong TS or a cane near the Big Island

[Alyono]

GFDL now has a strong TS near the islands

[Yellow Evan]

12z ECMWF shifts way east as it has a stronger ridge. As soon as I thought this was a real Hawaii threat.

[Alyono]

looks to be intensifying again

I think we may need a G-IV flight to settle these model flip flops

[Kingarabian]

I want to see better ensemble agreement with the operational models first.