axpz20 knhc 241556
Tropical weather discussion
NWS National Hurricane Center Miami FL
1605 UTC Fri may 24 2013
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 1200 UTC surface analysis and satellite imagery through
A 1009 mb low is embedded within the monsoon trough near 10n106w
moving WNW 10 kt. This area of disturbed weather continues to
produce disorganized showers and thunderstorms. Latest satellite
imagery indicates that convection has diminished to the E and se
of the low center. Scattered moderate to isolated strong
convection is noted within 120 nm SW semicircle. The low is
underneath upper level ridging...and over rather warm sea
surface temperature. These ingredients may allow the low to
gradually intensify over the next 48 hours...with a medium
probability of tropical cyclone formation.
...Intertropical convergence zone/monsoon trough...
monsoon trough axis extends from 08n78w to low pres near 10n88w
1010 mb to low pres near 10n106w 1009mb to 08n120w. Scattered
moderate to isolated strong convection from 05n to 12n W of 125w.
A generally ridge-trough-ridge upper level pattern is analyzed
across the discussion area. The First Ridge extends N-NW from an
anticyclone located near 12n127w and is covering the waters W of
110w. The trough is along 30n120w 20n114w 11n116w. The Second
Ridge is broad in nature...and covers the area E of the trough.
Upper diffluence associated with this ridge is helping to induce
some clusters of moderate to strong convection very close to the
Pacific coast of Nicaragua...El Salvador and over the eastern
part of the Gulf of Tehuantepec...particularly N of 14n between
93w and 95w. The upper trough will move ewd today reaching the
NW part of Mexico as another and stronger upper level trough
reaches the far NW portion of the forecast area tonight.
At the surface...a 1031 mb high centered near 38n142w extends a
ridge sewd to near 20n118w. The tight pres gradient between the
ridge and low pres over the wrn U.S. Continues to result in
strong NW-N winds just N of the forecast waters. Under the
influence of this ridge...mainly NE winds of 15-20 kt are noted
N of the ITCZ and W of 120w.
The remnants of Alvin are still seen using night channel visible
images 11n136w. A trough is analyzed across the area and GOES
from 12n35w to beyond 9n140w. A modest region of fresh NE winds
around 20 kt continue N of this trough and are producing seas 8-
9 ft. This trough will continue W and exit the area later today.
Strengthening high pres across the Gulf of Mexico will produce a
brief gap wind event across the Gulf of Tehuantepec this
upcoming weekend. The forecast call for winds reaching 25 kt
with seas to 8 ft. Winds are also expected to briefly increase
to 25 kt across the Gulf of papagayo probably in association
with a developing low pres along the monsoon trough S of 10n.
Long period cross equatorial SW swell at 17-19 seconds dominates
most of the forecast waters E of 115w. Long period NW swell are
invading the NW waters.