Tropical Weather Discussion

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Tropical weather discussion 
NWS National Hurricane Center Miami FL
1005 UTC Thu Nov 23 2017

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 0600 UTC surface analysis and satellite imagery through 
0945 UTC.

...Special feature...

Gulf of Tehuantepec gale warning: 30 to 40 kt gale force winds 
will continue into early Thu afternoon with minimal gale 
conditions then persisting through mid morning on Fri. Winds 
will diminish to 20 kt or less late Sat morning. Expect Max seas 
of 17 ft near 14n96w tonight. The resultant NE swell will 
propagate SW, mixing with long- period cross equatorial swell, 
with seas 8 ft or higher well downstream of the Gulf of 
Tehuantepec along 08n between 95w and 105w on Fri night before 
beginning to subside. Expect winds 20 kt or less and seas less 
than 8 ft only briefly on Sat afternoon. Strong N winds are 
forecast to resume again on Sat evening with gale conditions 
just after sunrise on sun. Latest guidance is suggesting another 
30 to 40 kt event on Sun night with the gales diminishing late 
Mon.

Intertropical convergence zone/monsoon trough... 

The monsoon trough extends W between 09n and 11n across the SW 
Caribbean to the Pacific coast of Costa Rica at 09n84w, and 
continues W to 09n105w where scatterometer winds indicate a 
transition to an ITCZ, which continues NW to an embedded trough 
at 12n114w, then the ITCZ turns SW to beyond 07n140w. Isolated 
moderate to strong convection is noted within 90 nm either side 
of a line from 06n77w to 09n85w to 08n104w to 0n116w to 08n135w.

...Discussion...

Offshore waters within 250 nm of Mexico...

See special features paragraph above for information on the 
Gulf of Tehuantepec gale warnings. 

Light and variable winds and 2 to 4 ft seas expected W of baja 
today, then seas will build from the NW with 4 to 7 ft seas at 
13 to 15 seconds forecast across the waters W of baja on Fri 
night, then subsiding some on Sat into sun. Long-period NW swell 
in the form of 7 to 9 ft seas will reach 30n120w on Sun night, 
and spread S across the waters W of baja with 8 to 13 ft seas at 
17 to 19 seconds forecast W of baja Mon night and Tue.

Gulf of california: gentle to moderate NW flow expected through 
tonight. The pressure gradient will then relax, with light and 
variable winds on Fri through Mon. Strong to near gale NW flow 
expected to develop N of 25n on Mon night through Tue night,
with seas building to 12 ft across the long fetch waters.  

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

  
Gulf of fonseca...fresh NW winds forecast to begin around 
sunrise on Mon.  

Gulf of papagayo: fresh to locally strong NE nocturnal drainage 
flow forecast to begin tonight, with strong pulses through Tue. 
Seas of 8 ft or greater will propagate SW to neat 08n92w on 
Tue.

Light and variable winds, and 3 to 5 ft seas, are expected 
elsewhere through Sun night to the N of the monsoon trough which 
has been meandering between 09n and 11n.  Moderate NE flow 
expected N of the Gulf of papagayo early Mon. Moderate southerly 
winds, and 3 to 6 ft seas, are forecast S of the monsoon trough.

Remainder of the area... 

A cold front from 32n137w to 29n140w will stall today with a 
surface low developing along the front near 30n140w tonight. The 
low will move NE of the area on Fri night. Scattered moderate 
isolated strong convection is observed within 30 nm either 
sode of a line from 20n135w to 17n140w.

Combined seas of 8 to 13 ft at 14 to 16 seconds is currently 
observed across the discussion waters W of a line from 32n128w 
to 22n140w. This long period NW swell, in the form of 8 to 11 ft 
seas at 13 to 15 seconds, will propagate across the waters W of 
a line from 32n122w to 12n137w early Fri before beginning to 
subside. 

Another cold front will move E in to the area reaching from 
32n133w to 23n140w on Sat with 9 to 12 ft seas at 12 to 17 
seconds in the wake of the front.   

  
$$
Nelson


		
		

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