African Tropical Wave 98L Moving Over Cooler Waters

By: Dr. Jeff Masters , 2:23 PM GMT on July 23, 2013

Share this Blog
49
+

A strong and well-organized tropical wave that moved off the coast of Africa on Monday (98L) is located a few hundred miles south of the Cape Verde Islands and is moving west-northwest at 15 - 20 mph. Satellite images show that 98L has a decent amount of spin, but only a modest amount of heavy thunderstorms that have not changed much in intensity or areal coverage this morning. The wave is under a moderate 10 - 20 knots of wind shear, which will tend to allow slow development. A large amount of dry air lies to the north and west of 98L, and this dry air will likely interfere with development later this week. The SHIPS model predicts that wind shear will stay in the moderate range through Saturday. Ocean temperatures are barely adequate for development, about 26.5°C today, and will be below average over the region of ocean 98L will be traversing on Wednesday and Thursday, 25 - 26°C. These temperatures are very marginal for development. The Madden Julian Oscillation (MJO), a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days, does not favor increased chances of Atlantic tropical cyclone formation this week. The reliable computer models for tropical cyclone genesis do not predict that 98L will develop this week. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC gave 98L a 40% chance of developing into a tropical cyclone by Thursday. 98L should maintain a west-northwest track through the week, and may spread heavy rains and gusty winds to the northern Lesser Antilles Islands beginning on Saturday night or on Sunday.


Figure 1. Satellite image of 98L off the coast of Africa taken at 8 am EDT Tuesday July 23, 2013, with a satellite analysis of where dry air is, as well. A large amount of dry air lies to the north and west of 98L, and will likely interfere with development later this week. Image credit: University of Wisconsin CIMSS and NOAA/HRD.

Jeff Masters

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 2728 - 2678

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57Blog Index

I do not see it going back down to 45MPH at all
Member Since: Posts: Comments:
Quoting 2716. Bluestorm5:
Again, Dorian will go into unfavorable SST. 26 Celsius or higher is needed for storm to strengthen. Dorian won't have that for awhile.

Even though I do despise this storm for acquiring the name Dorian in past events we have seen storms intensify over pretty below average waters..like Grace 2009,Ida 2009(In the gulf while sst were in the lower 70's and upper 60's)..Chris 2012.
Member Since: August 14, 2010 Posts: 10 Comments: 17810
"Dorion" is trending on twitter.....

No it's not Dorian misspelled, it's completely different.
Member Since: Posts: Comments:
2725. hydrus
Quoting 2716. Bluestorm5:
Again, Dorian will go into unfavorable SST. 26 Celsius or higher is needed for storm to strengthen. Dorian won't have that for awhile.

That is why I was surprised that they had it at storm strength all the way across the Atlantic.
Member Since: Posts: Comments:
(I moved this comment)

Wow, oh my goodness...The opening of the segment on the Weather Channel is BREAKING NEWS 4th Storm of the Season Tropical Storm Dorian will it threaten the US?

Now I am not dissing them for thinking it could eventually impact the US and for advertising that, but this is such a contrast to how people treated storms in years past such as hurricane Andrew in 1992. Watch how they actually don't say out loud that Andrew could hit South Florida in this clip. Even when it is 615 miles from Miami and heading due West, he uses general terms like "it will be in our neighborhood"...Amazing how times have changed. It's just a simple media technique to get people latched on to a storm thousands of miles away so that they will watch that television station.
img src="">
Member Since: May 12, 2012 Posts: 11 Comments: 2875
2723. Dakster
Quoting 2714. washingtonian115:
Our technology for storms have since improved from 1992..I'm glad..I wish I grew up with all these fancy graphs and charts these kids have now a days.


How do you think Grothar feels? He grew up before fire was invented.
Member Since: Posts: Comments:
Quoting 2713. AussieStorm:
Is the NHC saying Dorian is as good as he's going to get?



Traveling at 21mph.


