ATL: FIONA - Post-Tropical - Discussion

[NDG]

To be honest I thought the mlc would have detached by now with all the sw shear. Surprised that it's still hanging on. Not sure about the open wave scenario, llc looks rather healthy at the moment.

It hasn't detached because the low level stream is considerable slow right now so the MLC is able to keep up with the LLC, otherwise it would had decoupled by now.

[tolakram]

live loop, still hanging on

http://weather.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-E%20HURRICANE&lat=22&lon=-47&info=vis&zoom=1&width=1024&height=725&type=Animation&quality=90&palette=ir1.pal&numframes=5&map=county&mapcolor=gray&map=none

[Nimbus]

Convection is on the wane now and shear is absolutely shredding the outflow just a degree or two north of Fiona.
That weakness just has to dig a little more for the forecast to verify but if she keeps tracking west of 50 with these periodic bursts who knows..

[NDG]

Convection is on the wane now and shear is absolutely shredding the outflow just a degree or two north of Fiona.
That weakness just has to dig a little more for the forecast to verify but if she keeps tracking west of 50 with these periodic bursts who knows..

And very dry air is now being absorbed by the circulation, might be indeed looking at just a TD by tonight.

[Ntxw]

Yeah the shear with the dry air is going to take a toll. Not as good as she looked this morning.

[cycloneye]

TROPICAL STORM FIONA DISCUSSION NUMBER 16
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062016
500 PM AST SAT AUG 20 2016

Fiona's center has again become partially exposed this afternoon in
response to strong southwesterly shear of about 30 kt. A blend of
the latest Dvorak estimates from TAFB and SAB, and ADT values from
CIMSS at the University of Wisconsin, support holding the initial
intensity at 35 kt for this advisory. Continued hostile upper-level
winds along with dry air along the path of the storm should induce a
weakening trend, and Fiona is still expected to weaken to a tropical
depression tonight or Sunday. The ECMWF model opens this system
into a trough during the next few days, while some of the other
models hold onto a closed low through the period. If Fiona survives
the strong shear during the next 48 hours, there is a possibility
that the system could continue as a weak tropical cyclone for the
next several days. The official intensity forecast is similar to the
previous one, and leans toward the ECMWF model solution.

Fiona has jogged a bit to the right, and it is now moving
northwestward at about 13 kt. The forecast reasoning remains
unchanged from the earlier forecasts, as the low- to mid-level
subtropical ridge over the central Atlantic should keep Fiona moving
west-northwestward for the next several days. The NHC track
forecast is similar to the previous one and is in best agreement
with the multi-model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT 20/2100Z 21.2N 49.1W 35 KT 40 MPH
12H 21/0600Z 22.1N 51.0W 35 KT 40 MPH
24H 21/1800Z 23.1N 53.6W 30 KT 35 MPH
36H 22/0600Z 24.1N 56.2W 30 KT 35 MPH
48H 22/1800Z 25.0N 58.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 23/1800Z 27.0N 62.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 24/1800Z 29.5N 65.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 25/1800Z...DISSIPATED

$$
Forecaster Cangialosi/Latto

[Kazmit]

Fiona's still hanging on I see, I'm impression she's still a TS. This recent image of Fiona from the satellite loop shows a possible eye-like feature.

[Kingarabian]

That LLC is exposed

[tolakram]

Another burst, doesn't want to quit.

live ir

http://weather.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-E%20HURRICANE&lat=22&lon=-48&info=ir&zoom=1&width=1024&height=725&type=Animation&quality=90&palette=ir3.pal&numframes=10&map=county&mapcolor=gray&map=none

[Hammy]

This could've been another Danny 2015 type storm if the upper environment was favorable--that's quite a tight circulation despite the shear and dry air.

[stormwise]

looks very to the weak ssw and likely to open up .

[cycloneye]

TROPICAL STORM FIONA DISCUSSION NUMBER 17
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062016
1100 PM AST SAT AUG 20 2016

Somewhat surprisingly, two recent ASCAT passes showed that Fiona is
producing 45-kt winds in its northeastern quadrant. This intensity
is also supported by the latest ADT estimate. Despite the increase
in maximum winds, the next 36 hours will be critical for Fiona's
survival as a tropical cyclone. During this period, westerly shear
of 30 kt will be at its strongest, and mid-level relative humidities
will be at their lowest. Therefore, gradual weakening is
anticipated, and it's entirely possible that Fiona could soon
struggle to maintain organized deep convection. For now, the NHC
official forecast shows Fiona becoming a remnant low by 72 hours.
However, there is a lot of uncertainty in this forecast. If Fiona
can survive the next 36 hours, it might persist as a weak tropical
cyclone through the end of the forecast period since environmental
conditions do become a little more favorable in a couple of days. It
should be noted that most of the global models hang onto a weak low
for at least the next 5 days, with the exception of the ECMWF which
shows the low opening up into a trough by 48 hours. For now, the
NHC forecast continues to show dissipation by day 5 as a compromise.

Fiona's motion has been wavering between west-northwest and
northwest, and the latest estimate is 305/13 kt. Low-level ridging
should keep Fiona on this general trajectory for the next 72 hours
or so, followed by a northwestward turn with a decrease in speed by
day 4 when the cyclone approaches a stalled frontal boundary off
the east coast of the United States. The NHC official forecast has
been nudged south and west to be closer to the TVCN multi-model
consensus, especially toward the end of the forecast period.

