AXPZ20 KNHC 112209 CCA

Tropical Weather Discussion...Corrected
NWS National Hurricane Center Miami FL
2205 UTC Mon Dec 11 2017

Corrected Offshore Waters Within 250 nm of Mexico section

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 2145 UTC.


Gulf of Tehuantepec Storm Warning: A very tight pressure gradient is sustained across the Isthmus of Tehuantepec by 1031 mb high pressure centered just west of Tampico Mexico. This tight pressure gradient will maintain strong gale force winds in the range of 30-40 kt over the Gulf of Tehuantepec until early on Tuesday, then diminish to minimal gale force by early on Wednesday. Seas are in the 12-18 ft range with these strong gale force, and will subside to 10-15 kt early in Tuesday and remain near those values through Wednesday. Fresh to strong NE-E winds extend downstream from the gulf to near 10N and 100W, where seas are in the 9-14 ft range primarily due to a NE swell. A large area of NE-E 15-20 kt winds is confined from 02N-15N between 90W- 110W, with seas of 8-12 ft in mixed NE and SW swell. This area is forecast to gradually shrink in coverage through Thursday.


The Monsoon Trough axis extends from NW Colombia to 08N78W to 07N84W to 05N90W where scatterometer data indicates the ITCZ begins and continues to 06N100W to 08N110W to 12N119W where it is bisected by a trough that is along a position from 20N114W to 10N113W. The ITCZ resumes at 10N124W to 10N132W to beyond the area at 08N140W. Scattered moderate convection is seen within 60 nm of the axis between 104W and 107W.



Gulf of Tehuantepec: Please see Special Features section above for details on the ongoing gale event.

A weaker pressure gradient than the past few days is presently over the SW U.S. This is maintaining generally gentle to moderate NW winds across the gulf. The gradient will between very strong high pressure that builds southward over the western U.S. and the thermal troughing will support the NW winds to increase over the northern portion of the gulf beginning on Tuesday, with winds there reaching the fresh category. These winds then increase further to the strong category on Wednesday and through Wednesday evening. Mainly moderate NW-N winds over the offshore Pacific waters along with seas of 4-6 ft will change little through Thursday.


Gulf of Papagayo: The tight pressure gradient over southeastern Mexico has slackened just enough to allow for the recent gale force NE winds that were present across the Gulf of Papagayo to diminish to strong to near gale force winds this morning. N-NE winds of 20-25 kt are elsewhere N of 08N between 85W-86W. Model guidance indicates that these winds will change little through Wednesday with seas in the range of 8-10 ft. These seas will propagate to the SW away from the fetch area and reach to near 08N and 98W on Thursday.


A dissipating stationary front is across the NW corner of the area from 30N136W to 28N140W. The main issue over the western half of the area is the long period NW swell that is located to the W of a line from 32N128W to 21N132W to 14N128W to 09N140W. The swell is inducing seas of 8-12 ft, with the highest of these seas N of 22N. The swell will gradually decay through Thursday, at which time it is forecast to be the W of a line from 32N134W to 23N140W along with seas of 8-11 ft.

The pressure difference between a trough roughly along a position from 20N114W to 10N113W and the high pressure over the northern and central waters is forecast to result in strong NE to E winds beginning late tonight from 13N-18N, and to the W of 128W along with seas of about 8-10 ft. This area of strong winds will diminish on Tuesday, with winds diminishing to 15-20 kt.

$$ Aguirre