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Tropical weather discussion
NWS TPC/National Hurricane Center Miami FL
1005 UTC Tue Nov 10 2009
Tropical weather discussion for the eastern Pacific Ocean from
the Equator to 32n...east of 140w.
Based on 0600 UTC surface analysis and satellite imagery through
0730 UTC.
...ITCZ...
The ITCZ axis extends from 09n79w to 07n95w to 12n115w to
07n135w to 07n140w. Scattered moderate convection can be found
on either end of the ITCZ over forecast waters...specifically
within 120 nm either side of the ITCZ axis E of 86w and within
45 nm either side of the ITCZ axis W of 135w. Isolated moderate
convection can be found within 120 nm N of axis between 114w and
124w and within 120 nm S of axis between 110w and 114w. This
convection is in the vicinity of two surface troughs embedded in
the ITCZ from 13n122w to 08n126w and from 14n112w to
09n115w...respectively.
...Discussion...
A high pres ridge stemming from a 1022 mb high near 31n134w and
extending se to near 17n105w dominates north waters at the
surface. This high pres system is part of a larger North Pacific
ridge that is currently being compromised by a stationary front
just north of the forecast area. While this front is expected to
dissipate N of forecast waters today...long period NW swell from
the system has already pushed well into waters W of 105w and
significant wave heights have subsided to the 10 to 13 ft range
over much of this area. This swell will continue to slowly
subside to the 8 to 10 ft range over the next two days with
wind waves stemming from the easterly trade winds generally
found...according to the 0130 and 0310 UTC Quikscat
passes...from 10n to 20w W of 113w helping to keep wave heights
above 8 ft over much of the region. A new cold front will
approach NW waters overnight Wed night that will reinvigorate
the NW swell. The surface high pres over N waters will
reorganize to the NW in response to this cold front. The trade
winds are expected to shrink W and diminish to 20 kt over the
next few days as a result.
Broad upper level diffluence between a weak upper trough from
20n120w to 10n125w and an anticyclone centered near 12n105w is
enhancing convection along the ITCZ over waters between 110w and
125w. See the ITCZ section above for details on this
convection. The trough and anticyclone are both expected to
migrate E over the next two days.
Closer to shore...35 to 50 kt W-NW upper flow is inhibiting
convection over Mexico and adjacent waters N of 19n. To the
S...broad upper level diffluence between an anticyclone over the
NW Caribbean and troughing from northern Peru to just W of the
galapagos is enhancing convection over Panama and Costa Rica on
the eastern side of the ITCZ.
Gap winds...
the 0402 UTC ascat pass showed 20 to 30 kt winds funneling
through The Isthmus of Tehuantepec into the Pacific from the
western Gulf of Mexico on the western side of Atlantic Tropical
Storm Ida. N to NE winds in the Gulf of Tehuantepec will
increase to gale force by sunrise and persist through the
forecast period...with winds just below storm force expected Wed.
$$
Schauer
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