000 AXPZ20 KNHC 231622 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC THU MAY 23 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1430 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH AXIS EXTENDS FROM COLOMBIA NEAR 06.5N74.5W TO 13N87.5W TO LOW PRES NEAR 10.5N103W 1009 MB TO 08.5N118W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON TO 09N123W TO 11.5N133W TO BEYOND 07N140W. SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 180 NM S OF TROUGH BETWEEN 78W AND 86W...AND WITHIN 210 NM N AND 300 NM S OF TROUGH BETWEEN 90W AND 100W. SCATTERED TO LOCALLY NUMEROUS MODERATE TO STRONG CONVECTION NOTED WITHIN 90 NM N AND 180 NM S OF TROUGH BETWEEN 102W AND 116W. SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 90 NM S AND 180 NM N OF ITCZ BETWEEN 129W AND 135W. ...DISCUSSION... A GENERALLY RIDGE-TROUGH-RIDGE UPPER LEVEL PATTERN PREVAILS ACROSS THE DISCUSSION AREA THIS MORNING. THE TWO RIDGES ARE S OF 22N-24N AND SPAN BETWEEN 120W AND 144W...AND BETWEEN 70W AND 126W RESPECTIVELY...AND CONTINUE TO VENTILATE DEEP TROPICAL CONVECTION ALONG AND NEAR THE MONSOON TROF AND ITCZ DESCRIBED ABOVE. A SHORTWAVE TROUGH HAS MOVED OVER THE WESTERN RIDGE AND IS MOVING E-SE AND SLOWLY DIVING INTO THE BACK SIDE OF THE TROUGH PREVAILING BETWEEN THE TWO RIDGES...BETWEEN 110W AND 120W...AND HAS ERODED MODESTLY W PORTIONS OF THE EASTERN-MOST RIDGE. THE FORWARD PROGRESS OF THE MEAN UPPER TROUGH IS FORECAST TO END TONIGHT WHILE THE TROUGH SHARPENS OVER THE WEEKEND...AS THE TWO UPPER RIDGES AMPLIFY. AT LOW LEVELS...EPAC SURFACE RIDGE DOMINATES THE AREA W OF 110W...CENTERED ON A 1033 MB HIGH NEAR 41N143W...WITH RIDGE AXIS EXTENDING SE TO NEAR 18N112W. OVERNIGHT SCATTEROMETER PASSES INDICATED MINIMAL N-NW GALES CONTINUING OFF THE CENTRAL CALIFORNIA COAST...WITH FRESH N TO NE WINDS SPILLING S AND SW INTO NORTH PORTIONS OF THE DISCUSSION AREA N OF 24N. NORTHERLY SWELL GENERATED WITHIN THIS REGION OF WINDS CONTINUES TO PROPAGATE S AND SE...AND WAS PRODUCING SEAS OF 8 TO 13 FT ACROSS THE AREA N OF 24N...WITH HIGHEST SEAS WELL OFFSHORE OF BAJA CALIFORNIA NORTE. THE REMNANTS OF ALVIN WERE LOCATED ACROSS SW PORTIONS... PROPAGATING WWD AS A LARGE AMPLITUDE WAVE ALONG THE ITCZ AT 133W. A MODEST REGION OF FRESH NE WINDS AROUND 20 KT CONTINUE N OF THIS WAVE AND ARE PRODUCING SEAS 8-9 FT. THIS WAVE WILL CONTINUE W AND EXIT THE AREA IN THE NEXT 36 HOURS. AS IT PASSES DIRECTLY S OF THE EPAC HIGH...WINDS MAY INCREASE SLIGHTLY TO 20- 25 KT. E OF 110W...MODERATE MONSOONAL FLOW DOMINATES THE TROPICS AND IS PRODUCING CONVERGENCE OF ABUNDANT TROPICAL MOISTURE INVOF THE MONSOON TROUGH. SATELLITE IMAGERY THE PAST 24 HOURS HAS REVEALED A LOW TO MIDDLE LEVEL CYCLONIC CIRCULATION...AND SCATTERED TO NUMEROUS CONVECTION...NOW CURRENTLY INVOF 10N104W. A 1009 MB SURFACE LOW HAS DEVELOPED NEAR THERE NEAR 10.5N103W...WITH MOST CONVECTION NOW FLARING TO THE S AND SW OF THIS LOW. GLOBAL MODELS SUGGEST THERE IS SOME CHANCE FOR SLOW AND GRADUAL ORGANIZATION OF THIS LOW AS IT MOVES WWD DURING THE NEXT SEVERAL DAYS. FARTHER E...LOW TO MIDDLE LEVEL CYCLONIC TURNING IS ALSO NOTED CENTERED INVOF 08N87W. S TO SW MONSOONAL WINDS PREVAIL AT THE SURFACE IN THIS LOCATION...BUT AS THIS FEATURE DRIFTS W OVER THE WEEKEND IT IS EXPECTED TO BECOME BETTER ALIGNED WITH THE MONSOON TROUGH. STRENGTHENING HIGH PRES ACROSS THE SW N ATLANTIC IS EXPECTED TO ENHANCE THE TRADE WINDS ACROSS THE CENTRAL AND W CARIBBEAN BY THE EARLY PART OF THE UPCOMING WEEK...WHICH WILL INDUCE GAP WIND FLOW ACROSS CENTRAL AMERICA AND INTO THE EPAC. THIS SCENARIO WILL CREATE FAVORABLE LOW TO MIDDLE TROPOSPHERIC CONDITIONS FOR A WAVE TO DEVELOP AND GROW ACROSS THIS AREA AS IT SHIFTS WWD AND DOWNSTREAM OF THE GULFS OF PAPAGAYO AND TEHUANTEPEC. GLOBAL MODELS ARE PRESENTLY IN DISAGREEMENT IN THE STRENGTH OF DEVELOPMENT OF THIS WAVE...WITH THE GFS MODEL DEVELOPING A TROPICAL CYCLONE WITHIN THE NEXT 5 DAYS. THIS AREA IS BEING MONITORED FOR THIS POTENTIAL DURING THE UPCOMING WEEK. LONG PERIOD CROSS HEMISPHERIC SW SWELL AT 17-19 SECONDS IS MOVING THROUGH THE AREA WATERS THIS MORNING AND HAVE BEGUN TO INCREASE ALONG THE CENTRAL AMERICAN AND MEXICAN COASTS. OVERNIGHT ALTIMETER PASSES INDICATED THAT WW3 MODEL GUIDANCE WAS GENERALLY 1.5 TO 2 FT TOO LOW IN ITS FORECAST OF THIS SWELL. EXPECTED SW SWELL AND ADDITIONAL PULSES TO DOMINATE THE AREA WATERS THROUGH THE WEEKEND...AND PRODUCING STRONG AND DANGEROUS SURF ACROSS THE COASTS AND REEFS OF THE AREA COASTLINES. $$ STRIPLING