EPAC: POLO - Post-Tropical

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Re: EPAC: POLO - Tropical Storm

#121 Postby cycloneye » Sun Sep 21, 2014 5:37 am

TROPICAL STORM POLO DISCUSSION NUMBER 21
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172014
200 AM PDT SUN SEP 21 2014

Polo has continued to be impacted by strong easterly wind shear of
around 25 kt, which has severely weakened the associated convection.
What little convection that does exist has been displaced into the
western quadrant. A 0413 ASCAT-B overpass indicated several 33-kt
wind vectors in the northeastern and southwestern quadrants. Since
some undersampling is possible, the initial intensity is being
maintained at 35 kt for this advisory, especially since some
convective redevelopment could return during the remainder of the
convective maximum period this morning while the cyclone is over
SSTs near 28C.

Now that Polo's low and upper-level circulations are beginning to
weaken and decouple, the cyclone has made a westward jog and the
initial motion is now 285/06 kt. However, the track forecast and
reasoning basically remain unchanged from the previous advisory.
Polo is expected to continue to weaken and become more vertically
shallow, being steered westward and eventually southwestward by a
strengthening low- to mid-level ridge located to the north of the
cyclone. The NHC forecast track is similar to the previous advisory
track and TVCE multi-model consensus.

Strong easterly vertical wind shear is forecast to continue for the
next 36 hours or so, which should cause Polo to continue to weaken.
The cyclone will likely become a tropical depression later today,
and degenerate into a remnant low on Monday, if not sooner.
Although the remnant circulation will be moving back over warm
water on Days 3 and 4, the surrounding airmass is expected to be
dry and more stable, which should inhibit any persistent convective
development from occurring.

Given that the size of Polo's wind field has decreased and that the
cyclone is also now moving away from Baja California Sur, the
Government of Mexico has discontinued the tropical storm watch for
Baja California Sur.

FORECAST POSITIONS AND MAX WINDS

INIT 21/0900Z 21.6N 110.5W 35 KT 40 MPH
12H 21/1800Z 21.9N 111.7W 30 KT 35 MPH
24H 22/0600Z 22.1N 113.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 22/1800Z 22.0N 114.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 23/0600Z 21.5N 115.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 24/0600Z 20.3N 116.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 25/0600Z 19.0N 117.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 26/0600Z...DISSIPATED

$$
Forecaster Stewart
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Re: EPAC: POLO - Tropical Storm

#122 Postby cycloneye » Sun Sep 21, 2014 9:44 am

TROPICAL STORM POLO DISCUSSION NUMBER 22
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172014
800 AM PDT SUN SEP 21 2014

Polo is not in good shape. Strong easterly shear continues to
affect the cyclone, keeping the low-level center exposed to the east
of the nearest deep convection. The system has been producing
somewhat regular bursts of deep convection over the past couple of
days, with the latest burst currently on the increase. The initial
intensity is being held at 35 kt for this advisory in agreement with
the 1200 UTC TAFB Dvorak intensity estimate. With no cessation of
the strong shear seen in the short term, further weakening seems
likely to occur. However, Polo will be moving over warm enough water
to sustain additional bursts of convection, and thermodynamic
variables will only gradually become less conducive. The NHC
intensity forecast, like the previous one, shows slow weakening but
maintains the system as a tropical cyclone longer. The new forecast
is just above the latest intensity guidance and shows dissipation in
about 3 days in line with global model output.

Polo is moving slowly west-northwestward or 290/06 kt. A continued
west-northwestward and then westward track is expected during the
next day or so as a result of a westward building mid-level ridge
over northern Mexico. Once Polo becomes shallower in nature, a bend
of the track toward the southwest and south-southwest is indicated
as the cyclone is pushed by a north-northeasterly flow on the
eastern side of a low-level ridge. The new track forecast does not
depart significantly from the previous one but is shifted slightly
to the right in the direction of the well-performing multi-model
consensus, TVCE.


