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Atlantic Tropical Action 2011 - Part III

HurricaneJosh

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HurricaneJosh

HurricaneJosh

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A new wave has splashed into the E Atlantic riding along 10N. It has gained a pouch designation of P15L...

SYNOPSIS 2011081000

P15L

11N, 10W

700 hPa

ECMWF: After moving off of Africa and weakening slightly, P15L then intensifies into the strongest storm of the season so far. It maintains at least 15 degrees separation to the southeast of P14L/92L.

GFS: Gradually intensifies.

UKMET: Faster than other models, and UKMET does not intensify P15L much.

NOGAPS: OUTLIER! P15L crawls off the African coast and eventually dissipates, becoming only an OW max after 84 hours.

HWRF-GEN: Similar to ECMWF. The only difference is that at later periods, HWRF-GEN depicts a much smaller, compact area of high OW values close to the center of a large pouch.

ECMWF -7.3 v700 & TPW 120h

GFS -7.6 v700 & RH/TPW 120h

UKMET -8.4 v700 & RH 120h

NOGAPS -4.3 v700 108h

HWGEN -6.6 v700 & RH 120h

I like this one much more than the others-- its compactness and low latitude.

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GaWx

GaWx

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By the end of August the GFS is showing about as big a pattern shift possible....Huge high ancored off the NE U.S coast.

This is very much a fwiw as it obviously will almost definitely be a lot different on the next run. However, I do think that looking at these 12z gfs maps is a good way to illustrate a rather typical setup that is conducive for getting major H's deep into the SE US. This run shows 500 mb winds stretching from the SW US northeastward to well up in E Canada on top of a 500 mb high covering

much of the eastern 1/2 of the US and centered near NJ with a surface high centered near VA. This would provide generally favorable conditions for strengthening along with a general WNWish steering well into the SE (i.e., as opposed to just a scraping of the coast) had there been a TC off the SE US on the map. Past SE H's that traveled well into the SE US include Fran of 1996, Andrew of 1992, Hugo of 1989, Dora of 1964, and Gracie of 1959. All of these were major hits except Dora, which managed to weaken just before hitting NE FL. If you were to look at old maps for these five, you'd see the resemblance to today's 12Z gfs maps. The 18Z will almost surely be a lot different, regardless. I'm mentioning this as only an illustration of a near optimal setup for this kind of thing. fwiw.

By the way, the NAO was pretty solidly positive (intuitive) for these five storms as shown by this:

ftp://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.nao.index.b500101.current.ascii

A +NAO isn't required on the day of hitting, but it seems to help the chances for the right setup and the actual major H hits.

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k***

k***

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This is very much a fwiw as it obviously will almost definitely be a lot different on the next run. However, I do think that looking at these 12z gfs maps is a good way to illustrate a rather typical setup that is conducive for getting major H's deep into the SE US. This run shows 500 mb winds stretching from the SW US northeastward to well up in E Canada on top of a 500 mb high covering

much of the eastern 1/2 of the US and centered near NJ with a surface high centered near VA. This would provide generally favorable conditions for strengthening along with a general WNWish steering well into the SE (i.e., as opposed to just a scraping of the coast) had there been a TC off the SE US on the map. Past SE H's that traveled well into the SE US include Fran of 1996, Andrew of 1992, Hugo of 1989, Dora of 1964, and Gracie of 1959. All of these were major hits except Dora, which managed to weaken just before hitting NE FL. If you were to look at old maps for these five, you'd see the resemblance to today's 12Z gfs maps. The 18Z will almost surely be a lot different, regardless. I'm mentioning this as only an illustration of a near optimal setup for this kind of thing. fwiw.

By the way, the NAO was pretty solidly positive (intuitive) for these five storms as shown by this:

ftp://ftp.cpc.ncep.n...1.current.ascii

A +NAO isn't required on the day of hitting, but it seems to help the chances for the right setup and the actual major H hits.

Do you still have your write-up about SW moving cape verdes? I'd like to take a look at it again.

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Srain

Srain

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My favorite is the new lemon. I feel the mandarin is going to fish. The two other lemons (near the SE USA and SSE of Newfoundland) need to just disappear.

You never know. W of Florida in a few days with a stalled/washed out frontal boundary traveling W under the ridge...

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gil888

gil888

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My favorite is the new lemon. I feel the mandarin is going to fish. The two other lemons (near the SE USA and SSE of Newfoundland) need to just disappear.

