ATL: KARL - Post-Tropical - Discussion

[GCANE]

Pretty decent rain rate and cold cloud tops

[abajan]

Raised to 40%/60% for 8pm. Still has it at 50% for five days for some reason.
http://www.nhc.noaa.gov/xgtwo/two_atl_5d2.png

They were probably in the process of updating the info. Incidentally, that image currently shows the outlook for another system which is yet to emerge from Africa. The image will continue to change with time because it was linked directly.

[GCANE]

AMSU Microwave Sounder estimated a 1C warm core about 6.5 hrs ago

[Kazmit]

Raised to 40%/60% for 8pm. Still has it at 50% for five days for some reason.
http://www.nhc.noaa.gov/xgtwo/two_atl_5d2.png

They were probably in the process of updating the info. Incidentally, that image shows the outlook for another system which is yet to emerge from Africa.

Weird. I think I fixed it now.

[GCANE]

[GCANE]

GFS is forecasting the worst shear in about 42 hrs from 400mb up. After that, it looks like it will gradually let up.
350K PV seems to clear out a bit at is approaches the Leewards.

[abajan]

Raised to 40%/60% for 8pm. Still has it at 50% for five days for some reason.
http://www.nhc.noaa.gov/xgtwo/two_atl_5d2.png

They were probably in the process of updating the info. Incidentally, that image shows the outlook for another system which is yet to emerge from Africa.

Weird. I think I fixed it now.

Actually, it's still going to be a problem because that URL, like the other one, is dynamic and the image changes with time, according to which system is in the number 1 slot. That's one of the reasons for this rule.

[AutoPenalti]

Looks like the ridge begins to erode rather quickly on that run. That could change though, ridge never erodes and 95L keeps treking to the west.

[cycloneye]

Up to 70%-70%

A low pressure system, associated with a tropical wave, is moving
through the Cabo Verde Islands. Satellite imagery indicates that
shower and thunderstorm activity associated with this low has
become better organized overnight. If current trends continue,
advisories on a tropical depression would be initiated later today.
Locally heavy rains and gusty winds are likely over portions of the
Cabo Verde Islands today.
* Formation chance through 48 hours...high...70 percent
* Formation chance through 5 days...high...70 percent

[abajan]

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 AM EDT WED SEP 14 2016

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through
1015 UTC.

...TROPICAL WAVES...

An Atlantic Ocean tropical wave is along 23W/24W from 21N
southward. A 1009 mb low pressure center is along the wave near
16N. Convective precipitation: scattered to numerous strong from
15N to 18N between 23W and 25W, in parts of the Cabo Verde
Islands.

-----------------------------------------------------------------------------

From the image in the 5-day TWO, it seems they expect its forward motion to decelerate. The cone also seems to indicate a possibility of a more westerly movement.

[SFLcane]

id venture to say this recurves into the open Atlantic or doesn't develop.

[Gustywind]

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 AM EDT WED SEP 14 2016

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through
1015 UTC.

...TROPICAL WAVES...

An Atlantic Ocean tropical wave is along 23W/24W from 21N
southward. A 1009 mb low pressure center is along the wave near
16N. Convective precipitation: scattered to numerous strong from
15N to 18N between 23W and 25W, in parts of the Cabo Verde
Islands.

-----------------------------------------------------------------------------

From the image in the 5-day TWO, it seems they expect its forward motion to decelerate. The cone also seems to indicate a possibility of a more westerly movement.

Absolutely and curiously NHC TWD do not mention any direction but looks like imo a more westerly track during the next couple of days. We will see.

[abajan]

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 AM EDT WED SEP 14 2016

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through
1015 UTC.

...TROPICAL WAVES...

An Atlantic Ocean tropical wave is along 23W/24W from 21N
southward. A 1009 mb low pressure center is along the wave near
16N. Convective precipitation: scattered to numerous strong from
15N to 18N between 23W and 25W, in parts of the Cabo Verde
Islands.

-----------------------------------------------------------------------------

From the image in the 5-day TWO, it seems they expect its forward motion to decelerate. The cone also seems to indicate a possibility of a more westerly movement.

Absolutely and curiously NHC TWD do not mention any direction but looks like imo a more westerly track during the next couple of days. We will see.

It certainly seems to be well on its way to becoming a TD, judging from this Meteosat IR satellite image:

[Gustywind]

Yeah man even why not a small TS given my untrained eyes.

