ATL: FLORENCE - Post-Tropical - Discussion

[chaser1]

There's no doubt that the T.D. is presently tracking Westward and at a decent clip too. I was worried about this scenario possibly playing out a couple days ago while so many were grabbing their "fishing poles". Broad gyre slower to develop then anticipated and tracks further west compliments of the lower trades train. Near term tepid SST's and an upstream potential increase of cooler SST's and more hostile upper level conditions. Add to that recipe "Ridgezilla" potentially beckoning to reassert itself over the N.E. CONUS Seaboard with time and this really does give me an increasing concern of a potential Andrew scenario redux but this time the concern might mean a larger envelope storm potentially targeting the Mid-Atlantic region. If I'm living in the Carolina's, I'm rooting for "Florence to be" to go convective bonkers tonight and begin a WNW to NW motion ASAP.

[TheStormExpert]

This has yet to turn WNW and now is not forecasted to become a hurricane within the next 5-days. Could this eventually dissipate within the next 5-7 days?

[Hurricaneman]

This has yet to turn WNW and now is not forecasted to become a hurricane within the next 5-days. Could this eventually dissipate within the next 5-7 days?

No dissipation but being weaker when it gets to the fork in the road could mean the US mainland may have to keep a close eye on this even if it’s forecast to recurve as weaker usually = more west and in this case could cause it to miss the trough or only get partially picked up and shoved west

[AutoPenalti]

This has yet to turn WNW and now is not forecasted to become a hurricane within the next 5-days. Could this eventually dissipate within the next 5-7 days?

No dissipation but being weaker when it gets to the fork in the road could mean the US mainland may have to keep a close eye on this even if it’s forecast to recurve as weaker usually = more west and in this case could cause it to miss the trough or only get partially picked up and shoved west

GFS trending stronger 78 hrs out.

[cycloneye]

BULLETIN
Tropical Depression Six Intermediate Advisory Number 6A
NWS National Hurricane Center Miami FL AL062018
800 PM AST Fri Aug 31 2018

...TROPICAL DEPRESSION PASSING SOUTH OF THE CABO VERDE ISLANDS...
...RAINBANDS AND GUSTY WINDS AFFECTING THOSE ISLANDS...


SUMMARY OF 800 PM AST...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...14.0N 25.0W
ABOUT 65 MI...105 KM SSW OF BRAVA IN THE CABO VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES

[hipshot]

I am wondering why we don't see these Atlantic storms indicated on the map at the top of the screen. I see the Epac ones but none of the
Atlantic. Did something change?

[cycloneye]

I am wondering why we don't see these Atlantic storms indicated on the map at the top of the screen. I see the Epac ones but none of the
Atlantic. Did something change?

It has to be a glitch on the map.Hopefully is fixed very soon.

[tolakram]

I am wondering why we don't see these Atlantic storms indicated on the map at the top of the screen. I see the Epac ones but none of the
Atlantic. Did something change?

It has to be a glitch on the map.Hopefully is fixed very soon.

I'm not sure, I was hoping the declaration of a TD would fix it.

[cycloneye]

Still a TD on 00z Best Track.

AL, 06, 2018090100, , BEST, 0, 140N, 249W, 30, 1004, TD

[Hypercane_Kyle]

TD6 looking much healthier this evening:

[cycloneye]

Tropical Depression Six Discussion Number 7
NWS National Hurricane Center Miami FL AL062018
1100 PM AST Fri Aug 31 2018

Convection associated with the depression is becoming more
concentrated, although the center still appears to be near the
eastern edge of the convective mass. The latest satellite
intensity estimates from TAFB and SAB are 30 and 25 kt repsectively,
while the CIMSS satellite consensus method suggests the cyclone has
become a tropical storm. Based on the available data, the initial
intensity remains a possibly conservative 30 kt. The depression is
feeling the effects of moderate easterly vertical wind shear, with
little or no cirrus outflow in the eastern semicircle.

The initial motion is now 285/12. Deep layer easterly or east-
southeasterly flow on the south side of the subtropical ridge should
steer the cyclone generally west-northwestward across the open
Atlantic ocean for the next 3-4 days. After that time, the cyclone
is expected to turn northwestward toward a weakness in the
subtropical ridge. The track guidance remains in good agreement
with this scenario, although there remains some spread on how
sharp the turn will be near the end of the forecast period. The
new forecast track, which is an update of the previous forecast, is
near the various consensus models.

While the current shear is expected to subside during the next day
or so, the forecast track takes the cyclone over waters that cool
to near 26C in about 48 h. The intensity forecast thus calls for
only gradual intensification through this time. After 48-72 h, the
system should move over warmer water, but also should encounter
increasing westerly shear. The intensity guidance responds to this
combination of ingredients by showing little change in strength.
The new intensity forecast, which is unchanged from the previous
forecast, is in the stronger portion of the inetnsity guidance and
above the forecasts of the consensus models.


