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Atlantic Tropical Action 2013


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Excellent article on chron.com asking what were you doing this morning 30 years ago? There are many color and B & W photos that give an account of what those of us that experienced Alicia were going through at this hour 30 years ago.

 

 

 

What were you doing the morning of Aug. 18, 1983? Assuming you were living here or even alive then, of course.It was then when Hurricane Alicia came ashore southwest of Galveston, packing winds of 115 mph. From there, the eye of the Category 3 storm tracked north-northwest through Houston. When all was said and done the storm was responsible for 21 deaths, $2.6 billion in damages, 23 tornadoes and the end of Brownwood subdivision in eastern Harris County.Unlike Hurricane Ike, Alicia wasn’t one of these storms that formed weeks before and moved across the Atlantic and Caribbean before targeting the Texas coast. This storm formed on Aug. 15 south of New Orleans in the north-central Gulf and tracked to the west-northwest until landfall.Generally, the National Weather Service received high marks for its response to the hurricane. As it neared the Texas coast, the weather service, for the first time, issued probability forecasts for landfall.

http://blog.chron.com/bayoucityhistory/2013/08/30-years-ago-a-hurricane-named-alicia/#15034-2

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Excellent article on chron.com asking what were you doing this morning 30 years ago? There are many color and B & W photos that give an account of what those of us that experienced Alicia were going through at this hour 30 years ago.

 

attachicon.gif08182013 Alicia Alicia_17_aug_1983_2116Z.jpg

 

 

http://blog.chron.com/bayoucityhistory/2013/08/30-years-ago-a-hurricane-named-alicia/#15034-2

 Reports hours old from Galveston.  Northeast wind and coldest beach water I have ever felt there in the month of August.  And the trout are biting.  Not that I caught one.  Big trout.  Live shrimp under a float or 'cork'.

 

Still bumming ex-92L doesn't even look like a rain maker.

 

 

12Z GEFS at 1004 mb or below don't look particularly enthusiastic about 94L.  They get much more enthusiastic in 9 or 11 days for something coming off Africa.  Educated guess it is the blob near 15E.  At 1008, one can see GEFS has a few members showing 94L but losing it, shows a bit more love for the next disturbance, than really likes whatever is coming off the coast in about 9-11 days.  Enough love some members have a closed 1004 mb still over Africa pushing offshore.  At 300 hours, wave after 94L has a little ensemble love, but check out what came off Africa a couple of days before.

post-138-0-80970600-1376854923_thumb.gif

post-138-0-82721100-1376855253_thumb.gif

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Those are tropical models.  Like all models, they have their good points and bad points.

 

 

They're statistical intensity models. All intensity models are bad, but the statistical models remain superior to the dynamic models (for systems with advisories already started).

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I created an image of the African waves that spawned the classics in the last 33 years.

 

attachicon.gifcv.png

 

I see somebody has been using my website ;)

 

http://www.atmos.albany.edu/student/ppapin/gridsat.html

 

For those curious, there are going to be some substantial upgrades in the near future, including IBTrACS integration and additional basins of climatological satellite data. Should be a nice tool for those interested in comparing storms via satellite imagery from the past 30+ years. 

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I see somebody has been using my website ;)

 

http://www.atmos.albany.edu/student/ppapin/gridsat.html

 

For those curious, there are going to be some substantial upgrades in the near future, including IBTrACS integration and additional basins of climatological satellite data. Should be a nice tool for those interested in comparing storms via satellite imagery from the past 30+ years. 

Hey phil I was useing it earlier today looking back at 2004 canes. Question how far back are you gonna add satellite imagery? Also would like the ability to view stills. I for one really enjoy looking at back old models/satellite data for old historic storms. One last request can you add closer views to the SW atlantic bahamas area and possibly visible sat. Either way thanks for putting this together its a great resource.

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VERY nice Phil! Is there any way to identify any of the storms in the loops, or at least a list by year and month of TS and hurricanes?

 

Thats coming in the very near future with the IBTrACS integration which should provide the storm track and name overlaid on the satellite image. There will also be another option to create loops by selected dates or even perhaps by storm name and date (rather than in monthly chunks like I current have provided). When I get a little bit more free time I'll be able to make these upgrades.

 

Hey phil I was useing it earlier today looking back at 2004 canes. Question how far back are you gonna add satellite imagery? Also would like the ability to view stills. I for one really enjoy looking at back old models/satellite data for old historic storms. One last request can you add closer views to the SW atlantic bahamas area and possibly visible sat. Either way thanks for putting this together its a great resource.

 

Well right now it goes back to 1980 which is the beginning of the GridSat Archive thats avilable at NCDC . There was just a recent update that makes the satellite archive current up to the end of 2012 so my next update will include satellite imagery available from 2010-2012. In order to view and save previous satellite images you can just right click on the loop image and "open in new tab" in which the image should be opened up separately from the loop. However, if possible, please save the image for your own connivence before uploading and DON'T hot-link my individual images because that could reduce the bandwidth I have available. 

 

Again this is just the first version of the satellite page, and I have other work I need to get done before I can update the gridsat grid page. Hope you guys enjoy what is there so far though.

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I see somebody has been using my website ;)

 

http://www.atmos.albany.edu/student/ppapin/gridsat.html

 

For those curious, there are going to be some substantial upgrades in the near future, including IBTrACS integration and additional basins of climatological satellite data. Should be a nice tool for those interested in comparing storms via satellite imagery from the past 30+ years. 

I wasn't aware that was your website, Phil! Very nice!

