A Gulf of Mexico and an Eastern Atlantic Disturbance Worth Watching

By: Dr. Jeff Masters , 1:53 PM GMT on July 06, 2013

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A tropical disturbance (designated 94L by NHC on Friday) is over the Western Gulf of Mexico, and is headed north towards the Texas/Louisiana coast at 5 - 10 mph. Satellite loops show a modest area of disorganized heavy thunderstorm activity that has been steadily growing this morning. Wind shear has fallen to the moderate range, 10 - 20 knots, since Friday, and the lower wind shear is likely responsible for the increase in thunderstorm activity. A trough of low pressure over the Western Gulf of Mexico is pumping dry air into the west side of 94L, interfering with development. The disturbance should move inland by Sunday morning, bringing heavy rains of 1 - 3" along the Upper Texas and Western Louisiana coasts through Monday morning. None of the reliable forecast models predict that the disturbance will develop, and the disturbance has only a day over water with marginal conditions for development. In their 8 am EDT July 6 Tropical Weather Outlook, NHC gave the disturbance a 20% chance of developing into a tropical depression or tropical storm by Monday.


Figure 1. The Saturday morning NHC Tropical Weather Outlook shows two "Invests" worth watching: 94L over the Gulf of Mexico (area 1), and 95L over the Eastern Atlantic (area 2.) Both were given 20% chances of developing by Monday. Image credit: NHC.

Cape Verdes tropical wave 95L
As we approach mid-July, it's time to begin turning our attention to tropical waves coming off the coast of Africa. We have our first such system worthy of attention today, a tropical wave designated 95L over the Eastern Atlantic near 8°N 33°W, about 800 miles southwest of the Cape Verde Islands. Satellite loops show a modest area of heavy thunderstorms that is showing a moderate amount of spin. Wind shear is moderate, 10 - 20 knots, and ocean temperatures are warm, 28°C. The 8 am EDT Saturday forecast from the SHIPS model predicted that 95L would encounter cooler waters of 27.5°C over the weekend as it headed west to west-northwest at 15 - 20 mph. Wind shear is expected to remain moderate though Monday, which may allow for some additional organization. However, 95L is embedded in a very large area of dry air associated with the Saharan Air Layer (SAL), and July African waves typically have considerable trouble getting organized in the very dry air of the SAL. The disturbance could arrive in the Lesser Antilles Islands as early as Tuesday. A band a strong upper-level winds associated with the subtropical jet stream is expected to be over the northern islands at that time, and if 95L has penetrated as far north as 15°N latitude by that time, it will have to face very high wind shear of 30+ knots. But if 95L stays farther to the south, wind shear should be lower, giving the storm a better chance of development. None of the reliable forecast models predict that 95L will develop. In their 8 am EDT July 6 Tropical Weather Outlook, NHC gave the disturbance a 20% chance of developing into a tropical depression or tropical storm by Monday.


Figure 2. MODIS image of 95L taken at approximately 11 am EDT Saturday, July 6, 2013. Image credit: NASA.

Elsewhere in the tropics
A large upper-level cold-cored low pressure system a few hundred miles north of Puerto Rico will move west over the next dew days, arriving in the Bahamas by Sunday and South Florida by Tuesday. The models do not show that this low will will acquire a surface circulation, and there is only minimal heavy thunderstorm activity associated with it.

In the Eastern Pacific, Tropical Storm Erick is brushing the southwestern coast of Mexico, and is expected to intensify into a Category 1 hurricane on Saturday afternoon. Erick will bring heavy rains of 3 - 5 inches to Southwest Mexico, but the core of the storm is currently expected to remain just offshore. Erick will likely weaken to a tropical storm on Monday, when it will pass just south of Baja.

