000
AXPZ20 KNHC 292204
TWDEP 

TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
2205 UTC WED MAY 29 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...SPECIAL FEATURE...

EYE OF HURRICANE BARBARA MADE LANDFALL ON THE COAST OF MEXICO 
NEAR 16.0N 94.0W ABOUT 20 MI...35 KM W OF TONALA MEXICO... OR  
ABOUT 80 MI...130 KM E OF SALINA CRUZ MEXICOAT 1950 UTC. 

AT 2100 UTC...HURRICANE BARBARA NEAR 16.2N 94.0W OR ABOUT 80 
MI...130 KM E OF SALINA CRUZ MEXICO 990 MB MOVING NNE OR 030 DEG 
AT 8 KT. MAXIMUM SUSTAINED WINDS 65 KT GUSTS 80 KT. A HURRICANE 
WARNING IS IN EFFECT FOR...PUERTO ANGEL TO BARRA DE TONALA 
MEXICO. A TROPICAL STORM WARNING IS IN EFFECT FOR...BARRA DE 
TONALA TO BOCA DE PIJIJIAPAN MEXICO. BARBARA WILL CONTINUE TO 
MOVE NNE THROUGHOUT THE NIGHT...BRINGING BANDS OF TORRENTIAL 
SHOWERS AND THUNDERSTORMS ACROSS CHIAPAS...LEADING TO FLASH 
FLOODING AND HIGH POTENTIAL FOR MUDSLIDES. TROPICAL STORM FORCE 
SOUTHERLY WINDS WILL PUSH LARGE WAVES AND A MODEST STORM SURGE 
ALONG THE COAST. 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 HURRICANE BARBARA FROM 17N104W TO A 
1008 MB LOW PRES NEAR 12N113W TO 08N120W 07N132W...WHERE IT 
TRANSITIONS TO ITCZ...CONTINUING ON TO BEYOND 06N140W.  
SCATTERED CLUSTERS OF MODERATE ISOLATED STRONG CONVECTION IS N 
OF 05N BETWEEN 78W AND 90W. HURRICANE BARBARA NEAR 16.2N 
94.0W...NUMEROUS STRONG CONVECTION IS WITHIN 60 NM OF CENTER. 
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ELSEWHERE FROM 
11N TO 18N BETWEEN 91W AND 100W. LOW PRES NEAR 13N113W 1008 
MB...SCATTERED MODERATE CONVECTION IS WITHIN 120 NM W 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. 

MONSOONAL FLOW DOMINATES THE TROPICS E OF 120W...AND IS FORECAST 
TO LIFT NORTHWARD DURING THE NEXT FEW DAYS...WITH BARBARA 
EMBEDDED WITHIN...AND ALONG W COASTAL PORTIONS OF CENTRAL 
AMERICA AND SOUTHERN MEXICO...AND IS EXPECTED TO PRODUCE VERY 
MOIST AND UNSTABLE CONDITIONS DURING THIS PERIOD. NEAR THE W END 
OF THE MONSOON TROUGH...A SECOND LOW PRES CENTER IS ALSO 
EMBEDDED WITHIN THE MONSOON TROUGH NEAR 13N113W. CONVECTION HAS 
BEEN FLARING ON AND OFF DURING THE PAST DAY OR SO WITH THIS 
FEATURE. DRIER MIDDLE LEVEL AIR AND MODEST UPPER LEVEL 
CONVERGENCE PREVAILED THIS MORNING JUST TO THE N AND NE OF THIS 
LOW AND IS AIDING IN LIMITING CONVECTION. THIS LOW IS FORECAST 
TO SHIFT NE OVER THE NEXT FEW DAYS AND GRADUALLY WEAKEN BY FRI. 
HOWEVER THERE REMAINS A MEDIUM CHANCE FOR THIS LOW TO BECOME 
BETTER ORGANIZED AND DEVELOP INTO A TROPICAL CYCLONE DURING THE 
NEXT 48 HOURS. 
 
AT THE SURFACE...A 1026 MB HIGH LOCATED NEAR 31N144W 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 28N AND E OF 123W 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