EPAC: HILDA- Post-Tropical

[cycloneye]

HURRICANE HILDA DISCUSSION NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL EP102015
800 PM PDT FRI AUG 07 2015

The hurricane continues to intensify at a rapid pace. An earlier
AMSR-2 microwave overpass revealed that Hilda's inner core was
extremely compact. In addition, visible and infrared geostationary
satellite imagery indicates that the system's eye has become better
defined, and the areal extent of cold cloud-top temperatures
surrounding the eye has increased over the past several hours. The
current intensity estimate is raised to 90 kt, in accordance with a
Dvorak estimate from TAFB. There is strong upper-level outflow
associated with the cyclone, particularly over the western
semicircle of the circulation.

Hilda's intensification is forecast to continue over the next 12 to
24 hours, while vertical wind shear is expected to remain weak. In
about 48 hours, the hurricane is forecast to begin encountering
stronger shear associated with an upper-tropospheric trough near the
Hawaiian Islands. Global models predict that the shear will increase
greatly beyond 72 hours. Therefore a weakening trend is forecast to
commence in 48 hours, with rapid weakening likely in the latter part
of the forecast period. The official intensity forecast is in good
agreement with the latest SHIPS and LGEM guidance.

The initial motion estimate is slightly north of due west, or
280/13 kt. The track forecast reasoning has not changed much since
the last advisory. Hilda's track should gradually bend toward the
west-northwest and northwest over the next 96 hours or so, as the
cyclone moves to the south of a mid-level ridge and approaches a
cyclonic circulation just to the north of the Hawaiian Islands.
Near the end of the forecast period, the rapidly weakening system
should become a more shallow circulation, and turn more toward the
west within the low- to mid-tropospheric flow. The official track
forecast is in good agreement with the latest dynamical model
consensus.

Since Hilda will be moving into the central Pacific basin very
soon, future information on this system will be issued by the
Central Pacific Hurricane Center in Honolulu, Hawaii.


FORECAST POSITIONS AND MAX WINDS

INIT 08/0300Z 13.0N 139.6W 90 KT 105 MPH
12H 08/1200Z 13.4N 141.4W 100 KT 115 MPH
24H 09/0000Z 14.1N 143.5W 110 KT 125 MPH
36H 09/1200Z 14.9N 145.4W 110 KT 125 MPH
48H 10/0000Z 15.8N 147.2W 95 KT 110 MPH
72H 11/0000Z 17.8N 149.5W 75 KT 85 MPH
96H 12/0000Z 19.5N 151.0W 50 KT 60 MPH
120H 13/0000Z 20.6N 153.0W 35 KT 40 MPH

$$
Forecaster Pasch

[Kingarabian]

90kts.. Conservative, conservative.

[galaxy401]

And it probably won't go much higher knowing how much the CPHC relies on Dvorak.

[Yellow Evan]

If this was Stewart, Blake, Kimberlian, or Beven, this would be 95 or 100 knots.

[Kingarabian]

Man they didn't even go with 95kts, a blend of SAB and TAFB. Seriously wish ADT was cooperating.

[Yellow Evan]

And it probably won't go much higher knowing how much the CPHC relies on Dvorak.

Don't think JTWC/CPHC are stuck to constraints. But you never know with the CPHC. I hope Birichard is on as IMO he's their best forecaster.

[Kingarabian]

[Yellow Evan]

NHC probably went 90 due to lag. But it's often popular belief on here that lag isn't an issue in smaller storms. Currently looking in to this.

Appearance wise, this is a Category 3 hurricane, no question about it.

[Yellow Evan]

ADT continues to miss it:

2015AUG08 010000 4.4 981.5 74.6 4.4 4.4 4.1 MW ON OFF OFF -61.56 -73.35 UNIFRM N/A 42.2 12.88 139.27 SPRL GOES15 15.9
2015AUG08 013000 4.4 981.4 74.6 4.4 4.4 4.0 MW ON OFF OFF -62.36 -72.75 UNIFRM N/A 42.2 12.95 139.30 FCST GOES15 16.0
2015AUG08 020000 4.4 981.4 74.6 4.4 4.4 3.9 MW ON OFF OFF -51.66 -72.52 UNIFRM N/A 42.2 12.96 139.40 FCST GOES15 16.0
2015AUG08 023000 4.5 979.7 77.0 4.5 4.5 4.0 MW ON OFF OFF -50.46 -72.93 UNIFRM N/A 42.2 12.98 139.50 FCST GOES15 16.1

[Kingarabian]

NHC probably went 90 due to lag. But it's often popular belief on here that lag isn't an issue in smaller storms. Currently looking in to this.

