000
AXPZ20 KNHC 300916
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU APR 30 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 
0900 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...04N78W TO 
04N110W TO 06N140W. A LARGE AREA OF SCATTERED MODERATE TO STRONG 
CONVECTION IS WITHIN THE AREA 100 NM EITHER SIDE OF A LINE FROM 
07.5N118W TO 09.5N130W. SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION IS WITHIN 60 NM OF THE POINT 06N139W.

...DISCUSSION...

MODERATE WEST TO SOUTHWEST DEEP LAYER FLOW IS NORTH OF A LINE 
FROM THE BIG BEND OF TEXAS TO ACROSS CENTRAL BAJA CALIFORNIA TO 
25N130W TO 16N140W. A STRONG SHORTWAVE IS JUST WEST OF THE 
REGION WITH A TROUGH AXIS NEAR 143W. THIS SHORTWAVE IS FORECAST 
TO MOVE EAST WITH THE TROUGH AXIS ALONG 140W MIDDAY TODAY. 
THE TROUGH WILL CONTINUE EAST BUT BECOME ABSORBED BY THE 
WESTERLIES NORTH OF 26N IN THE LATER PART OF THE WEEK. WEST OF 
125W A DEEP LAYER PLUME OF MOISTURE WITH BROKEN HIGH CLOUDS IS 
WITHIN 500 NM SOUTH AND SOUTHEAST OF THE WEST TO SOUTHWEST DEEP 
LAYER FLOW. ALSO ASSOCIATED WITH THE STRONG SHORTWAVE IS ANOTHER 
PLUME OF DEEP LAYER MOISTURE WITH MULTI LEVEL OVERCAST CLOUDS 
WITH SOME EMBEDDED CONVECTION WHICH IS AFFECTING THE AREA 
NORTHWEST OF A LINE THROUGH 32N131W TO 25N135W TO 18N140W. AS 
THE TROUGH MOVES EAST THIS AREA OF WEATHER WILL CONTINUE TO MOVE 
EAST ACROSS THE AREA MOSTLY NORTH OF 23N BUT AS THE TROUGH IS 
ABSORBED THE AREA WILL DIMINISH IN SIZE.

ANOTHER MAINLY UPPER TROUGH IS OVER THE EASTERN PART OF THE AREA 
EAST OF 105W WITH AN AXIS ALONG 96W. TO THE EAST OF THE TROUGH 
AXIS THE SOUTHERLY FLOW IS ADVECTING DEEP LAYER MOISTURE WITH 
MULTI LEVEL BROKEN CLOUDS FROM ITCZ CONVECTION TO OVER CENTRAL 
AMERICA AND EASTERN MEXICO. A WEAK SURFACE TROUGH HAS FORMED IN 
THE AREA ALONG 88W. THE CONVECTION IN THIS AREA HAS DIMINISHED 
IN THE LAST 6 HOURS.

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

A SURFACE TROUGH ASSOCIATED WITH THE DEEP LAYER TROUGH IS OVER 
THE FAR NORTHWEST PART OF THE AREA WITH ASSOCIATED SCATTERED 
MODERATE CONVECTION N OF 25N W OF 135W. ELSEWHERE A SURFACE 
RIDGE IS NORTH OF 12N WEST OF 105W. REMAINDER OF THE SURFACE IS 
ANALYZED AS A BROAD TROUGH.

GAP NORTHEAST TO EAST WINDS OF 20 TO OCCASIONALLY 25 KNOTS IN THE
GULF OF PAPAGAYO REGION WILL CONTINUE THROUGH TONIGHT THEN 
DIMINISH TO LESS THAN 20 KT FRIDAY.

$$
LL