EPAC: NORMA - Remnants - Discussion

[cycloneye]

BULLETIN
Tropical Storm Norma Advisory Number 1
NWS National Hurricane Center Miami FL EP172023
300 PM MDT Tue Oct 17 2023

...TROPICAL STORM NORMA DEVELOPS IN THE EASTERN PACIFIC...


SUMMARY OF 300 PM MDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...13.2N 107.3W
ABOUT 445 MI...720 KM SSW OF MANZANILLO MEXICO
ABOUT 690 MI...1110 KM SSE OF CABO SAN LUCAS MEXICO
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES


TCDEP2

Tropical Storm Norma Discussion Number 1
NWS National Hurricane Center Miami FL EP172023
300 PM MDT Tue Oct 17 2023

Satellite imagery this afternoon depicts that the area the National
Hurricane Center has been monitoring offshore of the southwestern
coast of Mexico (EP90) has become better organized. Showers and
thunderstorms have been consolidating, with curved band features
developing around a recently well-defined low-level center.
Subjective Dvorak satellite intensity estimates are T2.5/T3.0 from
TAFB and SAB, respectively. Given the improved satellite
presentation and these intensity estimates, advisories are being
initiated on Tropical Storm Norma with an initial intensity of 35
kt.

Norma is in a fairly conducive environment for intensification. Low
vertical wind shear, warm sea surface temperatures, and favorable
upper-level diffluence will likely lead to steady to rapid
strengthening for the next few days. DTOPS and SHIPS rapid
intensification (RI) indices are between 60 to 70 percent for a 55
kt increase over the next 48 hours, and the NHC forecast is near
that value, explicitly forecasting RI between 12 to 36 hours.
Towards the end of the forecast, increasing vertical wind shear and
potential drier air intrusions could cause the system to gradually
weaken. The NHC forecast lies just below the HCCA HFIP corrected
consensus aids, and it is noted that the HAFS-A/B hurricane regional
models show a higher, but still plausible, peak intensity.

Norma is moving west-northwestward at an estimated motion of 285/9
kt. The system is expected to turn more northwestward at a slightly
slower forward speed during the next few days around the western
periphery of a mid-level ridge. Towards the end of the forecast
period as the system moves toward the Baja peninsula, there is a
notable divergence among the model suite. A stronger vortex, as
depicted in the GFS/CMC model, would be picked up by an approaching
trough from the northwest and move the system northeastward towards
the Baja peninsula. However, a weaker vortex would tend to meander
south of the peninsula and be missed by the approaching trough,
like the ECMWF/UKMET solutions. Since the NHC intensity forecast
is on the strong side of the guidance, the official track is closer
to the right side of the guidance envelope, more similar to the GFS
and HCCA models.


FORECAST POSITIONS AND MAX WINDS

INIT 17/2100Z 13.2N 107.3W 35 KT 40 MPH
12H 18/0600Z 13.8N 108.0W 45 KT 50 MPH
24H 18/1800Z 15.0N 108.4W 60 KT 70 MPH
36H 19/0600Z 16.0N 108.6W 75 KT 85 MPH
48H 19/1800Z 16.9N 108.8W 85 KT 100 MPH
60H 20/0600Z 17.8N 109.1W 95 KT 110 MPH
72H 20/1800Z 18.7N 109.6W 95 KT 110 MPH
96H 21/1800Z 20.9N 110.3W 90 KT 105 MPH
120H 22/1800Z 22.5N 110.0W 85 KT 100 MPH

$$
Forecaster Kelly

[Yellow Evan]

EP, 17, 2023101800, , BEST, 0, 134N, 1076W, 45, 1000, TS, 34, NEQ, 120, 30, 0, 120, 1007, 180, 40, 0, 0, E, 0, , 0, 0, NORMA, M, 0, , 0, 0, 0, 0, genesis-num, 028,

[Yellow Evan]

