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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 260251

TROPICAL WEATHER DISCUSSION                                  
0405 UTC THU MAY 26 2016

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
0215 UTC.


A tropical wave axis is analyzed over the far eastern part of the area
along 79W north of 05N...moving west near 10 kt. The wave is just 
to the southeast of a rather strong upper trough that extends from
the western Caribbean sea to just south of the Costa Rica/Panamanian
border. Clusters of scattered strong convection are seen over much of Panama.
Scattered moderate to strong convection is over central and southern Costa Rica. 


The monsoon trough axis extends from 10N85W TO 08N95W TO 09N103W
to low pres near 09N109W 1012 mb TO 11N116W TO 12N123W. ITCZ axis
extends from 08N125W TO 06N140W. Scattered moderate to isolated
strong convection is within 240 NM s of the trough between 109W-115W...
within 180 nm north of the trough between 110W-115W and within 
120 nm s of the trough between 115w-117w. Scattered moderate 
convection is s of the trough within 60 nm of a line from 06N82W TO


Strong high pressure centered well to the north of the area near 42N137W
extends a ridge southeastward to 32N132W to 24N118W to south of Baja
California Sur near 19N109W. High pressure covers the area north of 15N west
of 109W. The pressure gradient between the ridge and lower pressure across
Baja California is producing moderate to fresh northwest winds west of the
Baja California Peninsula to near 118W. The ridge is supporting moderate to
locally fresh trade winds N of the convergence zone and S of 22N W of 120W.
A weak 1011 mb low is embedded along the monsoon trough near 09N109W as 
indicated in last visible imagery. The 1630Z Ascat pass from Wednesday showed
cyclonic turning of wind vectors within about 240 nm of the low. The low is
located to the southeast of a broad upper anticyclone centered near 14N118W.
Moderate to strong easterly upper winds over the southern semicircle of the
anticyclone are shearing off the cold tops of the deep convection associated
near the low as well as that along and near the monsoon trough segment with
the low. Global model guidance track the low in a general west-northwest
direction over the next 48 hours while remaining on the weak side. A weak
surface trough is analyzed from 12N134W to 07N135W...moving west at 10 to 15 kt.
The 1810Z Ascat pass from Wednesday depicted wind direction from east to southeast
e of the trough axis to northeast west of the axis. In addition...visible 
satellite imagery shows pretty clear evidence of cyclonic turning of the low-level
clouds within about 210 nm either side of the trough. Seas across the tropical
zone are forecast to remain in the 5-7 ft range through Friday.

Over the far eastern portion of the area...southwest moderate to fresh southwest
winds are forecast by the Global models to increase to the strong category early
on Friday as another low pressure center forms along the monsoon trough near 10N86W.
Current seas of 5-7 ft found there will gradually build to 6-8 ft by Friday afternoon 
as the strong southwest winds increase in duration. The strong southwest winds are
forecast to diminish to 15-20 kt by Friday evening.

Gulf of California...
Strong high pressures ridging nosing southeastward along the west coast of Baja
California is interacting with the thermal trough along the east coast of Baja
California peninsula. The resultant tight gradient is bringing moderate to 
strong southwest to west across the far northern part of the Gulf. These winds
are forecast to increase to near gale force in a short bit before diminishing 
back to strong late tonight...and decrease further to 15-20 kt towards 12Z 
Thursday. A brief instance of strong northwest winds is expected along
the far northern boundary of the Gulf tonight.