An Atlantic tropical wave worth watching

By: Dr. Jeff Masters , 2:46 PM GMT on October 04, 2009

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A large tropical wave near 9N 40W, midway between Africa and the Lesser Antilles Islands, is generating a considerable amount of heavy thunderstorm activity as it moves west to west-northwest at 15 mph. The wave is under about 10 - 15 knots of wind shear, and this morning's QuikSCAT pass showed a large and disorganized region of converging winds in the region, with top winds of 25 mph. There is very little dry air in the vicinity, and conditions appear favorable for some slow development of this wave. None of the computer models develop the wave, but they do show relatively low wind shear along the wave's path for the next five days. The wave should reach the Lesser Antilles Islands by Wednesday.


Figure 1. The large tropical wave in the middle Atlantic.

In the Philippines, Tropical Storm Parma continues to linger offshore the northern tip of the Philippines' Luzon Island, bringing heavy rain. The storm has been blamed for the deaths of 17 people in the Philippines, but has not not had the devastating impact that was earlier feared. Parma's heaviest rains will stay offshore of the Philippines today (Figure 2).


Figure 2. Forecast rain amounts for Parma for the 24-hour period ending at 06 UTC October 5 (2am EDT Monday). This forecast is based on satellite measurements of Parma's current rainfall rate, plus a projection of the storm's path. Four to eight inches of rain (yellow colors) is expected along the extreme northwest tip of Luzon Island. Image credit: NOAA Satellite Services Division.

Super Typhoon Melor hits Cat 5 strength
Super Typhoon Melor has become the second Category 5 tropical cyclone of the year. Melor is expected to recurve to the north pass just south of the coast of Japan later this week.

Jeff Masters

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AOI/91/XL
MARK
12.8N/43.1W
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***Special*** Graphics Update:
TROPICAL STORM GRACE Storm Track -
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This is from the 00z CMC last night. This model only shows the 0z run.



I know its weird you have to push the previous button to see where it came from but it looks like its coming from the NW Caribbean. Don't know if theyve changed their tune since then. Guess I have to wait til midnight again. Lol.

Link
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See you guys till 2mr morning, been an interesting weekend. While Grace is named first....Henri-wannabe may become the bigger threat. The satellite presentations now showing a line of thunderstorms developing out ahead of the wave indicating some organization is about to occur. 91L likely within 12 hrs if this trend continues.

Out
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Well,time to turn in. Will catch up with you all tomorrow.

Good night.
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Perhaps recon on Tuesday?
Member Since: September 10, 2007 Posts: 0 Comments: 11537
Like a drop of water in a large ocean..one for the archives.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting hydrus:
I made a mistake, it is the bottom left panel. Another observation, the large disturbance east of the Windwards is showing better outflow and has become slightly more organized in the past few frames.


Thats what I thought. The bottom left panel is showing the perennial Colombian low that is there all year round. I do not think that has anything to do with either of the features now East of the Islands.
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Quoting NCHurricane2009:
000
WTNT44 KNHC 050236
TCDAT4
TROPICAL STORM GRACE DISCUSSION NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092009
1100 PM AST SUN OCT 04 2009

CONVECTIVE ACTIVITY ASSOCIATED WITH THE LOW PRESSURE AREA NORTHEAST
OF THE AZORES ISLANDS HAS BECOME BETTER ORGANIZED THIS EVENING. THE
CONVECTION...WHICH HAS SHOWN SOME ORGANIZATION FOR MUCH OF THE
DAY...IS RELATIVELY DEEP AND SURROUNDS AN EYE-LIKE FEATURE THAT HAS
PERSISTED FOR SEVERAL HOURS. THIS IS THE SAME SURFACE LOW PRESSURE
AREA THAT MOVED THROUGH THE AZORES SEVERAL DAYS AGO AND MADE A
COUNTER-CLOCKWISE LOOP. THE LOW...PREVIOUSLY ASSOCIATED WITH AN
OCCLUDED FRONT AND CO-LOCATED WITH AN UPPER LOW...HAS SINCE LOST
ITS FRONTAL STRUCTURE AND IS NOW LOCATED UNDER A FAIRLY UNIFORM
SOUTHWESTERLY UPPER FLOW. IN ADDITION...2210Z ASCAT DATA INDICATED A
VERY SMALL RADIUS OF MAXIMUM WIND...LESS THAN 20 MILES. WITH THESE
STRUCTURAL CHANGES...THE SYSTEM CAN NOW BE CLASSIFIED AS A TROPICAL
STORM.


