EPAC: KEVIN - Post-Tropical

[Nancy Smar]

EP112021 - Tropical Depression ELEVEN

ep112021 2021-08-07 12:00 15.8 -105.1 30

[aspen]

Maybe Kevin could become a Cat 1, but not even the HWRF is particularly thrilled. It doesn’t seem like it’ll have that good of a structure.

[cycloneye]

BULLETIN
Tropical Depression Eleven-E Advisory Number 1
NWS National Hurricane Center Miami FL EP112021
1000 AM CDT Sat Aug 07 2021

...NEW TROPICAL DEPRESSION FORMS OFFSHORE THE SOUTHWESTERN COAST OF
MEXICO...


SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...15.9N 105.5W
ABOUT 230 MI...365 KM SSW OF MANZANILLO MEXICO
ABOUT 560 MI...905 KM SSE OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 275 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES


Tropical Depression Eleven-E Discussion Number 1
NWS National Hurricane Center Miami FL EP112021
1000 AM CDT Sat Aug 07 2021

Last night's METOP-A/B scatterometer overpasses indicated that the
area of low pressure located a couple hundred miles south-southwest
of Manzanillo, Mexico had become a little better defined, and
since that time, the system has developed sufficient organized
convection to be designated as a tropical depression. The initial
intensity is estimated to be 30 kt and is in agreement with the
satellite intensity estimates from TAFB and SAB.

Modest northeasterly shear, warm sea surface temperatures and
a moist surrounding low- to mid-level environment support steady
strengthening during the next few days, and the depression
is forecast to become a tropical storm by tonight. The Statistical
SHIPS (GFS/ECMWF), and the HCCA/IVCN multi-model intensity aids,
all show that the cyclone will become a hurricane in about 48
hours, and the NHC forecast follows suit. The intensity forecast
resembles the HCCA and IVCN intensity consensus models, and is just
below the Decay SHIPS guidance.

The initial motion is estimated to be westward, or 275/8 kt. The
depression is being steered by a mid-tropospheric ridge stretching
westward over the subtropical eastern Pacific from high pressure
located over the northern Gulf of Mexico. A general westward motion
with a similar forward speed is expected through early next week.
Through the remaining portion of the forecast, a turn toward the
west-northwest to northwest is expected due to a growing weakness in
the aforementioned ridge. The official forecast is based on the
TVCN multi-model consensus and lies between the GFS and ECMWF global
models solutions.



FORECAST POSITIONS AND MAX WINDS

INIT 07/1500Z 15.9N 105.5W 30 KT 35 MPH
12H 08/0000Z 15.9N 106.8W 40 KT 45 MPH
24H 08/1200Z 15.9N 108.4W 45 KT 50 MPH
36H 09/0000Z 15.9N 109.7W 55 KT 65 MPH
48H 09/1200Z 16.2N 111.1W 65 KT 75 MPH
60H 10/0000Z 16.8N 112.3W 70 KT 80 MPH
72H 10/1200Z 18.0N 113.7W 70 KT 80 MPH
96H 11/1200Z 19.9N 117.3W 65 KT 75 MPH
120H 12/1200Z 21.7N 121.4W 50 KT 60 MPH

$$
Forecaster Roberts

[Kingarabian]

This thing is massive compared to what we've seen so far.

[Sciencerocks]

[Yellow Evan]

12z GFS has the vorticity interacting with the monsoon trough for another 2-3 days.

[Category5Kaiju]

Maybe Kevin could become a Cat 1, but not even the HWRF is particularly thrilled. It doesn’t seem like it’ll have that good of a structure.

If the HWRF isn't thrilled, then you know it won't amount to much

In seriousness though, we'll see though, sometimes these systems can really overperform or underperform contrary to such kinds of models. Although my hunch is future Kevin won't really blow up into anything eye-popping

[Yellow Evan]

TXPZ22 KNES 071755
TCSENP

A. 11E (NONAME)

B. 07/1730Z

C. 16.0N

D. 105.9W

E. FIVE/GOES-E

F. T2.5/2.5

G. IR/EIR/VIS

H. REMARKS...SYSTEM HAS 4.5/10 BANDING RESULTING IN A DT OF 2.5. THE 24
HR DEVELOPING TREND RESULTS IN DEVELOPING. MET IS 2.0 AND PT IS 2.5. FT
IS BASED ON DT.

