ATL: FIONA - Post-Tropical - Discussion

[tolakram]

visible floater https://weather.cod.edu/satrad/?parms=meso-meso1-02-96-1-100-1&checked=map&colorbar=undefined

[tolakram]

Shear is there, but not getting worse.



source: https://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=shr&zoom=Z&time=

use -3hr, +3hr to see changes, zoom to zoom out

[BobHarlem]

Center outrunning the convection which is getting sheared a bit.

[Category5Kaiju]

Oddly enough, mid-level shear seems virtually zippo where Fiona currently is. There's just a bit of deep layer shear since it's riding along the periphery between favorable and unfavorable zones. I guarantee you that if it was a bit further south and right under that 5 knot deep layer shear spot, then we would have been seeing something rather different.

[wxman57]

SUMMARY OF 200 AM AST...0600 UTC...INFORMATION
----------------------------------------------
LOCATION...16.5N 52.4W
ABOUT 625 MI...1005 KM E OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 14 MPH...23 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES

https://i.postimg.cc/NM7kx96z/D6-AA0097-AA30-46-C9-A70-F-2-E74-AF42-C203.png

Shifted to the south slightly.

Based on the cone it does not seem out of the question that Fiona could pass in between Puerto Rico and DR. In that case the islands could still get a lot of rain/wind, but Fiona's core might remain undisturbed and could thus intensify more than most models show right now.

Never use the 5-yr error cone for any impact predictions. It's meaningless for any storm. The cone represents only typical error over the past 5 seasons. It does not indicate any level of forecast certainty or uncertainty regarding the current storm, nor does it imply any impact region. Fiona will likely remain sheared as it passes through the NE Caribbean this weekend. As such, most, if not all, significant squalls and wind will be located northeast through southeast of the center. Don't expect too much near the center. This means the worst weather will occur after the center passes.

[skyline385]

Center exposed on visible

[Blown Away]

Fiona's LLC getting a bit more exposed IMO and maybe a just S of West movement now?

[BensonTCwatcher]

Definitely tilted, maybe on trying to de-couple the MLC if this keeps up . There is also still some mid level dry air upstream and another larger bit to the SW upstream that will certainly keep lid on things.

[PTrackerLA]

Can really see the decoupling occurring in a wider visible loop. IMO we will continue to see the ensemble envelopes shift west today.

[LarryWx]

https://i.imgur.com/sUMytX8.gif
Fiona's LLC getting a bit more exposed IMO and maybe a just S of West movement now?

Per satellite loops, it at least appears to be moving ever so slightly south of due west vs the 5AM NHC's ever so slight north of due west. It may very well be as far south as 16.5 or possibly even 16.4 N now though sometimes the satellite suggested location doesn't match the actual. If it is at 16.4-5 N, that would be slightly south (by ~15 miles) of the 5 AM implied 16.6-7 N now. If that's true (although 15 miles may not seem like much), that would imply a slight southward track adjustment at 11AM.

 Other opinions on a likely 11 AM track adjustment?

[SFLcane]

https://i.imgur.com/sUMytX8.gif
Fiona's LLC getting a bit more exposed IMO and maybe a just S of West movement now?

Per satellite loops, it at least appears to be moving ever so slightly south of due west vs the 5AM NHC's ever so slight north of due west. It may very well be as far south as 16.5 or possibly even 16.4 N now though sometimes the satellite suggested location doesn't match the actual. If it is at 16.4-5 N, that would be slightly south (by ~15 miles) of the 5 AM implied 16.6-7 N now. If that's true (although 15 miles may not seem like much), that would imply a slight southward track adjustment at 11AM.

 Other opinions on a likely 11 AM track adjustment?

Don't see any adjustments at 11am but as the post above mentioned i also think we will see the models gradually trend west given the exposed llc.

[Iceresistance]

The outflow is almost perfect!


https://s4.gifyu.com/images/tccapture.gif

[Blown Away]

https://i.imgur.com/sUMytX8.gif
Fiona's LLC getting a bit more exposed IMO and maybe a just S of West movement now?

Per satellite loops, it at least appears to be moving ever so slightly south of due west vs the 5AM NHC's ever so slight north of due west. It may very well be as far south as 16.5 or possibly even 16.4 N now though sometimes the satellite suggested location doesn't match the actual. If it is at 16.4-5 N, that would be slightly south (by ~15 miles) of the 5 AM implied 16.6-7 N now. If that's true (although 15 miles may not seem like much), that would imply a slight southward track adjustment at 11AM.

 Other opinions on a likely 11 AM track adjustment?

Don't see any adjustments at 11am but as the post above mentioned i also think we will see the models gradually trend west given the exposed llc.

NHC Forecasts:
8am - 16.6N - Moving 270
5am - 16.6N - Moving 270
11pm - 16.7N - Moving 280
5pm - 16.8N - Moving 280
11am - 16.6N - Moving 280

Fiona has not gained latitude since the first advisory yesterday and has moved due W (270) since. ECENS trending way W, a track adjustment likely at 11am with full impact into Hispaniola and out into SE Bahamas as maybe a TD moving NW at day 5. My amateur guess.

[AutoPenalti]

The outflow is almost perfect!

https://s4.gifyu.com/images/tccapture.gif
https://s4.gifyu.com/images/tccapture.gif

Yeah but it goes to show that shear is at the lower levels. So either the convection will start to chase the LLC or a new LLC will develop underneath it.

[NDG]

I have no doubt Fiona will tighten up and become more vertically stacked as it slows down some when it gets to the Lesser Antilles.
Earl started intensifying as well under 25 knots of shear.

[Iceresistance]

ASCAT direct hit!


https://s4.gifyu.com/images/ASCAT-direct-hit6704eda0970d3a3c.png

[LarryWx]

11 AM NHC kept it at 16.6N (straight west since last advisory). 

[wxman57]

Here's a plot of the latest NHC track (red) vs. consensus (TVCN) in blue. Looks like NHC may have one point a little too far south as it passes PR. Just a 0.1 deg north adjustment there would smooth out their track. Numbers are date/time (in CDT). They're staying right with consensus until it passes PR, then east of consensus. Their track is right on top of mine (which I didn't plot).

[Sciencerocks]

[aspen]

AF303 is about to take off for Fiona.