2019 Indicators: SST'S / Sal / MSLP / Steering / Shear / Instability (See updated graphics at first post)

[Kingarabian]

No guarantee -NAO will continue beyond mid-Aug. Euro weeklies and CFS both suggest neutral to positive NAO returns second half of Aug.

:uarrow: With this kind of pattern everything should track safely offshore the east coast either between the east coast and Bermuda or east of that.

May have to watch to see how things play out come late-September into October for Western Caribbean development that could potentially threaten the U.S. thanks to the -NAO.

Also, no guarantee that a tropical system will safely move offshore while moving along the East Coast. A deep enough trough oriented "the right way" could easily pull a system northward into the Northeast US or Atlantic Canada even with a -NAO.

Yup.

[NDG]

No guarantee -NAO will continue beyond mid-Aug. Euro weeklies and CFS both suggest neutral to positive NAO returns second half of Aug.

Also, no guarantee that a tropical system will safely move offshore while moving along the East Coast. A deep enough trough oriented "the right way" could easily pull a system northward into the Northeast US or Atlantic Canada even with a -NAO.

Like what we saw with Sandy (2012)

Ridging over SE Canada & maritimes is what really caused
Sandy to take a left hook. Had it been a true -NAO pattern for being in late October it would had gone out to sea.

[USTropics]

Also, no guarantee that a tropical system will safely move offshore while moving along the East Coast. A deep enough trough oriented "the right way" could easily pull a system northward into the Northeast US or Atlantic Canada even with a -NAO.

Like what we saw with Sandy (2012)

Ridging over SE Canada & maritimes is what really caused
Sandy to take a left hook. Had it been a true -NAO pattern for being in late October it would had gone out to sea.

A Greenland blocking pattern (also saw one in 2018 in addition to Sandy) has a significant effect on hurricane tracks, even when a -NAO is present. The GBI (Greenland Blocking Index - uses spatially-averaged 500 hPa geopotential heights over Greenland) during Sandy (late Oct) was more inline with a GBI for June.

[crownweather]

No guarantee -NAO will continue beyond mid-Aug. Euro weeklies and CFS both suggest neutral to positive NAO returns second half of Aug.

Also, no guarantee that a tropical system will safely move offshore while moving along the East Coast. A deep enough trough oriented "the right way" could easily pull a system northward into the Northeast US or Atlantic Canada even with a -NAO.

Like what we saw with Sandy (2012)

No, more like hurricanes of the past such as Bob (1991), Gloria (1985), Carol (1954), 1938 hurricane and also likely hurricanes such as 1635 and 1815. All hurricanes in the NE US had 1 synoptic feature in common. A upper level trough of low pressure over the Ohio Valley. What is important is the tilt of that trough. If it's a positive trough, where the trough is angled from NE to SW, then hurricanes coming up the coast would be steered out and away. On the other end of the spectrum, if it's a negative tilted trough, one that is tilted from NW to SE, the upper level flow is such that a tropical system is sucked northward right up the East Coast into New York and New England.

So, even if you have eastern troughiness during a -NAO, that trough can back off a little and shift into the Ohio Valley allowing for that corridor where storms can move northward through.

[NDG]

And just like that the shear over the Caribbean is abating little by little. GOM is not so good any more.

[Hurricane Andrew]

Also, no guarantee that a tropical system will safely move offshore while moving along the East Coast. A deep enough trough oriented "the right way" could easily pull a system northward into the Northeast US or Atlantic Canada even with a -NAO.

Like what we saw with Sandy (2012)

No, more like hurricanes of the past such as Bob (1991), Gloria (1985), Carol (1954), 1938 hurricane and also likely hurricanes such as 1635 and 1815. All hurricanes in the NE US had 1 synoptic feature in common. A upper level trough of low pressure over the Ohio Valley. What is important is the tilt of that trough. If it's a positive trough, where the trough is angled from NE to SW, then hurricanes coming up the coast would be steered out and away. On the other end of the spectrum, if it's a negative tilted trough, one that is tilted from NW to SE, the upper level flow is such that a tropical system is sucked northward right up the East Coast into New York and New England.

So, even if you have eastern troughiness during a -NAO, that trough can back off a little and shift into the Ohio Valley allowing for that corridor where storms can move northward through.

Makes sense...all you need is a window, even in an "unfavorable" pattern. We've seen it time and time again with tropical cyclones, and with winter storms.

[TheStormExpert]

Something tells me that September could be quite favorable on its own without the help from the MJO like last season.

 https://twitter.com/dcareawx/status/1156401897256968192

[SFLcane]

There is another potent wave right behind future 96L rolling of the african coast.

[SoupBone]

Something tells me that September could be quite favorable on its own without the help from the MJO like last season.

https://twitter.com/dcareawx/status/1156401897256968192

Something I've watched as well. SAL doesn't seem to be far enough South to impact these systems as much as previous years.

