EPAC: NORA - Remnants

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Re: EPAC: EIGHTEEN-E - Tropical Depression

#21 Postby cycloneye » Fri Oct 09, 2015 9:55 am

TROPICAL DEPRESSION EIGHTEEN-E DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182015
800 AM PDT FRI OCT 09 2015

Satellite images indicate that the area of low pressure in the far
southwestern portion of the eastern Pacific has become better
organized. Curved banding features have increased, along with a
growing area of deep convection near the center. Thus the system
is declared a tropical depression, the 18th of the season. The
initial wind speed is set to 30 kt using the Dvorak estimate
from TAFB. The minimum pressure is 1008 mb on the basis of buoy
43535 near the depression, which reported 1009 mb a couple of hours
ago.

The cyclone is expected to be in a favorable environment for
strengthening for the next few days, with low wind shear, very warm
waters and high mid-level moisture. Thus steady intensification is
forecast until early next week. Thereafter, an increase in
southwesterly shear and some cooler waters should cause the cyclone
to weaken some by day 5. The official intensity prediction is on
the high side of the intensity guidance, a reflection of both the
conducive environment and the low bias of the guidance during this
season. It would not be surprising if the cyclone intensified more
than shown here given the large-scale environment, but timing this
is not possible at this time.

The depression is moving westward at about 12 kt. This general
motion is expected for the next 2-3 days while it remains under the
influence of the subtropical ridge located over the eastern and
central Pacific. This pattern is expected to change quickly after
day 3 when a mid-latitude trough erodes the ridge, causing the
cyclone to recurve well east of the Hawaiian Islands. For a first
forecast, the guidance is in rather good agreement, and the
official forecast is close to the overall consensus, with a bit more
weight on the ECMWF model.


FORECAST POSITIONS AND MAX WINDS

INIT 09/1500Z 11.1N 132.0W 30 KT 35 MPH
12H 10/0000Z 11.3N 133.8W 35 KT 40 MPH
24H 10/1200Z 11.7N 136.2W 45 KT 50 MPH
36H 11/0000Z 12.0N 138.8W 55 KT 65 MPH
48H 11/1200Z 12.2N 140.9W 65 KT 75 MPH
72H 12/1200Z 12.8N 143.5W 85 KT 100 MPH
96H 13/1200Z 14.5N 145.0W 85 KT 100 MPH
120H 14/1200Z 17.0N 144.0W 75 KT 85 MPH

$$
Forecaster Blake
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#22 Postby talkon » Fri Oct 09, 2015 11:23 am

This one might be the one to cross 140W from west to east, based on the models.
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#23 Postby Yellow Evan » Fri Oct 09, 2015 2:38 pm

Lots of uncertainties this morning. The ECMWF keeps this a tropical storm, and most of the guidance in general has come down. Still the GFS forecasts low shear and good outflow, and if those verify, there is little reason to not expect a major hurricane. Biggest cavet will be the timing of the development of an inner core due to the presence of dry air.
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#24 Postby cycloneye » Fri Oct 09, 2015 3:37 pm

TROPICAL DEPRESSION EIGHTEEN-E DISCUSSION NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182015
200 PM PDT FRI OCT 09 2015

The depression has not changed much since the previous advisory. The
associated deep convection is organized in a curved band to the
north and west of the center with a more linear swath of clouds a
couple of hundred n mi to the northeast of the center. The Dvorak
classifications from TAFB, SAB, and UW-CIMSS ADT remain 2.0/30 kt,
and a recent ASCAT pass also showed winds around that value. Based
on these data, the initial wind speed remains 30 kt.

The depression is moving westward at about 14 kt steered by a
subtropical ridge to its north. This general heading with a
decrease in forward speed is expected during the next 2-3 days while
the ridge weakens. After that time, a turn toward the north and
then northeast is predicted when the system becomes embedded in the
flow ahead of a large trough. The official track forecast is a
little to the south of the previous one in the short term, mainly
due to the more southward initial motion, and then slightly to the
east of the previous track to come into better agreement with the
latest models.

Environmental conditions are expected to be conducive for
strengthening during the next few days, and accordingly most of the
guidance shows the cyclone intensifying. The SHIPS model shows the
shear increasing in 4 to 5 days, and that, along with more stable
air and decreasing SSTs, should end the strengthening trend and
induce weakening. The official intensity forecast is unchanged from
the previous one, and remains near the high end of the guidance.

FORECAST POSITIONS AND MAX WINDS

INIT 09/2100Z 10.9N 133.5W 30 KT 35 MPH
12H 10/0600Z 11.1N 135.3W 35 KT 40 MPH
24H 10/1800Z 11.4N 137.8W 45 KT 50 MPH
36H 11/0600Z 11.6N 140.1W 55 KT 65 MPH
48H 11/1800Z 11.8N 141.9W 65 KT 75 MPH
72H 12/1800Z 12.5N 144.2W 85 KT 100 MPH
96H 13/1800Z 14.3N 144.8W 80 KT 90 MPH
120H 14/1800Z 17.3N 143.2W 70 KT 80 MPH

$$
Forecaster Cangialosi
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Re: EPAC: EIGHTEEN-E - Tropical Depression

#25 Postby Yellow Evan » Fri Oct 09, 2015 9:03 pm

Code: Select all

v                    * EAST PACIFIC SHIPS INTENSITY FORECAST          *
                    * IR SAT DATA AVAILABLE,       OHC AVAILABLE     *
                    *  EIGHTEEN    EP182015  10/10/15  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    57    64    71    74    70    69    66    64
V (KT) LAND       35    38    41    44    48    57    64    71    74    70    69    66    64
V (KT) LGE mod    35    38    41    44    48    56    64    71    76    76    73    68    63
Storm Type      TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP

SHEAR (KT)         7     8     7     4     2     4     3     6     3    14    16    19    21
SHEAR ADJ (KT)    -2    -4    -6    -8    -4     0    -1    -2     2     5     3     2     5
SHEAR DIR        121   136   152   187   191   181   150   175   251   276   251   222   203
SST (C)         29.8  29.7  29.6  29.5  29.4  29.1  29.0  28.9  28.8  28.7  28.4  27.8  27.3
POT. INT. (KT)   165   163   162   161   159   155   153   151   150   150   148   142   137
200 MB T (C)   -52.3 -52.5 -52.7 -52.4 -51.8 -51.9 -51.6 -51.6 -51.2 -51.7 -51.5 -52.2 -51.7
TH_E DEV (C)       9    10    10     9    10     8     8     8     9     9     9     8     8
700-500 MB RH     68    65    61    59    56    57    55    54    53    51    51    55    54
MODEL VTX (KT)    11    12    12    12    13    16    17    19    21    20    21    21    22
850 MB ENV VOR   -14   -11    -8     7    18    39    58    63    56    55    44    36    21
200 MB DIV        22    11    16    19    19    43    68    57    61    38    57    81   109
700-850 TADV       5     3     3     2     2     0     0     0     0    -1     3     7     6
LAND (KM)       2362  2232  2103  1979  1856  1654  1499  1367  1279  1196  1129  1148  1258
LAT (DEG N)     11.2  11.4  11.5  11.7  11.8  11.9  12.2  12.6  13.0  13.9  15.3  16.8  18.3
LONG(DEG W)    134.5 135.8 137.0 138.2 139.4 141.5 143.0 144.2 144.9 145.2 145.1 144.3 142.9
STM SPEED (KT)    14    12    12    12    11     9     7     5     4     6     8     9    10
HEAT CONTENT      41    30    20    17    19    19    20    29    26    18    15    10    21

