EPAC: KEVIN - Post-Tropical

[TheAustinMan]

Looking particularly impressive this morning. That could actually be a developing eye on what is currently classified as a minimal tropical storm:

[Yellow Evan]

TAM, looks to be a mid-level eye; AMSU pass (low-reS) wasn't too impressive.

Probs worthy of a T3.0 right now via CDO shear pattern.

[Yellow Evan]

Old disco since that never got posted:

000
WTPZ44 KNHC 030846
TCDEP4

TROPICAL STORM KEVIN DISCUSSION NUMBER 11
NWS NATIONAL HURRICANE CENTER MIAMI FL EP142015
200 AM PDT THU SEP 03 2015

Recent ASCAT data indicate that the cyclone is producing a sizable
area of 35-kt winds, especially beneath a burst of deep convection
which has persisted during the past few hours. The scatterometer
data also indicated that the low-level center is now embedded
beneath the southeastern edge of the convective canopy, and Dvorak
estimates are a consensus T2.5/35 kt from TAFB and SAB. Based on
these data, the cyclone is being upgraded to Tropical Storm Kevin.
Although some southerly shear is expected to continue affecting
Kevin during the next several days, warm sea surface temperatures
and a moist environment could support just a little more
strengthening during the next 24 hours. The NHC intensity forecast
has been adjusted slightly upward during that period and shows a
peak intensity close to the ICON intensity consensus and the Florida
State Superensemble. After 36 hours, the shear is likely to allow
drier air to get into the circulation, leading to weakening. Kevin
is forecast to degenerate to a remnant low by day 3 and dissipate
around day 5.

With the help of the ASCAT data, the low-level center was adjusted
a tad west of where it was previously estimated, and the initial
motion estimate is 350/5 kt. Kevin should continue northward
between a mid-level anticyclone over Mexico and a deep-layer trough
off the west coast of North America for the next 36 hours. Once the
cyclone weakens and is no longer producing significant deep
convection, the center is expected to turn westward in the low-level
flow. The global models appear to be in better agreement on when
this turn will occur, and the bulk of the guidance now shows a
sharper westward turn after 48 hours. The new NHC track forecast is
therefore a bit west of the previous forecast and is close to the
TVCE dynamical consensus.

FORECAST POSITIONS AND MAX WINDS

INIT 03/0900Z 17.5N 115.3W 35 KT 40 MPH
12H 03/1800Z 18.4N 115.5W 40 KT 45 MPH
24H 04/0600Z 19.6N 115.5W 40 KT 45 MPH
36H 04/1800Z 20.6N 115.4W 35 KT 40 MPH
48H 05/0600Z 21.3N 115.6W 30 KT 35 MPH
72H 06/0600Z 22.1N 117.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 07/0600Z 22.1N 119.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 08/0600Z...DISSIPATED

$$
Forecaster Berg


Current ADT:

Code: Select all

----- Current Analysis -----
     Date :  03 SEP 2015    Time :   120000 UTC
      Lat :   17:47:55 N     Lon :  115:21:14 W

     
                CI# /Pressure/ Vmax
                3.0 / 999.7mb/ 45.0kt

     
             Final T#  Adj T#  Raw T#
                3.0     3.1     3.5

 Center Temp : -75.6C    Cloud Region Temp : -65.4C

 Scene Type : IRREGULAR CDO*

[Yellow Evan]

03/1200 UTC 17.9N 115.8W T3.0/3.0 KEVIN -- East Pacific

[Yellow Evan]

TAFB:

EP, 14, 201509031200, 10, DVTS, CI, , 1760N, 11570W, , 3, 45, 2, 1000, 2, DVRK, , , , , , , , , , , , , , E, TAFB, MF, I, 5, 3030 /////, , , GOES15, CSC, T,


NHC up to 45:

EP, 14, 2015090312, , BEST, 0, 176N, 1156W, 45, 1000, TS, 34, NEQ, 60, 30, 30, 60, 1009, 180, 30, 0, 0, E, 0, , 0, 0, KEVIN, M, 0, , 0, 0, 0, 0, genesis-num, 022,

[1900hurricane]

The warm spot looks like an enhanced V signature that is sometimes seen with the overshooting tops of severe thunderstorms to me.

