CPAC: OLIVIA - Post-Tropical

[Yellow Evan]

01/2345 UTC 15.1N 111.5W T2.5/2.5 17E -- East Pacific

[Yellow Evan]

EP, 17, 2018090200, , BEST, 0, 151N, 1115W, 35, 1004, TS

[Yellow Evan]

* EAST PACIFIC 2018 SHIPS INTENSITY FORECAST *
* IR SAT DATA AVAILABLE, OHC AVAILABLE *
* SEVENTEEN EP172018 09/02/18 00 UTC *

TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120
V (KT) NO LAND 35 38 41 44 48 58 66 74 76 76 73 68 63
V (KT) LAND 35 38 41 44 48 58 66 74 76 76 73 68 63
V (KT) LGEM 35 37 39 41 43 47 53 58 59 56 52 47 43
Storm Type TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP

SHEAR (KT) 13 17 17 14 10 17 23 24 22 21 17 18 11
SHEAR ADJ (KT) 0 0 1 2 3 4 0 2 6 5 10 5 2
SHEAR DIR 15 13 25 41 57 72 75 67 67 58 57 48 64
SST (C) 29.8 29.8 29.8 29.8 29.7 29.6 29.4 29.2 28.9 28.6 28.3 27.8 26.8
POT. INT. (KT) 162 161 161 161 160 160 158 156 154 151 148 143 133
200 MB T (C) -52.5 -52.9 -53.1 -52.9 -52.4 -53.1 -52.3 -52.4 -51.8 -52.1 -51.7 -52.6 -52.4
200 MB VXT (C) -0.1 0.1 0.2 0.2 0.2 0.4 0.4 0.6 0.6 0.7 0.7 0.7 0.5
TH_E DEV (C) 7 7 7 7 7 7 7 6 6 5 4 4 4
700-500 MB RH 80 78 76 76 75 73 69 65 61 59 56 54 48
MODEL VTX (KT) 13 13 13 13 14 17 19 23 24 24 24 21 20
850 MB ENV VOR -35 -38 -49 -45 -39 -16 17 36 52 68 78 75 71
200 MB DIV 80 80 63 65 72 55 52 37 27 15 29 -9 11
700-850 TADV -4 -6 -4 -2 0 0 2 0 0 -5 -4 -11 -3
LAND (KM) 839 862 849 851 856 898 979 1098 1203 1328 1463 1597 1744
LAT (DEG N) 15.1 15.4 15.6 15.8 15.9 16.2 16.3 16.3 16.4 16.7 17.3 17.9 18.8
LONG(DEG W) 111.5 112.0 112.4 112.9 113.4 114.8 116.2 117.8 119.6 121.7 123.9 126.3 129.0
STM SPEED (KT) 7 5 5 5 6 7 7 8 10 10 11 13 13
HEAT CONTENT 27 27 27 27 26 16 11 14 11 12 7 3 2

FORECAST TRACK FROM OFCI INITIAL HEADING/SPEED (DEG/KT):285/ 9 CX,CY: -8/ 2
T-12 MAX WIND: 30 PRESSURE OF STEERING LEVEL (MB): 491 (MEAN=584)
GOES IR BRIGHTNESS TEMP. STD DEV. 50-200 KM RAD: 12.6 (MEAN=14.5)
% GOES IR PIXELS WITH T < -20 C 50-200 KM RAD: 84.0 (MEAN=65.0)
PRELIM RI PROB (DV .GE. 55 KT IN 48 HR): 15.8