I. ADDL POSITIONS

NIL


...PATEL

[ElectricStorm]

Hello Kevin
11E ELEVEN 210807 1800 15.8N 106.3W EPAC 35 1005

[Yellow Evan]

* GFS version *
* EAST PACIFIC 2021 SHIPS INTENSITY FORECAST *
* IR SAT DATA AVAILABLE, OHC AVAILABLE *
* ELEVEN EP112021 08/07/21 18 UTC *

TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120 132 144 156 168
V (KT) NO LAND 35 41 48 54 61 70 78 79 82 81 72 62 54 46 40 33 27
V (KT) LAND 35 41 48 54 61 70 78 79 82 81 72 62 54 46 40 33 27
V (KT) LGEM 35 40 45 49 54 61 66 67 67 65 57 48 39 32 25 20 16
Storm Type TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP

SHEAR (KT) 10 12 15 19 19 16 26 22 14 17 20 13 11 10 9 5 3
SHEAR ADJ (KT) -2 -2 -4 -1 1 0 3 2 -3 1 1 -1 0 1 0 0 -3
SHEAR DIR 50 59 57 60 65 59 55 41 27 67 55 36 21 38 23 42 5
SST (C) 29.0 29.0 29.1 29.2 29.2 29.0 28.6 28.1 28.2 26.8 25.9 25.1 23.4 22.7 22.2 21.8 20.8
POT. INT. (KT) 154 154 155 155 155 153 149 145 146 132 122 114 97 89 84 81 71
200 MB T (C) -53.4 -52.8 -53.1 -53.3 -53.0 -52.6 -52.2 -51.5 -51.1 -51.0 -51.3 -51.2 -51.4 -51.3 -51.7 -51.7 -51.9
200 MB VXT (C) 0.0 0.1 0.2 0.4 0.4 0.4 0.5 0.6 0.8 0.8 0.5 0.3 0.6 0.4 0.6 0.2 0.4
TH_E DEV (C) 6 6 5 4 4 4 3 3 2 1 0 0 0 0 0 0 0
700-500 MB RH 83 83 83 84 84 82 83 81 80 74 70 63 58 51 46 41 37
MODEL VTX (KT) 11 12 13 15 18 19 23 24 27 29 28 25 23 20 18 15 12
850 MB ENV VOR 1 13 9 12 17 30 48 47 96 96 114 106 87 75 66 57 33
200 MB DIV 72 102 117 94 112 134 107 123 100 22 9 -10 -31 -9 6 0 4
700-850 TADV 0 0 0 0 0 -5 -11 -22 -15 -7 -6 -8 1 3 -1 5 -2
LAND (KM) 413 450 499 560 624 720 758 711 698 740 832 938 1003 1148 1331 1505 1557
LAT (DEG N) 15.8 15.9 16.0 15.9 15.8 16.0 16.4 17.3 18.7 19.6 20.2 21.1 22.3 xx.x xx.x xx.x xx.x
LONG(DEG W) 106.3 107.2 108.1 108.8 109.5 110.8 112.2 113.3 115.0 116.8 118.7 120.7 122.9 xxx.x xxx.x xxx.x xxx.x
STM SPEED (KT) 9 9 8 7 7 6 7 9 10 10 10 11 11 10 10 14 15
HEAT CONTENT 17 16 16 17 18 15 12 9 9 2 0 0 0 0 0 0 0

FORECAST TRACK FROM OFCI INITIAL HEADING/SPEED (DEG/KT):270/ 10 CX,CY: -9/ 0
T-12 MAX WIND: 25 PRESSURE OF STEERING LEVEL (MB): 444 (MEAN=587)
GOES IR BRIGHTNESS TEMP. STD DEV. 50-200 KM RAD: 11.2 (MEAN=14.5)
% GOES IR PIXELS WITH T < -20 C 50-200 KM RAD: 93.0 (MEAN=65.0)
PRELIM RI PROB (DV .GE. 35 KT IN 36 HR): 42.9