[cycloneye]

TROPICAL STORM KEVIN DISCUSSION NUMBER 12
NWS NATIONAL HURRICANE CENTER MIAMI FL EP142015
800 AM PDT THU SEP 03 2015

Kevin has been producing bursts of cold-topped convection this
morning, although banding features are limited. The latest Dvorak
intensity estimates from both TAFB and SAB are at 45 kt, and this
will be used for the advisory intensity. The storm is in an
environment of moderate south-southwesterly shear, which should
prevent significant additional strengthening. However a bit more
intensification could occur, as indicated in the official forecast.
In a day or so, Kevin is likely to be ingesting drier and more
stable mid-level air and that, along with the shear, should lead to
a weakening trend. The official intensity forecast is similar to
the latest intensity model consensus.

The center is difficult to locate on geostationary satellite images,
and the initial motion is an uncertain 350/5. Over the next couple
of days, Kevin should turn toward the northwest while it moves to
the southwest of a mid-level anticyclone. Afterwards, the weakening
and increasingly shallow cyclone should turn westward following the
low-level steering flow. The official track forecast is nudged a
bit to the west of the previous one. This is close to the latest
dynamical model consensus, albeit a little slower in the latter part
of the forecast period.

FORECAST POSITIONS AND MAX WINDS

INIT 03/1500Z 17.9N 115.6W 45 KT 50 MPH
12H 04/0000Z 18.8N 115.7W 50 KT 60 MPH
24H 04/1200Z 19.9N 115.8W 50 KT 60 MPH
36H 05/0000Z 20.9N 116.0W 45 KT 50 MPH
48H 05/1200Z 21.5N 116.5W 40 KT 45 MPH
72H 06/1200Z 22.1N 118.2W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 07/1200Z 22.2N 120.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 08/1200Z...DISSIPATED

$$
Forecaster Pasch

[Yellow Evan]

03/1800 UTC 18.3N 115.9W T3.5/3.5 KEVIN -- East Pacific

[Kingarabian]

Has an decent shot @ hurricane status IMO.

[Yellow Evan]

----- Current Analysis -----
Date : 03 SEP 2015 Time : 173000 UTC
Lat : 18:09:08 N Lon : 115:37:09 W


CI# /Pressure/ Vmax
3.6 / 991.9mb/ 57.0kt


Final T# Adj T# Raw T#
3.6 3.7 3.9

Center Temp : -73.6C Cloud Region Temp : -68.7C

[Yellow Evan]

EP, 14, 2015090318, , BEST, 0, 184N, 1158W, 45, 1000, TS, 34, NEQ, 60, 30, 30, 60, 1009, 180, 30, 0, 0, E, 0, , 0, 0, KEVIN, M, 0, , 0, 0, 0, 0, genesis-num, 022,

[galaxy401]

Best Track seems to low with the recent Dvorak numbers.

[Yellow Evan]

Best Track seems to low with the recent Dvorak numbers.

ADt is 3.6 (should be at 3.7 on next fix), SAB is 3.5, and TAFB is 3.0. Supports 50-55.

[cycloneye]

TROPICAL STORM KEVIN DISCUSSION NUMBER 13
NWS NATIONAL HURRICANE CENTER MIAMI FL EP142015
200 PM PDT THU SEP 03 2015

The intensity and coverage of deep convection being produced by
Kevin has been decreasing, although this may be a diurnal
fluctuation. There are some ill-defined banding features over the
northern semicircle, and the cyclone still has some outflow over
the southern part of the circulation. The latter is a bit
surprising, given the south-southwesterly shear over the system.
The current intensity is held at 45 kt which is consistent with the
latest Dvorak estimate from TAFB. There is a narrow window of
opportunity for intensification in the short term, i.e. during the
next 12 to 24 hours. Thereafter, the shear is forecast to increase
and the cyclone should be ingesting drier and more stable air. The
official forecast shows slight strengthening overnight followed by
weakening and eventual degeneration into a remnant low in about 3
days. This is very close to the latest model consensus. Some of
the guidance, such as the SHIPS model, show an even faster weakening
than indicated here.