INDIVIDUAL CONTRIBUTIONS TO INTENSITY CHANGE
6 12 18 24 36 48 60 72 84 96 108 120
----------------------------------------------------------
SAMPLE MEAN CHANGE 0. 0. 1. 1. 1. 1. 1. 0. -1. -1. -2. -3.
SST POTENTIAL 0. -1. -1. 0. 3. 8. 14. 20. 24. 27. 29. 28.
VERTICAL SHEAR MAG 0. 1. 1. 1. 2. 0. -3. -7. -11. -13. -14. -13.
VERTICAL SHEAR ADJ 0. 0. 0. 0. 0. 0. 0. 0. 1. 1. 1. 2.
VERTICAL SHEAR DIR 0. 0. 1. 1. 3. 5. 6. 7. 7. 8. 7. 7.
PERSISTENCE 1. 2. 2. 2. 1. 1. 1. 1. 1. 1. 1. 1.
200/250 MB TEMP. 0. 0. 0. 0. -1. -2. -2. -3. -3. -2. -1. -1.
THETA_E EXCESS 0. 0. 0. 0. 1. 1. 1. 0. 0. 0. -1. -2.
700-500 MB RH 0. 0. 1. 1. 1. 2. 2. 2. 2. 2. 1. 1.
MODEL VTX TENDENCY 0. 0. 0. 1. 4. 6. 12. 14. 16. 15. 12. 10.
850 MB ENV VORTICITY 0. 0. 0. 0. 1. 1. 1. 1. 1. 1. 1. 0.
200 MB DIVERGENCE 0. 1. 1. 1. 1. 1. 1. 1. 1. 1. 1. 0.
850-700 T ADVEC 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -1. -1.
ZONAL STORM MOTION 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
STEERING LEVEL PRES 0. 0. 0. 0. -1. -1. -1. -1. -1. -2. -2. -2.
DAYS FROM CLIM. PEAK 0. 0. 0. 0. 0. 0. 1. 1. 2. 2. 2. 2.
GOES PREDICTORS 1. 2. 2. 3. 3. 2. 1. 1. 1. 0. 0. 0.
OCEAN HEAT CONTENT 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
RI POTENTIAL 0. 1. 1. 2. 4. 5. 4. 2. 0. -1. -1. -2.
----------------------------------------------------------
TOTAL CHANGE 3. 6. 9. 13. 23. 31. 39. 41. 41. 38. 33. 28.

CURRENT MAX WIND (KT): 35. LAT, LON: 15.1 111.5

** 2018 E. Pacific RI INDEX EP172018 SEVENTEEN 09/02/18 00 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) : 125.9 40.5 to 149.3 0.78 7.0
12 HR PERSISTENCE (KT) : 5.0 -22.0 to 44.0 0.41 4.3
850-200 MB SHEAR (KT) : 14.1 19.6 to 1.4 0.30 2.5
HEAT CONTENT (KJ/CM2) : 26.8 1.8 to 106.7 0.24 1.6
D200 (10**7s-1) : 72.0 -33.0 to 156.2 0.55 4.1
STD DEV OF IR BR TEMP : 12.6 37.8 to 2.1 0.71 4.3
MAXIMUM WIND (KT) : 35.0 22.5 to 132.0 0.36 2.1
BL DRY-AIR FLUX (W/M2) : 54.0 721.6 to -82.5 0.83 -4.2
%area of TPW <45 mm upshear : 0.0 62.3 to 0.0 1.00 0.6
2nd PC OF IR BR TEMP : -1.2 2.2 to -1.9 0.84 0.8

SHIPS Prob RI for 20kt/ 12hr RI threshold= 13% is 2.1 times climatological mean ( 6.1%)
SHIPS Prob RI for 25kt/ 24hr RI threshold= 27% is 2.2 times climatological mean (12.5%)
SHIPS Prob RI for 30kt/ 24hr RI threshold= 23% is 2.7 times climatological mean ( 8.4%)
SHIPS Prob RI for 35kt/ 24hr RI threshold= 16% is 2.6 times climatological mean ( 6.0%)
SHIPS Prob RI for 40kt/ 24hr RI threshold= 11% is 2.6 times climatological mean ( 4.0%)
SHIPS Prob RI for 45kt/ 36hr RI threshold= 19% is 2.9 times climatological mean ( 6.5%)
SHIPS Prob RI for 55kt/ 48hr RI threshold= 20% is 3.4 times climatological mean ( 5.9%)
SHIPS Prob RI for 65kt/ 72hr RI threshold= 11% is 2.3 times climatological mean ( 4.8%)

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: 12.6% 27.0% 22.9% 15.6% 10.6% 19.1% 19.9% 11.2%
Logistic: 3.5% 23.9% 9.9% 5.9% 2.1% 10.0% 7.2% 4.6%
Bayesian: 0.3% 13.5% 3.3% 0.7% 0.3% 2.8% 1.9% 0.0%
Consensus: 5.5% 21.5% 12.0% 7.4% 4.3% 10.6% 9.6% 5.3%
DTOPS: 6.0% 17.0% 10.0% 6.0% 2.0% 20.0% 27.0% 37.0%

## ANNULAR HURRICANE INDEX (AHI) EP172018 SEVENTEEN 09/02/18 00 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) ##

CONTRIBUTIONS TO ANNULAR INDEX

[cycloneye]

Tropical Depression Seventeen-E Discussion Number 5
NWS National Hurricane Center Miami FL EP172018
900 PM MDT Sat Sep 01 2018

Satellite data indicate that the cyclone remains elongated from
northeast to southwest with the low-level center estimated to be on
the northeastern side of the main area of deep convection. Even
though the latest satellite intensity estimates suggest that the
system could be a tropical storm, the initial wind speed is held at
30 kt since the structure of the depression is not well organized.
This wind speed estimate is in agreement with an earlier ASCAT pass.

