97L still disorganized, but bringing heavy rains to the northeast Caribbean

By: Dr. Jeff Masters , 12:27 PM GMT on October 04, 2010

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A large region of disturbed weather (Invest 97L) covers the Lesser Antilles Islands and waters near Puerto Rico and the Virgin Islands. The storm is headed west-northwest at about 10 mph, and will bring heavy rain showers and gusty winds to the Lesser Antilles, Puerto Rico, the Virgin Islands, and the Dominican Republic today. These showers can be seen on Martinique radar this morning, and Martinique reported a wind gust of 35 mph this morning during one of 97L's heavy squalls. An upper level trough of low pressure is contributing to the heavy rain showers by making the atmosphere more unstable. This same trough is also bringing moderate wind shear of 10 - 20 knots, which will keep any development today very slow to occur. Recent satellite imagery shows a large area of intense thunderstorms associated with 97L, but the activity is not well organized, and there are no signs of a surface circulation. Long range radar out of Puerto Rico also shows no signs of rotation.


Figure 1. Morning satellite image of Invest 97L.

Forecast for 97L
The SHIPS model predicts that wind shear over 97L will slowly fall over the next three days, reaching the low range, 5 - 10 knots, by Thursday, which may allow the storm to develop into a tropical depression, if its center can stay over water. All of the major computer models now show development of 97L into a tropical depression Wednesday or Thursday, just north of Hispaniola. By Thursday, a passing trough of low pressure is expected to pull 97L to the northeast away from Hispaniola, and rains should end by Friday on the island if this forecast verifies. NHC is giving 97L a 20% chance of developing into a tropical depression by Wednesday. 97L will move at about 5 - 10 mph today through Wednesday, bringing the potential for an extended 3-day period of heavy rains for the islands in its path. These rains may result in life-threatening flash flooding and mudslides in Puerto Rico and the Dominican Republic today through Wednesday, and for Haiti Tuesday through Thursday. Flash flood watches are posted for the Virgin Islands and Puerto Rico today.

Elsewhere in the tropics
An area of disturbed weather near 10N, 47W is under a high 20 knots of wind shear, and is headed northwest into a region of even higher wind shear of 20 - 30 knots. Satellite imagery shows only a limited amount of heavy thunderstorms, and there is plenty of dry air in the vicinity that is interfering with development. NHC is giving the disturbance a 10% chance of developing into a tropical depression by Wednesday.

Most of the models indicate the possibility that a strong tropical disturbance capable of becoming a tropical depression will form in the Central or Southern Caribbean 6 - 8 days from now.

Next update
I'll have an update Tuesday morning.

Jeff Masters

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Invest97L : NHC-ATCF
4Oct 12amGMT - - 17.6n62.8w - - 25knots -- 1007mb -- NHC-ATCF *17.8n63.9w
4Oct 06amGMT - - 17.6n64.1w - - 25knots -- 1007mb -- NHC-ATCF *17.8n65.4w
4Oct 12pmGMT - - 17.6n64.5w - - 25knots -- 1007mb -- NHC-ATCF *17.7n65.4w
4Oct 06pmGMT - - 17.6n64.8w - - 25knots -- 1007mb -- NHC-ATCF *17.7n65.8w
5Oct 12amGMT - - 17.5n64.5w - - 25knots -- 1007mb -- NHC-ATCF
* Before NHC reevaluated&altered the ATCF numbers

Copy&paste 17.6n62.8w-17.6n64.1w, 17.6n64.1w-17.6n64.5w, 17.6n64.5w-17.6n64.8w, 17.6n64.8w-17.5n64.5w, bqn, ngd, gbj into the GreatCircleMapper for a look at the last 24hours.
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Quoting CyclonicVoyage:


Agree there.

97L is showing the game face tonight, IMO.


Still needs some work on the western side, but yes. I agree. I suspect we'll see Otto from this in the next two days.
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Quoting sunlinepr:
For those who don't know this webpage, Interesting; Climatology
of Caribbean Hurricanes
Link
Click any city and you can see a list of all hurricanes that have hit.....

Also Climatology
of Caribbean Hurricanes

Link

The main page is the Caribbean Hurricane Network

Link




Thanks a bunch. I bookmarked that.
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Quoting Orcasystems:
I just got a new Crackberry... so I have been a bit busy. I found a new ring tone for it... SWMBO is having a small problem with it ;)

Ring Tone


And you are still alive?

