000
AXPZ20 KNHC 310925
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU JAN 31 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 
METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM 09N85W TO 05N92W WHERE LOW LEVEL 
WINDS SUGGEST A TRANSITION TO ITCZ EXUDING TO 08N112W TO BEYOND 
05N140W. SCATTERED MODERATE CONVECTION WAS NOTED WITHIN 120 NM N 
OF THE ITCZ BETWEEN 115W AND 123W.

...DISCUSSION...
NEARLY STATIONARY 1035 MB HIGH PRESSURE IS CENTERED N OF THE 
AREA NEAR 40N132W WITH ASSOCIATED RIDGE EXTENDING OVER THE 
FORECAST WATERS FROM THE HIGH THROUGH 32N130W TO NEAR 16N110W. 
THE PRESSURE GRADIENT BETWEEN THIS AREA OF HIGH PRESSURE AND 
LOWER PRESSURE IN THE VICINITY OF THE ITCZ IS MAINTAINING FRESH 
TO STRONG TRADES OVER MUCH OF THE W CENTRAL PORTION OF THE 
FORECAST AREA FROM 06N TO 20N W OF 128W AND FROM 09N TO 15N 
BETWEEN 113W AND 128W. AN AREA OF 8-13 FT SEAS SURROUNDS THESE 
WINDS...WITH THE MAXIMUM SEAS OCCURRING COINCIDENT WITH THE 
STRONGEST WINDS. THE HIGH PRESSURE AND ATTENDANT RIDGE IS 
FORECAST TO WEAKEN DURING THE NEXT 24-48 HOURS WHILE SHIFTING 
FURTHER N OF THE AREA. AS A RESULT THE AREAL COVERAGE OF THE 
TRADE WINDS WILL DECREASE SIGNIFICANTLY...WITH WINDS DIMINISHING 
TO 20 KT OR LESS BY FRI EVENING.

THE PRESSURE GRADIENT BETWEEN THE RIDGE AND TROUGHING OVER 
WESTERN MEXICO IS RESULTING IN FRESH TO STRONG WINDS...EVEN 
ISOLATED AREAS OF WINDS TO NEAR GALE...IN THE GULF OF CALIFORNIA 
S OF 30N. SEAS OF 8 FT ARE SPILLING OUT OF THE MOUTH OF THE GULF 
TO 17N BETWEEN 105W AND 110W. WITH THE HIGH PRESSURE CENTER AND 
ASSOCIATE RIDGING WEAKENING TODAY...THE PRESSURE GRADIENT WILL 
RELAX AND WINDS WILL DIMINISH TO 20 KT OR LESS BY EARLY FRI 
MORNING.

GAP WINDS...
GULF OF TEHUANTEPEC...A STRONG COLD FRONT IN THE GULF OF MEXICO 
CURRENTLY EXTENDS FROM CENTRAL FLORIDA TO THE E BAY OF CAMPECHE. 
THE DENSER AIR MASS BEHIND THIS FRONT HAS STARTED TO FUNNEL 
THROUGH THE CHIVELA PASS INTO THE GULF OF TEHUANTEPEC. THE 
INITIAL SURGE WAS ACCOMPANIED BY A TYPICAL SIGNATURE ARC CLOUD 
THAT WAS EVIDENT IN SATELLITE IMAGERY. A GALE WARNING IS IN 
EFFECT OVER THE GULF OF TEHUANTEPEC...AND WAS CONFIRMED BY THE 
LATEST 0549 UTC OSCAT PASS DEPICTING 40 KT WINDS. WINDS ARE 
EXPECTED TO FURTHER INCREASE TO STRONG GALE FORCE BY 12-18 UTC 
TODAY. WITH A WARM EDDY IN THE GULF OF TEHUANTEPEC...IT IS 
POSSIBLE THAT MINIMAL STORM FORCE WINDS MAY BRIEFLY MIX TO THE 
SURFACE DURING THIS TIME. STRONG HIGH PRESSURE BUILDING BEHIND 
THE FRONT OVER EASTERN MEXICO AND THE WESTERN GULF OF MEXICO 
WILL HELP TO MAINTAIN GALE FORCE CONDITIONS IN THE GULF OF 
TEHUANTEPEC THROUGH EARLY SAT. 

GULF OF PAPAGAYO...FRESH TO STRONG WINDS OVER THE GULF OF 
PAPAGAYO WILL FURTHER INCREASE TO 30 KT BY EARLY FRI MORNING. 
THIS WILL BUILD SEAS TO 10 FT JUST DOWNWIND OF THE GULF.

GULF OF PANAMA...FRESH TO STRONG WINDS WILL SPREAD ACROSS THE 
ISTHMUS OF PANAMA FROM THE SW CARIBBEAN SEA TO THE GULF OF 
PANAMA BY LATE TONIGHT THROUGH FRI. THIS WILL RESULT IN SEAS 
BUILDING TO 8-9 FT DOWNWIND OF THE GULF.

$$
AL