EPAC: SANDRA - Post-Tropical

[Yellow Evan]

I'd like to point out that HURDAt is probs wrong, and in that in reality, this isn't the latest EPAC MH on record.





Hurricane Winnie in 1983.

[CrazyC83]

I'd like to point out that HURDAt is probs wrong, and in that in reality, this isn't the latest EPAC MH on record.





Hurricane Winnie in 1983.

That looks like a solid Cat 3 at least there. T5.5 on Winnie at least.

[CrazyC83]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.2.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 27 NOV 2015 Time : 021500 UTC
Lat : 17:49:48 N Lon : 109:39:59 W


CI# /Pressure/ Vmax
6.8 / 928.0mb/134.8kt


Final T# Adj T# Raw T#
6.8 6.9 7.2

[Cyclenall]

Look at that perfect symmetry and beautiful small eye. Wow!

Yeah I was going to post that frame from the RBTOP...beautiful and different. The southern part of the outflow is unique.

NHC keeps it at 105 kt. Probably believes this is temporary and lends itself to the T5.0/5.5 there.

NRL had this at 110 knots eariler at least.

Going back on that point, even 2005 didn't have a November major in the Atlantic, let alone this late in the month. There has never been a major hurricane after Thanksgiving in the Atlantic, at least in the satellite era.

That's a good point, never thought of that. The Epac season ends earlier than the Atlantic one which makes this hurricane even more outrageous in its high intensity.

Yeah Beven likes to be on the safe side. Would've helped the ACE some if they bumped it up. Let's see if Sandra can still keep it up.

Recon can't get in there fast enough.

HURRICANE SANDRA DISCUSSION NUMBER 14
NWS NATIONAL HURRICANE CENTER MIAMI FL EP222015
800 PM MST THU NOV 26 2015

Despite the presence of at least 25 kt of southwesterly vertical
wind shear, the satellite appearance of Sandra unexpectedly improved
near 0000 UTC when the eye became better defined. Whatever
re-intensification this represents has ended, however, as the eye
has again begun to lose definition. The initial intensity will be
held at 105 kt for this advisory, and the hurricane could have been
a little stronger than that three hours ago based on satellite
intensity estimates.

If a hurricane peaks between advisories, what protects the value of peak intensity accuracy in the books?

I'd like to point out that HURDAt is probs wrong, and in that in reality, this isn't the latest EPAC MH on record.

Hurricane Winnie in 1983.

Does the word this refer to Sandra or Winnie? That "Winnie" doesn't look like a MH.

[Yellow Evan]

That image above is Winnie (it's from HURSAT) and is a clear T6.0. LG eye surrounded by W embedded in W is T6.0.

Also if a hurricane peaks between advisories, NHC could insert a special time to put in the ATCF like they do for landfalls.

[EquusStorm]

Honestly I really hope we DO get a Winnie-like system this year to top off the incredible season. At this rate I would not be shocked if we actually did get an early December system with the way the overall pattern seems to favor this fall... though I don't know if any models even hint of even the possibility of such right now.

Sandra's second wind was unexpected and impressive. Maybe the first structural collapse was the result of an ERC and not shear?

[Yellow Evan]

Microwave doesn't suggest an outer eywall, but it could have ERC'd between microwave passes.

[wxmann_91]

Honestly I really hope we DO get a Winnie-like system this year to top off the incredible season. At this rate I would not be shocked if we actually did get an early December system with the way the overall pattern seems to favor this fall... though I don't know if any models even hint of even the possibility of such right now.

Sandra's second wind was unexpected and impressive. Maybe the first structural collapse was the result of an ERC and not shear?

I personally thought it looked more like an ERC... shear didn't really get to Sandra's core until the past few hours.

[Kingarabian]

3 ACE units away from the record.

[cycloneye]

HURRICANE SANDRA DISCUSSION NUMBER 15
NWS NATIONAL HURRICANE CENTER MIAMI FL EP222015
200 AM MST FRI NOV 27 2015

It appears that the strong shear is finally affecting the structure
of the hurricane. The cloud pattern has rapidly deteriorated and the
eye is no longer observed. In fact, most of the deep convection is
now on the northeastern portion of the cyclone. Both objective and
subjective numbers are decreasing, and the initial intensity has
been lowered to 90 kt. The shear is forecast to increase even more,
and most of the global models continue to separate the surface
center from the mid-level circulation. As suggested by guidance, the
NHC forecast calls for weakening and brings Sandra near the coast of
mainland Mexico below tropical storm strength.