FORECAST POSITIONS AND MAX WINDS

INIT 21/0300Z 21.7N 50.1W 45 KT 50 MPH
12H 21/1200Z 22.4N 52.0W 45 KT 50 MPH
24H 22/0000Z 23.3N 54.6W 40 KT 45 MPH
36H 22/1200Z 24.2N 57.3W 40 KT 45 MPH
48H 23/0000Z 24.9N 59.5W 35 KT 40 MPH
72H 24/0000Z 26.6N 63.3W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 25/0000Z 29.0N 66.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
120H 26/0000Z...DISSIPATED

$$
Forecaster Berg

[galaxy401]

Actually, she's at her strongest yet now.

BULLETIN
TROPICAL STORM FIONA ADVISORY NUMBER 17
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062016
1100 PM AST SAT AUG 20 2016

...SATELLITE DATA SHOW THAT FIONA IS PRODUCING 50-MPH WINDS...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...21.7N 50.1W
ABOUT 825 MI...1330 KM ENE OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
At 1100 PM AST (0300 UTC), the center of Tropical Storm Fiona was
located near latitude 21.7 North, longitude 50.1 West. Fiona is
moving toward the northwest near 15 mph (24 km/h). A
west-northwestward motion at a similar forward speed is expected
during the next couple of days.

Satellite wind data indicate that maximum sustained winds are near
50 mph (85 km/h) with higher gusts. Gradual weakening is forecast
during the next 48 hours.

Tropical-storm-force winds extend outward up to 60 miles (95 km)
from the center.

The estimated minimum central pressure is 1004 mb (29.65 inches).


HAZARDS AFFECTING LAND
----------------------
None.


NEXT ADVISORY
-------------
Next complete advisory at 500 AM AST.

$$
Forecaster Berg

[Hammy]

Interesting having the winds up, it's in line with what the models were showing a day or so ago.

[Hammy]

00z GFS shows Fiona weakening in the short term but maintaining itself, possibly re-intensifying as a TS near Bermuda. This would be interesting should 99L develop as I don't recall when the last time we had three active systems was.

[stormwise]

No way is FIONA stronger LOL infact as i was thinking looking @ the ascat posted a few posts above it was about to open up. You guys are to funny.

[LarryWx]

That looks to me like a combo of the remnants of Fiona and 99L not moving much between FL & Bermuda on day 10 on the 0Z Euro

[USTropics]

Fiona was just decapitated, just a naked swirl right now:

[abajan]

Fiona was just decapitated, just a naked swirl right now:

http://i.imgur.com/5lvSnUP.gif

One of the easiest to locate naked swirls I've seen in a while.

[cycloneye]

TROPICAL STORM FIONA DISCUSSION NUMBER 18
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062016
500 AM AST SUN AUG 21 2016

After the earlier convective bursting episode and resultant spin up
of the low-level wind field, strong westerly shear of at least 30 kt
has stripped away the convective cloud shield, leaving a fully
exposed low-level circulation center that is easy to locate.
Assuming some spin down of the circulation due to the loss of
convection, the initial intensity has been lowered to 40 kt.

Now that Fiona's circulation has become a little more shallow, the
low-level center has turned more westward and the cyclone is now
moving 295/14 kt. The global models are in good agreement on a
mid-level ridge to the north and northeast of Fiona remaining in
place for the next few days, which should keep the small cyclone
moving in a general west-northwest direction through 72 hours. After
that time, the western portion of the ridge is expected to weaken
due to an approaching frontal system, which should allow Fiona or
its remnant circulation to slow down and turn northwestward. The new
track forecast is essentially just an update of the previous
advisory track, and lies close to the TVCN consensus model forecast.

During the next 24 hours or so, Fiona is forecast to traverse
through a band of strong westerly to northwesterly vertical wind
shear of 25-30 kt and dry mid-level air with humidity values near 40
percent. As a result, gradual weakening is expected due to the small
cyclone likely not being able to sustain deep convection for long
periods of time. The new intensity forecast holds onto the previous
trend of Fiona weakening into a remnant low by 72 hours. However, a
lot of uncertainty remains with this intensity forecast. Strong
instability that will be present due to very warm SSTs of 29C-30C
and a cool upper-level troposphere, which could produce periodic
bursts of intense convection that could sustain the low-level vortex
until environmental become more favorable for strengthening on days
4 and 5. Most of the global models continue to depict a weak low for
at least the next 5 days, except for the ECMWF model, which weakens
Fiona to an open trough by 48 hours. The NHC intensity remains a
compromise of these extremes and shows dissipation by day 5.

FORECAST POSITIONS AND MAX WINDS

INIT 21/0900Z 22.2N 51.7W 40 KT 45 MPH
12H 21/1800Z 22.9N 53.7W 35 KT 40 MPH
24H 22/0600Z 23.8N 56.3W 35 KT 40 MPH
36H 22/1800Z 24.5N 58.6W 35 KT 40 MPH
48H 23/0600Z 25.3N 60.7W 30 KT 35 MPH
72H 24/0600Z 27.0N 64.2W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 25/0600Z 29.7N 66.3W 30 KT 35 MPH...POST-TROP/REMNT LOW
120H 26/0600Z...DISSIPATED

$$
Forecaster Stewart