000 AXPZ20 KNHC 201547 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC WED APR 20 2011 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1530 UTC. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ANALYZED FROM 06N77W TO 06N94W TO 05N101W TO 07.5N118W TO 03N126W TO 05N135W TO 03N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 120 NM N OF AXIS E OF 90W. SCATTERED MODERATE TO STRONG CONVECTION WAS ALSO NOTED WITHIN 90 NM EITHER SIDE OF AXIS FROM 95W TO 116W. ...DISCUSSION... ZONAL FLOW ALOFT GENERALLY DOMINATES THE DISCUSSION AREA ALOFT TODAY N OF 20N. A LONGWAVE TROUGH N OF THE AREA ALONG 132W WAS MOVING EWD TOWARD THE W COAST OF N AMERICA...AND EXTENDED SW TO NW OF THE HAWAIIAN ISLAND CHAIN. THE W END OF MID TO UPPER LEVEL TROUGH EXTENDED WWD ACROSS THE GULF OF MEXICO TO CENTRAL MEXICO AND WAS BEING NUDGED SE BY AN UPSTREAM RIDGE MOVING ACROSS THE DESERT SW OF THE U.S. AND N MEXICO. 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 SKIRTS BY TO THE N. 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 05N TO 13N W OF 135W. MODEL GUIDANCE INDICATES LITTLE CHANGE IN THIS AREA OF TRADES DURING THE NEXT COUPLE OF DAYS UNTIL THIS NEW RIDGE BUILDS INTO THE REGION OVER THE WEEKEND AND EXPANDS THE TRADES NWD BY SUN. LAST NIGHTS 0424 UTC EXPERIMENTAL ASCAT 25 KM COASTAL WINDS SHOWED AN AREA OF 20 KT NW WINDS N OF 24N WITHIN 120 NM W OF THE BAJA CALIFORNIA PENINSULA. WINDS ARE FORECAST TO INCREASE TO 25 KT TONIGHT THROUGH FRI MORNING AS THE PRES GRADIENT BETWEEN THE RE-BUILDING HIGH PRES BEHIND THE COLD FRONT AND LOWER PRES OVER MEXICO TIGHTENS. THREE UNDULATIONS OR PERTURBATIONS ARE SUGGESTED IN SATELLITE IMAGERY ALONG THE ITCZ. A TROUGH WAS ALONG 135W BETWEEN 02N AND 10N WITH SCATTERED MODERATE TO STRONG CONVECTION OCCURRING WITHIN 120 NM W AND 360 NM E OF TROUGH. A SECOND TROUGH WAS ALONG 120W BETWEEN 04N AND 12N WITH SCATTERED TO NUMEROUS MODERATE TO STRONG CONVECTION OCCURRING WITHIN 210 NM W AND 320 NM E OF AXIS. A THIRD TROUGH WAS ANALYZED ALONG 96W S OF 10N. SCATTERED MODERATE TO STRONG CONVECTION WAS OCCURRING WITHIN 180 NM E OF TROUGH. THIS THIRD THROUGH IS A PERSISTENT LOW TO MIDDLE LEVEL CYCLONIC CIRCULATION THAT WAS BEEN DRIFTING W ACROSS THIS AREA FOR THE PAST SEVERAL DAYS...AND IS EXPECTED TO CONTINUE TO DRIFT W AND GRADUALLY WEAKEN OVER THE WEEKEND. A WEAK SURFACE LOW MAY BE EMBEDDED WITHIN THIS CIRCULATION. A LOW TO MID LEVEL DEFORMATION ZONE EXISTS TO THE NW OF THIS CYCLONIC CIRCULATION...AND WAS 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. AS THIS MID LEVEL TROUGH IS FORCED SE TODAY...LOOK FOR ACTIVE CONVECTION TO PERSIST WITHIN THIS MOISTURE PLUME...AND BECOME VERY ACTIVE OVER LAND DURING THE DIURNAL CYCLE...WHERE HEAVY RAINFALL IS LIKELY TO OCCUR. 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. $$ STRIPLING