000
AXPZ20 KNHC 180245
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT JUN 18 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0245 UTC.

...SPECIAL FEATURES...

A CIRCULATION CONTINUES TO BECOME SOMEWHAT BETTER DEFINED NEAR 
13N94W...APPROXIMATELY 240 NM S OF SALINA CRUZ MEXICO ON THE 
GULF OF TEHUANTEPEC. CONVECTION HAS DIMINISHED FURTHER THROUGH 
THE EVENING...WITH THE HEAVIEST CONVECTION STILL DISPLACED ABOUT 
180 NM W OF THE CENTER. SCATTEROMETER DATA FROM THIS MORNING 
INDICATED THAT WINDS WERE GENERALLY LESS THAN 20 KT...BUT A 
COUPLE OF MORE RECENT SHIP OBSERVATIONS SHOW 20 KT IN CONVERGENT 
BANDS AS MUCH AS 150 NM FROM THE CENTER. THE LOW PRES IS LOCATED 
ON THE SOUTHERN PERIPHERY OF A BROAD UPPER RIDGE CENTERED OVER N 
CENTRAL MEXICO. EASTERLY SHEAR ON THE S SIDE OF THE UPPER RIDGE 
APPEARS TO BE INHIBITING SIGNIFICANT CONVECTION SO FAR. THE 
RIDGE WILL WEAKEN THROUGH SUN AS A DEEP LAYER TROUGH DIGS INTO 
THE WESTERN UNITED STATES. GLOBAL MODELS SHOW THE LOW GRADUALLY 
DEEPENING OVER THE NEXT COUPLE OF DAYS...ALONG WITH A 
COMMENSURATE INCREASE IN SW FLOW S OF THE MONSOON TROUGH. THERE 
CONTINUES TO BE SOME DISCORD IN THE MID RANGE GUIDANCE...WITH 
THE GFS STILL SHOWING THE LOW MOVING INTO THE COAST NEAR 
MANZANILLO. REGARDLESS OF THE ULTIMATE TRACK OF THIS 
LOW...CONVECTION ALONG THE N SIDE OF THE LOW WILL IMPACT THE 
COASTLINE ALONG GUATEMALA AND SOUTHERN MEXICO OVER THE NEXT 
COUPLE OF DAYS.

...ITCZ/MONSOON TROUGH...

MONSOON TROUGH EXTENDS FROM 12N87W TO LOW PRES NEAR 13N94W 1007 
MB TO 11N103W TO 11N120W TO 08N125W. THE ITCZ EXTENDS FROM 
08N125W TO 06N135W TO BEYOND 06N140W. SCATTERED MODERATE 
ISOLATED STRONG WITHIN 180 NM N OF AXIS BETWEEN 90W AND 100W. 
SCATTERED MODERATE WITHIN 120 NM S OF AXIS BETWEEN 98W AND 105W. 
SCATTERED MODERATE WITHIN 30 NM EITHER SIDE OF LINE BETWEEN 132W 
AND 138W. 

...DISCUSSION...
THE DEVELOPMENT OF THE LOW PRES NEAR 12N93W WILL CONTINUE TO BE 
THE MAIN WEATHER ISSUE E OF 110W. SW WINDS WILL INCREASE TO 20 
TO 30 KT S OF MONSOON TROUGH MAINLY IN A BROAD SWATH WITHIN 500 
NM TO THE SE OF THE LOW...AS THE LOW DEEPENS THROUGH 48 HOURS. 
SEAS WILL INCREASE ACCORDINGLY TO 11 FT IN THIS AREA. FURTHER TO 
THE SE...CONVERGENCE OF MODERATE SW WINDS WILL BRING CLUSTERS OF 
CONVECTION THROUGH PANAMA OVER THE NEXT 24 TO 48 HOURS. 

FURTHER WEST...AN UPPER TROUGH IS SITUATED NEAR 23N137W. DESPITE 
BRINGING DRY AND SUBSIDENT AIR ACROSS THE REGION W OF 
120W...DIVERGENCE ALOFT ON THE SE SIDE OF THE UPPER TROUGH IS 
ENHANCING MODEST CONVECTION W OF 135W ALONG THE ITCZ.

1033 MB HIGH PRES CENTERED NEAR 37N145W WILL SHIFT E TO 135W 
THROUGH SUN...RESULTING IN FRESH NW FLOW ALONG THE COAST OF BAJA 
SAT AND SUN.

$$
CHRISTENSEN