Tropical Storm Bret | peak 70mph 996mb| dissipated

[Ingyball]

It's not often that we get even the potential for an MDR tropical cyclone in June, but here we are. With SAL not showing up to the party yet and the warmth in the MDR, it's not too surprising. 

 

 

 

 

 

Edited June 25, 2023 by StretchCT

[StretchCT]

Just reinforcing the rarity of a June system in the main development region for the Tropical N Atlantic

These are the June tracks.

This is closer in on what has gone through a 500nm wide zone where the bubble is.

This is Ana

and Elsa

and no it is not lost on me that Ana and Elsa are their names.

[StretchCT]

Checking shear, which is pretty low in it's current path. Euro keeps the shear north of 15 until the storm creates it's own. 

[StretchCT]

Pretty rare that once they reach 80-90% that they don't develop

Indeed all intensity models are over naming threshold

 

[StretchCT]

May jump to a TS today.

 

[StretchCT]

Path is typical.  If it strengthens, recurve before islands. If not, through the islands.  US models (AVN, HMON, HWRF) have it strengthening and recurving. UK, NAV, CMC models are weaker and west. 

 

Euro brings it through the islands with max 40-45k winds.

[StretchCT]

Tropical Depression Three Advisory Number   1
NWS National Hurricane Center Miami FL       AL032023
1100 AM AST Mon Jun 19 2023

...TROPICAL DEPRESSION THREE FORMS OVER THE CENTRAL ATLANTIC...
...INTERESTS IN THE LESSER ANTILLES SHOULD MONITOR THIS SYSTEM...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...11.0N 40.3W
ABOUT 1425 MI...2295 KM E OF THE SOUTHERN WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 275 DEGREES AT 21 MPH...33 KM/H
MINIMUM CENTRAL PRESSURE...1009 MB...29.80 INCHES

 

Disco from advisory in spoiler

Spoiler

DISCUSSION AND OUTLOOK
----------------------
At 1100 AM AST (1500 UTC), the center of Tropical Depression Three
was located near latitude 11.0 North, longitude 40.3 West. The
depression is moving toward the west near 21 mph (33 km/h), and this
motion is expected to continue for the next several days.  On the 
forecast track, the system should be approaching the Lesser 
Antilles late this week.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Some strengthening is forecast, and the depression is forecast to 
become a hurricane in a few days.

The estimated minimum central pressure is 1009 mb (29.80 inches).

Forecast discussion in spoiler  - forecast to become a hurricane by the 22nd.

Spoiler

Tropical Depression Three Discussion Number   1
NWS National Hurricane Center Miami FL       AL032023
1100 AM AST Mon Jun 19 2023

Satellite images indicate that the tropical wave over the central 
Atlantic has become better organized this morning.  GOES-16 1-min 
visible imagery shows that the center has become well defined near 
a developing central dense overcast with prominent convective 
banding in the northern semicircle.  The initial intensity is set to 
30 kt, based on Dvorak estimates from SAB and TAFB, and recent 
satellite trends indicate this system is close to tropical-storm 
status.

The initial motion estimate is 275/18 kt, a bit uncertain because 
the center has just recently become trackable.  A large ridge of 
high pressure over the central Atlantic Ocean is forecast to cause 
the depression to move westward over the next several days. As the 
system nears the Lesser Antilles late this week, the ridge should 
weaken, causing the system to move more toward the west-northwest.  
However, there is considerable uncertainty in how much of a right 
turn could occur because it is somewhat tied to the intensity of the 
cyclone.  A stronger system would tend to move more to the right due 
to the upper-level flow, while a weaker system would continue more 
westward into the Caribbean.  For now, this forecast lies near the 
model consensus, and adjustments are likely in future advisories.  
This should be considered a low confidence track forecast since 
this type of forecast situation can result in large errors.

