ATL: INVEST 97L - Discussion

[cycloneye]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT SAT SEP 17 2011

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

A BROAD LOW PRESSURE SYSTEM LOCATED ABOUT 400 MILES SOUTHEAST OF THE
SOUTHERN CAPE VERDE ISLANDS IS PRODUCING DISORGANIZED SHOWERS AND
THUNDERSTORMS. SOME SLOW DEVELOPMENT OF THIS LOW IS POSSIBLE DURING
THE NEXT COUPLE OF DAYS AS IT MOVES WESTWARD AT 10 TO 15 MPH. THIS
SYSTEM HAS A MEDIUM CHANCE...30 PERCENT ...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER CANGIALOSI

[cycloneye]

Discussion by Rob of Crown Weather:

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org. For Official Information please refer to the NHC and NWS products.

http://www.crownweather.com/?page_id=4557

Invest 97L In The Far Eastern Atlantic:
I wanted to write briefly on a area of low pressure that is located way out in the eastern Atlantic, about 325 miles to the south-southeast of the Cape Verde Islands. This low pressure system has been designated Invest 97L by the National Hurricane Center. Satellite imagery indicates that this disturbance has become better organized overnight and development into a tropical depression is certainly possible over the next few days as it tracks westward.

The track guidance is pointing towards a general westward track to near 14 North Latitude, 42 or 43 West Longitude by about Wednesday. The SHIPS intensity guidance points to some development into a tropical storm by Monday or Tuesday, but then forecasts weakening as shear values increase by Tuesday and Wednesday.

This is something to keep an eye on, however, I highly doubt this will be a threat anytime soon, if ever. The GFS model does seem to hint at this system possibly affecting Barbados, the Windward Islands and Trinidad and Tobago right around Friday as a tropical storm & enter the far southeastern Caribbean next Saturday before quickly lifting northward across Puerto Rico and then out into the open Atlantic late next weekend.

[wxman57]

Very little rotation visible on TPW loop:
http://cimss.ssec.wisc.edu/tropic/real- ... /main.html

Satellite presence not impressive. I'd say development chances next 48 hrs are near zero. Beyond 48 hrs, in the 3-5 day time frame, maybe 40-50%, which is close to average for any tropical wave in September. Slower development, which I think is very likely, would almost certainly mean a greater risk of an East Caribbean impact down the road (late next week).

[cycloneye]

12z Best Track

They repositioned the latitude and longitude towards the larger cluster of convection to the east.

AL, 97, 2011091712, , BEST, 0, 103N, 200W, 20, 1009, LO

ftp://ftp.tpc.ncep.noaa.gov/atcf/tcweb/ ... 011.invest

[Extratropical94]

First dvorak estimate, hasn't been posted yet:

17/1145 UTC 10.3N 19.3W T1.0/1.0 97L -- Atlantic

[Adoquín]

the get into the Eastern carribbean and then striking either PR or DR in a south to north direction has been shown in several of the later gfs outcomes. Something to watch but stil plenty of other outcomes possible like an earlier turn north. It is prime for hurricanes forming in mid September to strike the NE Caribbean.

[Gustywind]

From NRL:
http://www.nrlmry.navy.mil/tc-bin/tc_ho ... m&PROD=vis


20110917.1530.97LINVEST.20kts-1009mb-103N-200W.

[cycloneye]

OSCAT made around 9:10 AM EDT shows a broad low pressure in the area.



Uploaded by ImageShack.us

[Florida1118]

Looks good to develop...



Wind shear is deadly to the north though. Looks like 50-60+ knots...

[jinftl]

Climatologically, it is prime time for the ne caribbean...but the actual weather pattern right looks way to hostile for this to even develop much...several models drop it completely, i.e., dissipate it, long before it would ever be anything than maybe be a mechanism for increased afternoon convection...if it ever gets as far west as the islands before being too far north.

Look at Lee, a system in the bathtub waters of the Gulf in late August....the same waters that bred Katrina almost 6 years to the day earlier than Lee.....same area of prime climatologic development, very different result when so many other factors were proving too hostile for Lee.

Looking at past tracks of systems that developed within 150 miles of where 97L is now (10N 20W)...in other words, the far eastern atlantic in September, only 2 made it as far as the Islands as tropical depressions (and one dissipated just north of hispanola, the other recurved and dissipated southeast of Bermuda).... The color code for the map below: blue is a tropical depression, green is tropical storm, yellow is a Cat 1, orange is Cat 2, red is Cat 3.




If this system could get to 45W or 50W at 15N or south latitude, then the likelihood of direct impacts on the islands increases significantly. Most models call for 97L to dissipate by the time it reaches that location due to hostile conditions.

the get into the Eastern carribbean and then striking either PR or DR in a south to north direction has been shown in several of the later gfs outcomes. Something to watch but stil plenty of other outcomes possible like an earlier turn north. It is prime for hurricanes forming in mid September to strike the NE Caribbean.

[cycloneye]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT SAT SEP 17 2011

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

AN ELONGATED AREA OF LOW PRESSURE EXTENDING A FEW HUNDRED MILES
SOUTH AND SOUTHWEST OF THE CAPE VERDE ISLANDS IS PRODUCING
DISORGANIZED SHOWERS AND THUNDERSTORMS. SOME SLOW DEVELOPMENT OF
THIS SYSTEM IS POSSIBLE DURING THE NEXT COUPLE OF DAYS AS IT MOVES
WESTWARD AT 10 TO 15 MPH. THIS SYSTEM HAS A LOW CHANCE...20
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER CANGIALOSI

Look how large is the circle.

