Low pressure trough east of the Bahamas (Is Invest 98L)

[AJC3]

Oh wow! That is too cool for school! I see the multiple vortices you highlighted with the yellow x's. Is the bigger area of clouds in the front, part of these multiple vortices ?

It's a BI/BE (baroclincally initiated/enhanced) frontal wave. It's trying to develop in an the area where the strongest upper level forcing resides. It could take on some tropical characteristics, hence its mention in the TWO the last few days.

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
700 PM EST Thu Nov 7 2024

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Active Systems:
The National Hurricane Center is issuing advisories on Hurricane
Rafael, located over the southeastern Gulf of Mexico.

Near the Virgin Islands:
A trough of low pressure located near and north of the Virgin
Islands continues to produce disorganized showers and
thunderstorms. Some gradual development of this system is possible
during the next couple of days while it moves westward near the
Greater Antilles. Regardless of development, locally heavy rains
are possible across the northern Leeward Islands, the Virgin
Islands, Puerto Rico, Hispaniola, and the southeastern Bahamas
through Saturday.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 7 days...low...20 percent.

$$
Forecaster Beven

[AJC3]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
700 AM EST Fri Nov 8 2024

Near Greater Antilles:
Disorganized showers and thunderstorms continue in association with
a trough of low pressure that extends from the central Caribbean Sea
northeastward across Hispaniola and into the southwestern Atlantic.
Some gradual development of this system is possible during the next
couple of days while it moves westward near the Greater Antilles.
Regardless of development, locally heavy rains are possible across
the Virgin Islands, Puerto Rico, Hispaniola, and the southeastern
Bahamas through Saturday.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 7 days...low...20 percent.

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
100 PM EST Fri Nov 8 2024

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Active Systems:
The National Hurricane Center is issuing advisories on Hurricane
Rafael, located over the central Gulf of Mexico.

1. Near Greater Antilles:
Disorganized showers and thunderstorms continue in association with
a trough of low pressure that extends from near Hispaniola
northeastward over the southwestern Atlantic. Development, if any,
of this system should be slow to occur during the next couple of
days while it moves westward to west-northwestward near the Greater
Antilles, Turks and Caicos Islands, and the southeastern Bahamas.
Regardless of development, locally heavy rains are possible across
the Virgin Islands, Puerto Rico, Hispaniola, Turks and Caicos
Islands, and the southeastern Bahamas through Sunday.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...low...10 percent.


Forecaster Reinhart

[MarioProtVI]

This is reminding me very much of Oscar. Small system, persistent convection and what seems to be a developing LLC. No way this is only 10/10. Yet another possible small TC that might be missed.

[Hurricane2022]

And this time we don't have any close radar to track any interesting feature under the convection. Unless this develops an eye and/or an ASCAT pass shows a closed circulation and 30+ kt winds I don't see any upgrade to TD/S status coming from the NHC very soon.

[underthwx]

This is reminding me very much of Oscar. Small system, persistent convection and what seems to be a developing LLC. No way this is only 10/10. Yet another possible small TC that might be missed.

https://media.discordapp.net/attachments/1158173473861025862/1304543077716983848/49158417.gif?ex=672fc5ea&is=672e746a&hm=728c96a8ac298318800814c4e254dbb07e0c55467ff176d25b0a00b803ea66d2&

It sure does look like it's getting organized, assuming that conditions in its path are favorable for development, maybe the percentages will nudge upwards over the next few days? Quite an outro for the 2024 season, with this feature, and maybe more?

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
700 PM EST Fri Nov 8 2024

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Active Systems:
The National Hurricane Center is issuing advisories on Hurricane
Rafael, located over the central Gulf of Mexico.

1. Near Greater Antilles:
Disorganized showers and thunderstorms continue in association with
a trough of low pressure that extends from near Hispaniola
northeastward over the southwestern Atlantic. Development, if any,
of this system should be slow to occur during the next couple of
days while it moves westward to west-northwestward near the Greater
Antilles, Turks and Caicos Islands, the southeastern Bahamas, and
eastern Cuba. Regardless of development, locally heavy rains are
possible across the Virgin Islands, Puerto Rico, Hispaniola, Turks
and Caicos Islands, the southeastern Bahamas, and eastern Cuba
through Sunday.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...low...10 percent.


Forecaster Beven

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
700 AM EST Sat Nov 9 2024

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Active Systems:
The National Hurricane Center is issuing advisories on Tropical
Storm Rafael, located over the central Gulf of Mexico.

1. Near the Bahamas:
A trough of low pressure located a couple of hundred miles east of
the central Bahamas is producing disorganized showers and
thunderstorms. Development, if any, of this system should be slow to
occur during the next day or two while it moves westward to
west-northwestward. Regardless of development, locally heavy rains
and gusty winds are possible across the Bahamas through Sunday.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...low...10 percent.


Forecaster Cangialosi

[NDG]

AOI is still very interesting this morning.

[AJC3]

AOI is still very interesting this morning.

https://i.imgur.com/Mn8DlZN.gif

Shorty, anyone?