18z gfs is amusing. Anyone want to take a guess at our cumulative probabilities on the outlook at 12z tomorrow? :)

the 200 mb pattern for the next 10 days on the ecmwf and gfs is simply to die for if you like hurricanes. :popcorn:

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CUmet

CUmet

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12Z GFS has something interesting, a bit of vorticity from Zombie Emily coming back West, and maybe trying to organize in the Yucatan Channel in 8 days.

This little feature has been present on the GFS runs for quite some time now, and even some of the other globals (ECMWF, UKMET) are picking up some reflection as well. The 00z GFS now shows development into what would probably be a weak TC once it nears the Yucatan channel in a week. This appears to originate from the mid-latitude surface trough with a vorticity max located near 27N/50W. The intriguing thing about this is that this should be in a low-shear environment for the entire duration from where it is now to when it tracks into the NW Carib/GOM, since it'll be embedded in a deep easterly flow at all levels. It may be close to whatever 92L becomes down the road, so whatever interaction happens between the two remains to be seen. It'll be interesting to see what comes out of this sleeper threat.

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GaWx

GaWx

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Do you still have your write-up about SW moving cape verdes? I'd like to take a look at it again.

Looking back all the way to 1851, I found only 25 TS+'s that showed some WSW motion during their early lives in the eastern Atlantic (including just during TD stage), indicative of pretty strong E ATL sfc high pressure to the north. Here are some stats:

1) Out of these 25 WSW movers, 11 (44%) hit the US (all as hurricanes), which is nearly THREE times the 1 in 6 chance for ALL Cape Verde type storms since 1960 (w/# days African coast to US):

- #6 of 1893 (GA/SC) (14)

- #4 of 1947 (FL, LA) (14)

- Able of 1952 (SC) (13)

- Carol of 1953 (ME grazed) (11)

- Donna of 1960 (FL, NC, New England) (12)

- Dora of 1964 (FL) (13)

- Allen of 1980 (TX) (12)

- Hugo of 1989 (SC) (12)

- Fran of 1996 (NC) (14)

- Isabel of 2003 (NC) (15)

- Ivan of 2004 (AL/FL) (16)

The 14 that didn't hit the US:

- #2 of 1927

- Charlie of 1950

- Dog of 1951

- Fox of 1951

- Carol of 1965

- Fran of 1990

- Danny of 1991

- Luis of 1995

- Gustav of 1996

- Ivan of 1998

- Dean of 2007

- Bill of 2009

- Fred of 2009

- Igor of 2010

2) TEN (40% of the 25) hit the US as cat 2+.

3) Of the 11 hits, SEVEN (64%) were major (28% of the 25).

4) Of the 25, TEN (40%) were cat 4+ at maximum strength. EIGHT of these ten (80%) eventually hit the US although not necessarily as cat 4+.

5) Since 1851, only FIVE of the 42 storms (12%) that first became a hurricane east of 40 W (and south of 20N) later hit the US. The amazing thing is that FOUR of these FIVE (80%) were WSW movers in the eastern Atlantic: #6 of 1893, #4 of 1947, Donna of 1960, and Isabel of 2003. (Only storm #9 of 1893 wasn't a WSW mover.) To look at it another way, SEVEN of the 25 WSW movers became hurricanes east of 40W. Of these SEVEN, FOUR (57%) later hit the US as an intact cyclone! Only Fox of 1951, Luis of 1995, and Fred of 2009 didn't. However, as those who were closely following "never say die" Fred in 2009 should recall, the remnant of Fred actually did make it all the way into the SE US. So, only Fox of 1951 and Luis of 1995 (of the seven) didn't make it in some form all the way to the U.S.! Compare this to only ONE of 35 non-WSW movers (3%) doing the same!

So, if a storm becomes a hurricane east of 40W (south of 20N), the chances of an eventual hit on the US are pretty high if it had been an eastern Atlantic WSW mover but extremely low if it hadn't been an eastern Atlantic WSW mover. Therefore, if a storm doesn't move WSW in the E Atlantic and if one wants it to make it to the U.S., your best bet would be if it doesn't become a hurricane by 40W.

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Cheeznado

Cheeznado

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I have not much hope of any Cape Verde storm threatening the US over the next 1-2 weeks- the ridge in the Rockies and the eastern trough show no signs of shifting in the near future on the ensembles or op models- meaning any Cape Verde disturbance would have to stay weak and way south. I hope the overall synoptic pattern shifts by September, August will get more active, but fishes may be the order of the day.

