EPAC: JIMENA - Post-Tropical

[cycloneye]

HURRICANE JIMENA DISCUSSION NUMBER 16
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132015
800 AM PDT SUN AUG 30 2015

Infrared satellite images and a recent GCOM microwave pass indicate
that there is still some evidence of a double eyewall structure.
The southern portion of Jimena's inner eyewall has eroded a little
during the past few hours, causing a slightly asymmetric
presentation. The initial wind speed is maintained at 115 kt, based
on a blend of the satellite intensity estimates from TAFB, SAB, and
ADT values from CIMSS at the University of Wisconsin, though it is
possible that Jimena could be a little less intense.

The atmospheric environment is expected to remain conducive for
Jimena to remain a strong cyclone for the next several days as
the SHIPS model shows the wind shear remaining less than 10 kt. The
only negative environmental factor is cooler water with lower
oceanic heat content along the expected track. Most of the guidance
shows a slow decay of the hurricane during the next several days,
and the NHC intensity forecast follows that theme. This forecast
is in best agreement with the SHIPS model.

Jimena is moving west-northwestward at about 12 kt steered by a
subtropical ridge to its north and northeast. This general motion
is expected to persist for another day or two. After that time,
the hurricane is expected to decelerate in response to weakening
steering currents caused by an amplifying trough extending
southwestward from the western United States. The new track
forecast is adjusted a little to the right of the previous one to
come in better agreement with the latest runs of the GFS and ECMWF
models.

FORECAST POSITIONS AND MAX WINDS

INIT 30/1500Z 14.2N 129.6W 115 KT 130 MPH
12H 31/0000Z 14.9N 131.6W 110 KT 125 MPH
24H 31/1200Z 15.6N 134.2W 110 KT 125 MPH
36H 01/0000Z 16.2N 136.4W 105 KT 120 MPH
48H 01/1200Z 16.8N 138.2W 100 KT 115 MPH
72H 02/1200Z 17.7N 140.6W 95 KT 110 MPH
96H 03/1200Z 18.5N 142.3W 85 KT 100 MPH
120H 04/1200Z 19.2N 143.4W 75 KT 85 MPH

$$
Forecaster Cangialosi

[Yellow Evan]

Inner eyewall might finally be gone. Eye still needs to re-clear.

[Yellow Evan]

----- Current Analysis -----
Date : 30 AUG 2015 Time : 183000 UTC
Lat : 14:34:09 N Lon : 130:27:18 W


CI# /Pressure/ Vmax
6.2 / 945.0mb/119.8kt


Final T# Adj T# Raw T#
6.2 6.7 6.7

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

Center Temp : +6.4C Cloud Region Temp : -72.1C

Scene Type : EYE

[Yellow Evan]

Eye warming




----- Current Analysis -----
Date : 30 AUG 2015 Time : 190000 UTC
Lat : 14:35:24 N Lon : 130:33:35 W


CI# /Pressure/ Vmax
6.4 / 940.6mb/124.6kt


Final T# Adj T# Raw T#
6.4 6.8 6.8

Estimated radius of max. wind based on IR : 22 km

Center Temp : +11.7C Cloud Region Temp : -72.0C

Scene Type : EYE

[1900hurricane]

Yep, eye continues to warm coming off the completed eyewall replacement cycle and is now north of 15*C as measured by GOES-15. If it can climb to around 18*C for a few consecutive frames while maintaining its current convective structure (no appreciable cloud top warming), I feel like that should be enough for a category 5 classification, although the current warm medium grey eye embedded in white could yield a T# of 7.0 if a subjective Dvorak analysis were done right now.

[cycloneye]

HURRICANE JIMENA DISCUSSION NUMBER 17
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132015
200 PM PDT SUN AUG 30 2015

After Jimena's cloud pattern appeared somewhat ragged this
morning, it has recently become more symmetric and better organized.
The latest infrared images indicate that a ring of cloud tops colder
than -70 deg C surround the center, and the eye has increased in
diameter and become more distinct. The larger eye suggests that
eyewall replacement could now be complete, and this is likely the
reason why the hurricane has begun to re-intensify. Dvorak
classifications at 1800 UTC were 6.0/115 kt from SAB and 6.5/127 kt
from TAFB, with the latest UW-CIMSS ADT value between these two
estimates. Based on the latest appearance of Jimena, the initial
wind speed is set near the high end of the estimates at 125 kt.