FORECAST POSITIONS AND MAX WINDS

INIT 21/1500Z 21.9N 111.2W 35 KT 40 MPH
12H 22/0000Z 22.2N 112.4W 30 KT 35 MPH
24H 22/1200Z 22.2N 113.8W 30 KT 35 MPH
36H 23/0000Z 21.9N 114.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 23/1200Z 21.4N 115.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 24/1200Z 20.1N 116.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 25/1200Z...DISSIPATED

$$
Forecaster Kimberlain
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Re: EPAC: POLO - Tropical Storm

#123 Postby cycloneye » Sun Sep 21, 2014 3:33 pm

BULLETIN
TROPICAL STORM POLO ADVISORY NUMBER 23
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172014
200 PM PDT SUN SEP 21 2014

...POLO MAINTAINING TROPICAL STORM STRENGTH FOR NOW...


SUMMARY OF 200 PM PDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...22.3N 112.1W
ABOUT 145 MI...235 KM WSW OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...WNW OR 290 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES


TROPICAL STORM POLO DISCUSSION NUMBER 23
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172014
200 PM PDT SUN SEP 21 2014

After an impressive burst of deep convection, strong easterly shear
has pushed the thunderstorm activity well west of the low-level
center. An ASCAT overpass from a few hours ago indicated that the
maximum winds were still near 35 kt. Since the shear is not
expected to abate much over the next day or two, and the
thermodynamic environment is expected to gradually become less
favorable, weakening is likely. The official intensity forecast is
similar to the previous one and is a blend of the latest
Decay-SHIPS and LGEM guidance. Polo should degenerate into a
remnant low within a couple of days.

Based on some microwave imagery and the scatterometer data, the
center is located slightly north of the previous track. The
initial motion estimate remains west-northwestward, or 290/7 kt. A
mid-level ridge to the north of Polo is expected to cause the
cyclone to turn westward within the next day or so. Thereafter, the
weakening remnant low should turn west-southwestward and then
southwestward within the shallow-layer northeasterly flow. The
official forecast is close to a consensus of the GFS and ECMWF
predictions.

FORECAST POSITIONS AND MAX WINDS

INIT 21/2100Z 22.3N 112.1W 35 KT 40 MPH
12H 22/0600Z 22.5N 113.1W 30 KT 35 MPH
24H 22/1800Z 22.5N 114.4W 30 KT 35 MPH
36H 23/0600Z 22.1N 115.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 23/1800Z 21.7N 116.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 24/1800Z 20.6N 117.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 25/1800Z...DISSIPATED

$$
Forecaster Pasch
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Re: EPAC: POLO - Tropical Storm

#124 Postby cycloneye » Sun Sep 21, 2014 9:33 pm

BULLETIN
TROPICAL STORM POLO ADVISORY NUMBER 24
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172014
800 PM PDT SUN SEP 21 2014

...POLO EXPECTED TO BECOME A REMNANT LOW ON MONDAY...


SUMMARY OF 800 PM PDT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...22.9N 113.2W
ABOUT 210 MI...340 KM W OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...WNW OR 290 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES



TROPICAL STORM POLO DISCUSSION NUMBER 24
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172014
800 PM PDT SUN SEP 21 2014

Only a very small area of convection remains, and it is associated
with Polo's remnant mid-level circulation about 120 n mi
west-northwest of the exposed low-level center. Despite the
current structure, the maximum winds probably have not decreased
significantly since the earlier ASCAT data, so the initial
intensity is held at 35 kt for now. Although the cyclone could
still produce some bursts of convection since it will remain over
26C water, persistent shear is likely to cause the winds to
continue to decrease gradually during the next few days. Polo will
likely become a post-tropical remnant low within the next 24 hours
if deep convection doesn't redevelop soon. Dissipation is expected
by late Thursday.

Polo appears to have sped up a bit, possibly due to the low-level
center being tugged westward by the earlier burst of deep
convection, and the initial motion is 290/9 kt. As the cyclone
weakens, it will become increasingly steered by low-level northerly
flow off the coast of the Baja California peninsula. This will
force Polo to turn westward and slow down on Monday and then turn
southwestward by late Tuesday. The updated NHC track forecast is
similar to the previous one and is close to the multi-model
consensus TVCE.

