EPAC: SIMON - Post-Tropical

[supercane4867]

12z GFS and HWRF both show Simon hitting Baja as a potent hurricane

[zeehag]

excuse me , but isnt the letter S the 19th letter of alphabet, making this not the 18th named one, but the 19th.. someone in nhc cannot add?? perhaps....

[South Texas Storms]

excuse me , but isnt the letter S the 19th letter of alphabet, making this not the 18th named one, but the 19th.. someone in nhc cannot add?? perhaps....

They don't use the letter "Q" for naming tropical cyclones.

[cycloneye]

BULLETIN
TROPICAL STORM SIMON ADVISORY NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL EP192014
200 PM PDT THU OCT 02 2014

...SIMON STRENGTHENS AND TURNS MORE WESTWARD...


SUMMARY OF 200 PM PDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...18.3N 108.0W
ABOUT 245 MI...395 KM W OF MANZANILLO MEXICO
ABOUT 340 MI...550 KM SSE OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...998 MB...29.47 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 200 PM PDT...2100 UTC...THE CENTER OF TROPICAL STORM SIMON WAS
LOCATED NEAR LATITUDE 18.3 NORTH...LONGITUDE 108.0 WEST. SIMON IS
NOW MOVING TOWARD THE WEST NEAR 9 MPH...15 KM/H. A GENERAL
WESTWARD MOTION IS EXPECTED TONIGHT AND FRIDAY...WITH A TURN TOWARD
THE WEST-NORTHWEST OR NORTHWEST EXPECTED ON SATURDAY. ON THE
FORECAST TRACK...THE CENTER OF SIMON SHOULD PASS NEAR SOCORRO
ISLAND ON FRIDAY.

MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 50 MPH...85 KM/H...
WITH HIGHER GUSTS. ADDITIONAL STRENGTHENING IS FORECAST DURING THE
NEXT 48 HOURS...AND SIMON COULD BECOME A HURRICANE FRIDAY NIGHT OR
SATURDAY.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 45 MILES...75 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 998 MB...29.47 INCHES.


HAZARDS AFFECTING LAND
----------------------
RAINFALL...SIMON IS EXPECTED TO PRODUCE RAINFALL AMOUNTS OF 3 TO 5
INCHES WITH ISOLATED AMOUNTS AROUND 8 INCHES THROUGH FRIDAY ACROSS
WESTERN GUERRERO AND MICHOACAN...COLIMA...WESTERN JALISCO AND
NAYARIT IN WESTERN MEXICO. THESE RAINS COULD CAUSE FLASH FLOODING
AND MUD SLIDES.

SURF...SWELLS GENERATED BY SIMON ARE AFFECTING PORTIONS OF THE
SOUTHWESTERN COAST OF MEXICO. THESE SWELLS ARE LIKELY TO CAUSE
LIFE-THREATENING SURF AND RIP CURRENT CONDITIONS. PLEASE CONSULT
PRODUCTS FROM YOUR LOCAL WEATHER OFFICE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...800 PM PDT.

$$
FORECASTER BEVEN



TROPICAL STORM SIMON DISCUSSION NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL EP192014
200 PM PDT THU OCT 02 2014

The center of Simon has either re-formed or has made a large wobble
during the past few hours, as a TRMM overpass at 1827 UTC suggests
the center is well southwest of the position seen in earlier SSM/IS
overpasses. This requires a southward adjustment of the initial
position. The new advisory position is still north of the TRMM
position, and an additional adjustment may be required later if no
subsequent northward wobble occurs. The initial intensity is
increased to 45 kt based on satellite intensity estimates from TAFB
and SAB, along with CIMSS ADT and CIRA AMSU estimates.

