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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Quoting 1946. twistedfolks:
Well the 8am models are taking 95l more away from the east coast as i thought yesterday.... florida will be saved again


Is that you nostorminflorida?
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Good Morning!
Just a quick drive-by to drop off the GM pic. Couldn't get Dex to stand still long enough for a decent shot of him - very busy under the dock chasing his favorite prey.

7:09 am (11:09 GMT)


The latest GFS SLP run I have from the FSU site is 18z yesterday (Model data last updated Sat Jul 6 23:07:23 UTC 2013). I take it from a quick blog-scan that there's a bit more enthusiasm now?
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Member Since: June 11, 2013 Posts: 20 Comments: 3383
The important thing about the early June 92L and the early July 95L is it will be a long CV season ahead.
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95L HAS TO KEEP THAT BAND OF CONVECTION WEST OF THE LLC
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1948. hydrus
<


Day 1 convective outlook
National Weather Service Storm Prediction Center Norman OK
0737 am CDT sun Jul 07 2013


Valid 071300z - 081200z


..there is a slight risk of severe thunderstorms through tonight for parts of
the central and northern High Plains...


...
The primary belt of westerlies will remain across the northern tier of
states...with one embedded shortwave trough moving eastward over Washington...and
another wave moving eastward over sk/mb. Meanwhile...the earlier closed
low over the MS valley is now a progressive open wave that will
traverse the upper Ohio Valley today. At the surface...the majority
of the Continental U.S. Outside of the northern plains will remain in the warm
sector. Scattered thunderstorms are again expected within the
tropical moisture plume from the northwest/north central Gulf Coast to
PA/NY...and within the residual moisture plume over the central/southern
rockies. The primary risk for organized severe storms today will be
in the upslope flow regime across the central/northern High
Plains...beneath the southern fringe of the stronger middle-upper westerlies.


..central/northern High Plains through tonight...
A surface cold front will drift southeastward across Minnesota through tonight in
association with a weakening lead shortwave trough ejecting east-northeastward
over southern mb. The western extent of the boundary is in the process of
stalling from SW Nebraska to eastern Wyoming and southeast Montana. A corridor of 56-62 f
dewpoints on the cool side of the boundary...as well as stronger
surface heating along and SW of the front...will contribute to
MLCAPE of 1500-2000 j/kg this afternoon in the slight risk area.
This buoyancy...in combination with Ely/southeasterly low-level flow beneath
30-40 knots westerly midlevel flow...will result in a favorable environment
for supercells. Expect new storms to form by early-middle
afternoon...immediately west of the ongoing elevated convection that is
associated with a weak wave moving over central Wyoming...and then spread
eastward/southeastward through the afternoon/evening. The strongest storms will
be capable of producing large hail and damaging gusts...and perhaps
a tornado.


..OH valley region today...
The midlevel low over Illinois/Indiana will evolve gradually into more of
an open wave while moving eastward to western PA/WV by tonight. Though the
low-level reflection of this wave has become quite diffuse...surface
heating in cloud breaks beneath the midlevel cold core will support
scattered thunderstorms today across IL/Indiana/OH. The strongest
storms could produce marginally severe hail and gusty outflow winds.


..Lee of the central Appalachians to New York today...
A persistent belt of clouds/rain is spreading northeastward from eastern Tennessee/KY/WV
toward western PA this morning...in advance of the Ohio Valley midlevel
low. A belt of 35-50 knots southwesterly midlevel flow coincides with the rain
band. Differential heating on the east edge of the thicker clouds will
promote thunderstorm development in a broken band this afternoon
along the terrain gradient from northwest Virginia into central PA...near the east
edge of the somewhat stronger midlevel flow. A few storms in this
corridor could produce isolated damaging outflow winds...given the
moderate midlevel flow and MLCAPE of 1500-2000 j/kg.


..central New York to southern New England today...
An initial cluster of thunderstorms is weakening over east central New York.
However...Richer low-level moisture and stronger surface heating S-west
of this weakening convection could support additional thunderstorm
development by early afternoon. Lapse rates and vertical shear will
be rather modest across this region...which suggests that isolated
strong outflow gusts with multicell clusters will be the main threat
this afternoon.