[SeGaBob]

Nothing to be concerned about anywhere. (except Cape Verde) Just a gut feeling...

[HurricaneBelle]

If they name this while it's over Cabo Verde, we could have two storms in two days named over land.

[ConvergenceZone]

Yep, almost can say fishy for sure on this one, but that's normal for developing waves this far out

[wxman57]

12Z models initialized as TD Twelve. Clearly a TD. The only land impacts will be the Cape Verde islands. Fish after that.

[bg1]

...NEW TROPICAL DEPRESSION FORMS OVER THE WESTERN CABO VERDE ISLANDS...

[cycloneye]

BULLETIN
TROPICAL DEPRESSION TWELVE ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016
1100 AM AST WED SEP 14 2016

...NEW TROPICAL DEPRESSION FORMS OVER THE WESTERN CABO VERDE
ISLANDS...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...17.0N 25.0W
ABOUT 95 MI...155 KM NW OF THE CABO VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...1009 MB...29.80 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
At 1100 AM AST (1500 UTC), the center of Tropical Depression Twelve
was located near latitude 17.0 North, longitude 25.0 West. The
depression is moving toward the west-northwest near 14 mph (22 km/h)
and a gradual turn toward the west is expected during the next
couple of days. On the forecast track, the center of the depression
should move through the western islands of Cabo Verde this
afternoon and move away from the islands tonight.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Slight strengthening is expected during the next 24 hours, and the
depression could become a tropical storm tonight. After that time,
some weakening could occur as the cyclone encounters unfavorable
upper-level winds.

The estimated minimum central pressure is 1009 mb (29.80 inches).


HAZARDS AFFECTING LAND
----------------------
WIND: Gusty winds are possible over portions of the Cabo Verde
Islands through tonight.

RAINFALL: Locally heavy rains are expected over portions of the Cabo
Verde Islands through Thursday.


NEXT ADVISORY
-------------
Next complete advisory at 500 PM AST.

$$
Forecaster Beven



TROPICAL DEPRESSION TWELVE DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016
1100 AM AST WED SEP 14 2016

Satellite imagery, scatterometer data, and surface observations
indicate that the low pressure area over the Cabo Verde Islands has
developed a well-defined circulation and sufficient organized
convection to be considered a tropical depression. The initial
intensity is set at 30 kt based on the scatterometer data along
with satellite intensity estimates from TAFB and SAB.

The initial motion is 300/12. A low- to mid-level ridge should
steer the system west-northwestward and then westward during the
forecast period, with some decrease in forward speed after 36 hours
as the ridge weakens slightly. The forecast track is near the
center of the guidance envelope and close to the various consensus
models.

Some strengthening is expected during the next 12-24 hours. After
that, the cyclone is likely to encounter strong westerly vertical
wind shear while over sea surface temperatures of about 26C. This
combination should lead to weakening, and the intensity forecast
shows the system weakening back to a depression by 36 hours. Near
the end of the forecast period, the dynamical models diverge on the
evolution of the upper-level winds, with the ECMWF and UKMET
forecasting a more favorable pattern than the GFS. Based on this,
the forecast shows some re-intensification by 120 hours. An
alternative scenario is that the cyclone degenerates to a tropical
wave as forecast by the GFS. Overall, the intensity forecast is on
the low side of the guidance in best agreement with the LGEM.

Locally heavy rains and gusty winds are possible over the Cabo
Verde Islands. However, current indications are that the cyclone
will not reach tropical-storm strength until it has moved west of
the islands. Therefore, watches and warnings are not required at
this time.


FORECAST POSITIONS AND MAX WINDS

INIT 14/1500Z 17.0N 25.0W 30 KT 35 MPH
12H 15/0000Z 17.5N 26.8W 35 KT 40 MPH
24H 15/1200Z 17.9N 29.3W 35 KT 40 MPH
36H 16/0000Z 17.9N 31.7W 30 KT 35 MPH
48H 16/1200Z 17.8N 34.0W 30 KT 35 MPH
72H 17/1200Z 17.5N 38.0W 30 KT 35 MPH
96H 18/1200Z 17.5N 41.5W 35 KT 40 MPH
120H 19/1200Z 18.0N 45.5W 40 KT 45 MPH

$$
Forecaster Beven