  FORECAST TRACK FROM OFCI      INITIAL HEADING/SPEED (DEG/KT):280/ 15      CX,CY: -14/  3
  T-12 MAX WIND:  30            PRESSURE OF STEERING LEVEL (MB):  472  (MEAN=581)
  GOES IR BRIGHTNESS TEMP. STD DEV.  50-200 KM RAD:  18.7 (MEAN=14.5)
  % GOES IR PIXELS WITH T < -20 C    50-200 KM RAD:  68.0 (MEAN=65.0)

                        INDIVIDUAL CONTRIBUTIONS TO INTENSITY CHANGE
                         6   12   18   24   36   48   60   72   84   96  108  120
                        ----------------------------------------------------------
  SAMPLE MEAN CHANGE     0.   0.   0.   1.   1.   1.   0.   0.  -1.  -1.  -2.  -2.
  SST POTENTIAL          0.   1.   2.   3.   8.  14.  20.  24.  26.  27.  28.  29.
  VERTICAL SHEAR MAG     1.   1.   2.   4.   6.   8.   9.  11.  10.   9.   8.   6.
  VERTICAL SHEAR ADJ     0.   1.   1.   2.   2.   2.   2.   1.   1.   1.   0.   0.
  VERTICAL SHEAR DIR     0.   0.   0.  -1.  -1.  -2.  -3.  -5.  -8. -10. -10. -10.
  PERSISTENCE            1.   1.   2.   2.   2.   2.   1.   1.   1.   1.   1.   0.
  200/250 MB TEMP.       0.  -1.  -2.  -3.  -5.  -7.  -9. -10. -11. -11. -11. -11.
  THETA_E EXCESS         0.   0.   0.   1.   1.   1.   1.   1.   1.   1.   1.   0.
  700-500 MB RH          0.   0.   0.   0.   0.   1.   1.   1.   0.   0.   0.   1.
  MODEL VTX TENDENCY     0.   1.   1.   2.   6.   8.  12.  14.  14.  16.  15.  16.
  850 MB ENV VORTICITY   0.   0.   0.   0.   0.   0.   0.   1.   1.   1.   2.   2.
  200 MB DIVERGENCE      0.   0.   0.   0.   0.   0.   1.   1.   0.   0.  -1.  -1.
  850-700 T ADVEC        0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   0.   1.
  ZONAL STORM MOTION     0.   1.   1.   2.   3.   4.   5.   5.   4.   4.   4.   4.
  STEERING LEVEL PRES    0.   0.   0.   0.  -1.  -1.  -1.  -2.  -2.  -2.  -2.  -2.
  DAYS FROM CLIM. PEAK   0.   0.   0.   0.   0.   0.   0.   0.  -1.  -1.  -1.  -1.
  GOES PREDICTORS        0.   0.   0.   0.   0.  -1.  -2.  -2.  -2.  -2.  -2.  -2.
  OCEAN HEAT CONTENT     0.   0.   0.   1.   1.   1.   1.   1.   1.   1.   0.   0.
                        ----------------------------------------------------------
  TOTAL CHANGE           3.   6.   9.  13.  22.  29.  36.  39.  35.  34.  31.  29.

   ** 2013 E. Pacific RI INDEX EP182015 EIGHTEEN   10/10/15  00 UTC **
           ( 30 KT OR MORE MAX WIND INCREASE IN NEXT 24 HR)
 
 12 HR PERSISTENCE (KT):   5.0 Range:-22.0 to  38.5 Scaled/Wgted Val:  0.4/  1.0
 850-200 MB SHEAR (KT) :   5.5 Range: 18.7 to   1.4 Scaled/Wgted Val:  0.8/  1.1
 POT = MPI-VMAX (KT)   : 126.8 Range: 40.3 to 141.7 Scaled/Wgted Val:  0.9/  0.9
 STD DEV OF IR BR TEMP :  18.7 Range: 38.9 to   2.4 Scaled/Wgted Val:  0.6/  0.6
 Heat content (KJ/cm2) :  25.4 Range:  3.6 to  75.9 Scaled/Wgted Val:  0.3/  0.3
 D200 (10**7s-1)       :  17.4 Range:-11.0 to 135.3 Scaled/Wgted Val:  0.2/  0.1
 % area w/pixels <-30 C:  59.0 Range: 41.4 to 100.0 Scaled/Wgted Val:  0.3/  0.1
 850-700 MB REL HUM (%):  66.4 Range: 57.6 to  96.8 Scaled/Wgted Val:  0.2/  0.0
 
 Prob of RI for 25 kt RI threshold=    32% is   2.5 times the sample mean(13.1%)
 Prob of RI for 30 kt RI threshold=    26% is   3.0 times the sample mean( 8.7%)
 Prob of RI for 35 kt RI threshold=    19% is   3.1 times the sample mean( 6.0%)
 Prob of RI for 40 kt RI threshold=    14% is   3.4 times the sample mean( 4.3%
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Re: EPAC: NORA - Tropical Storm

#26 Postby cycloneye » Fri Oct 09, 2015 9:34 pm

BULLETIN
TROPICAL STORM NORA ADVISORY NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182015
800 PM PDT FRI OCT 09 2015

...DEPRESSION BECOMES THE FOURTEENTH TROPICAL STORM OF THE EASTERN
NORTH PACIFIC HURRICANE SEASON...


SUMMARY OF 800 PM PDT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...11.3N 135.1W
ABOUT 1470 MI...2365 KM ESE OF SOUTH POINT HAWAII
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...W OR 275 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES



TROPICAL STORM NORA DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182015
800 PM PDT FRI OCT 09 2015

Deep convection has increased a little since the last advisory,
with the center located on the southeastern edge of the convective
mass due to light/moderate southeasterly shear over the cyclone.
The initial intensity is set to 35 kt based on the latest Dvorak
classifications from TAFB and SAB, marking the formation of
Tropical Storm Nora, the 14th tropical storm of the eastern North
Pacific season. Environmental conditions appear favorable for
continued steady strengthening for the next 72 hours, with the
cyclone moving over SSTs at or above 29C during that period and
light shear. By days 4 and 5 the SHIPS model and global model fields
show the shear increasing, which should result in weakening. The
new NHC forecast is largely an update of the previous one, and is
close to or a little above the SHIPS model through the period.

The initial motion estimate is 275/14, as Nora is being steered
quickly westward by a subtropical ridge to the north. A gradual
decrease in forward speed is forecast during the next 36 hours as
the ridge slowly weakens, and Nora should then turn west-
northwestward as a weakness develops around 145W. Nora is then
forecast to recurve between a deep-layer trough over the north-
central Pacific and a strengthening ridge to the southeast by the
end of the period. The track model guidance is in overall good
agreement on this scenario, and the new NHC forecast is close to a
blend of the GFS and ECMWF models through the period. The new
official forecast is a little north of the previous one through 48
hours, and then is a little to the left, showing a more gradual
recurvature following the latest trend in the guidance.