Environmental conditions appear conducive for strengthening over 
the next few days, with a much warmer than normal ocean in the 
depression's path, along with plentiful mid-level moisture and 
light shear.  This should promote strengthening through midweek.  
However, vertical wind shear is forecast to increase by most of the 
model guidance around day 3 in response to an upper-level trough.  
Thus the NHC forecast shows the intensity leveling off at the end 
of the forecast, consistent with the middle of the guidance 
envelope.  This intensity forecast is also more uncertain than 
normal, due to the differences in the model suite, along with the 
aclimatological nature of this system. 

KEY MESSAGES:

1. The depression is forecast to strengthen and move across the 
Lesser Antilles as a hurricane on Thursday and Friday, bringing a 
risk of flooding from heavy rainfall, hurricane-force winds, and 
dangerous storm surge and waves. 

2. Given the larger than usual uncertainty in the track forecast, 
it is too early to specify the location and magnitude of where 
these hazards could occur. However, everyone in the Lesser 
Antilles, Puerto Rico, and the Virgin Islands should closely monitor 
updates to the forecast for this system and have their hurricane 
plan in place. 



FORECAST POSITIONS AND MAX WINDS

INIT  19/1500Z 11.0N  40.3W   30 KT  35 MPH
 12H  20/0000Z 11.2N  42.9W   40 KT  45 MPH
 24H  20/1200Z 11.7N  45.9W   45 KT  50 MPH
 36H  21/0000Z 12.2N  48.6W   55 KT  65 MPH
 48H  21/1200Z 12.8N  51.2W   60 KT  70 MPH
 60H  22/0000Z 13.3N  53.9W   65 KT  75 MPH
 72H  22/1200Z 13.8N  56.3W   70 KT  80 MPH
 96H  23/1200Z 14.9N  61.5W   70 KT  80 MPH
120H  24/1200Z 16.5N  66.5W   65 KT  75 MPH

 

Edited June 19, 2023 by StretchCT

[Ingyball]

The storm is likely pretty close or already a TS in my opinion. I've seen this convective pattern quite often where it looks like the storm is about to have an "eye" and then you get a convective burst right over the center. It's not truly an eye at that point, but what happens when that convective burst matures is that the process of creating an eyewall begins. How long it takes to complete that eyewall determines whether or not the next time the storm does something similar reveals a true eye or if it has to do the same process a couple of times first. As of now it doesn't look like there is much to disrupt this process (mid-level shear can absolutely ruin this stage) so we should see it flourish today. 

[clm]

 

Edited June 19, 2023 by clm
Doh!  Put the wrong region in.  

[StretchCT]

ADT is at or above TS strength. We'll see if they name it.

[StretchCT]

 

Tropical Storm Bret Advisory Number   2
NWS National Hurricane Center Miami FL       AL032023
500 PM AST Mon Jun 19 2023

...TROPICAL STORM BRET FORMS OVER THE CENTRAL ATLANTIC...
...INTERESTS IN THE LESSER ANTILLES SHOULD MONITOR THIS SYSTEM...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...11.3N 42.2W
ABOUT 1295 MI...2085 KM E OF THE SOUTHERN WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 21 MPH...33 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES

Spoiler

Tropical Storm Bret Discussion Number   2
NWS National Hurricane Center Miami FL       AL032023
500 PM AST Mon Jun 19 2023

Satellite imagery continues to show that the system is becoming 
better organized. GOES 1-min data shows convective banding and a 
dense central overcast, with the low-level center embedded on the 
northwest side of the overcast.  Given the satellite trends and 
latest Dvorak estimates from SAB and TAFB, the initial intensity is 
set to 35 kt, and the depression is named Tropical Storm Bret.

Environmental conditions appear conducive for further strengthening 
over the next few days, with much warmer than normal SSTs along with 
plentiful mid-level moisture and light shear.  The NHC forecast 
continues to show a gradual increase in wind speed, similar to the 
model consensus.  However, vertical wind shear is forecast to 
increase by most of the model guidance on day 3 in response to an 
upper-level trough, along with more dry air nearby. Thus, the NHC 
forecast shows a slow weakening after that point while Bret is 
over the eastern Caribbean. There continues to be larger than usual 
uncertainty, due to the wide spread between the stronger regional 
hurricane models and weaker global guidance.

