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AXPZ20 KNHC 161616
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1605 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 1200 UTC surface analysis and satellite imagery through 1515 UTC.


...SPECIAL FEATURES...

The center of Tropical Storm Tara is located near 18.6N 104.5W at 1500 UTC, or ABOUT 26 nm SSW of Manzanillo Mexico, drifting NNW or 335 degrees at 1 kt. Estimated minimum central pressure is 1001 mb. Maximum sustained wind speed is 40 kt with gusts to 50 kt. Scattered to numerous moderate to strong convection is noted surrounding Tara from 17.5N TO 21.5N and within 75 nm of the Mexican coast, and extending inland up to 30 nm. Upper level southeast winds have sheared Tara significantly overnight, with convection recently making a come back. However the proximity to the coast and weakened state of the system will likely lead to gradual weakening during the next 24-48 hours as it moves slowly toward the northwest. Tara is now forecast to weaken t a 30 kt tropical depression within 24 hours, a 25 kt post-tropical low within 48 hours, and then dissipate by 72 hours. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCPEP2/WTPZ32 KNHC for more details.

Gulf of California: Strong NNW winds continue across the far northern Gulf of California and extends southward into central portions along 26N. High pressure over the Great Basin of the United States is forcing this wind flow. One last pulse of strong northerly winds are expected this evening before winds begin to subside by Wed morning as the high moves E and weakens.


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

The monsoon trough extends from 19N87W TO LOW PRES 1008 MB NEAR 16N88.5W TO 09.5N120W TO 10.5N136W to beyond 08N140W. Numerous moderate and scattered strong convection is found from 04N to 07N E of 80W. Scattered moderate isolated strong convection is seen N of a line from 07N82W to 11N92W and within 180 nm of the monsoon trough axis W of 95W.


...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

High pressure off the northern California coast extends SSE into the region and is maintaining moderate to locally fresh NW winds over the offshore forecast waters W of Baja California. The ridge currently extends from a 1022 mb high to near the Revillagigedo Islands and will maintain its influence over the offshore waters W of Baja California throughout the week, yielding seas of 4-6 ft. A new pulse of NW swell will arrive late Thu through Fri to raise seas to 5-7 ft.

Gulf of Tehuantepec: The next gap wind event is forecast to start this afternoon, with winds then quickly blasting to 30 kt late tonight through Wed with seas rapidly building to 11 ft by Wed afternoon. This event will be associated with a ridge building behind a cold front sliding S along the eastern slopes of the 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 active showers and thunderstorms expected to continue across much of Central America and the adjacent Pacific coastal waters. Long period cross-equatorial SW swell will maintain 5 to 8 ft seas across the forecast area during the next few days. Global weather models suggest the chance for low pressure to develop offshore of the coast of Guatemala or south of Gulf of Tehuantepec in the next few days, which will help to focus very heavy rainfall across the region. In the medium range, this low pressure system has a high chance of becoming a tropical cyclone during the next 5 days as it tracks WNW along the southern coast of Mexico.

REMAINDER OF THE AREA...

The pressure gradient between the high pressure ridge to the W of the Baja Peninsula and a cold front approaching from the W is generating fresh to strong southerly winds across the far NW waters, mainly N of 27N and within 150 nm east of the front. 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 30N138W to 27N140W today, and then from 30N138W to 27N138W to 25N140W as a weakening stationary front on Wed. Long period NW swell will follow the front and cause seas to build to between 8 and 10 ft generally N of 15N and W of 132W.

Satellite-derived wind and altimeter data confirmed the presence of moderate to fresh monsoonal flow over the forecast waters N of 07N and S of the monsoon trough. An area of 7 to 9 ft in long period SW swell is noted south of the monsoon trough and mainly between 97W and 115W, and is expected to prevail across this general area through through early Thu.

$$ Stripling

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