Satellite fixes indicate that Sandra has been moving toward the
north-northeast of 020 degrees at 10 kt. The cyclone is already
embedded within the broad southwesterly flow ahead of a large
mid-latitude trough, and no significant change in the steering
pattern is anticipated. On this basis, the NHC forecast keeps this
general motion until the center of the cyclone reaches the coast of
Mexico in about 36 hours. The NHC forecast is a little bit east of
the previous one, and is basically on top of the multi-model
consensus. The ECMWF model has shifted a little bit eastward
in the last run, but still is on the western edge of dynamical
guidance envelope.

Given the eastward shift in the forecast track, the expected
weakening, and the likely decay of the wind field to the west of
the center, it is becoming less likely that a tropical storm warning
will be required for southern the Baja California peninsula later
this morning.

Regardless of the intensity of Sandra, heavy rains over portions of
Mexico, the remnant mid-/upper-level moisture associated with
the cyclone will contribute to a significant precipitation event
expected to occur over portions of the south-central United States
this weekend. For more information on this event, please see
products from the NOAA Weather Prediction Center and local NWS
Weather Forecast Offices.


FORECAST POSITIONS AND MAX WINDS

INIT 27/0900Z 18.9N 109.3W 90 KT 105 MPH
12H 27/1800Z 20.5N 108.8W 70 KT 80 MPH
24H 28/0600Z 22.3N 108.3W 45 KT 50 MPH
36H 28/1800Z 24.2N 108.0W 30 KT 35 MPH
48H 29/0600Z 26.5N 107.5W 20 KT 25 MPH...POST-TROP/INLAND
72H 30/0600Z...DISSIPATED

$$
Forecaster Avila

[tolakram]

Looks to be moving east of the track, or is in the process of being sheared apart.

Live IR
http://wwwghcc.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-W%20PACUS&lat=15&lon=-100&info=ir&zoom=2&width=1000&height=800&type=Animation&quality=85&palette=ir2.pal&numframes=14

[cycloneye]

HURRICANE SANDRA DISCUSSION NUMBER 16
NWS NATIONAL HURRICANE CENTER MIAMI FL EP222015
800 AM MST FRI NOV 27 2015

The coverage of cold cloud tops within the CDO of Sandra continues
to decrease, and the southwestern portion of the CDO has eroded due
to about 30 kt of southwesterly shear. An 1133Z SSMIS image also
showed that the eye had become less distinct. Dvorak intensity
estimates continue to decrease, and based on a blend of the latest
Final-T and CI numbers the initial intensity has been lowered to 85
kt, and this could be a bit generous. Quick weakening is expected
during the next 24 hours as the shear is forecast to increase to 40
to 45 kt. This should result in the low-level circulation of Sandra
decoupling from the mid-level circulation before it reaches the
coast. Sandra is forecast to weaken to a tropical storm later today
and continue to weaken as it approaches the coast of Mexico in about
24 hours, but is still expected to be a tropical storm. After
landfall, the low-level circulation should quickly dissipate,
although a 36-hour forecast point was provided to show the system
moving inland. The new NHC intensity forecast is close to a blend of
the HWRF, SHIPS and LGEM models.

Sandra has moved to the right of the previous forecast track, and
the initial motion estimate is 030/10. Sandra should continue to
recurve between a mid-level ridge centered over the western Gulf of
Mexico and a broad deep-layer trough over western North America.
Given the initial motion, the new NHC track forecast has been
adjusted to the right of the previous one and now lies to the right
of the latest multi-model consensus. The official forecast favors
the GFS and HWRF models, which have the best handle on the initial
motion. This adjustment to the track will bring the center of Sandra
to the coast of Mexico in about 24 hours.

Given the eastward shift in the forecast track and the expectation
that Sandra will still be a tropical storm as it nears the coast,
the Government of Mexico has issued a tropical storm warning for Las
Islas Marias and part of the coasts of the states of Sinaloa and
Nayarit. Regardless of Sandra's intensity at landfall, the main
threat will be heavy rains across portions of several Mexican
states.

