000
AXPZ20 KNHC 202203
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED APR 20 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 
2145 UTC.

...ITCZ...

AXIS IS CENTERED ALONG 8N83W 6N96W 5N104W 8N115W 4N127W 3N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED IS WITHIN 
120 NM N OF THE AXIS BETWEEN 90W-96W...AND ALSO FROM 6N-10N 
BETWEEN 113W-120W. SCATTERED MODERATE CONVECTION IS WITHIN 180 
NM N OF THE AXIS BETWEEN 120W-130W.

...DISCUSSION...

ZONAL FLOW ALOFT GENERALLY DOMINATES THE DISCUSSION AREA N OF 
ABOUT 20N AS LARGE TROUGHS CONTINUE TO BYPASS THE REGION AS 
THEY MIGRATE FROM W TO E JUST TO THE N OF THE AREA. ONE NOTABLE
LONGWAVE TROUGH IS ALONG 129W...AND QUICKLY MOVING EWD TOWARDS 
THE U.S. W COAST. THIS TROUGH EXTENDED SW TO NW OF THE HAWAIIAN 
ISLAND CHAIN. S OF 20N...BROAD RIDGING CONTINUED ACROSS AND TO 
THE N OF ACTIVE ITCZ CONVECTION OCCURRING BETWEEN 88W AND 138W. 
THIS CONVECTION IS EXPECTED TO REMAIN ACTIVE DURING THE NEXT 24 
TO 48 HOURS NEAR THE ITCZ...AS SST'S REMAIN WARM AND LOW LEVEL 
FORCING PERSISTS...PARTICULARLY W OF 115W.

AT LOWER LEVELS...HIGH PRES AND ANTICYCLONIC FLOW DOMINATES THE 
AREA N OF 10N AND W OF 105W...CENTERED ON A 1022 MB HIGH LOCATED 
NEAR 27N129W WITH A RIDGE EXTENDING SE TO NEAR 13N105W. THE HIGH 
AND RIDGE ARE FORECAST TO DISSIPATE WITHIN THE NEXT 24 HOURS AS 
A COLD FRONT PASSES JUST TO THE N OF THE AREA. THIS FRONT WILL 
NOT BRING ANY SENSIBLE WEATHER CHANGES TO THE DISCUSSION WATERS 
OTHER THAN A BRIEF WIND SHIFT BEFORE HIGH PRES REBUILDS IN 
ACROSS THE AREA BEHIND THE FRONT. CURRENTLY THERE REMAINS A 
SMALL AREA OF 20 KT NE TRADE WINDS ON THE SOUTHERN PERIPHERY OF 
THE RIDGE FROM 4N TO 14N W OF 135W AND FROM 7N TO 13N BETWEEN
124W-135W AS SUGGEST BY A HIGH RESOLUTION ASCAT PASS FROM THIS
AFTERNOON. THIS AREA OF TRADES WILL CHANGE ONLY LITTLE DURING THE
NEXT 48 HOURS AS NEW HIGH PRES BUILDS FROM W TO E OVER THE NW 
PORTION OF THE AREA.

A TIGHT PRES OVER THE NE PORTION OF THE AREA BETWEEN THE RIDGE 
AND LOWER PRES OVER WESTERN U.S. AND NW MEXICO IS RESULTING IN 
20 NW WINDS WITHIN 120 NM OF THE BAJA CALIFORNIA COAST N OF 24N. 
THESE WINDS ARE FORECAST TO INCREASE TO 20-25 KT OVERNIGHT AND 
INTO THU MORNING AS THE PRES GRADIENT BETWEEN THE RE-BUILDING 
HIGH PRES BEHIND THE COLD FRONT AND LOWER PRES OVER MEXICO 
TIGHTENS.

THREE RATHER WEAK PERTURBATIONS ARE SUGGESTED IN SATELLITE 
IMAGERY ALONG THE ITCZ. A TROUGH IS ALONG 137W FROM 4N TO 9N 
...ANOTHER FROM 10N118W TO 6N120W...AND ANOTHER ONE FROM 10N93W
TO 5N96W. THE WEAK LOW TO MID CYCLONIC CIRCULATION EARLIER NOTED 
WITH THE THIRD TROUGH HAS BECOME LESS IDENTIFIABLE OVER RECENT 
HOURS. ALL OF THESE FEATURES ARE ENHANCING ITCZ CONVECTION AS 
DESCRIBED ABOVE.

A LOW TO MID LEVEL DEFORMATION ZONE REMAINS TO THE NW OF THE 
THIRD TROUGH MENTIONED ABOVE. IT IS COMBINING WITH THE MID LEVEL 
TROUGH EXTENDING W INTO CENTRAL MEXICO TO ENTRAIN A PLUME OF 
TROPICAL MOISTURE FROM NEAR 11N105W THROUGH THE GULF OF 
TEHUANTEPEC AND INTO SE MEXICO AND GUATEMALA. SCATTERED SHOWERS
AND TSTMS WITHIN 60 NM SE OF THE MOISTURE PLUME WILL CONTINUE TO
TRAIN NORTHEASTWARD TOWARDS THE GULF OF TEHUANTEPEC...AND INTO
INLAND MEXICO. THIS MOISTURE COMBINED WITH DAYTIME HEATING WILL
LIKELY ALLOW FOR ACTIVE CONVECTION TO CONTINUE INLAND OVER SE
MEXICO AND NORTHERN GUATEMALA THROUGH...WITH POSSIBLE
HEAVY RAINFALL THROUGH THE NEXT COUPLE OF DAYS.

VERY LONG PERIOD 19-21 SECOND CROSS-EQUATORIAL SW SWELL WILL 
PROPAGATE NE ACROSS THE EQUATORIAL WATERS DURING THE REMAINDER 
OF THE WEEK...REACHING COASTAL AREAS FROM COLOMBIA TO BAJA 
CALIFORNIA THU MORNING...AND INTO SOUTHERN CALIFORNIA BY FRI 
MORNING. WHILE DEEP WATER WAVE HEIGHTS WILL BE LESS THAN 8 FT AS 
THE SWELL PROPAGATES AWAY FROM THE EQUATOR...THIS HIGH ENERGY 
SWELL IS EXPECTED TO SLOWLY BUILD TO 3 TO 6 FT BY FRI AND WILL 
CREATE VERY HAZARDOUS SURF CONDITIONS ALONG EXPOSED COASTAL 
LOCATIONS...INCLUDING SIGNIFICANT RIP CURRENT HAZARDS LATE THU 
THROUGH SAT.

$$
AGUIRRE