CPAC: LINDA - Post-Tropical

[ElectricStorm]

It's nice to see an EPAC storm perform well after all those disappointments. Way to go Linda

[Yellow Evan]

----- Current Analysis -----
Date : 13 AUG 2021 Time : 175032 UTC
Lat : 17:10:12 N Lon : 112:08:23 W


CI# /Pressure/ Vmax
5.5 / 959.1mb/102.0kt


Final T# Adj T# Raw T#
5.5 5.6 5.6

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

Center Temp : +13.0C Cloud Region Temp : -57.2C

Scene Type : EYE

[Yellow Evan]

Warm eye persisting so despite the dry air this is probably a major.

[Yellow Evan]

Wrapping around colder cloud tops but dry air still lurking.

[Yellow Evan]

----- Current Analysis -----
Date : 13 AUG 2021 Time : 182032 UTC
Lat : 17:12:35 N Lon : 112:19:11 W


CI# /Pressure/ Vmax
5.5 / 959.0mb/102.0kt


Final T# Adj T# Raw T#
5.5 5.6 5.6

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

Center Temp : +12.0C Cloud Region Temp : -57.2C

Scene Type : EYE

[Kingarabian]

Is now a major hurricane

[InfernoFlameCat]

Impressive. I believe it will peak at 115 knots. shear will limit it.

[Yellow Evan]

* GFS version *
* EAST PACIFIC 2021 SHIPS INTENSITY FORECAST *
* IR SAT DATA AVAILABLE, OHC AVAILABLE *
* LINDA EP122021 08/13/21 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 100 104 106 107 105 97 90 86 82 79 79 73 68 64 58 52 47
V (KT) LAND 100 104 106 107 105 97 90 86 82 79 79 73 68 64 58 52 47
V (KT) LGEM 100 105 106 105 102 91 82 74 67 62 61 59 55 49 40 33 28
Storm Type TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP

SHEAR (KT) 10 7 5 4 6 10 9 6 5 0 1 3 2 3 2 7 3
SHEAR ADJ (KT) 0 0 4 2 1 2 0 0 -2 -4 3 0 3 5 6 6 5
SHEAR DIR 11 24 44 74 90 65 41 43 16 115 69 160 267 155 158 158 168
SST (C) 27.4 27.6 28.0 28.3 27.7 26.9 26.2 26.1 25.2 25.6 26.3 25.6 24.8 23.3 22.7 22.9 23.4
POT. INT. (KT) 139 141 145 148 142 133 125 124 115 119 126 119 111 96 89 92 97
200 MB T (C) -53.4 -53.0 -53.2 -53.2 -52.9 -53.0 -53.0 -53.0 -53.0 -52.7 -52.8 -52.3 -52.5 -52.3 -52.5 -52.5 -52.7
200 MB VXT (C) 0.3 0.5 0.6 0.4 0.4 0.5 0.4 0.6 0.7 0.7 0.7 0.5 0.8 0.7 0.8 0.4 0.2
TH_E DEV (C) 6 6 6 6 5 5 4 4 3 3 3 3 2 2 1 2 2
700-500 MB RH 75 74 70 71 68 62 59 55 55 51 51 48 46 42 38 36 30
MODEL VTX (KT) 22 23 23 25 25 25 25 27 27 26 27 25 23 20 17 14 10
850 MB ENV VOR -15 -15 -21 -22 -14 -1 7 15 31 49 65 69 55 49 34 31 31
200 MB DIV 48 29 12 10 29 3 -1 -10 6 1 -19 -20 -30 -9 -10 -1 -11
700-850 TADV -6 -1 0 1 1 6 3 1 4 1 1 0 0 5 0 3 3
LAND (KM) 677 685 717 776 818 960 1135 1317 1495 1657 1821 1952 2056 2090 1872 1643 1422
LAT (DEG N) 17.2 17.7 18.1 18.5 18.8 18.9 18.8 18.5 18.0 17.7 17.6 18.1 19.1 xx.x xx.x xx.x xx.x
LONG(DEG W) 112.3 113.5 114.6 115.7 116.9 119.1 121.2 123.1 125.0 126.9 128.9 130.9 132.8 xxx.x xxx.x xxx.x xxx.x
STM SPEED (KT) 12 12 11 11 11 10 10 9 9 9 10 10 10 11 11 12 12
HEAT CONTENT 7 7 9 10 7 3 0 0 0 0 1 0 0 0 0 0 0

FORECAST TRACK FROM OFCI INITIAL HEADING/SPEED (DEG/KT):300/ 12 CX,CY: -9/ 6
T-12 MAX WIND: 80 PRESSURE OF STEERING LEVEL (MB): 557 (MEAN=587)
GOES IR BRIGHTNESS TEMP. STD DEV. 50-200 KM RAD: 9.2 (MEAN=14.5)
% GOES IR PIXELS WITH T < -20 C 50-200 KM RAD: 98.0 (MEAN=65.0)
PRELIM RI PROB (DV .GE. 35 KT IN 36 HR): 3.6