The initial motion estimate is 280/18 kt.  A large ridge of high 
pressure over the central Atlantic Ocean is forecast to cause Bret 
to move westward over the next several days. As the system nears the 
Lesser Antilles late this week, the ridge should weaken, causing the 
storm to move more toward the west-northwest.  The main source of 
track uncertainty continues to be tied to how strong Bret becomes, 
with the models farthest to the right (HWRF, HAFS) being stronger 
than the consensus, while the left-leaning models (ECMWF, UKMET) 
showing significant weakening at long range.  Given the large track 
and intensity spread, the NHC forecast remains near the model 
consensus, only a bit faster than the previous cycle. The latest
forecast remains a low confidence prediction.


KEY MESSAGES:

1. Bret is forecast to strengthen and move across the Lesser 
Antilles as a hurricane on Thursday and Friday, bringing a
risk of flooding from heavy rainfall, hurricane-force winds, and
dangerous storm surge and waves.

2. Given the larger than usual uncertainty in the track forecast,
it is too early to specify the location and magnitude of where
these hazards could occur. However, everyone in the Lesser
Antilles, Puerto Rico, and the Virgin Islands should closely monitor
updates to the forecast for Bret and have their hurricane
plan in place.


FORECAST POSITIONS AND MAX WINDS

INIT  19/2100Z 11.3N  42.2W   35 KT  40 MPH
 12H  20/0600Z 11.7N  44.8W   40 KT  45 MPH
 24H  20/1800Z 12.2N  47.7W   50 KT  60 MPH
 36H  21/0600Z 12.7N  50.3W   60 KT  70 MPH
 48H  21/1800Z 13.2N  52.9W   65 KT  75 MPH
 60H  22/0600Z 13.7N  55.5W   70 KT  80 MPH
 72H  22/1800Z 14.3N  58.3W   70 KT  80 MPH
 96H  23/1800Z 15.5N  63.6W   65 KT  75 MPH
120H  24/1800Z 17.0N  68.5W   60 KT  70 MPH

$$
Forecaster Blake/Kelly

 

[Ingyball]

One thing to watch as Bret enters the Caribbean, models have him interacting with a tropical upper tropospheric trough (TUTT) around Puerto Rico or Hispaniola.  TUTTs tend to spell trouble for tropical storms and hurricanes due to increased wind shear. However, a stronger hurricane like a high end cat-3 to cat-4 can actually run right trough a TUTT and break it apart. This leaves a favorable atmosphere for a storm after the fact and we've seen storms like Irma go crazy after breaking a TUTT. When a TUTT is extremely large and covers a good portion of the MDR and Caribbean that scenario is unlikely to happen. Right now the models have a narrow TUTT interacting with Bret, so if Bret is a major hurricane he might be able to ignore it and actually use the TUTT to his advantage down the road. This is what the HAFS A and B as well as the HWRF hint at. If Bret is a weak hurricane or tropical storm then the TUTT will likely spell the end of him. What Bret does over the next couple of days could drastically change what happens later this week.  

[MaineJay]

This is the time of year I go back to my TC bookmarks and lament what we lost from last year.   Did we really finally lose all but 1 polar orbiting satellite that scans the 85gHz frequency?  I know the TROPIC satellites were finally launched (after a previous rocket failed to deliver the first batch), but don't know their operational status.

Anywho, good convective blob on the eastern flank.

 

 

[StretchCT]

Bret has an exposed center, which is usually from either dry air or shear. Now if there was only displacement of convection on one side, I'd go with shear. Not sure what to make of this.  It looks like at the center, the tops are being blown south. 

I wouldn't say it's dry but there are pockets of dry air around.

