ATL: HARVEY - Post-Tropical - Discussion

[tolakram]

Saved RGB loop

[Hurricaneman]

Looks like I see some inflow around 12n 36w which means this is organizing as far as track I think something in between the GFS and Euro

[chaser1]

I'm loving the fact that the models can't get a handle on the genesis of this system; it means there is nothing for us to do except sit back and watch it develop on satellite. Feels like old times. I'm going to get out a paper tracking chart and my weather radio to celebrate!

Gotta love a "throw-back" kinda year!

[Michele B]

"Satellite pictures and upper-air data indicate that Hurricane Andrew formed from a tropical wave that crossed from the west coast of Africa to the tropical North Atlantic Ocean on 14 August 1992. The wave moved westward at about 20 kt, steered by a swift and deep easterly current on the south side of an area of high pressure. The wave passed to the south of the Cape Verde Islands on the following day. At that point, meteorologists at the National Hurricane Center (NHC) Tropical Satellite Analysis and Forecast (TSAF) unit and the Synoptic Analysis Branch (SAB) of the National Environmental Satellite Data and Information Service (NESDIS) found the wave sufficiently well-organized to begin classifying the intensity of the system using the Dvorak (1984) analysis technique." From: http://www.nhc.noaa.gov/1992andrew.html

Interesting dates, huh?

This one reminds me of Andrew - A LOT!

[Emmett_Brown]

 https://twitter.com/MJVentrice/status/897142119361642498




I guess the same could be said for the Euro!

[Alyono]

 https://twitter.com/MJVentrice/status/897142119361642498




I guess the same could be said for the Euro!

except most every model is now showing the same...

[SouthFLTropics]

 https://twitter.com/MJVentrice/status/897142119361642498




I guess the same could be said for the Euro!

except most every model is now showing the same...

Yeah, looks like he may have pulled the trigger a little too quick on that Tweet. With that said, I still think 91L has a good shot at development as it heads further west.

[Steve]

He said he was all in with development again yesterday or Saturday.

[otowntiger]

 https://twitter.com/MJVentrice/status/897142119361642498




I guess the same could be said for the Euro!

except most every model is now showing the same...

LOL! There is no trusting the models this year it seems. Although I still think the rest of August will be less active than normal and that may continue thru the season. Just my gut and 2 cents.

[Alyono]

He said he was all in with development again yesterday or Saturday.

Ventrice emphasizes Kelvin Waves FAR FAR too much. It is understandable, though, as that was his dissertation topic. He wants to see his theory validated in the real world in a forecasting sense.

However, I am reminded of the old QBO relationship that said a westerly QBO means more intense Atlantic hurricanes. Turned out, Gray did not have a large enough sample size. Won't be able to make this conclusion on Ventrice's theory for maybe 20 more years when we get a larger sample size

[nativefloridian]

"Satellite pictures and upper-air data indicate that Hurricane Andrew formed from a tropical wave that crossed from the west coast of Africa to the tropical North Atlantic Ocean on 14 August 1992. The wave moved westward at about 20 kt, steered by a swift and deep easterly current on the south side of an area of high pressure. The wave passed to the south of the Cape Verde Islands on the following day. At that point, meteorologists at the National Hurricane Center (NHC) Tropical Satellite Analysis and Forecast (TSAF) unit and the Synoptic Analysis Branch (SAB) of the National Environmental Satellite Data and Information Service (NESDIS) found the wave sufficiently well-organized to begin classifying the intensity of the system using the Dvorak (1984) analysis technique." From: http://www.nhc.noaa.gov/1992andrew.html

Interesting dates, huh?

This one reminds me of Andrew - A LOT!

[RL3AO]

He said he was all in with development again yesterday or Saturday.

Ventrice emphasizes Kelvin Waves FAR FAR too much. It is understandable, though, as that was his dissertation topic. He wants to see his theory validated in the real world in a forecasting sense.

I think there's something there. After a CCKW passage, you see low-level westerly anomalies and upper-level easterly anomalies. But, if those anomalies are only a couple m/s, it probably won't be enough to turn an unfavorable environment favorable. Over a large sample size, I suspect we will see a slightly higher likelihood of genesis following a Kelvin wave, but it's not the golden answer. The same with the MJO. There is some signal of increased genesis when MJO filtered negative VP anomalies are over the Atlantic. Maybe it nudges net favorability slightly to more likely, but if there are other large scale negatives...well you can't polish a turd.