INDIVIDUAL CONTRIBUTIONS TO INTENSITY CHANGE
6 12 18 24 36 48 60 72 84 96 108 120 132 144 156 168
------------------------------------------------------------------------------
SAMPLE MEAN CHANGE 0. 0. 1. 1. 1. 2. 1. 1. 0. -0. -1. -2. -2. -3. -4. -4.
SST POTENTIAL 0. 1. 1. 2. 6. 11. 16. 20. 23. 24. 25. 24. 22. 19. 16. 13.
VERTICAL SHEAR MAG 0. 1. 1. 2. 2. -1. -4. -6. -8. -10. -10. -9. -8. -8. -8. -7.
VERTICAL SHEAR ADJ 0. 1. 1. 1. 1. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
VERTICAL SHEAR DIR 0. 1. 1. 2. 3. 5. 5. 5. 4. 4. 3. 2. 1. 0. -0. -1.
PERSISTENCE 2. 3. 3. 3. 3. 2. 2. 2. 2. 2. 2. 2. 2. 2. 2. 2.
200/250 MB TEMP. 0. 0. -0. -0. -1. -1. -2. -3. -2. -2. -1. -0. 1. 2. 3. 3.
THETA_E EXCESS -0. -0. -0. -1. -2. -2. -3. -5. -6. -7. -8. -9. -10. -11. -13. -16.
700-500 MB RH 0. 0. 1. 1. 2. 2. 2. 2. 2. 2. 2. 2. 2. 3. 3. 3.
MODEL VTX TENDENCY 0. 1. 3. 5. 6. 11. 15. 21. 25. 22. 17. 13. 9. 6. 3. 0.
850 MB ENV VORTICITY -0. -0. -0. -0. -0. 0. 0. -0. -0. -1. -1. -1. -1. -1. -1. -1.
200 MB DIVERGENCE 0. 1. 1. 1. 2. 3. 5. 7. 7. 6. 5. 3. 2. 0. -0. -1.
850-700 T ADVEC -0. -0. -0. -0. -0. -0. -0. -0. -0. -0. -0. -1. -1. -1. -1. -1.
ZONAL STORM MOTION 0. 0. 0. 0. 1. 1. 1. 1. 1. 1. 1. 1. 0. 0. 0. -0.
STEERING LEVEL PRES -0. -0. -1. -1. -2. -2. -2. -2. -2. -3. -3. -3. -2. -2. -2. -1.
DAYS FROM CLIM. PEAK 0. 0. 0. 0. 0. 0. 0. 1. 1. 1. 1. 1. 1. 2. 2. 2.
GOES PREDICTORS 1. 2. 3. 3. 2. 2. 2. 2. 2. 2. 2. 2. 2. 1. 1. 0.
OCEAN HEAT CONTENT -0. -0. -0. -0. -0. -0. -0. -0. -0. -0. 0. 0. 1. 2. 3. 4.
RI POTENTIAL 1. 3. 5. 7. 11. 10. 6. 1. -1. -3. -5. -6. -6. -6. -6. -5.
------------------------------------------------------------------------------
TOTAL CHANGE 6. 13. 19. 26. 35. 43. 44. 47. 46. 37. 27. 19. 11. 5. -2. -8.

CURRENT MAX WIND (KT): 35. LAT, LON: 15.8 106.3

** 2021 E. Pacific RI INDEX EP112021 ELEVEN 08/07/21 18 UTC **
(SHIPS-RII PREDICTOR TABLE for 30 KT OR MORE MAXIMUM WIND INCREASE IN NEXT 24-h)

Predictor Value RI Predictor Range Scaled Value(0-1) % Contribution
POT = MPI-VMAX (KT) : 119.8 40.5 to 149.3 0.73 5.8
12 HR PERSISTENCE (KT) : 10.0 -22.0 to 44.0 0.48 4.4
D200 (10**7s-1) : 99.4 -33.0 to 159.5 0.69 5.1
850-200 MB SHEAR (KT) : 14.9 19.6 to 1.3 0.26 1.8
MAXIMUM WIND (KT) : 35.0 22.5 to 132.0 0.36 2.0
STD DEV OF IR BR TEMP : 11.2 37.8 to 2.1 0.75 3.7
BL DRY-AIR FLUX (W/M2) : 5.2 800.8 to -82.5 0.90 -5.0
HEAT CONTENT (KJ/CM2) : 16.8 2.7 to 106.7 0.14 0.6
%area of TPW <45 mm upshear : 0.0 56.6 to 0.0 1.00 1.6
2nd PC OF IR BR TEMP : -0.9 2.2 to -2.3 0.68 0.6

SHIPS Prob RI for 20kt/ 12hr RI threshold= 12% is 1.9 times climatological mean ( 6.3%)
SHIPS Prob RI for 25kt/ 24hr RI threshold= 28% is 2.3 times climatological mean (12.5%)
SHIPS Prob RI for 30kt/ 24hr RI threshold= 20% is 2.4 times climatological mean ( 8.6%)
SHIPS Prob RI for 35kt/ 24hr RI threshold= 19% is 3.1 times climatological mean ( 6.2%)
SHIPS Prob RI for 40kt/ 24hr RI threshold= 11% is 2.7 times climatological mean ( 4.2%)
SHIPS Prob RI for 45kt/ 36hr RI threshold= 20% is 2.9 times climatological mean ( 6.7%)
SHIPS Prob RI for 55kt/ 48hr RI threshold= 17% is 2.9 times climatological mean ( 5.9%)
SHIPS Prob RI for 65kt/ 72hr RI threshold= 19% is 4.0 times climatological mean ( 4.7%)