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 -1. -1. -1. -2. -7. -14. -21. -28. -34. -38. -41. -43. -47. -51. -56. -61.
VERTICAL SHEAR MAG -1. -1. -1. -1. -1. 0. 3. 5. 7. 9. 10. 11. 11. 11. 12. 13.
VERTICAL SHEAR ADJ -0. -0. -0. -0. -1. -1. -0. -0. 0. 0. 0. 0. -0. -0. -0. -0.
VERTICAL SHEAR DIR 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -0. -1. -1. -1. -1. -1.
PERSISTENCE 5. 7. 7. 6. 4. 2. -1. -2. -2. -2. -3. -3. -3. -3. -3. -3.
200/250 MB TEMP. 0. 0. 0. 0. 0. 0. 1. 2. 3. 3. 3. 4. 4. 5. 5. 5.
THETA_E EXCESS -0. -0. -0. -0. -1. -1. -2. -3. -4. -4. -5. -5. -6. -7. -8. -10.
700-500 MB RH 0. 0. 0. 0. 1. 0. 0. 0. 0. -0. -0. -0. -1. -1. -2. -3.
MODEL VTX TENDENCY 0. 1. 2. 3. 2. 3. 6. 6. 5. 6. 3. 1. -2. -5. -8. -9.
850 MB ENV VORTICITY -0. -0. -0. -0. -0. 0. 0. 0. 1. 0. 0. 0. 0. 0. 0. 0.
200 MB DIVERGENCE -0. -0. -0. -0. -0. -1. -2. -3. -3. -4. -4. -3. -2. -1. 0. 1.
850-700 T ADVEC 0. 0. 0. 0. -0. 0. 0. 0. 0. 0. 0. 0. 0. 1. 1. 1.
ZONAL STORM MOTION 0. 0. 0. 1. 1. 1. 1. 1. 1. 1. 1. 1. 0. 0. 0. -0.
STEERING LEVEL PRES -0. -0. -0. -0. -0. -0. -0. -0. -0. -0. -0. -0. -0. -0. -0. -0.
DAYS FROM CLIM. PEAK 0. 0. 0. 0. 0. 0. 1. 1. 1. 2. 2. 2. 3. 3. 3. 4.
GOES PREDICTORS 0. 1. 0. 0. 1. 2. 2. 2. 3. 3. 3. 3. 4. 3. 3. 3.
OCEAN HEAT CONTENT -0. -0. -0. -0. -0. -1. -1. -1. -0. -0. 0. 1. 2. 2. 4. 6.
RI POTENTIAL -0. -1. -1. -2. -3. -3. -2. -1. 1. 2. 3. 4. 4. 4. 4. 3.
------------------------------------------------------------------------------
TOTAL CHANGE 5. 6. 7. 5. -3. -10. -14. -18. -21. -21. -27. -32. -36. -42. -48. -53.

CURRENT MAX WIND (KT): 100. LAT, LON: 17.2 112.3

** 2021 E. Pacific RI INDEX EP122021 LINDA 08/13/21 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) : 42.8 40.5 to 149.3 0.02 0.2
12 HR PERSISTENCE (KT) : 20.0 -22.0 to 44.0 0.64 5.5
D200 (10**7s-1) : 25.6 -33.0 to 159.5 0.30 2.1
850-200 MB SHEAR (KT) : 6.6 19.6 to 1.3 0.71 4.8
MAXIMUM WIND (KT) : 100.0 22.5 to 132.0 0.43 2.3
STD DEV OF IR BR TEMP : 9.2 37.8 to 2.1 0.80 3.8
BL DRY-AIR FLUX (W/M2) : 366.6 800.8 to -82.5 0.49 -2.6
HEAT CONTENT (KJ/CM2) : 8.0 2.7 to 106.7 0.05 0.2
%area of TPW <45 mm upshear : 0.0 56.6 to 0.0 1.00 1.5
2nd PC OF IR BR TEMP : 0.7 2.2 to -2.3 0.34 0.3

SHIPS Prob RI for 20kt/ 12hr RI threshold= 13% is 2.1 times climatological mean ( 6.3%)
SHIPS Prob RI for 25kt/ 24hr RI threshold= 19% is 1.5 times climatological mean (12.5%)
SHIPS Prob RI for 30kt/ 24hr RI threshold= 18% is 2.1 times climatological mean ( 8.6%)
SHIPS Prob RI for 35kt/ 24hr RI threshold= 17% is 2.7 times climatological mean ( 6.2%)
SHIPS Prob RI for 40kt/ 24hr RI threshold= 0% is 0.0 times climatological mean ( 4.2%)
SHIPS Prob RI for 45kt/ 36hr RI threshold= 0% is 0.0 times climatological mean ( 6.7%)
SHIPS Prob RI for 55kt/ 48hr RI threshold= 0% is 0.0 times climatological mean ( 5.9%)
SHIPS Prob RI for 65kt/ 72hr RI threshold= 0% is 0.0 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: 13.3% 18.7% 17.9% 17.0% 0.0% 0.0% 0.0% 0.0%
Logistic: 6.8% 5.0% 2.9% 2.2% 0.4% 1.1% 0.5% 0.1%
Bayesian: 1.3% 1.0% 0.1% 0.0% 0.0% 0.0% 0.0% 0.0%
Consensus: 7.1% 8.2% 7.0% 6.4% 0.1% 0.4% 0.2% 0.0%
DTOPS: 21.0% 9.0% 6.0% 5.0% 3.0% 0.0% 0.0% 0.0%

