000
AXPZ20 KNHC 121542
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1413 UTC Thu Dec 12 2019

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
1520 UTC.

...SPECIAL FEATURES...

Gale force N to NE winds continue this morning across the Gulf 
of Tehuantepec as cold air trapped behind a stationary front over
the western Gulf of Mexico continues to funnel S through the 
Chivela Pass. Overnight scatterometer data confirmed gales of 35 
to 40 kt across Tehuantepec that extended SSW to near 13.5N96W. 
These gale force winds peaked yesterday evening near 45 kt, with 
corresponding seas around 17 ft. Gale force winds will gradually 
diminish tonight through Thu, and are expected to taper off to 
strong then fresh Thu night through Fri. Gap winds will be below 
20 kt by Sat morning.

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

The monsoon trough extends from 09N74W to 09N81W to 06N94W to 
10N107W. The ITCZ continues from 10N107W to 09N121W. Low pres 
1010 mb is centered near 08N122W. The ITCZ resumes from 07N126W 
to beyond 06N140W. Scattered moderate and isolated strong 
convection is seen from 04N to 08N between 78W and 86W and within
an area bounded by 15N107W to 08N106W to 07N126W to 13N122W to 
15N107W.

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

1026 mb high pressure centered near 31N129W is maintaining 
moderate northerly flow off the coast of Baja California. Fresh 
to strong NW winds were evident overnight across the Gulf of 
California between 25N and 28N between the high pressure to the 
west and resident troughing over NW Mexico. Recent altimeter data
suggest seas hovering between 4 and 6 ft seas off the coast of 
Baja California and 3 to 5 ft seas in the central and southern 
Gulf of California. 

The high pressure will support moderate to occasionally fresh NW
winds off Baja California through Fri. New long period NW swell 
in excess of 8 ft will reach the waters around Guadalupe Island 
and the northern coast of Baja California Norte by tonight, then
reach the Revillagigedo Islands by late Sat. Looking ahead, a 
trough or weak front moving into the waters off northern Baja 
California Norte late Fri or Sat will generate fresh to strong 
NW winds in that area, but cause winds to diminish over the Gulf 
of California. Seas may reach 13 ft in NW swell in the open 
waters off Baja California. The front or trough will weaken as it
moves southward through Sun, but high pressure in the wake of 
this boundary will support another round of fresh to possibly 
strong N flow over the Gulf of California Mon and Tue.

Farther S, gentle to moderate winds and 3 to 5 ft seas will 
persist off the southern Mexico coast between Tehuantepec and 
Cabo Corrientes through Fri, then increase in the vicinity of 
Cabo Corrientes late Fri and Sat as the pressure gradient 
tightens. Large N to NE wind swell will propagate S and away from
Tehuantepec through tonight, even as winds diminish there. This 
will keep offshore seas at 6 to 9 ft across the far offshore 
waters south of Acapulco to Puerto Angel through Fri morning. 

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

Fresh NE to E winds will pulse to strong over the Gulf of 
Papagayo through Fri, then moderate to fresh winds are expected 
for the remainder of the forecast period. Elsewhere, gentle to 
moderate S to SW monsoon flow will persist across the offshore 
waters of Costa Rica, Panama, Colombia, and Ecuador through Sat 
night, while moderate NW to N flow prevails across the Gulf of 
Panama. 

REMAINDER OF THE AREA...

A 1026 mb high pressure center located near 31N129W is 
supporting fresh to strong trade winds across the waters south of
25N and west of 120W. Overnight altimeter data showed seas of 8 
to 11 ft in the area of fresh trades. The high will shift 
slightly SW through Thu night.

A weakening cold front will approach 30N140W, but stall today. 
Large NW swell generated earlier by gale force winds behind the 
front are spreading out to the SE of the front. Seas will build N
of the ITCZ and W of 120W, particularly where the longer period 
NW swell mixes with the shorter period NE to E trade wind swell. 
Seas will eventually peak between 12 and 14 ft tonight and Fri 
morning in this area. Westward moving areas of low pres will act 
to increase the pressure gradient S of the high and expand the 
area of strong trade winds to south of 26N and west of 120W.

$$
CAM