Kind of unusual knowing that it already surpassed the 5 am forecast peak intensity of 45 mph. It is already a 50 mph storm. I have a feeling that Dorian might have a few more tricks up her sleeve.
Member Since: Posts: Comments:
BULLETIN
TROPICAL STORM DORIAN ADVISORY NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042013
1100 AM EDT WED JUL 24 2013

...FOURTH NAMED STORM OF THE 2013 SEASON FORMS...


SUMMARY OF 1100 AM EDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...14.3N 29.9W
ABOUT 410 MI...660 KM WSW OF THE CAPE VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 21 MPH...33 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
SATELLITE IMAGERY AND DATA INDICATE THAT THE TROPICAL DEPRESSION IN
THE EASTERN TROPICAL ATLANTIC HAS STRENGTHENED THIS MORNING.

AT 1100 AM EDT...1500 UTC...THE CENTER OF TROPICAL STORM DORIAN WAS
LOCATED NEAR LATITUDE 14.3 NORTH...LONGITUDE 29.9 WEST. DORIAN IS
MOVING TOWARD THE WEST-NORTHWEST NEAR 21 MPH...33 KM/H...AND THIS
GENERAL MOTION IS EXPECTED TO CONTINUE DURING THE NEXT COUPLE OF
DAYS.

MAXIMUM SUSTAINED WINDS ARE NEAR 50 MPH...85 KM/H...WITH HIGHER
GUSTS. SOME SLIGHT STRENGTHENING IS POSSIBLE TODAY...FOLLOWED BY
GRADUAL WEAKENING ON THURSDAY AS DORIAN MOVES OVER COOLER WATER.

TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 45 MILES...75 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB...29.59 INCHES.


HAZARDS AFFECTING LAND
----------------------
NONE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...500 PM EDT.

$$
FORECASTER STEWART
Member Since: Posts: Comments:
Quoting floridaT:
this is cool nasa is going to deploy drones to film the storms. story on yahoo


Here is a NASA G+ on it.

Member Since: September 30, 2007 Posts: 9 Comments: 15977
2719. Dakster
Quoting 2702. islander101010:
freshwater florida drains really slow. watching dorian


It doesn't really drain, more like percolates.
Member Since: Posts: Comments:
2718. hydrus
Quoting 2658. Portlight:
Portlight Honored with 1 WTC Flag

Chairman Paul Timmons and New Jersey Portlight Volunteers received a Letter of Appreciation and a Flag that flew over the New WTC 1 in New York Monday morning as a token of their State's appreciation of the work done Post Sandy by Portlight and it's volunteers.
What a great thing...Portlight deserves such an honor for helping so many in terrible conditions.
Member Since: Posts: Comments:
2717. LargoFl
Member Since: Posts: Comments:
Again, Dorian will go into unfavorable SST. 26 Celsius or higher is needed for storm to strengthen. Dorian won't have that for awhile.

Member Since: August 1, 2011 Posts: 28 Comments: 8075
Member Since: March 12, 2013 Posts: 110 Comments: 105715
Our technology for storms have since improved from 1992..I'm glad..I wish I grew up with all these fancy graphs and charts these kids have now a days.
Member Since: August 14, 2010 Posts: 10 Comments: 17810
Is the NHC saying Dorian is as good as he's going to get?



Traveling at 21mph.
Member Since: September 30, 2007 Posts: 9 Comments: 15977
wow!! what is going on here with the east coast all in blue
Member Since: March 12, 2013 Posts: 110 Comments: 105715
ZCZC MIATCDAT4 ALL
TTAA00 KNHC DDHHMM

TROPICAL STORM DORIAN DISCUSSION NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042013
1100 AM EDT WED JUL 24 2013

VISIBLE SATELLITE IMAGERY AND RECENT ASCAT SCATTEROMETER WINDS
INDICATE THAT THE TROPICAL DEPRESSION HAS BECOME BETTER ORGANIZED
AND HAS STRENGTHENED INTO TROPICAL STORM DORIAN. THE INITIAL
INTENSITY OF 45 KT IS BASED ON A 38-KT ASCAT SURFACE WIND AT
1111Z... AND VARIOUS OBJECTIVE SATELLITE INTENSITY ESTIMATES OF
ABOUT 45 KT.