The remnant mid- and upper-level moisture associated with Sandra
will contribute to a significant precipitation event expected to
occur over portions of the south-central United States this weekend.
For more information, please see products from the NOAA Weather
Prediction Center and local NWS Weather Forecast Offices.

FORECAST POSITIONS AND MAX WINDS

INIT 27/1500Z 19.6N 108.4W 85 KT 100 MPH
12H 28/0000Z 21.4N 107.7W 60 KT 70 MPH
24H 28/1200Z 23.5N 106.7W 40 KT 45 MPH
36H 29/0000Z 25.8N 105.0W 20 KT 25 MPH...POST-TROP/INLAND
48H 29/1200Z...DISSIPATED

$$
Forecaster Brennan

[WeatherGuesser]

3 ACE units away from the record.

So, it's a done deal because it isn't about to die that quickly. Bound to be good for 5 or ....

[EquusStorm]

Plus, post-season changes might increase Sandra's intensity on its second wind, so even if we don't break the ACE record, if we're really close, it's not impossible we could push just over it.

[Yellow Evan]

3 ACE units away from the record.

So, it's a done deal because it isn't about to die that quickly. Bound to be good for 5 or ....

This storm probs has 3 ACE units left.

[Ntxw]

Plus, post-season changes might increase Sandra's intensity on its second wind, so even if we don't break the ACE record, if we're really close, it's not impossible we could push just over it.

In addition to some others that may get bumped up. Critical if the ACE is that close with 1992.

Personal note I hope it does beat out. With the show EPAC has put on this is a record 2015 is deserving of

[Yellow Evan]

ACE goes down in post-season usually since the NHC goes higher than the ATCF more often than lower.

[Kingarabian]

I think we definitely surpassed 1992 this year in ACE. Couple of storms this year that were undervalued in intensity. The CPHC also took its time assigning correct intensity updates on certain storms as well (but they improved considerably later on in the season)

[Yellow Evan]

Only storms that were underestimated were Niala and Kevin. Maybe Oho. The rest looked about right to me.

Tbh, 1992 was in the era where CI values were hugged more often and ADT was too bullish for weakening system, so if that season were to take place today, the ACE may be slightly lower (even though a few off the storms were def a bit underestimated at peak).

[cycloneye]

HURRICANE SANDRA DISCUSSION NUMBER 17
NWS NATIONAL HURRICANE CENTER MIAMI FL EP222015
200 PM MST FRI NOV 27 2015

Geostationary and microwave imagery indicate that the low-level
center of Sandra has begun to separate from the mid-level
circulation. This is due to vertical shear of 30 to 35 kt, which is
forecast to increase further tonight. Dvorak estimates continue to
decrease as the deep convection wanes and separates from the center,
and the initial intensity has been conservatively lowered to 70 kt
based on a blend of the latest Final-T and CI numbers from TAFB and
SAB. Quick weakening is forecast, and Sandra should weaken to a
tropical storm in the next 12 hours and become a tropical depression
or remnant low in 24-36 hours before dissipating. The new NHC
intensity forecast is close to the latest SHIPS model.

The low-level center has wobbled to the left during the past couple
of hours, but a long-term initial motion estimate is 020/09. As
Sandra shears apart, the guidance envelope has shifted to the left
this cycle, with the exception of the HWRF. The new NHC track has
been adjusted a little to the left of the previous one now that the
cyclone is starting to weaken more quickly, and the NHC forecast is
close to the latest ECMWF solution. If Sandra decouples faster than
anticipated, the low-level circulation could move to the left of
the new forecast track and even dissipate entirely before the center
reaches the coast. However, the main threat of heavy rainfall over a
large part of west-central Mexico will occur regardless of the
details of the track and intensity forecast.

The remnant mid- and upper-level moisture associated with Sandra
will contribute to a significant precipitation event expected to
occur over portions of the south-central United States this weekend.
For more information, please see products from the NOAA Weather
Prediction Center and local NWS Weather Forecast Offices.

FORECAST POSITIONS AND MAX WINDS

INIT 27/2100Z 20.4N 108.4W 70 KT 80 MPH
12H 28/0600Z 22.1N 107.8W 50 KT 60 MPH
24H 28/1800Z 23.8N 107.2W 30 KT 35 MPH
36H 29/0600Z 25.5N 106.6W 20 KT 25 MPH...POST-TROP/INLAND
48H 29/1800Z...DISSIPATED

$$
Forecaster Brennan