000
AXPZ20 KNHC 100917
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE MAY 10 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 
0822 UTC.

...ITCZ...
THE AXIS IS ANALYZED FROM LOW PRES 1005 MB NEAR 09N86W TO 
08N100W TO A SECOND LOW PRES 1009 MB TO 03N140W. NUMEROUS 
MODERATE SCATTERED STRONG CONVECTION WITHIN 60 N OF AXIS AND 150 
NM S OF AXIS BETWEEN 88W AND 92W. NUMEROUS MODERATE SCATTERED 
STRONG CONVECTION WITHIN 90 S OF AXIS BETWEEN 100W AND 102W. 
SCATTERED MODERATE CONVECTION WITHIN 120 NM N OF AXIS BETWEEN 
105W AND 120W.

...DISCUSSION...
AN UPPER RIDGE IS CENTERED NEAR 35N142W...ABOVE AN ASSOCIATED 
1030 MB SURFACE HIGH PRES AREA...AND NORTH OF AN UPPER CYCLONE 
NEAR 24N140W. A WEAK SURFACE TROUGH IS NOTED SOUTH OF THE 
SURFACE HIGH PRES...FROM 34N142W TO 30N137W. THIS IS SUPPRESSING 
TRADEWINDS BETWEEN 10N AND 15N WHERE A 06Z ASCAT PASS SHOWED 
WINDS MOSTLY BELOW 20 KT. SHIP AND WINDSAT DATA SHOW PERSISTENT 
FRESH NW FLOW ALONG THE BAJA COAST...BETWEEN THE HIGH PRES AND 
DEEP LOW PRES OVER NORTHERN MEXICO. 

FURTHER SOUTH...A PAIR OF UPPER SHORT WAVE TROUGHS HAVE BEEN 
MOVE EASTWARD SOUTH OF THE CUTOFF UPPER LOW...OCCASIONALLY 
COMING IN PHASE WITH COUPLE OF LOW LEVEL TROUGHS ALONG THE ITCZ. 
THIS INTERACTION AS RESULTED IN DEEPENING SURFACE PRES AND FLARE 
UPS OF CONVECTION NEAR THE SURFACE TROUGHS. A 1009 MB SURFACE 
LOW IS ANALYZED ALONG THE WESTERNMOST OF THIS TROUGHS NEAR 
08N116W WITH SCATTERED MODERATE CONVECTION. FURTHER EAST...THE 
OTHER TROUGH EXTENDS FROM 12N100W TO 06N101W. LOW PRES HAD 
FORMED OVER THIS TROUGH AS THE UPPER SHORT WAVE TROUGH 
APPROACHED...BUT HAS SINCE DISSIPATED. GLOBAL MODELS HINT THAT 
BOTH OF THESE FEATURES WILL PERSIST THROUGH 72 HOURS WITH LITTLE 
MOVEMENT WESTWARD BUT WITH SPORADIC CONVECTION...BETWEEN A 
BUILDING UPPER RIDGE TO THE EAST AND AN HIGHER AMPLITUDE UPPER 
TROUGH THAT WILL APPROACH FROM THE WEST LATER IN THE WEEK. MODEL 
CONSENSUS ALSO SHOW THE DEVELOPMENT OF ANOTHER WEAK SURFACE 
TROUGH FURTHER WEST ALONG THE ITCZ NEAR 135W OVER THE NEXT 24 TO 
48 HOURS IN ADVANCE OF THE DEEPENING UPPER TROUGH TO THE WEST. 
THESE SURFACE MAY ENHANCE TRADE WIND FLOW SLIGHTLY BETWEEN 10N 
AND 15N W OF 120W...BUT HIGH PRES TO THE NORTH WILL REMAIN WEAK 
THROUGH THE NEXT SEVERAL DAYS...SO WINDS WILL NOT REACH 20 KT 
FOR THE MOST PART. WITH NO LARGE SWELL ARRIVING FROM 
ELSEWHERE...SEA HEIGHTS WILL ALSO REMAIN LESS THAN 8 FT AS WELL.

EVEN FURTHER EAST...A 1008 MB LOW PRES AREA S OF COSTA RICA 
DEEPENED TO 1005 MB YESTERDAY EVENING AHEAD OF THE APPROACHING 
UPPER SHORT WAVE TROUGH AS IT DRIFTED SLOWLY NW. THIS FEATURE 
WILL LIKELY FILL AND OPEN INTO A WEAK TROUGH OVER THE NEXT 48 TO 
72 HOURS AS UPPER RIDGING BUILDS OVER THE FAR EASTERN PACIFIC. 

$$
CHRISTENSEN