000
AXPZ20 KNHC 131554
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU MAY 13 2010

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 
1445 UTC.

...ITCZ...
AXIS ALONG 06N77W TO 06N130W TO 05N140W.  SCATTERED MODERATE TO 
ISOLATED STRONG CONVECTION WITHIN 90 NM N AND 120 NM S OF AXIS 
97W-102 AND 117W-130W.

...DISCUSSION...
UPPER LEVEL TROUGH EXTENDS FROM 32N122W TO 20N140W CARRIES VERY 
DRY AIR MASS WITHIN 300 W OF AXIS DUE TO STRONG CONFLUENT WINDS. 
UPPER LEVEL MOISTURE DIG S BEHIND TROUGH N OF 27N W OF 137W.  
JET CORE 95 KT AHEAD OF TROUGH COMBINES WITH DOWNSTREAM 
ANTICYCLONE TO TRAP SWATH OF TROPICAL CONVECTIVE ITCZ DEBRIS AND 
ADVECT IT E INTO CENTRAL MEXICO S OF 21N.

WEAK MID TO UPPER LEVEL ANTICYCLONE AT 08N116W HAS BROAD RIDGE 
EXTEND E TO 86W PROVIDING LITTLE SHEAR AND AMPLE OUTFLOW TO 
SPARK ITCZ DEEP CONVECTION THROUGHOUT ENTIRE BASIN.  WEAK 
DEFORMATION ZONE BETWEEN RIDGE AND A SECOND ONE OVER SOUTH 
AMERICA BRING DRY AIR S FROM COSTA RICA TO 00N85W INTERRUPTING 
ITCZ CONVECTIVE BELT.  OVER FAR EASTERN SECTION...MID TO UPPER 
LEVEL RIDGE EXTEND ALONG 06N E OF 82W INTO S AMERICA WITH UPPER 
LEVEL DIFFLUENCE UNDER RIDGE ENHANCING SCATTERED CONVECTION OVER 
PANAMA.

AT THE SURFACE...HIGH PRES CENTER AT 34N129W 1028 MB HAS RIDGE 
EXTEND SE TO 16N111W.  RIDGE SQUEEZES GRADIENT ALONG SOUTHERN 
CALIFORNIA COAST WITH FRESH N WINDS GOING AS FAR S AS 26N 
DIMINISH BELOW 20 KT THROUGH REST OF FORECAST PERIOD.  FRESH NE 
TRADES DIMINISH IN STRENGTH AND COVERAGE AS RIDGE WEAKENS AND 
HIGH PRES DRIFT SE.  MODEL GUIDANCE APPEAR CONSISTENT WITH THIS 
SCENARIO.  NE SWELLS PRODUCED BY TRADES REMAIN W OF 125W WHILE 
VERY LONG PERIOD SW SWELLS SPREAD THROUGH REMAINDER OF BASIN E 
OF 125W E OF 110W AND S OF 12N FROM 92W-130W.

WEAK TROUGH ALONG 83W N OF 02N UNDER SLIGHTLY FAVORABLE ENVIRON 
ALOFT SHOULD DRIFT INTO MORE ADVERSE CONDITIONS AND WEAKEN 
FURTHER.  NO SIGNS OF CYCLONIC ORGANIZATION NOTED.  

GAP WINDS...STRONG NE TO E BREEZE SURGING THROUGH GULF OF 
PAPAGAYO EXPECTED TO DIMINISH BELOW 20 KT WITHIN 48 HOURS AS 
WESTERN CARIBBEAN TRADES SUBSIDE.

$$
WALLY BARNES