ATL: FLORENCE - Post-Tropical - Discussion

[northjaxpro]

Still watching this very closely. I am still very concerned that Florence could still shift southward and more west. The ridging in place is quite stout and I still have a bad vibe some of the reliable models have not handled the ridge's strength. We will.find out with future runs the next 24-36 hours. Still so many variables in play. Keep your guard up people in the entire East Coast frpm NE Florida north up along the entire East Coast

[LarryWx]

Despite my feeling the chances of being heavily impacted in my area are down significantly from how it looked Friday and despite every major 0Z model (except the NAVGEM) being upper SC northward, the last 2 EPS and GEPS having a nontrivial # of members hitting CHS south to N FL and what appears to be Flo still moving S of due W (I think she now may be down to 24.3 N), are keeping me from reducing that chance further right now.

Note on the new EPS how the slowest developing members are tending to be on the southern side of the band of tracks. Look closely near 68W at how many more blue members there are on the southern end of the band vs the mainly red ones (stronger) on the northern end. That map is also telling me that if Flo is still not back N of 25.0N by the time she reaches 60W (she's near 55.5W now), she'd then be within the southern 1/3 or so of the members and a little S of the operational likely meaning southerly adjustments on the Euro to come.

[LarryWx]

The 5AM NHC advisory has Flo down from 25.6N at 11 PM to 25.5N now. I had guessed maybe as far south as 25.3. So, not as far S as I was guessing.

[JarrodB]

Anyone have a link to a floater satellite since the NHC no longer provides one?

[toad strangler]

Anyone have a link to a floater satellite since the NHC no longer provides one?

Tropical Tiidbits has them! Super easy.

[AxaltaRacing24]

Anyone have a link to a floater satellite since the NHC no longer provides one?

http://www.ssd.noaa.gov/PS/TROP/floater ... oater.html

[JarrodB]

Anyone have a link to a floater satellite since the NHC no longer provides one?

http://www.ssd.noaa.gov/PS/TROP/floater ... oater.html

Thank you. Exactly what i was looking for.

[KWT]

Looks like Flo is wrapping up, deep convection much more widespread today as well, though still not deep enough to suggest any RI like the GFS is suggesting right now should be happening.

[cycloneye]

BULLETIN
Tropical Storm Florence Advisory Number 40
NWS National Hurricane Center Miami FL AL062018
500 AM AST Sun Sep 09 2018

...FLORENCE EXPECTED TO BECOME A HURRICANE TODAY...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...24.5N 55.8W
ABOUT 765 MI...1235 KM SE OF BERMUDA
ABOUT 640 MI...1030 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...989 MB...29.21 INCHES




Tropical Storm Florence Discussion Number 40
NWS National Hurricane Center Miami FL AL062018
500 AM AST Sun Sep 09 2018

Florence's cloud pattern has continued to gradually become better
organized overnight, with an increase in convection near the center
and a developing central dense overcast feature. However, the
cloud tops are not particularly cold and the outer banding features
remain fragmented likely due to some nearby dry mid-level air.
Dvorak intensity estimates from TAFB and SAB range from 55 to 65
kt, so the initial intensity remains 60 kt, just shy of hurricane
strength. The NOAA Hurricane Hunters are scheduled to investigate
the storm later today, and that data should provide a better
assessment of Florence's intensity.

The upper-level outflow is becoming well established over the
cyclone, and the global model guidance indicates that Florence
will remain in a very favorable upper-level environment while the
cyclone moves over the warm waters over the southwestern
Atlantic. These conditions favor strengthening with the only
apparent negative factor being nearby dry air, which will likely
remain away from the inner core due to the low shear conditions.
The NHC intensity forecast again calls for a period of rapid
strengthening within the next 12-36 hours, and Florence is forecast
to become a major hurricane on Monday with additional strengthening
early in the week. This means that Florence is likely to be a very
powerful hurricane as it moves over the western Atlantic toward the
southeastern United States. The new NHC intensity forecast is near
the various intensity consensus aids and is very similar to the
previous official forecast.

