000
AXPZ20 KNHC 151542
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON JUN 15 2009

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1515 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N86W TO 06N115W TO 08N130W TO 
09N140W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION WITHIN 
90 NM N OF THE AXIS BETWEEN 98W AND 100W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION WITHIN 120 NM S OF THE AXIS BETWEEN 
95W AND 97W. SCATTERED MODERATE CONVECTION WITHIN 90 NM S OF 
AXIS BETWEEN 118W AND 120W.

...DISCUSSION...

SHIP AND SCATTEROMETER OBSERVATIONS FROM EARLIER THIS MORNING 
SHOW A WELL DEFINED SURFACE TROUGH FROM 30N125W TO 28N129W TO 
27N134W. THIS FEATURE IS ASSOCIATED WITH AN UPPER TROUGH 
EXTENDING FROM SOUTHERN CALIFORNIA TO 12N135W. THE SURFACE 
TROUGH DENTS A SURFACE RIDGE EXTENDING FROM A 1023 MB HIGH PRES 
AREA CENTERED NE OF HAWAII...TO THE BAJA PENINSULA. A SHIP W OF 
THE SOUTHERN TIP OF BAJA REPORTED NORTHERLY WINDS TO 25 KT AT 
12Z...A LITTLE HIGHER BUT BASICALLY IN LINE WITH 15 TO 20 KT 
FLOW NOTED ON A EARLIER ASCAT PASS. THIS FLOW IS BEING ENHANCED 
BY THE STILL TIGHT GRADIENT BETWEEN THE SURFACE RIDGE AND THE 
BAJA PENINSULA. GLOBAL MODELS SHOW THE UPPER TROUGH BECOMING 
MORE AMPLIFIED OVER THE NEXT COUPLE OF DAYS...WEAKENING THE 
SURFACE RIDGE FURTHER...AND ALLOWING THESE WINDS TO DIMINISH OFF 
THE BAJA COAST. FURTHER WEST...ASCAT DATA FROM AROUND 06Z SHOWED 
A SMALL AREA OF TRADES WINDS PERSISTING SOUTH OF THE SURFACE 
RIDGE...MAINLY W OF 135W. THIS PATCH OF ENHANCED TRADES WILL 
LIKELY PERSIST THROUGH LATE IN THE WEEK AS THE SURFACE RIDGE NE 
OF HAWAII REMAINS IN PLACE. MODEST CONVECTION IS NOTED ALONG THE 
ITCZ IN AN AREA OF UPPER DIVERGENCE AT THE BASE OF THE UPPER 
TROUGH NEAR 120W. DEEP LAYER MOISTURE WITH NORTHERLY MID AND 
UPPER FLOW ON THE WEST SIDE OF THE TROUGH IS TOO LIMITED TO 
SUPPORT SIGNIFICANT CONVECTION IN THIS AREA.

FURTHER EAST...UPPER LEVEL CYCLONIC TURNING SHOWS UP ON ANIMATED 
WATER VAPOR IMAGERY S OF THE GULF OF TEHUANTEPEC NEAR 14N95W. 
THIS IS SOUTHEAST OF AN UPPER ANTICYCLONE CENTERED OVER CENTRAL 
MEXICO NEAR 23N102W. THE DIVERGENCE ALOFT BETWEEN THE TWO UPPER 
FEATURES HAS BEEN INTERACTING WITH EARLY MORNING DRAINAGE FLOW 
OFF THE MEXICAN COAST TO ENHANCE SCATTERED CONVECTION WITHIN 90 
NM OF MEXICAN COAST BETWEEN 100W AND 104W. UPPER DIVERGENCE S OF 
THE UPPER CYCLONE IS ALSO ENHANCING CONVECTION ALONG THE ITCZ 
BETWEEN 95W AND 100W. MEANWHILE...CYCLONIC TURNING ALSO SHOWS UP 
NEAR 08N105W ALONG THE ITCZ...LIKELY MAINLY IN THE MID LEVELS.  
GLOBAL MODELS HINT THAT THE DOMINANT UPPER CYCLONE S OF 
TEHUANTEPEC DAMPENS OUT...AS THE MID LEVEL CYCLONE BECOMES 
DOMINANT. A 05Z ASCAT PASS HINTED OF 15 TO 20 KT CROSS 
EQUATORIAL SOUTHERLY FLOW INTO THIS AREA...INDICATED A SURFACE 
LOW MAY BE STARTING TO FORM. ALL MAJOR MODELS INDICATE A SURFACE 
LOW FORMING UNDER THE MID LEVEL CIRCULATION LATER TODAY...THEN 
SLOWLY SHIFTING NORTH. HOWEVER...NO MODEL IS HINTING ANY 
SIGNIFICANT DEVELOPMENT AT THIS TIME.

MEANWHILE...WW3 WAVE MODEL SHOWS LONG PERIOD SW SWELL WITH 
PERIODS UP TO 16 SECOND AND SIGNIFICANT WAVE HEIGHTS TO 5 FT 
PUSHING NE INTO THE COASTS OF MEXICO AND CENTRAL AMERICA TONIGHT 
THROUGH TUESDAY. 
 
$$
CHRISTENSEN