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Tropical Season 2017

40/70 Benchmark

By 40/70 Benchmark,
in New England

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Typhoon Tip

Typhoon Tip

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Well .. NHC has gone and downgraded their risk assessment on 99L ... stands to reason based on seasonal trend like I was cautioning it may. At least, the seasonal trend appears to have struck again - SAL.

After having analyzed the other three typical suspects,  Shear, SST/heat content, and upper level divergence, there does not appear to be any other mitigation to development of this robust circulation. The fact that it is devoid of convection is telling...and what convection there is is pock-marked CB's that are behaving like air-mass pulse variety thunderstorms like you get over land.  The convection is failing to self sustain and presently ...the SAL product does indicate a region of contaminated air is located immediately astride the TW region on the N side of its perceived circulation.  And that's the ball-game... 

They are probably right to upgrade 90L as it is leaving an area of shear behind and is moving up under a region of lowering shear and also divergent motion in the vectors in the upper altitudes... And of course, over some of the hottest oceanic waters on the planet: the western Caribbean August jacuzzi. SAL doesn't appear to be a factor as is usually the case by the time these features succeed between 60 and 70 W.

As for 99L...all is not lost... I think given to it's huger than normal circulation medium ...that arithmetically means it's got a lot of mass thus momentum and it could outlast the toxifying affects of the SAL plume ...if that's really the cause for it's belated classification.  I think it is though based on most obvious available/observable evidence.  Models have eased off the throttle in the last couple of cycles.

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40/70 Benchmark

40/70 Benchmark

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20 minutes ago, Typhoon Tip said:

Well .. NHC has gone and downgraded their risk assessment on 99L ... stands to reason based on seasonal trend like I was cautioning it may. At least, the seasonal trend appears to have struck again - SAL.

After having analyzed the other three typical suspects,  Shear, SST/heat content, and upper level divergence, there does not appear to be any other mitigation to development of this robust circulation. The fact that it is devoid of convection is telling...and what convection there is is pock-marked CB's that are behaving like air-mass pulse variety thunderstorms like you get over land.  The convection is failing to self sustain and presently ...the SAL product does indicate a region of contaminated air is located immediately astride the TW region on the N side of its perceived circulation.  And that's the ball-game... 

They are probably right to upgrade 90L as it is leaving an area of shear behind and is moving up under a region of lowering shear and also divergent motion in the vectors in the upper altitudes... And of course, over some of the hottest oceanic waters on the planet: the western Caribbean August jacuzzi. SAL doesn't appear to be a factor as is usually the case by the time these features succeed between 60 and 70 W.

As for 99L...all is not lost... I think given to it's huger than normal circulation medium ...that arithmetically means it's got a lot of mass thus momentum and it could outlast the toxifying affects of the SAL plume ...if that's really the cause for it's belated classification.  I think it is though based on most obvious available/observable evidence.  Models have eased off the throttle in the last couple of cycles.

I was just noting that.

Hopefully it survives because personally, I'd rather it develop further west.

The one in the caribbean looks lame because its going to interact with the Yucatan and/or C. America, so of course that is the one that avails itself of a more favorable environment. 

The atmosphere just continues to manufacture ennui.

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Typhoon Tip

Typhoon Tip

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Well ... not for not... for those that are wantonly and irresponsibly hoping for some sort of a horrifying redux of ...just about any example of lore ..., that particular clustering of forecast' tracks above is through the proverbial key-hole that tends to precede run ups along the eastern seaboard.  Let us set the table for a moment and pretend 99L survives the SAL toxicity ... and wends its way up through that 60 nautical mile, NE of Puerto Rico climate favored trajectory as a belated developer. Such visions of a Bahama-Bomb requires pure speculation (of course..), but... Bob and many others have shown that you can detonate bombs in pretty short space and time.

One aspect in the total envelope of considerations therein, however ...is that WAR is unilaterally modeled to flex stronger during that same modeled time frame of that track sequencing? If so...that would stop any smooth parabolic turn up the coast. The west-Atlantic ridging would tend to block that from happening.  It almost seems that under such a regime, any would-be TC might end up stranded somewhere around the Bahamas ... perhaps pinned down under the WAR's blocking influence.

