ATL: KARL - Post-Tropical - Discussion

[JaxGator]

The recent weakening was already forecast at the 5pm advisory and the intensity forecast is higher to 85mph due to the latest model runs. So we'll see if Karl will do by Monday. It's taken a dip south of west since the last advisory as well.

[sponger]

A recurving deep storm would be a huge wave maker for the east coast. A deepening system trapped under a strong ridge will spell trouble. The Francis/ Jeanne generator was fired up today and is ready for service if need be. Lets hope for a swell maker not a train wrecker!

[AutoPenalti]

HWRF, what a mess.

[Alyono]

looking at some layer mean wind analyses, I'm starting to wonder if this will clear the Caribbean. The models may have the vortex depth just a touch too deep.

It probably will clear the Caribbean as the shear is starting to drop off. But if it struggles with dry air, this will change things somewhat

Here is the low level layer mean wind

http://tropic.ssec.wisc.edu/real-time/d ... oom=&time=

[Hammy]

looking at some layer mean wind analyses, I'm starting to wonder if this will clear the Caribbean. The models may have the vortex depth just a touch too deep.

It probably will clear the Caribbean as the shear is starting to drop off. But if it struggles with dry air, this will change things somewhat

Here is the low level layer mean wind

http://tropic.ssec.wisc.edu/real-time/d ... oom=&time=

Could this pull a Gloria, staying weak until ~60W and then 'bouncing' off of the northern Islands so to speak?

[Alyono]

looking at some layer mean wind analyses, I'm starting to wonder if this will clear the Caribbean. The models may have the vortex depth just a touch too deep.

It probably will clear the Caribbean as the shear is starting to drop off. But if it struggles with dry air, this will change things somewhat

Here is the low level layer mean wind

http://tropic.ssec.wisc.edu/real-time/d ... oom=&time=

Could this pull a Gloria, staying weak until ~60W and then 'bouncing' off of the northern Islands so to speak?

Well, it first needs to reform a center. The ASCAT looks like an open wave

[Alyono]

the steaming pile of dog doodoo ECMWF has flipped AGAIN from a cat 4 to now barely a hurricane at Bermuda

When will this POC rightfully lose its reputation as a reliable model?

[cycloneye]

TROPICAL STORM KARL DISCUSSION NUMBER 16
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016
500 AM AST SUN SEP 18 2016

The structure of Karl has kept a similar appearance for some time
now with a small area of convection flaring up and down near the
center, with a larger mass of thunderstorms following the center in
the northeastern quadrant. The initial wind speed is held at 35 kt
using the last TAFB satellite estimate.

Karl's disorganized low-level structure will likely prevent much
intensification in the short term. However the environment
near the tropical cyclone is likely to become conducive for
strengthening within a couple of days due to lower shear, slightly
more moisture, and warmer sea surface temperatures. The intensity
guidance is very similar to the previous model cycle, and only
small changes were made to the previous NHC wind speed forecast.

The initial motion estimate is 255/10. A large subtropical high
over the central Atlantic should provide a fairly well-defined
steering current for the tropical storm over the next several days.
This ridge will likely turn Karl to the west later today and to the
west-northwest by early Tuesday through the end of the period.
Other than a small westward adjustment through 72 hours, the new
NHC track is similar to the previous one, near a model consensus
favoring the faster GFS/ECMWF solutions.


FORECAST POSITIONS AND MAX WINDS

INIT 18/0900Z 17.7N 42.3W 35 KT 40 MPH
12H 18/1800Z 17.7N 44.3W 35 KT 40 MPH
24H 19/0600Z 18.0N 47.0W 40 KT 45 MPH
36H 19/1800Z 18.6N 49.6W 40 KT 45 MPH
48H 20/0600Z 19.3N 52.2W 45 KT 50 MPH
72H 21/0600Z 21.5N 57.2W 55 KT 65 MPH
96H 22/0600Z 23.9N 62.1W 65 KT 75 MPH
120H 23/0600Z 26.5N 66.5W 75 KT 85 MPH

$$
Forecaster Blake

[Kazmit]

Since most models show Karl passing just south of Bermuda, a slight shift west in the track before recurving would send it right into them.

[Alyono]

well... it looks pathetic this morning. We have to take seriously the possibility this does not redevelop. Latest MU is basically keeping this as a wave. Look at the water vapor. Shear is decreasing. However, there is a LARGE amount of dry air over the center

[Kazmit]

[cycloneye]

 https://twitter.com/JimCantore/status/777469501461889024

[Kazmit]

I like how Cantore calls them rain tentacles . And yes, it is starting to look a little better now.

