344 
AXPZ20 KNHC 300322
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
117 UTC Sun Sep 30 2018

Tropical Weather Discussion for the eastern Pacific Ocean from
the Equator to 32N, east of 140W. The following information is
based on satellite imagery, weather observations, radar, and
meteorological analysis.

Based on 0000 UTC surface analysis and satellite imagery through
0300 UTC.
    
...SPECIAL FEATURES... 

A tropical storm warning has been issued along the west coast of
Baja California. Hurricane Rosa is centered near 22.4N 118.9W at
30/0300 UTC or about 380 nm (710 km) SSW of Punta Eugenia Mexico
moving N or 360 degrees at 10 kt. Estimated minimum central 
pressure is 969 mb. Maximum sustained wind speed is 85 kt with 
gusts to 105 kt. Numerous moderate to strong convection is noted 
within 120 nm of the center. On the forecast track, the center 
of Rosa will approach the central and northern Baja California 
peninsula on Monday. Rosa's remnants will then move quickly 
across the Desert Southwest of United States on Tuesday. Flooding
rains from Rosa are expected across NW Mexico and the SW of
United States between late Sunday and the middle of next week.
Swells generated by Rosa will affect portions of the coasts
of southwestern Mexico, most of the west coast of the Baja
California peninsula, and southern California during this weekend
and early next week. These swells are likely to cause life- 
threatening surf and rip current conditions. See latest NHC 
forecast/advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25 KNHC 
for more details.

Farther south, Tropical Storm Sergio is centered near 12.3N 
103.3W at 30/0300 UTC or 330 nm SSW of Acapulco Mexico moving W 
or 275 degrees 9 kt. Estimated minimum central pressure is 1003
mb. Maximum sustained wind speed is 40 kt with gusts to 50 kt. 
Convection is on increase near Sergio's center. Numerous 
moderate to strong convection is noted within 120 nm SE and 60 nm
NW semicircles of center. An earlier scatterometer satellite 
pass indicated the strongest winds were still displaced somewhat 
on the eastern side of the center. Strengthening is forecast during 
the next 72 hours, and Sergio could become a hurricane by Monday
and a major hurricane on Tuesday. See latest NHC forecast/advisory
under AWIPS/WMO headers MIATCMEP1/WTPZ21 KNHC for more details.

...TROPICAL WAVES...
A tropical wave is over SE Mexico, and extends along 90W north 
of 04N. Scattered moderate convection is where the wave meets the
monsoon trough. 
  
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

The monsoon trough extends from 08N83W to 10N93W to 11N98W, then
continues from 07N104W to 06N115W. Another sector of the monsoon
trough is SW of Hurricane Rosa, and extends from 13N125W to
08N135W. No significant convection.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

See Special Features above for information on Hurricane Rosa and 
Tropical Storm Sergio.

Swell associated with Rosa will continue to propagate across the
offshore forecast waters W of Baja California. Seas in the form 
of mixed swell in excess of 8 ft are observed over most of the 
ocean from 10N to 28N between 110W and 130W. Weather conditions 
will gradually deteriorate as Rosa approaches the area on Monday.

In the Gulf of California, gentle to moderate southerly winds 
are expected through Sun night. The southerly flow will increase 
to near gale force N of 27N thereafter, with tropical storm 
conditions possible N of 29N Mon night and Tue from Rosa. 

In the Gulf of Tehuantepec, fresh to strong northerly winds are
expected with seas building to 9 ft tonight through Mon night. 

OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND 
WITHIN 750 NM OF ECUADOR...

The monsoon trough will meander between 09N and 12N through mid
week, with gentle to moderate winds expected on either side of 
the trough axis. Moderate to fresh E nocturnal drainage flow is 
expected in the Gulf of Papagayo through Sun night.

REMAINDER OF THE AREA...   

See Special Features above for information on Hurricane Rosa and
Tropical Storm Sergio.

A weak ridge, anchored by a 1016 mb high centered near 25N142W, 
dominates the waters north of 20N and west of Rosa producing 
gentle to moderate winds N of 23N W of 120W, and moderate to 
fresh trades S of 23N. A weak cold front will reach the far NW
corner tonight followed by long period NW swell. This swell event
will propagate across the forecast waters through early next 
week, mixing with swell generated from Rosa, and later in the 
week from Sergio as it continues westward to the south of the 
Revillagigedo Islands.

$$
GR