Lot of possibilities there... The WAR could weaken (say) and allow a window for it to "cut through" ...to which indeed...areas from the upper MA, to NE and over to NS might be interested; because one thing that is consistently modeled and has a long hardened trend of success is that trough over SE Canada and the weakness that subtends beneath it toward the OV would be lurking as a potential capturing influence should its circulation particulars modulate the right way - any such latter predictive facets are presently oblivious to all methods, both machine and man.  We are just creatively assessing things here... WAR could also just materialize with a weakness in place, too.   Or not all..  

Some of the earlier runs (like 5 days ago or something...) did offer solutions similar to those just described ...bringing an important system within a egads distance.  Personally, the cyclonic appeal on satellite seems to be weakening as 99L's convection continues to be impeded.  Without the sustaining convection, ...inflow into that region doesn't take place (conservation of mass), and the region just absorbs into the Maritime-monsoonal trough of the ITCZ.  

I wonder if the models et al even have physics in them for SAL factorization. It seems if there is something there that is in the initialization grid at all...if other parameters are in line the models will go ahead and spin it up and send down stream... The CMC being most guilty of that... pure speculation.  

 

 

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Typhoon Tip

Typhoon Tip

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"it should re-curve" is the course of least regret ... 

There's nothing particularly endemic about the circulation medium, nor the models, ...that signals that has to happen, above and beyond the usual statistical noise of the Basin out there though.  

It's a number game at this sort of time lead.   The fact of that matter is ...getting a TC to churn and burn it's way successfully through all the enumerable critical key-holes it has to succeed in doing is almost akin to winning a lottery.  The high N of it has to continually direct it to about 60 naut miles ENE of PR ...toward a weakness of sufficient structure to impart a nice parabolic turn NW turn through the outer Bahamas *without shearing it ... and dry air can't be lurking over the SE U.S. to get sucked into the circulation and weaken it ...and the timing of the capturing influence of the westerlies and it's geometry have very narrow band-widths for error as far as what happens should all that succeed prior to the turn to N ...on and on and on and on. 

There's a ton of moving parts and the fact of the matter is, with any envelope of plausible destinies being a 100 ... any one of them means you have a 1% chance of that one sought after result actually occurring.

So yeah... there's a 99% chance that something else will take place. 

But, strikes up this way do take place ...if however rarely so.  Personally, I don't think the plague of eastern weakness in the heights if out outright trough that's dominated the summer is a terrible circumstance for enthusiasts - at least as an initial table setting..  That's the thing, I'm not saying the situation with the Atlantic is always a 100::1 game of odds.  Every year and circumstance changes the landscape of probabilities a little, depending upon what is actually taking place... This time..I think we can eliminate early re-curves due to preponderant WAR ..  

Currently 99L is passing right headlong through shear...  However, and this may be what the more robust models are responding too... there is a relaxation in that shear ~ to 55 W... and from there up through the outer Bahamas, that particular mitigating factor is less than inhibitory. 99L should begin moving up under the eastern edge of improving shear in about 24 hours.  

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wxeyeNH

wxeyeNH

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The big hurricanes for New England are the ones that have a strong trough west of us to quickly yank them up before they lose intensity.  Like 1938.   My mind is fried right now.  Are there any good examples where an early season cane has moved WNW through a weakness in the Bahama area and slowly rounded a Bermuda high without a strong trough to our west?  Once they get to about the latitude of the Carolina's  they  weaken considerably if there not chugging NE bound.  Of course you have to the destructive winds are  in the east quads. A benchmark track is not going to bring hurricane conditions to areas much further NW than the Cape and thus its a noreaster type storm with lots of rain and gusty northeast winds....

Boy, statically the US is now due for a major...  I believe its been 11 years now which is the longest recorded time.  Am I right?

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Hoth

Hoth

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17 minutes ago, wxeyeNH said:

The big hurricanes for New England are the ones that have a strong trough west of us to quickly yank them up before they lose intensity.  Like 1938.   My mind is fried right now.  Are there any good examples where an early season cane has moved WNW through a weakness in the Bahama area and slowly rounded a Bermuda high without a strong trough to our west?  Once they get to about the latitude of the Carolina's  they  weaken considerably if there not chugging NE bound.  Of course you have to the destructive winds are  in the east quads. A benchmark track is not going to bring hurricane conditions to areas much further NW than the Cape and thus its a noreaster type storm with lots of rain and gusty northeast winds....

