97L growing more organized, will bring heavy rain to the Lesser Antilles

By: Dr. Jeff Masters , 3:55 PM GMT on July 19, 2009

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The tropical wave near 12N 52W, about 600 miles east of the Lesser Antilles Islands (97 L), has grown more organized this morning as it tracks west at about 20 mph. This wave is surrounded by an area of very dry air from the Sahara Desert, but 97L has been able to steadily moisten a large region of the atmosphere over the past day, insulating itself from the dry air. This moistening process has been aided by sea surface temperatures (SSTs) that have steadily increased from 26.5°C to 27.5°C, plus the presence of only 10 knots of wind shear. The system now has a small area of intense thunderstorms near its center, with some rotation of the cloud pattern evident at mid-levels of the atmosphere. An upper-level outflow channel has opened to the north, and there is evidence that surface spiral bands are beginning to form. This morning's QuikSCAT pass missed 97L, so we don't know what is happening at the surface.

Wind shear is a modest 10 knots over the disturbance, and is forecast to remain in the moderate 10 - 15 knot range through Monday morning. This should allow further development to occur today, and 97L could be approaching tropical depression strength on Monday as it moves through the central Lesser Antilles Islands. Monday night, shear is expected to rise to 20 - 30 knots, thanks to the presence of a trough of low pressure at upper levels of the atmosphere over the eastern Caribbean. Since 97L is a relatively small system, it is very vulnerable to wind shear. This shear may be able to drive some of the dry air west of 97L deep into its interior, significantly disrupting the disturbance. Shear will remain high along 97L's path through Thursday, when the storm should be in the western Caribbean near Cuba. If there is anything left of 97L by then, some development is possible. The National Hurricane Center gave 97L a low (less than 30% chance) of developing into a tropical depression in the next 48 hours in their 8am Tropical Weather Outlook. However, I'd say the odds are now in the medium range (30 - 50%).

None of the computer models are forecasting tropical storm development over the next seven days.


Figure 1. Current satellite image of African wave 97L.

I'll have an update Monday morning. As 97L approaches the islands, you may want to follow local observations there using our wundermap for 97L.

Jeff Masters

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Quoting hurricane23:
Cloud tops over the past 2hrs or so have warmed.

Hi 23. What do you think of the system?
Still looking pretty good on Shortwave.
Link
Member Since: July 11, 2006 Posts: 14 Comments: 11351
Looks to be waning a bit at D-Min.
Link
Member Since: July 11, 2006 Posts: 14 Comments: 11351
Quoting sporteguy03:

Hopefully you can give us some observations from there :)


Will do........
Member Since: July 8, 2007 Posts: 0 Comments: 147
Quoting Weather456:


much of my thoughts remain unchange from this morning

To summarize today, the disturbance has been organzing for most of the day, and I suspect QuikSCAT will reveal something close to a LLC. I do believe that the GFS is a tad overdoing the near but since the 12Z run it seems it has trended downwards. Convection has wane along the system this evening likely due to the DMIN suggesting the system is still in the developing stages. the best bets for a code orange/red or TD is Monday morning during the next DMAX. Shear as I said is probablamatic so we have to see.


The storm has slowed somewhat, since it shoudl a bit ways by the islands by now. This timing is critical since some models show the TUTT lifting.

I'm confident that the storm will continue west then eventually turn wnw. If shear does hinder the storm in the SE Caribbean, according to what degree, the storm should be watch in the central caribbean, and the crazy THCPP in the W Carib later this week. 97L is not dead yet so I think the W carib should watch this. Too early to say about the Gulf coast of USA and Mexico.