FORECAST POSITIONS AND MAX WINDS

INIT 10/0300Z 11.3N 135.1W 35 KT 40 MPH
12H 10/1200Z 11.6N 137.0W 40 KT 45 MPH
24H 11/0000Z 11.8N 139.5W 50 KT 60 MPH
36H 11/1200Z 11.9N 141.6W 60 KT 70 MPH
48H 12/0000Z 12.3N 143.1W 65 KT 75 MPH
72H 13/0000Z 13.0N 145.0W 80 KT 90 MPH
96H 14/0000Z 15.0N 145.0W 75 KT 85 MPH
120H 15/0000Z 18.5N 142.5W 65 KT 75 MPH

$$
Forecaster Brennan

NNNN
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#27 Postby Kingarabian » Sat Oct 10, 2015 1:42 am

Euro still doesn't like it. Continues to be more west and weaker.
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#28 Postby cycloneye » Sat Oct 10, 2015 6:54 am

TROPICAL STORM NORA DISCUSSION NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182015
200 AM PDT SAT OCT 10 2015

Nora has changed little in organization during the past several
hours. The low-level center continues to be near the southeastern
edge of the convection, and the strongest convection is currently
in outer bands well northwest of the center. This is likely due to
the effects of light southeasterly vertical wind shear. In
addition, recent ASCAT data suggests the circulation is elongated
north to south. Satellite intensity estimates are 35 kt from both
TAFB and SAB, and the ASCAT data also shows winds near 35 kt. Based
on this, the advisory intensity remains 35 kt.

Nora is now moving 285/14, with the cyclone continuing to be steered
by a deep-layer subtropical ridge to the north. The dynamical
models forecast the ridge to weaken during the next 36 hours, with
Nora moving generally westward with a decrease in forward speed.
After that time, the tropical cyclone is likely to turn northward
and probably recurve as a deep-layer trough over the north Pacific
breaks the subtropical ridge. The track guidance is tightly
clustered for the first 36 hours, but subsequently there is an
increased spread on where and how fast Nora will recurve. The ECMWF
shows a weaker Nora moving farther west and eventually turning
northward along 149W by 120 hours. The UKMET shows a stronger Nora
making an earlier recurvature with the storm near 19N 138W by 120
hours. The GFS lies between these models and is near the center of
the guidance envelope. The new track forecast is a little north of
the previous forecast for the first 48 hours, and then it is a
little west of the previous forecast after that time. The new track
is near the center of the guidance envelope and lies a little west
of the GFS after 72 hours.

Nora is expected to remain in an environment of light shear and
warm sea surface temperatures for the next 2-3 days, which should
allow strengthening. After that, the cyclone is expected to
encounter unfavorable conditions of strong southwesterly shear and
decreasing sea surface temperatures. Based on this, the new
intensity forecast follows the trend of the previous forecast in
calling to Nora to peak as a hurricane in about 72 hours and
subsequently weaken to a tropical storm by 120 hours. The new
forecast is in best agreement with the Florida State Superensemble.


FORECAST POSITIONS AND MAX WINDS

INIT 10/0900Z 11.6N 136.5W 35 KT 40 MPH
12H 10/1800Z 11.9N 138.3W 45 KT 50 MPH
24H 11/0600Z 12.1N 140.5W 50 KT 60 MPH
36H 11/1800Z 12.4N 142.3W 60 KT 70 MPH
48H 12/0600Z 12.7N 143.7W 65 KT 75 MPH
72H 13/0600Z 13.5N 145.5W 75 KT 85 MPH
96H 14/0600Z 16.0N 145.0W 70 KT 80 MPH
120H 15/0600Z 18.5N 142.5W 60 KT 70 MPH

$$
Forecaster Beven
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Re: EPAC: NORA - Tropical Storm

#29 Postby cycloneye » Sat Oct 10, 2015 9:43 am

TROPICAL STORM NORA DISCUSSION NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182015
800 AM PDT SAT OCT 10 2015

The satellite appearance of Nora has improved slightly during the
past several hours with deeper convection near the center and
increased banding features in the northwestward quadrant. The
initial intensity is raised to 40 kt as a compromise between the
TAFB and SAB satellite estimates.

Further strengthening seems likely over the next couple of days
while Nora remains in a low shear, warm water environment. The
models, however, generally show a lower peak intensity with Nora,
perhaps due to drier air in the mid-levels, so the new forecast will
reflect this trend. The most notable change to the forecast
is at day 3 and beyond when the global models are predicting the
vertical wind shear to increase earlier and be much stronger than
predicted yesterday for the cyclone. Intensity guidance is notably
lower during that period, with only the GFDL showing hurricane
strength. The latest NHC prediction is similar to the previous one
through 48 hours, then is reduced afterward by about 10 kt. That's
about the largest change I feel comfortable making at long range due
to continuity concerns, but most of the historically reliable
guidance is still below my new forecast.

Nora is moving westward at roughly 12 kt. The cyclone should move
to the west or west-northwest for the next couple of days while it
is steered by a ridge over the east-central Pacific. This
ridge is forecast to weaken during that time, which should result in
Nora slowing down and gradually gaining latitude. A mid-latitude
trough should help the ridge break down in a few days and turn Nora
northward, although there remains some spread in the guidance when
Nora will recurve. The GFS and HWRF models have joined the ECMWF
model in predicting a weaker Nora, which results in a delayed
northward turn. The official forecast is similar to the previous one
through 72 hours, then is shifted westward at long range in
accordance with the new guidance.



FORECAST POSITIONS AND MAX WINDS

INIT 10/1500Z 11.7N 137.2W 40 KT 45 MPH
12H 11/0000Z 11.9N 139.0W 45 KT 50 MPH
24H 11/1200Z 12.1N 140.9W 50 KT 60 MPH
36H 12/0000Z 12.3N 142.5W 60 KT 70 MPH
48H 12/1200Z 12.6N 143.7W 65 KT 75 MPH
72H 13/1200Z 13.6N 145.3W 65 KT 75 MPH
96H 14/1200Z 15.9N 145.4W 55 KT 65 MPH
120H 15/1200Z 18.0N 144.5W 45 KT 50 MPH

$$
Forecaster Blake
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Re: EPAC: NORA - Tropical Storm

#30 Postby cycloneye » Sat Oct 10, 2015 3:53 pm

TROPICAL STORM NORA DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182015
200 PM PDT SAT OCT 10 2015

Nora is small tropical cyclone with an irregular central dense
overcast and some banding features especially northwest of the
center. Microwave data show that the inner core has improved in
organization, with a mostly closed ring noted in the 37 GHz
channel. With the increasing inner core structure, the initial wind
speed is raised to 45 kt, at the higher end of the estimates near
the Dvorak value from TAFB. The initial 34-kt wind radii were
adjusted inward based on an ASCAT-A pass from 1826Z.

Over the next couple of days, the environment near the storm is
expected to generally be favorable for strengthening, with very warm
waters and low shear anticipated. However, some dry air aloft is
expected to temper the intensification, and only a gradual increase
in wind speed is expected at this time. Still, with the inner core
getting better organized, a faster rate of intensification is
possible, with the SHIPS-RI index showing a 25 percent chance of a
30-kt change over the next 24 hours. The intensity forecast will
remain close to the previous one in the first 48 hours, above most
of the guidance and closest to the GFDL and Florida State
Superensemble models. Global models are increasing the wind shear
near Nora quite a bit in a few days and keeping it high for the
remainder of the period. This will likely cause significant
weakening, and the NHC prediction is decreased a little bit at long
range, and is below the model consensus.

Nora continues moving westward at roughly 12 kt. There has been no
change to the synoptic pattern with a ridge expected to gradually
weaken to the north of the tropical cyclone over the next couple of
days. This pattern should result in Nora decelerating during that
time, while generally moving a little north of west. Thereafter,
the storm is expected to encounter a weakness in the ridge while a
mid-latitude trough digs north of Hawaii. These features should
turn Nora to the north and northeast, well east of the Hawaiian
Islands. Model guidance has shifted a bit to the south and west on
this model cycle, in better agreement overall on a later northward
turn. The NHC forecast is shifted westward through 96 hours to come
into better agreement with the consensus-based guidance.