TXPZ25 KNES 180023
TCSENP

A. NORMA (90E)

B. 18/0000Z

C. 13.3N

D. 107.7W

E. THREE/GOES-W

F. T3.0/3.0

G. IR/EIR/VIS

H. REMARKS...6/10 BANDING RESULTED IN A DT OF 3.0. MET IS 2.5 AND PT
IS 3.0. THE FT IS BASED ON THE DT.

I. ADDL POSITIONS

NIL


...ZHU

[Sciencerocks]

[cycloneye]

Josh planning to chase Norma.

 https://twitter.com/iCyclone/status/1714409447093604491

[Yellow Evan]

Convection rotating downshear. Likely less than 12 hours away from hurricane status given microwave has a low-level inner core.

[cycloneye]

BULLETIN
Tropical Storm Norma Advisory Number 2
NWS National Hurricane Center Miami FL EP172023
900 PM MDT Tue Oct 17 2023

...NORMA STRENGTHENING...


SUMMARY OF 900 PM MDT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...13.7N 107.8W
ABOUT 435 MI...695 KM SSW OF MANZANILLO MEXICO
ABOUT 650 MI...1045 KM SSE OF CABO SAN LUCAS MEXICO
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES



Tropical Storm Norma Discussion Number 2
NWS National Hurricane Center Miami FL EP172023
900 PM MDT Tue Oct 17 2023

Norma is becoming better organized on satellite imagery. There is
a developing Central Dense Overcast with very cold cloud tops, and
some convective banding is evident. Upper-level outflow is fairly
well defined over the western semicircle of the circulation. The
current intensity estimate is set at 45 kt in agreement with the
latest Dvorak classifications from TAFB and SAB.

Based on recent center fixes, the motion is now northwestward, or
around 305/7 kt. A weak mid-level ridge to the east of Norma
should maintain a slow northwestward to north-northwestward track
for the next 48 to 72 hours. Later in the forecast period, there is
significant uncertainty in the track, since the model guidance at 3
to 5 days is not in very good agreement. The ECMWF and UKMET show a
weakening cyclone moving along the western side of the guidance
envelope whereas the GFS show a strong system moving much more to
the northeast. The 4- and 5-day official forecast positions
are close to the simple and corrected model consensus predictions.
However there is low confidence in this forecast, given the spread
in the model tracks.

For the next couple of days, the storm should be in an atmospheric
and oceanic environment that will be quite conducive for
strengthening. The SHIPS Rapid Intensification (RI) indices and
the DTOPS probabilities for RI suggest a high likelihood for
significant strengthening during the next 48 hours or so. This is
also reflected in the NHC intensity forecast, which explicitly
shows RI in the earlier part of the period. In 3 to 5 days, higher
south-southwesterly vertical wind shear and drier air is likely to
inhibit strengthening. The official forecast is near or above the
intensity model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT 18/0300Z 13.7N 107.8W 45 KT 50 MPH
12H 18/1200Z 14.4N 108.2W 55 KT 65 MPH
24H 19/0000Z 15.5N 108.5W 70 KT 80 MPH
36H 19/1200Z 16.5N 108.6W 85 KT 100 MPH
48H 20/0000Z 17.3N 108.8W 90 KT 105 MPH
60H 20/1200Z 18.2N 109.2W 95 KT 110 MPH
72H 21/0000Z 19.2N 109.6W 95 KT 110 MPH
96H 22/0000Z 21.3N 110.2W 90 KT 105 MPH
120H 23/0000Z 22.5N 109.8W 85 KT 100 MPH

$$
Forecaster Pasch

[Kingarabian]

Euro remains very bearish with this.

[Extratropical94]

EP, 17, 2023101806, , BEST, 0, 139N, 1078W, 55, 995, TS

[cycloneye]

BULLETIN
Tropical Storm Norma Advisory Number 3
NWS National Hurricane Center Miami FL EP172023
300 AM MDT Wed Oct 18 2023

...NORMA CONTINUING TO STRENGTHEN...


