CPAC: DARBY - Post-Tropical

[Kingarabian]

00z Euro is further west.

[Kingarabian]

00z Euro has landfall + riding the island chain.

[stormwise]

[Kingarabian]

000
WTPA43 PHFO 210912
TCDCP3

TROPICAL STORM DARBY DISCUSSION NUMBER 39
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP052016
1100 PM HST WED JUL 20 2016

Since this afternoon, the satellite cloud pattern around Darby has
become a bit better organized and the area of cold tops has
increased. A series of microwave passes between 03 and 04 UTC
also showed an increase in organization. The latest subjective
Dvorak intensity estimates were 2.5/35 kt from SAB, 3.0/45 kt from
JTWC and 3.5/55 kt from HFO. The initial intensity for this
advisory has been raised to 55 kt.

The center of Darby is not easy to locate on GOES 15 imagery, but
the microwave passes from a few hours ago show that the storm has
continued to track south of west. The track forecast has shifted
very slightly southwest from the previous track over the next 72
hours. The mid-level ridge northwest of Darby will steer the storm
west southwest with a very gradual turn to the west. Beyond 72
hours, Darby is expected to turn rather sharply toward the
northwest as a low aloft in the Gulf of Alaska digs strongly south.
This is a rather unusual track for a tropical cyclone in the central
Pacific, so there is a greater than normal amount of uncertainty to
the forecast. Since Darby continues to track toward the main
Hawaiian Islands it will probably be necessary to issue a
Tropical Storm Watch within the next 12 hours.

Darby will be moving over slightly warmer water the next couple of
days, while vertical wind shear is forecast to increase slightly.
Darby is expected to remain surrounded by rather dry air. Little
change in intensity is expected for the next few days with gradual
weakening beyond that as Darby turns northwest over cooler water
and vertical wind shear increases. The official forecast lies close
to the IVCN consensus.

Interests in the Hawaiian islands should monitor the progress of
Darby. However, it is important not to focus too closely on the
exact track and intensity forecasts because the average track error
72 hours out is near 100 miles, while the average intensity error is
about 15 kt. In addition, the hazards of a tropical cyclone can
extend over a broad area well away from the center.



FORECAST POSITIONS AND MAX WINDS

INIT 21/0900Z 19.3N 143.8W 55 KT 65 MPH
12H 21/1800Z 18.9N 145.7W 55 KT 65 MPH
24H 22/0600Z 18.6N 147.9W 55 KT 65 MPH
36H 22/1800Z 18.5N 150.0W 55 KT 65 MPH
48H 23/0600Z 18.7N 151.6W 55 KT 65 MPH
72H 24/0600Z 19.8N 153.8W 55 KT 65 MPH
96H 25/0600Z 22.3N 155.3W 50 KT 60 MPH
120H 26/0600Z 25.5N 157.5W 40 KT 45 MPH

$$
Forecaster Donaldson

[NDG]

Hawaii has to thank the dry air environment Darby is surrounded by, otherwise it would had made a run to become a hurricane again before affecting Hawaii with warm waters and low shear. IMO.

[Alyono]

this is in no way a 55 kt storm

[stormwise]

If the stitched is correct then storm will eventually track into a lesser hostile environment than atm.

[Yellow Evan]

I wish my parents were this nice.

Code: Select all

                    * EAST PACIFIC SHIPS INTENSITY FORECAST          *
                    * IR SAT DATA AVAILABLE,       OHC AVAILABLE     *
                    *  DARBY       EP052016  07/21/16  12 UTC        *

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    55    54    53    50    49    47    44    42    39    35    28    25    22
V (KT) LAND       55    54    53    50    49    47    44    42    39    35    28    25    22
V (KT) LGEM       55    56    55    54    53    51    48    46    44    42    38    34    31
Storm Type      TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP

SHEAR (KT)         8    11    12    10    11     8     8    10    17    23    30    27    26
SHEAR ADJ (KT)    -2    -2     1     4     2     3     2     0     2     3     0    -4    -5
SHEAR DIR        254   247   249   239   246   257   275   207   216   210   229   220   229
SST (C)         25.9  26.1  26.2  26.3  26.5  26.5  26.5  26.5  26.5  26.2  25.9  25.6  25.1
POT. INT. (KT)   123   125   126   127   128   128   127   127   127   125   122   119   114
200 MB T (C)   -53.0 -53.2 -53.0 -53.0 -53.3 -53.3 -53.7 -53.5 -53.8 -53.9 -54.3 -54.9 -55.1
200 MB VXT (C)   0.4   0.4   0.3   0.2   0.2   0.1   0.4   0.2   0.1   0.0   0.4   0.2   0.3
TH_E DEV (C)       5     5     6     6     6     7     7     7     7     7     6     6     6
700-500 MB RH     40    37    36    34    36    39    42    44    45    45    44    42    40
MODEL VTX (KT)    19    19    18    17    17    18    17    17    16    14    10    10     8
850 MB ENV VOR    58    51    35    29    29    23    13    15     8    15    15     3   -26
200 MB DIV       -15   -11   -19   -28   -12   -27     2    18     7     6    -2    10    -9
700-850 TADV      -1     1     6     2     1     3     4     4    10    16    19    23    21
LAND (KM)       1071   953   835   723   611   414   273   148    83   114   230   344   445
LAT (DEG N)     19.0  18.8  18.6  18.5  18.4  18.5  18.8  19.3  20.1  21.4  23.0  24.6  26.1
LONG(DEG W)    144.6 145.8 146.9 148.0 149.1 151.0 152.3 153.4 154.3 155.1 155.7 156.8 158.3
STM SPEED (KT)    12    11    11    10     9     8     6     6     7     8     9    10     9
HEAT CONTENT       0     0     1     2     6     9     8     7     7     8     2     0     0

  FORECAST TRACK FROM OFCI      INITIAL HEADING/SPEED (DEG/KT):255/ 13      CX,CY: -12/ -2
  T-12 MAX WIND:  50            PRESSURE OF STEERING LEVEL (MB):  717  (MEAN=586)
  GOES IR BRIGHTNESS TEMP. STD DEV.  50-200 KM RAD:  19.5 (MEAN=14.5)
  % GOES IR PIXELS WITH T < -20 C    50-200 KM RAD:  39.0 (MEAN=65.0)
  PRELIM RI PROB (DV .GE. 30 KT IN 24 HR):            0.7

                        INDIVIDUAL CONTRIBUTIONS TO INTENSITY CHANGE
                         6   12   18   24   36   48   60   72   84   96  108  120
                        ----------------------------------------------------------
  SAMPLE MEAN CHANGE     0.   0.   1.   1.   1.   1.   1.   1.   0.  -1.  -1.  -2.
  SST POTENTIAL          0.   1.   1.   1.   2.   1.   1.   1.   1.   1.   0.  -1.
  VERTICAL SHEAR MAG     0.   0.   1.   1.   2.   3.   3.   2.  -1.  -5.  -8. -11.
  VERTICAL SHEAR ADJ     0.   0.   0.   0.  -1.  -1.  -1.  -1.  -1.  -1.   0.   0.
  VERTICAL SHEAR DIR     0.  -1.  -1.  -2.  -3.  -5.  -5.  -6.  -6.  -5.  -4.  -3.
  PERSISTENCE            1.   2.   2.   2.   1.   1.   1.   1.   0.   0.   0.   0.
  200/250 MB TEMP.       0.   0.   0.   0.   1.   1.   2.   2.   3.   3.   3.   3.
  THETA_E EXCESS         0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.
  700-500 MB RH          0.  -1.  -1.  -1.  -2.  -3.  -4.  -5.  -5.  -6.  -6.  -7.
  MODEL VTX TENDENCY     0.   0.  -2.  -2.  -1.  -2.  -3.  -5.  -6. -11. -11. -13.
  850 MB ENV VORTICITY   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   1.
  200 MB DIVERGENCE      0.  -1.  -2.  -2.  -4.  -5.  -5.  -5.  -4.  -4.  -4.  -3.
  850-700 T ADVEC        0.   0.   0.   0.   0.   0.   0.   1.   1.   2.   3.   4.
  ZONAL STORM MOTION     0.   1.   1.   1.   2.   2.   3.   2.   2.   1.   1.   1.
  STEERING LEVEL PRES    0.   0.   1.   1.   1.   2.   2.   2.   2.   3.   3.   3.
  DAYS FROM CLIM. PEAK   0.   0.   0.   0.   0.   0.   0.   0.   0.  -1.  -1.  -1.
  GOES PREDICTORS       -2.  -3.  -4.  -5.  -6.  -6.  -6.  -6.  -5.  -4.  -4.  -5.
  OCEAN HEAT CONTENT     0.   0.  -1.  -1.  -1.  -1.  -1.  -1.   0.   0.   0.   0.
                        ----------------------------------------------------------
  TOTAL CHANGE          -1.  -2.  -5.  -6.  -8. -11. -13. -16. -20. -27. -30. -33.