The depression is moving west-northwestward at 9 kt. The models
insist that the cyclone will slow down during the next day or two
while it lies to the south of a weakness in the subtropical ridge.
After that time, the subtropical ridge is expected to build to the
north of the depression, and that should cause it to move faster and
turn toward the west. Only small changes were made to the previous
forecast track and it remains on the southern side of the guidance
envelope in the short term, as many of the models show the
depression turning abruptly northward possibly due to the
reformation of the center. For now, the NHC track forecast assumes
that the center will not reform, but northward adjustments could be
required if that does occur.

The northeasterly shear that is currently affecting the depression
is expected to let up some during the next couple of days, which
should allow the system to at least gradually strengthen. However,
the intensity models are less aggressive this cycle, leaving the
previous forecast at the upper bound of the guidance envelope at
the longer forecast times. The new NHC intensity forecast is
largely an update of the previous one, except a little lower at the
longer range to trend toward the latest guidance. The confidence in
the intensity forecast is low because of the run-to-run variability
in the model guidance.

FORECAST POSITIONS AND MAX WINDS

INIT 02/0300Z 15.2N 111.8W 30 KT 35 MPH
12H 02/1200Z 15.7N 112.5W 35 KT 40 MPH
24H 03/0000Z 16.2N 113.6W 45 KT 50 MPH
36H 03/1200Z 16.6N 115.0W 55 KT 65 MPH
48H 04/0000Z 16.7N 116.4W 65 KT 75 MPH
72H 05/0000Z 16.8N 119.7W 80 KT 90 MPH
96H 06/0000Z 17.5N 124.2W 85 KT 100 MPH
120H 07/0000Z 19.0N 129.5W 85 KT 100 MPH

$$
Forecaster Cangialosi

[Yellow Evan]

* EAST PACIFIC 2018 SHIPS INTENSITY FORECAST *
* IR SAT DATA AVAILABLE, OHC AVAILABLE *
* OLIVIA EP172018 09/02/18 06 UTC *

TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120
V (KT) NO LAND 40 43 46 49 52 62 68 75 78 78 77 74 67
V (KT) LAND 40 43 46 49 52 62 68 75 78 78 77 74 67
V (KT) LGEM 40 44 47 50 53 60 65 67 64 61 58 53 47
Storm Type TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP

SHEAR (KT) 15 18 15 7 10 20 20 21 19 19 14 14 8
SHEAR ADJ (KT) 0 0 0 3 7 5 7 5 6 12 7 2 -1
SHEAR DIR 5 19 38 56 68 67 56 55 45 51 44 33 55
SST (C) 29.8 29.8 29.8 29.8 29.8 29.6 29.4 29.2 28.8 28.4 27.9 26.9 26.0
POT. INT. (KT) 162 161 161 161 162 160 158 156 153 149 144 134 125
200 MB T (C) -52.9 -53.1 -52.8 -52.2 -52.6 -52.4 -51.9 -52.1 -51.9 -52.0 -52.2 -52.4 -52.3
200 MB VXT (C) 0.1 0.2 0.2 0.3 0.4 0.4 0.8 0.8 0.8 0.7 0.6 0.5 0.6
TH_E DEV (C) 7 7 8 8 8 7 7 6 6 5 5 4 4
700-500 MB RH 76 73 72 72 70 67 62 59 55 58 55 53 50
MODEL VTX (KT) 14 14 15 15 16 22 23 27 27 27 27 27 24
850 MB ENV VOR -35 -50 -49 -37 -26 8 26 43 47 73 67 57 52
200 MB DIV 67 48 48 43 31 52 12 28 5 38 29 6 19
700-850 TADV -3 -2 -3 -2 -1 0 0 -3 -8 -11 -12 -17 -4
LAND (KM) 814 802 794 795 802 870 982 1077 1198 1359 1499 1654 1836
LAT (DEG N) 15.8 16.1 16.3 16.6 16.8 17.1 17.0 17.1 17.3 17.6 18.2 18.9 19.8
LONG(DEG W) 111.9 112.4 112.9 113.5 114.1 115.6 117.0 118.6 120.6 122.9 125.3 128.0 130.8
STM SPEED (KT) 7 5 6 6 7 7 7 9 10 12 13 13 14
HEAT CONTENT 26 26 27 24 20 12 11 13 19 7 5 0 0