FORECAST POSITIONS AND MAX WINDS

INIT 10/2100Z 11.8N 138.5W 45 KT 50 MPH
12H 11/0600Z 11.9N 140.1W 50 KT 60 MPH
24H 11/1800Z 12.0N 141.9W 55 KT 65 MPH
36H 12/0600Z 12.1N 143.3W 60 KT 70 MPH
48H 12/1800Z 12.3N 144.5W 65 KT 75 MPH
72H 13/1800Z 13.8N 146.0W 60 KT 70 MPH
96H 14/1800Z 16.0N 145.5W 50 KT 60 MPH
120H 15/1800Z 18.0N 144.0W 40 KT 45 MPH

$$
Forecaster Blake/Brennan

NNNN
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#31 Postby Yellow Evan » Sat Oct 10, 2015 6:13 pm

Looks beyond terrible, but seems to being building an inner core per microwave. At least the guidance is trending upward.
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Re: EPAC: NORA - Tropical Storm

#32 Postby cycloneye » Sat Oct 10, 2015 9:40 pm

TROPICAL STORM NORA DISCUSSION NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL EP182015
800 PM PDT SAT OCT 10 2015

Nora's satellite presentation continues to feature an irregular CDO
with little in the way of convective banding. The initial intensity
remains 45 kt based on a blend of the latest TAFB and SAB Dvorak
classifications. ASCAT data received around the time of the last
advisory suggested that Nora is a very small tropical cyclone, with
tropical storm force winds only extending outward up to 30 n mi in
the northern semicircle. An AMSR2 microwave image from the JAXA
GCOM-W2 satellite around 22Z clearly showed the low-level center on
the southeastern edge of the deep convection, but convection has
formed closer to the center since that time.

The near-storm environment should be favorable for some
strengthening in the next 48 hours or so, with warm waters and low
vertical shear, but there is some mid-tropospheric dry air in the
environment that could limit strengthening. After that time, the
vertical shear begins to increase as the cyclone recurves, and
steady weakening is forecast to begin after 72 hours. The NHC
forecast generally follows the trend of the previous one, but no
longer explicitly shows Nora reaching hurricane strength. However,
this is certainly still possible. The NHC prediction is close to the
FSU Superensemble through 36 hours and near the intensity consensus
after that time.

The ASCAT data and microwave fixes indicated that the center of
Nora was located a little southwest of the position in the previous
advisory, but the initial motion remains westward at 12 kt. The
synoptic reasoning for the track forecast has not changed, as Nora
will be steered westward at a decreasing forward speed for the next
36 to 48 hours by a weakening ridge to the north. After that time,
Nora should begin to recurve into a break in the ridge and then turn
northeastward by the end of the period under the influence of a
longwave trough over the north-central Pacific. The new NHC track
forecast has been adjusted to the south and west of the previous one
through 72 hours to account for the initial position and motion, and
is near the previous official forecast track after that time. The
NHC forecast lies between the latest ECMWF forecast and the TVCE
multi-model consensus.

With Nora moving into the central North Pacific basin, this will
be the last advisory from NHC. Future information on Nora can
be found in advisories issued by the Central Pacific Hurricane
Center beginning at 1100 PM HST (0900Z).

FORECAST POSITIONS AND MAX WINDS

INIT 11/0300Z 11.7N 139.9W 45 KT 50 MPH
12H 11/1200Z 11.8N 141.5W 50 KT 60 MPH
24H 12/0000Z 11.9N 143.2W 55 KT 65 MPH
36H 12/1200Z 12.0N 144.6W 60 KT 70 MPH
48H 13/0000Z 12.2N 145.6W 60 KT 70 MPH
72H 14/0000Z 14.0N 146.5W 55 KT 65 MPH
96H 15/0000Z 16.0N 145.8W 45 KT 50 MPH
120H 16/0000Z 17.5N 144.5W 35 KT 40 MPH

$$
Forecaster Brennan
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Re: EPAC: NORA - Tropical Storm

#33 Postby cycloneye » Sun Oct 11, 2015 5:57 am

TROPICAL STORM NORA DISCUSSION NUMBER 8
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP182015
1100 PM HST SAT OCT 10 2015

DEEP CONVECTION HAS INCREASED NEAR THE CENTER OF NORA DURING THE
PAST SEVERAL HOURS. DVORAK CURRENT INTENSITY ESTIMATES RANGED FROM
3.5/55 KT FROM HFO TO 2.5/35 KT FROM SAB...WHILE CIMSS ADT CAME IN
AT 51 KT. GIVEN THE IMPROVEMENT IN THE SATELLITE PRESENTATION...A
BLEND OF THESE INPUTS SUPPORTS RAISING THE INITIAL INTENSITY TO 50
KT.

SLOW INTENSIFICATION IS LIKELY DURING THE NEXT COUPLE OF DAYS...
FOLLOWED BY WEAKENING ON DAYS 3 THROUGH 5. AN UPPER LEVEL
ANTICYCLONE TO THE NORTHEAST OF NORA AND A WEAK UPPER LEVEL TROUGH
TO THE NORTHWEST ARE CREATING AN OUTFLOW CHANNEL TO THE
NORTHWEST...THOUGH SOUTHERLY WINDS ALOFT ARE INHIBITING OUTFLOW
ELSEWHERE AND PRODUCING VERTICAL WIND SHEAR OF AROUND 10 KT
ACCORDING TO SHIPS AND THE LATEST CIMSS ANALYSIS. THESE WINDS ALOFT
ARE EXPECTED TO DIMINISH DURING THE NEXT 24 HOURS AS THE UPPER
LEVEL TROUGH BRIEFLY RETREATS...AND THE SEA SURFACE TEMPERATURE
WILL REMAIN AROUND 29C ALONG THE FORECAST TRACK IN THE SHORT TERM.
AS A RESULT...SLOW INTENSIFICATION IS EXPECTED DURING THE NEXT
COUPLE OF DAYS. WEAKENING IS FORECAST TO BEGIN LATE MONDAY OR
TUESDAY AS A DEEP TROUGH DEVELOPING OVER HAWAII IMPARTS INCREASING
VERTICAL WIND SHEAR. THE INTENSITY FORECAST WAS CHANGED LITTLE FROM
THE PRIOR ADVISORY AND CLOSELY FOLLOWS THE TRENDS OF SHIPS AND ICON
WHILE PEAKING THE INTENSITY OF NORA SLIGHTLY HIGHER THAN THESE
GUIDANCE MEMBERS.

NORA CONTINUES TO MOVE WESTWARD...280 DEGREES...AT 11 KT. THIS
GENERAL MOTION IS EXPECTED TO CONTINUE INTO MONDAY AS NORA IS
STEERED BY A DEEP RIDGE CENTERED SEVERAL HUNDRED MILES TO THE
NORTH. A TURN TOWARD THE NORTHWEST IS EXPECTED TO OCCUR LATE MONDAY
AND TUESDAY AS THE DEEP TROUGH DEVELOPING OVER HAWAII CREATES A
WEAKNESS IN THE RIDGE TO THE NORTH OF NORA. NORA IS EXPECTED TO TURN
NORTH THEN EVENTUALLY NORTHEAST ON DAYS 3 THROUGH 5 AS THE SYSTEM
INCREASINGLY INTERACTS WITH THE TROUGH. WHILE THERE IS SOME
UNCERTAINTY AND MODEL SPREAD REGARDING THE EXACT TIMING OF THE
TURN...IT IS EXPECTED TO OCCUR SEVERAL HUNDRED MILES SOUTHEAST OF
HAWAII. THE FORECAST WAS SHIFTED SLIGHTLY WESTWARD FROM 48 HOURS AND
BEYOND AND IS CLOSE TO THE GFEX AND TVCN.