THE INITIAL MOTION ESTIMATE IS 285/18 KT. DORIAN IS EXPECTED TO BE
STEERED WEST-NORTHWESTWARD TO WESTWARD BY A STRONG DEEP-LAYER
SUBTROPICAL RIDGE OVER THE CENTRAL AND EASTERN ATLANTIC. THE NHC
MODEL GUIDANCE REMAINS TIGHTLY PACKED IN EXCELLENT AGREEMENT ON
THIS TRACK SCENARIO...WITH THE ONLY DIFFERENCES BEING SLIGHT
VARIATIONS IN THE FORWARD SPEED. THE NHC OFFICIAL FORECAST TRACK IS
SIMILAR TO THE PREVIOUS ADVISORY AND IS CLOSE TO THE MULTI-MODEL
CONSENSUS TVCN.

FOR THE NEXT 24 HOURS OR SO...THE VERTICAL SHEAR IS FORECAST TO BE
VERY LOW WHILE DORIAN REMAINS OVER MARGINALLY WARM SSTS. HOWEVER...
DURING THE 24-48 HOUR TIME PERIOD...DORIAN WILL BE MOVING OVER 25C
SSTS...WHICH COULD INDUCE SOME SLIGHT WEAKENING. THE CYCLONE IS
EXPECTED TO MAINTAIN THE CURRENT FAVORABLE EQUATORIAL INFLOW OF
WARM UNSTABLE AIR THAT IS OFFSETTING THE COOLER MORE STABLE AIR
BEING INGESTED FROM THE NORTH...AND THAT COULD OFFSET THE EFFECTS
OF DORIAN PASSING OVER COOLER WATERS. FOR THAT REASON...THE
INTENSITY FORECAST ONLY SHOWS SLIGHT WEAKENING AT 36- AND 48-HOURS.
AFTER THAT...THE CYCLONE IS LIKELY TO ENCOUNTER BOTH WARMER WATER
AND INCREASING WESTERLY SHEAR...SO THE INTENSITY FORECAST IS HELD
STEADY. THE OFFICIAL INTENSITY FORECAST IS SLIGHTLY HIGHER THAN THE
PREVIOUS ADVISORY THROUGH THE NEXT 24 HOURS DUE TO THE HIGHER
INITIAL INTENSITY...BUT THEN FOLLOWS THE TREND OF CONSENSUS MODELS.

FORECAST POSITIONS AND MAX WINDS

INIT 24/1500Z 14.3N 29.9W 45 KT 50 MPH
12H 25/0000Z 15.0N 32.6W 50 KT 60 MPH
24H 25/1200Z 15.8N 36.1W 50 KT 60 MPH
36H 26/0000Z 16.4N 39.8W 45 KT 50 MPH
48H 26/1200Z 17.1N 43.4W 40 KT 45 MPH
72H 27/1200Z 18.3N 51.2W 40 KT 45 MPH
96H 28/1200Z 19.3N 58.2W 40 KT 45 MPH
120H 29/1200Z 20.1N 64.0W 40 KT 45 MPH

$$
FORECASTER STEWART

NNNN
Member Since: Posts: Comments:
2710. Gearsts
lol
Member Since: Posts: Comments:
this is cool nasa is going to deploy drones to film the storms. story on yahoo
Member Since: Posts: Comments:
Quoting 2697. K8eCane:
everyone on this blog should know that Dorian is too far away for accuracy right now as to track or strength really
Track is pretty much easy to forecast for next 5 days... after that? Dunno. Strength wise... that'll be interesting.
Member Since: August 1, 2011 Posts: 28 Comments: 8075
2707. K8eCane
Quoting 2701. weatherh98:


