000 AXPZ20 KNHC 131500 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC WED MAY 13 2015 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 1500 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE ITCZ EXTENDS FROM 06N93W TO 06N107W TO 08.5N116W TO 05N119W. IT RESUMES FROM 05N122W TO 09N130W. IT RESUMES FROM 08N134W TO 07N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED WITHIN 120 NM OF AXIS BETWEEN 93W AND 106W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED FROM 02N TO 07N BETWEEN 106W AND 114W. SCATTERED MODERATE CONVECTION WAS NOTED FROM 08N TO 11N BETWEEN 111W AND 118W. SCATTERED MODERATE CONVECTION WAS NOTED FROM 02N TO 10N BETWEEN 120W AND 131W. ...DISCUSSION... AS EVIDENT FROM THE PREVIOUS SECTION...THERE IS A LOT OF CONVECTIVE ACTIVITY ACROSS THE TROPICAL EASTERN NORTH PACIFIC S OF 10N. THIS IS IN RESPONSE TO A KELVIN WAVE PROPAGATING ACROSS THE AREA. THIS ACTIVE CONVECTION HAS HELPED FOR A COUPLE OF PERTURBATIONS WITHIN THE ITCZ. THE FIRST PERTURBATION IS ANALYZED AS A TROUGH FROM 12N118W TO 07N122W WHILE THE SECOND PERTURBATION HAS MORE CIRCULATION ASSOCIATED WITH IT AND IS ANALYZED AS A LOW CENTERED NEAR 09N131W. HIGH PRESSURE OF 1031 MB CENTERED NW OF THE AREA NEAR 37N149W EXTENDS A RIDGE SE TO NEAR 20N110W. THE PRESSURE GRADIENT BETWEEN THE AREA OF HIGH PRESSURE AND LOWER PRESSURE IN THE VICINITY OF THE ITCZ...AND PERTURBATIONS WITHIN THE ITCZ...IS MAINTAINING MODERATE TO FRESH TRADEWINDS OVER THE WESTERN WATERS N OF THE ITCZ TO NEAR 20N AS NOTED IN THE MOST RECENT SCATTEROMETER PASSES. THE SURFACE RIDGE IS EXPECTED TO WEAKEN AND SHIFT SW OVER THE NEXT 48 HOURS. THE AREA OF FRESH TRADES WILL SHRINK IN RESPONSE. THE SURFACE LOW IS CURRENTLY FORECAST TO DISSIPATE WHILE A TIGHTER CIRCULATION IS EXPECTED TO DEVELOP WITHIN THE TROUGH NEAR 120W. THE DEEPENING OF THE TROUGH WILL HELP TO CREATE A LOCALIZED TIGHT PRESSURE GRADIENT TO THE N OF THE LOW WHICH WILL ALLOW FOR THE RETURN OF FRESH TRADES. LONG PERIOD CROSS EQUATORIAL SOUTHERLY SWELL AT 19-22 SECONDS IS CURRENTLY AFFECTING THE MEXICAN AND CENTRAL AMERICAN COAST. THIS LONG PERIOD SWELL WILL LEAD TO HAZARDOUS SURF AND BEACH CONDITIONS ALONG THE MEXICAN AND CENTRAL AMERICAN COASTS THROUGH TONIGHT. SEA HEIGHTS OF 8 FT OR GREATER IN SW SWELL WILL PRIMARILY IMPACT THE AREAS S OF 12N E OF 120W...EXCEPT IN THE LEE OF THE GALAPAGOS ISLANDS...THROUGH TONIGHT BEFORE GRADUALLY SUBSIDING TO S OF THE EQUATOR BY 48 HOURS. A COLD FRONT IS FORECAST TO APPROACH THE AREA THU WITH ASSOCIATED AREA OF 8-9 