ATL: ANA - Advisories

[Nancy Smar]

WTNT31 KNHC 220831
TCPAT1

BULLETIN
Subtropical Storm Ana Advisory Number 1
NWS National Hurricane Center Miami FL AL012021
500 AM AST Sat May 22 2021

...SUBTROPICAL STORM ANA FORMS JUST NORTHEAST OF BERMUDA...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...34.2N 62.2W
ABOUT 200 MI...320 KM NE OF BERMUDA
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...WSW OR 240 DEGREES AT 3 MPH...6 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES


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

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Watch is in effect for...
* Bermuda

A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, in this case within 24 hours.

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


DISCUSSION AND OUTLOOK
----------------------
At 500 AM AST (0900 UTC), the center of Subtropical Storm Ana was
located near latitude 34.2 North, longitude 62.2 West. The storm is
moving toward the west-southwest near 3 mph (6 km/h). A continued
slow and erratic motion is expected through tonight, followed by a
faster northeastward motion on Sunday and Monday.

Maximum sustained winds are near 45 mph (75 km/h) with higher gusts.
Little change in strength is forecast today, but gradual weakening
is expected tonight and Sunday. Ana is expected to dissipate in a
couple of days.

Winds of 40 mph extend outward up to 205 miles (335 km) north of the
center.

The estimated minimum central pressure is 1006 mb (29.71 inches).


HAZARDS AFFECTING LAND
----------------------
WIND: Tropical storm conditions are possible on Bermuda today.


NEXT ADVISORY
-------------
Next intermediate advisory at 800 AM AST.
Next complete advisory at 1100 AM AST.

$$
Forecaster Cangialosi

WTNT41 KNHC 220832
TCDAT1

Subtropical Storm Ana Discussion Number 1
NWS National Hurricane Center Miami FL AL012021
500 AM AST Sat May 22 2021

Satellite images indicate that the low pressure system that is
located a couple of hundred miles northeast of Bermuda has become
better organized overnight. The low now has a well-defined center
of circulation, some central deep convection, and thunderstorms that
are organized in curved bands to the north and northeast of the
center. The system is considered a subtropical cyclone rather than
a tropical cyclone since it is still entangled with an upper-level
low as evident in water vapor satellite images, but it does have
some tropical characteristics as well. The initial intensity is
estimated to be 40 kt, which makes the system Subtropical Storm Ana.

Ana is moving slowly to the west-southwest with the initial motion
estimated to be 240/3 kt. An even slower motion is expected later
this morning, and Ana is forecast to meander through tonight while
it remains embedded within the upper-level low in weak steering
currents. However, a mid- to upper-level trough moving off of
Atlantic Canada should cause Ana to turn northeastward thereafter
and accelerate in that direction on Sunday and Monday. The NHC
track forecast lies close to the HCCA and TVCA consensus models.

Ana will likely change little in strength in the short term, but a
combination of increasing shear, dry air, and decreasing SSTs should
cause the storm to gradually weaken tonight and Sunday. Nearly all
of the models show Ana opening up into a trough of low pressure in
about 48 to 60 hours, and so does the NHC forecast. The remnant
trough will likely be absorbed by a front shortly thereafter.

The Bermuda Weather Service has a Tropical Storm Watch in effect
for the island of Bermuda.


FORECAST POSITIONS AND MAX WINDS

INIT 22/0900Z 34.2N 62.2W 40 KT 45 MPH
12H 22/1800Z 34.3N 62.6W 40 KT 45 MPH
24H 23/0600Z 35.1N 61.9W 35 KT 40 MPH
36H 23/1800Z 36.2N 59.6W 35 KT 40 MPH
48H 24/0600Z 37.9N 55.4W 35 KT 40 MPH
60H 24/1800Z...DISSIPATED

$$
Forecaster Cangialosi

[cycloneye]

BULLETIN
Subtropical Storm Ana Intermediate Advisory Number 1A
NWS National Hurricane Center Miami FL AL012021
800 AM AST Sat May 22 2021

...ANA MOVING SLOWLY WHILE CENTERED NORTHEAST OF BERMUDA...


SUMMARY OF 800 AM AST...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...34.2N 62.5W
ABOUT 180 MI...290 KM NE OF BERMUDA
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...WSW OR 245 DEGREES AT 3 MPH...6 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES


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

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Watch is in effect for...
* Bermuda

A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, in this case within 24 hours.

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


DISCUSSION AND OUTLOOK
----------------------
At 800 AM AST (1200 UTC), the center of Subtropical Storm Ana was
located near latitude 34.2 North, longitude 62.5 West. The storm is
moving toward the west-southwest near 3 mph (6 km/h). A continued
slow and erratic motion is expected through tonight, followed by a
faster northeastward motion on Sunday and Monday.

