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Eastern North Pacific Tropical Weather Discussion



368 
AXPZ20 KNHC 260916
TWDEP 

Tropical Weather Discussion 
NWS National Hurricane Center Miami FL
1005 UTC Wed Sep 26 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 0600 UTC surface analysis and satellite imagery through 
0915 UTC.

...SPECIAL FEATURE... 

Tropical Storm Rosa is centered near 15.1N 109.7W at 26/0300 UTC 
or 390 nm SW of Manzanillo Mexico moving WNW at 8 kt. Estimated 
minimum central pressure is 997 mb. Maximum sustained wind speed 
is 55 kt with gusts to 65 kt. Currently numerous moderate to 
strong convection is observed in bands within 90 nm southeast 
and 270 nm northwest semicircles of center. Rosa is forecast to 
soon intensify to hurricane strength with continued gradual 
strengthening thereafter for the next few days. Associated winds 
and seas are forecast to spread across the offshore waters of 
Mexico W of 105W during the next few days, and recurve northeast 
across the offshore waters west of Baja California early next 
week. See latest NHC forecast/advisory under AWIPS/WMO headers 
MIATCPEP5/WTPZ35 KNHC for more details.

...TROPICAL WAVES...

A tropical wave formally along 104W has lost identity. 

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

The monsoon trough extends W off the Pacific coast of Colombia 
at 08N78W to 09N94W then turns northwest to 12N100W where it 
loses identity. The monsoon trough resumes west of Rosa at 
13N115W and continues southwest to near an embedded surface low 
at 10.5N140W. Scattered moderate isolated strong convection is 
observed across the Gulf of Panama...within 150 nm of a line 
from 10.5N86W to 13N94W, within 90 nm of a line from 06.5N87W to 
06.5N91W, within 75 nm of a line from 14.5N97.5W to 20N107W, 
within 30 nm of a line from 15.5N118W to 13.5N125W and within 
120 nm of a line from 10N117W to 09N130W.  

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

See the Special Features paragraph above for information on 
Tropical cyclone Rosa. A west to east ridge along 21N will 
gradually retract west of the area ahead of Tropical Cyclone 
Rosa. Gentle to moderate northwest flow is forecast west of the 
Baja California through Fri, then becoming northerly early this 
upcoming weekend, with marine conditions deteroiating late in 
the upcoming weekend.   

Gulf of California: Light to gentle mostly southerly winds 
expected across the gulf waters through Sun night with the flow 
ind=creasing thereafter. 

Gulf of Tehuantepec: Fresh to locally strong northerly flow 
forecast through late Thu morning. A strong drainage event is 
expected on Fri night into early Sat as a tropical low passes to 
the southwest.

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

Gulf of Papagayo: Moderate to locally fresh east nocturnal 
drainage flow expected across and downstream of the Gulf of 
Papagayo through the upcoming weekend.  

Gentle east winds are forecast through this morning elsewhere 
north of the monsoon trough which is meandering between 09N and 
12N. Moderate southwest flow is forecast south of the monsoon 
trough. The pressure gradient will begin to tighten tonight as a 
surface low develops near 10N94W. The low and associated 
conditions will shift west of the area on Thu night. 

REMAINDER OF THE AREA...   

See the Special Features paragraph above for information on 
Tropical Cyclone Rosa.  A broad ridge continues across the 
subtropics accompanied by moderate to locally fresh anticyclonic 
flow south of 23N west of 120W. A series of weak cold fronts, or 
troughs, will sweep east across the far NW waters through the 
upcoming weekend accompanied by a moderate west to northwest 
wind shift.

$$
Nelson