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If you understand the basic dynamics of tropical waves, you can understand why you would expect to see a SAL surge in advance of an AEW that emerges off the African continent.

 

AEW are baroclinic disturbances traditionally over Africa, in which a strong thermal gradient between the moist and cool tropics (Equator to 10N) and the Sahara (15N and above) establishes an easterly jet via thermal wind balance. However, this jet is hardly steady and occasionally you get jet breakdowns as the result of baroclinic instability. The AEWs are the result of these jet breakdowns, where a surge of southeasterlies typically occurs before the wave axis (which causes dust to blow off Africa from the Sahara to the north). As the wave passes by, these winds shift to southeasterly or even southerly with strong waves, which explains why you then see a repireve in the dust plume that moves off Africa, since the air is originating over the tropics and not the Sahara. 

 

Thus, even though Erin "appeared" to have diminished the dust produced from the initial surge before the wave exited Africa, it was only a matter of time till the next south easterly wind surge would take place, producing another SAL outbreak.

 

Enhanced precipitation ahead of a wave emergence can mitigate the amount of dust that blows off Africa, but that can be relatively difficult to predict reliably. In this case, 94L certainly will struggle against this recent SAL outbreak, and doesn't appear to be very convectively active right now. 

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What are you talking about? I thought Erin was clearing the way for all teh stormz?

 

 

I certainly was hoping. Hoping 92L would be a depression soaking the lawn, hoping Erin was giving her life for the season.  Depressing week.

 

 

I remember late July when supposedly mid-August would be the beginning of the real season.

 

18Z GEFS  a little more optimistic on disturbance going feet wet on the 22nd or 23rd between 94L than 12Z GEFS were, neither 12Z nor 18Z gung-ho on 94L, and mondo disturbance coming off about the 28th still looks like a go.  Happiest I've seen the GEFS in a long time by Labor Day Weekend, but the signal is there for nothing until almost the end of the month, and that closer to Africa than North America.

 

So, short term pessimism.  18Z GEFS means and spreads at 2 weeks shows very flat heights, with just a hint of an Ohio Valley trough, with the spreads suggesting the exact location of the trough the area of disagreement, but except for where ensemble spaghetti is showing TCs, South of about 30N, spread is pretty mild, so pessimism is just for August, natural Sunny optimism for Florida and the East Coast in September, still present.

 

500 mb spaghetti shows more than a few TCs and more than a few troughs way back into the Ohio Valley and Lakes.

post-138-0-46318600-1376883348_thumb.gif

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If you understand the basic dynamics of tropical waves, you can understand why you would expect to see a SAL surge in advance of an AEW that emerges off the African continent.

 

AEW are baroclinic disturbances traditionally over Africa, in which a strong thermal gradient between the moist and cool tropics (Equator to 10N) and the Sahara (15N and above) establishes an easterly jet via thermal wind balance. However, this jet is hardly steady and occasionally you get jet breakdowns as the result of baroclinic instability. The AEWs are the result of these jet breakdowns, where a surge of southeasterlies typically occurs before the wave axis (which causes dust to blow off Africa from the Sahara to the north). As the wave passes by, these winds shift to southeasterly or even southerly with strong waves, which explains why you then see a repireve in the dust plume that moves off Africa, since the air is originating over the tropics and not the Sahara. 

 

Thus, even though Erin "appeared" to have diminished the dust produced from the initial surge before the wave exited Africa, it was only a matter of time till the next south easterly wind surge would take place, producing another SAL outbreak.

 

Enhanced precipitation ahead of a wave emergence can mitigate the amount of dust that blows off Africa, but that can be relatively difficult to predict reliably. In this case, 94L certainly will struggle against this recent SAL outbreak, and doesn't appear to be very convectively active right now. 

How much do the Ethiopian Highlands, such as Ras Dashan, play a role in the easterly jet?

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With the 25 year anniversary of Gilbert coming up in three weeks, one of the most remarkable things about the storm was that as it was bisecting Jamaica, the eye became ragged. Within one or two satellite frames of it emerging off the west coast of Jamaica, the satellite image of the eye improved, pretty remarkable.

 

What was the peak wind gust at Grand Cayman island, because I remember as the storm approached, there was concern that Gilbert would totally destroy the island. 

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If you understand the basic dynamics of tropical waves, you can understand why you would expect to see a SAL surge in advance of an AEW that emerges off the African continent.

 

AEW are baroclinic disturbances traditionally over Africa, in which a strong thermal gradient between the moist and cool tropics (Equator to 10N) and the Sahara (15N and above) establishes an easterly jet via thermal wind balance. However, this jet is hardly steady and occasionally you get jet breakdowns as the result of baroclinic instability. The AEWs are the result of these jet breakdowns, where a surge of southeasterlies typically occurs before the wave axis (which causes dust to blow off Africa from the Sahara to the north). As the wave passes by, these winds shift to southeasterly or even southerly with strong waves, which explains why you then see a repireve in the dust plume that moves off Africa, since the air is originating over the tropics and not the Sahara. 

 

Thus, even though Erin "appeared" to have diminished the dust produced from the initial surge before the wave exited Africa, it was only a matter of time till the next south easterly wind surge would take place, producing another SAL outbreak.

 

Enhanced precipitation ahead of a wave emergence can mitigate the amount of dust that blows off Africa, but that can be relatively difficult to predict reliably. In this case, 94L certainly will struggle against this recent SAL outbreak, and doesn't appear to be very convectively active right now. 

do any of the models take SAL outbreaks into account, or is it more that the models simulate SAL via lower humidity areas?

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