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Eastern North Pacific Tropical Weather Discussion



249 
AXPZ20 KNHC 252124
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2124 UTC Tue Sep 25 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 1800 UTC surface analysis and satellite imagery through
2030 UTC.

...SPECIAL FEATURE... 

Tropical Storm Rosa centered near 15.0N 108.9W at 25/2100 UTC or
360 nm SW of Manzanillo Mexico moving WNW at 8 kt. Estimated
minimum central pressure is 1000 mb. Maximum sustained wind
speed is 45 kt with gusts to 55 kt. Numerous moderate to strong
convection is within 240 nm in the SW quadrant. Scattered 
moderate to strong convection is within 210 nm in the N 
semicircle and 90 nm in the SE quadrant. Rosa is forecast to 
rapidly intensify to hurricane strength late tonight with 
continued strengthening thereafter for the next few days. 
Associated winds and seas are forecast to spread into the 
offshore waters of Mexico W of 100W the next few days, continuing
to spread NW offshore of SW Mexico and will reach the waters of 
Baja California through the end of the week into the upcoming 
weekend. Large swells associated with Rosa are likely to impact 
these areas as well as the entrance to the Gulf of California by 
the end of the week. See latest NHC forecast/advisory under 
AWIPS/WMO headers MIATCPEP5/WTPZ35 KNHC for more details.

...TROPICAL WAVES...

A tropical wave is analyzed from 05N to 17N along 102W moving
westward around 10 kt. Scattered moderate and isolated strong
convection is from 08N to 14.5N between 99W and 104W.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

The monsoon trough axis extends from northern Colombia near
09N74W to 09N90W to 13N101W, then resumes from 12N114W to 
11N126W to low pressure near 10N138W. Scattered moderate and
isolated strong convection is from 03N to 06N between 77W and 
85W, and also within an area bounded by 15N100W to 15N97W to
09N83W to 05N90W to 04N94W to 08N100W to 15N100W. Scattered
moderate convection is from 08N to 11N between 124W and 129W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

Please see the special features section for information on
Tropical Storm Rosa.

A ridge extending from 28N120W to 21N113W will continue to 
gradually retract NW as Rosa moves NW. Gentle to moderate NW
flow is forecast W of the Baja California through Fri with light
to gentle variable winds in the Gulf of California. Much
uncertainty exists thereafter due to Rosa.

In the Gulf of Tehuantepec, fresh to strong northerly flow 
is forecast through the next several days, except briefly 
diminishing during the mid afternoons. The strongest drainage 
event is expected on Thu night into early Fri as a tropical low 
passes to the S.

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

In the Gulf of Papagayo, fresh to locally strong E nocturnal 
drainage flow is expected starting Wed night with a surface low 
developing near 09.5N90.5W Wed afternoon, moving to near 11N95W 
Thu afternoon.

Elsewhere, light and variable winds are forecast through Wed 
morning elsewhere N of the monsoon trough which will meander 
between 09N and 12N. Moderate SW flow is forecast S of the 
monsoon trough. The pressure gradient will begin to tighten on 
Wed night as the surface low develops.

REMAINDER OF THE AREA...   

Please see the special features section for information on
Tropical Storm Rosa.

Otherwise, a broad ridge continues across the subtropics 
accompanied by moderate to locally fresh anticyclonic flow S of 
23N W of 120W. A weak cold front or trough may drop into the far
NW portion by the end of the week into the upcoming weekend.

$$
Lewitsky