FT SEAS IN NW SWELL MOVING INTO THE FAR N WATERS BY THU NIGHT. THE COLD FRONT WILL MOVE INTO THE AREA EARLY FRI AND EXTEND FROM NEAR 30N120W TO 28N126W. WINDS WILL STRENGTHEN FRI MORNING AS THE FRONT MOVES INTO THE AREA WITH SEAS CONTINUING TO BUILD IN NW SWELL...REACHING NEAR 11 FT BY FRI MORNING. GULF OF CALIFORNIA...THE PRES GRADIENT BETWEEN THE HIGH PRESSURE RIDGE AND TROUGHING OVER THE SW UNITED STATES CONTINUES TO SUPPORT FRESH TO STRONG SOUTHERLY WINDS N OF 29.5N W. THESE WINDS WILL DIMINISH BY THIS AFTERNOON...THEN WILL INCREASE AGAIN LATE TONIGHT INTO EARLY THU AS A NEW IMPULSE LOWERS THE SURFACE PRES ACROSS THE SW UNITED STATES. SW WINDS IN THE NORTHERN GULF OF CALIFORNIA ARE EXPECTED TO INCREASE TO NEAR GALE FORCE THU EVENING BEFORE ONCE AGAIN DIMINISHING TO 20 KT OR LESS FRI MORNING. ANOTHER PULSE IS EXPECTED FRI NIGHT WITH MODEL GUIDANCE INDICATING THE POTENTIAL FOR WINDS TO REACH MINIMAL GALE FORCE LATE FRI NIGHT THROUGH SUNRISE SAT. THIS SITUATION WILL BE MONITORED FOR THE POTENTIAL OF A GALE WARNING. GULF OF TEHUANTEPEC...A TIGHT PRESSURE GRADIENT BETWEEN A BROAD SURFACE TROUGH OVER THE SW GULF OF MEXICO AND HIGH PRESSURE OVER THE COASTAL PLAIN OF MEXICO IS SUPPORTING STRONG TO NEAR GALE WINDS FUNNELING THROUGH THE GULF OF TEHUANTEPEC. WINDS WILL DIMINISH TO 20 KT OR LESS THIS AFTERNOON AS THE SURFACE TROUGH CONTINUES TO SHIFT W OF THE BAY OF CAMPECHE. ANOTHER TROUGH WILL DEVELOP AND SHIFT OFF THE YUCATAN PENINSULA TONIGHT. THIS WILL ONCE AGAIN INCREASE THE PRESSURE GRADIENT OVER THE SW GULF. THE GRADIENT WILL NOT BE AS STRONG AS THIS MORNING WITH STRONG WINDS EXPECTED TO FUNNEL INTO THE GULF OF TEHUANTEPEC LATE TONIGHT INTO EARLY THU. WINDS WILL DIMINISH TO 20 KT OR LESS BY THU AFTERNOON AND ARE EXPECTED TO REMAIN BELOW ADVISORY CRITERIA THROUGH THU NIGHT. GULF OF PAPAGAYO...THE PRES GRADIENT BETWEEN RIDGING OVER THE NW CARIBBEAN SEA AND LOWER PRESSURE IN THE VICINITY OF THE ITCZ IS SUPPORTING WINDS TO NEAR GALE FORCE THIS MORNING. THE PRES GRADIENT WILL RELAX SLIGHTLY BY THIS AFTERNOON WITH FRESH TO STRONG WINDS PREVAILING. FRESH TO STRONG WINDS WILL CONTINUE THROUGH THU AFTERNOON BEFORE DIMINISHING TO 20 KT OR LESS. WINDS WILL ONCE AGAIN PULSE TO FRESH TO STRONG THU NIGHT INTO FRI MORNING. GULF OF PANAMA...FRESH TO STRONG NORTHERLY WINDS IN THE GULF OF PANAMA WILL DIMINISH TO 20 KT OR LESS BY THIS AFTERNOON. COMBINED SEAS IN THE 8-9 FT RANGE DUE TO THE NORTHERLY WIND WAVES AND LONG PERIOD SW SWELL WILL SUBSIDE TO LESS THAN 8 FT BY THE AFTERNOON. $$ AL