FORECAST POSITIONS AND MAX WINDS

INIT 01/0300Z 14.2N 25.5W 30 KT 35 MPH
12H 01/1200Z 14.7N 27.4W 35 KT 40 MPH
24H 02/0000Z 15.5N 29.9W 40 KT 45 MPH
36H 02/1200Z 16.3N 32.6W 45 KT 50 MPH
48H 03/0000Z 17.0N 35.2W 50 KT 60 MPH
72H 04/0000Z 18.5N 40.0W 55 KT 65 MPH
96H 05/0000Z 20.5N 44.5W 60 KT 70 MPH
120H 06/0000Z 23.0N 47.5W 55 KT 65 MPH

$$
Forecaster Beven

[chaser1]

Well, to these weary eyes this ststem is most certainly looking like a storm now. I have to guess that NHC is simply waiting for first visible Sat. to confirm.

[USTropics]

I believe they are upgrading to TS Florence:

Code: Select all

AL, 06, 2018090106, , BEST, 0, 143N, 261W, 35, 1003, TS

[galaxy401]

Perfect timing to kick off September too!

[drezee]

Hello Florence! Welcome to the party...I hope you like fish...unless the euro is right...

NWS National Hurricane Center Miami FL AL062018
500 AM AST Sat Sep 01 2018

...TROPICAL STORM FLORENCE FORMS JUST WEST OF THE CABO VERDE
ISLANDS.

[toad strangler]

Hello Florence! Welcome to the party...I hope you like fish...unless the euro is right...

NWS National Hurricane Center Miami FL AL062018
500 AM AST Sat Sep 01 2018

...TROPICAL STORM FLORENCE FORMS JUST WEST OF THE CABO VERDE
ISLANDS.

It is exceedingly difficult and really quite rare for storms that genesis this far E to hit CONUS.

[bamajammer4eva]

5AM discussion

The biggest change noted among the track models on this cycle
was a westward shift in the overall guidance envelope. The European
model, in particular, swung significantly to the left, showing a weaker
Florence not feeling the break in the ridge quite as much. I'd like to
see this trend continue before making a significant change to the
forecast, so for now the updated NHC track prediction is only nudged
westward. That said, the models appear to be trending away
from a definitive recurvature scenario.

[cycloneye]

Tropical Storm Florence Discussion Number 8
NWS National Hurricane Center Miami FL AL062018
500 AM AST Sat Sep 01 2018

A recent SSMIS microwave pass has revealed that the cyclone has
become much better organized with more pronounced convective
banding. Satellite intensity estimates are wide ranging, spanning
from T1.5/25 kt from SAB to T3.4/53 kt from the UW-CIMSS ADT. Since
the numbers overall have increased, and the structure has improved,
the initial intensity is raised to 35 kt, in closest agreement to
the TAFB estimate, but this could be conservative. This makes the
depression Tropical Storm Florence, the sixth named storm of the
season.

Florence is moving west-northwestward, or 285/12 kt, and should
maintain this motion for the next 48 hours while traveling along the
southern periphery of the subtropical ridge. After 48 hours, the
storm is expected to reach a break in the ridge, causing it to slow
down and turn northwestward by day 5. The biggest change noted
among the track models on this cycle was a westward shift in the
overall guidance envelope. The European model, in particular, swung
significantly to the left, showing a weaker Florence not feeling the
break in the ridge quite as much. I'd like to see this trend
continue before making a significant change to the forecast, so for
now the updated NHC track prediction is only nudged westward. That
said, the models appear to be trending away from a definitive
recurvature scenario.

The environment is mixed with positives and negatives for Florence's
strengthening. For the first 3 days, vertical shear over Florence
should be quite low, but the cyclone will also be moving through a
less-than-ideal thermodynamic environment with marginal sea surface
temperatures and decreasing mid-level moisture. After 3 days, the
thermodynamic environment should begin to improve, but then the
shear is forecast to strengthen. These conflicting signals point to
only gradual strengthening, and the suite of intensity models aren't
too far off from one another, nor from the previous NHC forecast.
For that reason, no significant changes were made in this forecast
package.

FORECAST POSITIONS AND MAX WINDS

INIT 01/0900Z 14.5N 26.7W 35 KT 40 MPH
12H 01/1800Z 15.0N 28.7W 40 KT 45 MPH
24H 02/0600Z 15.7N 31.2W 45 KT 50 MPH
36H 02/1800Z 16.4N 33.7W 50 KT 60 MPH
48H 03/0600Z 17.1N 36.3W 55 KT 65 MPH
72H 04/0600Z 18.7N 41.4W 60 KT 70 MPH
96H 05/0600Z 21.0N 45.5W 60 KT 70 MPH
120H 06/0600Z 23.5N 48.5W 55 KT 65 MPH

$$
Forecaster Berg

[Nimbus]

That said, the models appear to be trending away from a definitive recurvature scenario.

Saw the dry air but Florence has has more of a moisture envelope now, guess NHC feels slower development could mean more western track. I thought Florence might tend to draw moisture closer to the ITCZ for another day before moving WNW into the dryer environment.

[Kingarabian]

Would be very uncomfortable if Florence develops slower than forecast or unexpectedly weakens. The recurve window seems to be a short one.