[gatorcane]

It appears the "center" (13N, 35W) is gaining some latitude while the entire trough moves west:

[Alyono]

He said he was all in with development again yesterday or Saturday.

Ventrice emphasizes Kelvin Waves FAR FAR too much. It is understandable, though, as that was his dissertation topic. He wants to see his theory validated in the real world in a forecasting sense.

I think there's something there. After a CCKW passage, you see low-level westerly anomalies and upper-level easterly anomalies. But, if those anomalies are only a couple m/s, it probably won't be enough to turn an unfavorable environment favorable. Over a large sample size, I suspect we will see a slightly higher likelihood of genesis following a Kelvin wave, but it's not the golden answer. The same with the MJO. There is some signal of increased genesis when MJO filtered negative VP anomalies are over the Atlantic. Maybe it nudges net favorability slightly to more likely, but if there are other large scale negatives...well you can't polish a turd.

Heard today that there still may be too much SAL and dry air to allow for anything in the Tropical Atlantic.

I will make note that the three eastern MDR systems we have had so far all had extremely favorable localized dynamics. Bret and Don formed from an unusually strong monsoon trough adding vorticity, while TD Four formed from an Indian-Ocean type westerly wind burst. We nearly saw a twin cyclone off of Brazil south of the equator with that burst. Given that with those ridiculously favorable localized dynamics, these systems lasted for such a short period of time should have been raising red flags about the tropical Atlantic, instead of saying that means an active season is coming. I myself missed that

[wxman57]

This disturbance, like Franklin before it, will be struggling against dry air until it moves west of 70W. That means low development chances east of the Caribbean. If it can reach the NW Caribbean or pass north of the Caribbean and head toward the Bahamas, then it may have a good chance of developing.

Here's a NASA forecast valid 18Z today. Look near 13N/35W.

[tarheelprogrammer]

This disturbance, like Franklin before it, will be struggling against dry air until it moves west of 70W. That means low development chances east of the Caribbean. If it can reach the NW Caribbean or pass north of the Caribbean and head toward the Bahamas, then it may have a good chance of developing.

Here's a NASA forecast valid 18Z today. Look near 13N/35W.

http://weather.graphics/nasa/2017081312 ... ntic_6.png

Is that amount of dry air normal for this time of the year?

[SoupBone]

This disturbance, like Franklin before it, will be struggling against dry air until it moves west of 70W. That means low development chances east of the Caribbean. If it can reach the NW Caribbean or pass north of the Caribbean and head toward the Bahamas, then it may have a good chance of developing.

Here's a NASA forecast valid 18Z today. Look near 13N/35W.

[img]/img]

Bahamas? So I guess you're not on board the Franklin path train yet? BTW, when's the first Texas cold front?

[wxman57]

This disturbance, like Franklin before it, will be struggling against dry air until it moves west of 70W. That means low development chances east of the Caribbean. If it can reach the NW Caribbean or pass north of the Caribbean and head toward the Bahamas, then it may have a good chance of developing.

Here's a NASA forecast valid 18Z today. Look near 13N/35W.

[img]/img]

Bahamas? So I guess you're not on board the Franklin path train yet? BTW, when's the first Texas cold front?

No, it's not normal, though there was a stronger SAL outbreak 3-4 years ago in August.

[wxman57]

This disturbance, like Franklin before it, will be struggling against dry air until it moves west of 70W. That means low development chances east of the Caribbean. If it can reach the NW Caribbean or pass north of the Caribbean and head toward the Bahamas, then it may have a good chance of developing.

Here's a NASA forecast valid 18Z today. Look near 13N/35W.

[img]/img]

Bahamas? So I guess you're not on board the Franklin path train yet? BTW, when's the first Texas cold front?

I wouldn't rule out a track toward the Bahamas, but I'd forecast a Caribbean track today.

[Alyono]

This disturbance, like Franklin before it, will be struggling against dry air until it moves west of 70W. That means low development chances east of the Caribbean. If it can reach the NW Caribbean or pass north of the Caribbean and head toward the Bahamas, then it may have a good chance of developing.

Here's a NASA forecast valid 18Z today. Look near 13N/35W.

http://weather.graphics/nasa/2017081312 ... ntic_6.png

Is that amount of dry air normal for this time of the year?

That is 2013 territory there for the tropical Atlantic

HOWEVER, the western part of the basin, including the subtropical western Atlantic, appears to be significantly more favorable than 2013