ATL: KARL - Post-Tropical - Discussion

[gatorcane]

Tight clustering but look at the dotted black line which is movement of the system from 00z best track. It is clear models think the system is deeper than it really is

[stormreader]

I too think it's possible now that Karl just won't be able to get its act together over the next few days. Based on proximity of ULL and the way the season has developed so far. In that case the wave/invest that we now call Karl may drift along W to WNW generally toward the Bahamas and S Fl as the wave that became Hermine did (and the invest which followed Hermine). Both of those systems moved as disorganized waves into the GOM. Hermine found better conditions in the GOM, the subsequent invest did not. But a disorganized wave should continue WNW over the long haul, or possibly even dissipate if the influence of the trough actually stretches it out.

[floridasun78]

Tight clustering but look at the dotted black line which is movement of the system from 00z best track. It is clear models think the system is deeper than it really is

issue that still moving west let see turn were forecast models show it KARL weaker system that models showing

[centuryv58]

Tight clustering but look at the dotted black line which is movement of the system from 00z best track. It is clear models think the system is deeper than it really is

It is certainly thinking outside of the box!!

[wxman57]

There is some really strong bursting to the east of the LLC. I would not be surprised to see the center reform there.

I don't see the center reforming east. I think any increased organization will have to wait a day or two until the shear relaxes.

[floridasun78]

let see nhc have say their still have it getting be hurr soon start track to wnw and nw soon and north by Bermuda on sat and ne by sunday

[Alyono]

Not only is Karl not a TS now, an argument could be made that it lacks the convective organization required to be called a TC

[stormreader]

Not only is Karl not a TS now, an argument could be made that it lacks the convective organization required to be called a TC

Yes. Just an open wave tracking W to WNW across the open Atlantic. Wouldn't give these models (which forecast typical hurricane development and re curvature) a lot of credence right now. Based on what we've seen so far this year, a wave worth our attention would seem to be the order of the day, and the season.

[cycloneye]

TROPICAL STORM KARL DISCUSSION NUMBER 27
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016
1100 PM AST TUE SEP 20 2016

Karl continues to struggle this evening. Satellite images indicate
that the low-level center of the storm is completely exposed to the
southwest of the main area of deep convection. The NOAA Hurricane
Hunters investigated Karl earlier this evening and found that the
maximum winds were still around 35 kt, though a very recent ASCAT
pass suggests that this estimate could be a bit generous.

Dropsonde data and model vertical cross sections indicate that Karl
is being affected by mid-level southwesterly flow and dry air
induced by a cut-off low pressure system located a few hundred
miles to the west. These unfavorable atmospheric conditions have
been affecting the cyclone during the past several days and until
these conditions abate, little change in the structure or strength
of Karl is anticipated. The models insist that environment should
become less hostile in about 24 h, and Karl should have its best
opportunity to intensify late this week and this weekend when it
moves into an area of baroclinic forcing. The NHC intensity
forecast is identical to the previous one, and lies near the middle
of the guidance envelope.

The tropical storm has moved basically due west during the past 24
hours. A turn toward the northwest should occur on Wednesday
when the cyclone nears the southwestern periphery of a deep-layer
ridge, followed by a northward motion in about 3 days when Karl
rounds the ridge and moves into a pronounced weakness. By the end
of the forecast period, a sharp increase in speed and turn to the
northeast are expected as a large-scale mid-latitude trough
picks up the tropical cyclone. There are significant forward speed
differences in the models associated with how Karl interacts with
the large-scale trough in the 3 to 5 day time frame, and the
NHC forecast is of low confidence during that period.

FORECAST POSITIONS AND MAX WINDS

INIT 21/0300Z 19.9N 56.7W 35 KT 40 MPH
12H 21/1200Z 20.9N 58.2W 35 KT 40 MPH
24H 22/0000Z 22.9N 60.7W 40 KT 45 MPH
36H 22/1200Z 24.5N 62.9W 45 KT 50 MPH
48H 23/0000Z 25.9N 64.8W 55 KT 65 MPH
72H 24/0000Z 29.0N 65.0W 70 KT 80 MPH
96H 25/0000Z 32.9N 59.6W 85 KT 100 MPH
120H 26/0000Z 39.2N 48.2W 80 KT 90 MPH

$$
Forecaster Cangialosi

[Hammy]

On the basis of what data are they retaining this as a TS?