What sort of effects could Jamaica be looking at?
Member Since: May 16, 2009 Posts: 1 Comments: 1231
yea Dmin has hit it like it did last night, but it has good structure

not sure what the NHC will do at 8pm, I think it will stay yellow though, but we will see
Right-O Sporteguy...less than 30% chance of tropical storm within 48 hours...at least as of 2 p.m. We'll see what they say at 8 pm!
When should it begin to affect The Lower Antilles?
Member Since: July 11, 2006 Posts: 14 Comments: 11351
Quoting Seflhurricane:
weather whats up can you give us a quick synopsis of 97L to answer so the questions being asked here tonight and what might happen ? :)


much of my thoughts remain unchange from this morning

To summarize today, the disturbance has been organzing for most of the day, and I suspect QuikSCAT will reveal something close to a LLC. I do believe that the GFS is a tad overdoing the near but since the 12Z run it seems it has trended downwards. Convection has wane along the system this evening likely due to the DMIN suggesting the system is still in the developing stages. the best bets for a code orange/red or TD is Monday morning during the next DMAX. Shear as I said is problematic so we have to see.


The storm has slowed somewhat, since it should a bit ways by the islands by now. This timing is critical since some models show the TUTT lifting.

I'm confident that the storm will continue west then eventually turn wnw. If shear does hinder the storm in the SE Caribbean, according to what degree, the storm should be watch in the central caribbean, with the crazy THCP in the W Carib later this week. 97L is not dead yet so I think the W carib should watch this. Too early to say about the Gulf coast of USA and Mexico.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting plywoodstatenative:
cowboy, do you have any buoy's in the area?


I think Drak or 456 were saying earlier there were a few in the area, but maybe further north from the system. I haven't looked. Here's the link. The National Buoy Data Center.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
Cloud tops over the past 2hrs or so have warmed.
Member Since: Posts: Comments:
Quoting STORMMASTERG:
Link Again here is wrf/this solution i am buying over gfs.


Wow that shear map doesn't show that much bad shear... it looks like it the shear just kinda moves forward as the storm will probably move just behind it.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
97L doesnt look so great right now :( I hope we get some rain and thunder
Member Since: Posts: Comments:
Weather456 due you think this wrf run could happen? Link
I just looked at that, so if and I mean IF the WRF is correct on shear, 97L will most likely become Ana. This is a long shot though and needs more model support for lower shear. 97L doesn't look so hot, looks like DMIN is beating it down. However, there is still a chance DMAX might get it going again, though I believe the yellow alert stays on the next TWO, and maybe some GFDL and HWRF :)
Member Since: Posts: Comments:
cowboy, do you have any buoy's in the area?
Member Since: November 15, 2005 Posts: 16 Comments: 4189
1201. sporteguy03
10:31 PM GMT on July 19, 2009
Quoting gwadaman:
Good afternoon to all.First time on for the season. I Relocated back to Barbados from Guadeloupe in November and it seems we will be touched by the first weather for the season. Tonight should prove to be interesting for 97L (TD)in my opinion.........only time will tell, non the less we will be in for some heavy showers.

Hopefully you can give us some observations from there :)
Member Since: July 7, 2005 Posts: 0 Comments: 5351
1200. BurnedAfterPosting
10:31 PM GMT on July 19, 2009
Quoting CybrTeddy:


Your right, it does occur 5-10pm EDT, but over there, the sun has set. They're ahead of us.


It is about 9pm there right now, it still has a few hours worth of Dmin to go through

I was refuting the person who said it needed to rebuild convection within the next 2-3 hours for it to survive, that is not the case

It would certainly help its cause though if it did lol
1199. alaina1085
10:30 PM GMT on July 19, 2009
Quoting gwadaman:
Good afternoon to all.First time on for the season. I Relocated back to Barbados from Guadeloupe in November and it seems we will be touched by the first weather for the season. Tonight should prove to be interesting for 97L (TD)in my opinion.........only time will tell, non the less we will be in for some heavy showers.


