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HURRICANE ANDRES DISCUSSION NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012015
800 PM PDT FRI MAY 29 2015
Andres is gradually intensifying. The cyclone is maintaining a
symmetric central dense overcast, consisting of plenty of
cold-topped deep convection. A 2256 UTC GPM microwave pass showed
numerous, well organized convective bands and a closed low-level
ring of convection; in addition, a warm spot has recently become
evident in infrared satellite imagery. Satellite intensity
estimates at 0000 UTC were 4.0/65 kt and 4.5/75 kt from SAB and
TAFB, respectively, and the latest ADT value from UW-CIMSS is 4.3/72
kt. Since that time, Andres' cloud pattern has increased further in
organization, and the initial intensity is raised to 75 kt.
Andres' motion has shifted toward the right or northwest, 320/06, in
response to a weakness in the subtropical ridge along 115w caused
by a shortwave trough near the Baja California peninsula. After
this feature moves eastward tomorrow, the ridge is forecast to
rebuild which should result in the track's bending toward the west-
northwest and west by 36 to 48 hours. For this forecast cycle,
there has been a notable shift in the guidance to the left through
48 hours, and the track has generally been shifted in that direction
but not as far left as the ECMWF and GFS solutions. After 48 hours,
the spread in the guidance increases, with the GFS depicting a
stronger cyclone on the northern end of the guidance envelope and
the ECMWF a weaker one on the southern edge. The official NHC
forecast track lies nearly between the two extremes, close to the
multi-model consensus (TVCE).
The intensity forecast is challenging. Despite moderate northerly
shear, the cyclone has slowly strengthened during the past 24
hours. Although this shear is forecast to persist through
tomorrow, the cyclone's inner-core structure suggests that further
intensification should occur. The official forecast exceeds the
statistical-dynamical guidance through 36 hours on the basis of
current trends and the hurricane's well organized inner core.
Although the shear should lessen in a day or two, weakening should
commence as thermodynamics in the near-storm environment gradually
become less conducive for intensification. The official NHC
intensity forecast shows steady weakening after 36 hours, very
similar to the multi-model consensus (ICON).
FORECAST POSITIONS AND MAX WINDS
INIT 30/0300Z 13.4N 115.2W 75 KT 85 MPH
12H 30/1200Z 14.2N 116.0W 85 KT 100 MPH
24H 31/0000Z 15.1N 117.1W 85 KT 100 MPH
36H 31/1200Z 15.7N 118.4W 80 KT 90 MPH
48H 01/0000Z 16.2N 119.6W 75 KT 85 MPH
72H 02/0000Z 17.4N 122.3W 60 KT 70 MPH
96H 03/0000Z 18.6N 125.7W 50 KT 60 MPH
120H 04/0000Z 19.1N 128.8W 35 KT 40 MPH
$$
Forecaster Kimberlain
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