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HurricaneJosh

HurricaneJosh

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I have not much hope of any Cape Verde storm threatening the US over the next 1-2 weeks- the ridge in the Rockies and the eastern trough show no signs of shifting in the near future on the ensembles or op models- meaning any Cape Verde disturbance would have to stay weak and way south. I hope the overall synoptic pattern shifts by September, August will get more active, but fishes may be the order of the day.

What about stuff slipping underneath and impacting MX?

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Ed Lizard

Ed Lizard

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What about stuff slipping underneath and impacting MX?

Second GFS run that breaks off some vorticity from Emily and brings it back towards the Gulf. If there is evenn a weak storm enterng the Gulf as shown, mid-level moisture looks like the only limiting factor, as it is right under an anticyclone per GFS.

2011221go.jpg

post-138-0-34172900-1313060664.gif

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VAwxman

VAwxman

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I have not much hope of any Cape Verde storm threatening the US over the next 1-2 weeks- the ridge in the Rockies and the eastern trough show no signs of shifting in the near future on the ensembles or op models- meaning any Cape Verde disturbance would have to stay weak and way south. I hope the overall synoptic pattern shifts by September, August will get more active, but fishes may be the order of the day.

I tend to agree for now. Gibbs somewhere awhile back showed how years with similar overall patterns like this year's tend to bring about storms that stay out at sea unless they can sneak through the Caribbean (I do recall Allen was one that was on the list), and I think that's what we're facing as far as the mean pattern. Always have to take that kind of a guess with some grains of salt though, since the pattern at the exact time of any storm's arrival can deviate from its overall dominant themes.

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Ed Lizard

Ed Lizard

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Looking at close up vis and bigger picture vis and IR, I am not sure what part of 92L, the Northernmost part, or what is still embedded in the ITCZ, will ultimately develop, and if it is the ITCZ portion, it'll be (as I said in 92L thread) slower to develop and start further South.

I believe I also see the Southern end of the vorticity associated with Zombie Emily starting to come back Westward. As mentioned above, there have been 2 GFS runs now that try to put a piece of Zombie Emily (not sure if NHC would want to name it again when most of what is left of Emily went the other way) into the Gulf. The piece is near 25ºN and between 50 and 55ºW, and looks to be about to make its turn back to the Southwest from almost due South.

post-138-0-56511500-1313074792.jpg

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HurricaneJosh

HurricaneJosh

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my question about the system northeast of the islands near 55w and 25n is if this does strengthen, would it be Emily or would it be a new system. Im going to guess a new system even though this is a peice of Emily but I'm not sure

If it keeps its identity as a discrete system-- no matter how crappy and disorganized it gets-- it retains the same name.

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CUmet

CUmet

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my question about the system northeast of the islands near 55w and 25n is if this does strengthen, would it be Emily or would it be a new system. Im going to guess a new system even though this is a peice of Emily but I'm not sure

It would be a new system. The vorticity max associated with Emily is a completely distinct feature and has moved well off to the northeast already.

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HurricaneJosh

HurricaneJosh

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It would be a new system. The vorticity max associated with Emily is a completely distinct feature and has moved well off to the northeast already.

Ah, OK. So if the system splits into two, the vorticity wins the name-custody battle? :D

(Sorry to y'all if my post above was incorrect. I learn something new everyday.)

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icebreaker5221

icebreaker5221

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I like the look over Africa right now, lots of small convective clusters organizing into larger MCSs:

http://www.nrlmry.navy.mil/nexsat-bin/nexsat.cgi?BASIN=CONUS&SUB_BASIN=focus_regions&REGION=AFRICA&SECTOR=Overview&AGE=Prev&INTERVAL=Most_Recent&SIZE=Full&PRODUCT=ir_color&SUB_PRODUCT=meteo8&PATH=CONUS/focus_regions/AFRICA/Overview/ir_color/meteo8&buttonPressed=Animate&ANIM_TYPE=Instant

I know there's nothing beyond 93L in the models for quite a while, but hey, you never know. A long-lived MCV in the right place at the right time is all it takes. :guitar:

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Srain

Srain

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I like the look over Africa right now, lots of small convective clusters organizing into larger MCSs:

http://www.nrlmry.na...IM_TYPE=Instant

I know there's nothing beyond 93L in the models for quite a while, but hey, you never know. A long-lived MCV in the right place at the right time is all it takes. :guitar:

What I've noticed this season is most of the impressive disturbances crossing Africa have been a touch further S near 10N. That bodes well for long tracking TW's as we head deeper into Cape Verde Season.

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