2023 Atlantic Hurricane season

[Windspeed]

96L was another swing and a miss for mid range modeling. Too much shear 

I'm wondering if that's going to be a theme of the season. Yes, it's just the beginning of August, but there are bad placements of southern heat ridges and TUTTs to contend with that may very well not go away due to ENSO and strong upper evacuation out of the EPAC, regardless of the +AMO. Beating a dead horse here, but perhaps it bears repeating.

That August window of activity I was counting on looks to be getting smaller and smaller. Of course, even if a window of favorable upper pattern evolves over the MDR within the next few weeks as hinted by modeling, we've still got that pesky dry air and subsidence to deal with, which isn't abnormal in early-to-mid August.

[NorthHillsWx]

15 hours ago, Windspeed said:

 

I'm wondering if that's going to be a theme of the season. Yes, it's just the beginning of August, but there are bad placements of southern heat ridges and TUTTs to contend with that may very well not go away due to ENSO and strong upper evacuation out of the EPAC, regardless of the +AMO. Beating a dead horse here, but perhaps it bears repeating.

That August window of activity I was counting on looks to be getting smaller and smaller. Of course, even if a window of favorable upper pattern evolves over the MDR within the next few weeks as hinted by modeling, we've still got that pesky dry air and subsidence to deal with, which isn't abnormal in early-to-mid August.

 

Not to beat the dead horse, again, but something is really going to have to flip in mid august for CSU (and others’) predictions to come to pass. With a strengthening El Niño causing persistent shear issues in Caribbean and MDR I am struggling to see where tropical development will be favored outside of sub tropical spin ups and the possibility of a wave slipping through into the gulf. Seems it’s either going to be home grown systems or really slow especially in the H and MH department. Nothing seems to be breaking in the current pattern as we are now into august 

[GaWx]

 Despite the chance it had to be higher at the end due to 96L and 97L, July ends up with one storm (H Don, which way overperformed vs most expectations), which is near average and about double the average for an already moderate El Niño per OISST. Don along with 95L, 96L, and 97L means July was not at all inactive and was more active than a lot of Julys and even more-so considering it being a moderate El Niño.

[GaWx]

1 hour ago, NorthHillsWx said:

Not to beat the dead horse, again, but something is really going to have to flip in mid august for CSU (and others’) predictions to come to pass. With a strengthening El Niño causing persistent shear issues in Caribbean and MDR I am struggling to see where tropical development will be favored outside of sub tropical spin ups and the possibility of a wave slipping through into the gulf. Seems it’s either going to be home grown systems or really slow especially in the H and MH department. Nothing seems to be breaking in the current pattern as we are now into august 

 I agree that despite already being up to 5 NS and 1 H, these very active seasonal predictions will be tough to be reached. Regardless, this is a copy of a post from a non-met at another BB that I feel is relevant regarding July:

"I think it's important to look at why things didn't develop. 95L and 96L mostly suffered from dry air (typical for July), easterly shear for 95L (El Nino shear is supposed to be westerly), and an upper low for 96L (not exactly characteristic of an El Nino either). 

None of these seem to be under the influence of an El Nino, and reflect more of a July climo than anything else. I'm not sure if an average El Nino season even has that many invests with real potential in July, to begin with.

95L also almost developed in the Western Caribbean, and probably would have done so if it didn't run into Central America. That would have been almost unheard of in a typical El Nino year with shear raging across the Caribbean."

[tiger_deF]

While these waves aren't forecasted to develop until potentially much later, they sure look impressive.

[GaWx]

 This new run CANSIPS shear anomaly map, which is similar to the prior three runs, doesn't look the least bit like El Niño in that it has the opposite of the typical W shear anomalies in the Caribbean/MDR. From the perspective of a near coastal resident who sincerely doesn't want a lot of activity to worry about, this is downright concerning when also considering the very warm MDR and hopefully won't verify:

[Ed, snow and hurricane fan]

The trough along the East Coast looks to move W towards the central Great Lakes/Ohio Valley toward mid-month.  I suspect the Atlantic remains unfavorable with subsidence and dry air, but it would seem unlikely nothing at all (perhaps a non-tropical system becoming tropical) develops in the second half of August.  The Euro weeklies change a bit from run to run, but generally hint at activity near ECUSA latter half of August.