but whats the fun if you don't start guessing now:)



key word is guess. Although on this blog there are a lot of EDUCATED guesses. I listen to those
Member Since: Posts: Comments:
WOW! From 35mph to 50mph with gusts up to 60! That is fast intensification. I wonder if it will make it to the SE US. If it intensifies more it should survive the dry air and moderate wind shear.
Member Since: Posts: Comments:
Microwave imagery says Dorian was forming a banding eyewall at 8am EDT. So yes, that feature on satellite is probably the beginnings of an eye.

Member Since: July 6, 2010 Posts: 113 Comments: 32822
Quoting 2680. SPLbeater:


On one hand, I want that to occur to kill the storm and maybe spare the US. But on the other hand...those people down there cant always escape the mudslides...and they certainly dont have much money for repairs.

Recurvature, I pray for!

I guess your prayers have been working the last 4 years...
Member Since: May 12, 2012 Posts: 11 Comments: 2875
The NHC is holding up the advisory, this one should be well detailed I would assume.
Member Since: Posts: Comments:
freshwater florida drains really slow. watching dorian
Member Since: Posts: Comments:
Quoting 2697. K8eCane:
everyone on this blog should know that Dorian is too far away for accuracy right now as to track or strength really


but whats the fun if you don't start guessing now:)
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting 2668. GTstormChaserCaleb:
Confirm what?

You will see

Quoting 2672. LargoFl:
Dorian is coming into view now

yep hopefully SSD will now fix the floater images properly

hey wash wow the blog is moving fast I had to get trough nearly 4 pages to look for that comment you wanted me to fix anyway most of the comment was still valid and we "blog legal" so this is what remains

Quoting 2476. washingtonian115:
Wunderkid I hate to put you down but this isn't headed for the Caymans.Sorry just isn't in Dorian's future..

lol your not PART OF COMMENT REMOVED BY WUNDERKIDCAYMAN I never said it was heading for cayman hell I never even mention the W Caribbean

I said what I said to make a point now wash PART OF COMMENT REMOVED BY WUNDERKIDCAYMAN can you figure out the point I'm making

I hope you can handle this comment
Member Since: June 13, 2009 Posts: 2 Comments: 12716
2699. Grothar
It looks like 98L/Dorian made quite a turn to thw WNW last night. It should be resuming a much more westward movement later


Member Since: Posts: Comments:
Regardless of the retreat of SAL ahead of Dorian, he is still crossing a very dry and stable Atlantic at the moment so he will have to continue and build moisture and convection on his own for the next several days.

Too far out to know what will happen at the end of the current period but his best chances for real intensification might be as he approaches the Bahamas.

Not suggesting that it will happen but just noting the possibilities..........It's going to boil down to how the sheer is looking North of Puerto Rico when he gets there.
Member Since: August 8, 2006 Posts: 0 Comments: 9402
2697. K8eCane
everyone on this blog should know that Dorian is too far away for accuracy right now as to track or strength really
Member Since: Posts: Comments:
...
Member Since: May 12, 2012 Posts: 11 Comments: 2875
2695. junie1
dorian will come to close to me for comfort any shift takes it over the northen islands
Member Since: Posts: Comments:
Quoting 2674. Dakster:


That explains why the high is building back in.





I got it
Member Since: Posts: Comments:
2693. hydrus
Quoting 2650. Hurricanes305:
No hurricane yet... on the 5 day end

I am surprised they have it at storm strength for 5 days straight. Cannot see the storm here, but the predicted track is there.




Member Since: Posts: Comments:




Just hours after Tropical Depression 4 formed in the eastern Atlantic Ocean off the African coast, the system was upgraded to a tropical storm Wednesday morning.

Tropical Storm Dorian is more than 3,000 miles away from the Tampa Bay area, and many things could keep it from becoming a threat to the Caribbean Sea, Bahamas or Florida, Bay News 9 meteorologist Juli Marquez said.
"It's something we will watch for a while," she said.

