STS Alpha

[Windspeed]

The NHC actually consulted with the Portuguese Institute of Sea and Atmosphere prior to classifying STS Alpha. Just speculation here but this was likely already a STC well before classification. I'd imagine in post analysis it will be backtracked into yesterday for posterity as that is when the STC had first started showing signs of having transitioned.

Quote

Special information
Communication valid between 2020-09-18 16:47:00 and 2020-09-18 23:59:00
Subject: Alpha subtropical cyclone
The depression centered along the coast of the district of Leiria, gained subtropical characteristics during the afternoon, revealing an organized structure in the satellite images. The NHC contacted the IPMA to conduct a joint assessment of the situation, and it was decided to name the cyclone. This cyclone was named Alpha. According to the projections of the different models, after entering the land, the Alpha should rapidly lose intensity.

With the approach of the depression to the coast, it was possible to monitor the cyclone with the aid of the radar system, making it possible to identify very high winds in altitude, but relatively close to the surface. Taking into account the elements available at the moment, it was decided to raise the warning level to orange for warnings of wind, precipitation and thunder in the directly affected districts, Leiria and Coimbra.

Taking into account the worsening of the meteorological situation, it is recommended to monitor the forecast and meteorological warnings over the next few hours, consulting:

http://www.ipma.pt/pt/otempo/prev.descritiva/
http: // www .ipma.pt / en / otempo / prev.significativa
http://www.ipma.pt/pt/otempo/prev-sam/

For more details on the forecast for maritime navigation consult:

http://www.ipma.pt/pt/maritima/boletins/

Edition date: 2020-09-18 16:47:38
Ministry of the Sea

Portuguese Institute of Sea and Atmosphere, IP
Rua C, Lisbon Airport
1749-077 Lisbon - Portugal

 

[HillsdaleMIWeather]

It just dropped a nice big tornado in Portugal 

https://twitter.com/MeteoTrasMontPT/status/1306914280252542976?s=20

 

[Windspeed]

2 minutes ago, HillsdaleMIWeather said:

It just dropped a nice big tornado in Portugal 

https://twitter.com/MeteoTrasMontPT/status/1306914280252542976?s=20

 

Wow that's a mean looking stovepipe! 

[hlcater]

6 minutes ago, HillsdaleMIWeather said:

It just dropped a nice big tornado in Portugal 

https://twitter.com/MeteoTrasMontPT/status/1306914280252542976?s=20

 

some mad girth on that one

[Sickman]

Is iCyclone headed to Lisbon???

[mattb65]

4 hours ago, Hoosier said:

What are the people who use male/female pronouns to refer to tropical systems going to do with the greek alphabet storms?  

I better not see Alpha referred to as he and Beta as she.  

Not sure why but the first thing that came to mind when you posted this was...

 

[CheeselandSkies]

4 hours ago, hlcater said:

some mad girth on that one

That's what she said.

[SnowLover22]

In regards to Subtropical cyclones, I wonder why this is 

Quote

Subtropical cyclones with hurricane-force winds of 33 m/s, (119 km/h, 64 knots, or 74 mph) or greater are not officially recognized by the National Hurricane Center. Once a subtropical storm intensifies enough to have hurricane-force winds, it is then automatically assumed to have become a fully tropical hurricane.

Is it because it is assumed that it is a meteorological impossibility for there to be a subtropical storm that has at least 74 mph winds?

 

Upon further research, it seems there was a subtropical storm that was not classified as a tropical storm that had wind speeds at 70 mph. So is it that far-fetched that you could have a "Subtropical hurricane"? Sorry about being off topic. I have just wondered about this for a while.

@Windspeed

Quote

Throughout May 1972, a series of weak troughs moved across the eastern United States. In the third week of the month, an upper-level cutoff low developed along one of these troughs, located southeast of the United States and removed from the Westerlies. The origins of Alpha were from a surface low northeast of Florida, associated with the larger-scale, cold core upper low.^[1][2] It organized, and late on May 23 it could be classified as a subtropical depression, east of the Georgia/South Carolina border.^[3] While southeast of Hatteras, North Carolina, a developing ridge blocked its northeast motion, and so it slowed to turn to the southeast. On May 25, a small, intense low-level center organized rapidly, and by the next day it attained gale force winds, by which time the storm turned southwestward.^[2] At 1600 UTC on May 26, the National Hurricane Center initiated advisories on Subtropical Cyclone Alpha, when the storm was about 225 miles south of Cape Hatteras.^[4] Around that time, it reached its peak winds of 70 mph (110 km/h).^[3]

 

[das]

Saved here for posterity...

[Sickman]

On 9/20/2020 at 11:55 PM, SnowLover22 said:

In regards to Subtropical cyclones, I wonder why this is 

Is it because it is assumed that it is a meteorological impossibility for there to be a subtropical storm that has at least 74 mph winds?

 

Upon further research, it seems there was a subtropical storm that was not classified as a tropical storm that had wind speeds at 70 mph. So is it that far-fetched that you could have a "Subtropical hurricane"? Sorry about being off topic. I have just wondered about this for a while.

@Windspeed

 

If a subtropical storm strengthens enough to have 74+ mph winds, then it's getting that type of energy from either a barotropic or baroclinic source, not a messy combination of both.  In addition, at that wind speed, it would be pretty much physically impossible for it to not become more fully tropical, since angular momentum would lead to enhanced convection near the center, thus warming the core.

Of course, this example is for a storm that started as subtropical, not a tropical storm or hurricane that has begun to acquire some extratropical characteristics.