Cool San Francisco time-lapse fog video
Videographer Simon Christen has created a spectacular 4-minute time-lapse video of fog rushing in past the Golden Gate Bridge into San Francisco. He writes: ""Adrift" is a love letter to the fog of the San Francisco Bay Area. I chased it for over two years to capture the magical interaction between the soft mist, the ridges of the California coast and the iconic Golden Gate Bridge. This is where “Adrift” was born. The weather conditions have to be just right for the fog to glide over the hills and under the bridge. I developed a system for trying to guess when to make the drive out to shoot, which involved checking the weather forecast, satellite images and webcams multiple times a day. For about 2 years, if the weather looked promising, I would set my alarm to 5am, recheck the webcams, and then set off on the 45-minute drive to the Marin Headlands. I spent many mornings hiking in the dark to only find that the fog was too high, too low, or already gone by the time I got there. Luckily, once in a while the conditions would be perfect and I was able to capture something really special. Adrift is a collection of my favorite shots from these excursions into the ridges of the Marin Headlands."


Video 1. Adrift from Simon Christen on Vimeo.

Jeff Masters

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I'm just glad we have something to track.Feels like I'm in my natural habitat.
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Quoting 297. nrtiwlnvragn:
NOUS42 KNHC 061709
REPRPD
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
0115 PM EDT SAT 06 JULY 2013
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 07/1100Z TO 08/1100Z JULY 2013
TCPOD NUMBER.....13-036 AMENDMENT

I. ATLANTIC REQUIREMENTS....................................AD DED.
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.
3. ADDITIONAL DAY OUTLOOK: POSSIBLE LOW-LEVEL INVEST
IN CENTRAL ATLANTIC NEAR 13.3N 57.3W FOR 09/1200Z.


Lolx1000

Recon prefers 95L than 94L
Member Since: June 13, 2009 Posts: 2 Comments: 12509
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Quoting 292. RTSplayer:
Best frame yet.

94L is organizing as well looks like we are in for some busy times ahead, RTS.
Member Since: June 30, 2013 Posts: 12 Comments: 8682
ITs nice that you took that joke in good spirit wunderkidcayman. now let us look ahead to see if 95L becomes Chantal.
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I'd give 95L 40% at the TWO but I know, and I think we all know, the NHC will give it 30%.
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CMC being its usual self
Member Since: June 13, 2009 Posts: 2 Comments: 12509
NOUS42 KNHC 061709
REPRPD
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
0115 PM EDT SAT 06 JULY 2013
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 07/1100Z TO 08/1100Z JULY 2013
TCPOD NUMBER.....13-036 AMENDMENT

I. ATLANTIC REQUIREMENTS....................................AD DED.
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.
3. ADDITIONAL DAY OUTLOOK: POSSIBLE LOW-LEVEL INVEST
IN CENTRAL ATLANTIC NEAR 13.3N 57.3W FOR 09/1200Z.
Member Since: September 23, 2005 Posts: 14 Comments: 11274
94L RainBow Loop

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Getting som rain today from the outskirts of this ULL
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Quoting 278. SLU:
CMC on board with 95L


The CMC lift it north and eventually when it hit the Lesser Antilles it becomes elongated NE to SW by 72 hours which is really fast. The northern circulation over the Northern Antilles dye of (likely to shear) and the Southern Circulation becomes dominant and track NW/NNW similar to TS Fay to South Florida in response to the Track. Right now I find the 12z models to be off, because the systen has a good chance of developing before it reaches the Caribbean.
Member Since: May 25, 2012 Posts: 0 Comments: 2043
Quoting 289. wunderkidcayman:

Na mate first of all completely different year and month
92L from June this year.

Is that blob in the gulf mad because the attention is focused on 95L?.lol.
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Best frame yet.

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All Tropical Floaters
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The 12z CMC shows a 2008 TS Fay or 2006 Hurricane Ernesto type of path for 95L.
Member Since: June 30, 2013 Posts: 12 Comments: 8682
Quoting 283. Stormchaser2007:
95L actually has surprised me a bit today.

Not only has it tightened up, begun to develop upper level cirrus, and form a convergence band to the east, but there are already hints of it trying to develop new convection under the old canopy.

The massive amount of UL divergence is also impressive since its getting further away from the AEJ.