Recent microwave imagery has provided some good center fixes, and
the initial motion is a slightly faster 360/7. Kevin should move
northward to northwestward on the southwest side of a mid-level
subtropical anticyclone for the next day or two. Afterward, the
weakening and increasingly shallow cyclone is likely to turn toward
the west and be steered mainly by the low-level flow. The GFDL and
HWRF models show a much more northward track, and appear to be
unrealistic. The official track forecast is similar to the previous
one, and close to the latest ECMWF solution.

FORECAST POSITIONS AND MAX WINDS

INIT 03/2100Z 18.7N 115.8W 45 KT 50 MPH
12H 04/0600Z 19.8N 115.8W 50 KT 60 MPH
24H 04/1800Z 21.2N 115.8W 50 KT 60 MPH
36H 05/0600Z 22.0N 116.3W 45 KT 50 MPH
48H 05/1800Z 22.3N 117.1W 40 KT 45 MPH
72H 06/1800Z 22.5N 119.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 07/1800Z 22.5N 121.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 08/1800Z...DISSIPATED

$$
Forecaster Pasch

[galaxy401]

TROPICAL STORM KEVIN DISCUSSION NUMBER 14
NWS NATIONAL HURRICANE CENTER MIAMI FL EP142015
800 PM PDT THU SEP 03 2015

Intense thunderstorms have been persisting near the center of Kevin
during the past several hours, with outflow continuing especially
in the cyclone's northern semicircle. Microwave data also show that
the inner core of the storm is better defined than earlier today.
The initial intensity is thus increased to 50 kt, a blend of the 45
kt classification from TAFB and the 55 kt one from SAB. The cyclone
should reach its peak intensity in the next 12 hours or so while the
shear remains low-to-moderate and waters are warm. Thereafter, the
shear is forecast to strengthen and Kevin will encounter more
marginal SSTs and dry mid-level air, which should cause weakening.
The official forecast is a blend of the previous forecast and the
intensity consensus. Degeneration into a remnant low in expected
about 3 days due to a continuation of the higher shear, low moisture
and cool water environment.

Kevin is moving a little faster tonight, estimated at 360/8. Over
the next day or so, while the system remains vertically intact, it
should move generally northward around the southwest side of a mid-
level ridge. Afterward, the weakening and increasingly shallow
cyclone is likely to turn toward the northwest and west and be
steered mainly by the low-level flow. Model guidance, however, is
not in good agreement on when this leftward turn will occur, with
almost all of the guidance delaying the turn a bit longer on this
cycle, resulting in Kevin gaining more latitude. Because Kevin has
now become a deeper cyclone, it makes sense to move the new NHC
prediction north of the previous one given that Kevin should now
take a little longer to become a more shallow cyclone. However, the
new forecast still lies south of most of the guidance and the model
consensus.

FORECAST POSITIONS AND MAX WINDS

INIT 04/0300Z 19.7N 115.8W 50 KT 60 MPH
12H 04/1200Z 20.8N 115.8W 50 KT 60 MPH
24H 05/0000Z 22.0N 115.9W 45 KT 50 MPH
36H 05/1200Z 22.7N 116.5W 40 KT 45 MPH
48H 06/0000Z 23.3N 117.3W 30 KT 35 MPH
72H 07/0000Z 23.5N 119.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 08/0000Z...DISSIPATED

$$
Forecaster Blake

[1900hurricane]

Kevin is still firing convection very vigorously (and is quite round).

[Yellow Evan]

Idk why ADT isn't being factored in here.

Dvorak doesn't do well with these kinds of storms. There's a decent microwave presenation as well (though not as good as earlier). While I get the sense that Kevin is about to fall apart, I think 60 knts is a good estimate, maybe 55 knots. I'm honestly disappointed in the NHC today.

