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Tropical Season 2017

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37 minutes ago, Typhoon Tip said:

That experimental tool, "Roundy Probabilities" ... it used to be mentioned in TPC discussions (and NCEP) from time to time to herald intra-montly periods of enhanced chances. I haven't seen it reference/ read in any discussion in recent years tho. I'm only mentioning this because I don't know what it's verification scoring/technique is, and why/if NCEP has stopped referencing it ..."maybe" that means it's not useful?  I'm not sure if they do use it... 

Lotsa 'who knows' in that paragraph. But, the product does still exist out there and is available to general web consumption. pr.jpg

Right now, it is flagging the Cape Verdi "rail-system" as mid-grade positive anomaly chances for development over the next three to five days, which is interestingly ..right when rather abruptly the operational versions of the main player global numerical model types have begun developing/tracking a system of interests.  

As usual, the CMC has a Category 6.4 Jesus H. Christer preparing to denude the Windward Islands off the face of the planet... While in a shocking move by the Euro, with its proclivity to ignore zygote tropical waves entirely ... it even "dents" the PP (a remarkable achievement for that particular guidance source).  Whether it does or does not lend support/confidence to any genesis actually occurring, the Euro "seems" like we could say, 'see, even the Euro thinks so!'   The last two runs of the GFS have it as well, the latter of which was quite robust/intense actually, with a long tracker CV hurricane implied.  

That all said, there a giant wave that has just scooted off western Africa/Sierra Leona ... Rumor has it, it's trapped the Ebola virus in its circulation envelope and is going to deliver that particular cargo along with storm's entertainment to the dystopian zealot base of internet social-media users ...all the way across the ocean. 

No ..of course not, heh.  But, that is a pig circulation!  Truly enormous.  One thing I have noticed about the tropics so far this season is that SAL (Saharan Air Layer seen below) has been preponderant, and most probably culprit in laying strong-ish tropical waves into the annuls of failed spin ups.  

We can't "blame climo" ...doesn't work that way.  What we can do is look at climo, and then if there are a dearths (or opposite) of activity ...go investigate why the dearth (or opposite) tend to take place. Now, I don't know if SAL is an endemic circumstance of pre-August Atlantic seasons more so than later in the seasons?  But, it has definitely been so far this year, intermingling with these circulation zygotes a lot this year.  It's a toxin, and therefore initially safe to assume as having limited development to date. As we can see in the below image... this particular tropical wave of interest is more free of that toxic air mass interaction.  tw.jpg

So .. fwiw, we have a few indicators that suggest we headed for some increasing activity/things to watch in the tropics.  August typically is a month that sees spikes inactivity as the curve of frequency is pretty positively sloped over the next several weeks.    

Do you think the SAL is pushing these waves farther south than usual? Seems like there's been more activity down around 10N than normal, but perhaps that is just my biased perception.

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2 hours ago, Hoth said:

Do you think the SAL is pushing these waves farther south than usual? Seems like there's been more activity down around 10N than normal, but perhaps that is just my biased perception.

Nah, ..it's not that type of forcing ..  SAL is about two things:  the thermodynamics of the sounding; aerosols of dust particles.  

Both have origin over the arid stretches of a the continent of Africa.  

The thermodynamic aspect is a thermally charged layer of atmosphere that extends/suspends many 10 of mbs vertically through the sounding as very hot air - most notably around 850, but it can reach altitudes to the 600 sigma level.  It is hot and very dry... Almost like an EML on roids ha

The dust aspect is quite literally Saharan dust kicked up from normal dust/sand storm activities over the vastness of the desert regions of N Africa.  It's endemically a part of that same air mass; chances are ... if you find a SAL layer of temperature, you've got a preponderance of dust in that same mass of atmosphere. 

It's thought to be bad for tropical cyclone formation because it's "too much of a good thing."   The way SAL is thought to toxify is that the rising air entrains and mixes with the dust, ...thus becoming 'over-seeded' with condensation nuclei (those microscopic grains of just about anything that is in the air that molecules of water cling to when they lose energy).  

Thus, cloud development takes place too efficiently at lower altitudes, releasing so much water so fast that there is nothing left to sustain deeper tropospheric most adiabatic instability - which is that process where condensation releases heat to the parcel which further destablizes it and keeps it rising... Once that moisture is used up (or reaches static equilibrium of potential loss to the parcel versus the parcels surrounding environment) ...game over. The cloud never reaches the anti-cyclone level of divergence in the higher levels and the "engine" of the cyclone is choked.  

SAL is about contamination, not blocking in the sense of ridges and troughs.  

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3 minutes ago, Typhoon Tip said:

Nah, ..it's not that type of forcing ..  SAL is about two things:  the thermodynamics of the sounding; aerosols of dust particles.  

