000
AXPZ20 KNHC 190352
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU MAY 19 2011

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0130 UTC.
 
...ITCZ...
AXIS ALONG 10N84W TO 10N91W TO 06N102W TO 05N118W TO 06N132W TO 
03N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED 
FROM 04N TO 11N BETWEEN 82W AND 108W. SCATTERED TO LOCALLY 
MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 150 NM OF AXIS 
W OF 125W.

...DISCUSSION...
A REX BLOCK PATTERN HAS EVOLVED DURING THE PAST 24 HOURS ACROSS 
THE E CENTRAL PACIFIC...CENTERED ON AN ANTICYCLONE-CYCLONE 
COUPLET ALONG 138-140W. ASSOCIATED DOWNSTREAM CYCLONE WAS 
CENTERED OVER THE WRN U.S. AND EXTENDED S-SE TO SW ARIZONA. THE 
UPPER CYCLONE CENTERED NEAR 21N140W ANCHORED A NEARLY STATIONARY 
MID TO UPPER LEVEL TROUGH THAT EXTENDED NE THEN E ACROSS CENTRAL 
BAJA CALIFORNIA. SE OF THESE FEATURES REMAINED A BROAD UPPER 
RIDGE GENERALLY N OF 05N...WITH ANTICYCLONIC FLOW ALOFT SPANNING 
FROM 73W TO 130W. PULSING DEEP CONVECTION NEAR THE ITCZ BETWEEN 
90W AND 110W DURING THE PAST FEW DAYS COUPLED WITH SHORTWAVE 
ENERGY LIFTING OVER THIS UPPER RIDGE HAVE AIDED IN THE RIDGE 
BUILDING N AND NW THE PAST 24 HOURS. WATER VAPOR IMAGERY SHOWED 
A SMALL UPPER ANTICYCLONE NEAR 04N108W...LOCATED IN THE SW 
PORTION OF THIS BROAD ANTICYCLONIC FLOW. OTHERWISE...NO DISTINCT 
ANTICYCLONIC CENTERS WERE NOTED IN WATER VAPOR IMAGERY...WITH 
THE UPPER RIDGE BEING MAINTAINED BY INDUCED DIVERGENCE CREATED 
FROM INTERMITTENT LARGE CLUSTERS OF DEEP CONVECTION ACROSS THIS 
AREA THE PAST WEEK. GLOBAL MODELS SHOW A SHARP LONGWAVE 
TROUGH APPROACHING THE REGION FROM THE W DURING THE NEXT FEW 
DAYS AND ACTING TO BREAK DOWN THE REX BLOCK OVER THE UPCOMING 
WEEKEND....ALLOWING A BROAD BLOCKING UPPER RIDGE TO REALIGN 
ALONG 108W.

A WEAKENING SURFACE RIDGE CONTINUES ACROSS N AND NW PORTIONS OF 
AREA THIS EVENING...CENTERED ON 1023 MB HIGH NEAR 34N136W AND 
EXTENDS SE...BRIDGING ACROSS A DISSIPATING COLD FRONT THAT 
EXTENDS FROM FAR NRN BAJA CALIFORNIA TO 28N135W...WITH RIDGING 
CONTINUING TO NEAR 19N111W. THE FRONT WILL MOVE E AND INLAND 
TONIGHT ALLOWING THE RIDGE TO BUILD E AND SE AND BRING FRESH NW 
BREEZE ALONG W COAST OF BAJA CALIFORNIA. EPAC MONSOONAL FLOW 
PREVAILS E OF 110W...WITH S TO SW WINDS DEPICTED BY AFTERNOON 
SCATTEROMETER PASSES S OF THE DEFINED ITCZ FROM COLOMBIA TO 
120W. ABUNDANT TROPICAL MOISTURE ACROSS THIS REGION FROM 03N TO 
11N AND E OF 110W IS EXPECTED TO CONTINUE TO PULSE IN CLUSTERS 
OF DEEP CONVECTION DURING THE NEXT 24 HOURS.

LARGE VERY LONG PERIOD CROSS EQUATORIAL SW SWELLS CONTINUE TO 
PROPAGATE THROUGH THE AREA WATERS AND BEYOND...HAVING BEGUN TO 
REACH 35N LATE THIS AFTERNOON PER COASTAL BUOY DATA...AND WILL 
PEAK THIS EVENING AND TONIGHT ACROSS THE COASTAL WATERS OF 
CENTRAL AMERICA AND MEXICO TO PRODUCE VERY LARGE AND POWERFUL 
SURF...WITH THE POTENTIAL FOR COASTAL FLOODING ALONG THE 
COASTLINES. OFFSHORE WAVE HEIGHTS WILL PEAK AT 10 TO 11 FT EARLY 
TONIGHT BEFORE THE SW SWELL SUBSIDES STEADILY THU THROUGH FRI. 

$$
STRIPLING