Surface Trough in Western Atlantic

[USTropics]

A lot of convergence over this system:

[Ptarmigan]

A lot of convergence over this system:

Could that one develop next and become Tropical Depression #8 or even Humberto?

[USTropics]

A lot of convergence over this system:

Could that one develop next and become Tropical Depression #8 or even Humberto?

That's a hard question to answer. There is very limited scientific data on storms this close in proximity and how they behave in the Atlantic. Generally, one is absorbed by the other (and usually, if a larger system is present, that system ends up absorbing the smaller one).

The last time I can recall this happening in the Atlantic basin was in 2005. TS Lee rotated around an ULL. It strengthened when on the NE side of the ULL, before weakening as it moved northwestward around the eastern side and eventually absorbed the low. Same year, Alpha ended up being absorbed by Hurricane Wilma. It will be interesting to document what happens in this scenario.

[galaxy401]

Can this be just like Unala from the CPAC? It formed very close to Pewa.

[northjaxpro]

Deep convection really flaring up over this tropical wave at this hour. I am really curious just how this system will interact with Gabrielle in the short term. Thers is a lot of energy with the tropical wave that is certainly evident.

[Gustywind]

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU SEP 05 2013


TROPICAL WAVE APPROACHING THE LESSER ANTILLES EXTENDS FROM
21N62W TO 12N60W. WAVE HAS BEEN MOVING W NEAR 10 KT FOR THE PAST
24 HOURS. WAVE IS EMBEDDED WITHIN A BROAD AREA OF DEEP MOISTURE
AS DEPICTED ON TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED
MODERATE TO STRONG CONVECTION IS FROM 17N-22N BETWEEN 57W-63W
WITH CLUSTERS OF SIMILAR CONVECTION FROM 14N-17N BETWEEN 57W-
64W. THE UPPER RIDGE OVER TROPICAL STORM GABRIELLE IS ENHANCING
THE ACTIVITY ASSOCIATED WITH THIS WAVE.

[Gustywind]

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU SEP 05 2013

TROPICAL WAVE ENTERING THE E CARIBBEAN EXTENDS FROM 18N62W TO
11N62W. WAVE HAS BEEN MOVING W NEAR 10 KT FOR THE PAST 24 HOURS.
THE N PORTION OF THE WAVE HAS SPLIT AND IS NOW DEPICTED AS A
SURFACE TROUGH NE OF THE LEEWARD ISLANDS. WAVE IS EMBEDDED
WITHIN A BROAD AREA OF DEEP MOISTURE AS DEPICTED ON TOTAL
PRECIPITABLE WATER IMAGERY. SEE SPECIAL FEATURES ABOVE FOR
ACTIVITY IN THE VICINITY.

[Gustywind]

Title should be edited as chances have increased now 20%-20%.

[galaxy401]

This thing is up to 20% now.

A LARGE AREA OF DISORGANIZED SHOWERS AND THUNDERSTORMS...ASSOCIATED
WITH A SURFACE TROUGH...EXTENDS FROM THE NORTHEAST LEEWARD ISLANDS
NORTHEASTWARD OVER THE ATLANTIC WATERS FOR SEVERAL HUNDRED MILES.
ANY DEVELOPMENT OF THIS SYSTEM IS EXPECTED TO BE SLOW DUE TO ITS
PROXIMITY TO TROPICAL STORM GABRIELLE AND STRONG UPPER-LEVEL WINDS.
THIS SYSTEM HAS A LOW CHANCE...20 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES NORTHWESTWARD AT 10 TO
15 MPH. DEVELOPMENT IS NOT EXPECTED AFTER 48 HOURS...AND THIS
SYSTEM HAS A LOW CHANCE...20 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 5 DAYS.

[Gustywind]

8 AM Tropical Weather Outlook.

A LARGE AREA OF DISORGANIZED SHOWERS AND THUNDERSTORMS...ASSOCIATED
WITH A SURFACE TROUGH...EXTENDS FROM THE NORTHEAST LEEWARD ISLANDS
NORTHEASTWARD OVER THE ATLANTIC WATERS FOR SEVERAL HUNDRED MILES.
ANY DEVELOPMENT OF THIS SYSTEM IS EXPECTED TO BE SLOW DUE TO ITS
PROXIMITY TO TROPICAL STORM GABRIELLE AND STRONG UPPER-LEVEL WINDS.
THIS SYSTEM HAS A LOW CHANCE...20 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES NORTHWESTWARD AT 10 TO
15 MPH. DEVELOPMENT IS NOT EXPECTED AFTER 48 HOURS...AND THIS
SYSTEM HAS A LOW CHANCE...20 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 5 DAYS.