Shear product from CIMSS is neutral, so it's probably shear. But 14kts isn't that much. ADT is pretty weak, just under TS. 

[StretchCT]

No longer forecast to reach hurricane level, though a burst of convection has improved it's look.

Spoiler

Tropical Storm Bret Discussion Number   6
NWS National Hurricane Center Miami FL       AL032023
500 PM AST Tue Jun 20 2023

A burst of deep convection developed over Bret's center during the 
past several hours, although a 1641 UTC AMSR2 microwave pass showed 
that most of the convective activity is located within a band 
wrapping around the east side of the circulation.  Based on the 
slightly improved convective structure, the initial intensity is 
raised to 40 kt, which is a blend of T2.5/35 kt and T3.0/45 kt 
Dvorak estimates from TAFB and SAB, respectively.

Despite upper-level cirrus clouds radiating away from the storm in 
all quadrants, it still appears that there is some westerly shear 
affecting the system below the cirrus level.  Global model 
forecasts suggest that this setup will continue for the next couple 
of days, but it shouldn't be strong enough to prevent some 
additional strengthening while Bret approaches the Lesser Antilles. 
The NHC intensity forecast is very close to the HCCA and IVCN 
consensus aids through 60 hours, and continues to show Bret 
crossing the islands as a 55-kt tropical storm.  Just after 
that time, Bret will be approaching an upper-level trough located 
over the eastern Caribbean Sea, and that feature is likely to cause 
more significant deep-layer shear over the storm by Friday.  
Because of the increase in shear, all of the global models show 
Bret opening up into a trough by day 4.  For continuity purposes, 
the official forecast continues to show a day 4 point, but it's 
likely that Bret will have dissipated by then.

The initial motion remains westward, or 280/17 kt.  There is very 
little change to the forecast track reasoning, with low- to 
mid-level ridging expected to steer Bret toward the west until it 
dissipates by day 4.  The track guidance has not shifted any 
farther south on this cycle, so the new NHC track forecast is very 
similar to the previous one.  Users are reminded that NHC's track 
forecasts have average errors of 60 to 75 n mi from 48 to 60 hours, 
and it is too soon to know exactly where Bret's center will move 
across the Lesser Antilles chain.


KEY MESSAGES:

1. Bret is forecast to approach the Lesser Antilles through 
Thursday morning and then move across the islands Thursday 
afternoon and Thursday night as a tropical storm, bringing a risk of 
flooding from heavy rainfall, strong winds, and dangerous waves 
along the coast.

2. Given the uncertainty in the track and intensity forecasts, it 
is too early to specify the location and magnitude of where Bret's 
associated hazards could occur.  A Tropical Storm Watch has been 
issued for Barbados, and additional watches are likely for other 
islands within the Lesser Antilles later tonight.


FORECAST POSITIONS AND MAX WINDS

INIT  20/2100Z 12.2N  48.6W   40 KT  45 MPH
 12H  21/0600Z 12.6N  50.8W   45 KT  50 MPH
 24H  21/1800Z 13.1N  53.4W   50 KT  60 MPH
 36H  22/0600Z 13.5N  55.9W   55 KT  65 MPH
 48H  22/1800Z 13.9N  58.8W   55 KT  65 MPH
 60H  23/0600Z 14.2N  62.0W   55 KT  65 MPH
 72H  23/1800Z 14.4N  65.6W   50 KT  60 MPH
 96H  24/1800Z 14.7N  73.0W   40 KT  45 MPH
120H  25/1800Z...DISSIPATED

$$
Forecaster Berg

Edited June 20, 2023 by StretchCT

[MaineJay]

Most recent microwave pass shows what appears to be a decent convective ring, perhaps displaced to the East a bit.  It's possible that the convection kinda randomly (but the best word) popped up in that configuration, and not really sustainable.

[Ingyball]

On 6/20/2023 at 9:57 AM, StretchCT said:

Bret has an exposed center, which is usually from either dry air or shear. Now if there was only displacement of convection on one side, I'd go with shear. Not sure what to make of this.  It looks like at the center, the tops are being blown south. 

