Tropical Cyclone Discussion
Issued by NWS
WTPZ41 KNHC 291449
TROPICAL STORM ANDRES DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012015
900 AM MDT FRI MAY 29 2015
Andres is just below hurricane strength. Although an eye feature
is no longer apparent in infrared and visible satellite images, the
associated convection has been deepening during the past few hours.
Microwave images show that the structure of Andres is asymmetric
with well-defined banding to the south of the center and limited
more fragmented bands to the north of the center. A blend of the
latest Dvorak estimates and ADT values still yield an intensity
estimate of 60 kt.
The SHIPS model indicates that Andres is currently experiencing
about 15 kt of northerly shear, which is likely part of the reason
why the storm has leveled off in intensity for the time being. This
shear is expected to persist for another 12 to 24 hours, but it
should lessen some thereafter. Therefore, slow strengthening is
expected during the next couple of days while the cyclone remains
over warm water. Beyond a couple of days, Andres is expected to
move over cooler water and into a drier and more stable airmass.
These unfavorable thermodynamic conditions should cause the system
to weaken. The official intensity forecast is a little lower than
the previous one, and lies at the high end of the model guidance.
Andres continues on a west-northwestward track at about 8 kt. A
weakness in the subtropical ridge should cause the storm to move
northwestward during the next day or two. After that time, a turn
back to the west-northwest is predicted when the ridge restrengthens
to the north of the storm. The model guidance is in good agreement
overall, and the official forecast is similar to the previous one
and lies close to the consensus aids.
FORECAST POSITIONS AND MAX WINDS
INIT 29/1500Z 12.5N 114.6W 60 KT 70 MPH
12H 30/0000Z 13.3N 115.5W 65 KT 75 MPH
24H 30/1200Z 14.3N 116.4W 70 KT 80 MPH
36H 31/0000Z 15.4N 117.4W 75 KT 85 MPH
48H 31/1200Z 16.2N 118.5W 80 KT 90 MPH
72H 01/1200Z 17.3N 121.3W 65 KT 75 MPH
96H 02/1200Z 18.2N 124.3W 50 KT 60 MPH
120H 03/1200Z 18.8N 127.4W 40 KT 45 MPH