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Quoting KoritheMan:


Upper low moving NW. Shear should lessen as a result.


Agree there.

97L is showing the game face tonight, IMO.
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Quoting CyclonicVoyage:
Looks to be taking in a bit of shear ATM though.


However, not for long.



Upper low moving NW. Shear should lessen as a result.
Member Since: Posts: Comments:
For those who don't know this webpage, Interesting; Climatology
of Caribbean Hurricanes
Link
Click any city and you can see a list of all hurricanes that have hit.....

Also Climatology
of Caribbean Hurricanes

Link

The main page is the Caribbean Hurricane Network

Link


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Looks to be taking in a bit of shear ATM though.


However, not for long.

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What a great time to look, lol. Next frame of the Sat just updated and it's almost completely covered...
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611. JLPR2
Quoting CyclonicVoyage:
Nope

17.1N 63.2W


Somewhere in that vicinity XD
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Nope

17.1N 63.2W
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609. JLPR2
St. Croix is going to get pounded soon.

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UMM could be 16.9 though.
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Either way it's going, sure looks to be getting it's tropical groove on tonight @ 17.1w 63.1n
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606. JLPR2
getting rounder


Still needs to ditch the tail to the W
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Quoting Orcasystems:
OK, WTF is that "thing" to the east of 97L... the evil face???






LOL

wat
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604. Relix
Quoting CyclonicVoyage:


Arrows are pointing N on the SFWMD site.

Its basically stationary and drifting
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603. JLPR2
Quoting CyclonicVoyage:


Arrows are pointing N on the SFWMD site.


Then it was initialized incorrectly since it ain't that far south.
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Complete Update


AOI
AOI AOI AOI

AOI AOI AOI

TS BUSTED FORECAST ALIBI
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Quoting JLPR2:


The other way, south xD


Arrows are pointing N on the SFWMD site.
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Quoting Orcasystems:
OK, WTF is that "thing" to the east of 97L... the evil face???






I'll take your evil face and up you one giant ULL.
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599. JLPR2
Quoting CyclonicVoyage:
Evening All.

Xtrap has 97L Craaaaawwwwwllling N?



The other way, south xD
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Quoting pottery:

Looks like one of Snake's cats...
look like Casper
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Evening All.

Xtrap has 97L Craaaaawwwwwllling N?

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596. JLPR2
Quoting Relix:


Lol I have a Music class (close to COPU) then gotta walk all the way to get something to eat and the center and then Naturales. It. Will. Be. Hellish! XD!


Just two words for you: Extra Shoes XD LOL!
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Quoting Orcasystems:
OK, WTF is that "thing" to the east of 97L... the evil face???





Looks like one of Snake's cats...
Member Since: October 24, 2005 Posts: 0 Comments: 24055
594. Relix
Quoting JLPR2:


At least all of my classes are in the same building, ha!
Take that nature! XD LOL!


Lol I have a Music class (close to COPU) then gotta walk all the way to get something to eat and the center and then Naturales. It. Will. Be. Hellish! XD!
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OK, WTF is that "thing" to the east of 97L... the evil face???




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Quoting JLPR2:


Pero en Bayamon siempre llueve :P LOL!

Quiet here in Carolina
yes is true but yesterday few rains and a lots of humidity
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Quoting Grothar:
Is this an OOHH or an AHHHH?



More like an ahhhhhh
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590. JLPR2
Quoting Relix:


Intersting.

Tomorrow's gonna be a true mess at UPR JLPR =P


At least all of my classes are in the same building, ha!
Take that nature! XD LOL!
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589. JLPR2
Quoting luigi18:



Hey Bro the rain is pouring down now! Bayamon


Pero en Bayamon siempre llueve :P LOL!

Quiet here in Carolina
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588. Relix
Quoting JLPR2:
Sustained 30mph winds int he buoy to the south of 97L

Tue, 05 Oct 2010 02:50:00 UTC
Winds: SW (220) at 25.3 kt


Intersting.

Tomorrow's gonna be a true mess at UPR JLPR =P
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Quoting JLPR2:
I hadn't seen this, 12z EURO O_O
48hrs


24hrs Possible 1006mb TD in the East coast of PR


Jeez, the EURO is amazing, it developed the low that didn't even exist then.



