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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 181602
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 UTC Fri Aug 18 2017

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 1200 UTC surface analysis and satellite imagery through 
1545 UTC.

...SPECIAL FEATURE...

Hurricane Warning...Tropical Depression 13-E has formed at 14.8N 
116.5W, or about 705 miles SW of the southern tip of the Baja 
California Peninsula. Central pressure is estimated at 1006 mb. 
Maximum sustained winds are 30 kt with gusts to 40 kt. Scattered 
strong convection is currently observed in bands within 180 nm 
over the N, and within 240 nm over the S semicircles of the 
center. The system is expected to strengthen to a tropical storm 
within 12 hours, and then gradually strengthen to a minimal 
hurricane in 48 hours. Refer to National Hurricane Center 
Forecast Advisory under WMO/AWIPS headers WTPZ23 KNHC/MIATCMEP3, 
and the High Seas Forecast under WMO/AWIPS headers FZPN03 
KNHC/MIAHSFEP2 for additional information.

..TROPICAL WAVES AND TROPICAL LOWS...

A tropical wave is analyzed to the N of 05N between 95W AND 97W.
This wave has been progressing W at about 18 kts over the past 
24 hours, but is expected to slow it's forward speed somewhat 
over the next few days. Scattered moderate isolated strong 
convection is observed within 150 nm E, and within 240 nm W of 
the wave axis.

A tropical wave is analyzed from 13N112W to 23N109W, and has 
moved W at 15 kt over the past 24 hours. Scattered moderate and 
isolated strong convection is observed to the N of 20N within 
60 nm either side of the wave axis.

A 1009 mb surface low is analyzed N of the monsoon trough at 
17N128W. Fresh NE to E winds are observed within 390 nm over 
the NW semicircle of the low with seas of 6 to 7 ft. Isolated 
strong convection has been flaring intermittently within 180 nm 
over the S semicircle. The low is forecast to move w and weaken 
into to open trough tonight.  

The remnants of former tropical cyclone Jova continue to spin 
near 18N140W with a pressure of about 1010 mb. Scattered moderate
convection is currently noted within 120 nm over the NE quadrant
of the low. The pressure gradient is supporting moderate to
locally fresh N to NE winds and 6 to 7 ft seas within 420 nm 
over the NE quadrant of the low. The low is forecast to move 
W of 140W today. 

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

The monsoon trough extends W across the far SW Caribbean from 
09N76W to across the northern Gulf of Panama to the Pacific 
Coast of Costa Rica at 09N84W, then turns slightly W-SW to 
07N103W, then NW to 08N108W where it loses identity.  The 
monsoon trough resumes SW of the newly formed TD 13-E and 
extends SW to 10N125W, then W to 11N134W, then NW to beyond 
13N140W.

Except as previously mentioned, scattered moderate isolated 
strong convection is noted off the Pacific Coast of Colombia 
from 02N to 08N to the of 82W.  Similar convection is noted 
along the monsoon trough within 75 nm either side of a line from 
09N83W to 07N98W to 10N102W, within 75 nm of 08.5N110W, and 
within 180 nm either side of a line from 07N117W to 11N124W to 
09N140W.    
...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A NW to SE orientated low level trough will meander E to W 
across the Baja California Peninsula and Gulf of California 
through Mon night with a surface low developing intermittently 
along the trough over the far northern Gulf of California 
waters. A NW to SE orientated ridge extends across the offshore 
waters W of the southern tip of Baja. A moderate NW breeze is 
forecast through the weekend to the W of the Baja California 
Peninsula, except the pressure gradient will tighten each 
evening with fresh NW flow within 90 nm of the Baja coast with 3 
to 6 ft seas.

Gulf of California...light to gentle southerly flow will persist 
across the Gulf of California through the upcoming weekend, 
except a moderate to locally fresh breeze will surround the low 
pressure center over the waters N of 29.5N.

Gulf of Tehuantepec: fresh to locally brief and strong N 
drainage winds are forecast during the overnight hours with seas 
building to 8 ft downstream of the Gulf waters near 15N95W.   

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

Gulf of Papagayo: moderate nocturnal drainage forecast through 
the weekend.

Otherwise, light and variable to gentle NE to E flow expected N 
of the monsoon trough throughearly Mon, while moderate to 
locally fresh southerly winds are expected S of the monsoon 
trough axis with 3 to 6 ft seas throughout.

REMAINDER OF THE AREA...

The subtropical ridge extends from 32N136W to near 23N116W. 
Except as previously mentioned in the above paragraphs, moderate 
to locally fresh anticyclonic flow is forecast N of the monsoon 
trough and W of 120W. 

$$
Nelson