000
AXPZ20 KNHC 201514
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON JUN 20 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.

...SPECIAL FEATURES...
TROPICAL STORM BEATRIZ IS CENTERED NEAR 16.3N 102.9W AT 20/1500 
UTC OR ABOUT 180 NM S-SE OF MANZANILLO MEXICO MOVING NW OR 320 
DEG AT 08 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 995 MB. 
MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 60 KT. BASED 
ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1400 
UTC. NUMEROUS MODERATE SCATTERED STRONG CONVECTION LIES WITHIN 
210 NM N AND WITHIN 180 NM S SEMICIRCLES. BEATRIZ IS FORECAST TO 
BECOME A HURRICANE TONIGHT AS IT CONTINUES ON A NW TRACK 
PARALLELING THE MEXICAN COAST. SEE THE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC 
FOR MORE DETAILS.
  
...ITCZ/MONSOON TROUGH...
MONSOON TROUGH FROM 15N93W TO SE OF TROPICAL STORM BEATRIZ AT 
16N103W THEN CONTINUES FROM 12N110W TO 07N126W. ITCZ EXTENDS 
FROM 07N126W TO BEYOND 06N140W. ASIDE FROM CONVECTION NOTED WITH 
TROPICAL STORM BEATRIZ...SCATTERED MODERATE ISOLATED STRONG 
CONVECTION LIES WITHIN 90 NM EITHER SIDE OF THE MONSOON TROUGH 
BETWEEN 94W TO 115W. SCATTERED MODERATE CONVECTION LIES WITHIN 
60 NM EITHER SIDE OF THE ITCZ W OF 136W.

...DISCUSSION...
THE SUBTROPICAL HIGH NORTH OF THE FORECAST AREA IS BEING 
COMPROMISED BY A COLD FRONT APPROACHING IT FROM THE NW. TRADE 
WINDS HAVE DIMINISHED DUE TO THE WEAKENED SUBTROPICAL HIGH. THE 
SUBTROPICAL HIGH WILL GRADUALLY BE REPLACED BY HIGH PRES TO THE 
NW OF THE AFOREMENTIONED COLD FRONT...BUT TRADES ARE NOT 
EXPECTED TO RETURN BEFORE WED MORNING. THE SUBTROPICAL RIDGE 
AXIS EXTENDS INTO THE FORECAST AREA FROM 31N132W TO 15N110W. THE 
PRES GRADIENT IS TIGHTEST OVER FORECAST WATERS ON THE NE SIDE OF 
THE RIDGE AXIS BETWEEN IT AND THE PERSISTENT TROUGHING OVER THE 
SW UNITED STATES AND THE GULF OF CALIFORNIA. THE FRESH NW TO N 
WINDS THAT LIE JUST W OF BAJA CALIFORNIA N OF 25N ARE EXPECTED 
TO CONTINUE FOR THE NEXT FEW DAYS. FAIR WEATHER AND STABLE 
CONDITIONS CAN BE FOUND OVER MUCH OF THE AREA DOMINATED BY THE 
SUBTROPICAL HIGH N OF 10N W OF 115W.

DIFFLUENCE ALOFT BETWEEN THE SOUTHWESTERLY FLOW ON THE S SIDE OF 
AN UPPER LOW NEAR 29N142W AND THE EASTERN EDGE OF AN 
NORTHWESTERLY JET THAT EXTENDS INTO THE AREA S OF 12N W OF 
135W IS ENHANCING CONVECTION ALONG THE ITCZ OVER FAR W WATERS. 
THE UPPER LOW IS FORECAST TO RETROGRADE NW...CARRYING THE AREA 
OF BEST DIFFLUENCE AWAY FROM THE LOW LEVEL CONVERGENCE OF THE 
ITCZ AND OUT OF THE FORECAST AREA.

AN UPPER ANTICYCLONE NEAR 23N115W EXTENDS A RIDGE EASTWARD ALONG 
23N INTO CENTRAL MEXICO. UPPER DIFFLUENCE S OF THIS RIDGE IS 
ENHANCING THE CONVECTION ASSOCIATED WITH TROPICAL STORM BEATRIZ 
AND THE CONVECTION ALONG THE MONSOON TROUGH PREVIOUSLY 
MENTIONED. CONVECTIVE BLOW OFF E OF 100W IS ADVECTING 
SOUTHWESTWARD UNDER STRONG UPPER LEVEL NORTHEASTERLY FLOW. THESE 
STRONG WINDS ALOFT ARE INHIBITING CONVECTION E OF 90W. 

STRONG LOW LEVEL SW WINDS CONTINUE S OF THE MONSOON TROUGH E OF 
120W TO THE COAST OF CENTRAL AMERICA JUST W OF THE GULF OF 
TEHUANTEPEC. CROSS EQUATORIAL SW SWELLS ARE CURRENTLY MOVING IN 
THE WATERS N OF THE EQUATOR BETWEEN 81W AND 110W. SEAS TO 8 FT 
ARE EXPECTED TO REACH THE COAST OF CENTRAL AMERICA TUE.

$$
SCHAUER