Maximum sustained winds are near 45 mph (75 km/h) with higher
gusts. Little change in strength is forecast today, but gradual
weakening is expected tonight and Sunday. Ana is expected to
dissipate in a couple of days.

Winds of 40 mph extend outward up to 205 miles (335 km) north of
the center.

The estimated minimum central pressure is 1006 mb (29.71 inches).


HAZARDS AFFECTING LAND
----------------------
WIND: Tropical storm conditions are possible on Bermuda today.


NEXT ADVISORY
-------------
Next complete advisory at 1100 AM AST.

$$
Forecaster Beven

[cycloneye]

BULLETIN
Subtropical Storm Ana Advisory Number 2
NWS National Hurricane Center Miami FL AL012021
1100 AM AST Sat May 22 2021

...ANA NOW MOVING WESTWARD WHILE NORTHEAST OF BERMUDA...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...34.3N 63.0W
ABOUT 175 MI...280 KM NE OF BERMUDA
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 3 MPH...6 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES


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

The Bermuda Weather Service has discontinued the Tropical Storm
Watch for Bermuda.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

There are no coastal watches of warnings in effect.


DISCUSSION AND OUTLOOK
----------------------
At 1100 AM AST (1500 UTC), the center of Subtropical Storm Ana was
located near latitude 34.3 North, longitude 63.0 West. The storm is
moving toward the west near 3 mph (6 km/h). A turn toward the
north at a slow forward speed is expected later today, followed by
a faster motion toward the northeast Sunday and Monday.

Maximum sustained winds are near 45 mph (75 km/h) with higher gusts.
Little change in strength is forecast today, but gradual
weakening is expected tonight and Sunday. Ana is expected to
dissipate in a couple of days.

Winds of 40 mph extend outward up to 105 miles (165 km) mainly to
the north of the center.

The estimated minimum central pressure is 1006 mb (29.71 inches).


HAZARDS AFFECTING LAND
----------------------
WIND: Locally gusty winds are possible on Bermuda today.


NEXT ADVISORY
-------------
Next complete advisory at 500 PM AST.

$$
Forecaster Beven



Subtropical Storm Ana Discussion Number 2
NWS National Hurricane Center Miami FL AL012021
1100 AM AST Sat May 22 2021

Satellite imagery and radar data from Bermuda indicate that the
central convection associated with Ana has changed little in
organization during the past several hours, with a complex of small
bands near the center at this time. The initial intensity will be
held at 40 kt based on the latest intensity estimate from TAFB,
although recently-received ASCAT data suggests this could be a
little generous. Although the cyclone has some characteristics of
a tropical cyclone, Ana remains a subtropical storm based on its
position near the center of a large upper-level low pressure system
and the current lack of anticyclonic upper-level outflow.

The initial motion is 270/3. Ana and the large low it is embedded
in are expected to turn northward later today as a developing
mid-latitude cyclone over eastern Canada and the New England
states erodes the subtropical ridge west of Ana. After that, the
storm is expected to turn northeastward on the southeast side of
the mid-latitude cyclone. The track guidance is in good agreement
with this scenario, and the new track forecast is similar to, but a
little slower than, the various consensus models.

Little change in strength is expected for the next 12 h or so.
After Ana recurves, a combination of increasing shear, dry air, and
decreasing SSTs should cause the storm to gradually weaken tonight
and Sunday. The large-scale models agree upon Ana opening up into
a trough of low pressure in 36-48 h, and the official forecast
shows this happening just after 48 h. The remnant trough will
likely be absorbed by a cold front associated with the mid-latitude
cyclone shortly thereafter.

The Bermuda Weather Service has discontinued the Tropical Storm
Watch for Bermuda.


FORECAST POSITIONS AND MAX WINDS

INIT 22/1500Z 34.3N 63.0W 40 KT 45 MPH
12H 23/0000Z 34.8N 62.8W 40 KT 45 MPH
24H 23/1200Z 35.8N 61.2W 35 KT 40 MPH
36H 24/0000Z 37.2N 57.9W 35 KT 40 MPH
48H 24/1200Z 39.7N 52.9W 35 KT 40 MPH
60H 25/0000Z...DISSIPATED

$$
Forecaster Beven

[cycloneye]

Subtropical Storm Ana Discussion Number 3
NWS National Hurricane Center Miami FL AL012021
500 PM AST Sat May 22 2021

While Ana continues to produce convection near the center, the
amount of convection has decreased during the past several hours.
In addition, earlier scatterometer data and recent satellite
intensity estimates from TAFB suggest the cyclone has weakened.
The initial intensity is reduced to 35 kt.

