2023 Atlantic Hurricane season

[Windspeed]

JB has said next season will double this  years  numbers with an ace well over  200

Sorry, but if you can find anyone who can forecast 200+ ACE accurately, they need to be working for NOAA. Period. Total BS.

[Ed, snow and hurricane fan]

End of month GFS ensembles look interesting Caribbean/maybe ECUSA.  Enough of a signal to show up on the means.

[olafminesaw]

A little home brew weenie bait

[Ed, snow and hurricane fan]

4 hours ago, olafminesaw said:

A little home brew weenie bait

30 knot storms on the ensemble aren't as interesting as the persistent (0, 6, 12Z) GFS ensembles suggesting a system that might not develop as quickly as its predecessors and pose a Cape Verde season in overtime threat to the E Caribbean (and SEUSA?)  Weenies can ween for days, GFS family have seemed decent in not being too overenthusiastic, except in the SW Caribbean where it has done that since probably AVN/MRF days

[StantonParkHoya]

Little low, maybe a TD? on the euro for GA/SC

[MattPetrulli]

3 minutes ago, StantonParkHoya said:

Little low, maybe a TD? on the euro for GA/SC

Our next system to watch

[WxWatcher007]

Yeah pretty solid homebrew/hybrid signal for next weekend off the SE coast.

[shaggy]

2 hours ago, WxWatcher007 said:

Yeah pretty solid homebrew/hybrid signal for next weekend off the SE coast.

Icon coming in the furthest east at 12 with a weak low with the strongest winds displaced far to the north. Certainly not a fully tropical look to it was 

[MattPetrulli]

12z

Also interaction with high pressure to the north may lead to a tight gradient and creating a larger wind field than normal. I think there's enough here to put out a spot at 8 PM.

[Ed, snow and hurricane fan]

1 hour ago, MattPetrulli said:

12z

Also interaction with high pressure to the north may lead to a tight gradient and creating a larger wind field than normal. I think there's enough here to put out a spot at 8 PM.

I like my isobars a little more circular.  Longer term, Euro and ensembles and op GFS suggest a fish from NHC 7 day orange, but enough W members on GFS ensembles to suggest a NE Caribbean/Bermuda threat.   Edit to Add: weaker Euro members aren't recurving although the mean at 240 hours looks like OTS

[GaWx]

6 hours ago, shaggy said:

Icon coming in the furthest east at 12 with a weak low with the strongest winds displaced far to the north. Certainly not a fully tropical look to it was 

Yeah, probably ST. The UKMET has a hybrid low form in the E GOM instead.

[shaggy]

35 minutes ago, GaWx said:

Yeah, probably ST. The UKMET has a hybrid low form in the E GOM instead.

In this situation the hybrid or ST will likely bring bigger impacts to larger areas of the coast versus a true TD/TS. Gfs has a decent area of gale force winds up the southeast coast far away from the center

[GaWx]

2 hours ago, shaggy said:

In this situation the hybrid or ST will likely bring bigger impacts to larger areas of the coast versus a true TD/TS. Gfs has a decent area of gale force winds up the southeast coast far away from the center

 This only quite vaguely resembles 1984 (Diana), which originated from the tail end energy on a rather strong cold front going offshore/nontropical which quickly became tropical. But 1984 was an extremely rare storm (100+ year storm?) and it occurred two weeks earlier during heart of the season. I don’t look for anything like that of course and this could easily turn out to be no big deal other than a good rainfall producer for some areas. However, in the extreme, this could be a STD/STS that becomes a TC (especially if it then moves NE offshore). Regardless, it is an interesting situation due to uncertainty.

Edit: late August of 1898 may have been somewhat similar to 1984 that also became a hurricane that came back into the SE coast.

 Neither 1898 nor 1984 was during El Niño by the way. I’ll look to see if I can find more. But those are two of the most extreme cases off the top of my head.
 

This is more or less a potential “ridge over troubled waters” setup where a rather strong surface high to the north provides lower level convergence to the south, which leads to lift and then the formation of a sfc low.

[shaggy]

2 hours ago, GaWx said:

 This only quite vaguely resembles 1984 (Diana), which originated from the tail end energy on a rather strong cold front going offshore/nontropical which quickly became tropical. But 1984 was an extremely rare storm (100+ year storm?) and it occurred two weeks earlier during heart of the season. I don’t look for anything like that of course and this could easily turn out to be no big deal other than a good rainfall producer for some areas. However, in the extreme, this could be a STD/STS that becomes a TC (especially if it then moves NE offshore). Regardless, it is an interesting situation due to uncertainty.