FORECAST POSITIONS AND MAX WINDS

INIT 11/0900Z 11.9N 141.1W 50 KT 60 MPH
12H 11/1800Z 12.0N 142.6W 55 KT 65 MPH
24H 12/0600Z 12.2N 144.2W 55 KT 65 MPH
36H 12/1800Z 12.4N 145.6W 60 KT 70 MPH
48H 13/0600Z 13.1N 146.7W 60 KT 70 MPH
72H 14/0600Z 14.7N 147.6W 55 KT 65 MPH
96H 15/0600Z 16.0N 147.4W 45 KT 50 MPH
120H 16/0600Z 17.0N 146.3W 35 KT 40 MPH

$$
FORECASTER WROE
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Re: EPAC: NORA - Tropical Storm

#34 Postby cycloneye » Sun Oct 11, 2015 9:54 am

TROPICAL STORM NORA DISCUSSION NUMBER 9
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP182015
500 AM HST SUN OCT 11 2015

THE SATELLITE PRESENTATION OF NORA CONTINUED TO IMPROVE
OVERNIGHT...WITH THUNDERSTORMS PERSISTING NEAR THE CENTER AND A BAND
OF DEEP CONVECTION DEVELOPING IN THE NORTHERN QUADRANT. AN ASCAT
PASS AT 0712 UTC RETURNED A MAXIMUM WIND RETRIEVAL OF 45 KT...WHICH
IS LIKELY AN UNDERESTIMATE GIVEN THE LOW BIAS OF ASCAT. A 1031 UTC
AMSR2 PASS SHOWED A DEVELOPING EYE WALL STRUCTURE ALOFT IN THE 89
GHZ CHANNEL THAT APPEARS TO BE TILTED NORTHEASTWARD WITH HEIGHT...
WHILE THE 36 GHZ CHANNEL SHOWED NO SUCH STRUCTURE AT LOWER LEVELS.
DVORAK CURRENT INTENSITY ESTIMATES CAME IN AT 3.5/55 KT FROM HFO
AND 3.0/50 KT FROM SAB AND JTWC...WHILE CIMSS ADT WAS UP TO NEARLY
60 KT. A BLEND OF THESE INPUTS SUPPORTS RAISING THE INITIAL
INTENSITY TO 55 KT.

ADDITIONAL INTENSIFICATION IS EXPECTED DURING THE NEXT 24 HOURS...
WITH NORA NOW FORECAST TO BECOME A HURRICANE. AN UPPER LEVEL
ANTICYCLONE TO THE NORTHEAST OF NORA AND A WEAK UPPER LEVEL TROUGH
TO THE NORTHWEST ARE MAINTAINING AN OUTFLOW CHANNEL TO THE
NORTHWEST...THOUGH SOUTHERLY WINDS ALOFT CONTINUE TO INHIBIT
OUTFLOW ELSEWHERE AND PRODUCE VERTICAL WIND SHEAR OF 10 TO 15 KT
ACCORDING TO SHIPS AND THE LATEST CIMSS ANALYSIS. THESE WINDS ALOFT
ARE EXPECTED TO DIMINISH SLIGHTLY TODAY AND TONIGHT AS THE UPPER
LEVEL TROUGH BRIEFLY RETREATS...AND THE SEA SURFACE TEMPERATURE
WILL REMAIN AROUND 29C ALONG THE FORECAST TRACK IN THE SHORT TERM.
THIS WILL RESULT IN A WINDOW FOR ADDITIONAL INTENSIFICATION.
WEAKENING IS FORECAST TO BEGIN LATE MONDAY OR TUESDAY AS A DEEP
TROUGH DEVELOPING OVER HAWAII IMPARTS INCREASING VERTICAL WIND
SHEAR. THE LATEST FORECAST CALLS FOR MORE INTENSIFICATION IN THE
SHORT TERM THAN THE LAST PACKAGE. THE OFFICIAL FORECAST IS ON THE
HIGH END OF THE GUIDANCE ENVELOPE IN THE SHORT TERM...CLOSE TO BUT
SLIGHTLY HIGHER THAN SHIPS AND LGEM THROUGH 48 HOURS...AND IS NEAR
ICON ON DAYS 3 THROUGH 5 AS NORA WEAKENS.

NORA CONTINUES TO MOVE WESTWARD...280 DEGREES...AT 11 KT. THIS
GENERAL MOTION IS EXPECTED TO CONTINUE INTO MONDAY AS NORA IS
STEERED BY A DEEP RIDGE CENTERED SEVERAL HUNDRED MILES TO THE
NORTH. A TURN TOWARD THE NORTHWEST IS EXPECTED TO OCCUR LATE MONDAY
AND TUESDAY AS THE DEEP TROUGH DEVELOPING OVER HAWAII CREATES A
WEAKNESS IN THE RIDGE TO THE NORTH OF NORA. NORA IS EXPECTED TO TURN
NORTH THEN EVENTUALLY NORTHEAST ON DAYS 3 THROUGH 5 AS THE SYSTEM
INCREASINGLY INTERACTS WITH THE TROUGH. WHILE THERE IS SOME
UNCERTAINTY AND MODEL SPREAD REGARDING THE EXACT TIMING OF THE
TURN...IT IS EXPECTED TO OCCUR SEVERAL HUNDRED MILES SOUTHEAST OF
HAWAII. THE FORECAST WAS AGAIN SHIFTED SLIGHTLY WESTWARD FROM 48
HOURS THROUGH DAY 5 AND IS CLOSE TO THE ECMWF...GFS ENSEMBLE...AND
TVCN.




FORECAST POSITIONS AND MAX WINDS

INIT 11/1500Z 12.2N 142.4W 55 KT 65 MPH
12H 12/0000Z 12.4N 143.6W 60 KT 70 MPH
24H 12/1200Z 12.7N 145.3W 65 KT 75 MPH
36H 13/0000Z 13.1N 146.6W 65 KT 75 MPH
48H 13/1200Z 13.7N 147.7W 60 KT 70 MPH
72H 14/1200Z 15.3N 148.6W 55 KT 65 MPH
96H 15/1200Z 16.8N 148.2W 45 KT 50 MPH
120H 16/1200Z 17.7N 147.6W 35 KT 40 MPH

$$
FORECASTER WROE
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#35 Postby Yellow Evan » Sun Oct 11, 2015 2:44 pm

11/1730 UTC 12.6N 142.7W T4.0/4.0 NORA -- Central Pacific

Microwave images have been very off and on, with some showing a closed eyewall and some not (maybe due to the small size of the eye), but the structure has degraded some. Nevertheless, this is likely nearly a hurricane.