Welcome back to the blogs. And keep safe.
Member Since: August 2, 2006 Posts: 0 Comments: 1240
1198. CaneWarning
10:30 PM GMT on July 19, 2009
Quoting CatastrophicDL:

Hey Cane, been lurking. I'm here every single day. On vacation right now enjoying the cool mountain temperatures. Posted pictures of yesterday's hike. Good to see you. You know I have to keep an eye on the blog and any potential development :o)


I figured you were off hiking somewhere!
Member Since: April 26, 2009 Posts: 3 Comments: 3667
1197. moonlightcowboy
10:30 PM GMT on July 19, 2009
Plywood, I'm not sure about that, but I think a couple of others have indicated such.


Another thing, dmax could be interesting - not only from more convection firing created from the lift from the greater differences in sfc and atmospheric temps. That could also help to lower pressure and further intensify the system. Yeah, I'd like to see pressure drop some more before I get totally sold on development.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
1196. CatastrophicDL
10:30 PM GMT on July 19, 2009
Quoting CaneWarning:


I haven't seen you in a while!

Hey Cane, been lurking. I'm here every single day. On vacation right now enjoying the cool mountain temperatures. Posted pictures of yesterday's hike. Good to see you. You know I have to keep an eye on the blog and any potential development :o)
Member Since: September 3, 2007 Posts: 3 Comments: 1519
1195. sporteguy03
10:29 PM GMT on July 19, 2009
Quoting Chicklit:
Afternoon Wunderbloggers...
NHC still has 97L on yellow alert which means no tropical storm formation within 48 hours.
Shear above it is quite high, but like Doc Masters says, it is in a nice environment as long as it doesn't go north! I guess we'll see, won't we?

shearmap



Chicklit it means there is less than 30% of TC formation does not mean it can't happen though :)
Member Since: July 7, 2005 Posts: 0 Comments: 5351
1194. gwadaman
10:29 PM GMT on July 19, 2009
Good afternoon to all.First time on for the season. I Relocated back to Barbados from Guadeloupe in November and it seems we will be touched by the first weather for the season. Tonight should prove to be interesting for 97L (TD)in my opinion.........only time will tell, non the less we will be in for some heavy showers.
Member Since: July 8, 2007 Posts: 0 Comments: 147
1193. BenBIogger
10:28 PM GMT on July 19, 2009
Quoting Weather456:


The convection waning may prevent that. the best bets are later Monday morning.


Would encounter strong shear by then
Member Since: March 19, 2009 Posts: 0 Comments: 1421
1192. CybrTeddy
10:28 PM GMT on July 19, 2009
Quoting BurnedAfterPosting:


he is very wrong about that

DMin, and the process of convection waning due to it, occurs between 5-10pm, so no it still has a few hours of dmin and convection does not need to build within the next 2-3 hours for it to have a shot

Dmax is not for another 8 hours or so


Your right, it does occur 5-10pm EDT, but over there, the sun has set. They're ahead of us.
Member Since: July 8, 2005 Posts: 259 Comments: 24181
1191. HurricaneSwirl
10:28 PM GMT on July 19, 2009
Quoting Weather456:


The convection waning may prevent that. the best bets are later Monday morning.


how strong do you expect the shear to be tomorrow for 97L? youve probably got this question tons today.. maybe even by me LOL, so sorry if your repeating yourself a lot.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
1190. weatherwatcher12
10:27 PM GMT on July 19, 2009
Quoting Weather456:


The convection waning may prevent that. the best bets are later Monday morning.

ok
Member Since: May 16, 2009 Posts: 1 Comments: 1231
1189. STORMMASTERG
10:27 PM GMT on July 19, 2009
Link Again here is wrf/this solution i am buying over gfs.
1188. Chicklit
10:26 PM GMT on July 19, 2009
Afternoon Wunderbloggers...
NHC still has 97L on yellow alert which means no tropical storm formation within 48 hours.
Shear above it is quite high, but like Doc Masters says, it is in a nice environment as long as it doesn't go north! I guess we'll see, won't we?

shearmap
Member Since: July 11, 2006 Posts: 14 Comments: 11351
1187. KEEPEROFTHEGATE (Mod)
10:26 PM GMT on July 19, 2009
Quoting weatherwatcher12:

Do you think we will see a TCFA soon
no not at this time
Member Since: July 15, 2006 Posts: 174 Comments: 54398
1186. Cavin Rawlins
10:25 PM GMT on July 19, 2009
Quoting weatherwatcher12:

Do you think we will see a TCFA soon


The convection waning may prevent that. the best bets are later Monday morning.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1185. CaneWarning
10:25 PM GMT on July 19, 2009
Quoting CatastrophicDL:

So true. Felix was a surprise.