FORECAST TRACK FROM OFCI INITIAL HEADING/SPEED (DEG/KT):295/ 8 CX,CY: -6/ 3
T-12 MAX WIND: 30 PRESSURE OF STEERING LEVEL (MB): 574 (MEAN=584)
GOES IR BRIGHTNESS TEMP. STD DEV. 50-200 KM RAD: 23.2 (MEAN=14.5)
% GOES IR PIXELS WITH T < -20 C 50-200 KM RAD: 66.0 (MEAN=65.0)
PRELIM RI PROB (DV .GE. 55 KT IN 48 HR): 14.3

INDIVIDUAL CONTRIBUTIONS TO INTENSITY CHANGE
6 12 18 24 36 48 60 72 84 96 108 120
----------------------------------------------------------
SAMPLE MEAN CHANGE 0. 0. 1. 1. 1. 1. 1. 0. -1. -1. -2. -3.
SST POTENTIAL 0. 0. 0. 1. 4. 8. 13. 18. 21. 23. 24. 23.
VERTICAL SHEAR MAG 0. 0. 1. 1. 1. 0. -3. -6. -9. -10. -10. -9.
VERTICAL SHEAR ADJ 0. 0. 0. 0. -1. -1. 0. 1. 1. 2. 2. 3.
VERTICAL SHEAR DIR 0. 0. 1. 1. 2. 4. 4. 5. 5. 5. 5. 4.
PERSISTENCE 2. 4. 4. 4. 4. 3. 2. 1. 2. 2. 1. 1.
200/250 MB TEMP. 0. 0. 0. 0. -1. -1. -1. -1. -1. -1. -1. 0.
THETA_E EXCESS 0. 0. 1. 1. 1. 2. 2. 1. 1. 1. 0. -1.
700-500 MB RH 0. 0. 0. 1. 1. 1. 1. 1. 1. 1. 0. 0.
MODEL VTX TENDENCY 0. 1. 1. 2. 7. 9. 14. 17. 17. 17. 17. 13.
850 MB ENV VORTICITY 0. 0. 0. 0. 1. 1. 1. 1. 1. 1. 0. 0.
200 MB DIVERGENCE 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. -1. -1.
850-700 T ADVEC 0. 0. 0. 0. 0. 0. 0. 0. 0. -1. -1. -2.
ZONAL STORM MOTION 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
STEERING LEVEL PRES 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
DAYS FROM CLIM. PEAK 0. 0. 0. 0. 0. 0. 1. 1. 2. 2. 2. 2.
GOES PREDICTORS 0. -1. -1. -2. -2. -2. -2. -2. -2. -1. -2. -2.
OCEAN HEAT CONTENT 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
RI POTENTIAL 0. 1. 1. 2. 3. 4. 3. 1. 0. -1. -1. -1.
----------------------------------------------------------
TOTAL CHANGE 3. 6. 9. 12. 22. 28. 35. 38. 38. 37. 34. 27.

CURRENT MAX WIND (KT): 40. LAT, LON: 15.8 111.9

** 2018 E. Pacific RI INDEX EP172018 OLIVIA 09/02/18 06 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) : 121.4 40.5 to 149.3 0.74 6.4
12 HR PERSISTENCE (KT) : 10.0 -22.0 to 44.0 0.48 4.9
850-200 MB SHEAR (KT) : 13.0 19.6 to 1.4 0.36 2.9
HEAT CONTENT (KJ/CM2) : 24.6 1.8 to 106.7 0.22 1.4
D200 (10**7s-1) : 47.4 -33.0 to 156.2 0.42 3.0
STD DEV OF IR BR TEMP : 23.2 37.8 to 2.1 0.41 2.4
MAXIMUM WIND (KT) : 40.0 22.5 to 132.0 0.51 2.9
BL DRY-AIR FLUX (W/M2) : 92.4 721.6 to -82.5 0.78 -3.9
%area of TPW <45 mm upshear : 0.0 62.3 to 0.0 1.00 0.6
2nd PC OF IR BR TEMP : -1.1 2.2 to -1.9 0.80 0.7