[Monsoonjr99]

Things just keep seeming evermore favorable as of late...

Not to doomcast, but I have an uneasy feeling about this season. Another very active and destructive season like 2017 cannot yet be ruled out. It's pretty much down to steering at this point.

I'm still holding to my 16-9-4 prediction from pre-season (which I regarded as bullish at the time) as nothing has convinced me to lower it. Cooling ENSO (especially to the east), strong WAM, warm MDR (tho EOF 2 +AMO), lower shear, and weaker SAL are all signs.

[USTropics]

After quite a dip, ensemble forecast is for the NAO to go positive second 1/2 of August:

[Shell Mound]

Despite the record-long stretch of -NAO, the MDR is not substantially warmer now than it was prior to the onset of the -NAO. This is a certainly not a good sign for an active season—given that the MDR is still near average, with EOF 2 +AMO (warm subtropics) remaining largely unchanged. Additionally, weak El Niño conditions have persisted longer than I expected and now seem unlikely to change substantially through most of ASO. This means that both sinking air and strong shear (TUTTs) are likely to persist through the peak of the season, limiting chances for both homegrown (mainly Caribbean) and African development. So far, the trends are good news for the Caribbean and the mainland U.S., since most major landfalls tend to originate in either the MDR or the Caribbean, not the subtropics (including the Gulf).

[NotSparta]

Despite the record-long stretch of -NAO, the MDR is not substantially warmer now than it was prior to the onset of the -NAO. This is a certainly not a good sign for an active season—given that the MDR is still near average, with EOF 2 +AMO (warm subtropics) remaining largely unchanged. Additionally, weak El Niño conditions have persisted longer than I expected and now seem unlikely to change substantially through most of ASO. This means that both sinking air and strong shear (TUTTs) are likely to persist through the peak of the season, limiting chances for both homegrown (mainly Caribbean) and African development. So far, the trends are good news for the Caribbean and the mainland U.S., since most major landfalls tend to originate in either the MDR or the Caribbean, not the subtropics (including the Gulf).

Not so sure about that last sentence

Also, the TUTTs now being linked to El Niño sounds dubious, given how high shear (compared to average) has been rather absent during July. But, it does correlate well w/ the arrival of a strong suppressive CCKW

[TheStormExpert]

Despite the record-long stretch of -NAO, the MDR is not substantially warmer now than it was prior to the onset of the -NAO. This is a certainly not a good sign for an active season—given that the MDR is still near average, with EOF 2 +AMO (warm subtropics) remaining largely unchanged. Additionally, weak El Niño conditions have persisted longer than I expected and now seem unlikely to change substantially through most of ASO. This means that both sinking air and strong shear (TUTTs) are likely to persist through the peak of the season, limiting chances for both homegrown (mainly Caribbean) and African development. So far, the trends are good news for the Caribbean and the mainland U.S., since most major landfalls tend to originate in either the MDR or the Caribbean, not the subtropics (including the Gulf).

That last sentence is not true. All Cat.5 U.S. hurricane landfalls have originated from in-close development. And yes there has been a handful of majors hit the U.S. from Subtropical origin.

[CyclonicFury]

I think it's very premature to talk about "season cancel" after the models dropped 96L. Remember 99L in 2017? That invest struggled in the MDR and eventually developed into Gert when it reached the subtropics. Models initially were strongly in agreement it would develop over the MDR, but eventually they all dropped it at once, similar to what we are seeing here. Not saying this season will be like 2017, but the MDR doesn't usually get that favorable for TCs until very late August.

Let's see what happens with 96L first. There have been numerous occasions in the past where models dropped a system only to pick it back up.

As I said above, I don't think this is related to El Niño, it's just the tropical Atlantic *may not* be not ready yet.

[TheStormExpert]

Ben Noll with an August shutdown tweet.

 https://twitter.com/bennollweather/status/1156932595734609920

[TheStormExpert]

I think it's very premature to talk about "season cancel" after the models dropped 96L. Remember 99L in 2017? That invest struggled in the MDR and eventually developed into Gert when it reached the subtropics. Models initially were strongly in agreement it would develop over the MDR, but eventually they all dropped it at once, similar to what we are seeing here. Not saying this season will be like 2017, but the MDR doesn't usually get that favorable for TCs until very late August.

Let's see what happens with 96L first. There have been numerous occasions in the past where models dropped a system only to pick it back up.

As I said above, I don't think this is related to El Niño, it's just the tropical Atlantic *may not* be not ready yet.

Yeah but the TUTT is located in the Subtropical Atlantic. It’s not so much the Tropical Atlantic.

[tolakram]

It's season cancel season.

[NotSparta]

Ben Noll with an August shutdown tweet.

https://twitter.com/bennollweather/status/1156932595734609920

Guess he didn't learn anything from all those tweets to him the other day

[SoupBone]

It's season cancel season.

Like groundhog day...