Both have origin over the arid stretches of a the continent of Africa.  

The thermodynamic aspect is a thermally charged layer of atmosphere that extends/suspends many 10 of mbs vertically through the sounding as very hot air - most notably around 850, but it can reach altitudes to the 600 sigma level.  It is hot and very dry... Almost like an EML on roids ha

The dust aspect is quite literally Saharan dust kicked up from normal dust/sand storm activities over the vastness of the desert regions of N Africa.  It's endemically a part of that same air mass; chances are ... if you find a SAL layer of temperature, you've got a preponderance of dust in that same mass of atmosphere. 

It's thought to be bad for tropical cyclone formation because it's "too much of a good thing."   The way SAL is thought to toxify is that the rising air entrains and mixes with the dust, ...thus becoming 'over-seeded' with condensation nuclei (those microscopic grains of just about anything that is in the air that molecules of water cling to when they lose energy).  

Thus, cloud development takes place too efficiently at lower altitudes, releasing so much water so fast that there is nothing left to sustain deeper tropospheric most adiabatic instability - which is that process where condensation releases heat to the parcel which further destablizes it and keeps it rising... Once that moisture is used up (or reaches static equilibrium of potential loss to the parcel versus the parcels surrounding environment) ...game over. The cloud never reaches the anti-cyclone level of divergence in the higher levels and the "engine" of the cyclone is choked.  

SAL is about contamination, not blocking in the sense of ridges and troughs.  

That was a fascinating read. Thanks very much.

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18z GFS brings a monster hurricane to the northern Bahamas and tracks it into SC and NC and then as a weak hurricane or tropical storm with a 973mb pressure into SNE at around 274 hours, at least we are within 11 days

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This is the 18z GFS August 3rd 2017 run for Invest 99L at day 10 240 hours.  Winds are 113-knots and pressure is around 937mb, in another 34 hours it goes from the Bahamas to the SNE coastline

99L invest 937mb Franklin future.png

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This system is so far away that anything could happen.  As an astronomy buff too, I am already starting to look ahead to potential large scale synoptic systems that could muck up this August 21rst total eclipse fromt the Tennessee Valley ESE to South Carolina.  Pop up afternoon convection is one thing but a large tropical/synoptic system of some sort is another beast entirely.  A hurricane is a long shot but some type of decaying system has higher odds.  If this East Atlantic system would take the longer loop into the Gulf and then move NE in the flow the timing could screw up Aug 21rst for tens of millions.  Although I enjoy tracking and watching hurricanes a large event right around Aug 21rst would add insult to injury.  I am hoping for an out to sea solution!

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6 minutes ago, wxeyeNH said:

This system is so far away that anything could happen.  As an astronomy buff too, I am already starting to look ahead to potential large scale synoptic systems that could muck up this August 21rst total eclipse fromt the Tennessee Valley ESE to South Carolina.  Pop up afternoon convection is one thing but a large tropical/synoptic system of some sort is another beast entirely.  A hurricane is a long shot but some type of decaying system has higher odds.  If this East Atlantic system would take the longer loop into the Gulf and then move NE in the flow the timing could screw up Aug 21rst for tens of millions.  Although I enjoy tracking and watching hurricanes a large event right around Aug 21rst would add insult to injury.  I am hoping for an out to sea solution!

Ha...that's funny ..   Imagining all these people booking rooms and planning trips to someplace and that someplace dawns overcast and rainy.  Better yet, not forecast to be that way, too - 

If I were god I would make a thick tube of cloudiness that is exactly the same width as the Umbra ...and have that tube of clouds thin slightly over the Penumbra ... then, have it all look easily explainable as random chance with synoptic weather across the U.S... thus concealing my deviance.

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43 minutes ago, wxeyeNH said:

This system is so far away that anything could happen.  As an astronomy buff too, I am already starting to look ahead to potential large scale synoptic systems that could muck up this August 21rst total eclipse fromt the Tennessee Valley ESE to South Carolina.  Pop up afternoon convection is one thing but a large tropical/synoptic system of some sort is another beast entirely.  A hurricane is a long shot but some type of decaying system has higher odds.  If this East Atlantic system would take the longer loop into the Gulf and then move NE in the flow the timing could screw up Aug 21rst for tens of millions.  Although I enjoy tracking and watching hurricanes a large event right around Aug 21rst would add insult to injury.  I am hoping for an out to sea solution!

That scenario would be so unfortunate.  I'm glad I don't have to reserve a hotel, buy a plane ticket, and plan a vacation week out of it like many are doing just because something like this could happen. Everything is easier when you have a family member in the area.

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I would advise big caution with the GFS. The GFS has been generating just absurd amounts of PWATs that may be causing it to go James from latent heat due to convection. The NHC was actually against the GFS upgrade because of this from what I gather. It sounds like a really bad issue. 