SUMMARY OF 300 AM MDT...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...14.2N 107.9W
ABOUT 410 MI...655 KM SW OF MANZANILLO MEXICO
ABOUT 615 MI...990 KM SSE OF CABO SAN LUCAS MEXICO
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...NW OR 320 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...995 MB...29.39 INCHES



Tropical Storm Norma Discussion Number 3
NWS National Hurricane Center Miami FL EP172023
300 AM MDT Wed Oct 18 2023

Satellite imagery shows Norma quickly becoming better organized. The
Central Dense Overcast is continuing to expand, with cold cloud top
temperatures of less than -90 degrees C. A recent ASCAT pass over
the eastern edge of the storm suggested that the low-level center
was near the southeastern side of the deepest convection. The
initial intensity is set at 55 kt, in agreement with the latest
subjective and objective Dvorak classifications from TAFB and
UW-CIMSS ADT, respectively.

Norma appears to be gradually turning, and the latest motion is
estimated to be 320/6 kt. A weak ridge over Mexico is expected to
steer the storm north-northwestward to northward for about 3 days.
There is still significant uncertainty in the track prediction later
in the forecast period, which is likely related to the anticipated
vortex depth. Global models that show a weaker cyclone, such as the
ECMWF, turn the system westward prior to the Baja California
peninsula. Model guidance with a stronger, deeper circulation tend
to bring the storm farther north and turn it eastward by the end of
the forecast period. The updated official track forecast is very
similar to the previous prediction and is close to the simple model
consensus aid, TVCE. However, there is low confidence in this
forecast given the spread in the model tracks.

Environmental and oceanic conditions are likely to remain conducive
for additional strengthening through the next day or so.
Statistical indices predicting the probability of rapid
intensification, such as SHIPS-RI and DTOPS, suggest a very high
likelihood of rapid strengthening within 24 hours. The latest NHC
intensity forecast explicitly shows rapid intensification, with a
peak of 100 kt by 36 h. By day 2, global model guidance shows that
the deep-layer vertical wind shear should increase over the storm
and likely induce a gradual weakening trend through the remainder of
the forecast period. The official forecast remains near or above
the intensity model consensus aids.


FORECAST POSITIONS AND MAX WINDS

INIT 18/0900Z 14.2N 107.9W 55 KT 65 MPH
12H 18/1800Z 15.0N 108.1W 70 KT 80 MPH
24H 19/0600Z 16.2N 108.3W 85 KT 100 MPH
36H 19/1800Z 17.0N 108.5W 100 KT 115 MPH
48H 20/0600Z 17.9N 108.9W 95 KT 110 MPH
60H 20/1800Z 18.9N 109.4W 90 KT 105 MPH
72H 21/0600Z 20.0N 109.8W 85 KT 100 MPH
96H 22/0600Z 22.1N 110.1W 80 KT 90 MPH
120H 23/0600Z 22.9N 109.4W 75 KT 85 MPH

$$
Forecaster Bucci

[DorkyMcDorkface]

[Sciencerocks]

[ElectricStorm]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 9.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 18 OCT 2023 Time : 144020 UTC
Lat : 14:45:55 N Lon : 107:53:49 W


CI# /Pressure/ Vmax
4.0 / 986.2mb/ 65.0kt


Final T# Adj T# Raw T#
4.0 4.2 4.2

Center Temp : -79.5C Cloud Region Temp : -77.2C

Scene Type : UNIFORM CDO CLOUD REGION

[underthwx]

How many cyclones have affected the Baja peninsula so far this season? Seems like it's been busy in that region thus far

[Yellow Evan]

Rotating quickly - needs to cut off the dry air intrusion.



6z ECMWF shows southerly shear kicking in as soon as tonight. I wouldn’t bet on this reaching major hurricane strength like the hurricane models and NHC show.

[Yellow Evan]

Tropical Storm Norma Discussion Number 4
NWS National Hurricane Center Miami FL EP172023
900 AM MDT Wed Oct 18 2023

The satellite presentation of Norma this morning suggests the storm
is strengthening. Deep convection appears to be consolidating near
and over the estimated center of the tropical cyclone. A large
curved band of convection wraps around the eastern portion of its
circulation. The latest objective and subjective satellite estimates
range from 55-63 kt, and the initial intensity is raised to 60 kt
for this advisory. Scatterometer overpasses are expected later
today, which will help assess the structure and extent of Norma's
wind field.