The long-awaited opening of a south-southwesterly outflow channel has yet to happen. Thinking this become a hurricane, but anything more is up in the air.
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Re: EPAC: NORA - Tropical Storm

#36 Postby supercane » Sun Oct 11, 2015 9:52 pm

WTPA44 PHFO 112040
TCDCP4

TROPICAL STORM NORA DISCUSSION NUMBER 10
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP182015
1100 AM HST SUN OCT 11 2015

SATELLITE PRESENTATION CONSISTS OF AN IRREGULAR 140 TO 150 NM
DIAMETER CENTRAL DENSE OVERCAST AREA WITH A PROMINENT RAIN BAND
ALONG THE NORTHERN FLANK EXTENDING EASTWARD. A SINGLE OUTFLOW
CHANNEL EXTENDS TO THE NORTH NORTHWEST. A 1642 UTC SSMIS MICROWAVE
PASS SHOWED EYEWALL DEVELOPMENT ALONG THE WESTERN HALF OF THE LOW
LEVEL CIRCULATION CENTER...LLCC...WHICH WAS EASIER TO SEE AT 85 GHZ
THAN 37 GHZ. OVERALL ORGANIZATION APPEARS TO HAVE IMPROVED A BIT
SINCE LAST NIGHT. SUBJECTIVE DVORAK SATELLITE INTENSITY ESTIMATES
RANGED FROM 3.5...55 KT...FROM PHFO AND JTWC...TO 4.0...65 KT...FROM
SAB. UW-CIMSS ADT WAS 3.9...63 KT. WE WILL TAKE A BLEND OF THESE
ESTIMATES AND ASSIGN AN INITIAL INTENSITY OF 60 KT FOR THIS
ADVISORY...REPRESENTING SOME STRENGTHENING SINCE EARLIER THIS
MORNING.

NORA APPEARS TO BE TAKING A RATHER WOBBLY TRACK GENERALLY TOWARD
THE WEST NORTHWEST. LONG TERM MOTION...OVER THE PAST 12 TO 24
HOURS...IS ABOUT 290/12 KT. HOWEVER...SHORT TERM MOTION IS MORE
LIKE 305/12 KT. SINCE THE 1800 UTC ANALYSIS CYCLE...NORA APPEARS TO
HAVE RESUMED A MORE WESTERLY MOTION ONCE AGAIN. UNFORTUNATELY...THE
ASSIGNED INITIAL MOTION OF 295/12 KT...A COMPROMISE OF SHORT AND
LONG TERM MOTION...IMMEDIATELY TAKES THIS SYSTEM TO THE RIGHT OF
THE PREVIOUS TRACK AND JUST OUTSIDE THE RELIABLE TRACK GUIDANCE
ENVELOPE THROUGH 36 HOURS. THE FINAL FORECAST TRACK FALLS BACK
WITHIN THIS ENVELOPE BY 48 HOURS...THEN FOLLOWS THE TVCN CONSENSUS
TRACK THROUGH EXPECTED RECURVATURE. THIS REPRESENTS A FORECAST
TRACK ADJUSTMENT TO THE RIGHT OF THE PREVIOUS ONE AT ALL TAU. THE
MAIN TRACK FORECAST CHALLENGE REMAINS THE TIMING OF RECURVATURE AS
DEEP TROUGHING NORTH OF THE MAIN HAWAIIAN ISLANDS MOVES EASTWARD AND
WEAKENS THE RIDGE NORTH OF NORA...THEN SCOOPS NORA NORTHEASTWARD OUT
OF THE DEEP TROPICS. THIS TIMING VARIES FROM MODEL TO MODEL...AND
FROM RUN TO RUN...SO EXPECT FUTURE TRACK CHANGES AS GUIDANCE
GRAPPLES WITH THE EFFECTS OF THE TROUGH. IN SPITE OF THIS
UNCERTAINTY...ALL OF THE GUIDANCE EITHER RECURVES NORA NORTHEASTWARD
FAR FROM HAWAII...OR DECAPITATES NORA AND SHOVES THE REMNANTS WEST
SOUTHWESTWARD WITHIN THE TRADES.

THERE IS A SMALL WINDOW FOR ADDITIONAL DEVELOPMENT AS SHEAR REMAINS
RELATIVELY LOW AND SEA SURFACE TEMPERATURES ACROSS THE FORECAST
TRACK REMAIN NEAR 29C. WE FORECAST NORA WILL REACH HURRICANE
STRENGTH IN 12 HOURS...MAINTAIN THIS STRENGTH THROUGH 24
HOURS...THEN GRADUALLY WEAKEN AS SHEAR BEGINS TO INCREASE WITH THE
APPROACH OF THE DEEP TROUGH. THIS IS IN LINE WITH SHIPS GUIDANCE
THROUGH 72 HOURS. HOWEVER...WE KEEP NORA AT MINIMAL TROPICAL STORM
STRENGTH THROUGH 120 HOURS WHILE SHIPS DISSIPATES IT. THE FORECAST
WEAKENING TREND FOLLOWS...BUT IS JUST BELOW...THE TRENDS DEPICTED IN
GFS AND ECMWF.


FORECAST POSITIONS AND MAX WINDS

INIT 11/2100Z 12.9N 143.2W 60 KT 70 MPH
12H 12/0600Z 13.4N 144.5W 65 KT 75 MPH
24H 12/1800Z 13.9N 146.0W 65 KT 75 MPH
36H 13/0600Z 14.5N 147.0W 60 KT 70 MPH
48H 13/1800Z 15.4N 147.6W 55 KT 65 MPH
72H 14/1800Z 16.6N 147.6W 50 KT 60 MPH
96H 15/1800Z 17.9N 147.0W 45 KT 50 MPH
120H 16/1800Z 19.4N 146.2W 35 KT 40 MPH

$$
FORECASTER POWELL

------------------------------------------------------------

WTPA44 PHFO 120240
TCDCP4

TROPICAL STORM NORA DISCUSSION NUMBER 11
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP182015
500 PM HST SUN OCT 11 2015

NORA IS A COMPACT TROPICAL SYSTEM...AND THE CENTRAL DENSE OVERCAST
AREA HAS BECOME SMALLER THIS AFTERNOON. LOW CLOUD LINES APPEAR TO
PLACE THE LOW LEVEL CIRCULATION CENTER...LLCC...BENEATH THE EASTERN
EDGE OF DEEPEST CONVECTION. A 2339 UTC SSMI MICROWAVE PASS...WHILE
NOT CONCLUSIVE...MARGINALLY SUPPORTS THE INITIAL POSITION...BUT
CONFIDENCE IS NOT VERY HIGH WITHOUT AN INFRARED WARM SPOT OR A
VISIBLE EYE. THIS SAME SSMI PASS SHOWED A LACK OF AN EYEWALL ACROSS
THE EASTERN SEMICIRCLE. SUBJECTIVE DVORAK SATELLITE INTENSITY
ESTIMATES RANGED FROM 3.5...55 KT...FROM JTWC TO 4.0...65 KT...FROM
PHFO AND SAB. UW-CIMSS ADT REMAINED 3.9...63 KT. NORA LOOKS NO
BETTER ORGANIZED THAN IT DID THIS MORNING AND...WITH NO
COMPLETE EYEWALL DEPICTED IN MICROWAVE IMAGERY...WE WILL HOLD THE
INITIAL INTENSITY AT 60 KT FOR THIS ADVISORY.

ANIMATION AND SUCCESSIVE SSMI PASSES SEEM TO SHOW THAT NORA IS
MAINTAINING A MORE NORTHERLY TRACK THIS AFTERNOON THAN IT WAS
OVERNIGHT. INITIAL MOTION IS SET AT 300/08 KT...NOTICEABLY SLOWER
THAN BEFORE. TRACK GUIDANCE CONTINUES TO DEPICT NORA MOVING
WEST NORTHWESTWARD THROUGH 36 HOURS...ALONG THE SOUTHWEST FLANK OF
MID-LEVEL RIDGING TO THE NORTHEAST OF THIS SYSTEM. GUIDANCE THEN
RECURVES NORA NORTHWARD ON DAYS TWO AND THREE...THEN NORTHEASTWARD
ON DAYS FOUR AND FIVE AS A DEEP TROUGH NORTH OF HAWAII MOVES
EAST...WEAKENS THE RIDGE...AND SCOOPS NORA OUT OF THE DEEP TROPICS.
THE SPREAD IN TRACK GUIDANCE IS DUE TO DIFFERENCES IN INITIAL
MOTION AND FORWARD SPEED DURING RECURVATURE. IN SPITE OF THIS
UNCERTAINTY...ALL OF THE GUIDANCE EITHER RECURVES NORA NORTHEASTWARD
FAR FROM HAWAII...OR DECAPITATES NORA AND SHOVES THE REMNANTS WEST
SOUTHWESTWARD WITHIN THE TRADES.