As mentioned in previous discussions, Jimena is expected to remain
in a low wind shear environment for the next several days. However,
the cyclone is expected to track over progressively cooler water,
which should cause the hurricane to slowly weaken. The official
intensity forecast shows some short-term strengthening, following
the current trend, and then predicts a slow decay. This forecast is
higher than all of the guidance during the next day or so, but falls
in line with the SHIPS model from 36-120 h.

Jimena is moving a little faster toward the west-northwest, 295/13
kt. This motion is expected to continue for about 24 hours while a
subtropical ridge remains to the north and northeast of the
cyclone. After that time, Jimena is forecast to decelerate as
steering currents weaken in response to an amplifying trough
extending southwestward from the western United States. There was
little change in the latest model guidance, and the NHC forecast is
largely an update of the previous one. This forecast lies close to
the GFS and ECMWF models.

FORECAST POSITIONS AND MAX WINDS

INIT 30/2100Z 14.7N 130.9W 125 KT 145 MPH
12H 31/0600Z 15.2N 133.0W 135 KT 155 MPH
24H 31/1800Z 16.0N 135.5W 125 KT 145 MPH
36H 01/0600Z 16.6N 137.4W 115 KT 130 MPH
48H 01/1800Z 17.1N 138.9W 105 KT 120 MPH
72H 02/1800Z 18.0N 141.1W 95 KT 110 MPH
96H 03/1800Z 18.8N 142.5W 85 KT 100 MPH
120H 04/1800Z 19.8N 143.5W 75 KT 85 MPH

$$
Forecaster Cangialosi

[Yellow Evan]

I'd say 125-130 knots now.

[CrazyC83]

I'd want to see the eye at least partially surrounded by medium grey to get to a Cat 5. Looks definitely like a T6.5 to me.

[Yellow Evan]

I'd want to see the eye at least partially surrounded by medium grey to get to a Cat 5. Looks definitely like a T6.5 to me.

That's not a requirement according to Dvorak for a 7.0 rating, and there have been plenty of Category 5's without CMG.

[EquusStorm]

Wow. Jimena definitely has impressed me in the last 12 hours or so. After her inner core struggles yesterday, I didn't expect to see such a rapid rebound. Very impressive satellite presentation at the moment.

[Yellow Evan]

I still would like to see a thicker NE for a 7.0. Close though.

[Yellow Evan]

----- Current Analysis -----
Date : 30 AUG 2015 Time : 203000 UTC
Lat : 14:37:09 N Lon : 130:56:55 W


CI# /Pressure/ Vmax
6.7 / 933.5mb/132.2kt


Final T# Adj T# Raw T#
6.7 6.8 6.8

Estimated radius of max. wind based on IR : 21 km

Center Temp : +14.7C Cloud Region Temp : -71.8C

Scene Type : EYE

[1900hurricane]

Yeah, white ring is no longer wide enough around the entirety of the eye for a 7.0. We'll see how things go though, eyewall replacement was just completed and conditions look pretty favorable for at least sustained intensity. Maybe we'll see some cloud top cooling once the sun goes down.

[Yellow Evan]

Cloud tops have cooled in most recent frames, so we'll see. One frame could be the difference between T6.5 and T7.0.

[Kingarabian]

Really close to a Cat.5.

[Yellow Evan]

Don't know why ADT fell.

----- Current Analysis -----
Date : 30 AUG 2015 Time : 213000 UTC
Lat : 14:40:47 N Lon : 131:09:48 W


CI# /Pressure/ Vmax
6.7 / 933.5mb/132.2kt


Final T# Adj T# Raw T#
6.7 6.6 6.6

Estimated radius of max. wind based on IR : 22 km

Center Temp : +13.5C Cloud Region Temp : -70.9C

Scene Type : EYE

[1900hurricane]

The calculated average CDO temp fell by about 1*C over the past couple frames. ADT is very picky about its CDO temps.

[Yellow Evan]

----- Current Analysis -----
Date : 30 AUG 2015 Time : 220000 UTC
Lat : 14:42:33 N Lon : 131:16:26 W


CI# /Pressure/ Vmax
6.7 / 933.5mb/132.2kt


Final T# Adj T# Raw T#
6.7 6.7 6.7

Estimated radius of max. wind based on IR : 22 km

Center Temp : +14.8C Cloud Region Temp : -71.1C

Scene Type : EYE

[1900hurricane]

My premature intensity analysis for 00Z would likely be 130 kt.

[Yellow Evan]