2021 Global Model Runs Discussion (Out thru day 16)

[cycloneye]

Is the 94L thread locked?

Is open.
viewtopic.php?f=59&t=122258&p=2941650#p2941650

[cycloneye]

Teleconnection on full gear.

 https://twitter.com/webberweather/status/1436737433509380099

[aspen]

As noted a few weeks ago, the GFS is having a lot of difficulty developing anything in the MDR compared to the west Atlantic, or at the very least being consistent about it. It has developed 94L and the Bahamas systems for the last few runs, but has been flip-flopping with the 0/20 AOI.

[Kohlecane]

As noted a few weeks ago, the GFS is having a lot of difficulty developing anything in the MDR compared to the west Atlantic, or at the very least being consistent about it. It has developed 94L and the Bahamas systems for the last few runs, but has been flip-flopping with the 0/20 AOI.

yeah my thoughts exactly, ensembles with be our friend it seems for MDR/CV atm although we will see how the Euro OP does

[otowntiger]

So I’m guessing, without even looking that the models have backed off of the development of the African waves based on the fact this thread is so dead, lol.

[Teban54]

So I’m guessing, without even looking that the models have backed off of the development of the African waves based on the fact this thread is so dead, lol.

The low rider wave is in its own thread with decent model support (except GFS).

Some EPS members hint at another TC from the wave behind the low rider, but it's in la la land and at this moment it seems to quickly recurve, so understandably it's not getting enough interest yet.

[toad strangler]

So I’m guessing, without even looking that the models have backed off of the development of the African waves based on the fact this thread is so dead, lol.

Wow, lazy dude lol

[sma10]

Wait, according to you This season was going to underperform yet we have had 3 majors already. Enough with the down casting it’s really tiring and getting old frankly,

And let's not forget the famous "given the lack of CV threats, it looks extremely unlikely the CONUS will be threatened by a Major" prediction.

And then Ida struck 5 days later.

I consider “CV” systems to be cyclones that become depressions or stronger while over the MDR. Technically, Ida was not a classic CV-type system, per definition.

Ida was not a CV system, and that was exactly my point.

Since you were of the belief that the US was highly unlikely to be hit by a CV system this season, you made a very broad (and incorrect) generalized statement that the US was basically protected from being hit by a major, completely disregarding the very real threat of non-CV systems

[Shell Mound]

And let's not forget the famous "given the lack of CV threats, it looks extremely unlikely the CONUS will be threatened by a Major" prediction.

And then Ida struck 5 days later.

I consider “CV” systems to be cyclones that become depressions or stronger while over the MDR. Technically, Ida was not a classic CV-type system, per definition.

Ida was not a CV system, and that was exactly my point.

Since you were of the belief that the US was highly unlikely to be hit by a CV system this season, you made a very broad (and incorrect) generalized statement that the US was basically protected from being hit by a major, completely disregarding the very real threat of non-CV systems

If I recall correctly, I stated that most Category-4+ landfalls on the CONUS are associated with CV-type systems, so I assumed that the U.S. would be more likely to escape Category-4+ impacts in 2021, owing to the projected absence of landfalls associated with CV-type systems. Obviously, I was incorrect, and Ida ended up being one of the costliest storms in American history. Ironically, a -AMO cycle may make cases such as Ida’s more likely, as a higher proportion of the Category-4+ impacts that do occur would be more likely to be associated with non-CV systems during a long-term -AMO cycle, given that the MDR tends to produce more long-tracking majors during a +AMO than a -AMO. However, climatologically speaking, I did note that most Category-4+ impacts on the CONUS since 1851 were associated with CV-type systems, though obviously this did not render “homegrown” Category-4+ impacts impossible.

[toad strangler]

I consider “CV” systems to be cyclones that become depressions or stronger while over the MDR. Technically, Ida was not a classic CV-type system, per definition.

Ida was not a CV system, and that was exactly my point.