Hey Bro the rain is pouring down now! Bayamon
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Quoting kmanislander:


If you look at the tracks this season, the vast majority of storms recurved well East of the CONUS. The reason for this is clearly associated with the strong La Nina that developed and the train of troughs that paraded off the East coast one after the other.
Historically, neutral years see more storms track due West. La Nina see more storms recurve.

As for the lower numbers, well it is largely attributed to dry air and shear. The shear forced dry into many fledgling systems disrupting them in the formative stages and preventing several from developing. Those that did took forever to do so.

Consequently, I would summarise this season as being known for three key elements that prevented it from being the " mother of all seasons ".

1. La Nina
2. Dry air
3 Shear

One final note. Why the dry air ??

Remember the jet stream that got locked into the flow pattern that created the fires and record heat in Russia ?. It also created record heat across the CONUS.

That heat inland on the continents created very dry sinking air ( subsidence ) across the Atlantic which in turn suppressed the development of tropical systems. I think that the post season analysis will focus on this as a key element that was not foreseen.


Excellent analysis.... Soon we will add another variable, that will slow down the season; Cold fronts with cooler sea temps...
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585. JLPR2
Sustained 30mph winds int he buoy to the south of 97L

Tue, 05 Oct 2010 02:50:00 UTC
Winds: SW (220) at 25.3 kt

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584. JLPR2
Quoting luigi18:
you thinks is going to be a normal day for us here in PR ?


Well something would have to change dramatically, which is possible, but I don't want to be sleepy if it doesn't.
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tomorrow? no
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Quoting sunlinepr:
Cape Verde season may be over... but African waves are still on the way.... What about that new wave spinnin
at 8N, 30W?? Seems like we will have to take her in consideration...


Hmmm!
Still lots of stuff going on out there.
Neopolitan might be correct. A couple more named systems will change the way things are, big time....
Member Since: October 24, 2005 Posts: 0 Comments: 24055
Quoting JLPR2:
Looking more and more interesting and arrg! And got to be sleeping before 2am :(

you thinks is going to be a normal day for us here in PR ?
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I'm off. My Dolphins have let me down again--go special teams!--and I have an early meeting. Before I go, though, here's a little something for the site's winter lovers:

CAZ519-050715-
/O.CON.KVEF.WW.Y.0017.101005T0500Z-101005T1800Z/
EASTERN SIERRA SLOPES-
INCLUDING THE CITY OF...WHITNEY PORTAL
413 PM PDT MON OCT 4 2010

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 10 PM THIS
EVENING TO 11 AM PDT TUESDAY ABOVE 8500 FEET...

A WINTER WEATHER ADVISORY FOR ELEVATIONS ABOVE 8500 FEET REMAINS
IN EFFECT FROM 10 PM THIS EVENING TO 11 AM PDT TUESDAY FOR THE
EASTERN SLOPES OF THE SOUTHERN SIERRA.

* TIMING: SNOW WILL OCCUR ON THE PEAKS OF THE SIERRA TODAY THEN
SIGNIFICANT SNOW ACCUMULATIONS WILL BEGIN AT ELEVATIONS DOWN
TO 8500 FEET LATE THIS EVENING THROUGH TUESDAY MORNING.

* SNOW LEVEL: SNOW LEVELS WILL BE OBSERVED ABOVE 10000 FEET
TODAY AND WILL LOWER TO AROUND 7500 FEET TONIGHT...BUT
SIGNIFICANT ACCUMULATIONS CAN BE EXPECTED MAINLY ABOVE 8500
FEET.

* TOTAL SNOW ACCUMULATIONS: TOTAL SNOWFALL OF 4 TO 7 INCHES IS
EXPECTED BY LATE TUESDAY MORNING ABOVE 8500 FEET.

* WINDS: PREVAILING WINDS WILL BE EAST AT 10 TO 20 MPH WITH
HIGHER GUSTS OVER THE CREST.

* IMPACTS: SNOW ACCUMULATION WILL IMPACT ROADS AND CAMPGROUNDS
ABOVE 8500 FEET IN THE EAST SLOPES OF THE SOUTHERN SIERRA
INCLUDING THE COMMUNITY OF ASPENDELL.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER WEATHER ADVISORY FOR SNOW MEANS THAT PERIODS OF SNOW
WILL CAUSE PRIMARILY TRAVEL DIFFICULTIES. BE PREPARED FOR SNOW
COVERED ROADS AND LIMITED VISIBILITIES...AND USE CAUTION WHILE
DRIVING.