In the near term, the atmospheric and oceanic conditions appear
favorable for continued strengthening. Norma is moving over very
warm (>29C) waters, within a moist and very diffluent upper-level
environment. With only weak to moderate deep-layer southerly shear
expected during the next 12-24 h, Norma should become a hurricane
soon. The statistical rapid intensification (RI) indices indicate RI
is more likely than not during the next 24 h, and the NHC intensity
forecast continues to explicitly show RI with Norma peaking as a
major hurricane in 24-36 h. Then, an increase in southwesterly shear
by this weekend should induce weakening through the rest of the
forecast period. The NHC intensity prediction was lowered at days
4-5 based on the increasingly hostile conditions depicted in the
latest guidance.

Norma is moving north-northwestward (340/6 kt). This general motion
should continue for the next couple of days while the storm moves
around a weak ridge to its east. There is greater than normal
uncertainty in the track forecast beyond 48-60 h, with diverging
solutions among the various track models. Stronger models with a
deeper vortex, including the GFS and regional hurricane models, show
Norma turning northward to northeastward and passing near the
southern tip of Baja California before approaching mainland Mexico.
Some weaker solutions, such as the ECMWF and UKMET, suggest Norma
could meander offshore of Baja California within weak steering
currents or even turn southwestward away from land later in the
period. Given this large spread in the guidance, it seems prudent to
avoid making major track forecast changes this morning. Therefore,
the longer range NHC forecast is similar to the previous one, but
shows little net motion at days 4-5. Future advisories could
require more significant adjustments to the track forecast.


Key Messages:

1. Norma is forecast to become a hurricane later today and continue
strengthening through Thursday while it passes well offshore of
southwestern Mexico.

2. There is greater than normal uncertainty in the track and
intensity forecasts for Norma later this week and this weekend while
it approaches the Baja California peninsula. Regardless, Norma could
bring wind and rainfall impacts to southern portions of Baja
California Sur by Saturday, and interests there should monitor the
latest forecast updates.


FORECAST POSITIONS AND MAX WINDS

INIT 18/1500Z 14.8N 107.9W 60 KT 70 MPH
12H 19/0000Z 15.8N 108.1W 75 KT 85 MPH
24H 19/1200Z 16.9N 108.3W 90 KT 105 MPH
36H 20/0000Z 17.8N 108.5W 100 KT 115 MPH
48H 20/1200Z 18.7N 109.0W 90 KT 105 MPH
60H 21/0000Z 19.6N 109.5W 85 KT 100 MPH
72H 21/1200Z 20.8N 109.9W 75 KT 85 MPH
96H 22/1200Z 21.9N 109.9W 65 KT 75 MPH
120H 23/1200Z 22.5N 109.5W 55 KT 65 MPH

$$
Forecaster Reinhart

[Yellow Evan]

TXPZ25 KNES 181824
TCSENP

A. 17E (NORMA)

B. 18/1800Z

C. 15.3N

D. 107.9W

E. THREE/GOES-W

F. T4.0/4.0

G. IR/EIR/VIS

H. REMARKS...11/10 BANDING YIELDS A DT OF 4.0. THE MET AND PT ARE ALSO
4.0. THE FT IS BASED ON THE DT.

I. ADDL POSITIONS

NIL


...GATLING

[Yellow Evan]

EP, 17, 2023101818, , BEST, 0, 153N, 1079W, 70, 984, HU, 34, NEQ, 120, 100, 60, 100, 1009, 240, 20, 0, 0, E, 0, , 0, 0, NORMA, D, 0, , 0, 0, 0, 0, genesis-num, 028,

[Sciencerocks]

[Iceresistance]

I have no idea why the RAW ADT came in at a 6.8 earlier, it is back down to a more reasonable 4.3.