ATL: ISAIAS - Post-Tropical - Discussion

[CyclonicFury]

Interesting stats by Dr Klotzbach


https://twitter.com/philklotzbach/status/1290661583430070281

https://twitter.com/philklotzbach/status/1290496512300998656

https://twitter.com/philklotzbach/status/1290490504526721025

https://twitter.com/philklotzbach/status/1290487939378503680

So much for the U.S. being "off the hook" because Arthur missed landfall

[EquusStorm]

I want him to write a book with neat basin records and facts. Would pay top dollar for it

[GCANE]

109mph gust reported at Surf City, Long Beach Island, NJ in a tornadic thunderstorm just before 11am!

[GCANE]

A band just about to hit NYC.
Helicity 250

[artist]

Just heard they are having to make water rescues due to street flooding in Philly.

[Steve]

Just heard they are having to make water rescues due to street flooding in Philly.

https://www.inquirer.com/weather/live/h ... 00804.html

[weathaguyry]

Winds are gusting hard now on Southern Long Island. My roof tiles are starting to peel off, going to be an interesting few hours here.

[artist]

Stay safe, everyone.

[Bizzles]

Looks like the radar stations lost power here in NJ.

Haven't seen any update since around noon.

NWS shows "no data available"

[Bizzles]

Didn't know these existed, learn something new everyday. "Radar Status Message"

000
NOUS61 KPHI 041606
FTMDIX
Message Date: Aug 04 2020 16:23:19

KDIX is down due to a communications issue. Technicians are working to restore i
t as quickly as possible. No estimated time to return to service.

Looks like the radar stations lost power here in NJ.

Haven't seen any update since around noon.

NWS shows "no data available"

[syfr]

It would be helpful if someone knowledgeable could explain how it is this storm has stayed as strong as it has for so long. It's been interacting with land for a full day and still damaging.

[Bizzles]

It would be helpful if someone knowledgeable could explain how it is this storm has stayed as strong as it has for so long. It's been interacting with land for a full day and still damaging.

I'm sure someone will chime in with more detail but as far as I understand it has to do with the timing of the transition to extra-tropical and the position of the winter-like jetstream pumping energy into it.

[Steve]

It would be helpful if someone knowledgeable could explain how it is this storm has stayed as strong as it has for so long. It's been interacting with land for a full day and still damaging.

NHC has been mentioning this since I think Saturday in the forecast discussions. You can check their hurricane DISCUSSION archives for the exact wording. It's basically in the setup. You have a northward advancing tropical system running up against a SW flow ahead of a upper level trough moving across the Eastern US. This has the effect of consolidating the rain on the western and northern end of the system and forcing it north/nne ahead of the advancing trough and wringing moisture out of the system in the form of precip. I'm going to look it up for you because I'm a nice guy sometimes.

Actually they mentioned it again in the 11am discussion:

As Isaias moves north-northeastward through the Mid-Atlantic coast,
interaction with a strong upper-level jet maximum is forecast to
maintain the tropical storm's intensity longer than what typically
would be expected for inland decaying tropical cyclone. The global
models continue to indicate that Isaias is likely to produce
widespread tropical-storm conditions, with hurricane-force wind
gusts possible along the mid-Atlantic coast through this afternoon.
As a result, the gust factor at 12 h remains above the standard
20-percent value in the Forecast/Advisory Product (TCMAT4).

[Steve]

Here is 5pm from Sunday

Isaias is expected to maintain its
current intensity until landfall, and could restrengthen to
hurricane status in 24-36 h when the vertical shear vector is
forecast to switch from westerly to southwesterly which would align
the shear along the direction of storm motion. Some baroclinic
interaction is expected on days 2-3 when Isaias will move into the
right-rear quadrant of an anticyclonically curved jet streak, which
is expected to hold the intensity a little above what would normally
be expected for a post-landfall tropical cyclone. The NHC intensity
forecast is similar to the HFIP corrected consensus model and the
IVCN intensity consensus model, which agree well with the GFS and
ECMWF model intensity forecasts.