A combination of increasing shear, dry air, and decreasing SSTs
should cause Ana to gradually weaken, and most of the global models
now show the system decaying to a trough in about 36 h. The new
intensity forecast calls for a slow weakening with dissipation
just after that time, and it is possible that Ana could dissipate
earlier than currently forecast.

Ana made a small counter-clockwise loop during the past few hours,
and the initial motion is now 050/4. A continued northeastward
motion at an increasing forward speed, due to the southwesterly
flow associated with a developing mid-latitude cyclone to the north
and northwest, is expected until the cyclone dissipates.


FORECAST POSITIONS AND MAX WINDS

INIT 22/2100Z 34.5N 62.4W 35 KT 40 MPH
12H 23/0600Z 34.9N 61.6W 35 KT 40 MPH
24H 23/1800Z 36.2N 59.0W 35 KT 40 MPH
36H 24/0600Z 38.3N 54.3W 30 KT 35 MPH
48H 24/1800Z...DISSIPATED

$$
Forecaster Beven

[cycloneye]

Subtropical Storm Ana Discussion Number 4
NWS National Hurricane Center Miami FL AL012021
1100 PM AST Sat May 22 2021

Ana continues to produce a small, but concentrated area of moderate
convection near its center. The storm remains embedded in a
large-scale upper-level trough axis, and convection near the center
has not been deep or expansive enough to result in significant
upper-level anticyclonic outflow. This structure suggests that the
system remains subtropical. However, scatterometer imagery also
indicates that Ana's radius of maximum winds is very small. A recent
METOP-B ASCAT pass at 0054 UTC had a peak wind retrieval of 36 kt
just southeast of Ana's center. Due to the small size of Ana's wind
field and allowing for some undersampling of this instrument, the
initial intensity was bumped up to 40 kt for this advisory.

Ana has begun to accelerate to the northeast and its initial motion
is now 050/8 kt. A continued northeastward motion at an increasing
forward speed is expected as deep-layer southwesterly steering flow
increases between a deepening mid-latitude trough to the northwest
and a subtropical high to the southeast.

The upper-level trough axis that Ana remains centered in has kept
the tiny cyclone in a small region of light upper-level flow,
allowing convection to persist near the center. However, as Ana
accelerates northeastward, this trough axis will gradually decay and
upper-level northerly flow is expected to increase after 12 h. The
resulting increase in northeasterly shear will import dry
mid-latitude air and likely strip away the remaining convection
associated with Ana by tomorrow night. The latest intensity forecast
calls for slow weakening after 12 h with dissipation by 48 h, though
it is possible that Ana could dissipate earlier than currently
forecast.

FORECAST POSITIONS AND MAX WINDS

INIT 23/0300Z 35.0N 61.4W 40 KT 45 MPH
12H 23/1200Z 35.8N 60.0W 40 KT 45 MPH
24H 24/0000Z 37.5N 56.3W 35 KT 40 MPH
36H 24/1200Z 41.1N 50.5W 35 KT 40 MPH
48H 25/0000Z...DISSIPATED

$$
Forecaster Papin/Brown

[Subtrop]

Tropical Storm Ana Discussion Number 5
NWS National Hurricane Center Miami FL AL012021
500 AM AST Sun May 23 2021

Satellite images indicate that Ana has contracted significantly
since yesterday and now has a compact area of moderate convection
around the center. Given the tight low-level circulation, small
radius of maximum wind, and compact central convection, Ana is
now estimated to have transitioned from a subtropical storm to a
tropical storm. The initial intensity remains 40 kt for this
advisory based on the earlier ASCAT data, which indicated that the
tropical-storm-force winds were confined to the south side of the
circulation.

Ana is not expected to be around much longer. The storm is headed
for an environment of lower SSTs, drier air, and increasing wind
shear. All of these factors should cause the compact cyclone to
lose strength and ultimately open into a trough in 24 to 36 hours.
In fact, some of the models suggest that the storm could dissipate
even sooner than that. The remnants of Ana will likely be absorbed
by a cold front on Monday.

The storm continues to increase its forward speed, and the initial
motion is now estimated to be 045/10 kt. A faster motion to the
northeast is expected until the cyclone dissipates.


FORECAST POSITIONS AND MAX WINDS

INIT 23/0900Z 35.7N 60.5W 40 KT 45 MPH
12H 23/1800Z 36.7N 58.7W 40 KT 45 MPH
24H 24/0600Z 39.4N 53.9W 35 KT 40 MPH
36H 24/1800Z...DISSIPATED

$$
Forecaster Cangialosi

[cycloneye]

Tropical Storm Ana Discussion Number 6
NWS National Hurricane Center Miami FL AL012021
1100 AM AST Sun May 23 2021

Ana is barely holding on as a tropical cyclone this morning, as the
core of the system has become devoid of organized deep convection. A
recent ASCAT overpass showed that wind field is slowly weakening,
with peak winds of 35 kt located just to the southeast of the
center. Based on this data, the initial advisory intensity has also
been decreased to 35 kt.