SHIPS Prob RI for 20kt/ 12hr RI threshold= 11% is 1.8 times climatological mean ( 6.1%)
SHIPS Prob RI for 25kt/ 24hr RI threshold= 22% is 1.8 times climatological mean (12.5%)
SHIPS Prob RI for 30kt/ 24hr RI threshold= 21% is 2.5 times climatological mean ( 8.4%)
SHIPS Prob RI for 35kt/ 24hr RI threshold= 15% is 2.5 times climatological mean ( 6.0%)
SHIPS Prob RI for 40kt/ 24hr RI threshold= 10% is 2.4 times climatological mean ( 4.0%)
SHIPS Prob RI for 45kt/ 36hr RI threshold= 17% is 2.6 times climatological mean ( 6.5%)
SHIPS Prob RI for 55kt/ 48hr RI threshold= 18% is 3.0 times climatological mean ( 5.9%)
SHIPS Prob RI for 65kt/ 72hr RI threshold= 11% is 2.2 times climatological mean ( 4.8%)

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: 10.9% 22.0% 21.4% 15.0% 9.5% 17.2% 18.0% 10.7%
Logistic: 1.9% 14.7% 6.1% 3.3% 0.9% 4.1% 2.8% 2.1%
Bayesian: 0.4% 6.4% 1.2% 0.2% 0.2% 0.5% 0.6% 0.0%
Consensus: 4.4% 14.4% 9.6% 6.2% 3.5% 7.3% 7.1% 4.3%
DTOPS: 11.0% 41.0% 30.0% 21.0% 10.0% 33.0% 41.0% 20.0%

## ANNULAR HURRICANE INDEX (AHI) EP172018 OLIVIA 09/02/18 06 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) ##

CONTRIBUTIONS TO ANNULAR INDEX

[Kingarabian]

We have Olivia.

[cycloneye]

Tropical Storm Olivia Discussion Number 6
NWS National Hurricane Center Miami FL EP172018
300 AM MDT Sun Sep 02 2018

The tropical cyclone's convection is still not well organized, and
the cloud pattern consists of an irregularly shaped CDO-like
feature with limited banding. Nonetheless, a couple of
scatterometer overpasses showed that the cyclone had winds to around
40 kt over the southern semicircle of the circulation. Therefore
the system is being named, and the aforementioned wind speed will be
used for the advisory intensity. The north-northeasterly shear
that has been affecting the storm is expected to abate somewhat,
which would allow for further strengthening. The official
intensity forecast is in line with the latest numerical model
consensus, IVCN. Some of the models show more rapid strengthening
during the next day or two, but this does not seem likely at this
time since the system is still not very well organized and some
shear is expected to continue affecting it.

The center was somewhat elongated in the scatterometer data, but
appeared to be located a little north of the previous working best
track. The initial motion is a rather uncertain 300/8 kt. A weak
mid-level ridge to the north of Olivia should lead to a slow
west-northwestward to northwestward motion over the next day or two.
Thereafter, a strengthening ridge is likely to cause a turn toward
the west with some increase in forward speed. Late in the forecast
period, the dynamical model consensus indicates a turn back to the
west-northwest. The official track forecast is a little north of
the previous one, mainly due to the recent re-positioning of the
center.

FORECAST POSITIONS AND MAX WINDS

INIT 02/0900Z 16.0N 112.2W 40 KT 45 MPH
12H 02/1800Z 16.6N 112.7W 45 KT 50 MPH
24H 03/0600Z 17.2N 113.6W 50 KT 60 MPH
36H 03/1800Z 17.5N 114.8W 60 KT 70 MPH
48H 04/0600Z 17.6N 116.6W 70 KT 80 MPH
72H 05/0600Z 17.7N 120.2W 85 KT 100 MPH
96H 06/0600Z 19.0N 124.5W 85 KT 100 MPH
120H 07/0600Z 20.5N 130.0W 75 KT 85 MPH

$$
Forecaster Pasch

[cycloneye]

Tropical Storm Olivia Discussion Number 7
NWS National Hurricane Center Miami FL EP172018
900 AM MDT Sun Sep 02 2018

Olivia is a sheared cyclone with the low-level center well removed
to the north of the convection. If it wasn't for the earlier
scatterometer, it would be difficult to assign an intensity of 40
kt at this time. In fact, Dvorak numbers do not support such wind
speeds. For continuity reasons, however, this is the assigned
intensity until new data become available.