                CURRENT MAX WIND (KT):   55. LAT, LON:   19.0   144.6

      ** 2015 E. Pacific RI INDEX EP052016 DARBY      07/21/16  12 UTC **
 (SHIPS-RII PREDICTOR TABLE for 30 KT OR MOREMAXIMUM WIND INCREASE IN NEXT 24-h)
 
     Predictor             Value   RI Predictor Range  Scaled Value(0-1) % Contribution
 12 HR PERSISTENCE (KT):     5.0     -22.0  to   38.5       0.45         999.0
 POT = MPI-VMAX (KT)   :    70.8      40.3  to  144.5       0.29         999.0
 HEAT CONTENT (KJ/cm2) :     1.8       0.0  to   75.9       0.02         999.0
 STD DEV OF IR BR TEMP :    19.5      38.9  to    2.1       0.53         999.0
 850-200 MB SHEAR (KT) :    10.3      18.9  to    1.4       0.49         999.0
 MAXIMUM WIND (kt)     :    55.0      22.5  to  132.0       0.91         999.0
 D200 (10**7s-1)       :   -17.0     -11.0  to  135.3       0.00           0.0
 BL DRY-AIR FLUX (w/m2):   452.4     638.0  to  -68.2       0.26         999.0
 2nd PC OF IR BR TEMP  :    -0.1       2.1  to   -1.7       0.57         999.0
 % AREA WITH TPW <45 mm:    43.8      81.4  to    0.0       0.46         999.0
 
 SHIPS Prob RI for 20kt/ 12hr RI threshold=   7% is   1.2 times sample mean ( 6.3%)
 SHIPS Prob RI for 25kt/ 24hr RI threshold=   0% is   0.0 times sample mean (12.9%)
 SHIPS Prob RI for 30kt/ 24hr RI threshold=   0% is   0.0 times sample mean ( 8.6%)
 SHIPS Prob RI for 35kt/ 24hr RI threshold=   0% is   0.0 times sample mean ( 5.8%)
 SHIPS Prob RI for 40kt/ 24hr RI threshold=   0% is   0.0 times sample mean ( 4.1%)
 SHIPS Prob RI for 45kt/ 36hr RI threshold=   0% is   0.0 times sample mean ( 7.1%)
 SHIPS Prob RI for 55kt/ 48hr RI threshold=   0% is   0.0 times sample mean ( 5.9%)
 
 Matrix of RI probabilities
 ---------------------------------------------------------------------
  RI (kt / h)  | 20/12 | 25/24 | 30/24 | 35/24 | 40/24 | 45/36 | 55/48
 ---------------------------------------------------------------------
   SHIPS-RII:     7.4%    0.0%    0.0%    0.0%    0.0%    0.0%    0.0%
    Logistic:     0.7%    0.7%    0.6%    0.2%    0.1%    0.2%    0.0%
    Bayesian:     0.0%    0.2%    0.1%    0.0%    0.0%    0.0%    0.0%
   Consensus:     2.7%    0.3%    0.2%    0.1%    0.0%    0.1%    0.0%

   ##         ANNULAR HURRICANE INDEX (AHI) EP052016 DARBY      07/21/16  12 UTC         ##
   ## STORM NOT ANNULAR, SCREENING STEP FAILED, NPASS=4 NFAIL=3                          ##
   ## AHI=  0   (AHI OF 100 IS BEST FIT TO ANN. STRUC., 1 IS MARGINAL, 0 IS NOT ANNULAR) ##

[tolakram]

Live IR loop

http://weather.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-W%20PACUS&lat=19&lon=-146&info=ir&zoom=2&width=1000&height=800&type=Animation&quality=85&palette=ir1.pal&numframes=14

[cycloneye]

TROPICAL STORM DARBY DISCUSSION NUMBER 40
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP052016
500 AM HST THU JUL 21 2016

The satellite cloud pattern around Darby remains well-organized, but
the area of cold tops has decreased a bit since last evening.
Microwave passes at 1059 and 1156 UTC also showed good banding
wrapping from west through south through east through north of the
center. Comparison of 36 and 89 GHz imagery shows the center sloping
up to the southeast. The latest subjective Dvorak intensity
estimates were 3.0/45 kt from SAB, JTWC and HFO. The initial
intensity for this advisory has been kept at 55 kt.