[CrazyC83]

This looks to BE Gabrielle now? The winds are higher in that and it is eating Gabby's moisture and circulation...

[Extratropical94]

A LARGE AREA OF DISORGANIZED SHOWERS AND THUNDERSTORMS...ASSOCIATED
WITH A SURFACE TROUGH...EXTENDS FROM THE NORTHERN LEEWARD ISLANDS
NEAR TROPICAL DEPRESSION GABRIELLE NORTHWARD OVER THE ATLANTIC
WATERS FOR SEVERAL HUNDRED MILES. ANY DEVELOPMENT OF THIS SYSTEM IS
EXPECTED TO BE SLOW DUE TO STRONG UPPER-LEVEL WINDS. THIS SYSTEM
HAS A LOW CHANCE...20 PERCENT...OF BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS AS IT MOVES NORTHWESTWARD AT 10 TO 15 MPH.
SOME DEVELOPMENT COULD ALSO OCCUR IN A FEW DAYS WHEN THE SYSTEM
MOVES NORTHEASTWARD AHEAD OF A COLD FRONT OVER THE CENTRAL ATLANTIC
OCEAN. THIS SYSTEM HAS A MEDIUM CHANCE...30 PERCENT...OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 5 DAYS.

[Gustywind]

2 PM TWD.

AN ATLANTIC OCEAN TROPICAL WAVE IS ABOUT 260 NM TO THE EAST OF
T.D. GABRIELLE. THIS WAVE IS ALONG 62W/64W TO THE SOUTH OF 20N.
THE WAVE IS MOVING WESTWARD 10 TO 15 KNOTS. A SURFACE TROUGH IS
ALONG 26N59W 24N61W 21N63W. A MIDDLE LEVEL TO UPPER LEVEL
CYCLONIC CIRCULATION CENTER IS NEAR 29N60W. A TROUGH EXTENDS
FROM THE CYCLONIC CENTER TO 26N63W AND 23N68W. CONVECTIVE
PRECIPITATION...NUMEROUS STRONG FROM 19N TO 22N BETWEEN 61W AND
64W. NUMEROUS STRONG IS REACHING SOUTHERN COASTAL PUERTO RICO
AND THE VIRGIN ISLANDS. NUMEROUS STRONG ALSO COVERS THE EASTERN
CARIBBEAN SEA ISLANDS FROM GUADELOUPE TO DOMINICA TO MARTINIQUE.
CLUSTERS OF RAINSHOWERS COVER THE REST OF THE CARIBBEAN SEA
BETWEEN 60W AND 70W. THE 24-HOUR RAINFALL TOTAL IN INCHES FOR
THE PERIOD ENDING AT 05/1200 UTC...ACCORDING TO THE PAN AMERICAN
TEMPERATURE AND PRECIPITATION TABLES...MIATPTPAN...IS 0.17 IN
GUADELOUPE. SCATTERED MODERATE TO ISOLATED STRONG FROM 28N TO
30N BETWEEN 52W AND 57W. SCATTERED MODERATE FROM 23N TO 28N
BETWEEN 53W AND 60W. ANY DEVELOPMENT OF THIS SYSTEM IS
EXPECTED TO BE SLOW DUE TO STRONG UPPER-LEVEL WINDS. THIS SYSTEM
HAS A LOW CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT
48 HOURS AS IT MOVES NORTHWESTWARD AT 10 TO 15 MPH. IT IS POSSIBLE
THAT SOME DEVELOPMENT MAY OCCUR IN A FEW DAYS WHEN THE SYSTEM
MOVES NORTHEASTWARD AHEAD OF A COLD FRONT OVER THE CENTRAL ATLANTIC
OCEAN. THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 5 DAYS.

[cycloneye]

A LARGE AREA OF DISORGANIZED SHOWERS AND THUNDERSTORMS...ASSOCIATED
WITH A SURFACE TROUGH...EXTENDS FROM THE GREATER ANTILLES NEAR
TROPICAL DEPRESSION GABRIELLE NORTHWARD OVER THE ATLANTIC WATERS
FOR SEVERAL HUNDRED MILES. ANY DEVELOPMENT DURING THE NEXT COUPLE
OF DAYS IS EXPECTED TO BE SLOW DUE TO STRONG UPPER-LEVEL
WINDS...AND THIS SYSTEM HAS A LOW CHANCE...20 PERCENT...OF BECOMING
A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES
NORTHWESTWARD AT 10 TO 15 MPH. SOME DEVELOPMENT OF THIS SYSTEM
COULD ALSO OCCUR IN A FEW DAYS WHEN IT INTERACTS WITH TROPICAL
DEPRESSION GABRIELLE OR ITS REMNANTS AND MOVES NORTHEASTWARD AHEAD
OF A COLD FRONT OVER THE CENTRAL ATLANTIC OCEAN. THIS SYSTEM HAS A
MEDIUM CHANCE...30 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING
THE NEXT 5 DAYS.

