EPAC: JIMENA - Post-Tropical

[Yellow Evan]

Not a very good start to an ERC.

[Ntxw]

Still very picturesque

[EquusStorm]

Inner core structure looks a bit improved in the last several hours. Wonder if she'll have time to jump to Cat 5 before beginning the inevitable slow weakening process?

[Kingarabian]

The intensity forecast is subject to a big change now considering that the CPAC is in play now in terms of track. The CPAC has warmer than average waters and decreased shear + increased instability. It will head over cooler waters later than projected.

[Yellow Evan]

Inner core structure looks a bit improved in the last several hours. Wonder if she'll have time to jump to Cat 5 before beginning the inevitable slow weakening process?

Regarding the weakening, I don't know when this is gonna start weakening. SST's remain above 27C for the forecast period, which should keep it at Cat 4 in the little shear zone this storm is in. Yet the statistical guidance weakens this quite a bit which makes ery little sense.

[Yellow Evan]

The intensity forecast is subject to a big change now considering that the CPAC is in play now in terms of track. The CPAC has warmer than average waters and decreased shear + increased instability. It will head over cooler waters later than projected.

That too could give this storm more time.

[Yellow Evan]

It's acting as if the ERC is done, but it's in no way done per microwave.

[Cyclenall]

Not a very good start to an ERC.

That's certainly right, I don't know what this thing is doing with its ERC. Its delayed on traditional imagery.

What is GCOM W1? Looks like F15 or F18.

[cycloneye]

HURRICANE JIMENA DISCUSSION NUMBER 14
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132015
800 PM PDT SAT AUG 29 2015

Jimena continues to undergo an eyewall replacement, with significant
inner-core structural changes seen in satellite data throughout
the day. Microwave images show a small inner eyewall rotating
around an irregularly-shaped outer eyewall at about 60 n mi radius,
the latter which could be slowly contracting. Although Jimena's
cloud pattern has fluctuated some during this period of inner-core
change, its overall organization has remained about the same
since the last advisory. Satellite classifications seem to bear
this out, with intensity estimates of T6.0/115 kt and T6.5/127 kt
from SAB and TAFB, respectively, at 0000 UTC. These are blended
with the latest UW-CIMSS ADT value of 6.1/117 kt to keep the initial
intensity estimate at 120 kt.

The intensity forecast is challenging. The large-scale environment
is forecast to remain relatively favorable during the next day or
two, apart from some north-northwesterly shear associated with a
cold low to the northeast of Jimena. This could allow an
opportunity for reintensification if the current eyewall
replacement fully plays out, but predicting intensity fluctuations
due to inner-core dynamics is nearly impossible and beyond the
scope of this forecast. Thus, a slow decrease in intensity is
indicated in the new forecast as large-scale conditions only
gradually become less conducive. This is a blend of the
statistical-dynamical guidance. As Jimena gradually gains latitude
later in the forecast period, global models show a minor increase in
westerly shear while other thermodynamic factor remain generally
neutral, except for slowly decreasing SSTs. These factors suggests
a slow decay of the cyclone, and the new intensity forecast is in
agreement with the latest multi-model consensus that shows a
monotonic decrease in intensity from days 3 to 5.

The eye of Jimena has been wobbling quite a bit, but smoothing
through these yields a faster initial motion estimate of 295/11.
Jimena should continue moving west-northwestward during the next few
days as it approaches the western end of a subtropical ridge around
140W. A weakness in the ridge around this longitude should induce a
significant deceleration by days 4 and 5. The track guidance is in
excellent agreement through the first 2 days, with less-than-typical
spread beyond that time. The new track forecast is faster and
adjusted slightly southward and then westward after day 3, but not
as far south or west as the multi-model consensus.


FORECAST POSITIONS AND MAX WINDS

INIT 30/0300Z 13.3N 127.5W 120 KT 140 MPH
12H 30/1200Z 13.9N 129.3W 115 KT 130 MPH
24H 31/0000Z 14.7N 131.8W 110 KT 125 MPH
36H 31/1200Z 15.4N 134.4W 110 KT 125 MPH
48H 01/0000Z 16.0N 136.7W 105 KT 120 MPH
72H 02/0000Z 16.9N 139.9W 95 KT 110 MPH
96H 03/0000Z 17.6N 141.9W 85 KT 100 MPH
120H 04/0000Z 18.1N 143.4W 75 KT 85 MPH

$$
Forecaster Kimberlain

NNNN

[Yellow Evan]

I really don't like the NHC long-range intensity forecast. Most global models keep this well intact for several days.

[terstorm1012]

when will this recurve? I'm pretty interested in that right now

[Yellow Evan]

when will this recurve? I'm pretty interested in that right now

Originally I was thinking sharp re-curve but Ignacio going north may weaken the ridge earlier, giving it time to re-build more.

[Kingarabian]

when will this recurve? I'm pretty interested in that right now

Recurving is in question right now since the last Euro run didn't recurve it all.

GFS is running so we'll see.

[HURAKAN]

[Alyono]

may have upwelling issues from Ignacio

[Kingarabian]

00z GFS takes into Canada in 360 hours.

[wxmann_91]

may have upwelling issues from Ignacio

Or even from slowing down as the models have indicated in around 5 days. Circulation's getting bigger and heat content getting lower around that time as well.

[Extratropical94]

EP, 13, 2015083006, , BEST, 0, 134N, 1278W, 120, 945, HU

[1900hurricane]

Eyewall replacement appears to be making good progress. It's probably not too long before the inner eyewall starts collapsing into the eye now.

[1900hurricane]

Well, not exactly the structure I was expecting to see...