000
AXPZ20 KNHC 110343
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC MON MAY 11 2009

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE LIES ALONG A LINE FROM 06N77W 
TO 07N105W TO 04N125W TO 06N130W TO 06N140W. SCATTERED MODERATE 
CONVECTION IS WITHIN 60 NM OF THE POINT 07N81.5W. SCATTERED 
MODERATE WITH ISOLATED STRONG CONVECTION IS WITHIN 240 NM OF THE 
POINT 07.5N114W. SCATTERED MODERATE TO STRONG CONVECTION IS 
WITHIN 60 NM OF THE POINT 04.5N120W. SCATTERED MODERATE 
CONVECTION IS WITHIN THE AREA FROM 03N TO 05N FROM 122W TO 128W.

...DISCUSSION...

DEEP LAYER TROUGH IS OVER THE EASTERN PART OF THE AREA EAST OF A 
LINE THAT EXTENDS FROM THE YUCATAN PENINSULA NEAR 21N90W TO THE 
ITCZ NEAR 98W. THE AREAS IS DIFFLUENT ALOFT AND SUPPORTS 
ENHANCED CONVECTION MOSTLY IN THE ITCZ AND OVER THE DAYTIME 
HEATED AREAS OF CENTRAL AMERICA WHERE THE CONVECTION IS 
DIMINISHING DURING THE NIGHTTIME HOURS. THE RESULTING MULTI 
LEVEL CLOUDS FROM THE CONVECTION ARE ADVECTING NORTHWARD ACROSS 
MOST OF CENTRAL AMERICA. 

A LARGE CYCLONIC CIRCULATION IS CENTERED NEAR 21N121W AND COVERS 
AN AREA WEST OF 105W NORTH OF THE ITCZ TO A LINE ACROSS 
NORTHERN MEXICO FROM NEAR 30N105W TO 25N125W TO THE ITCZ NEAR 
125W. MOST OF THIS AREA IS DRY AND CLOUD FREE IN THE MIDDLE AND 
UPPER LEVELS EXCEPT FOR THE AREA EAST OF 115W WHERE MOIST 
SOUTHERLY FLOW IS OBSERVED. THE MOISTURE EMANATES FROM ENHANCE 
CONVECTION IN THE ITCZ NEAR 115W. THE CONVECTION IS SUPPORTED BY 
BOTH DIFFLUENT AIR ALOFT AND BY SURFACE CONVERGENCE ASSOCIATED 
WITH A SURFACE TROUGH THAT EXTENDS ALONG 115W FROM 10N TO 03N. 
THIS MOIST AIR IS FLOWING ACROSS MOST OF CENTRAL MEXICO EXCEPT 
FOR THE PART SOUTH OF 20N. CLOUDS ARE NOT PRESENT IN THIS MOIST 
FLOW AS IT MOVES FROM THE OCEAN TO THE CONTINENT BUT CONVECTION 
IS DEVELOPING AS THE AIR FLOWS OVER THE SIERRA MADRE OCCIDENTAL 
AND MULTI LEVEL CLOUDINESS IS ADVECTING OVER THE CENTRAL HIGH 
PLAINS OF MEXICO.  

A SMALLER CYCLONIC CIRCULATION IS LOCATED BEAR 26N132W AND IS 
MOVING NORTHEAST ABOUT 20 KT. LITTLE WEATHER IS ASSOCIATED WITH 
THIS FEATURE.

REMAINDER OF THE MIDDLE AND UPPER LEVELS IS UNDER BROAD 
ANTICYCLONIC FLOW.

MODERATE SURFACE RIDGE IS NORTH OF 17N WEST OF 120W WITH A 
WEAKER RIDGE ELSEWHERE NORTH OF 11N WEST OF 105W. EXCEPT FOR THE 
SURFACE TROUGH MENTIONED ABOVE WEAK TROUGH IS ANALYZED ELSEWHERE.

EASTERLY GAP WINDS IN THE GULF OF PAPAGAYO REGION WILL CONTINUE 
TO BE 15 TO 20 KT WITH BRIEF WINDS OF 25 KNOTS THROUGH THE NEXT 
SEVERAL DAYS. THE HIGHER WINDS SPEEDS WILL GENERALLY BE DURING 
THE NIGHTTIME HOURS.

$$
LL