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10 minutes ago, 40/70 Benchmark said:

Sometimes persistence wins.

Ha haa!  Good one, and echoes my sentiments exactly -  

...I'd actually push that sarcasm back through since 2015's juggernaut February snows for that matter..   Seems ever since that 'climate event' we've been in a dearth of climatic events, regardless of type. 

But back to point...  I'd also be a little concerned that the models have been, overall, a bit over-zealous with spin ups.  Not by a lot, but enough so that I wonder how much of the present modeled appeal is over-done.   

For one, as I elucidate above, the SAL contamination along that region of the Atlantic appears to be in play this year (so far) as a mitigating factor.  That doesn't mean it will continue to do so, but that has [apparently] interfered with some of the prior modeled antics. 

It actually surfaces a question for me regarding whether or not SAL-related dynamics are even factored into the models. It seems that TPC keeps putting "X" 's on their chart for early chances for development based almost purely upon the models. In fact (oddly enough...) it appears to be the CMC, whether by coincidence or not.   When that model closes off isobars and then tracks a hornet sting west, it's been automatic on TPC web-page.  

Anyway, they've had to wipe those off the chart when the model(s) summarily stop developing, and in each case I've noticed that clusters associated with the target disturbances/TW's were demolished by SAL entanglements.   There is still SAL preponderant out there ...just wonderin' if this goes like so many before. Just adding caution to Scott's thing -

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20 minutes ago, Typhoon Tip said:

Ha haa!  Good one, and echoes my sentiments exactly -  

...I'd actually push that sarcasm back through since 2015's juggernaut February snows for that matter..   Seems ever since that 'climate event' we've been in a dearth of climatic events, regardless of type. 

But back to point...  I'd also be a little concerned that the models have been, overall, a bit over-zealous with spin ups.  Not by a lot, but enough so that I wonder how much of the present modeled appeal is over-done.   

For one, as I elucidate above, the SAL contamination along that region of the Atlantic appears to be in play this year (so far) as a mitigating factor.  That doesn't mean it will continue to do so, but that has [apparently] interfered with some of the prior modeled antics. 

It actually surfaces a question for me regarding whether or not SAL-related dynamics are even factored into the models. It seems that TPC keeps putting "X" 's on their chart for early chances for development based almost purely upon the models. In fact (oddly enough...) it appears to be the CMC, whether by coincidence or not.   When that model closes off isobars and then tracks a hornet sting west, it's been automatic on TPC web-page.  

Anyway, they've had to wipe those off the chart when the model(s) summarily stop developing, and in each case I've noticed that clusters associated with the target disturbances/TW's were demolished by SAL entanglements.   There is still SAL preponderant out there ...just wonderin' if this goes like so many before. Just adding caution to Scott's thing -

Caution IS Scott's "thing"... :lol:

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2 hours ago, CoastalWx said:

I would advise big caution with the GFS. The GFS has been generating just absurd amounts of PWATs that may be causing it to go James from latent heat due to convection. The NHC was actually against the GFS upgrade because of this from what I gather. It sounds like a really bad issue. 

They called it "unacceptable" when recommendations were opened up to the various branches of the NWS.

Sadly, the biggest loss of skill was in the short to medium range track/intensity errors in the Atlantic Basin. And not like small degradation, but like 10% loss of skill.

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3 hours ago, Damage In Tolland said:

Seems Franklin is going to be paying SNE a visit 

Kev = Franklin the weather turtle

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I know, I know "exclusive to SNE"
With this lead time anything is possible. 12z GFS has 0.0001% chance of being correct.
When I see a 930 something sitting off the Space Coast inside d10 it piques my interest more then when living in SNE.

I wonder and maybe someone could answer...Do models have topography algorithms programmed in?
Can't go wrong with ensembles this far out...D'oh.   

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1 hour ago, OceanStWx said:

They called it "unacceptable" when recommendations were opened up to the various branches of the NWS.

Sadly, the biggest loss of skill was in the short to medium range track/intensity errors in the Atlantic Basin. And not like small degradation, but like 10% loss of skill.

For them to say that is eye opening.

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8 minutes ago, ROOSTA said:

I know, I know "exclusive to SNE"
With this lead time anything is possible. 12z GFS has 0.0001% chance of being correct.
When I see a 930 something sitting off the Space Coast inside d10 it piques my interest more then when living in SNE.

I wonder and maybe someone could answer...Do models have topography algorithms programmed in?
Can't go wrong with ensembles this far out...D'oh.   

Euro says wut

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27 minutes ago, CoastalWx said:

The Dawn Awakening: Rise of the GFS.

Fahrenheit 451F: The Gulfstream Strikes Back

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