Tropical Storm Theta - MSW: 65mph... ENE at 8 mph... 989mb

[yoda]

Subtropical Storm Theta Discussion Number   1
NWS National Hurricane Center Miami FL       AL302020
300 AM GMT Tue Nov 10 2020

Over the past 12 h convection has slowly consolidated near the 
center of a non-tropical area of low pressure over the far 
northeast Atlantic. Earlier, there was a 2325 UTC ASCAT-B pass that 
showed that the low-level circulation had become more detached 
from the warm frontal boundary located to its northeast. In 
addition, the ASCAT pass showed that winds have increased to near 45 
kt on the southeast portion of the circulation near where coldest 
convective cloud tops were located. Both a 2137 UTC SSMIS and 2324 
UTC AMSU microwave pass showed convective banding under the cirrus 
canopy near where the highest winds were observed. However, water 
vapor satellite imagery still shows the presence of a broad 
upper-level low tangled up with the low-level circulation embedded 
in the convection. Therefore, Theta has been designated as a 
subtropical storm with maximum wind of 45 kt. 

Theta has been on a near due east heading over the last 12 h at 
90/13 kt. Currently the cyclone is located south of a broad 
deep-layer longwave trough. This trough is expected to bypass the 
cyclone to the east and Theta will primarily be steered by 
southwesterly flow on the northern periphery of a mid-level ridge 
centered over the Cape Verde islands. This flow will steer Theta 
slowly to the east-northeast over the next 3-5 days. The track 
guidance is in good agreement with this solution, with only minor 
differences in across-track spread. There are somewhat larger 
differences in the along-track spread related to different forward 
motion, but the latest NHC track forecast elected to stay close to 
the track consensus at this time.

Thetas structure has evolved from a frontal cyclone to a 
subtropical cyclone, though a frontal boundary remains nearby on the 
northeast side of the circulation. This boundary is expected to 
gradually dissipate and Theta is expected to fully transition to a 
tropical storm in 24 h as convection erodes the upper-level cyclonic 
flow overhead. The maximum sustained winds were increased slightly 
in the first 12 h of the forecast but are kept at 50 kt through 120 
h which is on the high end of the intensity guidance. 

Theta is the 29th named storm in the record-breaking 2020 Atlantic 
Hurricane Season, breaking the previous record of 28th named storms 
in 2005.


FORECAST POSITIONS AND MAX WINDS

INIT  10/0300Z 28.8N  40.3W   45 KT  50 MPH...SUBTROPICAL STORM
 12H  10/1200Z 29.0N  38.6W   50 KT  60 MPH...SUBTROPICAL STORM
 24H  11/0000Z 29.1N  36.3W   50 KT  60 MPH...TROPICAL STORM
 36H  11/1200Z 29.5N  34.3W   50 KT  60 MPH
 48H  12/0000Z 30.0N  32.6W   50 KT  60 MPH
 60H  12/1200Z 30.5N  30.7W   50 KT  60 MPH
 72H  13/0000Z 31.0N  28.7W   50 KT  60 MPH
 96H  14/0000Z 32.2N  24.3W   50 KT  60 MPH
120H  15/0000Z 33.3N  20.6W   50 KT  60 MPH

$$
Forecaster Papin/Brown

[yoda]

BULLETIN
Subtropical Storm Theta Advisory Number   1
NWS National Hurricane Center Miami FL       AL302020
300 AM GMT Tue Nov 10 2020

...SUBTROPICAL STORM FORMS OVER THE OPEN NORTHEAST ATLANTIC...
...RECORD-BREAKING 29TH NAMED STORM OF THE SEASON...


SUMMARY OF 300 AM GMT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...28.8N 40.3W
ABOUT 995 MI...1600 KM SW OF THE AZORES
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...E OR 90 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.


DISCUSSION AND OUTLOOK
----------------------
At 300 AM GMT (0300 UTC), the center of Subtropical Storm Theta was 
located near latitude 28.8 North, longitude 40.3 West. The storm is 
moving toward the east near 15 mph (24 km/h), and a general 
east-northeast motion is expected to continue during the next two to 
three days. 

Maximum sustained winds are near 50 mph (85 km/h) with higher gusts. 
Some slight strengthening is possible during the next 12 to 24 hours 
followed by little change in strength through Thursday. 

Winds of 40 mph extend outward up to 115 miles (185 km) from the
center.

The estimated minimum central pressure is 1000 mb (29.53 inches).