Matrix of RI probabilities
------------------------------------------------------------------------------
RI (kt / h) | 20/12 | 25/24 | 30/24 | 35/24 | 40/24 | 45/36 | 55/48 |65/72
------------------------------------------------------------------------------
SHIPS-RII: 12.1% 28.2% 20.4% 19.1% 11.2% 19.5% 17.0% 18.9%
Logistic: 10.3% 31.8% 13.7% 8.9% 5.5% 22.5% 29.7% 5.7%
Bayesian: 5.0% 16.5% 7.7% 1.8% 0.7% 3.7% 0.3% 0.2%
Consensus: 9.1% 25.5% 14.0% 10.0% 5.8% 15.2% 15.7% 8.3%
DTOPS: 7.0% 29.0% 16.0% 14.0% 6.0% 15.0% 15.0% 9.0%

## ANNULAR HURRICANE INDEX (AHI) EP112021 ELEVEN 08/07/21 18 UTC ##
## STORM NOT ANNULAR, SCREENING STEP FAILED, NPASS=4 NFAIL=3 ##
## AHI= 0 (AHI OF 100 IS BEST FIT TO ANN. STRUC., 1 IS MARGINAL, 0 IS NOT ANNULAR) ##

[ElectricStorm]

Should see a hurricane out of this but I think a major is unlikely for now. The next system behind it might have a better shot to become something strong though.

[Yellow Evan]

SHIPS relies on the GFS for tracks. The GFS with it’s weird and overly broad spinup is likely overinflating wind shear over its official track that SHIPS is using. True wind shear looks to be around 8 knots by day 3, for example.

[Yellow Evan]

This feels like when when you are watching a football game and there’s a catch called live and on replay, it’s obvious his foot was out of bounds.

[Sciencerocks]

[Sciencerocks]

000
WTPZ41 KNHC 072038
TCDEP1

Tropical Storm Kevin Discussion Number 2
NWS National Hurricane Center Miami FL EP112021
300 PM MDT Sat Aug 07 2021

Visible satellite imagery has continued to show an improvement in
the cloud pattern of the tropical cyclone today. Banding has
increased over the western and southern portions of the circulation
while a small CDO has developed near the center. Scatterometer data
from around 1700 UTC revealed an area of 30-kt winds to the
northwest of the center, but with the continued increase in
organization and Dvorak T-numbers of T2.5 from both TAFB and SAB the
initial wind speed has been increased to 35 kt. Kevin becomes the
eleventh named storm in the eastern Pacific basin during the 2021
season, which is running about a month ahead of schedule as the
eleventh named storm typically does not form until early-to-mid
September.

Kevin is located within an environment of low-to-moderate shear,
warm sea surface temperatures, and a moist atmosphere. These
conditions are expected to support steady strengthening over the
next few days, and the cyclone is expected to become a hurricane
in about 36 hours. There is some spread in the intensity guidance
with the statistical guidance on the more aggressive side as
compared to some of the dynamical models. The NHC wind speed
forecast lies a little above the various consensus models but
slightly below the SHIPS guidance.

The storm is moving westward or 270/9 kt. A mid-tropospheric ridge
that extends across the subtropical eastern Pacific is forecast to
steer Kevin generally westward during the next 36 hours. After that
time, a cut-off low west of the Baja peninsula is expected to erode
the western portion of the ridge causing Kevin to turn west-
northwestward to northwestward through the remainder of the forecast
period. The GFS, which depicts an unrealistic elongation of the
system's low-level vorticity in about 48 hours, shows a much
sharper northward or northwestward motion from 48-72 hours. Less
weight was placed on that solution with the NHC track remaining
closer to the bulk of the guidance and the various consensus aids.
The latest track forecast is similar to, but a little slower than
previous advisory.