All in all, while it looks great right now, I do think that it will suffer the same fate as the June 2010 92L.



Na mate first of all completely different year and month
Member Since: June 13, 2009 Posts: 2 Comments: 12509
Quoting 278. SLU:
CMC on board with 95L
It develops the ULL and develops 95L into a T.S and sends it up the west side of F.L.More rain for them.But knowing the cmc...
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That SF fog video was just fantastic, thanks for the post Doc!
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Quoting 275. Hurricanes305:


On the Surface Map you showed earlier the African monsoon trough dive SW into the ITCZ because of the high pressure digging into the deep tropics. Once the ITCZ lifts north that will change and allow the High retreat North and allow TWs to gain latitude before reaching the Greater Antilles.


Yup, 305, probably a climatological thing. I guess what we've been seeing is the aggressiveness, frequency from these early twaves. And, given the high setup in the Atlantic, sure doesn't seem to bode well for fish storms in the near future, unless some deep troughing continues coming off the CONUS east coast.
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Oh boy...

Member Since: June 30, 2013 Posts: 12 Comments: 8682
Quoting 265. stoormfury:
a few days ago I nailed 95L WHEN I SAID AN ACTIVE TROPICAL WAVE WAS SOUTH OF THE CAPE VERDE ISLANDS CARRYING A L;OW OF 1012MB. I WAS ATTACKED BY A BLOGGER WHO I SEE HAS NOW JUMPED ON THE BAND WAGON . I THINK HE IS A KID FROM CAYMAN. I WAS RIGHT AFTER ALL.

Yes I was right I was attacked as well


now my heart is pounding kinda reminds me the feeling ya get when RPGs flyin at ya and bullets flyin over ya head
Member Since: June 13, 2009 Posts: 2 Comments: 12509
95L actually has surprised me a bit today.

Not only has it tightened up, begun to develop upper level cirrus, and form a convergence band to the east, but there are already hints of it trying to develop new convection under the old canopy.

The massive amount of UL divergence is also impressive since its getting further away from the AEJ.

All in all, while it looks great right now, I do think that it will suffer the same fate as the June 2010 92L.


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Quoting 273. moonlightcowboy:


Intensity continues to be a problem with most of the models I think. Some are better at cyclogenesis, others at track, but all seem to be lacking still with intensity forecasts. A few years back the GFDL was supposed to have had some intensity improvements, but seems that has panned out too well either yet.
A lot of these systems didn't originate from warm core systems as well.Especically Micheal so perhaps that why they had a hard time.They had a hard time with Chris as well.
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12z CMC 144 hrs. here comes 95L into the picture.

Member Since: June 30, 2013 Posts: 12 Comments: 8682
95L Storm Relative 1km Geostationary Visible Imagery

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278. SLU
CMC on board with 95L
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Quoting 272. Patrap:
Funny how folks pooh-pooh something they cant fathom, seems they need a Cat 5 to be well, enthused.


Until the CAT 5 hits them and they lose everything that means anything to them.. .
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Maybe a Curtain Alert for 95L is warranted?
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Quoting 267. moonlightcowboy:


Curious, after looking at your Meteosat image, are we seeing these African storms, twaves a bit further south and coming off the coastline there this season? I've never particularly watched where they come off the coast that closely, but seems there a tad south. Maybe a climatological thing right now though too, and they'll edge a bit further north as season progresses. Might be a bad observation as well. :)


On the Surface Map you showed earlier the African monsoon trough dive SW into the ITCZ because of the high pressure digging into the deep tropics. Once the ITCZ lifts north that will change and allow the High retreat North and allow TWs to gain latitude before reaching the Greater Antilles.
Member Since: May 25, 2012 Posts: 0 Comments: 2043
No one said this was going to be Ernesto part Deluxe just that the models saw it as a open wave through out it's life time when that wasn't the actual case in reality.No harm no foul..
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E D I T

Quoting 270. washingtonian115:
I have seen the models do a horrid job with past storms in these last few years.Either they over estimated the strength or under estimated it which is why I like to use my eyes to see what the conditions may look like for a future storm.

