000 AXPZ20 KNHC 230949 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0930 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS W FROM NICARAGUA AT 12N86W TO 13N99W...THEN SW THROUGH AN EMBEDDED 1010 MB LOW PRES NEAR 10.5N101.5W WITH THE TROUGH CONTINUING WSW TO 08N120W WHERE SCATTEROMETER WINDS INDICATE AN ITCZ AXIS FORMS. THE ITCZ EXTENDS NW TO 11N132W WHERE THE REMNANT TROUGH OF FORMER TROPICAL CYCLONE ALVIN IS ANALYZED FROM 03N137W TO 13N133W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS WITHIN 120 NM OF 08N120W...AND 180 NM EITHER SIDE OF A LINE FROM 10N86W TO 09N114W. SIMILAR CONVECTION HAS FORMED S OF THE ITCZ WITHIN 30 NM EITHER SIDE OF A LINE FROM 06N127W TO 12N133W. GUIDANCE IS SUGGESTING THE EMBEDDED SURFACE LOW AT 10.5N101.5W WILL MOVE W ALONG THE MONSOON TROUGH AXIS TO NEAR 10N103W TONIGHT...NEAR 11N104W ON THU NIGHT AND NEAR 10N107W ON FRI NIGHT BUT NOT HAVE ANY SIGNIFICANT DEVELOPMENT. AN ILL-DEFINED TROPICAL WAVE HAS MOVED INTO THE SW CARIBBEAN AND IS EXPECTED TO SLOW AS IT MOVES ACROSS COSTA RICA ALONG THE MONSOON TROUGH INTO THE EPAC LATE TONIGHT. GUIDANCE CONTINUES TO SUGGEST THE WAVE WILL HELP SPAWN A WEAK LOW PRESSURE NEAR 10N87W BY EARLY FRI. MODEL GUIDANCE IS SOMEWHAT IN AGREEMENT WITH THIS LOW FORMING AND MOVING SLOWLY W ALONG THE MONSOON TROUGH AXIS OVER THE WEEKEND. THE GFS MODEL CONTINUES TO BE MUCH MORE AGGRESSIVE THAN OTHER GUIDANCE...AND DEVELOPS THE LOW INTO A TROPICAL CYCLONE. I BLENDED AND SMALL PERCENTAGE OF THE LATEST GFS INTO THE PREVIOUS PACIFIC GRIDS...WHICH IN TURN CONSISTED OF A GFS AND ECMWF BLEND. I TONED DOWN THE WINDS AND WIND GUSTS CONSERVATIVELY TO A SLOWLY DEVELOPING LOW NEAR 09N93W LATE SUN...NEAR 11N95W LATE MON...AND NEAR 13N96W LATE TUE WITH CYCLONIC WINDS THEN AT 20-30 KT...WITH MAX SEAS TO ABOUT 18 FT. MODEL GUIDANCE CONTINUES TO SUGGEST THE NORTHERLY DRAINAGE FLOW WILL INCREASE TO 15-20 KT IN THE GULF OF TEHUANTEPEC ON FRI NIGHT AND PULSE AT 15-20 KT LATE AT NIGHT THROUGH SUNRISE EACH MORNING THROUGH THE WEEKEND. THE STRENGTH OF THESE DRAINAGE WINDS WILL BE HIGHLY INFLUENCED BY THE STRENGTH AND TRACK OF THE TROPICAL LOW TO THE S. EXPECT MANY FLUCTUATIONS IN THE GRIDS THROUGH THE EXTENDED PERIODS. A SURFACE RIDGE EXTENDS FROM NW TO SE FROM 32N136W TO 18N112W. NW WINDS ARE CURRENTLY AT 10-15 KT ALONG THE ENTIRE W SHORE OF THE BAJA CALIFORNIA PENINSULA WITH SEAS CURRENTLY AT 4-5 FT EXCEPT 5-6 FT NEAR THE SOUTHERN TOP OF THE BAJA PENINSULA PER A RECENT ALTIMETER PASS. SEAS OF 6-8 FT PRIMARILY IN NW SWELL ARE EXPECTED TO REACH ALONG THE BAJA PENINSULA TO THE N OF 28N LATER TODAY...AND REACH AS FAR S AS 25N ON FRI. NORTHERLY WINDS AT 15-20 KT CONTINUE ACROSS THE N-CENTRAL PACIFIC WATERS FROM 24-30N BETWEEN 116W-140W WITH SEAS MAXING AT 12-13 FT IN THE ASSOCIATED N SWELL ACROSS THE AREA FROM 28-30N BETWEEN 118-124W. NOTE THAT N WINDS ARE AT 20-25 KT IN THE DISCUSSION WATERS FROM 30-32N BETWEEN 118-125W...WITH SEAS 13-15 FT. ALTHOUGH N WINDS WILL BE ONLY IN THE 15-20 KT RANGE...THE N SWELL RESULTING IN SEAS TO 8 FT...WILL PROPAGATE S TO ALONG 10N W OF 115W BY LATE FRI NIGHT...THEN BEGIN TO SUBSIDE FROM THE NW ON SAT. NE TRADES CONTINUE ARE AT 15-20 KT WITHIN 240 NM W OF THE REMNANT TROUGH OF ALVIN. THE TROUGH IS EXPECTED TO CONTINUE TO SHIFT SLOWLY W REACHING FROM 11N140W TO 15N135W TONIGHT AND SHIFT W OF 140W ON FRI. $$ NELSON