Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 PM PDT Wed Sep 13 2017

For the eastern North Pacific…east of 140 degrees west longitude:

The National Hurricane Center is issuing advisories on Tropical
Depression Fifteen-E, located several hundred miles southwest
of the southern tip of the Baja California peninsula, and on
Tropical Storm Max, located near the southwest coast of Mexico.

1. A broad area of low pressure located several hundred miles south
of the southern tip of the Baja California peninsula is gradually
becoming organized, and a tropical depression is expected to form
within the next couple of days while the system moves slowly
northwestward. For more information on this system, please see High
Seas Forecasts issued by the National Weather Service.
* Formation chance through 48 hours…high…80 percent.
* Formation chance through 5 days…high…90 percent.

2. An area of low pressure located about 1500 miles east-southeast of
the Hawaiian Islands is producing persistent but disorganized shower
and thunderstorm activity. Satellite imagery indicates that a
well-defined center does not currently exist and additional
development, if any, is expected to be slow to occur while this
system moves little during the next several days.
* Formation chance through 48 hours…low…10 percent.
* Formation chance through 5 days…low…20 percent.

High Seas Forecasts issued by the National Weather Service can be
found under AWIPS header NFDHSFEPI, WMO header FZPN02 KWBC, and on
the web at http://www.opc.ncep.noaa.gov/shtml/NFDHSFEPI.shtml.

Public Advisories on Max are issued under WMO header WTPZ31 KNHC
and under AWIPS header MIATCPEP1.
Forecast/Advisories on Max are issued under WMO header WTPZ21 KNHC
and under AWIPS header MIATCMEP1.

Forecaster Avila

MAX EXPECTED TO MOVE INLAND WITHIN THE WARNING AREA LATER TODAY… …LIFE-THREATENING FLOODING EXPECTED ACROSS PORTIONS OF SOUTHWESTERN MEXICO

 Tropical Storm Max Discussion Number 4
NWS National Hurricane Center Miami FL EP162017
400 AM CDT Thu Sep 14 2017

We have good data this morning. Very useful radar images from
Mexico show that Max’s structure has improved during the past few
hours. An excellent ASCAT pass over the system was helpful in
determining the intensity and the tropical-storm-force wind radii.
Furthermore, the ship A8MW6 reported 45 kt winds and 11 foot waves
near the coast of Mexico. Based on these data, the initial intensity
was adjusted to 55 kt. At this point, it would only take a small
increase in intensity for Max to reach the coast as a hurricane.
Once the center moves inland the cyclone is forecast to weaken
quickly and dissipate within 36 hours.

Max is moving toward the east-northeast or 070 degrees at 5 kt. The
storm is embedded within a west-southwest flow and this flow
pattern will steer Max toward Mexico until dissipation. Based on
the forecast track, the core should be inland within the warning
area within the next 12 hours.

Max will produce life-threatening flooding rainfall in portions of
the states of Guerrero and Oaxaca.

FORECAST POSITIONS AND MAX WINDS

INIT 14/0900Z 16.6N 100.5W 55 KT 65 MPH
12H 14/1800Z 16.9N 99.7W 60 KT 70 MPH…INLAND
24H 15/0600Z 17.0N 99.0W 35 KT 40 MPH…INLAND
36H 15/1800Z…DISSIPATED

$$
Forecaster Avila

TROPICAL DEPRESSION REMAINS POORLY ORGANIZED

Tropical Depression Fifteen-E Discussion Number 11
NWS National Hurricane Center Miami FL EP152017
200 AM PDT Thu Sep 14 2017

The depression continues to be disorganized with the low- and
middle-level centers well separated due to shear. This can be
clearly observed on conventional imagery as well as microwave data.
Given the lack of organization, the initial intensity is kept at 30
kt, and no change in strength is anticipated during the next 24
hours or so. After that time, the shear is forecast to decrease, and
the depression could become better organized and reach tropical
storm status. This is the scenario provided by most of the guidance.

My best estimate of the initial motion is toward the west-northwest
or 285 degrees at 4 kt. The depression continues to be trapped
within weak steering flow, and only a small westward drift is
forecast. In fact, by the end of the forecast period, the steering
currents are expected to collapse, and the cyclone will probably
begin to meander. The NHC forecast follows most of the guidance up
to 4 days. After that time, models diverge considerably and the
forecast is highly uncertain.

FORECAST POSITIONS AND MAX WINDS

INIT 14/0900Z 15.3N 122.2W 30 KT 35 MPH
12H 14/1800Z 15.5N 123.0W 30 KT 35 MPH
24H 15/0600Z 15.5N 124.0W 30 KT 35 MPH
36H 15/1800Z 15.5N 124.8W 35 KT 40 MPH
48H 16/0600Z 15.5N 125.3W 40 KT 45 MPH
72H 17/0600Z 15.5N 125.5W 45 KT 50 MPH
96H 18/0600Z 15.5N 125.5W 50 KT 60 MPH
120H 19/0600Z 16.5N 125.5W 45 KT 50 MPH

$$
Forecaster Avila