AXPZ20 KNHC 180325
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Mon Feb 18 2019
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 0000 UTC surface analysis and satellite imagery through
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...Updated
A surface trough extends from northwestern Colombia to 04.5N83W
TO 05N94W TO 04N100W. The ITCZ begins from 04N100W TO 00N120W TO
00N130W. Widely scattered clusters of moderate convection are
noted within 150 nm N of the ITCZ between 104W and 111W.
OFFSHORE WATERS WITHIN 250 NM OF MEXICO...
A strong and persistent ridge extends southeastward across the
discussion area, from the NE Pacific through 32N136W to near
10N107W. The tight pressure gradient between the ridge and lower
surface pressure over the southwestern United States and Mexico
has been supporting strong northwest winds across the offshore
waters for over 24 hours, and have finally begun to diminish to
around 15-25 kt this evening as the ridge is realigning in
advance of an approaching cold front. Seas associated with these
winds are in 8-13 ft range in NNW swell, while these marine
conditions remain rough and dangerous.
A new cold front is sinking SSE across the offshore waters of
Southern California this evening and will sweep across far north
portions of Baja California tonight through Mon night and act to
reinforce this NW wind flow. However, this will also weaken
slightly the pressure gradient and lead to winds continuing to
slowly diminish to 15-20 kt across most of the waters by Mon
night, then become moderate to fresh Tue and Wed. Seas will also
gradually subside tonight through Mon as the current large NW
swell moves SE of the area. However, reinforcing NNW swell from
this next approaching cold front will maintain seas at 7-11 ft
Tue through Wed.
Gulf of California: Low pressure and its associated cold front
will move across the northern part of the Gulf of California
tonight, bringing fresh to strong SW to W winds to the northern
part of the Gulf of California ahead of the front tonight, and
then fresh to strong NW winds behind the front midday Mon
through Mon night. Fresh northerly wind flow is then expected
throughout most of the Gulf on Tue, diminishing to moderate to
locally fresh Tue night through Wed.
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...
Gentle northeast winds across the Gulf of Papagayo will increase
again to the mainly moderate speeds on Mon, and to stronger
speeds of fresh to moderate Mon night into Tue. Light and
variable winds are expected elsewhere through Tue, except for
the Gulf of Panama where moderate northerly winds are expected.
REMAINDER OF THE AREA...
A strong 1040 mb high pressure center, well to the north-
northeast of the Hawaiian Islands near 42N145W, will remain in
this general location through Wed. The associated ridge axis
extends southeastward through 32N136W to the tropics near
10N107W, which has forced the ITCZ southward to along the
equator. The pressure difference between this ridge and broad
low pressure lingering across the Hawaiian Islands area is
resulting in a tight pressure gradient across most of the area N
of about 08N and W of 110W. Northeast to east winds of 20 to 25
kt are generally west of a line from 30N140W TO 10N128W TO
09N128W TO 08.5N140W, where seas are in the range of 10 to 15
ft. This current overall synoptic pattern will change very
little through the next couple of days as low pressure north of
the Hawaiian Islands along 25N pulls northward and away from the
islands. The area of strong northeast to east winds will
persist, but over a gradually smaller section of the western
side of the discussion area. The seas there will slowly subside
to around the 10 to 12 ft through the next 48 hours as the large
swell gradually propagates SE of the area.