.Thompson/leitman.. 07/07/2013
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Quoting 1944. CaribBoy:


LLC exposed.. But it looks good though :)

Unless if there's a secondary LLCOC forming
Member Since: June 13, 2009 Posts: 2 Comments: 12822
Quoting 1941. JrWeathermanFL:


I never said 95L wouldn't form, I was nothing the fact that it's convection was weakening and it's center exposed. It might just be temporary but it's happening anyways..


I know you didn't, and I haven't stated I believe 95L would form. ;) Just get a little annoyed at frame-by-frame forecasting. 4-6 hour trends is what I go by.
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LLC exposed.. But it looks good though :)
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Quoting 1931. Grothar:


Not a bad idea people. Take care of yourselves. If I had started eating healthier 100 years ago, I wouldn't be in the position I am now. Thanks, paps. (But you have any more of those muffins??)


But of course! Fresh out of the oven. While I've been blessed with a very healthy cholesterol count all my life, surprises even the doctors, I have a son who was born with three major severe heart defects. He's my miracle boy who only had a ten percent chance of survival before his first surgery. Due to his heart he requires many more calories than the average person, but I've made sure through the years his foods and snacks contained very little junk food. When he buys lunch at work, he buys food like chicken or baked fish, no fast food hamburgers for him! We all need to listen to Grothar about eating healthy as much as we can.
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1942. Grothar
This is a little switch in the models. 12Z

Statistical



Global and consensus

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Quoting 1936. interstatelover7166:
I honestly think we should give 95L a break. It's not even a TD yet. Or maybe not. I think you guys would stick with the latter. :)
Quoting 1933. CybrTeddy:




Patience, storms have faced far worst and developed into far greater.


I never said 95L wouldn't form, I was nothing the fact that it's convection was weakening and it's center exposed. It might just be temporary but it's happening anyways..
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1940. GatorWX
Quoting 1936. interstatelover7166:
I honestly think we should give 95L a break. It's not even a TD yet. Or maybe not. I think you guys would stick with the latter. :)


I just see a circulation, but it's losing convection and is going to have a hard time transitioning away from the itcz with the band of dry air it will move through today.
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Quoting 1933. CybrTeddy:




Patience, storms have faced far worst and developed into far greater.

Agreed

I expect 95L to start dropping its forward speed soon and also it appears to moving more N of due W
Member Since: June 13, 2009 Posts: 2 Comments: 12822
1938. hydrus
95L headed for the Caribbean.
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Quoting 1927. A4Guy:
Anyone see the article in the Sun-Sentinel this morning about the season perhaps not being as active as initially feared? That ought to send some folks on the blog to the ER this morning! :)


I've honestly stopped paying attention to seasonal forecasts after June, all you gotta do is just recall 2012. Most forecasts were at least 6-7 named storms short.
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Quoting 1919. JrWeathermanFL:
Link

If this link works, you can clearly see 95L's circulation coming out from under the convection.
I honestly think we should give 95L a break. It's not even a TD yet. Or maybe not. I think you guys would stick with the latter.... :)
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Quoting 1927. A4Guy:
Anyone see the article in the Sun-Sentinel this morning about the season perhaps not being as active as initially feared? That ought to send some folks on the blog to the ER this morning! :)


As with any mention of a less than explosive season it has already been discounted.
Member Since: September 23, 2005 Posts: 15 Comments: 11501
Quoting 1926. JrWeathermanFL:
95L has been losing some convection in the past frames and the center has become exposed.


Downcasters are getting ready...
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Quoting 1926. JrWeathermanFL:
95L has been losing some convection in the past frames and the center has become exposed.


Quoting 1916. islander101010:
increased the number to two? look at the ir of it. losing convection


Patience, storms have faced far worst and developed into far greater.
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Quoting 1925. Gearsts:
July 7 just saying


Endeed
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1931. Grothar
Quoting 1893. aislinnpaps:


Since Grothar's heart attack I've been doing breakfasts half and half, half heart healthy and half sweet and not really healthy. We all need our strength to keep up with the blog and weather. *G*


Not a bad idea people. Take care of yourselves. If I had started eating healthier 100 years ago, I wouldn't be in the position I am now. Thanks, paps. (But you have any more of those muffins??)
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Quoting 1919. JrWeathermanFL:
Link

If this link works, you can clearly see 95L's circulation coming out from under the convection.

Not really it just look like a bit of the convection waining
Member Since: June 13, 2009 Posts: 2 Comments: 12822
1929. GatorWX
Quoting 1919. JrWeathermanFL:
Link

If this link works, you can clearly see 95L's circulation coming out from under the convection.