Olivia is currently embedded in a hostile shear environment, but the
global models forecast a change to a more favorable upper-level wind
pattern soon. On this basis, the NHC forecast calls for Olivia to
begin strengthening tonight or early Monday, and reach hurricane
status in about 36 hours. This forecast is not different from the
previous one and follows the intensity consensus IVCN.

The circulation continues to be elongated, making it more difficult
to estimate the initial motion. The best estimate is toward the
northwest or 315 degrees at 6 kt. Most of the global models develop
a ridge to the north of the cyclone, and this flow pattern will
force Olivia to turn toward the west-northwest and west with some
increase in forward speed. Track guidance is clustered, and is
fairly consistent with the turn to the west. The NHC forecast
continues to be very close to the corrected consensus HCCA.

FORECAST POSITIONS AND MAX WINDS

INIT 02/1500Z 17.0N 112.4W 40 KT 45 MPH
12H 03/0000Z 17.7N 113.1W 40 KT 45 MPH
24H 03/1200Z 18.2N 114.3W 55 KT 65 MPH
36H 04/0000Z 18.2N 115.7W 65 KT 75 MPH
48H 04/1200Z 18.3N 117.2W 70 KT 80 MPH
72H 05/1200Z 19.0N 121.5W 85 KT 100 MPH
96H 06/1200Z 20.5N 126.5W 85 KT 100 MPH
120H 07/1200Z 22.0N 132.0W 75 KT 85 MPH

$$
Forecaster Avila

[cycloneye]

Tropical Storm Olivia Discussion Number 8
NWS National Hurricane Center Miami FL EP172018
300 PM MDT Sun Sep 02 2018

Olivia remains a sheared tropical cyclone with the low-level center
located to the north and northeast of the large area of deep
convection. Recent ASCAT data revealed a large area of 35-40 kt
winds over the southeastern portion of Olivia's circulation, and is
the basis for the initial wind speed of 40 kt. The global models
suggest that the northeasterly shear over the cyclone will not
abate as quickly as previous indicated, and much of the intensity
guidance shows less strengthening than before. The NHC wind speed
forecast has been lowered to be close to the intensity consensus,
but it is not as low as the statistical guidance in order to
maintain consistency with the previous official forecast. Olivia is
foreast to reach cooler waters around day 4 and the tropical
cyclone should weaken by that time.

The tropical storm is moving west-northwestward or 300/6 kt.
Olivia should turn westward as a large ridge builds to the north of
the system within the next couple of days. After midweek, Olivia
should turn back toward the west-northwest as it reaches the
western portion of the ridge. The dynamical model guidance
generally agrees with this overall scenario, but there is
cross-track spread regarding how much latitude the system
gains over the next couple of days. The NHC track is near the
various consensus aids and the GFS ensemble mean, but it is not as
far north as the latest run of the ECMWF that takes Olivia
more northwestward during the next 12 to 24 hours.

FORECAST POSITIONS AND MAX WINDS

INIT 02/2100Z 17.0N 113.4W 40 KT 45 MPH
12H 03/0600Z 17.4N 114.1W 40 KT 45 MPH
24H 03/1800Z 17.7N 115.3W 50 KT 60 MPH
36H 04/0600Z 17.9N 116.7W 60 KT 70 MPH
48H 04/1800Z 18.1N 118.6W 65 KT 75 MPH
72H 05/1800Z 19.0N 123.0W 75 KT 85 MPH
96H 06/1800Z 20.6N 128.4W 70 KT 80 MPH
120H 07/1800Z 22.3N 134.3W 60 KT 70 MPH

$$
Forecaster Brown

[Chris90]

Olivia would be doing a lot better if she could either wrap the deep convection around the LLC or pull the LLC under the deep convection. Might take her a little while before she gets her act together.

[cycloneye]

Olivia has underperformed.

[Sciencerocks]

Northerly shear has kept this in check.

Could continue for quite some time.