Boy, statically the US is now due for a major...  I believe its been 11 years now which is the longest recorded time.  Am I right?

You are correct, sir. Per the historical record, we are way overdue for a major. "We" meaning the U.S., not NE specifically, although it's been over 50 years since a major here too, so maybe we're due in the next decade or two?

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Typhoon Tip

Typhoon Tip

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33 minutes ago, wxeyeNH said:

The big hurricanes for New England are the ones that have a strong trough west of us to quickly yank them up before they lose intensity.  Like 1938.   My mind is fried right now.  Are there any good examples where an early season cane has moved WNW through a weakness in the Bahama area and slowly rounded a Bermuda high without a strong trough to our west?  Once they get to about the latitude of the Carolina's  they  weaken considerably if there not chugging NE bound.  Of course you have to the destructive winds are  in the east quads. A benchmark track is not going to bring hurricane conditions to areas much further NW than the Cape and thus its a noreaster type storm with lots of rain and gusty northeast winds....

Boy, statically the US is now due for a major...  I believe its been 11 years now which is the longest recorded time.  Am I right?

There are papers out there ... I know, I've seen them... I cannot recall if they were just NWS observations/write-ups, or if they were other research efforts... But, there are recognized circumstances in the atmosphere that seem to precede systems effecting the upper MA and New England regions. 

one is as you say, some sort of weakness in the geopotential medium ~ 80W.  I don't think it has to be much.  It's really more a factor of whether one is there or not, and ..relative to that the heights east over the west Atlantic mirror the other direction.   The difference between the two provides a baser conduit ...and the hurricanes will always travel along the path of least resistance - which is really just code for where ever the steering is directing them. 

the other is that there tends to be some sort of upper level jet max escaping ENE near Maine.  Not sure what the significance of that is (mechanically) to the rest of the field, though I hunch.  I did read in an NWS write-up once that there tends to be a 400 to 200 mb sigma level just acceleration in that vicinity during many events that were expressed N up along the EC.  It's probably just a function of the overall blocking regime is my hunch.  If a hurricane is forced to move N at our latitude, that means some form of blocking must be taking place E-N of our region, and usually where there is blocking ...the arc the demarcates it to the openness of the westerlies has a band of higher wind velocities. In that respect, the wind max is sort of indirectly signals the existence of some kind of resistance to move TC's to the E once they've turned N.

I'm sure all this stuff can be found with Google.  In any case, just about all hurricane that did a '38, or a Gloria ... Irene... Sandy...they had structures in variation of these above. 

The other thing ..I don't speak for anyone other than myself but I've never been a fan of the 'statistically due' argument.  The problem with that (obviously) is that averages don't say anything that describes 'when' things take place.  If we are supposed to get 70" of snow, that is based on 10" to 200" and every possible decimal total in between that's ever happened.  Same exact logic of uncertainty applies in the behavior of TC strikes.  We could get 10 in 30 years, then nothing for 70 and still average the same in 100 over all... There's no real "due date" in that...

 

  

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NJwx85

NJwx85

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I know that Sandy didn't affect New England in the same way that it did the NYC and upper Mid-Atlantic however as far as filling an anomaly for serious East coast tropical threats, I'm fairly certain we're good for awhile. We also had a direct impact from Irene in 2011.

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Ginx snewx

Ginx snewx

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15 minutes ago, WxWatcher007 said:

I won't get into the technicalities of the Sandy classification debate, but no doubt, it was a big time event for much of the NYC/upper MA region. Can't remember how well CT dealt with it, but Irene was a big deal along the CT coast, particularly in East Haven. That said, a major up the coast and over SNE would be a catastrophe IMO, not only because of the surge but the wind potential further inland if that storm is moving rapidly. There have been a number of events to weed out weak/dead trees, but a bona fide major hurricane would still do major damage IMO. 

Westerly RI

 

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