 

Hint of something not tropical on op GFS, an area of moisture with a very weak upper level disturbance near 40N/60W day 8 drifts SW toward the Bahamas around day 12, and from there, it looks like a standard tropical wave.  Moves across Florida, starts to organize in the Gulf, runs out of time.  Not to rely on a single op run, (hi, @ldub23) much of the run beyond the 10 day resolution truncation., but close in developments, maybe around the Bahamas, with higher heights to the E.  (That would bring back fond memories of 1976 and Hurricane Belle)

[NorthHillsWx]

3 hours ago, GaWx said:

 I agree that despite already being up to 5 NS and 1 H, these very active seasonal predictions will be tough to be reached. Regardless, this is a copy of a post from a non-met at another BB that I feel is relevant regarding July:

"I think it's important to look at why things didn't develop. 95L and 96L mostly suffered from dry air (typical for July), easterly shear for 95L (El Nino shear is supposed to be westerly), and an upper low for 96L (not exactly characteristic of an El Nino either). 

None of these seem to be under the influence of an El Nino, and reflect more of a July climo than anything else. I'm not sure if an average El Nino season even has that many invests with real potential in July, to begin with.

95L also almost developed in the Western Caribbean, and probably would have done so if it didn't run into Central America. That would have been almost unheard of in a typical El Nino year with shear raging across the Caribbean."

This is very accurate as to why those disturbances failed to develop, but I guess the spirit of my post was, with El Niño forecast to strengthen through the season, these forecasts relied on a front-loaded season to verify (unlike recent La Niña years). I guess it has already been somewhat front-loaded but it is very likely westerly shear will begin to increase at some point and if we’re still middling around with waves failing to get going or tracking weak mid latitude systems, it seems very unlikely to approach the extremely active forecasts that were adjusted upward after the season began. In other words, the window was expected to be now and if we punt too far, the door May slam shut on the hurricane season earlier than normal. So either we enter a hyperactive period before that happens or the predictions will be quite far from verifying especially on the hurricane, MH front.

As always, thanks for the excellent discussion @GaWx

[ldub23]

The  Ukmet forcast issued today. Since there are  no modeled hurricanes up to aug  17 i suppose sept  is  going to be one  hellova month. TWC 10/5 CSU 9/4 UKMET9/6

215 ace? I think 65 will be closer to reality.

JB is  continuing to backtrack while others go wild  with super active  forecasts.

 

Issued 01 August 2023

All values given below represent observed activity for the 6-month period from February to July 2023 plus the 6-month GloSea6 forecast activity from August 2023 to January 2024. Note, the official tropical storm season, which usually includes most activity, is from June-November.

The most likely number of named tropical storms (winds of at least 39 mph) predicted to occur in the North Atlantic is 19, with a 70% chance that the number will be in the range 14 to 24. The 1991-2020 long-term average is 14.

The most likely number of hurricanes (winds of at least 74 mph) predicted to occur in the North Atlantic is 9, with a 70% chance that the number will be in the range 6 to 12. The 1991-2020 long-term average is 7.

The most likely number of major hurricanes (winds of at least 111 mph) predicted to occur in the North Atlantic is 6, with a 70% chance that the number will be in the range 3 to 9. The 1991-2020 long-term average is 3. 

An ACE index of 215 is predicted as the most likely value, with a 70% chance that the index will be in the range 120 to 310. The 1991-2020 average is 123.

[Floydbuster]

The GEFS ensembles continue to show a Florida/Gulf hurricane mid-late August.

[GaWx]

43 minutes ago, Floydbuster said:

The GEFS ensembles continue to show a Florida/Gulf hurricane mid-late August.

The 12Z GEPS/CMC and 0Z EPS also show hints of increased activity for midmonth around the Bahamas to Gulf vicinity. This all appears to be from an AEW coming off within a few days. It really doesn't look quiet on the models in general from my perspective though model activity and actual TCs are not the same thing of course.