[caneman]

the steaming pile of dog doodoo ECMWF has flipped AGAIN from a cat 4 to now barely a hurricane at Bermuda

When will this POC rightfully lose its reputation as a reliable model?

I'm glad you said it. I've been saying it for years here. The mods should ban the term "king euro" on here as its both falliscious and misleading. There are a few members here that like to propagate this falsehood and are allowed to do so unfettered. The NHC uses a blend for a reason.

[GeneratorPower]

the steaming pile of dog doodoo ECMWF has flipped AGAIN from a cat 4 to now barely a hurricane at Bermuda

When will this POC rightfully lose its reputation as a reliable model?

It lost the reputation a few months ago in my mind. But before that, for many seasons, the Euro was right a huge amount of the time and smoked the GFS on countless occasions. The euro would always be out by itself with w different solution which eventually the other models would cave to. Not this year.

[Kazmit]

the steaming pile of dog doodoo ECMWF has flipped AGAIN from a cat 4 to now barely a hurricane at Bermuda

When will this POC rightfully lose its reputation as a reliable model?

It lost the reputation a few months ago in my mind. But before that, for many seasons, the Euro was right a huge amount of the time and smoked the GFS on countless occasions. The euro would always be out by itself with w different solution which eventually the other models would cave to. Not this year.

The Euro last year was quite accurate. Their win with the track of Joaquin heading out to sea was amazing. And usually they are right a lot of the time, but not this year.

[Kazmit]

12z GFS shows what looks like a direct hit on Bermuda.

[wxman57]

ASCAT from last evening didn't show a closed circulation. Karl does appear to have become an open wave. Don't know why the NHC would be hanging on to TS Karl, as it's not threatening any land areas, presently. Models had indicated last Wed/Thu that Karl would be weakening over the weekend due to increased shear & dry air in its path. This was not unexpected.

[abajan]

ASCAT from last evening didn't show a closed circulation. Karl does appear to have become an open wave. Don't know why the NHC would be hanging on to TS Karl, as it's not threatening any land areas, presently. Models had indicated last Wed/Thu that Karl would be weakening over the weekend due to increased shear & dry air in its path. This was not unexpected.

Assuming it's indeed currently an open wave and it later re-intensifies, it's likely to pass closer to the north of the Leeward Islands than earlier projected. Correct?

[cycloneye]

TROPICAL STORM KARL DISCUSSION NUMBER 17
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016
1100 AM AST SUN SEP 18 2016

The overall appearance of Karl has changed little in satellite
imagery since the previous advisory. However, recent water vapor
imagery suggest that the strong southwesterly shear that has been
plaguing the cyclone for the past few days is beginning to relax.
The initial wind speed is held at 35 kt based on a TAFB satellite
estimate of T2.5/35 kt. Ship BATFR18, which has been skirting the
eastern portion of Karl's circulation the past 12 hours, has
reported winds as high as 32 kt. That data has been helpful in
determining the extent of the 34-kt wind radius in the northeastern
quadrant.

Karl has trended westward and the initial motion estimate is now
270/11 kt. A deep-layer subtropical ridge over the central Atlantic
to the north of Karl is expected to keep the cyclone moving in a
general westward direction for the next 48 hours or so, followed by
west-northwestward motion during the remainder of the forecast
period. The new NHC track forecast is similar to the previous
advisory, and lies close to the various consensus model solutions.

Although Karl's convective pattern is currently somewhat disheveled
due to the hostile shear and dry mid-level conditions that the
cyclone has been encountering the past several days, the surface
wind field has remained remarkably robust, including a tight
inner-core. The GFS and ECMWF models are forecasting the vertical
wind shear to decrease to less than 5 kt from 24-120 hours, which
favors a strengthening trend, especially since Karl will be moving
29-30C SSTs during that time. However, only a marginally moist
mid-level environment is expected, a condition that could slow down
the intensification process. The official intensity forecast
follows the trend of the previous advisory, showing gradual
strengthening throughout the forecast period, and remains on the
conservative side close to the intensity consensus model IVCN.

FORECAST POSITIONS AND MAX WINDS

INIT 18/1500Z 18.0N 43.4W 35 KT 40 MPH
12H 19/0000Z 18.2N 45.5W 35 KT 40 MPH
24H 19/1200Z 18.6N 48.2W 40 KT 45 MPH
36H 20/0000Z 19.3N 50.9W 45 KT 50 MPH
48H 20/1200Z 20.2N 53.3W 50 KT 60 MPH
72H 21/1200Z 22.3N 58.4W 55 KT 65 MPH
96H 22/1200Z 24.7N 63.2W 65 KT 75 MPH
120H 23/1200Z 27.3N 66.7W 75 KT 85 MPH

$$
Forecaster Stewart

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