INTENSITY GUIDANCE SHOWS THE WINDOW FOR STRENGTHENING WILL LIKELY
SLAM SHUT IN 12 HOURS. SHEAR ACROSS NORA HAS INCREASED INTO THE 15
TO 20 KT RANGE THIS AFTERNOON BUT...WITH SEA SURFACE TEMPERATURES
NEAR 29C...SHIPS AND LGEM ALLOW FOR A SMALL INTENSITY INCREASE
THROUGH TONIGHT. GUIDANCE THEN AGREES ON STEADY WEAKENING THROUGH
120 HOURS...WITH SHIPS DISSIPATING NORA AT 96 HOURS. WE WILL
CONTINUE TO PEAK NORA AT 65 KT...AS A HURRICANE...IN 12 HOURS.
HOWEVER...WE NOW FORECAST CONTINUED WEAKENING THEREAFTER.


FORECAST POSITIONS AND MAX WINDS

INIT 12/0300Z 13.5N 143.8W 60 KT 70 MPH
12H 12/1200Z 14.0N 144.9W 65 KT 75 MPH
24H 13/0000Z 14.7N 146.1W 60 KT 70 MPH
36H 13/1200Z 15.4N 146.9W 60 KT 70 MPH
48H 14/0000Z 16.1N 147.3W 55 KT 65 MPH
72H 15/0000Z 17.9N 147.1W 50 KT 60 MPH
96H 16/0000Z 20.4N 145.4W 45 KT 50 MPH
120H 17/0000Z 22.6N 143.3W 35 KT 40 MPH

$$
FORECASTER POWELL
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Re: EPAC: NORA - Tropical Storm

#37 Postby cycloneye » Mon Oct 12, 2015 5:34 am

TROPICAL STORM NORA DISCUSSION NUMBER 12
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP182015
1100 PM HST SUN OCT 11 2015

THE SATELLITE PRESENTATION OF NORA HAS DEGRADED SIGNIFICANTLY SINCE
THE LAST ADVISORY PACKAGE...WITH INFRARED IMAGERY INDICATING
WARMING CLOUD TOPS INFLUENCED BY INCREASING SOUTHERLY WIND SHEAR.
THIS IS EVIDENT BY THE LATEST UW-CIMSS VERTICAL WIND SHEAR ANALYSIS
SHOWING 28 KNOTS OF SHEAR FROM 195 DEGREES...WITH SHIPS INDICATING
14 KNOTS OF SHEAR FROM 215 DEGREES. A 12/0353Z SSMIS WAS EXTREMELY
HELPFUL IN LOCATING THE CENTER OF NORA...AND HAS RESULTED IN A
SIGNIFICANT SOUTHWARD ADJUSTMENT TO THE TRACK OF THIS SYSTEM. BASED
ON THE NEW CENTER POSITION...IT IS CLEAR THAT SHEAR IS TAKING A TOLL
ON THE SYSTEM...WITH THE LOW LEVEL CIRCULATION CENTER (LLCC) NOW AT
THE EDGE OF THE DEEP CONVECTION. THE LATEST FIXES FROM PHFO AND SAB
CAME IN AT 4.0/65 KNOTS...JTWC CAME IN AT 3.5/55 KNOTS. THE ADT
VALUE WAS 4.0 AS WELL...BUT INITIALIZED THE CENTER AT 13.7N
LATITUDE...WITHIN THE DEEP CONVECTION...AND AS A RESULT IS LIKELY
OVER ESTIMATING THE CURRENT INTENSITY. THE INTENSITY FOR THIS
ADVISORY PACKAGE WILL BE HELD AT 60 KNOTS...WHICH IS A COMPROMISE OF
THE FIXES PROVIDED BY THE VARIOUS AGENCIES AND TAKES INTO ACCOUNT
THE INFLUENCE OF THE INCREASING SOUTHERLY SHEAR AND LOCATION OF THE
LLCC. BASED ON RE-ANALYSIS OF NORA/S TRACK THROUGH THE DAY...THE
INITIAL MOTION WILL BE SET AT 285 DEGREES AT 7 KNOTS.

NORA IS CURRENTLY BEING STEERED TO THE WEST-NORTHWEST ON THE
SOUTHWESTERN PERIPHERY OF A LARGE UPPER LEVEL RIDGE LOCATED
NORTHEAST OF THE SYSTEM. THIS MOTION IS EXPECTED TO CONTINUE FOR THE
NEXT DAY OR SO WITH A SHIFT TOWARD A MORE NORTHWARD TRACK TUESDAY
AND WEDNESDAY AS AN UPPER LEVEL TROUGH APPROACHES FROM THE WEST.
WITH THE APPROACH OF THE UPPER LEVEL TROUGH...SHEAR WILL INCREASE
SIGNIFICANTLY OVER THE SYSTEM...WITH SHIPS GUIDANCE SHOWING 30 TO 35
KNOTS OF WEST-SOUTHWESTERLY VERTICAL WIND SHEAR OVER THE SYSTEM BY
WEDNESDAY NIGHT. THE INCREASING SHEAR WILL LIKELY RESULT IN A LOSS
OF ALL DEEP CONVECTION NEAR THE LLCC AND ALLOW THE SYSTEM TO BE
STEERED BY THE LOW LEVEL TRADE WIND FLOW AND OFF TO THE WEST. THE
LATEST OFFICIAL FORECAST TRACK FROM CPHC HAS BEEN SHIFTED TO THE
SOUTH AND WEST OF THE PREVIOUS OFFICIAL FORECAST...AND IS VERY CLOSE
TO GFEX...TVCN AND FSSE GUIDANCE TRACKS. THIS IS LARGELY DUE TO A
RE-POSITIONING OF THE SYSTEM TO THE SOUTH OF THE PREVIOUS ADVISORY
POSITION AND A MORE WESTWARD INITIAL MOVEMENT.

SLOW WEAKENING OF NORA IS EXPECTED DURING THE NEXT SEVERAL DAYS AS
VERTICAL WIND SHEAR INCREASES. THE OFFICIAL INTENSITY FORECAST WILL
HOLD...PERHAPS GENEROUSLY GIVEN THE CURRENT SATELLITE
PRESENTATION...THE INTENSITY AT 60 KNOTS THROUGH MONDAY MORNING.
SLOW WEAKENING IS THEN FORECAST THROUGH WEDNESDAY...AS INCREASING
UPPER FORCING FROM THE APPROACHING UPPER LEVEL TROUGH MAY ALLOW
ENOUGH OF AN INCREASE IN DEEP CONVECTION NEAR THE CENTER TO HOLD THE
INTENSITY OF THE SYSTEM UP...SIMILAR TO WHAT HAS OCCURRED WITH OTHER
SYSTEMS THIS SEASON IN THE NORTH-CENTRAL PACIFIC. SHEAR SHOULD
EVENTUALLY OVER POWER ANY CONTRIBUTION FROM UPPER LEVEL DYNAMIC
SUPPORT WEDNESDAY NIGHT...WITH STEADY WEAKENING EXPECTED THROUGH 120
HOURS. BASED ON THE LATEST INTENSITY FORECAST...NORA IS EXPECTED TO
DROP BELOW TROPICAL STORM STRENGTH THURSDAY NIGHT OR FRIDAY.