Florence is currently located between a couple of mid-level ridges
and a slow westward motion is expected today. Another strong
high pressure ridge is forecast to build to the north of Florence
on Monday, which should cause the storm to begin moving
west-northwestward to northwestward at an increasingly faster
forward speed. The dynamical model guidance is tightly clustered
for the first 2-3 days with increasing spread thereafter. The GFS
remains along the right side of the guidance envelope with the HWRF
and ECMWF bracketing the left edge. It should be noted that both
the GFS and ECMWF ensemble means are a little to the left or west
of their operational runs. As a result, the NHC track forecast
lies to the left of the TVCA multi-model consensus, but is not as
far to the west as the FSSE and HCCA corrected consensus models at
day 5. The models are in agreement that Florence is likely to slow
down near the end of the forecast period as a blocking high
pressure ridge builds to the north of the hurricane.

Key Messages:

1. Florence is forecast to be a dangerous major hurricane near the
southeast U.S. coast by late this week, and the risk of direct
impacts continues to increase. However, given the uncertainty in
track and intensity forecasts at those time ranges, it's too soon to
determine the exact timing, location, and magnitude of those
impacts.

2. Interests along the U.S. East Coast, particularly from north
Florida through North Carolina, should closely monitor the progress
of Florence, ensure they have their hurricane plan in place, and
follow any advice given by local officials.

3. Large swells affecting Bermuda and portions of the U.S. East
Coast will continue this week. These swells will result in
life-threatening surf and rip currents.

FORECAST POSITIONS AND MAX WINDS

INIT 09/0900Z 24.5N 55.8W 60 KT 70 MPH
12H 09/1800Z 24.6N 56.7W 70 KT 80 MPH
24H 10/0600Z 24.8N 58.3W 85 KT 100 MPH
36H 10/1800Z 25.3N 60.4W 100 KT 115 MPH
48H 11/0600Z 26.1N 63.1W 110 KT 125 MPH
72H 12/0600Z 28.2N 69.1W 125 KT 145 MPH
96H 13/0600Z 31.3N 74.8W 120 KT 140 MPH
120H 14/0600Z 34.4N 77.9W 105 KT 120 MPH...INLAND

$$
Forecaster Brown

[Nimbus]

The forecast position for today at 1800Z doesn't gain much latitude.
This morning the convection with lower shear is increasing so we will have to wait for a recon fix.
Really hard to fix a center based on possibly sheared convection but assuming the shear has ended the center might be near 24.3 N.

There are several weak cyclonic upper level circulations to the west of Florence which haven't filled yet so no sign of the monster ridge over Bermuda.

Longer term the ridging over Arkansas is getting squeezed to the east a little, that would have to retrograde back west again later in the forecast.

[GCANE]

Moving into much better upper tropospheric conditions.
Should allow vort column to expand vertically and angular momentum to increase.

[bob rulz]

Any recent microwave passes? Hard to tell the internal structure without it right now.

[Hurricane Andrew]

Still looks...a little messy. I wonder how much the reorganization delay might bring down her peak strength. Promets?

[HurricaneIrma]

the apparent wsw motion is becoming more prevalent with every image..

may drop below 24N by morning unless it levels out.

Do that mean the track will shift back west over South Carolina?

[hurricaneCW]

Very likely she'll be back up to a hurricane by the next advisory.

RI could begin late tonight.

[GCANE]

Consistently firing cold-cloud top cell firing just east of the CoC

[sittingduck]

the apparent wsw motion is becoming more prevalent with every image..

may drop below 24N by morning unless it levels out.

Do that mean the track will shift back west over South Carolina?

South Carolina is still in the cone so it easily could go there. Pay attention to the NHC and the whole cone not just the line or dots.

[Kazmit]

I think this has been asked before but why does the NHC weaken Florence before making landfall? Eyewall replacement cycle?

[GCANE]

Feeder band on the SE quad has been firing off.
Pretty much pinching off any dry-air intrusion.

[KWT]

Very likely she'll be back up to a hurricane by the next advisory.

RI could begin late tonight.

I suspect 65kts is quite likely, given the convective ball has hung around a while. I'd like to see the microwave presentation as that would be pretty telling. Once the inner structure is sorted it will shoot off I think.

The only slight caveat is the convection isn't that impressive in terms of depth for a storm at 25N.