000 AXPZ20 KNHC 201601 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SUN MAY 20 2012 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. ...SPECIAL FEATURES... 1006 MB LOW PRES CENTER NEAR 09.5N98.5W REMAINS EMBEDDED IN THE MONSOON TROUGH...AND HAS BEEN RELOCATED ABOUT 90 NM S-SE FROM PREVIOUS SATELLITE ESTIMATES BASED ON RECENT VISIBLE IMAGERY SHOWING DEFINITIVE LOW CLOUD LINES ARCHING INTO MID LEVEL CYCLONIC TURNING CENTERED NEAR 08N99W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 90 NM W SEMICIRCLE OF THE ESTIMATED CENTER...WHILE SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS OCCURRING BETWEEN 90 NM AND 300 NM OF THE SW QUADRANT. NUMERICAL MODEL GUIDANCE SUGGESTS SOME SLOW DEVELOPMENT OF THIS SYSTEM OVER THE NEXT SEVERAL DAYS....WITH ATMOSPHERIC CONDITIONS IMPROVING FOR DEVELOPMENT BY 48 HOURS. THERE IS A MODERATE CHANCE OF THIS LOW DEVELOPING INTO A TROPICAL CYCLONE IN THE NEXT 48 HOURS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM 10N84W TO 12N93W TO LOW PRES NEAR 09.5N98.5W 1006 MB TO 07N120W...THEN TRANSITIONS TO ITCZ AXIS...CONTINUING ON TO 06N126W TO BEYOND 04N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 150 NM N OF TROUGH AXIS E OF 88W. SCATTERED LOCALLY NUMEROUS MODERATE ISOLATED STRONG CONVECTION FROM 02.5N TO 08N BETWEEN 84W AND 95W. SCATTERED TO LOCALLY NUMEROUS MODERATE TO STRONG CONVECTION N OF 12.5N TO COAST BETWEEN 92W AND 95W. ...DISCUSSION... A BROAD TROPICAL RIDGE ALOFT IS CENTERED ON A SMALL UPPER ANTICYCLONE OVER GUATEMALA...WITH RIDGE GENERALLY S OF 20N EXTENDING E TO 65W AND W TO 112W. LIGHT N TO NE ANTICYCLONIC WIND SHEAR ON THE S SIDE OF THE RIDGE...S OF 10N...IS MAINTAINING A VERY FAVORABLE ENVIRONMENT FOR DEEP CONVECTIVE GROWTH. ABUNDANT TROPICAL MOISTURE...WITH VALUES IN THE 2.0-2.5 INCH RANGE...IS POOLED S OF THE MONSOON TROUGH AND E OF 105W. SCATTERED MODERATE TO STRONG CONVECTION CONTINUES TO PULSE IN CLUSTERS ACROSS THIS VERY UNSTABLE REGION...FURTHER ENHANCING DIVERGENCE ALOFT...AND AIDING IN THE MAINTENANCE OF THE RIDGING ALOFT. A FRESH TO STRONG BREEZE THROUGH ISTHMUS OF TEHUANTEPEC HAS BEGUN TO BE FORCED BY THE PRES GRADIENT BETWEEN RIDGING IN THE WESTERN GULF OF MEXICO AND STATIONARY TROUGHING OVER THE E COAST OF THE YUCATAN PENINSULA THIS MORNING...YIELDING NLY WINDS 20-25 KT THROUGH THIS PACIFIC GULF. HIGH PRES OVER THE U.S. GULF COAST STATES WILL RETROGRADE WESTWARD TODAY AND WEAKEN AS IT SINKS SOUTHWARD INTO THE NW GULF TOMORROW. THE PRES GRADIENT WILL REMAIN STRONG BETWEEN THIS RIDGING AND THE LOWERING PRESSURES TO THE SOUTH ASSOCIATED WITH THE LOW PRES SYSTEM DISCUSSED IN THE SPECIAL FEATURES SECTION ABOVE . THIS WILL ALLOW WINDS TO REMAIN FRESH TO STRONG HERE THROUGH AT LEAST EARLY TUE...WITH THE PLUME EXPECTED TO EXTEND DOWNSTREAM TO BEYOND 97W. THE RELATIVELY WEAK 1021 MB SUBTROPICAL HIGH NEAR 31N132W EXTENDS A RIDGE ACROSS THE FAR NW CORNER OF THE FORECAST AREA TO JUST N OF THE HAWAIIAN ISLANDS. A COLD FRONT ENCROACHING ON THE HIGH FROM THE NW WILL FORCE IT SOUTHWESTWARD TO 30N140W TODAY WHERE IT WILL GRADUALLY STRENGTHEN THROUGH EARLY TUE. THE PRES GRADIENT IS STRONG ENOUGH ON THE E SIDE OF THIS HIGH TO GENERATE A MODERATE TO FRESH N BREEZE WELL OFF THE BAJA PENINSULA OVER NE WATERS THAT WILL PERSIST THROUGH EARLY MON. AS THE HIGH BUILDS MON...THE PRES GRADIENT BETWEEN IT AND THE ITCZ WILL STRENGTHEN AND THE AREA OF FRESH WINDS WILL EXPAND SOUTHWESTWARD FROM NE WATERS TO ENCOMPASS THE USUAL TRADE WINDS REGION OVER THE W CENTRAL WATERS...AND BUILD SEAS TO AROUND 8 FT THERE. THE REMNANTS OF FORMER TROPICAL CYCLONE ALETTA ARE CURRENTLY NEAR 12N112W SINKING SLOWLY S. THE CENTER OF THIS WEAKENING 1007 MB LOW PRES SYSTEM IS BEGINNING TO BECOME ELONGATED AS SUGGESTED BY THE 0428 UTC ASCAT PASS. THE LOW IS EXPECTED TO BECOME FURTHER DISORGANIZED AND OPEN UP INTO AN ELONGATED TROUGH THROUGH THIS EVENING. THESE IS NO SIGNIFICANT CONVECTION ASSOCIATED WITH THE REMNANTS OF ALETTA...ONLY A SWIRL OF LOW LEVEL STRATOCUMULUS CLOUDS. $$ STRIPLING