Edit: late August of 1898 may have been somewhat similar to 1984 that also became a hurricane that came back into the SE coast.

 Neither 1898 nor 1984 was during El Niño by the way. I’ll look to see if I can find more. But those are two of the most extreme cases off the top of my head.
 

This is more or less a potential “ridge over troubled waters” setup where a rather strong surface high to the north provides lower level convergence to the south, which leads to lift and then the formation of a sfc low.

I believe Gustav 2004 also quickly developed as it moved onshore SC. 

 

Nothing suggest anything similar here though

[GaWx]

42 minutes ago, shaggy said:

I believe Gustav 2004 also quickly developed as it moved onshore SC. 

 

Nothing suggest anything similar here though

Thank you. Indeed, Gaston (what you meant) of late August of 2004, in this case during a weak El Niño, joins Diana and late Aug of 1898 as a nontropical origin TC that then moved into the SE US as an H. Looking to see if I find more.

 Bob of 1991 was nontropical that hit the NE as a H. But I was looking for those that hit NC south.

[GaWx]

12 hours ago, GaWx said:

Thank you. Indeed, Gaston (what you meant) of late August of 2004, in this case during a weak El Niño, joins Diana and late Aug of 1898 as a nontropical origin TC that then moved into the SE US as an H. Looking to see if I find more.

 Bob of 1991 was nontropical that hit the NE as a H. But I was looking for those that hit NC south.

I found several more including Arthur of early July of 2014 with mesoscale complex origin in the GOM and Cindy of early July of 1959 (not El Niño), which formed from a nontropical low along a cold front off FL. So, for the SE so far: 

-Arthur 2014: early July developing weak Nino cat 2 into NC

-Gaston 2004: late Aug weak Niño cat 1 into SC

-Diana of 1984: early to mid Sep incoming Nina cat 2 into NC

-Cindy of 1959: early Jul neutral ENSO cat 1 into SC

-Yankee Hurricane of 1935: formed from nontropical low E of Bermuda Oct 30 that hit SE FL as a cat 2 H Nov 4th! Warm neutral ENSO

-Storm #5 of 1913: early Oct formed from nontropical low off NE US and hit SC as cat 1/developing Nino

-Storm #2 of 1898: late Aug cold neutral into GA cat 1

*Edited to add several more including Yankee Hurricane of 1935 (based on link below) and storm #5 of 1913

 So, a TC that is purely nontropical in origin has resulted in a landfalling H on the SE US coast ~every 18 years on average over the last 125 years. The strongest landfalls were the three cat 2 hits, Arthur of 2014, Diana of 1984, and the Yankee H of 1935. Landfalls: 3 SC, 2 NC, 1 GA, 1 FL

 My educated guess based on recollection is that TS landfalls on the SE coast from nontropical origins have occurred a good bit more often than the once/18 years of H landfalls. But that’s intuitive because it typically takes a good bit of time for transition to tropical and there often isn’t a lot of time over water with them developing close to home.

 Edit: I was able to confirm a much higher frequency of SE TS landfalls vs H landfalls from a non-tropical origin: 12 in 73 years or  ~1 every 6 years on average. So, chances of a nontropical originating TC landfalling on the SE US as a TS are ~3 times higher than that for a H:

2022: Colin

2021: Danny

2015: Ana

2007: Gabrielle

2002: Kyle

1981: Bret

1976: Dottie

1967: Doria

1965: #9

1962: #2

1960: Brenda

1952: #3

 

https://en.m.wikipedia.org/wiki/1935_Yankee_hurricane

[jconsor]

Regardless of whether the system off the SE US coast becomes subtropical, there is a substantial risk of heavy rainfall and flooding from eastern NC to the eastern mid-Atlantic and Long Island.
 

