000
AXPZ20 KNHC 300257
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
0405 UTC THU MAY 30 2013

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 
0200 UTC.

...SPECIAL FEATURE...

AT 0300 UTC...TROPICAL STORM BARBARA IS NEAR 17.1N 93.8W OR 
ABOUT 50 MI...85 KM WNW OF TUXTLA GUTIERREZ MEXICO...OR ABOUT 85 
MI...135 KM SSE OF COATZACOALCOS MEXICO MOVING NNE OR 020 DEG AT 
8 KT. MINIMUM CENTRAL PRESSURE IS 995 MB. MAXIMUM SUSTAINED 
WINDS ARE 45 KT GUSTS 55 KT. A TROPICAL STORM WARNING IS IN 
EFFECT FOR FROM SALINA CRUZ TO BOCA DE PIJIJIAPAN MEXICO. 
BARBARA WILL CONTINUE TO MOVE NORTHWARD THROUGHOUT THE 
NIGHT...BRINGING BANDS OF TORRENTIAL SHOWERS AND THUNDERSTORMS 
ACROSS CHIAPAS...LEADING TO FLASH FLOODING AND HIGH POTENTIAL 
FOR MUDSLIDES. SEE THE LATEST NHC FORECAST/ ADVISORY UNDER 
AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC...OR THE LATEST PUBLIC 
ADVISORY UNDER AWIPS/WMO HEADERS MIATCPEP2/WTPZ32 KNHC...FOR 
MORE DETAILS. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

MONSOON TROUGH EXTENDS W OF TROPICAL STORM BARBARA FROM 16N108W 
TO A 1006 MB LOW PRES NEAR 13N112W TO 08N120W TO 07N131W...WHERE 
IT TRANSITIONS TO ITCZ...CONTINUING ON TO BEYOND 07N140W. 
CLUSTERS OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION N 
OF 05N BETWEEN 80W AND 90W. TROPICAL STORM BARBARA NEAR 16.7N 
93.9W...SCATTERED MODERATE TO ISOLATED STRONG CONVECTION FROM 
11N TO 19N BETWEEN 92W AND 97W. LOW PRES NEAR 13N112W 1006 
MB...SCATTERED MODERATE CONVECTION WITHIN 120 NM OF CENTER.
 
...DISCUSSION...

ALOFT...AN UPPER LEVEL TROUGH ANCHORED ACROSS THE PACIFIC NW 
EXTENDS S-SE INTO NW MEXICO...THEN SW AS AN ELONGATING NARROW 
MIDDLE TO UPPER TROUGH...EXTENDING ACROSS THE S END OF BAJA 
CALIFORNIA TO NEAR 18N128W...WHERE IT IS DAMMING AGAINST THE 
TROPICAL RIDGE PREVAILING S OF 22N AND E OF 120W. TO THE W AND 
BROAD UPPER RIDGE DOMINATES W PORTIONS...ANCHORED ON AN UPPER 
ANTICYCLONE NEAR 16N137W EXTENDING A NARROW RIDGE N-NE TO NEAR 
24N133W...THEN BROADENS NORTHWARD TO 40N BEHIND THE W COAST 
UPPER TROUGH. 

W OF BARARA...A 1006 MB LOW CENTER IS EMBEDDED WITHIN THE 
MONSOON TROUGH NEAR 13N112W. CONVECTION HAS BEEN PREVAILING NEAR 
THE LOW OVER THE PAST 24 HOURS. A LARGE AREA OF SUBSIDENCE IS N 
AND W OF THE LOW...HOWEVER THE LOW IS MOVING ENE AND IS 
REMAINING UNDER A MOIST UPPER LEVEL ENVIRONMENT. THIS LOW HAS A 
MEDIUM CHANCE FOR BETTER ORGANIZATION AND DEVELOPMENT INTO A 
TROPICAL CYCLONE DURING THE NEXT 48 HOURS. 
 
AT THE SURFACE...A 1026 MB HIGH LOCATED NEAR 32N142W EXTENDS A 
RIDGE SEWD ACROSS THE FORECAST WATERS TO NEAR 20N120W. 
SCATTEROMETER DATA PROVIDED OBSERVATIONS OF MODERATE TO FRESH 
TRADE WINDS BETWEEN THE SRN PERIPHERY OF THE RIDGE AND THE 
ITCZ...COVERING THE AREA FROM 10N TO 15N W OF 135W. DUE TO A 
TIGHT PRES GRADIENT BETWEEN THE RIDGE AND LOWER PRES OVER NW 
MEXICO...NW TO N WINDS HAVE INCREASED TO 20-25 KT OVER THE NE 
PART OF THE FORECAST REGION N OF ABOUT 27N AND E OF 124W WITH 
SEAS THERE IN THE 8-10 FT RANGE. EXPECT THESE MARINE CONDITIONS 
TO PERSIST OVER THESE WATER FOR THE NEXT 48 HOURS.

LONG PERIOD CROSS EQUATORIAL SW SWELLS AT 14-16 SECONDS DOMINATE 
MOST OF THE FORECAST WATERS E OF 115W. THESE SWELLS ARE MERGING 
WITH NW TO N SWELLS THAT COVER THE REMAINDER OF THE FORECAST 
WATERS. SWELLS IMPACTING THE NE PORTION OF THE AREA WILL 
GRADUALLY SUBSIDE OVER THE NEXT COUPLE OF DAYS. 
 
$$ 
FORMOSA