## ANNULAR HURRICANE INDEX (AHI) EP122021 LINDA 08/13/21 18 UTC ##
## PASSED SCREENING STEP, MIGHT BE ANNULAR, CALCULATE AHI FROM DISCRIMINANT ANALYSIS ##
## AHI= 1 (AHI OF 100 IS BEST FIT TO ANN. STRUC., 1 IS MARGINAL, 0 IS NOT ANNULAR) ##

[Yellow Evan]

I'm not sure how much stronger Linda will get. Dry air is lurking nearby as is and occasionally getting in despite the warm eye just because Linda is somewhat banding dominant. This sort of structure is also vulnerable to an ERC, which would let even more dry, stable air in, and could permanently damage its inner core.

[Sciencerocks]

[Kingarabian]

HWRF and Euro still have this going annular

[Yellow Evan]

Been a while since I've seen dry air be such a problem in an intensifying storm. Could really use some microwave rn to see if this is a mess or not.

[Kingarabian]

Seen systems do better with worse dry air around. Maybe its structure is allowing for more intrusion than usual.

[NDG]

Finally a system that gets a break from the shear over the EPAC

[Kingarabian]

Hurricane Linda Discussion Number 15
NWS National Hurricane Center Miami FL EP122021
300 PM MDT Fri Aug 13 2021

Linda has become an impressive looking hurricane this afternoon. The
eye that first became evident on geostationary satellite imagery
this morning has continued to clear out and warm while the
surrounding cold convection associated with the eyewall wraps around
the eye. The convective structure on microwave imagery has also
improved, with a distinct eye and closed eyewall apparent in an
earlier 1417 UTC SSMIS pass. The 1800 UTC subjective and objective
Dvorak estimates were in unanimous agreement with T5.5/102 kt
provided by SAB, TAFB, and ADT sources. Therefore, the initial
intensity has been increased to 100 kt this advisory, making Linda a
major hurricane.

Linda continues to move steadily to the west-northwest, at 300/12
kt. The track philosophy has not changed much over the past 24
hours. A mid- to upper-level ridge currently centered over the
southwestern United States is expected to expand westward, building
in to the northwest of the hurricane. This evolution should result
in Lisa's motion bending left, first to the west, and then to the
west-southwest over the next 2-3 days. The track guidance remains
tightly clustered near and just slightly poleward of the previous
forecast track. The latest NHC track forecast was nudged just
slightly northward over the first few days, but is nearly on top of
the previous forecast by the end of the period.

Linda has rapidly intensified, with a 35-kt increase over the past
24 hours, and the hurricane still has an opportunity to intensify a
bit more over the next 12 hours. After 24 hours, Linda will begin to
cross over gradually decreasing sea-surface temperatures and into a
and drier mid-level environment. These factors should lead to
gradual weakening. One fly in the ointment is that the shear
diagnosed by SHIPS guidance is expected to remain low and easterly
while sea-surface temperatures remain between 26-27 C through 60
hours. Both the ECMWF and HWRF simulated brightness temperatures
during that time suggest that Linda could develop a stable annular
structure, which often results in a slower than expected weakening
rate. For this reason, the latest intensity forecast only shows
gradual weakening through 60 hours, which is a bit above the HCCA
consensus aid. More rapid weakening is likely at the end of the
forecast period when Linda will move over sub 25 C water.


FORECAST POSITIONS AND MAX WINDS

INIT 13/2100Z 17.5N 112.9W 100 KT 115 MPH
12H 14/0600Z 18.2N 114.6W 110 KT 125 MPH
24H 14/1800Z 18.9N 116.9W 105 KT 120 MPH
36H 15/0600Z 19.2N 119.2W 100 KT 115 MPH
48H 15/1800Z 19.1N 121.3W 95 KT 110 MPH
60H 16/0600Z 18.7N 123.3W 85 KT 100 MPH
72H 16/1800Z 18.2N 125.2W 75 KT 85 MPH
96H 17/1800Z 17.9N 129.0W 65 KT 75 MPH
120H 18/1800Z 19.0N 133.0W 55 KT 65 MPH

$$
Forecaster Papin/Brennan

The possibility of this becoming annular and the possibility that this goes more south than advertised could keep this a respectable system and big ACE maker than forecast.

[Astromanía]

Its tropical storm wind field is big but not its hurricane wind field. It could make landfall on Clarion island or just pass to the south as a major

[Kingarabian]

Trying to wrap a B ring:

[Kingarabian]

AMSR2 Pass:



GMI Pass:



Quite dry at the mid level but as stable as it gets.

[Yellow Evan]

Inner core seems quite stable so my fears of an ERC are quelled. I think Kevin’s cold wake in addition dry air are contributing to the shallow convection on the north side.

[Kingarabian]

Also still hints of northerly shear keeping some sort of lid on intensity: