000
AXPZ20 KNHC 052121
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE MAY 05 2009

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...07N77W TO 
07N105W TO 06N125W TO 09N140W. SCATTERED MODERATE CONVECTION IS 
WITHIN 30 NM EITHER SIDE OF THE ITCZ AXIS WEST OF 125W.

...DISCUSSION...

MODERATE DEEP LAYER WESTERLIES ARE NORTH OF 30N AND WILL RETREAT 
NORTHWARD TO NORTH OF 35N BY THE END OF THE WEEK.

A BROAD MOSTLY MIDDLE LEVEL RIDGE WILL EXTEND SOUTH OF THE 
WESTERLIES TO ABOUT 20N. SOUTH OF 20N A FLAT PATTERN WILL 
PREVAIL IN THE MIDDLE LEVELS WITH A WEAK TROUGH DEVELOPING SOUTH 
OF 20N ALONG 120W AT THE END OF THE WEEK.

IN THE UPPER LEVELS A CYCLONIC CIRCULATION IS CENTERED NEAR 
20N135W. A PLUME OF UPPER LEVEL MOISTURE WITH BROKEN HIGH CLOUDS 
EXTENDS WITHIN 500 NM IN THE NORTHEAST SEMICIRCLE AND ONLY THE 
MOISTURE WITHOUT THE CLOUDS WITHIN 200 NM OVER THE SW 
SEMICIRCLE. THIS FEATURE IS FORECAST TO PULL NORTH AND MOVE EAST 
NORTHEAST REACHING THE COAST OF SOUTHERN CALIFORNIA AT THE END 
OF THE WEEK.  

ANTHER UPPER TROUGH IS LOCATED ALONG 105W NORTH OF THE ITCZ. 
EAST OF THE TROUGH MOIST SOUTHER FLOW IS ADVECTING MAINLY HIGH 
CLOUDS OVER SOUTHERN MEXICO AND THE NORTHERN PART OF CENTRAL 
AMERICA.

AT THE SURFACE A WEAK TO MODERATE RIDGE IS NORTH OF THE ITCZ 
WEST OF 103W. THE RIDGE IS FORECAST TO STRENGTHEN SOME IN THE 
NEXT SEVERAL DAYS. REMAINDER OF THE LOWER LEVEL IS ANALYZED AS A 
WEAK TROUGH.

$$
LL