I wouldn't say it's dry but there are pockets of dry air around.

Shear product from CIMSS is neutral, so it's probably shear. But 14kts isn't that much. ADT is pretty weak, just under TS. 

Yesterday morning was a combo effect of subsidence over the center due to convection to the west and east and a short term increase in low level steering currents along with a short term decrease in mid-level steering currents that gave the effect that the storm was sheared. 

[clm]

On 6/17/2023 at 10:52 AM, StretchCT said:

Just reinforcing the rarity of a June system in the main development region for the Tropical N Atlantic

These are the June tracks.

This is closer in on what has gone through a 500nm wide zone where the bubble is.

This is Ana

and Elsa

and no it is not lost on me that Ana and Elsa are their names.

In the last picture, which one is you?   The one on the left or right.  😁

[StretchCT]

Some recon

Drops

Vorts

HDOBS

[StretchCT]

4 hours ago, clm said:

In the last picture, which one is you?   The one on the left or right.  😁

Some days I identify as Elsa, others Ana.  Sometimes Olaf, sometimes Sven.  I mean it's a free country, right? 

[StretchCT]

NHC as to why 69kt winds were found at the surface but because they were under convection and possibly transient, so they are not elevating to a hurricane.

Spoiler

Tropical Storm Bret Discussion Number  12
NWS National Hurricane Center Miami FL       AL032023
500 AM AST Thu Jun 22 2023

Bret threw some interesting data at us during the couple of hours 
after the release of the previous advisory.  On the last pass of the 
Air Force Reserve Hurricane Hunter aircraft through Bret's center, 
the plane measured SFMR winds as high as 69 kt and a dropsonde 
surface pressure of 996 mb with 31 kt of wind.  Significant 
mid-level westerly shear is still affecting the system, and a 0539 
UTC AMSR2 microwave pass revealed a well-defined mid-level eye 
feature displaced about a degree to the east of Bret's low-level 
center.  It appears that the strong SFMR winds were measured beneath 
the strong convection in the western mid-level eyewall feature, so 
it's possible that they were transient and convectively driven.   
That said, Bret's initial intensity was raised to 60 kt on the 2 am 
intermediate advisory out of an abundance of caution, and that 
remains the current estimate.  Another reconnaissance aircraft is 
scheduled to investigate Bret in a few hours and will hopefully 
confirm whether or not the storm is still producing winds that 
strong.

Vertical shear is expected to gradually increase over the next 
couple of days as Bret approaches an upper-level trough located over 
the eastern Caribbean Sea.  The storm could maintain its intensity 
or fluctuate in intensity through much of today, but it is expected 
to begin weakening by tonight once it crosses the Lesser Antilles 
and moves over the eastern Caribbean Sea.  Global model fields 
indicate that Bret should degenerate into a trough over the central 
Caribbean Sea by day 3, which is shown in the official forecast.

There are no changes in the track forecast reasoning.  Bret is 
moving toward the west, or 280/13 kt, steered by a low- to mid-level 
ridge to its north.  An accelerated westward motion is expected 
during the next few days as Bret weakens, and the NHC track forecast 
is a little faster than the consensus aids, hedging toward the 
faster GFS and ECMWF solutions.  Users are reminded that NHC's track 
forecasts have average errors of about 40 n mi at 24 hours, and 
there is risk of strong winds and heavy rainfall for several islands 
within the Lesser Antilles regardless of exactly where the center 
crosses the island chain.


KEY MESSAGES:

1. Bret is forecast to approach the Lesser Antilles today and then 
move across those islands this evening and tonight as a strong 
tropical storm.

