AXPZ20 KNHC 250229

0405 UTC WED MAY 25 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 was analyzed to the n of 06N along 78.5W, and has been moving w at 15-20 kt. Currently scattered moderate isolated strong convection is noted from 04-10N to the e of 87W including over and along the coasts of Colombia and Panama.


The monsoon trough was analyzed from 10N85W to 08N93W to 11N116W to an embedded 1012 mb surface low pres at 10N124W with the monsoon trough continuing sw to 07N137W where scatterometer winds indicate an ITCZ forms and continues sw to beyond 07N140W.

Scattered moderate isolated strong convection is observed within 120 nm of lines from 08N94W to 07N99W,and from 06N105W to 12N115W. Similar convection is noted within 180 nm of line from 10N119W to 06N140W.

The surface low is forecast to move nw to near 12N125W on Thu and then dissipate on Thu night. The gradient is supporting fresh to strong ne winds over the w semicircle of the low.


N of 15N e of 120W:

A NNW-SSE surface trough is currently analyzed over the Gulf of California. The trough will meander e and w over the next few days. Moderate southwesterly winds are expected to develop briefly early tonight across the gulf waters from 29.5-31N and e of the trough. Strong to near conditions will develop again on Wed afternoon from 29-31N, while NW-N 20-25 kt condtions are expected n of 31N and will persist into late Wed night.

A surface ridge extends from 24N120W to 19N107W. The ridge is expected to shift slightly sw on Wed. Moderate NW-N winds currently across the open Pacific are expected to increase to a fresh breeze tonight across the waters n of 28N within 120 nm of the Baja Peninsula. The winds will briefly diminish to 20 kt or less early Wed, then develop again late Wed. The gradient will continue to tighten on Thu with strong to near gale winds from 28-32N e of 118W late Thu. The gradient should begin to relax on Fri.

Strong nw to n winds are forecast from 19-24N e of 111W late Wed, and will spread w across the waters from 18-21N between 105- 108W late Thu.

Combined seas of 3-6 ft are currently observed between 110-120W. Little change expected until the winds increase n of the ridge with seas then expected to build to near 8 ft in the area of strong winds. Combined seas of 4-7 ft are expected across the remainder of the open Pacific waters n of 15N e of 110w, partially due to long-period cross equatorial swell.

S of 15N e of 110W:

Moderate ne drainage flow expected across the Gulf of Papagayo tonight, then mostly light drainage flow is expected the rest of the week. Light drainage flow is expected this week across the Gulf of Panama.

Otherwise, gentle northerly flow expected n of the monsoon trough with combined seas of 4-7 ft in mixing cross-equatorial southerly swell and long-period nw swell. Light to moderate southerly flow currently across the waters s of the monsoon trough is expected to increase to a fresh breeze on Thu with seas building from 4-7 ft to 5-8 ft.

Elsewhere from the equator to 32N e of 140W:

A surface ridge extends from 32N140W to beyond 24N120W. Moderate to fresh anticyclonic flow is expected n of the ridge till Thu night when the gradient will support strong nw-n winds along 32N. These conditions will spread s to along 30N between 122- 130W on Fri night accompanied by 8-11 ft seas.

Fresh to locally strong ne trades expected across the tropics n of the monsoon trough and ITCZ this week with combined seas of 5- 8 ft.

$$ Nelson