FORECAST POSITIONS AND MAX WINDS

INIT 22/0300Z 22.9N 113.2W 35 KT 40 MPH
12H 22/1200Z 23.0N 114.3W 30 KT 35 MPH
24H 23/0000Z 22.8N 115.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 23/1200Z 22.4N 116.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 24/0000Z 21.9N 116.8W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 25/0000Z 20.3N 117.5W 15 KT 15 MPH...POST-TROP/REMNT LOW
96H 26/0000Z...DISSIPATED

$$
Forecaster Berg
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Re: EPAC: POLO - Tropical Depression

#125 Postby cycloneye » Mon Sep 22, 2014 5:11 am

TROPICAL DEPRESSION POLO DISCUSSION NUMBER 25
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172014
200 AM PDT MON SEP 22 2014

Polo has been devoid of significant deep convection for about 10
hours now. Satellite images show that the cyclone consists of a
tight swirl of low-level clouds with a few deeper clouds located
over 100 n mi west of the center near the mid-level remnants.
The initial wind speed is lowered to 30 kt, following the latest
Dvorak classifications, making Polo a tropical depression.
Continued weakening is expected while the cyclone remains in an
environment of strong shear, dry air, and over relatively cool
waters. If deep convection does not return soon, Polo will likely
be declared a remnant low later today. The remnant low is forecast
to dissipate in 3 to 4 days.

The depression has moved west-southwestward during the past few
hours, but a longer term motion is 270/7. A slower westward motion
is expected today, followed by a turn to the southwest on Tuesday
while the shallow system is steered by a low-level ridge to its
northwest. The NHC track forecast is south of the previous one,
mainly to account for the initial position, and is near the
multi-model consensus TVCE.

FORECAST POSITIONS AND MAX WINDS

INIT 22/0900Z 22.5N 113.8W 30 KT 35 MPH
12H 22/1800Z 22.4N 114.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 23/0600Z 22.2N 115.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
36H 23/1800Z 21.8N 116.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 24/0600Z 21.2N 117.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 25/0600Z 20.0N 118.3W 15 KT 15 MPH...POST-TROP/REMNT LOW
96H 26/0600Z...DISSIPATED

$$
Forecaster Cangialosi
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Re: EPAC: POLO - Post-Tropical

#126 Postby cycloneye » Mon Sep 22, 2014 9:47 am

Last advisory.

BULLETIN
POST-TROPICAL CYCLONE POLO ADVISORY NUMBER 26
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172014
800 AM PDT MON SEP 22 2014

...POLO BECOMES A REMNANT LOW...
...THIS IS THE LAST ADVISORY...


SUMMARY OF 800 AM PDT...1500 UTC...INFORMATION
----------------------------------------------
LOCATION...22.2N 114.4W
ABOUT 290 MI...470 KM W OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...30 MPH...45 KM/H
PRESENT MOVEMENT...WSW OR 250 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES


POST-TROPICAL CYCLONE POLO DISCUSSION NUMBER 26
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172014
800 AM PDT MON SEP 22 2014

Polo has been absent of any organized deep convection for more than
12 hours. Although a few sporadic showers have developed since 0900
UTC over the western half of the circulation, strong east-
southeasterly shear and unfavorable thermodynamic factors should
inhibit any significant return of deep convection. Based on the
lack of deep convection for some time, the cyclone is being declared
a post-tropical remnant low on this advisory. The initial wind
speed estimate presumes some spin-down of the vortex since late
yesterday and is lowered to 25 kt on this advisory. Global models
shows Polo degenerating into an open trough by 48 hours, and so does
the official forecast.

Polo has been moving west-southwestward or 250/07. The now-shallow
vortex is expected to turn southwestward or south-southwestward
on the eastern periphery of a low-level ridge over the subtropical
eastern Pacific prior to dissipation. The track forecast is left
of much of the guidance, including the multi-model consensus, given
the already greater southerly component of motion.

For additional information on the remnant low of Polo please see
High Seas Forecasts issued by the National Weather Service...under
AWIPS header NFDHSFEPI and WMO header FZPN01 KWBC.

FORECAST POSITIONS AND MAX WINDS

INIT 22/1500Z 22.2N 114.4W 25 KT 30 MPH
12H 23/0000Z 22.0N 115.1W 20 KT 25 MPH...POST-TROP/REMNT LOW
24H 23/1200Z 21.7N 116.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
36H 24/0000Z 21.2N 116.6W 15 KT 15 MPH...POST-TROP/REMNT LOW
48H 24/1200Z...DISSIPATED

$$
Forecaster Kimberlain
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