I haven't seen you in a while!
Member Since: April 26, 2009 Posts: 3 Comments: 3667
1184. Seflhurricane
10:24 PM GMT on July 19, 2009
Quoting Weather456:
This storm reminds me so much of Felix (not intensity) None of the models develop Felix and there was a toss up with dry air and shear as Felix neared the Antilles.
weather whats up can you give us a quick synopsis of 97L to answer so the questions being asked here tonight and what might happen ? :)
Member Since: July 14, 2009 Posts: 0 Comments: 3022
1183. CatastrophicDL
10:24 PM GMT on July 19, 2009
Quoting Weather456:
This storm reminds me so much of Felix (not intensity) None of the models develop Felix and there was a toss up with dry air and shear as Felix neared the Antilles.

So true. Felix was a surprise.
Member Since: September 3, 2007 Posts: 3 Comments: 1519
1182. alaina1085
10:24 PM GMT on July 19, 2009
Quoting Seflhurricane:
read some of the blog entries back lots of info :)


Thanks, I am. Only missed 10 pages..LOL.
Member Since: August 2, 2006 Posts: 0 Comments: 1240
1181. weatherwatcher12
10:23 PM GMT on July 19, 2009
Quoting Weather456:
This storm reminds me so much of Felix (not intensity) None of the models develop Felix and there was a toss up with dry air and shear as Felix neared the Antilles.

Do you think we will see a TCFA soon
Member Since: May 16, 2009 Posts: 1 Comments: 1231
1180. plywoodstatenative
10:23 PM GMT on July 19, 2009
MLC: MoonLightCowboy
Member Since: November 15, 2005 Posts: 16 Comments: 4189
1179. Seflhurricane
10:23 PM GMT on July 19, 2009
Quoting alaina1085:
So whats going on with 97L now? Is it going to be sheared now or what? Give me the lo down...lol

Thanks guys.
read some of the blog entries back lots of info :)
Member Since: July 14, 2009 Posts: 0 Comments: 3022
1177. CaneWarning
10:22 PM GMT on July 19, 2009
Quoting KEEPEROFTHEGATE:
no 1156 makes it to 61kts 63 kts or more is a cane

winds are under ships dships up to 120- hrs out the rest are long and lat positions


Close enough.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
1176. Cavin Rawlins
10:22 PM GMT on July 19, 2009
This storm reminds me so much of Felix (not intensity) None of the models develop Felix and there was a toss up with dry air and shear as Felix neared the Antilles.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1175. alaina1085
10:22 PM GMT on July 19, 2009
Quoting DestinJeff:
i started a "Dmax / Dmin" drinking game ... i am completely wasted now, and think i may have alcohol poisoning


LMAO.... Best post all day.
Member Since: August 2, 2006 Posts: 0 Comments: 1240
1174. STORMMASTERG
10:21 PM GMT on July 19, 2009
Based on the wrf,shear is will keep on decreasing and weakening and 97l will have favorable condtions from now till july 22.I don't wana go after it.3 is enough for now.
1173. alaina1085
10:21 PM GMT on July 19, 2009
So whats going on with 97L now? Is it going to be sheared now or what? Give me the lo down...lol

