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AXPZ20 KNHC 162213
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 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 1800 UTC surface analysis and satellite imagery through 2100 UTC.


...SPECIAL FEATURES...

The center of Tropical Depression Tara is located near 19.0N 105.0W at 2100 UTC, or about 40 nm W of Manzanillo Mexico, drifting NW or 325 degrees at 2 kt. Estimated minimum central pressure is 1005 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. Scattered moderate to strong convection is noted surrounding Tara from 18N TO 22N and within 75 nm of the Mexican coast, and extending inland up to 30 nm. Upper level southeast winds and interaction with the mountainous coastal zone of Mexico have continued to weaken the small circulation of Tara today. Tara is not expected to re-strengthen and is now forecast to weaken to a 25 kt post-tropical remnant low within 24 hours, and then dissipate by 48 hours. Heavy rainfall will continue to impact the adjacent coastal areas through Wednesday. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCPEP2/WTPZ32 KNHC for more details.

Heavy rainfall will also continue to affect portions of Central America and southeast Mexico from western Panama to Oaxaca, Mexico for the next few days as broad low pressure prevails in the lower levels of the atmosphere. A Caribbean low pressure center moved inland this morning across Honduras and Belize and is pulling abundant tropical moisture with it. A long fetch of fresh to strong SW winds are also transporting tropical moisture from the tropical eastern Pacific into Central America. The combination of all this moisture and instability, and the potential development of yet another low during the next 48 hours between the Gulf of Papagayo and the Gulf of Tehuantepec will maintain very unsettle weather across the region. Consult your local meteorological service for details.


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

The monsoon trough extends over land from Panama to LOW PRES 1007 MB NEAR 16N89.5W TO 08.5N122W TO 11N129W to beyond 08.5N140W. Scattered moderate to strong convection is found from 03.5N to 12N E of 89W, and from 10N to 14.5N between 89W and 115W.


...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A 1023 mb high pressure system off the northern California coast extends SSE into the region to near the Revillagigedo Islands, and is maintaining moderate to locally fresh NW winds over the offshore forecast waters W of Baja California. The ridge 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 California: Strong NNW winds continue across the far northern Gulf of California and extends southward to about 30N, as strong high pressure persists over the Great Basin region of the United States. One last pulse of strong northerly winds are expected this evening before winds begin to gradually subside through Wed as the high moves E and weakens.

Gulf of Tehuantepec: The next gap wind event is forecast to start this evening, 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. These strong gap winds may continue for the next few days, and pulse to around 30 kt each night. Global models continue to suggest that another low pressure center will likely develop near the Pacific coast of Central America in the next few days, somewhere between the Papagayo region and Tehuantepec. The gap wind event across Tehuantepec will act to enhance this low level circulation as it shifts westward Wed or Thu...and there is a medium chance for a tropical cyclone to develop across this area within the next 48 hours, and a high chance to form within the next 5 days.

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 Wed, with active showers and thunderstorms expected to continue across much of Central America and the adjacent Pacific coastal waters and spread well inland. Long period cross-equatorial SW swell will maintain 5 to 8 ft seas across the forecast area during the next few days. As mentioned above, global weather models suggest the chance for low pressure to develop offshore of the coast between Papgayo and south of Gulf of Tehuantepec in the next few days, which will help to focus very heavy rainfall across the region.

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 28N 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 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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