EPAC: HILDA- Post-Tropical

[Kingarabian]

18z GFS recurves it before the Big Island.

[Yellow Evan]

18z GFS recurves it before the Big Island.

...before it rebulds the ridge and sends it W.

Question here is will the ridge re-build in time.

[Yellow Evan]

TXPZ26 KNES 070024
TCSENP
CCA

A. 10E (hILDA)

B. 07/0000Z

C. 12.7N

D. 134.1W

E. THREE/GOES-W

F. T3.0/3.0/D1.5/24HRS

G. IR/EIR/VIS

H. REMARKS...COR TO ADD NAME IN LINE A... SYSTEM HAS DEVELOPED RAPIDLY
INTO A SMALL TIGHT LITTLE STORM WITH CENTER IN A 1.24 DEGREE CDO OR
BANDING OF 7/10 FOR A DT=3.0. MET=3.0 ON FAST CURVE AND PAT ALSO 3.0. FT
IS BASED ON DT.

I. ADDL POSITIONS

NIL


...SWANSON

More than 7/10 banding here IMO.

[Yellow Evan]

EP, 10, 2015080700, , BEST, 0, 127N, 1340W, 50, 999, TS, 34, NEQ, 50, 50, 30, 50, 1008, 160, 10, 0, 0, E, 0, , 0, 0, HILDA, D, 0, , 0, 0, 0, 0, genesis-num, 014,
EP, 10, 2015080700, , BEST, 0, 127N, 1340W, 50, 999, TS, 50, NEQ, 20, 20, 0, 20, 1008, 160, 10, 0, 0, E, 0, , 0, 0, HILDA, D, 0, , 0, 0, 0, 0, genesis-num, 014,

[Kingarabian]

I'd go with 55kts but 50kts is okay since there isn't a warm spot or any new microwave imagery to show an eye forming.

[Yellow Evan]

Meh, the two microwave passes since 20z look meh, but then again it's only a tropical storm.

[Kingarabian]

000
WTPZ45 KNHC 070242
TCDEP5

TROPICAL STORM HILDA DISCUSSION NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL EP102015
800 PM PDT THU AUG 06 2015

The cloud pattern of Hilda has not changed much since the previous
advisory. The cyclone has a couple of curved convective bands with
a small symmetric central dense overcast. Recent microwave data
also indicates that the inner core has not become any better
organized during the afternoon. A blend of the subjective and
objective Dvorak T-numbers support maintaining an initial intensity
of 50 kt.

Hilda is expected to remain in an environment of low vertical wind
shear and over warm sea surface temperatures during the next couple
of days. These conditions favor intensification and the NHC
forecast brings Hilda to hurricane strength within the next 24
hours. The new official forecast shows a slightly higher peak
intensity in about 48 hours, which is a blend of the latest
statistical guidance. After that time, a drier and more stable air
mass and increasing southwesterly shear around 96 h are expected to
induce weakening. The NHC forecast is below the model guidance
late in the forecast period, since the small tropical cyclone is
likely to spin down more quickly as a result of the strong shear.

The tropical storm is moving due west or 270 degrees at 12 kt.
The forecast reasoning remains the same as before. Hilda is
expected to turn west-northwestward in about 36 hours when it nears
the western periphery of a subtropical ridge to its north. In
about 96 hours, Hilda is forecast to turn northwestward due to a
developing weakness in the subtropical ridge. The model guidance
is in good agreement through day 3, but diverge somewhat thereafter.
The ECMWF and UKMET show a faster forward motion and are along the
western edge of the guidance envelope. Meanwhile, the GFS and HWRF
are along the eastern edge. The updated NHC forecast is similar to
the previous advisory and near the GFS ensemble mean late in the
period.


