000
AXPZ20 KNHC 050909
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE APR 05 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY 
THROUGH 0715 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ANALYZED FROM 08N78W 
TO 08N85W TO 03N97W TO 06N108W TO 01N140W. SCATTERED MODERATE 
CONVECTION WAS WITHIN 90 NM N AND 120 NM S OF THE ITCZ AXIS 
BETWEEN 88W AND 102W. ISOLATED MODERATE CONVECTION WAS WITHIN 60 
NM N OF THE ITCZ AXIS E OF 87W.

...DISCUSSION...

A WELL DEFINED UPPER LOW CENTERED NEAR 25N130W IS THE DOMINANT 
FEATURE OVER THE FORECAST AREA. THIS LOW HAS TAPPED INTO THE 
TROPICAL MOISTURE ALONG THE ITCZ AND HAS TRANSPORTED IT INTO ITS 
EASTERN SEMICIRCLE WITH SCATTERED MODERATE CONVECTION FOUND FROM 
09N TO 29N BETWEEN 119W AND 130W. THIS SYSTEM HAS DISRUPTED THE 
SUBTROPICAL HIGH PRES AND THE TRADE WINDS USUALLY FOUND OVER THE 
AREA. A SURFACE TROUGH ASSOCIATED WITH THE SYSTEM LIES FROM 
22N131W TO 11N136W. THE 0250 UTC WINDSAT AND 0614 UTC ASCAT 
PASSES SHOW A LARGE AREA OF 20 KT WINDS OVER NW WATERS N OF THE 
TROUGH WHERE THE PRES GRADIENT IS TIGHTEST BETWEEN THE TROUGH 
AND THE 1041 MB SUBTROPICAL HIGH NEAR 40N160W. 

THE PRES GRADIENT BETWEEN THE VAST SUBTROPICAL RIDGE AND LOWER 
PRES OVER NW MEXICO IS JUST STRONG ENOUGH TO SUPPORT 20 KT NW TO 
N WINDS WITHIN 120 NM OF THE W COAST OF BAJA CALIFORNIA AS SEEN 
BY SHIPS 3EUS AND SKWI. THESE CONDITIONS ARE EXPECTED TO CHANGE 
LITTLE THROUGH WED MORNING. BY LATE WED...THE UPPER LOW TO THE W 
WEAKENS AND MOVES NE OVER THE AREA. THIS WILL CAUSE ITS 
ASSOCIATED SURFACE TROUGH TO DISSIPATE...ALLOWING THE 
SUBTROPICAL RIDGING THE INCREASE OVER N WATERS AND SHIFT THE 
TIGHTEST PRES GRADIENT NORTHWARD OVER NE WATERS.

AN ANTICYCLONE ALOFT LIES NEAR 07N89W AND EXTENDS A RIDGE 
EASTWARD TO THE BORDER OF PANAMA AND COLOMBIA AND WESTWARD TO 
06N100W. UPPER DIFFLUENCE ASSOCIATED WITH THIS RIDGE IS 
ENHANCING CONVECTION ALONG THE EASTERN PORTION OF THE ITCZ IN A 
REGION WHERE PRECIPITABLE WATER VALES ARE AROUND 50 MILLIMETERS. 
THIS CONVECTION IS DESCRIBED IN THE ITCZ SECTION ABOVE. 

CROSS-EQUATORIAL SW SWELLS WILL KEEP SIGNIFICANT WAVE HEIGHTS IN 
THE 8-10 FT RANGE OVER S CENTRAL WATERS THROUGH THE FORECAST 
PERIOD.

GAP WINDS...
GULF OF CALIFORNIA...SW WINDS WILL PICK UP TO 20 KT OVER THE FAR 
NORTHERN GULF OVER NIGHT WED NIGHT AHEAD OF THE NEXT STRONG COLD 
FRONT MOVING THROUGH THE WESTERN CONUS.

GULF OF TEHUANTEPEC...STRONG HIGH PRES ASSOCIATED WITH A COLD 
FRONT EXPECTED TO SWEEP INTO THE SW GULF OF MEXICO TODAY WILL 
INITIATE A BRIEF GALE WIND EVENT THIS EVENING IN THE GULF OF 
TEHUANTEPEC THAT IS EXPECTED TO END BY SUNRISE WED.

GULF OF PAPAGAYO...THE 0246 UTC ASCAT PASS SHOWED A SMALL AREA 
OF 20 KT WINDS JUST W OF THE GULF OF PAPAGAYO CAUSED BY THE PRES 
GRADIENT BETWEEN RIDGING TO THE NE OVER THE NW CARIBBEAN AND 
TROUGHING OVER NORTHERN SOUTH AMERICA. THE PRES GRADIENT WILL 
SLACKEN THIS MORNING AS THE RIDGE SHIFTS EASTWARD...AND WINDS 
WILL DROP BELOW ADVISORY CRITERIA UNTIL EARLY WED MORNING WHEN 
THE COLD FRONT THAT BROUGHT THE GALE TO TEHUANTEPEC MOVES INTO 
THE AREA.

$$
SCHAUER