The initial motion is a rather uncertain 280/8. For the next day
or so, mid-level ridging to the north and northeast of the cyclone
should steer Simon generally westward to west-northwestward. From
24-72 hours, the cyclone should turn more northward as it approaches
the western end of the ridge. The guidance continues to show
significant divergence after that. The GFS, GFDL, and HWRF, show a
northeastward turn between 72-120 hours and bring Simon close to
Baja California in 96-120 hours. On the other hand, the the ECMWF
and UKMET show a generally northwestward motion that keeps the
center well away from land. The track forecast compromises between
these extremes by showing a slow northward motion by 120 hours. The
new forecast is shifted to the south and west of the previous
forecast based on current trends, and it is in best overall
agreement with the Florida State Superensemble.

Simon is forecast to remain in a light vertical wind shear
environment and over sea surface temperatures of 28-29C for the
next 48 hours, which should allow at least steady strengthening.
After that, movement over cooler water should cause weakening. The
new intensity forecast is increased over the previous forecast in
best overall agreement with the SHIPS model, and it lies near the
upper edge of the intensity guidance. An alternative forecast
scenario is that rapid intensification begins in the next 12-24
hours, with Simon becoming significantly stronger than forecast.
This scenario is supported by above average probabilities in the
Rapid Intensification Index of the SHIPS model, and by the TRMM
data, which suggests Simon is developing a small inner core.


FORECAST POSITIONS AND MAX WINDS

INIT 02/2100Z 18.3N 108.0W 45 KT 50 MPH
12H 03/0600Z 18.6N 109.2W 50 KT 60 MPH
24H 03/1800Z 19.0N 111.0W 60 KT 70 MPH
36H 04/0600Z 19.7N 112.6W 70 KT 80 MPH
48H 04/1800Z 20.7N 114.1W 75 KT 85 MPH
72H 05/1800Z 22.5N 115.5W 70 KT 80 MPH
96H 06/1800Z 24.0N 116.0W 60 KT 70 MPH
120H 07/1800Z 25.0N 116.0W 45 KT 50 MPH

$$
Forecaster Beven

[Yellow Evan]

excuse me , but isnt the letter S the 19th letter of alphabet, making this not the 18th named one, but the 19th.. someone in nhc cannot add?? perhaps....

It is the 19th storm technically due to Wali.

[Yellow Evan]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.2.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 02 OCT 2014 Time : 201500 UTC
Lat : 18:18:33 N Lon : 107:54:04 W


CI# /Pressure/ Vmax
3.1 / 997.2mb/ 47.0kt


Final T# Adj T# Raw T#
3.1 3.3 3.9

Center Temp : -68.8C Cloud Region Temp : -63.5C

Scene Type : UNIFORM CDO CLOUD REGION

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : EAST PACIFIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : 0.7T/6hr
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 36km
- Environmental MSLP : 1010mb

Satellite Name : GOES13
Satellite Viewing Angle : 43.0 degrees

[Yellow Evan]

I fear the NHC is way too far west. We saw the same thing happen with Odile and Norbert. Now that's intensifying, it's more likely to get picked up by the trough. We see this regularly with Baja systems.

[cycloneye]

BULLETIN
TROPICAL STORM SIMON ADVISORY NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL EP192014
800 PM PDT THU OCT 02 2014

...SIMON COULD BECOME A HURRICANE ON FRIDAY...


SUMMARY OF 800 PM PDT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...18.1N 108.2W
ABOUT 260 MI...420 KM SW OF PUERTO VALLARTA MEXICO
ABOUT 350 MI...560 KM SSE OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 5 MPH...7 KM/H
MINIMUM CENTRAL PRESSURE...998 MB...29.47 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 800 PM PDT...0300 UTC...THE CENTER OF TROPICAL STORM SIMON WAS
LOCATED NEAR LATITUDE 18.1 NORTH...LONGITUDE 108.2 WEST. SIMON IS
MOVING TOWARD THE WEST NEAR 5 MPH...7 KM/H. THIS GENERAL MOTION
WITH A SLIGHT INCREASE IN FORWARD SPEED IS EXPECTED ON FRIDAY. A
TURN TOWARD THE WEST-NORTHWEST OR NORTHWEST IS ANTICIPATED ON
SATURDAY. ON THE FORECAST TRACK...THE CENTER OF SIMON SHOULD PASS
NEAR SOCORRO ISLAND LATE FRIDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 50 MPH...85 KM/H...WITH HIGHER
GUSTS. SIMON IS FORECAST TO BECOME A HURRICANE ON FRIDAY.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 45 MILES...75 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 998 MB...29.47 INCHES.