[GCANE]

 https://twitter.com/WeatherNation/status/1290695902861176833

[Visioen]

I feel like for his strenght Isaias is doing max damage

[Steve]

Here is 5pm from Sunday

Isaias is expected to maintain its
current intensity until landfall, and could restrengthen to
hurricane status in 24-36 h when the vertical shear vector is
forecast to switch from westerly to southwesterly which would align
the shear along the direction of storm motion. Some baroclinic
interaction is expected on days 2-3 when Isaias will move into the
right-rear quadrant of an anticyclonically curved jet streak, which
is expected to hold the intensity a little above what would normally
be expected for a post-landfall tropical cyclone. The NHC intensity
forecast is similar to the HFIP corrected consensus model and the
IVCN intensity consensus model, which agree well with the GFS and
ECMWF model intensity forecasts.

^^ That quadrant is an upward motion quadrant (e.g. you drew an x/y access or in other words a plus sign, two of the quadrants tend to inhibit development where 2 provide out flow and upward motion/air evacuation.
http://www.eumetrain.org/satmanu/four_q ... index.html

https://forecast.weather.gov/glossary.p ... 20quadrant

https://pdfs.semanticscholar.org/c6a0/a ... e8bae5.pdf

The physics are mostly too complicated for a semi-idiot like me, but I get the concept. That's why when people scream about shear is going to destroy storm x or y, many long-timers will mention that shear is relative to the position of the storm. While shear can certainly cut the hair of all thunderstorms trying to rise in the atmosphere, it can also provide an evacuation into the upper atmosphere such as what we are seeing with Isaias inland.

Here's a question. I don't think I've ever heard the term "jet streak" as many times as I have with Isaias. Maybe I haven't been paying attention all along. But it's a semi-new term for me that I don't think ever got this much mention.

[wx98]

Didn't know these existed, learn something new everyday. "Radar Status Message"

000
NOUS61 KPHI 041606
FTMDIX
Message Date: Aug 04 2020 16:23:19

KDIX is down due to a communications issue. Technicians are working to restore i
t as quickly as possible. No estimated time to return to service.

Looks like the radar stations lost power here in NJ.

Haven't seen any update since around noon.

NWS shows "no data available"

KDOX in Dover went down too. Isaias is trying to hide

[EquusStorm]

Jet streaks are a lot more important in severe weather meteorology than in the tropics I'd wager, can't think of that many more storms that were impacted in such a manner

[wx98]

Here is 5pm from Sunday

Isaias is expected to maintain its
current intensity until landfall, and could restrengthen to
hurricane status in 24-36 h when the vertical shear vector is
forecast to switch from westerly to southwesterly which would align
the shear along the direction of storm motion. Some baroclinic
interaction is expected on days 2-3 when Isaias will move into the
right-rear quadrant of an anticyclonically curved jet streak, which
is expected to hold the intensity a little above what would normally
be expected for a post-landfall tropical cyclone. The NHC intensity
forecast is similar to the HFIP corrected consensus model and the
IVCN intensity consensus model, which agree well with the GFS and
ECMWF model intensity forecasts.

^^ That quadrant is an upward motion quadrant (e.g. you drew an x/y access or in other words a plus sign, two of the quadrants tend to inhibit development where 2 provide out flow and upward motion/air evacuation.
http://www.eumetrain.org/satmanu/four_q ... index.html

https://forecast.weather.gov/glossary.p ... 20quadrant

https://pdfs.semanticscholar.org/c6a0/a ... e8bae5.pdf

The physics are mostly too complicated for a semi-idiot like me, but I get the concept. That's why when people scream about shear is going to destroy storm x or y, many long-timers will mention that shear is relative to the position of the storm. While shear can certainly cut the hair of all thunderstorms trying to rise in the atmosphere, it can also provide an evacuation into the upper atmosphere such as what we are seeing with Isaias inland.

Here's a question. I don't think I've ever heard the term "jet streak" as many times as I have with Isaias. Maybe I haven't been paying attention all along. But it's a semi-new term for me that I don't think ever got this much mention.

Ahhh, the good ole 4-Quad Jet Theory and Atmospheric Continuity. Dynamics is fun