&&

$$
Member Since: November 8, 2009 Posts: 4 Comments: 13461
Quoting Neapolitan:
In late May, NOAA predicted an "extremely active" season ranging from a low of 14-8-3 to a high of 23-14-7. In August they revised downward to between 14-8-4 and 20-12-6.

Meanwhile, Klotzbach & Gray at CSU originally called for between 11-6-3 to 16-8-5; that was revised in June to 18-10-5.

In mid-June, the UK Met Office called for 20 storms, with a 70% chance of between 13 and 27, and a 70% chance of an ACE index between 90 to (a ludicrously high) 319.

So: we're at, obviously, 14-7-5, with an ACE of 131. That means we've reached the low end of the NOAA forecast for named storms, we're just one hurricane away from reaching their low end prediction for hurricanes, and we've almost doubled the minimum number of intense hurricanes they called for. It also means we've reached the low end of the CSU forecasts for named storms and hurricanes, and we've reached their predicted number of major storms. And, finally, it also means we've exceeded the low end of the UK Met prediction for both storms and ACE.

Ther bottom line: we're here at the start of October having already fallen in line with at least the low end of most of the pre-season predictions, despite the late start to anything more than minimal activity. There are nearly two months left in the regular season, there are still very-high SSTs across most of the MDR, and there are currently two AOIs, one looking healthier and healthier.

And yet I keep reading over and over here how the pre-season forecasts were wrong. How so? I never saw anyone reputable claim 2010 would be the Mother Of All Seasons (that title will likely long belong to 2005); I merely saw predictions of a very active to hyperactive season. Well, we're already at very active, and there's plenty of time left to reach hyperactive. Doing a post-mortem at this point seems about eight weeks premature...


Would pouring sugar into the gulf stream make for a hyperactive season? I think so...
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578. JLPR2
Quoting Gearsts:
12z EURO link please...


The one in the bottom

Link
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Quoting Dakster:
Pottery - About the only thing I can say that is true about this blog 100% of the time is that there isn't a consensus....

Two wunderbloggers, three opinions.


On average, three out of two people have trouble with fractions.
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12z EURO link please...
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Cape Verde season may be over... but African waves are still on the way.... What about that new wave spinnin
at 8N, 30W?? Seems like we will have to take her in consideration...

Member Since: Posts: Comments:
573. JLPR2
I hadn't seen this, 12z EURO O_O
48hrs


24hrs Possible 1006mb TD in the East coast of PR


Jeez, the EURO is amazing, it developed the low that didn't even exist then.
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562.Is on this page saying is moving wsw.
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In late May, NOAA predicted an "extremely active" season ranging from a low of 14-8-3 to a high of 23-14-7. In August they revised downward to between 14-8-4 and 20-12-6.

Meanwhile, Klotzbach & Gray at CSU originally called for between 11-6-3 to 16-8-5; that was revised in June to 18-10-5.

In mid-June, the UK Met Office called for 20 storms, with a 70% chance of between 13 and 27, and a 70% chance of an ACE index between 90 to (a ludicrously high) 319.

So: we're at, obviously, 14-7-5, with an ACE of 131. That means we've reached the low end of the NOAA forecast for named storms, we're just one hurricane away from reaching their low end prediction for hurricanes, and we've almost doubled the minimum number of intense hurricanes they called for. It also means we've reached the low end of the CSU forecasts for named storms and hurricanes, and we've reached their predicted number of major storms. And, finally, it also means we've exceeded the low end of the UK Met prediction for both storms and ACE.

Ther bottom line: we're here at the start of October having already fallen in line with at least the low end of most of the pre-season predictions, despite the late start to anything more than minimal activity. There are nearly two months left in the regular season, there are still very-high SSTs across most of the MDR, and there are currently two AOIs, one looking healthier and healthier.

And yet I keep reading over and over here how the pre-season forecasts were wrong. How so? I never saw anyone reputable claim 2010 would be the Mother Of All Seasons (that title will likely long belong to 2005); I merely saw predictions of a very active to hyperactive season. Well, we're already at very active, and there's plenty of time left to reach hyperactive. Doing a post-mortem at this point seems about eight weeks premature...
Member Since: November 8, 2009 Posts: 4 Comments: 13461

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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.