Storms the models failed last year..

Leslie,Isaac,Ernesto,Kirk,Micheal T.D 7/Helene.

They either over or under estimated strength of these storms or didn't "see" them at all.


Intensity continues to be a problem with most of the models I think. Some are better at cyclogenesis, others at track, but all seem to be lacking still with intensity forecasts. A few years back the GFDL was supposed to have had some intensity improvements, but seems that hasn't panned out too well either yet.
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Funny how folks pooh-pooh something they cant fathom, seems they need a Cat 5 to be well, enthused.

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I doubt anything ever comes of our little cold-core ULL, but it is neat to watch spinning away nonetheless.

Member Since: June 30, 2013 Posts: 12 Comments: 8682
I have seen the models do a horrid job with past storms in these last few years.Either they over estimated the strength or under estimated it which is why I like to use my eyes to see what the conditions may look like for a future storm.

Storms the models failed last year..

Leslie,Isaac,Ernesto,Kirk,Micheal T.D 7/Helene.

They either over or under estimated strength of these storms or didn't "see" them at all.
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94L is in terrible shape on long range radar. Some of the storms are actually rotating the wrong direction (i.e. clockwise) with respect to the center.
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Quoting 261. AussieStorm:

94L means 94 Lame


It's a biggie, though. And getting bigger. Who knows?

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Quoting 210. hydrus:


Curious, after looking at your Meteosat image, are we seeing these African storms, twaves a bit further south and coming off the coastline there this season? I've never particularly watched where they come off the coast that closely, but seems there a tad south. Maybe a climatological thing right now though too, and they'll edge a bit further north as season progresses. Might be a bad observation as well. :)
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Quoting 246. stormpetrol:
95L looks like it could take a Dean 07 track to me.


we will see. 12z GFS does nothing in terms of development with 95L. With that being said the ridge is not as strong as the one during Hurricane Dean that kept a Major Hurricane west. Wayyy to early to say that
Member Since: May 25, 2012 Posts: 0 Comments: 2043
a few days ago I nailed 95L WHEN I SAID AN ACTIVE TROPICAL WAVE WAS SOUTH OF THE CAPE VERDE ISLANDS CARRYING A L;OW OF 1012MB. I WAS ATTACKED BY A BLOGGER WHO I SEE HAS NOW JUMPED ON THE BAND WAGON . I THINK HE IS A KID FROM CAYMAN. I WAS RIGHT AFTER ALL.
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GFS does have a quick moving trough in 150 hours..
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263. Skyepony (Mod)
95L Interesting animation if you click pic. Not sure if it's the effect of low clouds on the left & high on the right coming together or a glitch that catches my eye.
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invest 95L WILL BE AT 30% AT 2PM
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Quoting canehater1:
Maybe we should Change 94-L to 94-P (for persistence).

94L means 94 Lame
Member Since: September 30, 2007 Posts: 9 Comments: 15962
Rarely, if ever, does a Invest, or TD, or TS, or H, follow another storms path.

One would need the exact climo, and a lot of luck for that ever to happen.

Each is unique, and analogs have to be near the formation Date for any of it to matter.

Which it dosen't.
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Quoting 255. RTSplayer:


I think everyone can do just fine without a category 5 landfall.



Yes, but that may not be the case this season.
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There is a forcefield across Central Texas. Whatever develops, it will be far away from us. Dang precipitation forcefield of CenTex.
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Quoting 256. HurricaneAndre:
What do you think the next winds will be.
A 30kts
B 35kts
C 40kts
D same


On what?
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What do you think the winds will be at the next advisory.
A 30kts
B 35kts
C 40kts
D same
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Quoting 246. stormpetrol:
95L looks like it could take a Dean 07 track to me.


I think everyone can do just fine without a category 5 landfall.
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Quoting 190. BahaHurican:
Well, well, well.... say Tropical rains in TX and out pops Rand... howareya, man?




Hey Baha! Long time... been just lurking a lot as of late.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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