I guess the NHC was waiting for the surface analyses to dislocate the surface low from the occluded front, and they also seemed to not like it being under an upper low before classifying it (now its under southwesterly flow SE of the upper low).
Since you posted, and bolded, their discussion, you did not need to retype THEIR discussion as yours.
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ESTIMATED MINIMUM CENTRAL PRESSURE 990 MB

EYE DIAMETER 15 NM

MAX SUSTAINED WINDS 55 KT WITH GUSTS TO 65 KT.
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Quoting kmanislander:


The wave near 55W seems destined primarily for SA. The strongest energy with it based upon the 850 mb vorticity is quite far South.

The one further East seems to be the more significant threat IMO
I made a mistake, it is the bottom left panel. Another observation, the large disturbance east of the Windwards is showing better outflow and has become slightly more organized in the past few frames.
Member Since: September 27, 2007 Posts: 1 Comments: 22582
828. beell
Quoting Weather456:


The most interesting of the year. Have to respect what they thought of 90L before.


Grace it is!
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Quoting GeoffreyWPB:
I agree...the NHC did not designate Grace as a hurricane because they are embarrassed. (Apply directly to the forehead)


lol I literally chewed pencil rubber last night.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
I agree...the NHC did not designate Grace as a hurricane because they are embarrassed. (Apply directly to the forehead)
Member Since: September 10, 2007 Posts: 0 Comments: 11537
000
WTNT44 KNHC 050236
TCDAT4
TROPICAL STORM GRACE DISCUSSION NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092009
1100 PM AST SUN OCT 04 2009

CONVECTIVE ACTIVITY ASSOCIATED WITH THE LOW PRESSURE AREA NORTHEAST
OF THE AZORES ISLANDS HAS BECOME BETTER ORGANIZED THIS EVENING. THE
CONVECTION...WHICH HAS SHOWN SOME ORGANIZATION FOR MUCH OF THE
DAY...IS RELATIVELY DEEP AND SURROUNDS AN EYE-LIKE FEATURE THAT HAS
PERSISTED FOR SEVERAL HOURS. THIS IS THE SAME SURFACE LOW PRESSURE
AREA THAT MOVED THROUGH THE AZORES SEVERAL DAYS AGO AND MADE A
COUNTER-CLOCKWISE LOOP. THE LOW...PREVIOUSLY ASSOCIATED WITH AN
OCCLUDED FRONT AND CO-LOCATED WITH AN UPPER LOW...HAS SINCE LOST
ITS FRONTAL STRUCTURE AND IS NOW LOCATED UNDER A FAIRLY UNIFORM
SOUTHWESTERLY UPPER FLOW. IN ADDITION...2210Z ASCAT DATA INDICATED A
VERY SMALL RADIUS OF MAXIMUM WIND...LESS THAN 20 MILES. WITH THESE
STRUCTURAL CHANGES...THE SYSTEM CAN NOW BE CLASSIFIED AS A TROPICAL
STORM.


I guess the NHC was waiting for the surface analyses to dislocate the surface low from the occluded front, and they also seemed to not like it being under an upper low before classifying it (now its under southwesterly flow SE of the upper low).
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Hydrus,

All you need to do is highlight the URL of the page you want to link, hit cntrl C , go to the comment box on WU, type in your comment, click on link, when the box opens up hit cntrl V then click okay.

Post comment after that.
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Quoting beell:
TS Grace Forecast Discussion #1


The most interesting of the year. Have to respect what they thought of 90L before.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
How long do you think it will be before CMISS starts up on Grace's T#s?
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Quoting WeatherStudent:


Remember what followed Vince, Reed?


oOoOo...with stuff still firing down south, thats a scary thought
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820. beell
TS Grace Forecast Discussion #1
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703

WTNT24 KNHC 050236

TCMAT4

TROPICAL STORM GRACE FORECAST/ADVISORY NUMBER 1

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092009

0300 UTC MON OCT 05 2009



TROPICAL STORM CENTER LOCATED NEAR 41.2N 20.3W AT 05/0300Z

POSITION ACCURATE WITHIN 15 NM



PRESENT MOVEMENT TOWARD THE NORTHEAST OR 55 DEGREES AT 22 KT



ESTIMATED MINIMUM CENTRAL PRESSURE 990 MB

EYE DIAMETER 15 NM

MAX SUSTAINED WINDS 55 KT WITH GUSTS TO 65 KT.