Since you were of the belief that the US was highly unlikely to be hit by a CV system this season, you made a very broad (and incorrect) generalized statement that the US was basically protected from being hit by a major, completely disregarding the very real threat of non-CV systems

If I recall correctly, I stated that most Category-4+ landfalls on the CONUS are associated with CV-type systems, so I assumed that the U.S. would be more likely to escape Category-4+ impacts in 2021, owing to the projected absence of landfalls associated with CV-type systems. Obviously, I was incorrect, and Ida ended up being one of the costliest storms in American history. Ironically, a -AMO cycle may make cases such as Ida’s more likely, as a higher proportion of the Category-4+ impacts that do occur would be more likely to be associated with non-CV systems during a long-term -AMO cycle, given that the MDR tends to produce more long-tracking majors during a +AMO than a -AMO. However, climatologically speaking, I did note that most Category-4+ impacts on the CONUS since 1851 were associated with CV-type systems, though obviously this did not render “homegrown” Category-4+ impacts impossible.

You hedged climo was bulletproof and lost.

[Blown Away]

12z EURO decent shift N days 7-10 and looks like whatever develops will stay well N of Caribbean and be far enough N to miss CONUS and take a Larry type track.

[LarryWx]

12z EURO decent shift N days 7-10 and looks like whatever develops will stay well N of Caribbean and be far enough N to miss CONUS and take a Larry type track.

Imo, the difference is that with Larry it was a pretty easy call for a well OTS recurve due to the unanimous prog for a strong NE US trough vs with this one where there is no strong trough progged at least yet.

[sma10]

12z EURO decent shift N days 7-10 and looks like whatever develops will stay well N of Caribbean and be far enough N to miss CONUS and take a Larry type track.

Imo, the difference is that with Larry it was a pretty easy call for a well OTS recurve due to the unanimous prog for a strong NE US trough vs with this one where there is no strong trough progged at least yet.

Also Larry, isn't the 12z OP quite a bit further north than the ensembles?

[sma10]

Ida was not a CV system, and that was exactly my point.

Since you were of the belief that the US was highly unlikely to be hit by a CV system this season, you made a very broad (and incorrect) generalized statement that the US was basically protected from being hit by a major, completely disregarding the very real threat of non-CV systems

If I recall correctly, I stated that most Category-4+ landfalls on the CONUS are associated with CV-type systems, so I assumed that the U.S. would be more likely to escape Category-4+ impacts in 2021, owing to the projected absence of landfalls associated with CV-type systems. Obviously, I was incorrect, and Ida ended up being one of the costliest storms in American history. Ironically, a -AMO cycle may make cases such as Ida’s more likely, as a higher proportion of the Category-4+ impacts that do occur would be more likely to be associated with non-CV systems during a long-term -AMO cycle, given that the MDR tends to produce more long-tracking majors during a +AMO than a -AMO. However, climatologically speaking, I did note that most Category-4+ impacts on the CONUS since 1851 were associated with CV-type systems, though obviously this did not render “homegrown” Category-4+ impacts impossible.

You hedged climo was bulletproof and lost.

Also, what are the actual stats on Cat 4+ US landfalls? Are "most" CV systems? Camille, Michael, Ida and Labor Day weren't. Andrew was (per se) but was a relative non entity until approach to the Bahamas. Frankly, homegrown seems proportionally a greater risk then long-trackers

[LarryWx]

12z EURO decent shift N days 7-10 and looks like whatever develops will stay well N of Caribbean and be far enough N to miss CONUS and take a Larry type track.

Imo, the difference is that with Larry it was a pretty easy call for a well OTS recurve due to the unanimous prog for a strong NE US trough vs with this one where there is no strong trough progged at least yet.

Also Larry, isn't the 12z OP quite a bit further north than the ensembles?

Yes although even with that most of the 12Z EPS members still did recurve well east of the CONUS.

Regardless of what the 12Z Euro/EPS showed, there are lots of moving parts and we’re speculating about something two weeks out in this complex setup. You’d probably just about have to favor a recurve east of the CONUS but that’s about all one can say right now as there’s too much uncertainty with the many moving parts (93L, possible Bahamas low, abd the Typhoon among other things) plus the very warm western Atlantic and La Niña both favoring a stubborn WAR.