The center of Darby is not easy to locate precisely with GOES 15
imagery, but the recent microwave passes show that the storm has
continued to track south of west. The track forecast has again
shifted very slightly southwest from the previous track over the
next 72 hours. The mid-level ridge northwest of Darby will steer the
storm west southwest with a very gradual turn to the west. Beyond 72
hours, Darby is expected to turn rather sharply toward the
northwest as a low aloft in the Gulf of Alaska digs strongly south.
This is a rather unusual track for a tropical cyclone in the central
Pacific, so there is a greater than normal amount of uncertainty to
the forecast. Since Darby continues to track toward the main
Hawaiian Islands it will probably be necessary to issue a Tropical
Storm Watch later today.

Darby will be moving over .5 degree Celsius warmer water the next
couple of days, while vertical wind shear is forecast to increase
slightly. Darby is expected to remain surrounded by fairly dry air.
With no big changes in the environment, little change in intensity
is expected for the next few days. As Darby turns northwest in 72
hours it will be moving over cooler water and vertical wind shear
will increase. Darby is expected to weaken steadily through day 5.
The official forecast lies close to the IVCN consensus.

Interests in the Hawaiian islands should monitor the progress of
Darby. However, it is important not to focus too closely on the
exact track and intensity forecasts because the average track error
72 hours out is near 100 miles, while the average intensity error is
about 15 kt. In addition, the hazards of a tropical cyclone can
extend over a broad area well away from the center.




FORECAST POSITIONS AND MAX WINDS

INIT 21/1500Z 18.9N 145.2W 55 KT 65 MPH
12H 22/0000Z 18.6N 147.0W 55 KT 65 MPH
24H 22/1200Z 18.4N 149.2W 55 KT 65 MPH
36H 23/0000Z 18.5N 151.1W 55 KT 65 MPH
48H 23/1200Z 18.7N 152.5W 55 KT 65 MPH
72H 24/1200Z 20.2N 154.4W 55 KT 65 MPH
96H 25/1200Z 23.0N 156.0W 50 KT 60 MPH
120H 26/1200Z 26.5N 158.5W 40 KT 45 MPH

$$
Forecaster Donaldson

[gatorcane]

[bg1]

That cone is getting a bit too close for comfort.
If Darby makes landfall in Hawaii, it will surpass Florida in tropical storm hits since 2014.

[cycloneye]

Code: Select all

WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1000 AM EDT THU 21 JULY 2016
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
         VALID 22/1100Z TO 23/1100Z JULY 2016
         TCPOD NUMBER.....15-056

I.  ATLANTIC REQUIREMENTS
    1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
    2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.

II. PACIFIC REQUIREMENTS
    1. TROPICAL STORM DARBY
       FLIGHT ONE - TEAL 76           FLIGHT TWO - TEAL 77
       A. 22/1800Z                    A. 23/0600Z
       B. AFXXX 0105E DARBY           B AFXXX 0205E DARBY
       C. 22/1600Z                    C. 23/0300Z
       D. 18.5N 150.0W                D. 18.7N 151.6W
       E. 22/1730Z TO 22/2000Z        E. 23/0430Z TO 23/0700Z
       F. SFC TO 10,000 FT            F. SFC TO 10,000 FT

    2. SUCCEEDING DAY OUTLOOK: BEGIN 6-HRLY FIXES AT 23/1800Z
       NEAR 19.2N 152.7W

[wxman57]

That cone is getting a bit too close for comfort.
If Darby makes landfall in Hawaii, it will surpass Florida in tropical storm hits since 2014.

The cone is quite irrelevant. It says absolutely nothing about the level of uncertainty in Darby's track, nor does it provide an indication of potential impact. The cone simply identifies how far off NHC/CPHC forecasts have been off over the past 5 years. For the past 5 years, track forecasts were within that cone (center of the storm) 66.7% of the time. That's all the cone means. It never changes from storm to storm, nor does it change when there is significant model divergence, as there is with Darby.

I think there's a good chance that the Big Island will be struck directly by Darby, putting tropical storm conditions into Hilo Saturday night. The Euro is indicating 7-12 inches of rain across the Big Island from Saturday afternoon through Sunday afternoon. The CPHC will likely be adjusting their track westward in future advisories.

[Alyono]

MU now has landfall

[CrazyC83]

Could it be a worst case scenario and duck under the Big Island before turning hard to Oahu?

[wxman57]

Could it be a worst case scenario and duck under the Big Island before turning hard to Oahu?

That's possible, but shear would increase significantly as it neared Oahu, resulting in rapid weakening.

[gatorcane]

12Z MU with direct hit on Hawaii, fortunately not that strong though:

[JtSmarts]

Hopefully everyone in the Big island are getting prepared, Iselle showed it doesn't take a very strong storm to cause big problems.

[Alyono]

it has 40 to 50 kt winds at landfall