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2021 Atlantic Hurricane Season Tracking Thread


WxWatcher007
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20 hours ago, MN Transplant said:

Sam is now the #1 ACE system in the 2021 Atlantic season

You got that right.  Thank goodness for that track.  Bermuda is quite hardened against storms but this would be far worse than Fabian!  And if this steamed NW towards Delmarva, well it would be quite serious easily the worst tropical for this area for most of us in our lifetimes.

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50 minutes ago, Stormfly said:

You got that right.  Thank goodness for that track.  Bermuda is quite hardened against storms but this would be far worse than Fabian!  And if this steamed NW towards Delmarva, well it would be quite serious easily the worst tropical for this area for most of us in our lifetimes.

Longest lived major in the Atlantic since 2017. Very impressive.

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Atlantic Basin Update--10/1/21

Recap
August was a busy month, with numerous US landfalls.

September, however, was a month of contradictions. It was quieter in the landfall department, but we had Hurricane Larry make landfall in Atlantic Canada, Hurricane Nicholas make landfall in Texas, and Tropical Storm Mindy make landfall in Florida. 

We saw a lot of slop--with 9 named storms this season that lasted 2 days or less, the most since 2007. We also saw Major Hurricane Sam, which is only the 8th hurricane since 1966 to last more than one week at major hurricane strength according to Phil Klotzbach at CSU.

Unfortunately, part of my forecast for the peak season between Aug 20 and Oct 20 is going to be a bust, with the number of named storms fully decoupling from my hurricane and major hurricane prediction. With Victor failing to reach hurricane status, that really locks up that fail. :axe: 

Peak Season Forecast (Actual)
Named Storms:  13 (12)
Hurricanes: 9 (4) 
Major Hurricanes: 5 (3) 

iSKD6iz.jpg

Image courtesy of Philip Klotzback & CSU

Overview 
Tropical Storm Victor is likely to be the last Cape Verde (CV) system of the season. The MDR between the Antilles and coast of Africa, after struggling to develop positive SST anomalies during the early part of the season, warmed fairly dramatically during September, extending the traditional CV season through the end of September. That doesn't mean that we won't see more activity, as I expect strong waves to continue pushing through the region through the first two-thirds of October as the MJO remains favorable. 

t3F1QyV.gif

Now, climatology shifts quickly toward the homebrew region of the SW Atlantic and western Caribbean. 

XLROzXv.jpg

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Shear
Shear will be a critical factor in whether we see an active October. In a cool neutral ENSO, shear decreases in the Caribbean, and although shear looks strong currently, there does look to be a window approximately a week from now in the western Caribbean. The gif below shows 5-day anomaly averages, so a window can (and I think will) form in between this. In fact, looking at the daily numbers, the GEFS pops a window in the SW Atlantic and western Caribbean in approximately ten days. 

giphy.gif?cid=790b76113e39abeba495159208

TCHP/OHC
This area of the basin tends to be the warmest, and that's no different here. Although the depth of the heat is less than the outrageous 2020 season, the extent of the warmth is actually a little larger than 2020, particularly in the Gulf and along the SE coast. This heightens the risk for hurricanes and major hurricanes, provided disturbances can develop in a window of reduced shear. 

giphy.gif?cid=790b7611e838912f2dc56e0455

The western part of the basin will likely need to wait until the suppressed phase of the CCKW passes this week, but we're already starting to see a growing signal for development in the long range. 

Steering Pattern
Going back to my steering pattern discussion on September 11th, I didn't make the best call lol. The recurves continued, though Larry did find a way to make landfall in Atlantic Canada. The short lived Odette was shunted off the east coast while Sam has stayed well out to sea.

I think this is because we had too much activity in the basin. The ridging was there, but with so many weak systems and non-tropical lows/troughs weakening the central Atlantic ridge, anything developing in the basin has followed the weakness well out to sea. 

October gets complicated. On one hand, homebrew systems, especially in the western Caribbean, greatly increase landfall odds with so many landmasses nearby. On the other, October brings more fronts and troughs that become kickers for systems trying to move westward. The caveat to that, is the prevalence of cutoff lows we've seen so far.

As a result, I'm a bit gun shy on landfall chances in October, though I do not think the US is done at all with threats. That's normal.

The EPS and GEFS show ridging likely being dominant for the first two-thirds of the month, increasing chances of close calls off the SE coast or landfalls in the Caribbean, but we really need to see what the in-situ steering pattern is before having greater confidence in calling for anything higher than the climatological average of landfall IMO. 