[Shell Mound]

If I recall correctly, I stated that most Category-4+ landfalls on the CONUS are associated with CV-type systems, so I assumed that the U.S. would be more likely to escape Category-4+ impacts in 2021, owing to the projected absence of landfalls associated with CV-type systems. Obviously, I was incorrect, and Ida ended up being one of the costliest storms in American history. Ironically, a -AMO cycle may make cases such as Ida’s more likely, as a higher proportion of the Category-4+ impacts that do occur would be more likely to be associated with non-CV systems during a long-term -AMO cycle, given that the MDR tends to produce more long-tracking majors during a +AMO than a -AMO. However, climatologically speaking, I did note that most Category-4+ impacts on the CONUS since 1851 were associated with CV-type systems, though obviously this did not render “homegrown” Category-4+ impacts impossible.

You hedged climo was bulletproof and lost.

Also, what are the actual stats on Cat 4+ US landfalls? Are "most" CV systems? Camille, Michael, Ida and Labor Day weren't. Andrew was (per se) but was a relative non entity until approach to the Bahamas. Frankly, homegrown seems proportionally a greater risk then long-trackers

Since 1851, thirty-one tropical cyclones have made landfall on the CONUS as Category 4s or stronger, including this year’s Ida. Of these, nineteen (~61%), or somewhat fewer than two-thirds of the total, became depressions or stronger while in the MDR. These were Storm #5 (1886), Storm #7 (1898), Storm #1 (1900), Storm #2 (1915), Storm #6 (1916), Storm #7 (1926), Storm #4 (1928), Storm #9 (1945), Storm #4 (1947), Storm #2 (1949), Hazel (1954), Donna (1960), Betsy (1965), Hugo (1989), Andrew (1992), Charley (2004), Harvey (2017), Irma (2017), and Laura (2020). So a majority of Category-4+ landfalls on the CONUS are indeed associated with CV-type systems that became depressions or stronger while in the MDR. However, more than a third of the total were associated with non-CV systems that originated outside the MDR, including the four examples that you mentioned.

[SteveM]

If I recall correctly, I stated that most Category-4+ landfalls on the CONUS are associated with CV-type systems, so I assumed that the U.S. would be more likely to escape Category-4+ impacts in 2021, owing to the projected absence of landfalls associated with CV-type systems. Obviously, I was incorrect, and Ida ended up being one of the costliest storms in American history. Ironically, a -AMO cycle may make cases such as Ida’s more likely, as a higher proportion of the Category-4+ impacts that do occur would be more likely to be associated with non-CV systems during a long-term -AMO cycle, given that the MDR tends to produce more long-tracking majors during a +AMO than a -AMO. However, climatologically speaking, I did note that most Category-4+ impacts on the CONUS since 1851 were associated with CV-type systems, though obviously this did not render “homegrown” Category-4+ impacts impossible.

Proportionally more cases like Ida does not mean that cases like Ida 'become more likely'.

[Shell Mound]

If I recall correctly, I stated that most Category-4+ landfalls on the CONUS are associated with CV-type systems, so I assumed that the U.S. would be more likely to escape Category-4+ impacts in 2021, owing to the projected absence of landfalls associated with CV-type systems. Obviously, I was incorrect, and Ida ended up being one of the costliest storms in American history. Ironically, a -AMO cycle may make cases such as Ida’s more likely, as a higher proportion of the Category-4+ impacts that do occur would be more likely to be associated with non-CV systems during a long-term -AMO cycle, given that the MDR tends to produce more long-tracking majors during a +AMO than a -AMO. However, climatologically speaking, I did note that most Category-4+ impacts on the CONUS since 1851 were associated with CV-type systems, though obviously this did not render “homegrown” Category-4+ impacts impossible.

Proportionally more cases like Ida does not mean that cases like Ida 'become more likely'.

By “more likely,” I meant that cases like Ida’s would form a higher proportion of all Category-4+ impacts on the CONUS, relative to those of CV origin.

[Spacecoast]

FWIW, here is the NASA 10-day model.

I understand (from others) that it is not very reliable compared to others.
But I do like their visualizations, and graphics..
0z NASA / GMAO:

[StPeteMike]

16z GFS has the wave expected to come off Africa Late Monday/Early Tuesday on a due west course heading towards the islands. Don’t think it’s impossible if it keeps south enough and avoids any weakness in the ridge. Will be something to watch.