I generally don't take issue with folks I used to coordinate with...especially here, where we try (usually in vain) to keep people from snarking at/piling on NHC. However, this looks to be pretty close to being a tropical depression. It just needs to close off a wind center while convection persists. It's titled SW-NE, and the last few ASCAT passes show that it's still open trough.



However, it's at the northern edge of a small bubble of low shear.



Given the early morning trends, 10/10 seems a tad low to me for this critter.

[NDG]

AOI is still very interesting this morning.

https://i.imgur.com/Mn8DlZN.gif

Shorty, anyone?

I generally don't take issue with folks I used to coordinate with...especially here, where we try (usually in vain) to keep people from snarking at/piling on NHC. However, this looks to be pretty close to being a tropical depression. It just needs to close off a wind center while convection persists. It's titled SW-NE, and the last few ASCAT passes show that it's still open trough.

https://i.imgur.com/YoZuuZh.png

However, it's at the northern edge of a small bubble of low shear.

https://i.imgur.com/4Iovgau.jpeg

Given the early morning trends, 10/10 seems a tad low to me for this critter.

Lets see if this morning's ASCAT pass caught it.

[MarioProtVI]

AOI is still very interesting this morning.

https://i.imgur.com/Mn8DlZN.gif

Shorty, anyone?

I generally don't take issue with folks I used to coordinate with...especially here, where we try (usually in vain) to keep people from snarking at/piling on NHC. However, this looks to be pretty close to being a tropical depression. It just needs to close off a wind center while convection persists. It's titled SW-NE, and the last few ASCAT passes show that it's still open trough.

https://i.imgur.com/YoZuuZh.png

However, it's at the northern edge of a small bubble of low shear.

https://i.imgur.com/4Iovgau.jpeg

Given the early morning trends, 10/10 seems a tad low to me for this critter.

I would not use OSCAT as it is unreliable and has a closed circ bias, same as the HY one which it is related to IIRC.

[cycloneye]

Stayed at 10/10.

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
100 PM EST Sat Nov 9 2024

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Active Systems:
The National Hurricane Center is issuing advisories on Tropical
Storm Rafael, located over the central Gulf of Mexico.

1. Near the Bahamas:
A concentrated area of showers and thunderstorms a couple of hundred
miles east of the central Bahamas is associated with a trough of low
pressure. Some gradual development of this system is possible
during the next day or so before it moves into unfavorable
environmental conditions on Sunday. Regardless of development,
locally heavy rains and gusty winds are possible as it moves
generally westward across the Bahamas through Sunday.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...low...10 percent.


Forecaster Cangialosi

[AJC3]

I would not use OSCAT as it is unreliable and has a closed circ bias, same as the HY one which it is related to IIRC.

From everything I've read, it does not have a closed circulation bias, but has a high wind speed bias at higher speeds.

From: https://mdc.coaps.fsu.edu/scatterometry ... esults.pdf

The Oceansat-3 OSCAT instrument performs well and good quality winds can be retrieved
› Coastal processing yields consistent results; it will be used in our processing, unlike for ScatSat-1
› The innermost and outermost full resolution slices in the footprints (eggs) appear to have slightly inconsistent σ0 values and they are not used in the wind retrievals for now;
› Outer azimuth peak at 180o needs further attention
› The wind statistics w.r.t. ECMWF winds are comparable to those from ScatSat-1
› Both HY-2B and Oceansat-3 show an increasing positive wind speed bias for higher wind speeds, this trend is stronger for Oceansat-3 than for HY-2B.
› The NSCAT4-HY2 GMF results in a flatter wind speed bias as a function of wind speed, but slightly deteriorates the wind direction and u/v statistics. It works better for HY-2B than for Oceansat-3.
› Backscatter data can be corrected with HOC prior to the wind inversion. This results in a flatter wind speed bias as a function of wind speed, but at the same time a negative overall wind speed bias and a deterioration of the wind speed bias as a function of WVC number and also a deterioration of the wind direction and u/v statistics. This effect is stronger for Oceansat-3 than for HY-2B.
› Retrieved wind speeds can also be corrected using HOC. This results in a flatter wind speed bias without introducing overall biases and without changing the wind direction and u/v statistics.
› QuikSCAT shows an increasing wind speed bias for higher wind speeds, comparable in magnitude to Oceansat-3, ASCAT shows an almost flat wind speed bias for high wind speeds.
› OPS* improves differences between scatterometer and ECMWF model winds

When you think about it, a scatterometer having a "closed circulation bias" wouldn't make any sense. Either it would have higher than normal ambiguities in direction, irrespective of a closed LLC, or it wouldn't. If you can point me to another study of this instrument which mentions this alleged "bias" of which you speak, I'll take a look. I'm always willing to reconsider my position in the face of solid evidence to the contrary.

[tropicwatch]

Invest 98L is that right?

[AnnularCane]

Invest 98L is that right?

A little birdie told me so.

[AJC3]

Invest 98L is that right?

Correct! Invest 98L is up.