EPAC: PAMELA - Remnants

[Sciencerocks]

[aspen]

Yeah this isn’t going to RI. It remains sheared and does not have enough time to build a core before the start of its recurve. Higher-than-expected shear once again becomes a factor.

[Kingarabian]

Shear induced cold tops it looks like to me. Almost a CCC.

[Yellow Evan]

Yeah this isn’t going to RI. It remains sheared and does not have enough time to build a core before the start of its recurve. Higher-than-expected shear once again becomes a factor.

This has 48 hours to deepen. It’s been slowly trying to rotate convection upshear which is a sign shear is not increasing. It’s also not hard to envision a 24 hour period where the storm deepens from say 65 to 125 knots given the trough interaction. Pamela is still on track for now IMO though if there are no signs of an inner core by 18z-0z, then the clock is ticking and we can have a real conversation about this busting but anyone who tracked 2014-18 EPAC should know not to count your chickens before they hatch. Shear hasn’t even been higher than expected - none of the GFS runs really deepened this until it’s northerly turn started.

[aspen]

I’m guessing the HWRF is being too progressive with EWRCs, always trying to start one within 12-24 hours of Pamela going pinhole no matter how much the pinhole phase is delayed. I did compliment it on guessing Larry’s massive eye, but it showed the EWRC that caused it happening too soon, and this could be the same case here. A pinhole through landfall would confine the area of worst impacts to a much smaller space, and make Pamela more vulnerable to last-minute disruption like Delta.

[skyline385]

Yeah this isn’t going to RI. It remains sheared and does not have enough time to build a core before the start of its recurve. Higher-than-expected shear once again becomes a factor.

Raw T up to 4.6 and the CDO doesn't look that sheared anymore. The V shape seems to be gone with the latest burst through the center.

[tolakram]

COD IR loop

https://weather.cod.edu/satrad/?parms=meso-meso1-13-200-1-100-1&checked=map&colorbar=undefined

[aspen]

Oh wow. A core is already developing. That was quick, seeing how Pamela’s LLC was exposed just 3 hours before this pass.


12z BT is up to 55kt/995mb

[zzh]

[abajan]

Tropical Storm Pamela Advisory Number 6
NWS National Hurricane Center Miami FL EP162021
900 AM MDT Mon Oct 11 2021

...PAMELA RAPIDLY STRENGTHENING...
...HURRICANE AND TROPICAL STORM WATCHES ISSUED FOR PORTIONS OF
SOUTHWESTERN MEXICO AND SOUTHERN BAJA CALIFORNIA SUR...


SUMMARY OF 900 AM MDT...1500 UTC...INFORMATION
----------------------------------------------
LOCATION...16.8N 108.1W
ABOUT 455 MI...735 KM SSW OF MAZATLAN MEXICO
ABOUT 435 MI...705 KM SSE OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...NW OR 320 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...995 MB...29.39 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

The government of Mexico has issued a Hurricane Watch for portions
of the southwestern coast of Mexico from Bahia Tempehuaya southward
to Escuinapa.

A Tropical Storm Watch has been issued from Bahia Tempehuaya
northward to Altata, and also from Escuinapa southward to San Blas,
including all the Isla Marias archipelago.

A Tropical Storm Watch has also been issued for extreme southern
Baja California Sur from Los Barilles southward to Cabo San Lucas.

[cycloneye]

Tropical Storm Pamela Discussion Number 6...Corrected
NWS National Hurricane Center Miami FL EP162021
900 AM MDT Mon Oct 11 2021

Corrected to update Key Messages

Pamela's convective pattern has undergone a pronounced bursting
phase since the previous advisory, including significant lightning
activity in the inner-core region near the center, with formation
of a Central Dense Overcast (CDO) now evident. However, the
lightning ceased about 5 h ago and the CDO has recently become a
little disheveled looking along with pronounced warming of the
cloud tops compared to the much colder cloud tops colder than -85C
just a few hours ago. The advisory intensity has been increased to
55 kt based on an average of satellite intensity estimates of
T4.0/65 from TAFB, T3.0/45 kt from SAB, and T3.5/55 kt from
UW-CIMSS ADT.

