000
AXPZ20 KNHC 302205
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED DEC 30 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 EXTENDS FROM 06N85W TO 04N98W TO 08N108W TO 06N120W TO
06N130W TO BEYOND 05N140W. NO SIGNIFICANT CONVECTION NOTED.

...DISCUSSION...                                              

HIGH PRESSURE DOMINATES MOST OF THE REGION WITH A 1027 MB HIGH
CENTERED N OF THE DISCUSSION AREA NEAR 34N127W. A RIDGE EXTENDS
FROM THE HIGH SE TO 32N123W TO NEAR 22N115W. THE PRESSURE
GRADIENT BETWEEN THIS HIGH PRESSURE AND LOWER PRESSURE IN THE
VICINITY OF THE ITCZ...AND WITH THE ADDED FACTOR OF A SURFACE
TROUGH ALONG A POSITION FROM 14N124W TO 08N126W CONTINUES TO
SUPPORT AN AREA OF FRESH TO STRONG TRADE WINDS WITHIN 180 NM W
OF THE TROUGH...AND ELSEWHERE FROM 08N TO 14N BETWEEN 125W AND
138W WITH SEAS IN THE 9-10 FT RANGE...EXCEPT FOR A BATCH OF 10-
11 FT SEAS ATTRIBUTED TO LONG DURATION NW SWELL FROM 07N-10N W
OF 130W. SCATTERED MODERATE CONVECTION IS SEEN WITHIN 45 NM W OF
THE TROUGH FROM 09N-11N.

A SHORTWAVE UPPER TROUGH ALONG 129W/130W IS RAPIDLY MOVING
EASTWARD. THE TROUGH WILL MOVE OVER THE AFOREMENTIONED SURFACE
TROUGH TONIGHT AND EARLY THU. THIS WILL HELP MAINTAIN THE
PRESENT GRADIENT THAT IS PRODUCING FRESH TO STRONG NE TRADES W
OF THE TROUGH WITH SEAS IN THE RANGE OF 9-10 FT. AS THE
SHORTWAVE TROUGH PULLS OFF TO THE NE THROUGH FRI...EXPECT THE
SURFACE TROUGH TO WEAKEN AND DISSIPATE. THE HIGH PRESSURE N OF
THE AREA IS FORECAST TO GRADUALLY SHIFT EASTWARD THROUGH THU AS
A COLD FRONT MOVES INTO THE NW CORNER OF THE DISCUSSION AREA.
THIS FRONT WILL WEAKEN AS IT REACHES A POSITION FROM NEAR
32N134W TO 25N137W BY LATE THU NIGHT...THEN BECOME A DISSIPATING
FRONT FROM NEAR 32N129W TO 19N140W FRI. NW SWELL WILL FOLLOW
INTO THE NW CORNER OF THE AREA WITH RESULTANT SEAS OF 8-9 FT.
THE NWP MODELS ARE SUGGESTING THAT A STRONG COLD FRONT WILL MOVE
INTO THE NW PORTION OF THE AREA FRI NIGHT INTO SAT PRECEDED BY
STRONG SW WINDS AND BUILDING SEAS...AND FOLLOWED BY POSSIBLE
GALE FORCE W TO NW WINDS AS DEPICTED IN THE LATEST RUNS OF THE
GFS...ECMWF AND UKMET.   

CROSS-EQUATORIAL SWELL WITH SEAS OF 8-9 FT ARE S OF 02N BETWEEN
108W-119W. THIS AREA OF SWELL WILL EXPAND E TO E THROUGH THE
NEXT 24 HOURS...THEN BE CONFINED TO S OF 04N BETWEEN 111W-120W
BY EARLY FRI.

GAP WINDS...

GULF OF TEHUANTEPEC...THE NEXT PULSE OF N TO NE WINDS IN THE
GULF OF TEHUANTEPEC IS EXPECTED TO BEGIN LATE TONIGHT WITH WINDS
OF 20-25 KT WITH WINDS REACHING 30 KT DURING THE MAXIMUM
DRAINAGE FLOW EARLY ON THU. THESE WINDS ARE EXPECTED TO REMAIN
STRONG TO NEAR GALE WITH SEAS REACHING A MAX OF AROUND 11 FT
UNTIL THE NEXT GALE FORCE GAP WIND EVENT ARRIVES LATE FRI NIGHT
INTO SAT AS A REINFORCING PUSH OF COLD AIR SPREADS ACROSS THE
WESTERN GULF OF MEXICO.

GULFS OF PAPAGAYO AND PANAMA...STRONG TO GALE FORCE TRADES
ACROSS HE SW CARIBBEAN SEA IS RESULTING IN PULSES OF STRONG NE-E
GAP WINDS THROUGH THE GULF OF PAPAGAYO. THESE WINDS WILL
DIMINISH TO 15-20 KT THIS AFTERNOON...THEN RETURN AS STRONG NE
WINDS EARLY ON THU. THEY WILL DIMINISH AGAIN THU AFTERNOON...
AND MATERIALIZE THU NIGHT. THE CARIBBEAN WINDS WILL ALSO USHER
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