000
AXPZ20 KNHC 051542
TWDEP 

TROPICAL WEATHER DISCUSSION                                   
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1605 UTC THU APR 04 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              
MONSOON TROUGH FROM 08N78W TO 04N92W TO 05N105W. ITCZ AXIS FROM 
05N105W TO 02N140W. SCATTERED MODERATE CONVECTION WITHIN 60 NM S 
OF MONSOON TROUGH AXIS BETWEEN 80W AND 95W. SCATTERED MODERATE 
CONVECTION WITHIN 90 NM N OF ITCZ AXIS BETWEEN 105W AND 120W. 
                                             
...DISCUSSION...                                                
GULF OF TEHUANTEPEC...THE MOST RECENT LAND BASED OBSERVATIONS 
FROM SALINA CRUZ INDICATES STRONG GAP WIND FLOW IS UNDERWAY INTO 
THE GULF OF TEHUANTEPEC. GUSTS ON THE NORTHERN END OF THE 
ISTHMUS REACHED 38 KT YESTERDAY EVENING...INDICATIVE OF STRONGER 
FLOW IN THE LOWER LEVELS OF THE ATMOSPHERE THAT CAN MIX TO THE 
SURFACE OVER GULF OF TEHUANTEPEC.WITH THAT IN MIND...GALE 
CONDITIONS ARE EXPECTED TO START BY EARLY AFTERNOON. THE 
STRONGER WINDS ARE ASSOCIATED WITH A COLD FRONT THAT PUSHED 
THROUGH THE GULF OF MEXICO OVER THE PAST 24 HOURS. HIGH PRES 
BUILDING BEHIND THE FRONT OVER THE WESTERN GULF OF MEXICO TODAY 
WILL MAINTAIN A TIGHT ENOUGH GRADIENT TO ALLOW THE GALE 
CONDITIONS TO PERSIST THROUGH EARLY SAT. THROUGH THE REMAINDER 
OF THE WEEKEND...AS THE AIRMASS MODIFIES AND THE HIGH PRES 
WEAKENS AND SHIFTS E...WINDS ACROSS TEHUANTEPEC WILL DIMINISH. 

FARTHER W...A SURFACE RIDGE IS BUILDING ALONG ROUGHLY 28N...AS 
AN UPPER SHORT WAVE TROUGH EXITS TO THE NE OVER CALIFORNIA. THE 
RIDGE WILL ALLOW NW TO N WINDS OFF THE NORTHERN COAST OF BAJA TO 
INCREASE STARTING THIS AFTERNOON...WITH 20 TO 25 KT COVERING THE 
AREA N OF 27N E OF 125W. MEANWHILE THE EXITING TROUGH ALOFT WILL 
LEAVE A CUT OFF MID TO UPPER LOW NEAR 20N140W...S OF A BUILDING 
MID/UPPER RIDGE TO FORM A BLOCKING PATTERN ALONG 140W TO 145W 
THROUGH EARLY NEXT WEEK. THIS WILL SUSTAIN STRONG BOUNDARY LAYER 
RIDGE ALONG 28N...WHICH IN TURN WILL SUPPORT FRESH TO STRONG 
TRADE WIND FLOW S OF 20N W OF 120W. 

LIGHT CROSS-EQUATORIAL SOUTHERLY FLOW E OF 110W IS PROVIDING 
ENOUGH LOW LEVEL CONVERGENCE TO ALLOW CLUSTERS OF CONVECTION 
ALONG THE ITCZ AND MONSOON TROUGH...WITH THE STRONGEST 
CONVECTION OFF THE COAST OF COLOMBIA NEAR THE PANAMANIAN BORDER 
BENEFITING IN PART DUE TO OVERNIGHT DRAINAGE IMPACTS.

NW SWELL WITH PERIODS EXCEEDING 20 SECONDS WILL MOVE INTO NW 
WATERS ON TODAY. SEAS THERE ARE EXPECTED TO BUILD TO 11 FT BY 
SAT MORNING. THE LEADING EDGE OF THE SWELL WILL PROGRESS 
SOUTHEASTWARD....REACHING THE NORTHERN BAJA COAST ON SAT.

$$
CHRISTENSEN