[Ed, snow and hurricane fan]

37 minutes ago, GaWx said:

The 12Z GEPS/CMC and 0Z EPS also show hints of increased activity for midmonth around the Bahamas to Gulf vicinity. This all appears to be from an AEW coming off within a few days. It really doesn't look quiet on the models in general from my perspective though model activity and actual TCs are not the same thing of course.

FWIW, Canadian ensembles also have a strong signal for a Central American Gyre that produces storms in both basins.  I don't usually look at the GEPS.  I don't know if GEM (and its ensembles) have improved in the last few years,  about 10 years ago it was like using the NAM in the tropics.

[GaWx]

21 minutes ago, Ed, snow and hurricane fan said:

FWIW, Canadian ensembles also have a strong signal for a Central American Gyre that produces storms in both basins.  I don't usually look at the GEPS.  I don't know if GEM (and its ensembles) have improved in the last few years,  about 10 years ago it was like using the NAM in the tropics.

GEM has changed over the last year or two from the Crazy Uncle (as named by JB many years ago), when it developed way too many, to almost the opposite with it developing way fewer and maybe too few. I don't know for sure whether that's better or worse but  I like the change.

[LongBeachSurfFreak]

18 hours ago, Ed, snow and hurricane fan said:

The trough along the East Coast looks to move W towards the central Great Lakes/Ohio Valley toward mid-month.  I suspect the Atlantic remains unfavorable with subsidence and dry air, but it would seem unlikely nothing at all (perhaps a non-tropical system becoming tropical) develops in the second half of August.  The Euro weeklies change a bit from run to run, but generally hint at activity near ECUSA latter half of August.

 

Hint of something not tropical on op GFS, an area of moisture with a very weak upper level disturbance near 40N/60W day 8 drifts SW toward the Bahamas around day 12, and from there, it looks like a standard tropical wave.  Moves across Florida, starts to organize in the Gulf, runs out of time.  Not to rely on a single op run, (hi, @ldub23) much of the run beyond the 10 day resolution truncation., but close in developments, maybe around the Bahamas, with higher heights to the E.  (That would bring back fond memories of 1976 and Hurricane Belle)

Belle likely would have been a hurricane at landfall on Long Island based on current water temps, keeping all other factors the same. We are loosing our hurricane buffer more and more. This will soon be prime hurricane coastline.

[TheDreamTraveler]

3 hours ago, LongBeachSurfFreak said:

Belle likely would have been a hurricane at landfall on Long Island based on current water temps, keeping all other factors the same. We are loosing our hurricane buffer more and more. This will soon be prime hurricane coastline.

That's something I forgot to even take into account. Those waters on the coast have saved NYC and New England from many a powerful hurricane. The only hurricanes that were able to cause massive damage were the ones that were barreling north so impossibly fast that the lag period of the storm weakening from being over the cooler waters would occur too late due to forward speed. And now we're getting to a point where you won't even need them to be barreling at high speeds for them to retain a lot of their overall strength

[olafminesaw]

10 minutes ago, TheDreamTraveler said:

That's something I forgot to even take into account. Those waters on the coast have saved NYC and New England from many a powerful hurricane. The only hurricanes that were able to cause massive damage were the ones that were barreling north so impossibly fast that the lag period of the storm weakening from being over the cooler waters would occur too late due to forward speed. And now we're getting to a point where you won't even need them to be barreling at high speeds for them to retain a lot of their overall strength

True, although water temps still certainly a limiting factor, even with such crazy anomalies. 

[tiger_deF]

The TW that just exited Africa is looking interesting.

[bigtenfan]

The 16 day GFS show a parade of waves leaving Africa but none of them make it past the middle of the MDR.

[Ed, snow and hurricane fan]

27 minutes ago, bigtenfan said:

The 16 day GFS show a parade of waves leaving Africa but none of them make it past the middle of the MDR.

The op shows a lot of dry mid-level (700-300 mb) air, which is what seems to stop each wave.  Not sure why the Atlantic is so dry, although downward motion is over the basin more often than upward motion, and sinking air will compress and heat up and have lower RH.  The general downward motion may be El Nino related.  One of the mets could confirm/elaborate

[NorthHillsWx]

4 hours ago, tiger_deF said:

The TW that just exited Africa is looking interesting.