HAZARDS AFFECTING LAND
----------------------
RAINFALL...SIMON IS EXPECTED TO PRODUCE RAINFALL AMOUNTS OF 3 TO 5
INCHES WITH ISOLATED AMOUNTS AROUND 8 INCHES THROUGH FRIDAY ACROSS
WESTERN GUERRERO AND MICHOACAN...COLIMA...WESTERN JALISCO AND
NAYARIT IN WESTERN MEXICO. THESE RAINS COULD CAUSE FLASH FLOODING
AND MUD SLIDES.

SURF...SWELLS GENERATED BY SIMON ARE AFFECTING PORTIONS OF THE
SOUTHWESTERN COAST OF MEXICO. THESE SWELLS ARE LIKELY TO CAUSE
LIFE-THREATENING SURF AND RIP CURRENT CONDITIONS. PLEASE CONSULT
PRODUCTS FROM YOUR LOCAL WEATHER OFFICE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...200 AM PDT.

$$
FORECASTER AVILA


TROPICAL STORM SIMON DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL EP192014
800 PM PDT THU OCT 02 2014

A series of microwave overpasses during the past few hours
confirmed that Simon is a little south and east of previous
estimates, and that the cyclone is now moving westward or 270
degrees at 4 kt. Although the cloud pattern is gradually becoming
better organized with more symmetric convection and better-defined
outflow, Dvorak estimates from TAFB and SAB indicate that the winds
are still 45 kt. The CIMSS-ADT indicate that Simon could be a little
stronger.

Simon is forecast to move soon over a pool of even warmer water
and the shear is light. This should result in strengthening, and the
NHC forecast calls for Simon to become a hurricane in about 24
hours. In fact, rapid intensification is not out of the question
since the SHIPS-RI index has increased again tonight. After 3 days,
the circulation of the cyclone will begin to feel the influence of
cooler waters and a stable environment, and gradual weakening
should commence.

There is high confidence that Simon will gradually turn to the
northwest with an increase in forward speed during the next 3 days
while the cyclone is located on the southwestern side of the high
pressure system over Mexico. Most of the track guidance agree with
this scenario. After that time, the confidence in the track forecast
is quite low since the GFS together with its dependent models
recurve the cyclone toward the Baja California peninsula. On the
contrary, the ECMWF keeps Simon moving westward over open waters.
The NHC forecast is in the middle of these two extremes, and for now
keeps Simon drifting northward by the end of the forecast period.


FORECAST POSITIONS AND MAX WINDS

INIT 03/0300Z 18.1N 108.2W 45 KT 50 MPH
12H 03/1200Z 18.3N 109.8W 55 KT 65 MPH
24H 04/0000Z 18.9N 111.5W 65 KT 75 MPH
36H 04/1200Z 19.6N 113.3W 70 KT 80 MPH
48H 05/0000Z 20.7N 114.8W 75 KT 85 MPH
72H 06/0000Z 22.5N 115.6W 70 KT 80 MPH
96H 07/0000Z 24.0N 115.5W 60 KT 70 MPH
120H 08/0000Z 24.5N 115.5W 40 KT 45 MPH

$$
Forecaster Avila

[Yellow Evan]

Given the higher ADT, I would have went 50 knts.

NHC track still too far west for my liking.