2. A Hurricane Watch and a Tropical Storm Warning are in effect 
for St. Lucia, and a Tropical Storm Warning is in effect for 
Martinique and Dominica.  There is a risk of flooding from heavy 
rainfall, strong winds, and dangerous waves along the coast within 
the warning area.  A Tropical Storm Watch remains in effect for 
Barbados and St. Vincent and the Grenadines.  Additional watches or 
warnings are possible for some islands in the Lesser Antilles later 
today.


FORECAST POSITIONS AND MAX WINDS

INIT  22/0900Z 13.7N  56.6W   60 KT  70 MPH
 12H  22/1800Z 13.9N  58.8W   60 KT  70 MPH
 24H  23/0600Z 14.1N  61.8W   55 KT  65 MPH
 36H  23/1800Z 14.3N  65.2W   50 KT  60 MPH
 48H  24/0600Z 14.4N  68.7W   45 KT  50 MPH
 60H  24/1800Z 14.6N  72.2W   40 KT  45 MPH
 72H  25/0600Z...DISSIPATED

$$
Forecaster Berg

[StretchCT]

Recon with a closed eye, 20nm wide and 63kt surface winds. 1005 mb

Spoiler

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 22nd day of the month at 12:16Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF97-5305
Storm Name: Bret
Storm Number & Year: 03 in 2023 (flight in the North Atlantic basin)
Mission Number: 3
Observation Number: 04

A. Time of Center Fix: 22nd day of the month at 11:24:40Z
B. Center Fix Coordinates: 13.80N 56.97W
B. Center Fix Location: 183 statute miles (295 km) to the ENE (75°) from Bridgetown, Barbados.
C. Minimum Height at Standard Level: 3,100m (10,171ft) at 700mb
D. Minimum Sea Level Pressure: 1005mb (29.68 inHg)
E. Dropsonde Surface Wind at Center: From 360° at 30kts (From the N at 35mph)
F. Eye Character: Closed
G. Eye Shape & Diameter: Circular with a diameter of 20 nautical miles (23 statute miles)
H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 63kts (72.5mph)
I. Location & Time of the Estimated Maximum Surface Wind Inbound: 1 nautical miles to the WNW (301°) of center fix at 11:24:00Z
J. Maximum Flight Level Wind Inbound: From 70° at 57kts (From the ENE at 65.6mph)
K. Location & Time of the Maximum Flight Level Wind Inbound: 93 nautical miles (107 statute miles) to the NW (313°) of center fix at 10:56:00Z
L. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 56kts (64.4mph)
M. Location & Time of the Estimated Maximum Surface Wind Outbound: 1 nautical miles to the ESE (114°) of center fix at 11:25:00Z
N. Maximum Flight Level Wind Outbound: From 185° at 34kts (From the S at 39.1mph)
O. Location & Time of the Maximum Flight Level Wind Outbound: 65 nautical miles (75 statute miles) to the SE (133°) of center fix at 11:44:30Z
P. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 9°C (48°F) at a pressure alt. of 3,052m (10,013ft)
Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 14°C (57°F) at a pressure alt. of 3,039m (9,970ft)
R. Dewpoint Temp (collected at same location as temp inside eye): 5°C (41°F)
R. Sea Surface Temp (collected at same location as temp inside eye): Not Available
S. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
S. Fix Level: 700mb
T. Navigational Fix Accuracy: 0.02 nautical miles
T. Meteorological Accuracy: 3 nautical miles

Remarks Section:
 

Maximum Flight Level Wind: 57kts (~ 65.6mph) which was observed 93 nautical miles (107 statute miles) to the NW (313°) from the flight level center at 10:56:00Z

 

[StretchCT]

Max winds of 80kts at 966mb.  That's 92mph at 1100-1200 feet.

Spoiler

 

[StretchCT]

Link to Barbados radar

https://www.barbadosweather.org/Composite/kidbuuComposite_Lionel_displayer2.php?Product=Reflectivity&Sector=EC_Bar&Composite=Sabre&ANISP=700&MAPP=1&PlanetOfTheApes=157944.91601772243

[StretchCT]

Almost to St Lucia/St Vincent