The storm has sustained winds of 50 mph and has strengthened and become better organized in recent hours. It's centered about 310 miles west-southwest of the Cape Verde Islands, off the coast of west Africa, and is moving west-northwest at 21 mph.

It's expected to move west-northwest for several days.

"There's a big area of high pressure that's very strong," Marquez said. "Basically, it just kind of steers it (west-northwest). It's a long way from Tampa Bay, but it's going to move in this direction and could strengthen a little tonight or tomorrow. It will encounter some cooler waters, a little drier air that it will have to battle.

"The forecast shows it perhaps heading toward the Caribbean, maybe the Bahamas, but that's not until early next week.

Dorian is the fourth named storm of the season.

Link
Member Since: Posts: Comments:
Quoting 2625. unknowncomic:
11AM Ensemble shows recurves.



In the best case scenario this will play out. The problem is the ensembles will change every day trending left then trending right. We just hope for the best and hopefully Dorian won't become a hurricane down the road.
Member Since: Posts: Comments:
Quoting 2677. Grothar:
Why are they late with the advisories?


waiting for new dr masters blog? haha
Member Since: Posts: Comments:
Quoting 2577. Waltanater:
Wow. It may be named in a software tool but it doesn't make it official. The data may be accurate, but the people at the NHC are the ones that make the official announcement to the public. That is what I am referring to.


Do you not see that the link has NHC in it? Do you also see that in the first few lines it says NHC clearly?

It might not show up on NHC's main site, but if it is viewable information that the Public can see, it will be official information. Can't make this anymore clear lol.
Member Since: Posts: Comments:
2686. Grothar
Quoting 2669. CaneHunter031472:


The high will be a big problem this year because of it's intensity. I don't see many fish storms (if any) happening. I wonder if there is any similarity between this year's High and 2005.


Yes there is. The high was expected to build back in strongly from reports at least 5 days ago. I would expect a lot of these storms to possible be Caribbeantrackers or at least remain on very WNW to West tracks.
Member Since: Posts: Comments:
Quoting 2665. CybrTeddy:


Fixed it for ya.
Lol.She'll be coming later in the season to pay a visit to the bloggers here.
Member Since: August 14, 2010 Posts: 10 Comments: 17810
Judging by the high, missing Hatteras and Cape Cod seem unlikely, but things can change
Member Since: Posts: Comments:
2683. Dakster
Quoting 2678. HoraceDebussyJones:


You need to get off the Turnpike honey to see the real Jersey


Does it smell better OFF the turnpike?
Member Since: Posts: Comments:
Quoting 2589. whitewabit:


Aren't they releasing large amounts of water into both rivers out of "O"


yes, but the bottom line is that it can fill faster than they can drain it...
Member Since: Posts: Comments:
Quoting 2676. opal92nwf:

If it goes any farther south it could be another Hispaniola dilemma....


On one hand, I want that to occur to kill the storm and maybe spare the US. But on the other hand...those people down there cant always escape the mudslides...and they certainly dont have much money for repairs.

Recurvature, I pray for!
Member Since: Posts: Comments:
2679. 7544
anyone think dorian will be a hurricane before reaching the islands i do !
Member Since: May 6, 2007 Posts: 0 Comments: 6874
Quoting 2673. NYtampagirl:


How about New Jersey being called "the Garden State"? The pollution there will kill your lungs in about three seconds! the only thing that grows in NJ is toxic waste! And rude people.


You need to get off the Turnpike honey to see the real Jersey
Member Since: Posts: Comments:

Viewing: 2728 - 2678

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

Local Weather

Overcast
26 °F
Overcast

JeffMasters's Recent Photos

Lake Effort Snow Shower Over Windsor, Ontario
Sunset on Dunham Lake
Pictured Rocks Sunset
Sunset on Lake Huron