50 KT....... 20NE 20SE 15SW 0NW.

34 KT....... 45NE 45SE 40SW 20NW.

12 FT SEAS.. 45NE 45SE 40SW 20NW.

WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL

MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.



REPEAT...CENTER LOCATED NEAR 41.2N 20.3W AT 05/0300Z

AT 05/0000Z CENTER WAS LOCATED NEAR 40.2N 21.3W



FORECAST VALID 05/1200Z 44.0N 18.0W

MAX WIND 50 KT...GUSTS 60 KT.

50 KT... 20NE 20SE 15SW 20NW.

34 KT... 45NE 45SE 40SW 40NW.



FORECAST VALID 06/0000Z 48.0N 16.0W

MAX WIND 45 KT...GUSTS 55 KT.

34 KT... 45NE 45SE 40SW 40NW.



FORECAST VALID 06/1200Z...DISSIPATED



REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 41.2N 20.3W



NEXT ADVISORY AT 05/0900Z



$$

FORECASTER BROWN
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Quoting 1900hurricane:
So now that Grace has been designated, I wonder what her forecast track shall be.


Grace forecast to go NNE, stay west of the British Isles.
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817. ackee
Quoting superweatherman:
I think Grance is a Hurricane but the NHC are sooo embarance that they did not call it that they have it at 65 mph. You can see it has an eye.
agree
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Quoting hydrus:
To be honest Kman, I do not know how to link yet. I am use to my Tandy 64 K if you get my meaning.:)


Wow, I remember what we used to call the " Trash 80 " LMAO ( as in the Radio Shack TRS 80 model )
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I think Grance is a Hurricane but the NHC are sooo embarance that they did not call it that they have it at 65 mph. You can see it has an eye.
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Ahh, I spoke not a moment too soon!
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Meant JFV didn't have to worry about Grace.
Member Since: September 10, 2007 Posts: 0 Comments: 11537
Quoting kmanislander:


The panels I looked at show the Colombian low. Do you have a link for the CATL with the GEM ?
To be honest Kman, I do not know how to link yet. I am use to my Tandy 64 K if you get my meaning.:)
Member Since: September 27, 2007 Posts: 1 Comments: 22582
Quoting Weather456:


Likely...this is a repost

My track is west to wnw through 3 days, turning a bit more north under the influence of passing trough to the north. This will likely not pick up the system but could influence the ridge currently steering it. The exact timing of these two features will determine how far south/north it gets. My current thinking is between the central lesser Antilles and just north of the Leewards, thus the NE Caribbean, PR, DR and Haiti should monitor this system in the near term.


Thanks. Not Good, is too south and west to miss us. Can Someone turn the Fan ON! Any type of storms are not welcome home.
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Quoting Weather456:
GRACE IS A SMALL TROPICAL CYCLONE. TROPICAL STORM FORCE WINDS
EXTEND OUTWARD UP TO 50 MILES...85 KM FROM THE CENTER.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 990 MB...29.23 INCHES.

...SUMMARY OF 1100 PM AST INFORMATION...
LOCATION...41.2N 20.3W
MAXIMUM SUSTAINED WINDS...65 MPH
PRESENT MOVEMENT...NORTHEAST OR 55 DEGREES AT 25 MPH
MINIMUM CENTRAL PRESSURE...990 MB

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
500 AM AST.

$$
FORECASTER BROWN/FRANKLIN
At least it is moving pretty fast so shouldn't linger anywhere.
Member Since: October 9, 2008 Posts: 0 Comments: 8436
809. amd
Quoting GeoffreyWPB:


Don't worry JFV.


he is most definitely NOT JFV.
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Quoting antonio28:


456 Is this comming our way in the NE caribbean? if Develops?


Likely...this is a repost

My track is west to wnw through 3 days, turning a bit more north under the influence of passing trough to the north. This will likely not pick up the system but could influence the ridge currently steering it. The exact timing of these two features will determine how far south/north it gets. My current thinking is between the central lesser Antilles and just north of the Leewards, thus the NE Caribbean, PR, DR and Haiti should monitor this system in the near term.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Member Since: June 28, 2006 Posts: 25 Comments: 8360
806. amd
Quoting Weather456:


Did you know 90L broke away between 0000 UTC last night and 0600 UTC this morning based on SFC analysis.


no i did not. Although on the picture that keeper showed in post 753, I think there was still some interaction between the 90L and the front, as it looked like there was a cloud link on the nw side of former 90L and the front.