FORECAST POSITIONS AND MAX WINDS

INIT 07/2100Z 15.8N 106.8W 35 KT 40 MPH
12H 08/0600Z 15.8N 108.1W 45 KT 50 MPH
24H 08/1800Z 15.7N 109.4W 55 KT 65 MPH
36H 09/0600Z 15.7N 110.5W 65 KT 75 MPH
48H 09/1800Z 16.2N 111.5W 70 KT 80 MPH
60H 10/0600Z 17.3N 112.7W 75 KT 85 MPH
72H 10/1800Z 18.2N 114.0W 75 KT 85 MPH
96H 11/1800Z 19.9N 117.6W 65 KT 75 MPH
120H 12/1800Z 21.9N 122.2W 50 KT 60 MPH

$$
Forecaster Brown

[aspen]

“YET ANOTHER TROPICAL STORM FORMS OVER THE EAST PACIFIC”

The NHC is just as sick of these EPac storms as the rest of us lol

[cycloneye]

Tropical Storm Kevin Discussion Number 2
NWS National Hurricane Center Miami FL EP112021
300 PM MDT Sat Aug 07 2021

Visible satellite imagery has continued to show an improvement in
the cloud pattern of the tropical cyclone today. Banding has
increased over the western and southern portions of the circulation
while a small CDO has developed near the center. Scatterometer data
from around 1700 UTC revealed an area of 30-kt winds to the
northwest of the center, but with the continued increase in
organization and Dvorak T-numbers of T2.5 from both TAFB and SAB the
initial wind speed has been increased to 35 kt. Kevin becomes the
eleventh named storm in the eastern Pacific basin during the 2021
season, which is running about a month ahead of schedule as the
eleventh named storm typically does not form until early-to-mid
September.

Kevin is located within an environment of low-to-moderate shear,
warm sea surface temperatures, and a moist atmosphere. These
conditions are expected to support steady strengthening over the
next few days, and the cyclone is expected to become a hurricane
in about 36 hours. There is some spread in the intensity guidance
with the statistical guidance on the more aggressive side as
compared to some of the dynamical models. The NHC wind speed
forecast lies a little above the various consensus models but
slightly below the SHIPS guidance.

The storm is moving westward or 270/9 kt. A mid-tropospheric ridge
that extends across the subtropical eastern Pacific is forecast to
steer Kevin generally westward during the next 36 hours. After that
time, a cut-off low west of the Baja peninsula is expected to erode
the western portion of the ridge causing Kevin to turn west-
northwestward to northwestward through the remainder of the forecast
period. The GFS, which depicts an unrealistic elongation of the
system's low-level vorticity in about 48 hours, shows a much
sharper northward or northwestward motion from 48-72 hours. Less
weight was placed on that solution with the NHC track remaining
closer to the bulk of the guidance and the various consensus aids.
The latest track forecast is similar to, but a little slower than
previous advisory.


FORECAST POSITIONS AND MAX WINDS

INIT 07/2100Z 15.8N 106.8W 35 KT 40 MPH
12H 08/0600Z 15.8N 108.1W 45 KT 50 MPH
24H 08/1800Z 15.7N 109.4W 55 KT 65 MPH
36H 09/0600Z 15.7N 110.5W 65 KT 75 MPH
48H 09/1800Z 16.2N 111.5W 70 KT 80 MPH
60H 10/0600Z 17.3N 112.7W 75 KT 85 MPH
72H 10/1800Z 18.2N 114.0W 75 KT 85 MPH
96H 11/1800Z 19.9N 117.6W 65 KT 75 MPH
120H 12/1800Z 21.9N 122.2W 50 KT 60 MPH

$$
Forecaster Brown

[Yellow Evan]

“ Kevin becomes the
eleventh named storm in the eastern Pacific basin during the 2021
season, which is running about a month ahead of schedule as the
eleventh named storm typically does not form until early-to-mid
September.”

This is why named storms shouldn’t be used as the lone metric to evaluate activity.

[Stormybajan]

“ Kevin becomes the
eleventh named storm in the eastern Pacific basin during the 2021
season, which is running about a month ahead of schedule as the
eleventh named storm typically does not form until early-to-mid
September.”

This is why named storms should be used as the lone metric to evaluate activity.

Should or shouldnt? I like the amount of Hurricanes personally to gauge a season + ACE

[Yellow Evan]

“ Kevin becomes the
eleventh named storm in the eastern Pacific basin during the 2021
season, which is running about a month ahead of schedule as the
eleventh named storm typically does not form until early-to-mid
September.”

This is why named storms should be used as the lone metric to evaluate activity.

Should or shouldnt? I like the amount of Hurricanes personally to gauge a season + ACE

Shouldn’t.