Thanks guys.
Member Since: August 2, 2006 Posts: 0 Comments: 1240
1172. KEEPEROFTHEGATE (Mod)
10:20 PM GMT on July 19, 2009
no 1156 makes it to 61kts 63 kts or more is a cane

winds are under ships dships up to 120- hrs out the rest are long and lat positions
Member Since: July 15, 2006 Posts: 174 Comments: 54398
1171. Seflhurricane
10:20 PM GMT on July 19, 2009
Quoting Dar9895:

About those wind shear it will be in Hispaniola so it depends the size and the forward speed.
then why is everyone saying its going to encounter shear very soon ?
Member Since: July 14, 2009 Posts: 0 Comments: 3022
1170. Dar9895
10:19 PM GMT on July 19, 2009
Quoting Seflhurricane:
i truly believe that 97L has a very good shot at becoming a TD soon as for the wind shear i have seen countless of tropical storms and TD that have withstanded 20-30 knots of windshear lets wait and see

About those wind shear it will be in Hispaniola so it depends the size and the forward speed.
1169. Seflhurricane
10:19 PM GMT on July 19, 2009
Quoting KEEPEROFTHEGATE:


WHXX01 KWBC 191813

CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

1813 UTC SUN JUL 19 2009



DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE

AND SUBTROPICAL CYCLONE INFORMATION.



ATLANTIC OBJECTIVE AIDS FOR



DISTURBANCE INVEST (AL972009) 20090719 1800 UTC



...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

090719 1800 090720 0600 090720 1800 090721 0600



LAT LON LAT LON LAT LON LAT LON

BAMS 12.2N 52.5W 13.0N 56.5W 14.6N 60.5W 16.0N 64.5W

BAMD 12.2N 52.5W 12.5N 54.8W 12.9N 57.2W 13.4N 59.7W

BAMM 12.2N 52.5W 12.7N 55.4W 13.5N 58.4W 14.4N 61.4W

LBAR 12.2N 52.5W 12.4N 56.0W 13.0N 59.8W 13.8N 63.7W

SHIP 25KTS 30KTS 35KTS 38KTS

DSHP 25KTS 30KTS 35KTS 38KTS



...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

090721 1800 090722 1800 090723 1800 090724 1800



LAT LON LAT LON LAT LON LAT LON

BAMS 17.8N 68.6W 21.6N 75.7W 24.9N 79.4W 27.5N 79.5W

BAMD 13.9N 62.7W 15.1N 70.0W 16.3N 77.6W 16.6N 84.7W

BAMM 15.4N 64.8W 17.9N 72.3W 20.5N 78.7W 22.1N 83.2W

LBAR 14.9N 67.6W 17.3N 74.6W .0N .0W .0N .0W

SHIP 42KTS 50KTS 56KTS 61KTS

DSHP 42KTS 50KTS 53KTS 58KTS



...INITIAL CONDITIONS...

LATCUR = 12.2N LONCUR = 52.5W DIRCUR = 270DEG SPDCUR = 21KT

LATM12 = 12.4N LONM12 = 48.2W DIRM12 = 270DEG SPDM12 = 20KT

LATM24 = 12.3N LONM24 = 44.2W

WNDCUR = 25KT RMAXWD = 40NM WNDM12 = 20KT

CENPRS = 1012MB OUTPRS = 1014MB OUTRAD = 125NM SDEPTH = M

RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM



$$

NNN

intresting how they bring it up to strong tropical storm
Member Since: July 14, 2009 Posts: 0 Comments: 3022
1167. BaltOCane
10:17 PM GMT on July 19, 2009
Quoting Ossqss:


Seems Mother Nature finds a way when she needs to, no matter what.

L8R Happy Sunday all...


That's a good paraphrase from Jurassic Park.
Jeff Goldblum said it. Right before the dinos went nuts.

Not that I'm making dino-to-hurricane analagies...
Member Since: May 19, 2009 Posts: 0 Comments: 484
1166. CaneWarning
10:17 PM GMT on July 19, 2009
KOG - wow some of those bring it right up to hurricane strength if I read that correctly.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
1165. CUBWF
10:16 PM GMT on July 19, 2009
B

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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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