 

[jconsor]

11 hours ago, GaWx said:

I found several more including Arthur of early July of 2014 with mesoscale complex origin in the GOM and Cindy of early July of 1959 (not El Niño), which formed from a nontropical low along a cold front off FL. So, for the SE so far: 

-Arthur 2014: early July developing weak Nino cat 2 into NC

-Gaston 2004: late Aug weak Niño cat 1 into SC

-Diana of 1984: early to mid Sep incoming Nina cat 2 into NC

-Cindy of 1959: early Jul neutral ENSO cat 1 into SC

-Yankee Hurricane of 1935: formed from nontropical low E of Bermuda Oct 30 that hit SE FL as a cat 2 H Nov 4th! Warm neutral ENSO

-Storm #5 of 1913: early Oct formed from nontropical low off NE US and hit SC as cat 1/developing Nino

-Storm #2 of 1898: late Aug cold neutral into GA cat 1

*Edited to add several more including Yankee Hurricane of 1935 (based on link below) and storm #5 of 1913

 So, a TC that is purely nontropical in origin has resulted in a landfalling H on the SE US coast ~every 18 years on average over the last 125 years. The strongest landfalls were the three cat 2 hits, Arthur of 2014, Diana of 1984, and the Yankee H of 1935. Landfalls: 3 SC, 2 NC, 1 GA, 1 FL

 My educated guess based on recollection is that TS landfalls on the SE coast from nontropical origins have occurred a good bit more often than the once/18 years of H landfalls. But that’s intuitive because it typically takes a good bit of time for transition to tropical and there often isn’t a lot of time over water with them developing close to home.

 Edit: I was able to confirm a much higher frequency of SE TS landfalls vs H landfalls from a non-tropical origin: 13 in 73 years or  ~1 every 6 years on average. So, chances of a nontropical originating TC landfalling on the SE US as a TS are ~3 times higher than that for a H:

2022: Colin

2021: Danny

2015: Ana

2007: Gabrielle

2002: Kyle

1981: Bret

1976: Dottie

1967: Doria

1965: #9

1962: #2

1960: Brenda

1952: #3

 

https://en.m.wikipedia.org/wiki/1935_Yankee_hurricane

Very helpful summary of the historical context.   Thanks, Larry!   

I think your summary shows that given a few days (even as little as 36-48 hours) over water off the SE US coast, a system of non-tropical origins with a decent upper-level wind setup can become a hurricane.  Of course, the majority of such systems remain at tropical/subtropical storm strength.  

FYI today's 0Z run of the NASA GEOS-5 model is showing what looks to be a high-end TS or cat 1 hurricane, certainly a more consolidated system than the global models (GFS, GEM, ECMWF) are indicating.

https://fluid.nccs.nasa.gov/wxmaps

I believe the NASA GEOS-5 model is run at 7 km resolution.

[GaWx]

Thanks, Yaakov.

 To clarify for the readers, the stats I presented are only for those that actually made landfall on the SE US. So, they wouldn’t apply to any that go NE and stay offshore, which may increase the chance for a H vs those that hit the SE.

 Based on everything I’ve seen for the current setup along with my analysis of over seven decades of history, I predict that IF this were to ever transition to a TC and IF it then were to landfall on the SE US that it would landfall there as a TS. Also, if it were to landfall there, I predict either NC or SC with further N in SC favored over further S. This doesn’t look to me like a FL or GA landfall though nothing is certain because nothing is ever certain especially this far out.

[GaWx]

 I went ahead and created a new thread on this potential late week offshore SE US STC/TC here:

 

[NorthHillsWx]

FINALLY the MDR is showing signs or relaxing. Increasing shear values start in the next 8-10 days and models are mixed on development until then. It’s been a wild ride for an El Niño year and one of the most active MDR seasons in awhile (recency bias). Thankfully the El Niño steering was in place allowing all of the storms to recurve. I think our attention rightfully turns to the NW Caribbean/homegrown scenarios for the rest of the season.

[jconsor]

I know most of our collective attention is on the potential subtropical system off the SE US coast.  However, I think the system in the E. Atlantic (currently given a 70% chance of developing by NHC) is worth watching carefully, since down the road in 7-10 days it has a decent opportunity to reach the Caribbean or western Atlantic.

This is a sneaky wave which will likely not develop in the next 3-4 days, but instead continue heading west under a strong ridge.  We're dealing with two waves that will likely merge here - firstly the one outlooked by NHC that just came off the African coast, and secondly a low-latitude ITCZ wave currently around 40W.  The two systems should combine by late Fri-early Sat into a broad wave.  This would initially slow development, due to its large size and lack of concentrated vorticity.

This system likely will find better upper level conditions (strong diffluence aloft, deeper moisture) once it passes 40W and clears the strong UL trough in the east Atlantic, and especially as it nears 60W and the Leeward/Windward islands.  With a much stronger than usual ridge for this time of year over the central Atlantic, there is a decent chance this system makes it into the eastern and northern Caribbean or heads slightly N of the Caribbean to near the Bahamas.

