000
AXPZ20 KNHC 090257
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                          
0405 UTC TUE APR 09 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0145 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 09N84W TO 06N91W TO 
06N95W. THE ITCZ AXIS WAS ANALYZED FROM 06N95W TO 07N110W THEN 
CONTINUES FROM 05N115W TO 02N130W TO 01N140W. SCATTERED MODERATE 
CONVECTION WAS WITHIN 180 NM N OF THE AXIS BETWEEN 114W AND 
122W. A TROUGH BISECTS THE ITCZ FROM 09N109W TO 03N113W. 
SCATTERED MODERATE CONVECTION LIES WITHIN 180 NM EITHER SIDE OF 
THE TROUGH N OF 06N.

...DISCUSSION...                                             
GULF OF CALIFORNIA...A COLD FRONT WILL PASS THROUGH THE GULF OF 
CALIFORNIA N OF 29N TONIGHT. SOUTHERLY WINDS HAVE INCREASED TO A 
FRESH TO STRONG BREEZE AHEAD OF THE FRONT AND WILL SHIFT 
WESTERLY BEHIND THE FRONT. FUNNELING THROUGH MOUNTAIN PASSES 
WILL MAKE WINDS LOCALLY STRONGER...POSSIBLY TO GALE FORCE. WINDS 
WILL DIMINISH BY TUE MORNING AS THE FRONT RACES EASTWARD. A 
SECONDARY SURGE OF FRESH TO STRONG NORTHERLY WINDS WILL MOVE 
INTO THE NORTHERN GULF OF CALIFORNIA ON WED AND SPREAD SOUTHWARD 
ALONG THE GULF TO 26N BY WED EVENING. 

RELATIVELY ZONAL WESTERLY FLOW ASSOCIATED WITH A WIDE 90 KT 
UPPER JET CENTERED ALONG 20N E OF 125W INTO SOUTHERN MEXICO 
DOMINATES MUCH OF THE PACIFIC FORECAST AREA WITH A FEW 
EXCEPTIONS. TO THE W OF THE JET...AN UPPER TROUGH FROM 18N140W 
TO 00N125W IS CAUSING THE JET AXIS TO DIP SOUTHWARD OVER W 
WATERS AND TAP INTO TROPICAL MOISTURE ALOFT. THIS MOISTURE IS 
MANIFESTED AS CIRRUS FROM 08N TO 23N W OF 120W. TO THE S OF THE 
JET...UPPER DIFFLUENCE TO THE W OF AN ANTICYCLONE CENTERED NEAR 
10N101W IS ENHANCING SCATTERED MODERATE CONVECTION NEAR A 
SURFACE TROUGH FOUND FROM 09N109W TO 03N113W. THIS CONVECTION IS 
DESCRIBED IN THE SECTION ABOVE. TO THE N OF THE JET...A DEEP-
LAYERED TROUGH HAS MOVED INTO THE BAJA CALIFORNIA PENINSULA AND 
NORTHWESTERN MEXICO AND HAS DIRECTED UPPER WINDS MORE 
NORTHWESTERLY OVER FORECAST WATERS N OF 25N E OF 130W. THE 
NORTHERN STREAM JET ASSOCIATED WITH THIS TROUGH WILL MERGE WITH 
THE ZONAL JET OVER MEXICO OVER THE NEXT 48 HOURS.

THE 1030 MB SUBTROPICAL SURFACE HIGH LIES NEAR 36N133W AND 
EXTENDS A RIDGE SOUTHEASTWARD THROUGH 26N127W TO 16N110W. THE 
PRESSURE GRADIENT BETWEEN THE SUBTROPICAL RIDGE AND THE ITCZ IS 
FORCING FRESH TO STRONG NE TRADE WINDS FROM 09N-22N W OF 130W AS 
SEEN BY THE 1958 UTC ASCAT PASS AND THE 2030 UTC OSCAT PASS. THE 
HIGH IS EXPECTED TO REMAIN RELATIVELY STATIONARY AND SHOW LITTLE 
CHANGE IN PRESSURE THROUGH WED. 

THE PRESSURE GRADIENT ON THE E SIDE OF THE SUBTROPICAL RIDGE IS 
FORCING FRESH TO STRONG NW WINDS N OF 27N ALONG THE PACIFIC 
COAST OF THE BAJA CALIFORNIA PENINSULA TO 127W AS SEEN BY THE 
2028 UTC OSCAT PASS. A GALE WARNING IS IN EFFECT FOR WATERS N OF 
30N TONIGHT INTO TUE. 15-17 SECOND PERIOD NW SWELL CURRENTLY 
LIES OFF THE BAJA CALIFORNIA PACIFIC COAST. THIS DAMPENING NW 
SWELL IS COMBINING WITH NW WIND WAVES IN PACIFIC WATERS OFF THE 
BAJA CALIFORNIA PENINSULA...WITH SEAS EXPECTED TO REACH OVER 15 
FT S OF 30N OVERNIGHT TONIGHT AND BEGIN TO SUBSIDE ON TUE. THE 
LEADING EDGE OF THE NW SWELL TRAIN...WITH PERIODS EXCEEDING 20 
SECONDS...HAS ALREADY CLIPPED THE CENTRAL MEXICAN COAST NEAR 
CABO CORRIENTES AND WILL REACH THE GALAPAGOS ISLAND BY TUE 
AFTERNOON.

$$
SCHAUER