FORECAST POSITIONS AND MAX WINDS

INIT 07/0300Z 12.7N 134.6W 50 KT 60 MPH
12H 07/1200Z 12.7N 136.3W 60 KT 70 MPH
24H 08/0000Z 13.0N 138.5W 70 KT 80 MPH
36H 08/1200Z 13.7N 140.5W 80 KT 90 MPH
48H 09/0000Z 14.5N 142.5W 80 KT 90 MPH
72H 10/0000Z 16.3N 146.1W 70 KT 80 MPH
96H 11/0000Z 17.8N 148.5W 60 KT 70 MPH
120H 12/0000Z 19.0N 150.0W 40 KT 45 MPH

$$
Forecaster Brown

[Yellow Evan]

What I don't understand is why they lowered the pressure to 999 mbar and kept the winds at 50 knots?

[Yellow Evan]

Might be on the verge of inheriting a crap ton of dry air.

[Yellow Evan]

And shear has killed it. Why did I know this would happen as soon as I thought this would RI?

[Kingarabian]

What I don't understand is why they lowered the pressure to 999 mbar and kept the winds at 50 knots?

Smaller storms tend to have lower pressures.

GFS and Euro closer to the big island of Hawaii. GFS really builds back that ridge and forces it west.

[Kingarabian]

000
WTPZ45 KNHC 070837
TCDEP5

TROPICAL STORM HILDA DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL EP102015
200 AM PDT FRI AUG 07 2015

A GPM Microwave Imager pass from 0431 UTC revealed that Hilda's
center was located just under the eastern edge of the deep
convection due to some easterly shear. The overall cloud pattern
has not really improved since earlier advisories, and the initial
intensity remains 50 kt. This is supported by Dvorak estimates of
T3.5/55 kt from TAFB and T3.0/45 kt from SAB. Although Hilda's
intensity has been steady for the past 12 hours, easterly shear
is relaxing, and the cyclone should be able to strengthen soon.
Hilda is forecast to be in a low-shear environment and over sea
surface temperatures of 27-29C during the next three days or so,
during which time intensification is expected. On days 4 and 5,
weakening is anticipated as southwesterly shear of 25-35 kt begins
to affect the cyclone. The NHC intensity forecast is near the
upper bound of the guidance and shows a peak intensity occurring in
about 48 hours.

Hilda is moving due west, or 270/11 kt. The cyclone should turn
west-northwestward by 36 hours as it approaches a weakness in the
subtropical ridge. Then, a mid- to upper-level low is expected to
develop north of the Hawaiian Islands in about three days, which
should cause Hilda to turn northwestward and north-northwestward on
days 4 and 5. The track guidance generally agrees on this scenario,
but there is significant discrepancy on how sharply Hilda will turn
after 72 hours. The GFS and GFDL, which depict a stronger cyclone,
have sharper turns and end up on the east side of the guidance
envelope. The ECMWF, on the other hand, does not intensify Hilda as
much and is well to the west of the other track models. The updated
NHC track forecast shows a sharper turn than in the previous
advisory, but the turn is not nearly as sharp as suggested by the
GFS, GFDL, and the various consensus models.

FORECAST POSITIONS AND MAX WINDS

INIT 07/0900Z 12.6N 135.6W 50 KT 60 MPH
12H 07/1800Z 12.8N 137.3W 60 KT 70 MPH
24H 08/0600Z 13.2N 139.3W 65 KT 75 MPH
36H 08/1800Z 13.9N 141.3W 70 KT 80 MPH
48H 09/0600Z 14.7N 143.3W 75 KT 85 MPH
72H 10/0600Z 16.1N 147.1W 70 KT 80 MPH
96H 11/0600Z 18.0N 149.0W 60 KT 70 MPH
120H 12/0600Z 20.5N 150.0W 45 KT 50 MPH

$$
Forecaster Berg

[Kingarabian]

Looks like a hurricane to me.

[Kingarabian]

TXPZ26 KNES 071824
TCSENP

A. 10E (HILDA)

B. 07/1800Z

C. 12.6N

D. 137.7W

E. ONE/GOES-W

F. T4.0/4.0/D1.0/18HRS

G. IR/EIR/VIS

H. REMARKS...CLOUD FILLED B EYE SURROUNDED BY W RING AND EMBEDDED
IN LG YIELDS AN E# OF 5.0. DT IS 4.0 AFTER SUBTRACTING 1.0 FOR EYE
ADJUSTMENT. MET IS 3.5 AND PT IS 4.0. FT IS BASED ON DT.

