000
AXPZ20 KNHC 292202
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE DEC 29 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
METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2145 UTC.   

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...         

ITCZ AXIS FROM 06N92W TO 06N110W TO 05N119W TO BEYOND 04N140W.
SCATTERED MODERATE ISOLATED STRONG WITHIN 180 NM N OF AXIS
BETWEEN 127W AND 134W.

...DISCUSSION...                                              

IN GENERAL...BENIGN CONDITIONS CONTINUE ACROSS THE AREA AS HIGH
PRESSURE DOMINATES. A 1025 MB HIGH PRESSURE SYSTEM IS CENTERED N
OF THE DISCUSSION AREA NEAR 37N134W WITH A RIDGE STRETCHING SE
TO 32N130W TO NEAR 20N110W. A WEAKENING SURFACE TROUGH
ASSOCIATED WITH A LARGE UPPER TROUGH THAT IS MOVING EASTWARD
ACROSS THE WESTERN U.S. IS ANALYZED OVER THE FAR NE PORTION OF
THE AREA EXTENDING FROM A 1012 MB LOW OVER WESTERN ARIZONA SSW
TO FAR NW MEXICO...AND ACROSS THE NORTHERN GULF OF CALIFORNIA
AND BAJA CALIFORNIA NORTE TO NEAR 27N113W. THE TROUGH IS
FORECAST TO SHIFT EASTWARD OVER NW MEXICO AND DISSIPATE TONIGHT.
THE PRESSURE GRADIENT BETWEEN THE TROUGH AND THE 1026 MB HIGH
HAS RELAXED AND ALLOWED NW WINDS TO DROP BELOW 20 KT OVER THE
FAR NE PACIFIC AND THE GULF OF CALIFORNIA. 

THE PRESSURE GRADIENT BETWEEN THE HIGH PRESSURE CENTERED N OF
THE AREA AND LOWER PRESSURE IN THE VICINITY OF THE ITCZ
CONTINUES TO SUPPORT AN AREA OF FRESH TO STRONG TRADE WINDS FROM
08N-21N W OF 130W...AND FROM 09N-20N BETWEEN 120W-130W WITH SEAS
IN THE 8 TO 10 FT RANGE...EXCEPT FOR HIGHER SEAS OF 10 TO 11 FT
PRIMARILY IN NW SWELL FROM 14N-21N W OF 135W. THE 1026 MB HIGH N
OF THE AREA IS FORECAST TO GRADUALLY SHIFT EASTWARD THROUGH THU
WHILE A WEAK LOW-LEVEL TROUGH IS FORECAST TO BECOME REFLECTED AT
THE SURFACE FROM 14N122W TO 10N125W EARLY WED. MOST OF THE
FORCING WILL BE PROVIDED BY A SHARPENING MID/UPPER TROUGH
CURRENTLY CROSSING 140W. NE WINDS OF 20-25 KT ARE EXPECTED
WITHIN 180 NM W OF THE TROUGH THROUGH THU. 

THE PRESSURE GRADIENT BETWEEN THE SURFACE TROUGH AND RIDGING N
OF THE ITCZ REGION WILL INDUCE NE 20-25 KT WINDS WITH SEAS IN
THE RANGE OF 9 TO 10 FT WITHIN 150-180 NM W OF THE TROUGH
THROUGH 48 HOURS AS IT REACHES TO NEAR 124W/125W BY THEN. AN
EXTENSIVE AREA OF MIXED NE AND NW SWELL WITH PRODUCED SEAS OF 8-
11 FT EXISTING TO N OF 09N BETWEEN 121W-129W...AND N OF 05N W OF
129W WILL SHRINK IN COVERAGE WHILE SLOWLY SHIFTING SOUTHWARD
THROUGH 48 HOURS... AT WHICH TIME IT WILL BE FORECAST TO BE
PRESENT OUTSIDE THOSE CONDITIONS RELATED TO THE AFOREMENTIONED
SURFACE TROUGH WITHIN 360 NM EITHER SIDE OF A LINE FROM 14N112W
TO 12N127W TO 10N131W TO 08N140W WITH HIGHEST SEA UP TO 10 FT
FROM 11N-13N BETWEEN 117W AND 126W.

SOUTHERLY SWELL WILL BRING 8 FT SEAS TO THE EQUATOR BETWEEN 108W
AND 119W LATE TONIGHT AND N OF THE EQUATOR BY WED MORNING. THESE
8 FT SEAS WILL SHIFT W THROUGH WED NIGHT AND PERSIST THROUGH THU.

GAP WINDS...

GULF OF TEHUANTEPEC...THE CURRENT PULSE OF N-NE WINDS HAS
DIMINISHED TO LESS THAN 20 KT AND REMAIN SO THROUGH WED. BY LATE
WED NIGHT....ANOTHER GAP WIND PULSE IS EXPECTED TO BEGIN
FOLLOWED BY ANOTHER GALE FORCE GAP WIND EVENT FRI NIGHT AS A
REINFORCING PUSH OF COLD AIR OCCURS ACROSS THE WESTERN GULF OF
MEXICO.

GULF OF PAPAGAYO...STRONG TO GALE FORCE EASTERLY TRADE WIND FLOW
ACROSS THE SW CARIBBEAN SEA IS RESULTING IN PULSES OF STRONG
EASTERLY GAP WINDS THROUGH THE GULF OF PAPAGAYO THAT WILL PULSE
DURING THE OVERNIGHT HOURS THROUGH SAT. THE CARIBBEAN WINDS WILL
ALSO SEND PULSES OF MODERATE TO FRESH NORTHERLY GAP WINDS ACROSS
THE ISTHMUS OF PANAMA INTO THE GULF OF PANAMA DURING THE EVENING
TO EARLY MORNING HOURS THROUGH SAT.

$$
COBB