Appearance wise, this is a Category 3 hurricane, no question about it.

I'm not sure about the physics, but don't winds have to be at a certain speed first for the eye to become visible.

Does the eye clear out first allowing the winds to increase?

Does eye contraction and wind increase happen simultaneously?

[Yellow Evan]

NHC probably went 90 due to lag. But it's often popular belief on here that lag isn't an issue in smaller storms. Currently looking in to this.

Appearance wise, this is a Category 3 hurricane, no question about it.

I'm not sure about the physics, but don't winds have to be at a certain speed first for the eye to become visible.

Does the eye clear out first allowing the winds to increase?

Does eye contraction and wind increase happen simultaneously?

Not necessarily AFAIK. This is a hotly debated topic, but general consensus is wind lags satellite. This is up for debate more so in pinhole eye storms (thanks to Wilma) and smaller systems, and as such, Dvorak agencies sometimes break constraints in these situations. This is more of an issue, not so much in the EPAC or ATL, but in the Indian Ocean, where small systems are common. Of curse, we have no Recon there (and the historical record of Recon for small systems seems quite small in the ATL/EPAC/WPAC), so we don't know for sure

[Yellow Evan]

Last vis of the night. This will be a monster soon.

[Yellow Evan]

Eye a little cooler in recent frame.

[Kingarabian]

[Yellow Evan]

Shear appears to have increased (noticed how it's titled to the east). Likely steady state for now. Any relaxation of the shear will give it a chance to clear an eye and we're looking at a Cat 3-4

[Yellow Evan]

EP, 10, 201508080530, 10, DVTS, CI, , 1310N, 14010W, , 1, 102, 2, , , , , , , , , , , , , , , , , C, SAB, GS, IM, 1, 5555 /////, , , GOES15, CSC, T, DT=5.5 BO EYE MET=4.5 PT=5.0 FTBO R

[Yellow Evan]

TPPZ02 PGTW 080617

A. HURRICANE 10E (HILDA)

B. 08/0531Z

C. 13.08N

D. 140.16W

E. FIVE/GOES15

F. T5.0/5.0

G. IR/EIR

H. REMARKS: 46A/PBO EMBD CNTR/ANMTN. LLCC EMBEDDED IN W YIELDS
A CF OF 5.0. MET AND PT ARE UNAVAILABLE. DBO DT.

I. ADDITIONAL POSITIONS: NONE


LEMBKE

[Yellow Evan]

TXPN41 PHFO 080546
TCSNP1

CENTRAL PACIFIC TROPICAL CYCLONE SUMMARY - FIXES
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI
0550 UTC SAT AUG 08 2015

A. Hurricane Hilda.

B. 08/0530Z.

C. 13.1°N.

D. 140.2°W.

E. Goes-15.

F. T5.0/5.0/d1.5/24 hours.

G. Vis/eir/ir.

H. Remarks: Eye pattern with EIR bd black shade eye > 30 nm within white ring gives a 6.0 with an adjustment of -1.0 for a total DT of 5.0. MET is 4.0. PT is 4.5. FT based on DT.

I. Addl positions none.

$$

Ryshko.

CPHC will probs go 90 here. Maybe 95.

[Yellow Evan]

Why toy with the pressure CPHC?


EP, 10, 2015080806, , BEST, 0, 132N, 1402W, 90, 973, HU, 34, NEQ, 60, 70, 50, 60, 1008, 150, 10, 0, 0, E, 0, , 0, 0, HILDA, D, 0, , 0, 0, 0, 0, genesis-num, 014,
EP, 10, 2015080806, , BEST, 0, 132N, 1402W, 90, 973, HU, 50, NEQ, 30, 40, 20, 30, 1008, 150, 10, 0, 0, E, 0, , 0, 0, HILDA, D, 0, , 0, 0, 0, 0, genesis-num, 014,
EP, 10, 2015080806, , BEST, 0, 132N, 1402W, 90, 973, HU, 64, NEQ, 15, 15, 10, 10, 1008, 150, 10, 0, 0, E, 0, , 0, 0, HILDA, D, 0, , 0, 0, 0, 0, genesis-num, 014,

[Yellow Evan]

NRL Navy site not working or does Hilda look like a 3 year old's artwork?