But, it is most definitely a separate entity now, and the NHC is sure of it now, which IMO, was why they quickly updated the system once the cloud separation occurred around 8 pm edt.
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It appears that Grace has went through a rapid deepening phase this evening. It has an eye and is now warm core. Ill have an update out shortly.

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Quoting 1900hurricane:
So now that Grace has been designated, I wonder what her forecast track shall be.


Don't worry JFV.
Member Since: September 10, 2007 Posts: 0 Comments: 11537
Not everyday you seen Greenland and Europe on these maps

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting ackee:
the TW near the windward island anyone thinks it will develop or only the wave further west ?


The wave near 55W seems destined primarily for SA. The strongest energy with it based upon the 850 mb vorticity is quite far South.

The one further East seems to be the more significant threat IMO
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801. ackee
Quoting stormwatcherCI:
I think you mean further east.
thanks further east seem like shear is going be low for the TW near WINDWARD TOO


Member Since: Posts: Comments:
GRACE IS A SMALL TROPICAL CYCLONE. TROPICAL STORM FORCE WINDS
EXTEND OUTWARD UP TO 50 MILES...85 KM FROM THE CENTER.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 990 MB...29.23 INCHES.

...SUMMARY OF 1100 PM AST INFORMATION...
LOCATION...41.2N 20.3W
MAXIMUM SUSTAINED WINDS...65 MPH
PRESENT MOVEMENT...NORTHEAST OR 55 DEGREES AT 25 MPH
MINIMUM CENTRAL PRESSURE...990 MB

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
500 AM AST.

$$
FORECASTER BROWN/FRANKLIN
Member Since: July 24, 2005 Posts: 407 Comments: 19076
So now that Grace has been designated, I wonder what her forecast track shall be.
Member Since: Posts: Comments:
000
WTNT34 KNHC 050236
TCPAT4
BULLETIN
TROPICAL STORM GRACE ADVISORY NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092009
1100 PM AST SUN OCT 04 2009

...TROPICAL STORM FORMS IN THE FAR NORTHEASTERN ATLANTIC...

AT 1100 PM AST...0300 UTC...THE CENTER OF TROPICAL STORM GRACE WAS
LOCATED NEAR LATITUDE 41.2 NORTH...LONGITUDE 20.3 WEST OR ABOUT 420
MILES...675 KM...NORTHEAST OF THE AZORES.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting amd:
post 753 shows why the nhc waited so long to name it. In the last couple of frames of that loop, 90L finally breaks away from the front, and as soon as it does, the eye like feature forms.

Hence soon to be tropical storm Grace


Did you know 90L broke away between 0000 UTC last night and 0600 UTC this morning based on SFC analysis.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting ackee:
the TW near the windward island anyone thinks it will develop or only the wave further west ?
I think you mean further east.
Member Since: October 9, 2008 Posts: 0 Comments: 8436
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Taz..just a friendly reminder...you do not have to quote a long post that is just a few posts away just to say...ok thanks. You can just put the post # on and reply.
Member Since: September 10, 2007 Posts: 0 Comments: 11537
Quoting hydrus:
On the four panel model, the bottom right map shows two areas of low pressure moving west toward the Western Caribbean Sea.


The panels I looked at show the Colombian low. Do you have a link for the CATL with the GEM ?
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792. ackee
the TW near the windward island anyone thinks it will develop or only the wave further west ?
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.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
oh well the nhc name want it wants too name


moveing on now
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789. amd
post 753 shows why the nhc waited so long to name it. In the last couple of frames of that loop, 90L finally breaks away from the front, and as soon as it does, the eye like feature forms.

Hence soon to be tropical storm Grace
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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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