[cycloneye]

Tropical Storm Olivia Discussion Number 9
NWS National Hurricane Center Miami FL EP172018
900 PM MDT Sun Sep 02 2018

Olivia remains sheared, however the deep convection has inched a
little closer to the center this evening. The latest satellite
intensity estimates from TAFB and SAB are 35 and 45 kt,
respectively. Those estimates, along with the earlier ASCAT data,
support maintaining an initial intensity of 40 kt. The tropical
cyclone is expected to remain under the influence of moderate
northeasterly shear during the next several days, however, most of
the intensity guidance insists on some intensification while the
system moves over warm waters. The new NHC intensity forecast is
slightly higher than the previous advisory through 24 hours, but it
is similar to the earlier forecast by showing Olivia attaining
hurricane status in a couple of days. There is a large difference
between the latest statistical guidance and the dynamical hurricane
models, with the latter being much more aggressive in strengthening
Olivia. Given the current structure of the storm and the lower
statistical guidance, the NHC forecast splits the difference and is
close to the consensus guidance. Later in the period cooler waters
and a more stable airmass should cause the system to weaken.

Olivia is moving slowly west-northwestward or 295/4 kt. The track
forecast reasoning remains unchanged from the previous NHC
advisory. The tropical storm should turn westward as a ridge
builds to the north of the system within the next couple of days.
After midweek, Olivia should turn back toward the west-northwest as
it reaches the western portion of the ridge. There continues to be
some spread in the track guidance, and the NHC forecast is once
again near the model consensus to account for the differences.

FORECAST POSITIONS AND MAX WINDS

INIT 03/0300Z 17.1N 113.6W 40 KT 45 MPH
12H 03/1200Z 17.3N 114.4W 45 KT 50 MPH
24H 04/0000Z 17.6N 115.7W 55 KT 65 MPH
36H 04/1200Z 17.8N 117.4W 60 KT 70 MPH
48H 05/0000Z 18.0N 119.3W 65 KT 75 MPH
72H 06/0000Z 19.3N 123.9W 65 KT 75 MPH
96H 07/0000Z 20.8N 129.4W 60 KT 70 MPH
120H 08/0000Z 22.3N 135.0W 50 KT 60 MPH

$$
Forecaster Brown

[bob rulz]

Olivia has underperformed.

So far yes, but there's a lot of water ahead of her.

[hurricanes1234]

Olivia has underperformed.

So far yes, but there's a lot of water ahead of her.

And also a lot of shear.

[cycloneye]

Tropical Storm Olivia Discussion Number 11
NWS National Hurricane Center Miami FL EP172018
900 AM MDT Mon Sep 03 2018

There has been a pretty significant change with Olivia overnight,
with the center either moving into or reforming southward under the
central dense overcast. Microwave data indicate that a developing
inner core is present as well, along with a notable increase in
curved banding. Subjective Dvorak estimates have risen to 55 kt,
which agrees well with the latest CIMSS-SATCON estimates, so the
initial wind speed is raised to that value.

While the cyclone remains over warm water for the next couple of
days, northeasterly shear is forecast to persist, which should keep
the intensification rates of the cyclone in check, along with some
mid-level dry air. Slow strengthening seems most likely, and the
official forecast is raised from the previous one, mostly due to the
higher initial intensity. It should be noted that the corrected-
consensus guidance is even higher, so the intensity forecast could
be conservative. Olivia should move over more marginal waters in a
few days, and a gradual weakening is indicated at long range.

Olivia appears to be moving westward at about 6 kt, but this is
pretty uncertain due to the recent center jump. The storm should
move faster toward the west and eventually toward the west-
northwest during the next several days as it encounters a strong
ridge over the eastern Pacific Ocean. Almost all of the guidance is
south of the previous model cycle, which is consistent with a
stronger cyclone feeling the effects of a deep-layer ridge, so the
latest NHC forecast is shifted in that direction.

FORECAST POSITIONS AND MAX WINDS

INIT 03/1500Z 16.5N 114.5W 55 KT 65 MPH
12H 04/0000Z 16.5N 115.6W 60 KT 70 MPH
24H 04/1200Z 16.6N 117.4W 65 KT 75 MPH
36H 05/0000Z 16.9N 119.4W 70 KT 80 MPH
48H 05/1200Z 17.3N 121.7W 70 KT 80 MPH
72H 06/1200Z 18.6N 126.6W 60 KT 70 MPH
96H 07/1200Z 20.3N 132.2W 55 KT 65 MPH
120H 08/1200Z 22.0N 138.0W 50 KT 60 MPH

$$
Forecaster Blake

[cycloneye]

Hurricane Olivia Discussion Number 13
NWS National Hurricane Center Miami FL EP172018
800 PM PDT Mon Sep 03 2018

Olivia continues to strengthen with convection deepening near the
center, and the latest microwave passes show a nearly complete
eyewall underneath the central dense overcast. Dvorak estimates
from TAFB/SAB are a consensus 65 kt, and that will be the initial
wind speed.