[Yellow Evan]

----- Current Analysis -----
Date : 04 SEP 2015 Time : 033000 UTC
Lat : 19:45:54 N Lon : 115:47:59 W


CI# /Pressure/ Vmax
4.0 / 985.8mb/ 65.0kt


Final T# Adj T# Raw T#
4.0 4.3 4.3

Center Temp : -72.6C Cloud Region Temp : -74.1C

Scene Type : UNIFORM CDO CLOUD REGION

[Yellow Evan]

ZCZC MIATCDEP4 ALL
TTAA00 KNHC DDHHMM

TROPICAL STORM KEVIN DISCUSSION NUMBER 15
NWS NATIONAL HURRICANE CENTER MIAMI FL EP142015
200 AM PDT FRI SEP 04 2015

Kevin continues to produce a cluster of convection near the center
with cloud tops colder than -80C. However, cirrus cloud motions in
infrared satellite imagery suggest that southerly vertical wind
shear is increasing over the cyclone, and an AMSU overpass at 0458
UTC suggests the low-level center is near the southern edge of the
convection. The initial intensity remains 50 kt based on a blend
of intensity estimates from TAFB, SAB, and the CIMSS satellite
consensus technique.

The initial motion is 360/7. Kevin should move generally northward
for the next 12-24 hours. After that time, the dynamical guidance
suggests that the top and the bottom of the cyclone will part
company, with the mid- to upper-level center continuing northward
and the low-level center turning northwestward and then
west-northwestward. The new forecast track is similar to the
previous track through 48 hours and lies near the various consensus
models. After that time, it is nudged a little northward due to a
northward shift in the track guidance.

The forecast track takes Kevin over decreasing sea surface
temperatures in an environment of increasing shear. This
combination should cause steady weakening after 12 hours, with Kevin
forecast to weaken to a depression in about 36 hours an to
degenerate to a remnant low shortly thereafter. The new intensity
forecast is in best agreement with the intensity consensus models.


FORECAST POSITIONS AND MAX WINDS

INIT 04/0900Z 20.2N 115.8W 50 KT 60 MPH
12H 04/1800Z 21.2N 115.8W 50 KT 60 MPH
24H 05/0600Z 22.2N 116.1W 40 KT 45 MPH
36H 05/1800Z 22.9N 116.8W 30 KT 35 MPH
48H 06/0600Z 23.4N 117.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 07/0600Z 24.0N 120.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 08/0600Z...DISSIPATED

$$
Forecaster Beven

[Yellow Evan]

000
WTPZ44 KNHC 041454
TCDEP4

TROPICAL STORM KEVIN DISCUSSION NUMBER 16
NWS NATIONAL HURRICANE CENTER MIAMI FL EP142015
800 AM PDT FRI SEP 04 2015

Kevin's cloud pattern consists of a large circular mass of very deep
convection, with the low- to mid-level centers nearly co-located as
of several hours. Since that time, satellite data indicate that the
cyclone has begun the process of decoupling due to the 25 kt of
south-southwesterly vertical shear affecting it. Although Dvorak
intensity estimates were T3.5/55 kt from TAFB and SAB at 1200 UTC,
the initial wind speed is kept at 50 kt due to the weakening that
has likely begun.

Even stronger shear associated with a potent mid- to upper-level
trough to the northwest of Kevin should result in a complete
separation of the cyclone's low- to mid-level circulations within 24
hours, according to global models. Substantially drier air behind
the trough should also be entrained by the cyclone, which should
cause a collapse of deep convection during the next or so. Global
models depict Kevin becoming a remnant low in about 36 hours and
show dissipation by 72 hours. The new intensity forecast shows
faster weakening than the previous one, with remnant low status and
dissipation also indicated sooner.

Based on fixes from a series of microwave passes overnight, the
cyclone has been moving a little east of due north, and the initial
motion estimate is 010/07. Kevin should turn due north soon when
the trough to its northwest sinks southward. As Kevin decouples
during the next 24 hours, a deceleration is forecast by the model
guidance. A bend in the track toward the northwest and west-
northwest is also anticipated during this time, when Kevin meets
the opposing flow around the low-level subtropical ridge over the
eastern Pacific. The new track forecast is on the right side of the
guidance envelope at first, primarily due to the north-northeasterly
motion overnight but is shifted a bit southward once Kevin becomes a
remnant low.


FORECAST POSITIONS AND MAX WINDS

INIT 04/1500Z 21.2N 115.2W 50 KT 60 MPH
12H 05/0000Z 22.1N 115.4W 45 KT 50 MPH
24H 05/1200Z 22.9N 116.0W 35 KT 40 MPH
36H 06/0000Z 23.3N 116.9W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 06/1200Z 23.4N 118.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 07/1200Z...DISSIPATED

$$
Forecaster Kimberlain