[cycloneye]

18z Best Track

AL, 97, 2011091718, , BEST, 0, 104N, 205W, 20, 1009, LO

[cycloneye]

I smell a merge of low pressures as now TAFB at 18z surface analysis has added another low.



Uploaded by ImageShack.us

[underthwx]

Dr. Masters:

Invest 97L
For the first day since August 18, we don't have a named storm in the Atlantic. However, we have a new area to watch. A tropical wave that moved off the coast of Africa Friday and is now 300 miles south of the Cape Verde Islands is moving west at 10 - 15 mph. The wave has developed a modest amount of heavy thunderstorm activity and spin, and has been designated Invest 97L by NHC. Wind shear as diagnosed by the SHIPS model is light, 5 - 10 knots, and is predicted to stay light to moderate through Tuesday morning. Ocean temperatures are 27.5°C, one degree above the threshold typically needed for a tropical storm to spin up. Water vapor satellite images show 97L is embedded in a moist environment.


Personal Forecast Disclaimer:
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[jinftl]

Probably the key to predicting what may happen by mid week is the following from the Dr. Masters excerpt below:

Wind shear as diagnosed by the SHIPS model is light, 5 - 10 knots, and is predicted to stay light to moderate through Tuesday morning.

In other words, after Tuesday, conditions will become less conducive for development - as shear results in a more hostile environment.


Dr. Masters also stated in the same blog today:

"It is likely 97L will encounter the usual troubles storms this year have had with wind shear and dry air on the long trek across the Atlantic."
http://www.wunderground.com/blog/JeffMa ... rynum=1932

Dr. Masters:

Invest 97L
For the first day since August 18, we don't have a named storm in the Atlantic. However, we have a new area to watch. A tropical wave that moved off the coast of Africa Friday and is now 300 miles south of the Cape Verde Islands is moving west at 10 - 15 mph. The wave has developed a modest amount of heavy thunderstorm activity and spin, and has been designated Invest 97L by NHC. Wind shear as diagnosed by the SHIPS model is light, 5 - 10 knots, and is predicted to stay light to moderate through Tuesday morning. Ocean temperatures are 27.5°C, one degree above the threshold typically needed for a tropical storm to spin up. Water vapor satellite images show 97L is embedded in a moist environment.


Personal Forecast Disclaimer:
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[Adoquín]

Dr. Masters:

Invest 97L
For the first day since August 18, we don't have a named storm in the Atlantic. However, we have a new area to watch. A tropical wave that moved off the coast of Africa Friday and is now 300 miles south of the Cape Verde Islands is moving west at 10 - 15 mph. The wave has developed a modest amount of heavy thunderstorm activity and spin, and has been designated Invest 97L by NHC. Wind shear as diagnosed by the SHIPS model is light, 5 - 10 knots, and is predicted to stay light to moderate through Tuesday morning. Ocean temperatures are 27.5°C, one degree above the threshold typically needed for a tropical storm to spin up. Water vapor satellite images show 97L is embedded in a moist environment. .

that would seem to suggest westbound and low through Tuesday morning as shear seems higher further north.

[wxman57]

Still looks like near zero percent chance of development within 48 hours. Have to wait a while for development. Maybe next Tue-Wed.

[cycloneye]

AN ELONGATED AREA OF LOW PRESSURE LOCATED A FEW HUNDRED MILES SOUTH
AND OF THE CAPE VERDE ISLANDS IS PRODUCING LIMITED SHOWER ACTIVITY.
HOWEVER...SOME SLOW DEVELOPMENT OF THIS SYSTEM IS POSSIBLE DURING
THE NEXT COUPLE OF DAYS AS IT MOVES WESTWARD AT 10 TO 15 MPH. THIS
SYSTEM HAS A LOW CHANCE...20 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

[cycloneye]

AN ELONGATED AREA OF LOW PRESSURE IS LOCATED ABOUT 300 MILES SOUTH
OF THE CAPE VERDE ISLANDS. THIS SYSTEM HAS CHANGED LITTLE AND
DEVELOPMENT...IF ANY...SHOULD BE SLOW TO OCCUR AS IT INTERACTS WITH
A LARGER DISTURBANCE TO ITS SOUTHWEST. THIS SYSTEM HAS A LOW
CHANCE...10 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS AS MOVES WEST-NORTHWESTWARD AT 10 TO 15 MPH.

[cycloneye]

We can say bye to this one.

AN ELONGATED AREA OF LOW PRESSURE LOCATED ABOUT 300 MILES SOUTH OF
THE CAPE VERDE ISLANDS IS PRODUCING ONLY LIMITED SHOWER AND
THUNDERSTORM ACTIVITY. THIS SYSTEM HAS BECOME LESS ORGANIZED OVER
THE PAST FEW HOURS...AND TROPICAL CYCLONE DEVELOPMENT APPEARS
UNLIKELY. THIS SYSTEM HAS A LOW CHANCE...NEAR 0 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES
WESTWARD AT 10 TO 15 MPH.