Pamela has slowed down significantly since the previous advisory,
and the motion estimate is now northwestward or 320/07 kt. A
northwestward motion should continue today as Pamela approaches an
east-to-west-oriented subtropical ridge axis situated along 19-20N
latitude. By late tonight, the storm is forecast to turn slowly
northward, followed by a motion toward the northeast at a faster
forward speed by Tuesday night. As Pamela gets caught up in the
moderate southwesterly flow between the subtropical ridge to its
south and an approaching mid-latitude trough to the northwest, the
cyclone should continue to accelerate northeastward on Wednesday
until Pamela makes landfall along the southwest coast of Mexico. The
new NHC forecast track is a tad to the right of and slightly faster
than the previous advisory track, and close to the middle of the
tightly packed simple- and corrected-consensus track model envelope.

The recent disruption in Pamela's convective pattern has likely
been due the cyclone having entrained a slug of dry air. However,
this convective hiatus will likely be short-lived due to the robust
inner-core wind field noted in earlier ASCAT wind data, which should
allow for Pamela to mix out any dry air. Moderate northerly shear is
forecast to subside over the next 24 hours, giving way to the
development of an upper-level anticyclone over the storm, along
with an impressive outflow pattern developing in the northern
semicircle. The combination of a tight inner-core wind field, low
vertical shear, very warm sea-surface temperatures, and a moist
mid-level environment should allow for Pamela to rapid intensify
for the next 36 hours -- possibly even right up until Pamela
reaches the coast of Mexico. The latest official intensity
forecast is very similar to the previous advisory, and is an average
of the consensus intensity models IVCN and NOAA-HCCA, an remains
at the high end of the intensity guidance. Pamela is expected to
become a dangerous major hurricane prior to landfall. After inland
occurs, rapid weakening is expected as the storm moves over the
rugged terrain of west-central Mexico. However, higher elevations
could still receive tropical-storm force winds after Pamela moves
well inland.

An Air Force Reserve Hurricane Hunter aircraft is scheduled to
investigate Pamela Tuesday late morning and early afternoon.


Key Messages:

1. Pamela is forecast to be a major hurricane when it reaches the
coast of west-central mainland Mexico on Wednesday, and
life-threatening storm surge and dangerous hurricane-force winds are
possible within the Hurricane Watch area. Residents in this area
should monitor the progress of Pamela and follow any advice given by
local officials.

2. Pamela is expected to pass near or south of the southern tip of
the Baja California peninsula as a hurricane Tuesday night and early
Wednesday, and tropical-storm conditions are possible within the
Tropical storm Watch area.

3. Heavy rains associated with Pamela are expected to move into the
Mexican States of Sinaloa and western Durgano along with southern
portions of Baja California Sur Tuesday and Wednesday. This will
pose a threat of significant and life-threatening flash flooding and
mudslides.


FORECAST POSITIONS AND MAX WINDS

INIT 11/1500Z 16.8N 108.1W 55 KT 65 MPH
12H 12/0000Z 17.8N 108.9W 70 KT 80 MPH
24H 12/1200Z 19.3N 109.3W 85 KT 100 MPH
36H 13/0000Z 21.1N 108.8W 100 KT 115 MPH
48H 13/1200Z 23.3N 107.1W 105 KT 120 MPH
60H 14/0000Z 25.7N 104.9W 35 KT 40 MPH...INLAND
72H 14/1200Z 29.1N 100.8W 25 KT 30 MPH...POST-TROP/INLAND
96H 15/1200Z...DISSIPATED

$$
Forecaster Stewart

[aspen]

Pamela will likely spend all of today organizing its core and attempt further intensification late tonight or tomorrow, meaning that recon will be arriving at a pretty good time to sample the storm. Hopefully its peak doesn’t fall between fixes.

[Yellow Evan]

 https://twitter.com/cyclonicwx/status/1447572338833244174

[aspen]

It definitely seems that some dry air got into Pamela’s core and will delay intensification until it mixes out. Also, even the NHC is saying that Pamela could RI into landfall, so it would appear the post-recurve trough interaction won’t impart significant shear like I thought.

