000
AXPZ20 KNHC 271521
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON JUL 27 2009

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 
1500 UTC.

...TROPICAL WAVES...

THE TROPICAL WAVE PREVIOUSLY ALONG 96W AND THE TROPICAL WAVE 
PREVIOUSLY ALONG 105W HAVE BEEN READJUSTED TO A TROPICAL WAVE 
FROM 05N TO 17N ALONG 103W. IT IS ESTIMATED THAT THE WAVE WILL 
MOVE WEST 15 KT. S OF 13N SCATTERED MODERATE WITH ISOLATED 
STRONG CONVECTION IS WITHIN 200 NM W OF THE WAVE AXIS. NORTH OF 
13N AN AREA OF SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION IS WITHIN 200 NM OFFSHORE THE COAST OF MEXICO FROM 
98W TO 105W. CYCLONIC TURNING IS OBSERVED IN THE LOW CLOUDS 
SOUTH OF 13N AND A CIRCULATION CENTER MAY BE FORMING. THE 
COMPUTER MODELS FORECAST SOME DEVELOPMENT OF THIS FEATURE. UPPER 
LEVEL FLOW IS WEAKLY DIFFLUENT WITH LITTLE SHEAR.
 
TROPICAL WAVE FROM 05N TO 17N ALONG 121W MOVING W 15 KT. 
CONVECTION HAS INCREASED IN THE LAST 24 HOURS WITH SCATTERED 
MODERATE TO STRONG CONVECTION WITHIN 240 NM EAST OF THE WAVE 
AXIS. THE CONVECTION DOES NOT APPEAR TO BE ORGANIZED BY ANY LOW 
LEVEL CYCLONIC CIRCULATION. SOUTHERLY UPPER LEVEL FLOW IS 
CAUSING SHEAR OVER THIS AREA. THE COMPUTER MODELS MAINTAIN THE 
SYSTEM AS IT MOVES WEST BUT DOES NOT INDICATE DEVELOPMENT.

TROPICAL WAVE FROM 04N TO 12N ALONG 129W MOVING W 15-20 KT. 
SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 200 NM EAST OF 
THE WAVE AXIS. SOUTHERLY UPPER LEVEL FLOW IS CAUSING SHEARED 
CONDITIONS OVER THIS SYSTEM. THE COMPUTER MODELS DO NOT RESOLVE 
THIS FEATURE VERY WELL. DEVELOPMENT IS NOT FORECAST AS THE WAVE 
MOVES WEST.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...06N77W T0 
09N105W TO 10N120W TO 07N140W. SCATTERED MODERATE TO STRONG 
CONVECTION IS WITHIN 120 NM OF THE POINT 06N79W INCLUDING THE 
SOUTHERN PART OF THE GULF OF PANAMA. SCATTERED MODERATE WITH 
ISOLATED STRONG CONVECTION IS WITHIN A LARGE AREA 90 NM EITHER 
SIDE OF THE ITCZ AXIS WEST OF 120W.

...DISCUSSION...

A DEEP LAYER CYCLONIC CIRCULATION IS CENTERED NEAR 37N138W AND 
HAS BEEN NEARLY STATIONARY THE LAST 24 HOURS. IT IS EXPECTED TO 
CHANGE LITTLE AND ALSO MOVE LITTLE THROUGH THE NEXT COUPLE OF 
DAYS THEN BE PICKED UP AND ABSORBED BY WESTERLY FLOW. THE 
CIRCULATION IS FORECAST TO PULL THE SHARP TROUGH MENTIONED BELOW 
NORTHWARD AND INTO THE WESTERLIES NORTH OF THE AREA. DEEP LAYER 
MOISTURE ASSOCIATED WITH THE CYCLONIC CIRCULATION EXTENDS OVER 
THE AREA NORTH OF 25N WEST OF 128W. THE MIDDLE AND UPPER LEVELS 
ARE CLOUD FREE EXCEPT FOR BROKEN MIDDLE AND HIGH CLOUDS NORTH OF 
30N FROM 133W TO 137W. IN THE LOWER LEVELS MOSTLY OVERCAST 
STRATOCUMULUS IS OBSERVED. 

A SHARP MOSTLY UPPER TROUGH IS WEST OF A LINE THROUGH 32N122W TO 
18N120W AND EXTENDS WEST TO 130W. EXCEPT AS NOTED WITH THE ABOVE 
MENTIONED CYCLONIC CIRCULATION THE AREA WEST OF THE AXIS IS DRY 
AND CLOUD FREE IN THE MIDDLE AND UPPER LEVELS WITH OVERCAST 
STRATOCUMULUS NORTH OF 17N. THE TROUGH IS FORECAST TO BY PULLED 
NORTHWARD AND BE INCORPORATED INTO THE FLOW NORTH OF THE REGION 
IN THE NEXT SEVERAL DAYS. 

ANOTHER DEEP LAYER TROUGH EXTENDS ACROSS THE NORTHWEST GULF OF 
MEXICO ACROSS CENTRAL MEXICO AND OVER A PORTION OF THE PACIFIC 
OCEAN. THE TROUGH IS WITHIN THE AREA FROM SOUTH TEXAS TO NEAR 
20N118W TO 12N112W TO 12N107W TO 19N104W TO BEYOND 25N92W.
MOST OF THE TROUGH AREA IS DRY AND CLOUD FREE IN THE MIDDLE AND 
UPPER LEVELS. EAST OF THE TROUGH SCATTERED MODERATE TO STRONG  
CONVECTION OFFSHORE THE COAST OF MEXICO NORTH OF 12.5N FROM 98W 
TO 106W. THIS CONVECTION IS ALSO MENTIONED IN THE TROPICAL WAVE 
SECTION.

BETWEEN THE TWO TROUGHS MENTIONED ABOVE AND ALSO OVER NORTHERN 
MEXICO ANTICYCLONIC FLOW IS OBSERVED. THIS FLOW IS DIFFLUENT 
ALOFT OVER MAINLAND MEXICO WITH DEEP LAYER MOISTURE HOWEVER NOT 
A LOT OF CLOUDINESS IS OBSERVED ONLY PATCHES OF BROKEN HIGH 
CLOUDS NORTH OF 25N. THESE CLOUDS ARE DIMINISHING. 

EAST OF THE ABOVE MENTIONED SYSTEMS WEAK DEEP LAYER ANTICYCLONIC 
FLOW IS OBSERVED. THIS AREA HAS BECOME DRYER IN THE LAST 24 
HOURS WITH ONLY ISOLATED CONVECTION. OTHERWISE THIS AREA IS DRY 
AND CLOUD FREE EXCEPT FOR OVERCAST OCCASIONALLY BROKEN 
STRATOCUMULUS SOUTH OF THE ITCZ EAST OF 115W.

MODERATE SURFACE RIDGE IS NORTH OF 15N WEST OF 110W. REMAINDER 
OF THE SURFACE IS ANALYZED AS WEAK TROUGH.

GAP NE TO E WINDS OF 20 TO 25 KNOTS IN AND DOWNSTREAM OF GULF OF 
PAPAGAYO TO NEAR 94W ARE FORECAST TO CONTINUE THROUGH THE COUPLE 
OF DAYS.

LONG PERIOD SOUTHERLY SWELLS OF 8 FT ARE CROSSING THE EQUATOR 
THROUGH TROPICAL E PACIFIC AND REACHING COAST OF CENTRAL AMERICA 
AND MEXICO. SEAS OF 8 FT ARE CONFINED TO SOUTH OF 15N.

$$
LL