HAZARDS AFFECTING LAND
----------------------
None.


NEXT ADVISORY
-------------
Next complete advisory at 900 AM GMT.

$$
Forecaster Papin/Brown

[yoda]

[yoda]

BULLETIN
Subtropical Storm Theta Advisory Number   2
NWS National Hurricane Center Miami FL       AL302020
900 AM GMT Tue Nov 10 2020

...THETA EXPECTED TO REMAIN OVER THE EASTERN ATLANTIC FOR THE
NEXT SEVERAL DAYS...


SUMMARY OF 900 AM GMT...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...28.8N 39.5W
ABOUT 960 MI...1545 KM SW OF THE AZORES
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...E OR 90 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...998 MB...29.47 INCHES

[yoda]

Subtropical Storm Theta Discussion Number   2
NWS National Hurricane Center Miami FL       AL302020
900 AM GMT Tue Nov 10 2020

Theta has generally changed little during the past several hours.  
The cyclone has some characteristics of a tropical cyclone,
including a central dense overcast and a relatively small radius of
maximum wind.  However, the storm is still entangled with an
upper-level trough, and based on all of these factors, Theta is
being maintained as a subtropical storm.  The initial wind speed
remains 45 kt, which is at the high end of the satellite intensity
estimates.

The storm is moving due eastward at about 10 kt.  The track
forecast reasoning seems fairly straightforward.  A trough to the
north of the subtropical storm is expected to lift out, and Theta
should be steered eastward to east-northeastward during the next
several days on the north side of a mid-level ridge.  This motion
should take the cyclone across the subtropical eastern Atlantic
throughout the forecast period.  The models are in fairly good
agreement, and the NHC track forecast lies near the various
consensus aids.

Theta should transition to a tropical storm later today as it
separates from the upper-level trough.  Little change in intensity
is expected during the next several days due to mixed environmental
conditions.  Although Theta will be tracking over progressively
cooler SSTs and within moderate wind shear conditions, the air mass
is expected to remain unstable, which should be supportive of deep
convection.  The NHC intensity forecast is similar to the previous
one and lies near the high end of the model guidance.


FORECAST POSITIONS AND MAX WINDS

INIT  10/0900Z 28.8N  39.5W   45 KT  50 MPH
 12H  10/1800Z 28.9N  37.8W   50 KT  60 MPH
 24H  11/0600Z 29.2N  35.7W   50 KT  60 MPH
 36H  11/1800Z 29.7N  33.9W   50 KT  60 MPH
 48H  12/0600Z 30.4N  31.6W   50 KT  60 MPH
 60H  12/1800Z 31.0N  29.0W   50 KT  60 MPH
 72H  13/0600Z 31.4N  26.7W   45 KT  50 MPH
 96H  14/0600Z 32.2N  22.8W   45 KT  50 MPH
120H  15/0600Z 33.1N  19.9W   45 KT  50 MPH

$$
Forecaster Cangialosi

[Windspeed]

Text book subtropical storm...

[Orangeburgwx]

70mph

Sent from my LGL322DL using Tapatalk

[yoda]

Blake putting in some humor in the last advisory for Theta

 

Post-Tropical Cyclone Theta Discussion Number  23
NWS National Hurricane Center Miami FL       AL302020
300 PM GMT Sun Nov 15 2020

Theta has run out of theta-e.  The cyclone has been without 
significant deep convection for many hours now and has been 
gradually spinning down today. It no longer meets the qualifications 
of a tropical cyclone, so this is the last advisory.  The initial 
wind speed is set to 25 kt per the latest scatterometer pass.  

The low is meandering this morning.  It is expected to be picked up 
to the north-northeast by the next trough over the northeastern 
Atlantic, along with an increase in forward speed.  The remnants of 
Theta should gradually lose strength due to strong shear, very dry 
air and little instability before dissipating in a day or two. 

Additional information on this system can be found in High Seas
Forecasts issued by the UK Met Office under WMO header FQNT21 EGRR
and on the web at
metoffice.gov.uk/weather/specialist-forecasts/coast-and-sea/high-
seas-forecast/.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  15/1500Z 31.5N  18.2W   25 KT  30 MPH...POST-TROPICAL
 12H  16/0000Z 31.9N  18.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
 24H  16/1200Z 33.7N  17.7W   20 KT  25 MPH...POST-TROP/REMNT LOW
 36H  17/0000Z 36.5N  16.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 48H  17/1200Z...DISSIPATED
 
$$
Forecaster Blake