axpz20 knhc 052153
Tropical weather discussion
NWS National Hurricane Center Miami FL
2205 UTC Mon Oct 05 2015
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
Based on 1800 UTC surface analysis and satellite imagery through
...Intertropical convergence zone/monsoon trough...
Monsoon trough axis extends from 07n78w to 12n98w to low pres
near 09n107w to 11n115w...then resumes from low pres near
16.5n122w to 09n130w to 13n140w. No ITCZ axis was noted.
Scattered moderate to strong convection was noted from 04n to
07n between 78w and 87w. Scattered moderate convection was
within 150 nm S of axis between 104w and 114w...and also from
10n to 13n between 128w and 132w.
Gulf of California...a cold front is moving through the northern
portion of the Gulf extending from 32n114w to 30n115w. An
afternoon ascat-a and b scatterometer passes missed the area of
winds in the far northern Gulf of California associated with the
cold front. The primarily front will continue eastward into
Mainland Mexico during the next 24 hours while troughing will
linger across NW baja through Tue morning allowing for fresh to
strong winds to linger in the far NW corner of the
Gulf...diminishing by Tue afternoon.
Gulf of Tehuantepec...a fairly tight pressure gradient is in
place across the area between 1018 mb high pressure NW Veracruz
Mexico and lower pressure associated with the monsoon trough
which has extended northward to near 12n98w. This combined with
nocturnal drainage flow supported a pocket of fresh to strong
northerly winds in the immediate Gulf earlier today. Nwp models
are forecasting a more impressive surge of northerly winds
tonight...peaking at 30 kt to near gale force by Tue morning.
These winds will build seas up to 8-11 ft. Similar conditions
are expected Tue night into Wed morning perhaps slightly weaker.
Later nwp model runs will be monitored for possible gale
Gulf of papagayo...high pressure ridging will prevail across The
Spine/interior of Central America. This combined with lower
pressures associated with the monsoon trough will induce fresh
NE-E winds in the Gulf by Tue morning with the aide of nocturnal
drainage flow. Winds are forecast to be slightly stronger by
sunrise Wed morning with winds up to strong levels.
The cold front that is currently moving through the northern
Gulf of California extends across Baja California norte and
offshore into the NE Pacific offshore waters from 29n115w to
24n123w. Scatterometer data indicated only light to moderate NW-
N winds behind the front...earlier altimeter data sampled seas
of 8 ft in NW-N swell which cover the waters roughly N of 26n
between 120w and 128w. The front will dissipate over the open
Pacific waters by 12 hours or so...and the northerly swell will
also subside to less than 8 ft later tonight.
High pressure ridging covers the NW and W central waters
reaching from near 32n139w to 14n128w. Meanwhile 1006 mb low
pressure is just W of the discussion waters near 14.5n144w.
Fresh E-se winds are flowing into the low circulation from the W
central waters and these winds combined with longer period
northerly swell are resulting in combined seas to 8 ft from 09n
to 16n W of 137w. Expect these seas to persist during the next
24-48 hours shifting to the area from 17n to 26n W of 138w with
se to S winds increasing to 20 to 25 kt in the same area by 48
A 1006 mb area of low pressure remains embedded in the monsoon
trough near 16.5n122w. Afternoon scatterometer data missed the
low pres area. Nwp models suggest 20 to 25 kt winds are still
occurring within 240 nm in the se semicircle. The low is
forecast to weaken during the next 24 hours with winds
diminishing to 20 kt or less...then will open up into a trough
from 22n123w to 13n130w by 48 hours with the area of residual 8
ft seas subsiding by then.
A large area of cross-equatorial SW swell surrounds the low and
covers the S central waters. The cross equatorial SW swell will
persist across the S central waters through 48 hours as a new
surge/set propagates across the Equator.