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Tropical Major Hurricane Florence

snowlover91 said:
The GEFS has a few members near the East Coast but most take it OTS with Bermuda as the biggest threat for impacts.
06L_gefs_latest.png


Interestingly the latest visibles show a possible eye clearing out. The FV3 also takes this perilously close to the US so we still need to watch it. Small changes in the blocking and this may not go OTS like currently modeled.
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It appears to me that based on the last few ensemble runs of various models, the more it weakens the next few days, the less confidence for OTS. The smaller, weaker members seem to be the ones at most risk for going back west enough to hit the US. So, for those who don't want it near the US, root for less weakening as this week goes forward.
Based on climo, alone, the smart bet is easily an OTS bet.
 
12z GFS and the 0z Euro agree on OTS let's see if that can hold up with the 12z Euro

CMC does still get really close to the OBX before turning NNE
 
Last 4 GEFS runs with regard to TS+ hits on the US SE coast out of ~20 members:
18Z Mon 0 hits
0Z Tue 0 hits
6Z Tue 4 hits: FL/GA border, SC/NC border, NC OB, skirt NC OB
12Z Tue 2 hits: GA/SC border, SC

So, low risk remains, but odds still much better to stay away.
 
Last edited:
GaWx said:
Last 4 GEFS runs with regard to TS+ hits on the US SE coast out of ~20 members:
18Z Mon 0 hits
0Z Tue 0 hits
6Z Tue 4 hits: FL/GA border, SC/NC border, NC OB, skirt NC OB
12Z Tue 2 hits: GA/SC border, SC

So, low risk remains, but odds still much better to stay away.
Click to expand...

Agreed, climo and the main models like GFS, Euro and FV3 also take this OTS. CMC is an outlier at this point and not likely to occur IMO. Interestingly the GFS was superior with depicting Lane as a threat to Hawaii in the long range while the consensus of other models like Euro, CMC, UK and others all kept Lane too weak and far south. GFS has been doing fairly well lately with intensity and track in the PAC and here with Florence it appears to be leading the way as well.
 
snowlover91 said:
Agreed, climo and the main models like GFS, Euro and FV3 also take this OTS. CMC is an outlier at this point and not likely to occur IMO. Interestingly the GFS was superior with depicting Lane as a threat to Hawaii in the long range while the consensus of other models like Euro, CMC, UK and others all kept Lane too weak and far south. GFS has been doing fairly well lately with intensity and track in the PAC and here with Florence it appears to be leading the way as well.
Click to expand...

Good points.
12Z Euro is for the 2nd time in a row OTS and misses Bermuda to the east though it is a little closer to Bermuda.
 
178
WTNT61 KNHC 041846
TCUAT1

Hurricane Florence Tropical Cyclone Update
NWS National Hurricane Center Miami FL AL062018
250 PM AST Tue Sep 04 2018

...FLORENCE CONTINUING TO STRENGTHEN...

Recent satellite imagery indicates that Florence has continued to
intensify during the past few hours, and maximum sustained winds
have increased to 85 mph (140 km/h). This increase in intensity
will be reflected in the forecast issued with the 500 PM AST (2100
UTC) advisory package.


SUMMARY OF 250 PM AST...1850 UTC...INFORMATION
---------------------------------------------------
LOCATION...20.0N 42.7W
ABOUT 1265 MI...2035 KM ENE OF THE LESSER ANTILLES
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...984 MB...29.06 INCHES

$$
Forecaster Brennan/Berg
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EPS has a relative tight cluster at day 5.

eps_mslp_lows_atlantic_120.png


then at day 8 its another story. Still think it's going to recurve but interesting.

eps_mslp_lows_atlantic_192.png
 
Kylo said:
EPS has a relative tight cluster at day 5.

eps_mslp_lows_atlantic_120.png


then at day 8 its another story. Still think it's going to recurve but interesting.

eps_mslp_lows_atlantic_192.png
Click to expand...
That's just enough spread, almost 2 camps, to make me put away my pen I was going to use to write off Florence.

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A further update on the 12Z EPS. Main message: still way too soon for all clear for SE US.

The crucial longitude point is near 60W and the crucial day is ~ Sunday 9/9. That's when ~2/3 of the 51 members, the ones north of 30N, then recurve safely into the north Atlantic. However, ~1/3 of them, which are then located 25-30N and which average somewhat weaker than the recurvers further to the north, stop their northward move and turn left/west due to being trapped by a ridge. Then whereas a few just mill around, the majority of that 1/3 become SE US threats with a whopping 9 TS+ members hitting (almost all Hs), the most of any recent run. Also, there are 2 other members with Hs not far offshore NC at the end of the run. Most (6) of these 9 hits are earlier, 9/12-14: 4 hit near SC/NC border and the other 2 hit near Daytona Beach. However, 3 of them are much later (yes they are from Florence, not the followup which itself hits FL with Hs from 3 members) 9/18-9: 2 hit SC and 1 hits S FL. In addition, one of the earlier 6 H hits comes back offshore and then re-hits the SE with a H on 9/17 at the FL/GA border.
 
metwannabe said:
That's just enough spread, almost 2 camps, to make me put away my pen I was going to use to write off Florence.