[Yellow Evan]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.2.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 03 OCT 2014 Time : 014500 UTC
Lat : 18:24:03 N Lon : 108:37:21 W


CI# /Pressure/ Vmax
3.7 / 989.5mb/ 59.0kt


Final T# Adj T# Raw T#
3.7 3.8 3.9

Center Temp : -62.6C Cloud Region Temp : -64.9C

Scene Type : UNIFORM CDO CLOUD REGION

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : EAST PACIFIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : 0.7T/6hr
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 36km
- Environmental MSLP : 1010mb

Satellite Name : GOES13
Satellite Viewing Angle : 43.8 degrees

[Yellow Evan]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.2.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 03 OCT 2014 Time : 021500 UTC
Lat : 18:05:47 N Lon : 108:06:15 W


CI# /Pressure/ Vmax
3.8 / 988.3mb/ 61.0kt


Final T# Adj T# Raw T#
3.8 3.8 4.1

Center Temp : -75.5C Cloud Region Temp : -68.4C

Scene Type : UNIFORM CDO CLOUD REGION

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : EAST PACIFIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : 0.7T/6hr
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 36km
- Environmental MSLP : 1010mb

Satellite Name : GOES13
Satellite Viewing Angle : 43.1 degrees

[TropicalAnalystwx13]

There's a disconnect between Simon's satellite appearance and actual sustained winds, with the latest ASCAT pass only indicating a small area of 35kt winds. Even taking into consideration the small size of the storm, anything above 45kt is not justifiable, and 45kt might be pushing it. We'll see how things go overnight.

[cycloneye]

TROPICAL STORM SIMON DISCUSSION NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL EP192014
200 AM PDT FRI OCT 03 2014


Microwave satellite images early this morning indicate that the
inner-core region of Simon is not particularly well organized. A
low-level eye feature has been intermittent since about 0000 UTC,
but the most recent images do not show the eye feature any longer.
Subjective and objective satellite intensity estimates suggest that
Simon has strengthened to 55-60 kt based on a CDO feature. However,
two ASCAT overpasses at 0412 UTC and 0504 UTC only indicated surface
winds of 39 kt and 41 kt, respectively. Even allowing for some
undersampling due to the compact size of the cyclone likely only
yields 45-50 kt. Owing to the lack of persistent central features,
the initial intensity is being held at 45 kt for this advisory.

The initial motion is an uncertain 280/06 kt and is based primarily
on microwave satellite fixes. There remains high confidence that
Simon will continue to move westward to west-northwestward for the
next 2-3 days as the cyclone navigates around the western periphery
of a strong deep-layer ridge located north of the cyclone. After
that time, however, the model guidance diverges quite significantly.
The overwhelming majority of the guidance recurves Simon toward the
north by Day 4 and toward the northeast by Day 5. However, the very
reliable ECMWF model takes Simon farther west through Day 5 and
does not recurve the cyclone until after this forecast period.
Owing to the significant differences in the various model solutions,
and out of respect for the ECMWF model, and given that mid-level
northwesterly flow patterns are not conducive for recurvature
scenarios, the official forecast was only nudged a little to the
west of the previous forecast track.

Simon will be moving over warmer water with SSTs near 28-29C during
the next 24-36 hours while the deep-layer vertical shear is light.
However, modest easterly mid-level shear that has been undercutting
the otherwise impressive outflow pattern may continue to
occasionally disrupt the inner core convection before Simon reaches
cooler water and a drier, more stable airmass by Days 4 and 5. As
a result, only slow steady strengthening is forecast, which is
similar to the SHIPS intensity model and the previous forecast.

FORECAST POSITIONS AND MAX WINDS

INIT 03/0900Z 18.3N 108.9W 45 KT 50 MPH
12H 03/1800Z 18.7N 110.3W 55 KT 65 MPH
24H 04/0600Z 19.3N 112.2W 65 KT 75 MPH
36H 04/1800Z 20.0N 114.1W 75 KT 85 MPH
48H 05/0600Z 21.0N 115.8W 75 KT 85 MPH
72H 06/0600Z 22.5N 116.5W 60 KT 70 MPH
96H 07/0600Z 24.0N 116.0W 50 KT 60 MPH
120H 08/0600Z 25.0N 115.5W 35 KT 40 MPH

$$
Forecaster Stewart

[Yellow Evan]

Given the chance for the winds to catch up to the satellite presentation, I still would go with 50 knts.

Why is the NHC placing so much weight on the ECMWF?