FORECAST POSITIONS AND MAX WINDS

INIT 12/0900Z 12.6N 144.5W 60 KT 70 MPH
12H 12/1800Z 12.9N 145.6W 60 KT 70 MPH
24H 13/0600Z 13.5N 146.9W 55 KT 65 MPH
36H 13/1800Z 14.4N 148.1W 50 KT 60 MPH
48H 14/0600Z 15.4N 148.6W 50 KT 60 MPH
72H 15/0600Z 17.3N 148.1W 45 KT 50 MPH
96H 16/0600Z 18.0N 148.5W 35 KT 40 MPH
120H 17/0600Z 18.5N 149.5W 30 KT 35 MPH

$$
FORECASTER JELSEMA/HOUSTON
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Yellow Evan
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#38 Postby Yellow Evan » Mon Oct 12, 2015 7:46 am

After looking at microwae, this seems to have peaked around 12-18z where the storm had a closed eyewall. Likely around 55 knots now, but may have been a hurricane then. Seems to me the the dreaded mid-level shear is taking toll.
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Re: EPAC: NORA - Tropical Storm

#39 Postby wxman57 » Mon Oct 12, 2015 9:09 am

Looks rather weak, to me. Center is displaced well SW of the convection (if it still exists). Shear is hitting it hard. An ASCAT pass would be helpful...
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Re: EPAC: NORA - Tropical Storm

#40 Postby cycloneye » Mon Oct 12, 2015 9:52 am

TROPICAL STORM NORA DISCUSSION NUMBER 13
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP182015
500 AM HST MON OCT 12 2015

THE LATEST INFRARED SATELLITE IMAGERY CLEARLY SHOWS THE LOW LEVEL
CIRCULATION CENTER (LLCC) OF NORA THIS MORNING. ALTHOUGH SOME NEW
CONVECTIVE DEVELOPMENT HAS BEEN NOTED OVER THE PAST HOUR OR
TWO...THE LLCC REMAINS LARGELY DEVOID OF DEEP CONVECTION. NORA
REMAINS UNDER THE INFLUENCE OF STRENGTHENING WIND SHEAR...WITH THE
LATEST UW-CIMSS VERTICAL WIND SHEAR ANALYSIS SHOWING 32 KNOTS OF
SHEAR FROM 205 DEGREES...AND SHIPS INDICATING 21 KNOTS OF SHEAR FROM
225 DEGREES. THE LATEST FIXES FROM PHFO AND JTWC CAME IN AT 3.5/55
KNOTS...SAB CAME IN AT 3.0/45 KNOTS. THE ADT VALUE WAS 4.0/65
KNOTS...BUT LIKELY CONTINUES TO SUFFER FROM THE ERROR IN CENTER
POSITION LAST EVENING...AND AS A RESULT IS OVER ESTIMATING CURRENT
INTENSITY. THE INTENSITY FOR THE 15Z ADVISORY PACKAGE WILL BE
LOWERED TO 55 KNOTS...BASED ON THE LATEST FIXES PROVIDED BY THE
VARIOUS AGENCIES AND ACCOUNTING FOR THE INFLUENCE OF THE INCREASING
SOUTH-SOUTHWESTERLY SHEAR. THE INITIAL MOTION BASED ON FIXES FROM
THE VARIOUS AGENCIES...MICROWAVE IMAGERY AND SATELLITE INTERPOLATION
WILL BE SET AT 285 DEGREES AT 8 KNOTS.

NORA IS CURRENTLY BEING STEERED TO THE WEST-NORTHWEST ON THE
SOUTHWESTERN PERIPHERY OF A LARGE UPPER LEVEL RIDGE LOCATED
NORTHEAST OF THE SYSTEM. THIS MOTION IS EXPECTED TO CONTINUE
THROUGH TONIGHT WITH A SHIFT TOWARD A MORE NORTHWARD TRACK TUESDAY
THROUGH WEDNESDAY AS AN UPPER LEVEL TROUGH APPROACHES FROM THE WEST
AND BEGINS TO INFLUENCE THE SYSTEM. WITH THE APPROACH OF THE UPPER
LEVEL TROUGH...SHEAR WILL INCREASE SIGNIFICANTLY OVER NORA...WITH
SHIPS GUIDANCE SHOWING 30 TO 35 KNOTS OF WEST-SOUTHWESTERLY VERTICAL
WIND SHEAR OVER THE SYSTEM BY TUESDAY NIGHT. THE INCREASING SHEAR
WILL LIKELY RESULT IN A LOSS OF ALL DEEP CONVECTION NEAR THE LLCC
BY WEDNESDAY NIGHT...ALLOWING THE SYSTEM TO BE STEERED BY THE LOW
LEVEL TRADE WIND FLOW AND OFF TO THE WEST. THE LATEST OFFICIAL
FORECAST TRACK FROM CPHC HAS BEEN SHIFTED SLIGHTLY SOUTH AND WEST OF
THE PREVIOUS OFFICIAL FORECAST...AND IS VERY CLOSE TO THE GFEX AND
TVCN GUIDANCE TRACKS.

SLOW WEAKENING OF NORA IS EXPECTED DURING THE NEXT SEVERAL DAYS AS
VERTICAL WIND SHEAR INCREASES. THE OFFICIAL INTENSITY FORECAST SHOWS
GRADUAL WEAKENING THROUGH WEDNESDAY...AS FAVORABLE SEA SURFACE
TEMPERATURES (SSTS) AROUND 28 TO 29C ALONG WITH INCREASING UPPER
FORCING FROM THE APPROACHING UPPER LEVEL TROUGH MAY ALLOW ENOUGH OF
AN INCREASE IN DEEP CONVECTION NEAR THE CENTER TO HOLD THE INTENSITY
OF THE SYSTEM UP...SIMILAR TO WHAT HAS OCCURRED WITH OTHER SYSTEMS
THIS SEASON IN THE NORTH-CENTRAL PACIFIC. SHEAR SHOULD EVENTUALLY
OVER POWER ANY CONTRIBUTION FROM THE FAVORABLE SSTS AND UPPER LEVEL
DYNAMIC SUPPORT WEDNESDAY NIGHT...WITH STEADY WEAKENING EXPECTED
THROUGH 120 HOURS. BASED ON THE LATEST INTENSITY FORECAST...NORA IS
EXPECTED TO DROP BELOW TROPICAL STORM STRENGTH WEDNESDAY NIGHT OR
THURSDAY AND BECOME A POST TROPICAL REMNANT LOW BY THURSDAY NIGHT.






FORECAST POSITIONS AND MAX WINDS

INIT 12/1500Z 12.7N 145.6W 55 KT 65 MPH
12H 13/0000Z 13.0N 146.8W 50 KT 60 MPH
24H 13/1200Z 13.5N 148.1W 45 KT 50 MPH
36H 14/0000Z 14.5N 149.0W 40 KT 45 MPH
48H 14/1200Z 15.5N 149.3W 40 KT 45 MPH
72H 15/1200Z 17.4N 149.3W 35 KT 40 MPH
96H 16/1200Z 18.0N 150.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
120H 17/1200Z 17.5N 151.5W 25 KT 30 MPH...POST-TROP/REMNT LOW

$$
FORECASTER JELSEMA/HOUSTON
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