[floridasun78]

Lisa look nicer and KARL

[floridasun78]

AT2

BULLETIN
TROPICAL STORM KARL ADVISORY NUMBER 27
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016
1100 PM AST TUE SEP 20 2016

...NOAA HURRICANE HUNTER AIRCRAFT INDICATES THAT KARL HAS
NOT STRENGTHENED...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...19.9N 56.7W
ABOUT 385 MI...620 KM ENE OF THE LEEWARD ISLANDS
ABOUT 990 MI...1595 KM SSE OF BERMUDA
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES
still moving west!!!!!!!!!!!!!!!!!!!

[floridasun78]

The tropical storm has moved basically due west during the past 24
hours. A turn toward the northwest should occur on Wednesday
when the cyclone nears the southwestern periphery of a deep-layer
ridge, followed by a northward motion in about 3 days when Karl
rounds the ridge and moves into a pronounced weakness. By the end of the forecast period

[floridasun78]

so let see turn by wed afternoon to nw

[SapphireSea]

I would say that the LLC is in progress to dissipate. Not sure if there will be some sort of new wave axis nearer to convection. But the persistent westerly course would indicate the system is completely unstacked and whatever is at the surface has no mid to upper structure.

[AutoPenalti]

The tropical storm has moved basically due west during the past 24
hours. A turn toward the northwest should occur on Wednesday
when the cyclone nears the southwestern periphery of a deep-layer
ridge, followed by a northward motion in about 3 days when Karl
rounds the ridge and moves into a pronounced weakness. By the end of the forecast period

The forecast had called for it to move WNW in the afternoon, here we are 12 hours later with a due west movement.

[floridasun78]

The tropical storm has moved basically due west during the past 24
hours. A turn toward the northwest should occur on Wednesday
when the cyclone nears the southwestern periphery of a deep-layer
ridge, followed by a northward motion in about 3 days when Karl
rounds the ridge and moves into a pronounced weakness. By the end of the forecast period

The forecast had called for it to move WNW in the afternoon, here we are 12 hours later with a due west movement.

let see wnw to nw track start soon on wed afternoon

[Shuriken]

Karl's center is now only a few degrees of longitude from clipping the northeast corner of the Hebert Box. The lack of vertical structure is keeping the storm on a stubborn westward track.

[cycloneye]

TROPICAL DEPRESSION KARL DISCUSSION NUMBER 28
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016
500 AM AST WED SEP 21 2016

Karl's structure is very difficult to determine this morning.
Satellite data indicate that the low-level center moved westward
far away from the convection, and currently it is hard to say if
Karl possess a closed circulation or not. Assuming that it still
does, the maximum winds are estimated generously at 30 kt, since the
cloud pattern has become less organized. I would not be surprised if
early visible satellite images will reveal that the cyclone has
degenerated into a broad area of low pressure.

Global models have totally failed so far in forecasting the
upper-level winds surrounding Karl. The upper-low near Karl which
unanimously all models have been forecasting to weaken is still
strong and producing shear over the cyclone. Given such a resilient
shear pattern, additional weakening is anticipated today. However,
most of the models are still predicting a favorable pattern for
intensification, and on this basis as well as continuity, the NHC
forecast calls for some strengthening beyond 36 hours while Karl
moves away from the hostile tropics. By the end of the forecast
period, Karl should be rapidly losing tropical characteristics
while it interacts with the mid-latitude flow.

The initial motion is also highly uncertain, giving that we have
been following the low-cloud swirl defining the alleged center. The
best estimate is toward the west or 280 degrees at 12 kt. Karl is
approaching the southwestern edge of the subtropical ridge, and this
pattern should result in a turn to the northwest and then north
during the following two days. After that time, a sharp recurvature
is anticipated around the northwestern portion of the subtropical
high and ahead of a mid-latitude shortwave. This sharp recurvature
is the solution provided by most of the track models, and the NHC
forecast is in the middle if the guidance envelope.

FORECAST POSITIONS AND MAX WINDS

INIT 21/0900Z 20.2N 57.6W 30 KT 35 MPH
12H 21/1800Z 20.9N 59.3W 25 KT 30 MPH
24H 22/0600Z 23.0N 61.5W 30 KT 35 MPH
36H 22/1800Z 25.0N 64.0W 35 KT 40 MPH
48H 23/0600Z 27.0N 65.5W 45 KT 50 MPH
72H 24/0600Z 30.0N 64.0W 60 KT 70 MPH
96H 25/0600Z 35.5N 56.5W 75 KT 85 MPH
120H 26/0600Z 43.0N 42.0W 65 KT 75 MPH...POST-TROP/EXTRATROP

$$
Forecaster Avila

[cycloneye]

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