000
AXPZ20 KNHC 172213
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE MAY 17 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.
 
...ITCZ...
AXIS ALONG 06N122W TO 03N140W.  NO SIGNIFICANT CONVECTION.

MONSOONAL TROUGH AXIS IDENTIFIED FROM 17N103W TO 11N110W TO 
06N122W. NUMEROUS MODERATE TO STRONG CONVECTION NOTED N OF 08N E 
OF AXIS TO 93W. SCATTERED TO LOCALLY NUMEROUS MODERATE ISOLATED 
STRONG CONVECTION NOTED ELSEWHERE FROM 04N TO 08N BETWEEN 80W 
AND 120W. 

...DISCUSSION...
SHARP DEEP LAYERED NEGATIVE TILT TROUGH ACROSS WRN N AMERICA 
EXTENDED SE INTO THE DESERT SW OF THE U.S. AND WITH BASE OF 
TROUGH TO 28N E OF 128W. TROUGH HAS MERGED ACROSS DESERT SW OF 
U.S. WITH A LINGERING MIDDLE TO UPPER LEVEL TROUGH EXTENDING 
W-SW ACROSS CENTRAL BAJA CALIFORNIA NEAR 28N114W TO A MID TO 
UPPER LEVEL CYCLONE E OF THE BIG ISLAND OF HAWAII NEAR 20N145W. 
MID TO UPPER CONVERGENCE AND SUBSIDENCE OCCURRING WITHIN THIS 
NARROW TROUGH. A BROAD UPPER RIDGE GENERALLY PREVAILS TO THE SE 
OF THESE FEATURES ACROSS THE REMAINDER OF THE AREA...WITH MEAN 
RIDGE AXIS EXTENDING FROM 20N TO 30N ACROSS MEXICO ALONG 
102W...AND NE TO E FLOW S OF THE RIDGE GENERALLY S OF 06N. 

AT LOWER LEVELS...A LARGE SURFACE RIDGE OVER THE E CENTRAL 
PACIFIC WAS CENTERED ON A 1024 MB HIGH NEAR 28N144W WITH RIDGE 
EXTENDING SE TO NEAR 20N115W. A MODEST PRESSURE GRADIENT OFF THE 
W COAST OF BAJA CALIFORNIA WAS PRODUCING A ZONE OF 20 KT NW TO N 
WINDS AND MIXED SEAS NEAR 8 FT FROM 21N TO 29N E OF 116W. SE OF 
THE RIDGE...MONSOONAL FLOW HAS BECOME DOMINANT ACROSS ERN 
TROPICAL PACIFIC E 115W...WITH S TO SW SURFACE WINDS GENERALLY S 
OF 07N CONVERGING WITH WLY SURFACE WINDS BETWEEN 07N AND 11N. 
ABUNDANT TROPICAL MOISTURE CONVERGING TO THE E AND SE OF THE 
MONSOONAL TROUGH AND COASTAL CENTRAL AMERICA AND MEXICO E OF 
100W HAS ERUPTED INTO SCATTERED TO NUMEROUS MODERATE TO DEEP 
CONVECTION DURING THE PAST 24 HOURS...WITH MOST ACTIVE 
CONVECTION RECENTLY OCCURRING FROM THE GULF OF TEHUANTEPEC W OF 
100W AND S TO 08N. THIS DEEP CONVECTION HAS BEEN SHIFTING SW 
DURING THE PAST FEW HOURS WITH GLOBAL MODEL GUIDANCE SUGGESTING 
THIS TREND SHOULD CONTINUE THROUGH THE EVENING HOURS. 

LARGE VERY LONG PERIOD SOUTHERN HEMI SWELL CONTINUES TO 
PROPAGATE ACROSS THE TROPICAL EPAC AND MOVE INTO THE SUB TROPICS 
N OF 20N THIS AFTERNOON. GLOBAL WAVE MODEL GUIDANCE INDICATES 
THESE SLY SWELLS CROSSING 30N THIS EVENING...WHILE WAVE HEIGHTS 
OF 8 TO 11 FT PREVAIL ACROSS THE TROPICAL EPAC S OF 20N AND E OF 
130W THROUGH THE NEXT 36 HOURS BEFORE DIMINISHING. 

$$
STRIPLING