This wave is getting some ensemble support this evening. Wouldn’t shock me to see something out of this

[tiger_deF]

18z GFS develops the pictured wave into a tropical storm, which crosses the Atlantic and degenerates into an open wave in 3-4 days after formation. Shear values are quite low in the area, and vorticity has been increasing on all levels over the past several hours. 

[Ed, snow and hurricane fan]

4 minutes ago, tiger_deF said:

18z GFS develops the pictured wave into a tropical storm, which crosses the Atlantic and degenerates into an open wave in 3-4 days after formation. Shear values are quite low in the area, and vorticity has been increasing on all levels over the past several hours. 

The op Euro tries to develop something from the 3 clusters of storms offshore and nearshore Africa.  Middle level RH just N of the system is dry, but I think the issue is shear.  The disturbance is just S of an anticyclone which has low shear under the anticyclone but higher shear (rising in a short distance to over 20 knots) from the E just S of the anticyclone, over where best mid level RH is.  18Z GFS version is the wave moves out of the good moisture and dies in the desert.  The three blobs thing also may mean the system is strung out (TPW product suggests it as well), which seemed to be part of the issue with 95L and 06L.  But with some ensembles and the op Canadian develop something, it may provide something to talk about the next two weeks.  Especially with Euro ensembles showing a couple of mid Atlantic landfalling cyclones in 2 weeks

[tiger_deF]

If limited model support continues, I imagine this disturbance may become a lemon in the near future.

[WxWatcher007]

 

[Ed, snow and hurricane fan]

I don' really see CSU coming close to verifying.  Op GFS still going 16 days w/o a named storm, ensembles are kind of 'meh', and there seems to be a lot of dry air Central/Eastern MDR.  Where the upper convergence/subsidence is.  What activity the GEFS do see seems to form past 50W.  Yesterday's Euro weeklies still seem to like late August for W based systems that could be close enough to ECUSA to be interesting.

[Chinook]

16 minutes ago, Ed, snow and hurricane fan said:

I don' really see CSU coming close to verifying.  Op GFS still going 16 days w/o a named storm, ensembles are kind of 'meh', and there seems to be a lot of dry air Central/Eastern MDR.  Where the upper convergence/subsidence is.  What activity the GEFS do see seems to form past 50W.  Yesterday's Euro weeklies still seem to like late August for W based systems that could be close enough to ECUSA to be interesting.

The 00z, 06z and 12z GFS all have storms being the Gulf of Mexico, but it's a long way out. This is, of course, the time when you'd like to see the models have a couple of developing systems in the central Atlantic if you were expecting kind of a normal start to the season.

[lee59]

On 8/2/2023 at 8:37 AM, LongBeachSurfFreak said:

Belle likely would have been a hurricane at landfall on Long Island based on current water temps, keeping all other factors the same. We are loosing our hurricane buffer more and more. This will soon be prime hurricane coastline.

Long Island is so over due for a direct hit, almost 40 years since the last hurricane hit the Island directly.

[tiger_deF]

Models:

The Eastern Atlantic:

[Ed, snow and hurricane fan]

CIMSS MIMIC TPW product already shows lower PW air being drawn into the disturbance SW of the CVs.  I don't think the GFS is far from wrong showing that wave disappearing in the dry air.  It wouldn't be the first good looking wave that quickly disappears this year.

 

I think there is a much higher chance of something subtropical, not yet well modeled, forming off the East Coast, than anything MDR, for at least a week.

[Ed, snow and hurricane fan]

46 minutes ago, ldub23 said:

I  have  no idea why CSU didnt  lower  numbers. Its  possible a  very weak frontal low could  be called a tropical storm but  AUG is  looking at  0/0

 

The Euro and GFS ensembles may be be starting to pick up on the activity the Euro weeklies are predicting after mid-month.  It has a fishy look, but get the storms first, then worry about the steering.  Another 0/0 August probably doesn't happen.