 

[GaWx]

27 minutes ago, jconsor said:

I know most of our collective attention is on the potential subtropical system off the SE US coast.  However, I think the system in the E. Atlantic (currently given a 70% chance of developing by NHC) is worth watching carefully, since down the road in 7-10 days it has a decent opportunity to reach the Caribbean or western Atlantic.

This is a sneaky wave which will likely not develop in the next 3-4 days, but instead continue heading west under a strong ridge.  We're dealing with two waves that will likely merge here - firstly the one outlooked by NHC that just came off the African coast, and secondly a low-latitude ITCZ wave currently around 40W.  The two systems should combine by late Fri-early Sat into a broad wave.  This would initially slow development, due to its large size and lack of concentrated vorticity.

This system likely will find better upper level conditions (strong diffluence aloft, deeper moisture) once it passes 40W and clears the strong UL trough in the east Atlantic, and especially as it nears 60W and the Leeward/Windward islands.  With a much stronger than usual ridge for this time of year over the central Atlantic, there is a decent chance this system makes it into the eastern and northern Caribbean or heads slightly N of the Caribbean to near the Bahamas.

 

12Z UKMET had this (0Z is further down in this post):

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER  54 HOURS
              FORECAST POSITION AT T+ 54 : 14.5N  27.2W

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    0000UTC 22.09.2023   60  14.5N  29.0W     1008            31
    1200UTC 22.09.2023   72  15.0N  32.2W     1007            32
    0000UTC 23.09.2023   84  15.3N  34.9W     1006            36
    1200UTC 23.09.2023   96  15.8N  37.9W     1005            38
    0000UTC 24.09.2023  108  16.3N  39.9W     1005            37
    1200UTC 24.09.2023  120  16.7N  42.4W     1004            44
    0000UTC 25.09.2023  132  17.4N  44.3W     1003            47
    1200UTC 25.09.2023  144  17.3N  46.7W     1003            48
    0000UTC 26.09.2023  156  17.2N  48.9W     1003            47
    1200UTC 26.09.2023  168  17.1N  49.9W     1001            60

———————

0Z UKMET: At 168 hours TS moving W at 15 mph 300 mi NE of Leewards

 

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER  60 HOURS
              FORECAST POSITION AT T+ 60 : 15.0N  33.7W

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    1200UTC 22.09.2023   60  15.0N  33.7W     1009            30
    0000UTC 23.09.2023   72  15.6N  36.3W     1008            30
    1200UTC 23.09.2023   84  16.0N  39.3W     1008            31
    0000UTC 24.09.2023   96  16.3N  41.7W     1008            30
    1200UTC 24.09.2023  108  16.4N  43.6W     1007            37
    0000UTC 25.09.2023  120  17.2N  46.4W     1007            36
    1200UTC 25.09.2023  132  17.8N  49.2W     1008            37
    0000UTC 26.09.2023  144  18.3N  52.1W     1008            42
    1200UTC 26.09.2023  156  18.6N  55.5W     1007            42
    0000UTC 27.09.2023  168  18.4N  58.2W     1005            37

[GaWx]

 I’ve found only three storms on record since the late 1800s that have formed in the MDR  E of 50W Sep 20+ and hit the CONUS:

1) 2002’s Lili: TD formed 9/21 near 45W and hit LA 10/3 as a H; El Nino 

2) 1966’s Inez: TD formed 9/21 near 35W and hit FL Keys 10/4 as a H; not El Niño

3) 1893’s storm #9 formed 9/25 near 25W and hit Carolinas 10/13 as a MH; not El Nino

[Normandy]

On 9/19/2023 at 5:23 AM, NorthHillsWx said:

FINALLY the MDR is showing signs or relaxing. Increasing shear values start in the next 8-10 days and models are mixed on development until then. It’s been a wild ride for an El Niño year and one of the most active MDR seasons in awhile (recency bias). Thankfully the El Niño steering was in place allowing all of the storms to recurve. I think our attention rightfully turns to the NW Caribbean/homegrown scenarios for the rest of the season.

Not sure what you are seeing.  We have a major hurricane threat for the islands In next 8 days with an additional system behind it in the GFS.  There are no signs of the MDR shutting down until early to mid October.  People have gotta let the El Niño go lol it has lost.  Clearly something else is going on that is allowing the basin to produce in an epic fashion despite this El Niño.