A bit surprisingly, Olivia has intensified 25 kt over the past 24
hours. The current northeasterly shear apparently has not been
enough to cause the strengthening rate to decrease, although some
models are still suggesting the shear will disrupt the hurricane
over the next couple of days. After inspecting the environmental
winds, it appears that most of the shear will avoid the inner core,
so the official forecast is raised from the previous one, lying near
the upper edge of the guidance. This forecast still feels a bit
conservative, given the explosive nature of many of the 2018
eastern Pacific cyclones. Olivia should move over more marginal
waters in a few days, and a gradual weakening is indicated at long
range.

A gradual acceleration continues with Olivia, now moving westward
at about 8 kt. A strengthening ridge over the eastern Pacific
should steer the cyclone westward and west-northwestward at an
increasing forward pace over the next several days. The model
guidance is tightly packed on this solution, and the latest NHC
track forecast is basically just an update of the previous
prediction.

FORECAST POSITIONS AND MAX WINDS

INIT 04/0300Z 16.8N 116.0W 65 KT 75 MPH
12H 04/1200Z 16.9N 117.4W 75 KT 85 MPH
24H 05/0000Z 17.1N 119.5W 85 KT 100 MPH
36H 05/1200Z 17.4N 121.8W 85 KT 100 MPH
48H 06/0000Z 18.0N 124.2W 85 KT 100 MPH
72H 07/0000Z 19.7N 129.7W 75 KT 85 MPH
96H 08/0000Z 21.5N 135.3W 65 KT 75 MPH
120H 09/0000Z 23.0N 140.5W 55 KT 65 MPH

$$
Forecaster Blake

[bob rulz]

Olivia has underperformed.

So far yes, but there's a lot of water ahead of her.

And also a lot of shear.

Yeah but how often have the shear forecasts in the East Pacific busted this year?

[cycloneye]

Hurricane Olivia Discussion Number 14
NWS National Hurricane Center Miami FL EP172018
200 AM PDT Tue Sep 04 2018

A recent SSMIS overpass indicated a banding eye inner core
structure with improved deep convective outer bands over the
southern semicircle. A 0432 UTC ASCAT-B scatterometer pass was
used to adjust the wind radii for this advisory package. A blend
of the subjective satellite intensity estimates support a slight
initial intensity increase to 70 kt.

Olivia has about 24-36 hours or so remaining over warm SSTs with
marginally favorable upper wind conditions. Therefore strengthening
is forecast for the next day or so, similar to the HCCA and IVCN
consensus models. After that time, The cyclone is expected to
traverse slightly cooler oceanic surface temperatures, and gradual
weakening is indicated through day 5. The NHC forecast is based on
the above consensus models and is similar to the previous advisory.

The initial motion is estimated to be westward, or 275/10 kt. A
building subtropical ridge over the eastern Pacific is forecast
to induce a westward and west-northwestward motion with
increasing forward speed during the next several days. The model
guidance is tightly packed on this solution, and the latest NHC
track forecast is basically just an update of the previous
prediction.

FORECAST POSITIONS AND MAX WINDS

INIT 04/0900Z 16.9N 117.2W 70 KT 80 MPH
12H 04/1800Z 17.0N 118.8W 80 KT 90 MPH
24H 05/0600Z 17.2N 120.9W 85 KT 100 MPH
36H 05/1800Z 17.7N 123.3W 85 KT 100 MPH
48H 06/0600Z 18.4N 125.9W 80 KT 90 MPH
72H 07/0600Z 20.1N 131.4W 75 KT 85 MPH
96H 08/0600Z 21.9N 137.0W 60 KT 70 MPH
120H 09/0600Z 23.0N 142.0W 55 KT 65 MPH

$$
Forecaster Roberts

[Yellow Evan]

04/1200 UTC 16.9N 117.7W T5.0/5.0 OLIVIA -- East Pacific