[Yellow Evan]

Looks slightly sheared

20141003 1200 18.4 109.3 T3.0/3.5 19E SIMON

TXPZ27 KNES 031219
TCSENP

A. 19E (SIMON)

B. 03/1200Z

C. 18.4N

D. 109.3W

E. THREE/GOES-W

F. T3.0/3.5/D0.5/24HRS

G. IR/EIR/SWIR/AMSU

H. REMARKS...SYSTEM HAS NOT DEVELOPED AS MT=3.5 AND DT=3.0 BASED ON 7/10
BANDING. PAT=3.0. AND FT HAS WEAKENED 0.5 OVER 06HRS. FT IS BASED ON DT.

I. ADDL POSITIONS

03/0835Z 18.4N 108.9W AMSU


...SWANSON

ADT only supports 50 knts, but it supported 65 knts earlier.


UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.2.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 03 OCT 2014 Time : 111500 UTC
Lat : 18:23:21 N Lon : 109:15:30 W


CI# /Pressure/ Vmax
4.0 / 985.5mb/ 65.0kt


Final T# Adj T# Raw T#
3.2 3.2 3.1

Center Temp : -79.2C Cloud Region Temp : -57.1C

Scene Type : IRREGULAR CDO*

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : EAST PACIFIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : 0.7T/6hr
Weakening Flag : ON
Rapid Dissipation Flag : FLAG

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 25km
- Environmental MSLP : 1010mb

Satellite Name : GOES13
Satellite Viewing Angle : 44.4 degrees

[Yellow Evan]

A tad elongated now.

EP, 19, 2014100312, , BEST, 0, 184N, 1093W, 45, 998, TS, 34, NEQ, 40, 30, 20, 30, 1008, 150, 10, 0, 0, E, 0, , 0, 0, SIMON, D,

[cycloneye]

TROPICAL STORM SIMON DISCUSSION NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL EP192014
800 AM PDT FRI OCT 03 2014

First-light visible imagery and a 1205 UTC SSMI/S overpass indicate
that Simon has become a little better organized. The storm has a
central dense overcast with outer bands present in all quadrants,
and the microwave data shows a mid-level eyewall forming near or
over the low-level center. However, the cloud pattern continues
to show some signs of easterly shear. Satellite intensity
estimates are 55 kt from TAFB and SAB, and recent CIMSS ADT, AMSU,
and SATCON estimates are 50-55 kt. The initial intensity is thus
increased to 50 kt.

The initial motion is now 285/8. Simon should move generally
west-northwestward for the next 36 hours or so as it is steered by
the subtropical ridge to the north and northeast. After that time,
the track guidance becomes very divergent. The GFS, GFS ensemble
mean, and UKMET forecast Simon to recurve through a break in the
ridge near 115W and move inland over Baja California and
northwestern Mexico. The ECMWF and the NAVGEM show Simon moving much
farther west, with a northward turn delayed until the cyclone is
west of 120W. Given the magnitude of the disagreement, the official
forecast will follow the trend of the previous forecast in showing
a slow northward to northeastward motion from 72-120 hours. The new
forecast track is and update of the previous track and similar to,
but slower than, the Florida State Superensemble.

Simon will be moving over warmer water with SSTs near 28-29C during
the next 24-36 hours while the deep-layer vertical shear is
expected to be light. This should allow continued strengthening
until the cyclone encounters cooler waters in 36-48 hours. The new
intensity forecast is similar to the previous forecast and is in
best agreement with the SHIPS model. There are two major sources
of uncertainty in the intensity forecast. The first is that rapid
intensification is still a possibility during the next 24 hours or
so, although the probabilities shown in the SHIPS Rapid
Intensification Index are slowly decreasing. Second, how much cool
water Simon will encounter is dependent on the track. The GFS track
would keep the storm over relatively warm water, while the ECMWF/
NAVGEM track would take it over much cooler water.


