000
AXPZ20 KNHC 111018
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED JUN 10 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.

...SPECIAL FEATURE...
A LOW PRESSURE SYSTEM WAS ESTIMATED NEAR 12N118.5W...MOVING WNW 
NEAR 10 KT. A CENTRAL CLUSTER OF DEEP CONVECTION HAS GENERALLY 
PERSISTED WITH THE CORE OF THE LOW TO MID LEVEL CIRCULATION OF 
THIS LOW OVERNIGHT...BUT HAS BECOME SOMEWHAT ELONGATED AND 
CONCENTRATED ACROSS THE W AND NW PORTIONS OF THE CIRCULATION IN 
THE PAST COUPLE OF HOURS. THUS IT DOES NOT YET APPEAR THAT THIS 
SYSTEM IS GAINING BETTER ORGANIZATION. THIS LOW REMAINS EMBEDDED 
IN THE NORTHEASTERN END OF AN ELONGATED TROUGH...OR SEGMENT OF 
THE ITCZ...AND WILL LIKELY BEGIN TO SEPARATE FROM THE ITCZ IN 
THE NEXT 24-36 HOURS. SCATTEROMETER PASSES ACROSS THIS SYSTEM 
OVERNIGHT INDICATED 20-25 KT WINDS IN ALL BUT THE NE 
QUADRANT...AND ALSO SUGGEST THAT THE LOW LEVEL CENTER MAY BE ON 
THE EASTERN EDGE OF THE DEEP CONVECTION...AND A BIT TO THE NE OF 
OUR RECENT CENTER ESTIMATES. MICROWAVE PASSES OVER THIS SYSTEM 
OVERNIGHT SHOWED VERY SHORT CLOUD BANDS IN THE N AND NW 
QUADRANTS WHICH CONTINUE TO PULSE WITH CONVECTION. THIS SYSTEM 
LIES IN THE FAR WRN PERIPHERY OF AN UPPER ANTICYLONE CENTERED 
ALONG THE CENTRAL W COAST OF MEXICO...AND IN AN AREA OF GOOD 
DIFFLUENCE ALOFT...YIELDING SCATTERED MODERATE TO STRONG 
CONVECTION WITHIN 150 NM OF THE W AND NW SEMICIRCLES. SATELLITE 
TRENDS AND COMPUTER MODEL GUIDANCE SUGGEST THAT THERE IS A 
MEDIUM CHANCE...30 TO 50 PERCENT...OF THIS SYSTEM BECOMING A 
TROPICAL CYCLONE DURING THE NEXT 48 HOURS...AS IT MOVES 
NORTHWESTERLY. 

...TROPICAL WAVES...
THE SOUTHERN PORTION OF A TROPICAL WAVE THAT HAS BECOME 
STRETCHED AND SHEARED FROM THE NORTHERN PORTION...CURRENTLY  
ACROSS THE WRN CARIBBEAN...WAS MOVING SLOWLY ACROSS THE 
EPAC...AND WAS SUGGESTED S OF 13N BETWEEN 97W AND 100W.

...ITCZ...
AXIS WAS ALONG 09N79W TO 08N81W TO 09.5N86W TO 10N97W TO 07N106W 
TO LOW 12N118.5W TO 08N126W TO 06N140W. SCATTERED MODERATE TO 
STRONG CONVECTION WAS WITHIN 180 NM S OF AXIS BETWEEN 79W AND 
95W. SCATTERED MODERATE TO STRONG CONVECTION WAS WITHIN 120 NM 
OF AXIS BETWEEN 96W AND 111W...AND WITHIN 90 NM OF AXIS BETWEEN 
121W AND 129W. 
    
...DISCUSSION...

DIFFLUENCE ALOFT ON THE S SIDE OF THE UPPER HIGH OFF OF MEXICO 
CONTINUES TO ENHANCE CONVECTION ALONG THE ITCZ...AND SUSTAIN 
DIURNAL CONVECTION FROM YESTERDAY AFTERNOON THAT US PERSISTING 
OVER THE WARM WATERS WITHIN 120 NM OF THE COAST OF SRN MEXICO 
AND MUCH OF CENTRAL AMERICA. NOCTURNAL DRAINAGE FLOW WOULD 
APPEAR TO BE THE LOW LEVEL FOCUSING MECHANISM FOR THIS SUSTAINED 
CONVECTION. 

CONDITIONS ARE OTHERWISE QUIET ACROSS THE SUBTROPICS WITH 
ABUNDANT DRY AIR IN THE MID AND UPPER LEVELS ON EITHER SIDE OF 
AN UPPER TROUGH RESIDING ACROSS NW PORTIONS OF THE AREA. WINDS 
ARE LIGHT ACROSS THE REGION...EXCEPT NEAR THE BAJA COAST WHERE 
BROAD TROUGHING OVER MEXICO AND TERRAIN VARIATIONS HAVE 
GENERATED NW 20 KT WINDS...AND SW TO W WINDS NEAR 20 KT IN THE 
NRN GULF OF CALIFORNIA DURING THE LATE EVENING AND OVERNIGHT. 
WINDS ARE EXPECTED TO REMAIN SIMILAR OVER THE NEXT COUPLE OF 
DAYS AS THE PRESSURE PATTERN HOLDS.

VERY LONG PERIOD S TO SW SWELL EMANATING FROM A STRONG CYCLONE 
IN THE SOUTHERN HEMISPHERE HAS BEGUN TO AFFECT THE COASTS OF 
CENTRAL AMERICA AND MEXICO OVERNIGHT...AND WILL BUILD DURING THE 
NEXT 48 HOURS...AND IS EXPECTED TO PEAK IN SIZE ON SAT AND 
SUN...PRODUCING LARGE AND DANGEROUS BREAKING SURF ALONG THE 
COASTS FROM BAJA CALIFORNIA TO COLOMBIA. LONG PERIOD SWELL OF 2 
TO 2.5 METERS WILL REACH THE COASTLINES FROM SRN MEXICO TO 
PANAMA AT 15-16 SECONDS. SELECT DEEP WATER BREAKS AND BEACHES 
ACROSS THIS AREA MAY SEE BREAKING WAVES APPROACHING 20 FEET 
DURING THE WEEKEND.
 
$$
STRIPLING