248 axpz20 knhc 072149 twdep

Tropical weather discussion  
NWS TPC/National Hurricane Center Miami FL
2205 UTC Sat Nov 07 2009
Tropical weather discussion for the eastern Pacific Ocean from 
the Equator to 32n...east of 140w. 
Based on 1800 UTC surface analysis and satellite imagery through 
2145 UTC.
...Tropical lows...
.Low pres is centered near 12.5n90w estimated at 1008 mb and is 
nearly stationary and mostly a swirl of low level clouds lacking 
convection.
.Low pres is centered near 12n118w estimated at 1010 mb and is 
moving slowly W at the moment. The surface low is under an upper
ridge and the associated upper diffluence has been enhancing 
intermittent convection which became a concern Fri night...but 
has since decreased considerably.
...ITCZ...
The ITCZ axis extends along 10n79w to 12n90w to 07n99w to 
12n118w to 08n140w. Scattered moderate convection is noted 
within 120 nm of 06n81w. Scattered moderate isolated and 
isolated strong convection is observed within 120 nm either side 
of line from 08n82w to 05n100w to 08n109w and also a line from
11n134w to 08n140w.
...Discussion...
A broad upper ridge dominates the tropics S of a line from 
00n135w to 20n120w to 00n108w. Debris moisture from convection W 
of the area is streaming E and NE to the NW periphery of the 
ridge merging with debris moisture from ITCZ near 08n138w...with 
the combined plume continuing NE and fanning out over the 
tropics from 14n to 22n between 120w and 135w. ITCZ convection 
is also enhanced along the ridge...from 10n to 15n between 118w 
and 110w...and also from 04n to 11n between 110w and 110w. Most 
of the debris moisture is spreading E and se...but the upper 
levels are so dry the moisture dries out fairly quickly. 
An upper trough is noted over the subtropics to the NW of the 
previously described tropical ridge...from 24n133w to 15n140w. 
An upper cyclone is over NW old Mexico near 28n111w. Dense upper 
moisture is observed over the NE semicircle of this cyclone and 
is spreading N across the SW conus. An upper trough extends se 
from this cyclone across Mexico to a base near 10n95w. Upper dry 
air is sweeping E across the discussion area from 25n to 28n 
between 140w and 120w then the dry air turns se through the 
upper trough and continues to push se right into the trough base.
An upper anticyclone is over the SW Caribbean near 14n82w with a 
ridge extending SW to near 06n88w. Convection was enhanced 
earlier under the ridge over NW Colombia and also over most of 
Panama and Costa Rica...and the debris moisture is now spreading 
SW over the discussion area near 05n82w.
At the low levels a ridge extends along 32n134w to 15n110w. 
Winds are generally 15 to 20 kt through the ridge. Large NW 
swells will spread into the area W of 105w well into next week.
Gap winds...
N winds at 20 to 25 kt expected to continue in and just 
downstream of the Gulf of Tehuantepec tonight into sun and 
finally diminishing below 20 kt late sun. 
$$
Nelson







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