000 AXPZ20 KNHC 211622 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC FRI MAY 21 2010 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 1445 UTC. ..TROPICAL WAVES... TROPICAL WAVE EXTENDING FROM FAR EPAC NEAR 04N83W NE INTO SW CARIBBEAN TO NEAR 12N77W IS CURRENTLY MOVING THROUGH THE COLOMBIAN CYCLONIC GYRE...INFLUENCING THE NE TO SW HORIZONTAL TILT. SELY LOW TO MID LEVEL FLOW ACROSS THE WRN CARIBBEAN IS ADVECTING MOISTURE ASSOCIATED WITH THIS LOW TOWARD THE NW AND WILL LIKELY LEAD TO SOME FRACTURING OF THE N PORTION OF THIS WAVE AS IT MOVES TOWARDS THE N COAST OF HONDURAS OVER THE NEXT FEW DAYS...WHILE THE REMAINDER OF THE WAVE DRIFTS W TO WNW. ACTIVE CONVECTION IS EXPECTED TO CONTINUE TO PULSE ON THE E SIDE OF THIS WAVE AS IT REMAINS IN A FAVORABLE UPPER ENVIRONMENT FOR TSTM DEVELOPMENT. TROPICAL WAVE ALIGNED NE TO SW AND CENTERED ON MID LEVEL CYCLONIC CIRCULATION CENTER NEAR 09.5N87W...MOVING NW 5 TO 10 KT PAST 24 HOURS. THIS MID LEVEL VORTEX APPEARED A FEW DAYS AGO ACROSS INTERIOR COLOMBIA AND HAS BECOME MORE EVIDENT AGAIN IN THE PAST 24 HOURS. SCATTERED MODERATE TO STRONG CONVECTING WAS OCCURRING FROM 05N TO 12N BETWEEN 86W AND 89W...AND HAS BEEN DECREASING IN COVERAGE PAST FEW HOURS. A LOW TO MID LEVEL CYCLONIC GYRE CONTINUES ACROSS THE EPAC E OF 92W AND HAS SIGNIFICANTLY ALTERED TYPICAL WWD SPEED AND MOTION OF THIS WAVE THE PAST FEW DAYS. MOISTURE ASSOCIATED WITH THIS WAVE HAS ADVECTED NW AS FAR AS HONDURAS AND CONTRIBUTED TO STRONG NOCTURNAL CONVECTION ACROSS CENTRAL AMERICA E OF 90W. BOTH THIS WAVE AND THE WAVE TO ITS E LIE IN A REGION OF BROAD UPPER DIFFLUENCE AND WITHIN A RELATIVE MAXIMUM OF LOW TO MID LEVEL MOISTURE. THESE CONDITIONS ARE EXPECTED TO PERSIST FOR THE NEXT FEW DAYS AND SHOULD CONTINUE TO SUPPORT CONVECTION NEAR THESE SLOW MOVING TROPICAL WAVES. CONVECTION ASSOCIATED WITH THIS WAVE IS LIKELY TO CONTINUE PRIMARILY ACROSS THE E AND SE QUADRANTS AS THE WAVE MOVES VERY SLOWLY W TO WNW OVER THE NEXT 48 HOURS. TROPICAL WAVE ALONG 117W S OF 12N MOVING W AT 15 KT HAS WEAKENED CONSIDERABLY AND MAY BECOME DIFFICULT TO TRACK. UPPER LEVEL SWLY SHEAR IS ACTING TO REDUCE AND LIMIT ASSOCIATED CONVECTION. THE REMNANTS OF THIS FEATURE WILL CONTINUE TO MOVE W AND ACCELERATE TO 15-20 KT AS IT MOVES S OF THE EPAC LLVL RIDGE CURRENTLY IN PLACE. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ALONG 09N78W TO 08N81W TO 09N93W TO 07N105W THEN CONTINUES FROM 09N110W TO 08N130W TO 06N140W. SCATTERED TO LOCALLY NUMEROUS MODERATE TO STRONG WITHIN 120 NM N AND 60 NM S OF AXIS BETWEEN 91W AND 99W. SCATTERED MODERATE FROM 06N TO 10N BETWEEN 102W AND 110W. SCATTERED MODERATE TO STRONG WITHIN 90 NM EITHER SIDE OF AXIS W OF 134W. ...DISCUSSION... A BROAD HIGH PRES RIDGE CENTERED ON A 1029 MB HIGH NEAR 35N151W DOMINATES THE SURFACE PATTERN N OF 15N AND W OF 110W. THERE IS A TIGHT PRES GRADIENT IN PLACE BETWEEN THIS RIDGING AND TROUGHING FROM THE SW U.S. THROUGH CENTRAL MEXICO....PRODUCING FRESH TO STRONG NW TO N WINDS FROM OFFSHORE OF CENTRAL CALIFORNIA...WHERE AN AREA OF GALE FORCE WINDS IS FOUND...TO ALONG THE W COAST OF BAJA CALIFORNIA WHERE WINDS WERE IN THE 25-30 KT RANGE NEAR 30N...ACCORDING TO SHIPS DGSE AND ZCBU3...BOTH NEAR 29N117W AT 0600 UTC...DIMINISHING TO 20-25 KT S TO 24N. THIS STRONG PRES GRADIENT OVER NE WATERS WILL BE MAINTAINED THE NEXT FEW DAYS AS THE GENERAL PATTERN BECOMES LESS PROGRESSIVE...WITH A MEAN TROUGH OVER THE WESTERN U.S. AND RIDGING OVER THE CENTRAL N PACIFIC. LOOK FOR NE TRADE WINDS BETWEEN THE HIGH AND THE ITCZ...CURRENTLY IN THE 20-25 KT RANGE ACCORDING TO THE 0612 UTC ASCAT PASS...TO REMAIN IN PLACE GENERALLY W OF 125W THROUGH SUN EVENING. SEAS IN THIS REGION OF FRESH TRADES WILL GROW TO 9-10 FT BY SAT MORNING IN NE WIND WAVES AND A MIX OF LONG PERIOD NW AND S SWELL. AN UPPER LEVEL ANTICYCLONE WAS SHIFTED N OVER CENTRAL HONDURAS OVERNIGHT...AS VERY ACTIVE NOCTURNAL CONVECTION OVER THAT REGION OF CENTRAL AMERICA OCCURRING LAST NIGHT. THE ASSOCIATED RIDGE EXTENDS WWD ALONG 15N TO 115W AND NE INTO THE W CENTRAL CARIBBEAN. ACTIVE CONVECTION ALONG THE ITCZ AND NEAR TROPICAL WAVES MOVING THROUGH THE COLOMBIAN CYCLONIC GYRE WILL MAINTAIN ACTIVE AND PULSING CONVECTION ACROSS THIS REGION...AND HELP TO MAINTAIN THIS UPPER RIDGING AND UNSTABLE ENVIRONMENT. MEANWHILE...A 50-60 KT W-SW UPPER JET PARALLELS THE RIDGE AXIS WITH ITS JET CORE WITHIN 5 DEG NW OF THIS RIDGE. A 1010 MB LOW PRES CENTER IS EMBEDDED IN THE ITCZ NEAR 08N130W. THIS SURFACE LOW HAS MOVED UNDERNEATH UPPER LEVEL RIDGING...WITH CONVECTION INCREASING TO THE E OF THE LOW DURING THE PAST 6 HOURS. LARGE CROSS-EQUATORIAL LONG PERIOD SW SWELL HAS REACHED MUCH OF THE PACIFIC COASTLINE WITHIN THE FORECAST AREA WITH WAVE HEIGHTS IN THE 6-8 FT RANGE AT 15 TO 16 SECONDS. THE EXCEPTION TO THIS BEING THE W COAST OF BAJA CALIFORNIA WHERE NW WIND WAVES HAVE DRIVEN SEAS UP TO 8-13 FT. A NEW PULSE OF S-SW SWELL HAS JUST BEGUN TO HIT THE COASTS OF CENTRAL AMERICA THIS MORNING AND WILL DRIVE TO 9-10 FT AT 16-17 SECONDS BY SAT MORNING. THIS WILL GENERATE VERY LARGE AND POWERFUL SURF ALONG THE COASTLINES...REEFS AND SHOALS FROM BAJA CALIFORNIA TO PERU...MAKING FOR EXTREMELY DANGEROUS SURF CONDITIONS. THESE SWELLS WILL BEGIN TO FADE BY SUNDAY NIGHT. $$ STRIPLING