I. ADDL POSITIONS

NIL


...VELASCO

EP, 10, 201508071800, 10, DVTS, CI, , 1260N, 13770W, , 1, 65, 2, , , , , , , , , , , , , , , , , E, SAB, JV, VIM, 1, 4040 /////, , , GOES15, LLCC, T, DT=4.0 BO EYE MET=3.5 PT=4.0 FTBO DT
EP, 10, 201508071800, 10, DVTS, CI, , 1270N, 13760W, , 3, 55, 2, 994, 2, DVRK, , , , , , , , , , , , , , E, TAFB, DS, VI, 5, 3535 /////, , , GOES15, CSC, T,

[Yellow Evan]

What I don't understand is why they lowered the pressure to 999 mbar and kept the winds at 50 knots?

Smaller storms tend to have lower pressures.

GFS and Euro closer to the big island of Hawaii. GFS really builds back that ridge and forces it west.

Smaller storms=higher pressures due to less space for the isobars.

[Yellow Evan]

Old disco from 8 AM:

000
WTPZ45 KNHC 071435
TCDEP5

TROPICAL STORM HILDA DISCUSSION NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL EP102015
800 AM PDT FRI AUG 07 2015

Infrared satellite data, along with VIIRS moonlight visible imagery
and a just received AMSR-2 overpass, show that Hilda is maintaining
strong convection near the center. However, the system continues to
have a sheared appearence, which is somewhat surprising since the
available data show less than 10 kt of shear. The various satellite
intensity estimates range between 45-55 kt, so the initial intensity
remains 50 kt. The cirrus outflow is good to the west and poor to
the east.

The initial motion is 275/11. For the next 48-72 hours, Hilda
should be steered westward to west-northwestward by the deep-layer
subtropical ridge to its north. After that time, a mid- to
upper-level low is expected to develop north of the Hawaiian
Islands, which should cause Hilda to turn northwestward and
north-northwestward. The track guidance again generally agrees
on this scenario, but there remains a significant spread in how
sharply Hilda will turn based on the strength of the cyclone after
72 hours. The GFS, GFDL, and GFDN, which depict a stronger cyclone,
have sharper turns and end up on the east side of the guidance
envelope. The ECMWF, HWRF, and GFS ensemble mean forecast a weaker
Hilda, and they show a more westward motion. The UKMET and the
various consensus models are between these extremes. The new
forecast track, which is little changed from the previous track,
follows this part of the guidance.

The dynamical models are in good agreement that whatever shear is
occurring should diminish in 24 hours or less. This should allow a
faster rate of development, with Hilda forecast to become a
hurricane in 24-36 hours and reach its peak intensity in 48-72
hours. After 72 hours, the cyclone is expected to encounter strong
southwesterly vertical shear and decreasing sea surface
temperatures, and this combination should cause significant
weakening. The new intensity forecast has minor adjustments from
the previous forecast and is in best overall agreement with the
intensity consensus.

FORECAST POSITIONS AND MAX WINDS

INIT 07/1500Z 12.8N 136.7W 50 KT 60 MPH
12H 08/0000Z 13.0N 138.3W 55 KT 65 MPH
24H 08/1200Z 13.6N 140.5W 60 KT 70 MPH
36H 09/0000Z 14.3N 142.5W 70 KT 80 MPH
48H 09/1200Z 15.1N 144.5W 75 KT 85 MPH
72H 10/1200Z 16.5N 147.5W 75 KT 85 MPH
96H 11/1200Z 18.5N 149.5W 55 KT 65 MPH
120H 12/1200Z 20.5N 150.5W 40 KT 45 MPH

$$
Forecaster Beven

[Kingarabian]

She's looking good.