The cyclone is currently located over cool SSTs of about 20 degrees
C and surrounded by very dry air in the mid-troposphere. The
environmental conditions will only become more hostile through
tonight, as Ana gets caught between a digging mid- to upper-level
trough to its northwest and a strong subtropical upper-level jet to
its southeast. These features will impart increasing southwesterly
shear over the system by later today, and any convection that tries
to regenerate should be stripped away. Whatever is left of Ana's
low-level circulation should then open into a trough on Monday as it
becomes absorbed by a large approaching baroclinic zone
associated with the upper-trough.

The storm is now moving northeastward at 12 kt, and an accelerating
forward speed is anticipated until dissipation as Ana gets caught up
in increasing deep-layered southwesterly flow.


FORECAST POSITIONS AND MAX WINDS

INIT 23/1500Z 36.6N 59.4W 35 KT 40 MPH
12H 24/0000Z 38.0N 56.7W 35 KT 40 MPH
24H 24/1200Z 41.7N 50.3W 35 KT 40 MPH...POST-TROPICAL
36H 25/0000Z...DISSIPATED

$$
Forecaster Latto

[cycloneye]

Tropical Depression Ana Discussion Number 7
NWS National Hurricane Center Miami FL AL012021
500 PM AST Sun May 23 2021

Other than brief puff of convection late this morning, tiny Ana has
been devoid of organized deep convection for several hours. ASCAT
overpass data from this morning indicated that the peak winds had
deceased to 35 kt. Due to the lack of convection since that time,
it is reasonable to assume that the vortex has spun down a bit, and
therefore the initial advisory intensity has been lowered to 30 kt.

Ana is over cool waters and surrounded by very dry air in the
mid-troposphere. The brief convection that did occur today was
quickly stripped away, indicating that the anticipated increase in
shear has begun. Satellite imagery suggests that the circulation of
Ana is approaching a strong subtropical upper-level jet just to its
east, which is expected to produce even stronger shear over the
cyclone. These conditions should prevent further convection, if any,
from surviving, and the cyclone is expected to degenerate into a
remnant low by tonight. What is left of Ana's low-level circulation
should open into a trough on Monday as it is absorbed by a large
baroclinic zone approaching from the northwest.

The depression continues to accelerate northeastward, and the
forward motion is now northeastward at 15 kt. An accelerating
northwestward motion is anticipated until dissipation as Ana
gets caught up in increasing deep-layer southwesterly flow.


FORECAST POSITIONS AND MAX WINDS

INIT 23/2100Z 37.5N 57.7W 30 KT 35 MPH
12H 24/0600Z 39.4N 53.9W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 24/1800Z...DISSIPATED

$$
Forecaster Latto

[cycloneye]

Post-Tropical Cyclone Ana Discussion Number 8
NWS National Hurricane Center Miami FL AL012021
1100 PM AST Sun May 23 2021

Ana has mainly remained devoid of deep and organized convection
today, with only a couple of short-lived bursts noted in satellite
imagery earlier this morning. The cyclone has been an exposed cloud
swirl through the afternoon and evening hours, and Ana continues
moving into a hostile environment characterized by cool sea-surface
temperatures, dry mid-level air, and increasing vertical wind shear.
Thus, Ana has become a post-tropical cyclone, and this will be the
final NHC advisory on the system.

Although a recent ASCAT-B pass missed the center of post-tropical
Ana, it still shows an area of 30-35 kt winds in the southeast
quadrant of the low near the edge of the swath. Therefore, the
initial intensity is set at 35 kt, with the slightly stronger winds
likely just a product of the accelerating forward speed of the
system. The post-tropical cyclone is embedded in deep-layer
southwesterly flow and will continue to accelerate northeastward
until it opens up into a trough and becomes absorbed by a strong
baroclinic zone approaching from the northwest on Monday.

Additional information on post-tropical Ana can be found in High
Seas Forecasts issued by the National Weather Service, under AWIPS
header NFDHSFAT1, WMO header FZNT01 KWBC, and online at
ocean.weather.gov/shtml/NFDHSFAT1.php


FORECAST POSITIONS AND MAX WINDS

INIT 24/0300Z 38.3N 55.2W 35 KT 40 MPH...POST-TROPICAL
12H 24/1200Z 41.0N 50.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 25/0000Z...DISSIPATED

$$
Forecaster Reinhart/Brown