That's what I was seeing too, posted on last page.
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1928. Gearsts
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1927. A4Guy
Anyone see the article in the Sun-Sentinel this morning about the season perhaps not being as active as initially feared? That ought to send some folks on the blog to the ER this morning! :)
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95L has been losing some convection in the past frames and the center has become exposed.
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1925. Gearsts
Quoting 1921. CaribBoy:
Always the same problem with CATL waves ... dry air + fast forward speed.

Remember 2012 Ernesto, DT7 and Isaac when they were in the CATL or close to the Antilles. All were fairly pathetic.
July 7 just saying
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Quoting 1918. nrtiwlnvragn:
2012 HWRF and GFDL now close, both dissipate in the Central Carribean:







2013 HWRF dissipates sooner:



Pathetic.
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1923. Gearsts
Center going to be exposed soon
Link
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1922. Grothar
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Always the same problem with CATL waves ... dry air + fast forward speed.

Remember 2012 Ernesto, DT7 and Isaac when they were in the CATL or close to the Antilles. All were fairly pathetic.
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Quoting 1903. ncstorm:
I just saw the 00z CMC run..

I dont know why it mostly aims for the carolinas..it just needs to pack its bags and rent a time share here since it constantly tries to make a trip here


CMC = Constantly Mocking Carolina's
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Link

If this link works, you can clearly see 95L's circulation coming out from under the convection.
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2012 HWRF and GFDL now close, both dissipate in the Central Carribean:







2013 HWRF dissipates sooner:

Member Since: September 23, 2005 Posts: 15 Comments: 11501
Quoting 1913. CybrTeddy:
The T# are meaningless without a closed circulation.

I think it has one or close to one
Member Since: June 13, 2009 Posts: 2 Comments: 12822
increased the number to two? look at the ir of it. losing convection
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1915. ncstorm
CMC Ensembles long range..



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Quoting 1910. CybrTeddy:
The wave train keeps on trucking out new waves.


Yes. Early start to the CV season looks to be underway.
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The T# are meaningless without a closed circulation.
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Quoting 1884. JrWeathermanFL:
95L looks fair this morning. It's in and going toward dry air, moving way too fast and doesn't have a closed LLC. It probably will become a TD, but no more than a TS if it doesn't slow down or hit Hispaniola. Moving at 25 mph is too fast for major development and the mountains of DR weaken most anything that brushes there. I wouldn't be suprised if it makes it to the East Coast, but it won't be strong UNLESS those things mentioned happen.

In other news, I see 94L is gone, and there's some good waves behind 95. The CV season has begun and it's spinnin off some good ones for bein the first week of July.


Good info Jr....... or it's gonna slow down, crawl under Cuba, shoot the gap between Cuba and Mexico and head towards the Gulf Coast as a Cat 2-4! IMPENDING DOOM ALERT!
Member Since: May 13, 2008 Posts: 0 Comments: 1414
1911. pcola57
Quoting 1905. nrtiwlnvragn:


Go to your blog page, "Edit Blog Profile", set "Viewing Comments:" to Show All then Update Blog Profile.


Thank you nrtiwlnvragn and good morning..
That fixed perfectly..
It has happened before long ago and I had forgotten how to correct it..
I wonder what makes it do that anyway?
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The wave train keeps on trucking out new waves.
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NHC can release a Special Tropical Weather Outlook if needed anytime.
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1908. Grothar
Quoting 1898. pcola57:


Yes, it has been happening the past few days.
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See post 1905 :)
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1906. barbamz
For all, who may be interested while waiting for development with 95L: Prof. Petley on his landslide blog is still analysing the catastrophic nightmarish floodings in North India earlier (several posts in the last weeks), and now he has some new impressive videos on what has happened at this pilgrimage location Kedarnath. - I have to go for now, bye bye.

6 July 2013
Videos of Kedarnath on the day of the disaster, and in the aftermath, including a video of the disaster as it happened
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Quoting 1892. pcola57:
Ok...
Once again I've got "Average" showing and I made no selection..
Anybody else getting that and know what to do about it??


Go to your blog page, "Edit Blog Profile", set "Viewing Comments:" to Show All then Update Blog Profile.
Member Since: September 23, 2005 Posts: 15 Comments: 11501
HERE WE GO!! maybe adding invest 96L SOON
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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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