[Gustywind]

8 PM Tropical Weather Discussion.

A SURFACE TROUGH IS NE OF GABRIELLE FROM 24N64W TO 20N68W.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS E OF THE
TROUGH AXIS FROM 16N-24N BETWEEN 60W-64W. ANY DEVELOPMENT OF
THIS TROUGH DURING THE NEXT COUPLE OF DAYS IS EXPECTED TO BE
SLOW DUE TO STRONG UPPER-LEVEL WINDS...AND THIS SYSTEM HAS A LOW
CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS
AS IT MOVES NORTHWESTWARD AT 10 TO 15 MPH. SOME DEVELOPMENT OF
THIS SYSTEM COULD ALSO OCCUR IN A FEW DAYS WHEN IT INTERACTS
WITH TROPICAL DEPRESSION GABRIELLE OR ITS REMNANTS AND MOVES
NORTHEASTWARD AHEAD OF A COLD FRONT OVER THE CENTRAL ATLANTIC
OCEAN. THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 5 DAYS.

[CrazyC83]

There is obscene shear in the area though! If it beats the odds and survives to 25-30N, then maybe...

[Extratropical94]

2. DISORGANIZED SHOWERS AND THUNDERSTORMS...ASSOCIATED WITH A SURFACE
TROUGH...EXTEND FROM PUERTO RICO NORTHEASTWARD ACROSS THE ADJACENT
ATLANTIC. SURFACE PRESSURES ARE CURRENTLY RISING AND DEVELOPMENT OF
THIS DISTURBACE...IF ANY...WILL BE SLOW TO OCCUR. THIS SYSTEM HAS A
LOW CHANCE...10 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS AS IT MOVES NORTHWESTWARD AT 10 TO 15 MPH. SOME
DEVELOPMENT OF THIS SYSTEM IS POSSIBLE IN A FEW DAYS WHEN THE
DISTURBANCE MOVES NORTHEASTWARD AHEAD OF A COLD FRONT AND INTERACTS
WITH REMNANTS OF GABRIELLE OVER THE CENTRAL ATLANTIC OCEAN. THIS
SYSTEM HAS A MEDIUM CHANCE...30 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 5 DAYS.

[cycloneye]

DISORGANIZED SHOWERS AND THUNDERSTORMS...ASSOCIATED WITH A SURFACE
TROUGH...EXTEND FROM PUERTO RICO NORTHEASTWARD ACROSS THE ADJACENT
ATLANTIC. SURFACE PRESSURES ARE CURRENTLY RISING AND DEVELOPMENT OF
THIS DISTURBACE...IF ANY...WILL BE SLOW TO OCCUR. THIS SYSTEM HAS A
LOW CHANCE...10 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS AS IT MOVES NORTHWESTWARD AT 10 TO 15 MPH. SOME
DEVELOPMENT OF THIS SYSTEM IS POSSIBLE IN A FEW DAYS WHEN THE
DISTURBANCE MOVES NORTHEASTWARD AHEAD OF A COLD FRONT AND INTERACTS
WITH REMNANTS OF GABRIELLE OVER THE CENTRAL ATLANTIC OCEAN. THIS
SYSTEM HAS A MEDIUM CHANCE...30 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 5 DAYS.

[CrazyC83]

Needs to get closer to the front or tuck in behind it. It won't do anything before it gets closer to 30N, where it can get some baroclinic forcing.

[cycloneye]

AN AREA OF DISTURBED WEATHER...ASSOCIATED WITH A TROUGH OF LOW
PRESSURE...HAS BECOME MORE CONCENTRATED ABOUT 500 MILES SOUTH OF
BERMUDA. DEVELOPMENT OF THIS SYSTEM DURING THE NEXT 48 HOURS...IF
ANY...IS EXPECTED TO BE SLOW TO OCCUR DUE TO UNFAVORABLE
UPPER-LEVEL WINDS. AFTER 48 HOURS...THE SYSTEM IS EXPECTED TO
MERGE WITH A FRONTAL SYSTEM AND NO DEVELOPMENT IS EXPECTED. THIS
SYSTEM HAS A LOW CHANCE...10 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS...AND A LOW CHANCE...10
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT FIVE DAYS.