[Yellow Evan]

Code: Select all

                    * EAST PACIFIC SHIPS INTENSITY FORECAST          *
                    * IR SAT DATA AVAILABLE,       OHC AVAILABLE     *
                    *  HILDA       EP102015  08/07/15  18 UTC        *

TIME (HR)          0     6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    60    64    68    72    74    78    77    75    71    63    53    45    36
V (KT) LAND       60    64    68    72    74    78    77    75    71    63    53    45    36
V (KT) LGE mod    60    65    69    73    77    81    82    79    74    65    55    46    38
Storm Type      TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP

SHEAR (KT)        10     8     8     5     4     1     4    11    18    25    37    45    46
SHEAR ADJ (KT)     0     0     0     4     5     0    -4    -4    -3     4     1    -2    -3
SHEAR DIR         63    71    82    89    77   158   242   239   238   236   254   262   266
SST (C)         28.6  28.5  28.5  28.4  28.2  27.9  27.6  27.4  27.3  27.1  27.0  27.0  27.0
POT. INT. (KT)   151   150   150   149   147   143   140   137   135   134   132   131   131
200 MB T (C)   -51.7 -51.2 -51.2 -51.4 -51.4 -51.2 -51.8 -51.8 -52.4 -52.4 -53.1 -53.2 -53.6
TH_E DEV (C)       8     8     8     7     7     7     7     7     7     7     6     7     6
700-500 MB RH     60    60    61    61    61    58    54    55    58    59    56    54    51
MODEL VTX (KT)    14    14    15    16    15    16    15    16    18    17    15    14    12
850 MB ENV VOR    17    17    21    19    19    29    29    28    24    26    23    32    13
200 MB DIV         9    27    27    25    13    23    19    40    68    76    37   -15   -15
700-850 TADV      -1    -2    -3    -2    -1     0     3     4     7     8     9     3     0
LAND (KM)       1990  1865  1741  1621  1502  1275  1052   874   734   592   464   411   405
LAT (DEG N)     12.6  12.9  13.1  13.5  13.8  14.5  15.3  16.0  16.7  17.7  19.0  20.0  20.6
LONG(DEG W)    137.6 138.8 139.9 141.0 142.0 144.0 145.9 147.4 148.5 149.5 150.4 150.9 151.1
STM SPEED (KT)    12    11    11    11    10    10     9     7     6     8     6     4     3
HEAT CONTENT      27    18    10     9    12    19    21    29    34    24    21    14    11

  FORECAST TRACK FROM OFCI      INITIAL HEADING/SPEED (DEG/KT):270/ 13      CX,CY: -12/  0
  T-12 MAX WIND:  50            PRESSURE OF STEERING LEVEL (MB):  521  (MEAN=581)
  GOES IR BRIGHTNESS TEMP. STD DEV.  50-200 KM RAD:  12.1 (MEAN=14.5)
  % GOES IR PIXELS WITH T < -20 C    50-200 KM RAD:  78.0 (MEAN=65.0)

                        INDIVIDUAL CONTRIBUTIONS TO INTENSITY CHANGE
                         6   12   18   24   36   48   60   72   84   96  108  120
                        ----------------------------------------------------------
  SAMPLE MEAN CHANGE     0.   0.   0.   1.   1.   1.   0.   0.  -1.  -1.  -2.  -2.
  SST POTENTIAL          1.   2.   3.   4.   5.   6.   5.   5.   4.   3.   1.   1.
  VERTICAL SHEAR MAG     0.   0.   1.   2.   4.   6.   7.   7.   5.   1.  -5. -10.
  VERTICAL SHEAR ADJ     0.   0.   0.   0.  -1.   0.   0.   1.   0.   0.   0.   1.
  VERTICAL SHEAR DIR     1.   2.   3.   4.   6.   4.   2.   0.  -1.  -2.  -3.  -3.
  PERSISTENCE            2.   3.   4.   4.   3.   3.   2.   2.   1.   1.   1.   0.
  200/250 MB TEMP.       0.  -1.  -2.  -3.  -5.  -7.  -9. -11. -11. -11. -10.  -9.
  THETA_E EXCESS         0.   0.   0.   0.  -1.  -1.  -2.  -2.  -2.  -3.  -3.  -4.
  700-500 MB RH          0.   0.   0.   0.   0.   0.   1.   1.   1.   1.   1.   1.
  MODEL VTX TENDENCY     0.   1.   2.   1.   3.   2.   3.   6.   4.   1.   0.  -3.
  850 MB ENV VORTICITY   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.
  200 MB DIVERGENCE      0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.
  850-700 T ADVEC        0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   1.   2.
  ZONAL STORM MOTION     0.   1.   1.   2.   2.   3.   4.   4.   3.   3.   3.   3.
  STEERING LEVEL PRES    0.   0.   0.   0.   0.   0.  -1.  -1.  -1.  -1.  -1.  -1.
  DAYS FROM CLIM. PEAK   0.   0.   0.   0.   0.   0.   0.   0.   1.   1.   1.   1.
  GOES PREDICTORS        0.   1.   1.   1.   1.   1.   0.   0.   0.   0.   0.   0.
  OCEAN HEAT CONTENT     0.   0.   0.   0.   0.   0.   0.   0.   0.   1.   0.   0.
                        ----------------------------------------------------------
  TOTAL CHANGE           4.   8.  12.  14.  18.  17.  15.  11.   3.  -7. -15. -24.