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Yep, that's what I was thinking too. Majority still recurve. The system behind it in the NE Caribbean has a chance to get interesting down the road too.

eps_mslp_lows_atlantic_240.png
 
First time checking UK ensembles but bulk of members are staying south of 30N before crossing 60W. I remember last year for Irma the UK did a good job of modeling it, it was the first model to pickup on Irma scraping Cuba and heading towards western FL.Screen Shot 2018-09-04 at 4.33.15 PM.png
 
158
WTNT31 KNHC 042031
TCPAT1

BULLETIN
Hurricane Florence Advisory Number 22
NWS National Hurricane Center Miami FL AL062018
500 PM AST Tue Sep 04 2018

...FLORENCE STRONGER THAN ANTICIPATED...
...STILL NO THREAT TO LAND THROUGH THE WEEKEND...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...20.3N 43.2W
ABOUT 1305 MI...2100 KM E OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...984 MB...29.06 INCHES


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


DISCUSSION AND OUTLOOK
----------------------
At 500 PM AST (2100 UTC), the center of Hurricane Florence was
located near latitude 20.3 North, longitude 43.2 West. Florence is
moving toward the west-northwest near 12 mph (19 km/h), and this
general motion is expected to continue through Wednesday night. A
northwestward motion is expected to begin by Thursday with
Florence's forward speed decreasing by the weekend.

Maximum sustained winds have increased to near 85 mph (140 km/h)
with higher gusts. Some additional strengthening is possible
through tonight, but Florence is expected to weaken beginning on
Wednesday and continuing through Friday.

Hurricane-force winds extend outward up to 15 miles (30 km) from the
center, and tropical-storm-force winds extend outward up to 105
miles (165 km).

The estimated minimum central pressure is 984 mb (29.06 inches).


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


NEXT ADVISORY
-------------
Next complete advisory at 1100 PM AST.

$$
Forecaster Berg
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669
WTNT41 KNHC 042032
TCDAT1

Hurricane Florence Discussion Number 22
NWS National Hurricane Center Miami FL AL062018
500 PM AST Tue Sep 04 2018

Despite being over marginally warm water and in an environment of
moderate west-southwesterly shear, Florence's intensity has
increased during the day. The hurricane has a cloud-filled eye in
visible imagery, and the central dense overcast is becoming more
symmetric. Based on Dvorak estimates of T4.5 from TAFB and SAB,
and a SATCON estimate of 77 kt, the initial intensity is now,
somewhat surprisingly, 75 kt. Since the current intensification
trend may not be over, the official forecast calls for Florence to
strengthen just a little more during the next 6-12 hours. Even
though the hurricane will be moving over progressively warmer
waters, increasing vertical shear and dry air in the middle levels
of the atmosphere should induce some weakening in the 24-72 hour
time frame. Lower shear after 72 hours will likely allow Florence
to regain hurricane strength by the end of the forecast period.
The NHC intensity forecast is primarily adjusted to account for the
recent strengthening trend, and is closest to the Florida State
Superensemble and HCCA guidance.

Florence remains on a west-northwestward course at 300/10 kt. This
trajectory is expected to continue through 36 hours while the
hurricane remains near the southwestern edge of the subtropical
ridge. After 36 hours, Florence is expected to turn northwestward
and slow down as it enters a break in the ridge. The track models
are in good agreement and show little spread through 48 hours. On
days 3-5, the biggest outlier is the UKMET, which lies to the south
of the guidance suite. In fact, the bulk of the models, including
the deterministic GFS and ECMWF, are all now showing a more
definitive poleward motion by day 5. While the official NHC track
forecast reflects this thinking, there is still considerable spread
among the associated global model ensembles, and the longer-term
forecast should be considered low confidence.

FORECAST POSITIONS AND MAX WINDS

INIT 04/2100Z 20.3N 43.2W 75 KT 85 MPH
12H 05/0600Z 21.0N 44.8W 80 KT 90 MPH
24H 05/1800Z 22.1N 46.8W 75 KT 85 MPH
36H 06/0600Z 23.2N 48.7W 65 KT 75 MPH
48H 06/1800Z 24.3N 50.4W 60 KT 70 MPH
72H 07/1800Z 26.0N 53.0W 55 KT 65 MPH
96H 08/1800Z 27.5N 55.0W 60 KT 70 MPH
120H 09/1800Z 29.5N 56.5W 70 KT 80 MPH

$$
Forecaster Berg
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Kylo said:
First time checking UK ensembles but bulk of members are staying south of 30N before crossing 60W. I remember last year for Irma the UK did a good job of modeling it, it was the first model to pickup on Irma scraping Cuba and heading towards western FL.View attachment 5833
Click to expand...

Rut row Raggy


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Usually the ones that hit NC stay well north of the Caribbean islands.


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