4YGLZzc.png

Btd4a9R.png

Atlantic Areas of Interest
Currently, there is no specific disturbance to focus on. In fact, the NHC does not have a even a lemon in the basin for the first time in a while. I know the GFS is showing development, but just as I tell folks to be careful when there isn't a surface signal on the operational guidance, be careful of the GFS being overzealous in developing western Caribbean phantoms as well this time of year. Analyze the environment and look for the subtle signal.

There are two zones to watch.

1) Western Caribbean--This isn't a surprise as climo starts to favor it, but in the next 7-10 days we could see some development in the region as a tropical wave in the eastern Caribbean moves west and slows down. I'd lean toward the latter end of this 7-10 day range, as we see the suppressed stage of the CCKW/MJO. 

2) Western Atlantic--This is a more tricky signal to decipher, as I think it may be driven by what happens in the Caribbean. The guidance tries to sharpen some type of wave or disturbance next week, but while the GFS is slower and more aggressive off the SE coast, the Euro and others keep things broad and unable to develop. Worth watching casually, but a lower shot deal at this point. 

October is often the last hurrah for hurricane season. Happy hunting. 

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The mindset is quickly transitioning from tropical to winter, but as expected we’re starting to see a slightly stronger signal for activity as we get toward the 10th and onward.

A little low is trying to form off the SE but is getting sheared to hell currently. Could become some type of coastal off the Mid-Atlantic this weekend and the start of next week.

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Hmmm... LWX AFD from this afternoon:

The pattern for Saturday remains uncertain at this time as it will
be heavily dependent on a coastal low off the Carolina coast. Models
have differing solution with the GFS keeping a strong high pressure
/ upper ridge over the NE US which prevents the coastal low from
moving northward toward our region. On the other hand, the Euro is
weaker with the high and allows the low to bring areas of 1 to 2
inches of precipitation to parts of our region. General trends have
pushed precipitation to the late Saturday and into Sunday period
with areas around and below DC experiencing the heaviest
precipitation. The threat for flooding has increased especially if
the coastal low shifts closer to the coast with flooding most likely
to occur if the heaviest rain occurs over our metro areas. There is
the possibility that our region remains mostly dry this weekend
especially if the GFS solution comes true. Temperatures on Saturday
will be slightly cooler in the 70s with overnight lows in upper 50s
to lower 60s.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...

Come Sunday, guidance continues to diverge on how it handles an
upper level trough across the Eastern Seaboard. Guidance varies in
developing an upper level low and a coastal low along a surface
trough. The potential surface low is being monitored by the NHC for
potential tropical development off the SE US coast (see nhc.noaa.gov
for the latest). Regardless if this system officially becomes named
a tropical system, heavy rain and gusty winds are possible Sunday
mainly east of the Blue Ridge. Impacts are highly dependent on the
track of the surface low, and considerable uncertainty remains.
Regardless, if the low moves nearby, it should be out of the area by
Sunday night with dry weather returning early next week as upper
level ridging builds across the region.
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Both areas of interest have ended up being legit, as the western Caribbean had more favorable development conditions but the wave in question will end up developing in the Pacific.

Meanwhile, the slop off the east coast probably develops into a coastal low, even though it’ll likely be non-tropical. Too much shear in the SW Atlantic right now. 

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On 10/20/2021 at 11:07 PM, WxWatcher007 said:

Welp, time to shut it down. Forecast was a bust. We're on to winter. 

Grade: C

Peak Season Forecast (Actual)
Named Storms:  13 (11)
Hurricanes: 9 (4) 
Major Hurricanes: 5 (3) 

Im dropping  my grade to a  D. It was a ONE storm season. I got  some things wrong  but  so did the  super casters. It WASNT an east coast season and contrary to just about  every expert who said  it would  be  a  back ended super active  oct/nov it wasnt.

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10 hours ago, ldub23 said:

Im dropping  my grade to a  D. It was a ONE storm season. I got  some things wrong  but  so did the  super casters. It WASNT an east coast season and contrary to just about  every expert who said  it would  be  a  back ended super active  oct/nov it wasnt.

I have a question. What would be an A grade from you? Also calling that the season is dead every season all season means by random chance you will be right at some point and the super casters got a lot less wrong.

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4 hours ago, SnowenOutThere said:

I have a question. What would be an A grade from you? Also calling that the season is dead every season all season means by random chance you will be right at some point and the super casters got a lot less wrong.

I  have high standards. 2004/05 would be an A+++++. 2007 a C+. 1996/99 that  had  east  coast action a B+. 1985-A-.

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