000
AXPZ20 KNHC 190352
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED AUG 19 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.

...TROPICAL WAVES...

TROPICAL WAVE FROM 07N101W TO 16N103W MOVE W AT 15 KT. ONLY 
ISOLATED MODERATE CONVECTION IS NEAR THE WAVE AXIS AND THE 
CONVECTION DOES NOT APPER TO BE ORGANIZED BY LOW LEVEL CYCLONIC 
FLOW.
 
TROPICAL WAVE FROM 08N TO 16N ALONG 115W MOVE W AT 15 KT. AN 
AREA OF SCATTERED MODERATE CONVECTION IS WITHIN 75 NM OF THE 
POINT 11N116.5W. A SLIGHT CYCLONIC ROTATION IS NOTED. EASTERLY 
SHEAR OVER THE SYSTEM MAKES ANY SIGNIFICANT ORGANIZATION OF WAVE 
UNLIKELY. THE COMPUTER MODELS FORECAST LITTLE MOTION OR CHANGE 
IN THIS SYSTEM FOR TWO DAYS THEN DEVELOP A LOW AND MOVE IT WEST.

TROPICAL WAVE FROM 07N TO 15N ALONG 126W MOVE W AT 15 KT. 
SCATTERED MODERATE CONVECTION IS WITHIN 100 NM EITHER SIDE OF 
THE AXIS. THERE APPEARS TO BE BROAD CYCLONIC TURNING IN THE 
VICINITY OF THE WAVE AXIS. THE ASSOCIATED CONVECTION IS BEING 
ENHANCED BY A TROUGH DROPOPING SOUTHWARD JUST WEST OF THE WAVE 
AXIS. COMPUTER MODELS FORECAST THIS SYSTEM TO DEVELOP SLOWLY AS 
THE SYSTEM MOVES WEST.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...06N77W TO 
08N105W TO 09N140W. SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION IS WITHIN 60 NM EITHER SIDE OF THE ITCZ AXIS FROM 88W 
TO 97W. SCATTERED MODERATE CONVECTION IS WITHIN 75 NM OF THE 
POINT 09N106.5W AND THE POINT 11N116.5W.

...DISCUSSION...

RIDGE IS NORTHWEST OF A LINE THROUGH 32N133W TO 20N140W. THE 
AREA IS DRY AND CLOUD FREE IN THE MIDDLE AND UPPER LEVELS WITH 
OVERCAST TO BROKEN STRATOCUMULUS IN THE LOWER LEVELS. THE 
FEATURE IS FORECAST TO DRIFT NORTHWEST AND WEAKEN BECOMING 
DIFFUSE THURSDAY.

DEEP LAYER TROUGH IS EAST OF THE RIDGE AND NORTHWEST OF A LINE 
THROUGH 32N120W TO THE ITCZ NEAR 128W. THIS AREA IS ALSO DRY AND 
CLOUD FREE IN THE MIDDLE AND UPPER LEVELS WITH MOSTLY OVERCAST 
STRATOCUMULUS NORTH OF 22N AND SCATTERED TO BROKEN STRATOCUMULUS 
SOUTH OF 22N IN THE LOWER LEVELS. THIS FEATURE IS FORECAST TO 
MOVE WEST REACHING 140W LATE THURSDAY. THIS TROUGH IS DEVELOPING 
SOUTHWARD AND CONVECTION IS SOMEWHAT ENHANCED IN THE ITCZ 
BECAUSE OF UPPER DIFFLUENCE ASSOCIATED WITH THE LEADING EDGE OF 
THE TROUGH.

EAST OF THE TROUGH TO 107W A RIDGE IS OBSERVED. THE SOUTHERLY 
FLOW IN THE RIDGE...WEST OF MEXICO N OF 21N AND WEST OF 113W 
SOUTH OF 21N...IS MOSTLY DRY AND CLOOUD FREE IN THE MIDDLE AND 
UPPER LEVELS EXCEPT FOR A NARROW BAND OF MOISTURE BETWEEN 120W 
AND THE TROUGH TO THE WEST. THE NORTHERLY FLOW IN THE RIDGE IS 
SOMEWHAT DIFFLUENT ALOFT WITH CONVECTION OVER MAINLAND MEXICO IN 
THE SIERRA OCCIDENTALS AND OVER THE OCEAN WIDESPREAD MULTI LAYER 
CLOUDINESS AND WIDELY SCATTERED MODERATE CONVECTION. THIS 
FEATURE IS FORECAST TO WEAKEN AND CONTRACT NORTHWARD IN THE NEXT 
COUPLE OF DAYS.

EAST OF THE ABOVE RIDGE TO ABOUTH 100W A NARROW TROUGH IS 
OBSERVED. THERE IS A NARROW BAND OF DRY CONDITION NEAR THE 
TROUGH AXIS BUT MOST OF THE TROUGH AREA IS MOIST IN THE MIDDLE 
AND UPPER ELVELS WITH WIDESPREAD MULTI LEVEL CLOUDINESS AND 
EMBEDDEDED AREAS OF CONVECTION.

EAST OF 100W BROAD ANTICYCLONIC FLOW IS OBSERVED WITH DIFFLUENT 
CONDITION ALOFT AND WIDESPREAD MULTI LEVEL CLOUDINESS. ENHANCED 
ITCZ CONVECTION IS NOTED IN THIS AREA.

WEAK TO MODERATE SURFACE RIDGE IS NORTH OF 17N WEST OF 115W. 
ELSEWHERE BROAD TROUGH IS ANALYZED AT THE SURFACE.

SOUTHERLY WINDS OF NEAR 20 KNOTS ACROSS THE EQUATOR WITH SW 
SWELLS OF NEAR 8 FT.

GAP WINDS EXPECTED TO INCREASE GULF OF PAPAGAYO WITHIN 24-36 HRS 
WITH SEAS LESS THAN 8 FT.  

$$
LL