   ** 2013 E. Pacific RI INDEX EP102015 HILDA      08/07/15  18 UTC **
           ( 30 KT OR MORE MAX WIND INCREASE IN NEXT 24 HR)
 
 12 HR PERSISTENCE (KT):  10.0 Range:-22.0 to  38.5 Scaled/Wgted Val:  0.5/  1.2
 850-200 MB SHEAR (KT) :   7.1 Range: 18.7 to   1.4 Scaled/Wgted Val:  0.7/  1.0
 POT = MPI-VMAX (KT)   :  89.4 Range: 40.3 to 141.7 Scaled/Wgted Val:  0.5/  0.5
 STD DEV OF IR BR TEMP :  12.1 Range: 38.9 to   2.4 Scaled/Wgted Val:  0.7/  0.8
 Heat content (KJ/cm2) :  15.2 Range:  3.6 to  75.9 Scaled/Wgted Val:  0.2/  0.1
 D200 (10**7s-1)       :  20.2 Range:-11.0 to 135.3 Scaled/Wgted Val:  0.2/  0.2
 % area w/pixels <-30 C:  70.0 Range: 41.4 to 100.0 Scaled/Wgted Val:  0.5/  0.2
 850-700 MB REL HUM (%):  74.0 Range: 57.6 to  96.8 Scaled/Wgted Val:  0.4/ -0.1
 
 Prob of RI for 25 kt RI threshold=    30% is   2.3 times the sample mean(13.1%)
 Prob of RI for 30 kt RI threshold=    25% is   2.8 times the sample mean( 8.7%)
 Prob of RI for 35 kt RI threshold=    17% is   2.9 times the sample mean( 6.0%)
 Prob of RI for 40 kt RI threshold=    13% is   3.0 times the sample mean( 4.3%)

[Yellow Evan]

Nearing 65 if not there already.

CIMSS/NESDIS-USAF/NRL AMSU TC Intensity Estimation:
TROPICAL STORM HILDA
Friday 07aug15 Time: 1426 UTC
Latitude: 12.52 Longitude: -136.64
Storm position corresponds to AMSU-A FOV 15 [1<--->30]
-----------------------------------------------------------------
| Estimated MSLP: 979 hPa
| Estimated Maximum Sustained Wind: 75 kts
| Estimate Confidence: Fair ( +/- 10mb +/- 12kts )
-----------------------------------------------------------------
Storm is sub-sampled: Bias correction applied is -8.7 hPa
Channel 8 (~150 hPa) Tb Anomaly: 1.48
Channel 7 (~250 hPa) Tb Anomaly: 1.26
Channel 6 (~350 hPa) Tb Anomaly: 00.84
RMW: 19 km
RMW Source is: TPC
Environmental Pressure: 1008 (TPC)
Satellite: NOAA-18

[Kingarabian]

It should be at least 65kts if not 70.

The NHC sided with that AMSU pass yesterday. I can see them doing that today.