Tropical Weather Discussion

axpz20 knhc 160405

Tropical weather discussion
NWS National Hurricane Center Miami FL
307 UTC Tue Oct 16 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 0000 UTC surface analysis and satellite imagery through
0245 UTC.

...Special features...

The center of Tropical Storm Tara is located near 18.4n 104.6w 
at 16/0300 UTC or 60 nm S of Manzanillo Mexico drifting NW or 
325 degrees at 2 kt. Estimated minimum central pressure is 1000 
mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. 
Numerous moderate and scattered strong convection is noted 
within 60 nm in the NW and within 30 nm in the se semicircle. 
Scattered moderate and isolated strong convection is seen
elsewhere from 17.5n to 20n between 103.5w and 106w. The future 
track of Tara is highly uncertain. Tara is forecast to move 
slowly toward the northwest and then west at a similar speed 
during the next couple of days. The center of Tara should pass 
very close to the coast of southwestern Mexico, or possibly move 
inland, on Tuesday and Wednesday. See latest NHC 
forecast/advisory under AWIPS/WMO headers miatcpep2/wtpz32 knhc 
for more details.

Gulf of california: a Gale Warning remains in effect for the 
northern Gulf of California until around midnight. A recent ascat
pass provided observations of near gale force sustained winds 
across the northern Gulf of California. These winds are the 
result of robust high pressure building over the Great Basin of 
the United States. Fresh to strong winds are expected to persist 
across much of the Gulf through early Wed. 

...Intertropical convergence zone/monsoon trough... 

The monsoon trough extends from 16n84w to a 1006 mb low pressure
centered over the SW Caribbean near 15n85w, then across Central 
America to near the Gulf of tehunatepec at 17n96w to 09n122w to 
11n129w to beyond 08n140w. Numerous moderate and scattered strong
convection is found within 60 nm either side of a line from
08n82w to 13n85w to 19n99w. Scattered moderate and isolated 
strong convection is seen elsewhere from 10n to 17n between 90w
and 98w. Scattered moderate and isolated 
strong convection is occurring within 120 nm either side of a
line from 13n99w to 11n119w and from 07n to 11n between 128w and


Offshore waters within 250 nm of Mexico... 

Latest scatterometer data indicate moderate to locally fresh NW
winds N of Punta eugenia, and gentle to moderate NW to N winds
elsewhere across the offshore forecast waters W of Baja
California. A ridge will continue to dominate the offshore 
waters W of Baja California peninsula producing mainly gentle to 
moderate NW to N winds, and seas generally in the 4 to 6 ft 
range, with the exception of moderate to fresh winds N of Punta 
eugenia tonight through Tue night. Seas are forecast to increase 
a foot or so by the end of the forecast period as mixed swell 
generated by Tropical Storm Tara arrives. 

Gulf of tehuantepec: next gap wind event is forecast to start 
early on Wed with seas rapidly building to 10 ft by Wed 
afternoon. This event will be associated with a ridge building
behind a cold front across the eastern slopes of Sierra Madre 
Mountains in Mexico and the western Gulf of Mexico.

Offshore waters within 250 nm of Central America, Colombia, and 
within 750 nm of Ecuador...

Moderate to fresh SW monsoonal flow will continue across the 
region through Tue, with showers and thunderstorms expected to 
continue along the Pacific coast of Central America. Long period 
cross-equatorial SW swell will maintain 5 to 8 ft seas across the
forecast area during this time frame. By Tue night and Wed, 
marine guidance suggests an increase in winds and seas across the
offshore waters from northern Costa Rica to Guatemala. This 
appears to be associated with an area of low pressure forecast 
to develop a couple of hundred miles south of Guatemala and the 
southeastern coast of Mexico around mid-week. 

Remainder of the area...

A 1021 mb high pressure located near 30n127w extends a ridge 
across the northern forecast waters. The pressure gradient 
between the ridge and a cold front approaching from the W is
resulting in fresh to strong southerly winds across the far NW 
waters, mainly NW of a line from 30n138w to 26n140w. Moderate to
locally fresh trades are noted S of 15n and N of the monsoon
trough W of 125w. The cold front is forecast to reach a position
from 0n138w to 27n140w on Tue, and from 30n138w to 27n138w to 
25n140w on Wed, when it is forecast to become stationary. Long 
period NW swell will follow the front building seas of 8-10 ft.

Satellite-derived wind and altimeter data confirmed the presence
of moderate to fresh monsoonal flow across much of the forecast
waters. Winds increase near the convection. An area of 7 to 9 ft
in long period SW swell is noted south of the monsoon trough and
mainly between 100w and 120w.

Looking ahead, an area of low pressure is forecast to develop a 
couple of hundred miles south of Guatemala and the southeastern 
coast of Mexico around mid-week. Environmental conditions are 
forecast to be conducive for development, and a tropical 
depression is likely to form by late week while the system moves 
west-northwestward near the southern coast of Mexico. The latest 
tropical weather outlook gives this system a high change of 
tropical cyclone formation through 5 days.



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