FORECAST POSITIONS AND MAX WINDS

INIT 03/1500Z 18.6N 109.8W 50 KT 60 MPH
12H 04/0000Z 19.1N 111.4W 55 KT 65 MPH
24H 04/1200Z 19.6N 113.3W 65 KT 75 MPH
36H 05/0000Z 20.5N 115.0W 75 KT 85 MPH
48H 05/1200Z 21.5N 116.1W 75 KT 85 MPH
72H 06/1200Z 23.0N 116.5W 60 KT 70 MPH
96H 07/1200Z 24.5N 116.0W 50 KT 60 MPH
120H 08/1200Z 25.5N 115.0W 35 KT 40 MPH

$$
Forecaster Beven

[cycloneye]

18z Best Track up to 55kts.

EP, 19, 2014100318, , BEST, 0, 186N, 1101W, 55, 993, TS

[cycloneye]

BULLETIN
TROPICAL STORM SIMON ADVISORY NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL EP192014
200 PM PDT FRI OCT 03 2014

...SIMON STRENGTHENING AS IT APPROACHES SOCORRO ISLAND...


SUMMARY OF 200 PM PDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...18.8N 110.6W
ABOUT 25 MI...40 KM E OF SOCORRO ISLAND
ABOUT 285 MI...460 KM S OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...993 MB...29.33 INCHES



TROPICAL STORM SIMON DISCUSSION NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL EP192014
200 PM PDT FRI OCT 03 2014

Recent visible imagery shows that Simon is getting better
organized, with the inner core convection now wrapping around the
center. In addition, a recent TRMM overpass shows a well-defined
low-level circulation center, and a recent ASCAT overpass shows a
few vectors of 50-55 kt. Satellite intensity estimates from TAFB
and SAB are 55 kt, and that will be the initial intensity.

The initial motion is 285/8. Simon should move generally west-
northwestward for the next 24-36 hours as it is steered by
the subtropical ridge to the north and northeast. After that time,
the track guidance remains very divergent. The GFS, GFS ensemble
mean, and GFDL forecast Simon to recurve through a break in the
ridge near 116W-117W and move inland over the Baja California
peninsula and northwestern Mexico. The GFS has shifted somewhat
westward since the last advisory, but this did not change its
forecast scenario. The ECMWF, NAVGEM, and Canadian models show
Simon moving farther west, with a northward turn delayed until the
cyclone is near 120W. The ECMWF and Canadian subsequently show Simon
dissipating over water. Overall, the guidance envelope has shifted a
little to the west at 48-120 hours since the last advisory, and the
official forecast does as well. The new forecast lies between the
TVCE consensus and the Florida State Superensemble from 48-120
hours, but is notably slower than both of those models.

Simon will be moving over warmer water with SSTs near 28-29C while
the deep-layer vertical shear is expected to be light. This should
allow continued strengthening until the cyclone encounters cooler
waters in about 36 hours. The new intensity forecast has been
increased over the previous forecast from 12-96 hours based on
current trends and the latest SHIPS model guidance. There remain
two major sources of uncertainty in the intensity forecast. The
first is that rapid intensification could occur during the next 24
hours or so. Second, how much cool water Simon will encounter is
dependent on the track. The GFS/GFS Ensemble Mean/GFDL track would
keep the storm over relatively warm water, while the ECMWF/NAVGEM/
Canadian track would take it over much cooler water.

The ASCAT data shows that Simon remains a very small cyclone in
terms of size, with tropical-storm force winds extending no more
than 40 n mi from the center.


FORECAST POSITIONS AND MAX WINDS

INIT 03/2100Z 18.8N 110.6W 55 KT 65 MPH
12H 04/0600Z 19.2N 112.2W 65 KT 75 MPH
24H 04/1800Z 20.0N 114.3W 75 KT 85 MPH
36H 05/0600Z 20.9N 115.6W 80 KT 90 MPH
48H 05/1800Z 21.9N 116.4W 80 KT 90 MPH
72H 06/1800Z 23.5N 116.5W 65 KT 75 MPH
96H 07/1800Z 24.5N 116.0W 50 KT 60 MPH
120H 08/1800Z 25.5N 115.5W 35 KT 40 MPH

$$
Forecaster Beven

[wxman57]

I'm seeing an eye peeking through on satellite imagery. May be a hurricane now.