000
AXPZ20 KNHC 280930
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN JUN 28 2009

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 
0700 UTC.

...TROPICAL WAVE...

TROPICAL WAVE ALONG 90W/91W N OF 02N MOVING W 10 TO 15 KT. THE 
SOUTHERN PORTION OF THE WAVE IS ENHANCING CONVECTION OVER 
WESTERN NICARAGUA AND NW COSTA RICA AS WELL AS ALONG THE 
ITCZ...WITH SCATTERED MODERATE AND ISOLATED STRONG CONVECTION 
WITHIN 75 NM N AND 150 NM S OF THE ITCZ AXIS E OF 82W AND OVER 
FORECAST WATERS WITHIN 90 NM OF THE COAST FROM 10N TO 13N.  THE 
TROPICAL WAVE IS EXPECTED TO PASS THROUGH ACAPULCO BY MON 
EVENING.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 06N77W TO 09N88W TO 08N102W TO 
12N125W TO 06N140W. SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION CAN BE FOUND WITHIN 75 NM N AND 150 NM S OF THE AXIS 
E OF 82W AND WITHIN 60 NM OF THE AXIS W OF 132W. SCATTERED 
MODERATE CONVECTION CAN BE FOUND WITHIN 75 NM N AND 90 NM S OF 
THE AXIS BETWEEN 95W AND 101W AND WITHIN 120 NM N AND 75 NM S OF 
THE AXIS BETWEEN 108W AND 111W.

...DISCUSSION...

W OF 120W...
A SURFACE TROUGH EMBEDDED IN THE ITCZ LIES FROM 13N126W TO 
07N133W. THE QUIKSCAT PASS FROM 0320 UTC SHOWS WINDS TO 20 KT 
OVER FORECAST WATERS W OF THE TROUGH AXIS. THIS TROUGH LIES IN A 
REGION OF MODERATE UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER 
LEVEL RIDGE AXIS ALONG 17N W OF 120W AND AN INVERTED UPPER 
TROUGH S OF 20N ALONG 120W. SCATTERED MODERATE CONVECTION LIES 
WITHIN 180 NM E OF THE TROUGH AND WITHIN 60 NM OF THE ITCZ AXIS 
W OF 132W. THE SURFACE TROUGH WILL SLOWLY MIGRATE NW OVER THE 
NEXT FEW DAYS AS THE PATTERN BECOMES MORE AMPLIFIED. LOOK FOR 
THE UPPER TROUGH CURRENTLY CENTERED OVER NW WATERS N OF 20N 
ALONG 133W TO BE RELOADED BY THE MID LATITUDE TROUGH CURRENTLY 
BEARING DOWN ON HAWAII. THE SOUTHERLY FLOW ON THE LEADING EDGE 
OF THE AMPLIFYING UPPER LEVEL TROUGH SHOULD STEER THE MID-LEVEL 
ENERGY AND MOISTURE ASSOCIATED WITH THIS SURFACE TROUGH 
NORTHWARD AWAY FROM THE ITCZ. THE INCREASED TROUGHING ALOFT OVER 
NW WATERS WILL BREAKDOWN THE RIDGE AT THE SURFACE OVER THE NEXT 
FEW DAYS...DIMINISHING TRADE WINDS OVER THE REGION.

E OF 120W...
ASIDE FROM THE AFOREMENTIONED TROPICAL WAVE...THE MAJORITY OF 
THE DEEP CONVECTION E OF 120W LIES ALONG THE ITCZ. A REGION OF 
UPPER LEVEL DIFFLUENCE BETWEEN THE ANTICYCLONE OVER THE U.S. 
SOUTHERN PLAINS AND THE UPPER LOW MOVING INTO NE MEXICO HAS 
PROVIDED LIFT TO THE PLENTIFUL POOL OF ATMOSPHERIC MOISTURE OVER 
THE W COAST OF MEXICO. SCATTERED MODERATE COVNECTION CAN BE 
FOUND FROM 16N TO 22N BETWEEN 102W AND 106W AS A RESULT. THE 
WEAK MID LEVEL LOW NEAR THE SOUTHERN TIP OF BAJA CALIFORNIA WILL 
WEAKEN AND DRIFT SW OVER THE NEXT FEW DAYS. THIS SYSTEM IS IN A 
REGION OF RATHER STABLE ATMOSPHERIC CONDITIONS WHICH SHOULD 
LIMIT CONVECTION BUT THE MIGRATION OF THE LOW SHOULD HELP SPREAD 
SOME OF THE MOIST LOW TO MID LEVEL AIR FARTHER W. ELSEWHERE...A 
SECOND TROPICAL WAVE WILL MOVE FROM THE CARIBBEAN TROUGH THE 
GULF OF PANAMA ON MON.

S OF 05S...
SOUTHEAST TO S WINDS NEAR 20 KT ARE EXPECTED TO PERSIST S OF THE 
ITCZ PRIMARILY S OF 05N OVER THE NEXT FEW DAYS AS THE PRESSURE 
GRADIENT TIGHTENS BETWEEN THE SOUTHERN HEMPISPHERE SUBTROPICAL 
RIDGE AND THE ITCZ. SIGNIFICANT WAVE HEIGHTS ARE EXPECTED TO 
HOVER NEAR 8 FT ACROSS THIS AREA WITH LONG PERIOD SW SWELL 
MOVING THROUGH THE REGION PRIMARILY E OF 127W.

$$
SCHAUER CLARK