[GaWx]

7 hours ago, GaWx said:

12Z UKMET had this (0Z is further down in this post):

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER  54 HOURS
              FORECAST POSITION AT T+ 54 : 14.5N  27.2W

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    0000UTC 22.09.2023   60  14.5N  29.0W     1008            31
    1200UTC 22.09.2023   72  15.0N  32.2W     1007            32
    0000UTC 23.09.2023   84  15.3N  34.9W     1006            36
    1200UTC 23.09.2023   96  15.8N  37.9W     1005            38
    0000UTC 24.09.2023  108  16.3N  39.9W     1005            37
    1200UTC 24.09.2023  120  16.7N  42.4W     1004            44
    0000UTC 25.09.2023  132  17.4N  44.3W     1003            47
    1200UTC 25.09.2023  144  17.3N  46.7W     1003            48
    0000UTC 26.09.2023  156  17.2N  48.9W     1003            47
    1200UTC 26.09.2023  168  17.1N  49.9W     1001            60

———————

0Z UKMET: At 168 hours TS moving W at 15 mph 300 mi NE of Leewards

 

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER  60 HOURS
              FORECAST POSITION AT T+ 60 : 15.0N  33.7W

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    1200UTC 22.09.2023   60  15.0N  33.7W     1009            30
    0000UTC 23.09.2023   72  15.6N  36.3W     1008            30
    1200UTC 23.09.2023   84  16.0N  39.3W     1008            31
    0000UTC 24.09.2023   96  16.3N  41.7W     1008            30
    1200UTC 24.09.2023  108  16.4N  43.6W     1007            37
    0000UTC 25.09.2023  120  17.2N  46.4W     1007            36
    1200UTC 25.09.2023  132  17.8N  49.2W     1008            37
    0000UTC 26.09.2023  144  18.3N  52.1W     1008            42
    1200UTC 26.09.2023  156  18.6N  55.5W     1007            42
    0000UTC 27.09.2023  168  18.4N  58.2W     1005            37

The 12Z UKMET dropped this from becoming a TC. UK goes through 168.

[WxWatcher007]

40 minutes ago, Normandy said:

Not sure what you are seeing.  We have a major hurricane threat for the islands In next 8 days with an additional system behind it in the GFS.  There are no signs of the MDR shutting down until early to mid October.  People have gotta let the El Niño go lol it has lost.  Clearly something else is going on that is allowing the basin to produce in an epic fashion despite this El Niño.

I disagree in part. Nino definitely lost during the last four weeks, but the MDR is more hostile than it was even a week ago, particularly with SAL. Not enough to keep that wave from developing, but it may stunt its development for a bit. I do think we’re transitioning to the western Caribbean and SE coast as we approach October but that’s not saying much because that’s climo. Will waves keep rolling off, yeah, but development is probably going to be more delayed or halted altogether, especially if shear picks up in the eastern Caribbean. 

[Normandy]

My point is this.  My man said on 9/19 that the MDR is relaxing and implying that the MDR is shutting down.  Models all show a very active MDR the next 8-10 days.  This same line if thinking was used to assume the last four weeks would not happen when all seasonal models said it would.  If modeling is showing an active MDR why imply El Niño is going to hamper it when there has been zero evidence of traditional El Niño impacts to hurricane development this year?
 

 You are right climo does begin to shut down the MDR but that goes without saying.  it’ll be interesting the studies done on this season

[Ed, snow and hurricane fan]

40 minutes ago, WxWatcher007 said:

I disagree in part. Nino definitely lost during the last four weeks, but the MDR is more hostile than it was even a week ago, particularly with SAL. Not enough to keep that wave from developing, but it may stunt its development for a bit. I do think we’re transitioning to the western Caribbean and SE coast as we approach October but that’s not saying much because that’s climo. Will waves keep rolling off, yeah, but development is probably going to be more delayed or halted altogether, especially if shear picks up in the eastern Caribbean. 

I'm not sure the usual 'second season' in the Caribbean in October happens this year.

[NorthHillsWx]

54 minutes ago, Normandy said:

My point is this.  My man said on 9/19 that the MDR is relaxing and implying that the MDR is shutting down.  Models all show a very active MDR the next 8-10 days.  This same line if thinking was used to assume the last four weeks would not happen when all seasonal models said it would.  If modeling is showing an active MDR why imply El Niño is going to hamper it when there has been zero evidence of traditional El Niño impacts to hurricane development this year?
 

 You are right climo does begin to shut down the MDR but that goes without saying.  it’ll be interesting the studies done on this season

I said in 8-10 days it will begin to become more hostile. It still looks that way but in 6-8 days now. That doesn’t apply to the current wave which may develop before modeled shear increases, which looks substantial in MDR