[Sciencerocks]

[Yellow Evan]

Much better compared to yesterday. Curved bands have increased and there’s actual outflow out of the north now. Convection still struggling to rotate upshear, however.

[Yellow Evan]

12z GFS has significant intensification today now.

[aspen]

The LLC is becoming exposed again. I think we can toss out the 12z HWRF as a result; Pamela is not organized enough to undergo the RI this run shows. Shear and dry air appear to be just a little too much.

[cycloneye]

BULLETIN
Tropical Storm Pamela Intermediate Advisory Number 6A
NWS National Hurricane Center Miami FL EP162021
1200 PM MDT Mon Oct 11 2021

...PAMELA CONTINUES TO STRENGTHEN...
...EXPECTED TO BECOME A HURRICANE TONIGHT AND A MAJOR HURRICANE ON
TUESDAY...


SUMMARY OF 1200 PM MDT...1800 UTC...INFORMATION
-----------------------------------------------
LOCATION...16.8N 108.2W
ABOUT 455 MI...735 KM SSW OF MAZATLAN MEXICO
ABOUT 435 MI...700 KM SSE OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...NW OR 320 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...992 MB...29.29 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Hurricane Watch is in effect for...
* Bahia Tempehuaya to Escuinapa

A Tropical Storm Watch is in effect for...
* North of Bahia Tempehuaya to Altata
* South of Escuinapa to San Blas
* Isla Marias
* Los Barilles to Cabo San Lucas

A Hurricane Warning and a Tropical Storm Warning will likely be
required tonight for portions of the current Watch areas by this
afternoon or evening.

For storm information specific to your area, please monitor
products issued by your national meteorological service.


DISCUSSION AND OUTLOOK
----------------------
At 1200 PM MDT (1800 UTC), the center of Tropical Storm Pamela was
located near latitude 16.8 North, longitude 108.2 West. Pamela is
moving toward the northwest near 6 mph (9 km/h), and this general
motion is expected to continue today. A turn toward the north is
forecast to occur tonight into Tuesday, followed by a faster
northeastward motion by Tuesday night. On the forecast track,
Pamela will pass south of the southern tip of the Baja California
peninsula Tuesday night or early Wednesday and make landfall on
west-central mainland Mexico Wednesday morning.

Maximum sustained winds have increased to near 70 mph (110 km/h)
with higher gusts. Steady to rapid strengthening is forecast, and
Pamela is expected to become a hurricane by tonight and a major
hurricane on Tuesday. Pamela is forecast remain a major hurricane
until it reaches the coast of Mexico on Wednesday.

Tropical-storm-force winds extend outward up to 70 miles (110 km)
from the center.

The estimated minimum central pressure is 992 mb (29.29 inches).


HAZARDS AFFECTING LAND
----------------------
WIND: Hurricane conditions are possible within the Hurricane Watch
area by late Tuesday, with tropical storm conditions possible by
Tuesday afternoon. Tropical storm conditions are possible within the
Tropical Storm Watch areas by Tuesday afternoon.

RAINFALL: Pamela is expected to produce the following rainfall
amounts through Wednesday:

Across the Mexican States of Sinaloa and western Durango... 4 to 8
inches with isolated maximum totals of 12 inches. This rainfall may
trigger significant and life-threatening flash flooding and
mudslides.

Across southern portions of Baja California Sur... 2 to 4 inches
with isolated maximum totals of 6 inches.

SURF: Pamela is expected to generate swells that will affect
portions of the southern Baja California peninsula and southwestern
and west-central mainland Mexico by late Tuesday. 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 at 300 PM MDT.

$$
Forecaster Stewart

[Yellow Evan]

TXPZ29 KNES 111751
TCSENP

A. 16E (PAMELA)

B. 11/1730Z

C. 16.4N

D. 108.2W

E. THREE/GOES-E

F. T3.0/3.0

G. IR/EIR/VIS

H. REMARKS...7.5/10 BANDING AROUND THE LLCC YIELDS A DT OF 3.0. MET
AND PT AGREE AND ARE BOTH EQUAL TO 3.0 BASED ON A DEVELOPMENT TREND IN
THE LAST 24 HOURS. FT IS BASED ON DT.

I. ADDL POSITIONS

NIL


...TUGGLE