000 AXPZ20 KNHC 202155 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC TUE MAY 20 2014 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A MONSOON TROUGH EXTENDS NW FROM THE COAST OF COLOMBIA AT 06N77W TO THE PACIFIC COAST OF COSTA RICA AT 09N83W...THEN TURNS SW TO 06N93W...THEN NW TO A 1008 MB LOW PRESSURE AT 10N105W. A SECOND LOW PRESSURE IS AT 12N116W AND ESTIMATED AT 1011 WITH A MONSOON TROUGH EXTENDING SW TO 08N120W WHERE SCATTEROMETER WINDS INDICATE A TRANSITION TO AN ITCZ. THE ITCZ CONTINUES SW TO BEYOND 04N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION...ACCOMPANIED BY FREQUENT LIGHTNING...IS OBSERVED ALONG THE EASTERN SEGMENT OF THE MONSOON TROUGH FROM 01-09N TO THE E OF 88W...AND EXTENDS ACROSS PANAMA AND OVER THE CARIBBEAN APPROACHES TO THE PANAMA CANAL. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED OVER THE NE QUADRANT OF THE LOW AT 10N105W...WITHIN 150 NM EITHER SIDE OF A LINE FROM 12N100W TO 11N106W. SIMILAR CONVECTION IS OBSERVED OVER THE SE SEMICIRCLE OF THE LOW AT 12N116W...ROUGHLY WITHIN 120 NM EITHER SIDE OF A LINE FROM 14N112W TO 10N117W...AND CONTINUES W TO 07N125W TO 08N132W. THE LOW PRESSURE AT 10N105W IS EXPECTED TO DRIFT W-NW THROUGH THE WEEKEND WITH GUIDANCE SUGGESTING DEEPENING OF THE LOW NEAR 12N112W EARLY NEXT WEEK. THE LOW PRESSURE NEAR 12N116W IS EXPECTED TO REMAIN QUASI-STATIONARY AND GRADUALLY LOSE IDENTITY IN THE MONSOON TROUGH AS IT CONTINUES E INTO THE LOW PRESSURE CURRENTLY NEAR 10N105W. ISOLATED MODERATE CONVECTION IS OBSERVED WELL N OF THE MONSOON TROUGH FROM 10-16N BETWEEN 87-100W. ...DISCUSSION... AN UPPER ANTICYCLONE IS ESTIMATED NEAR 11N140W WITH A SHORTWAVE RIDGE EXTENDING N ALONG 142W TO A SHARP CREST AT NEAR 36N141W. AN UPPER ANTICYCLONE IS OVER S-CENTRAL TEXAS WITH AN UPPER RIDGE DOMINATING THE CENTRAL CONUS. AN UPPER CYCLONE IS BETWEEN THESE TWO RIDGES AT 37N119W...WITH AN UPPER TROUGH EXTENDING S TO BASE OVER THE TROPICAL PACIFIC AT 10N120W. SOME UPPER MOISTURE IS SPILLING E AND SE ACROSS THE UPPER RIDGE AT 31N140W TO NEAR 28N136W. ANOTHER NARROW BAND OF UPPER MOISTURE IS NOTED JUST E OF THE UPPER TROUGH WITHIN 60 NM EITHER SIDE OF A LINE FROM 28N125W TO OVER ARIZONA AT 36N113W. OTHERWISE...THE UPPER LEVELS APPEAR VERY DRY N OF 13N W OF 115W. AN UPPER ANTICYCLONE IS OVER THE DEEP TROPICS NEAR 07N126W WITH A RIDGE EXTENDING W TO 10N134W...AND ENHANCING CONVECTION ALONG THE ITCZ BETWEEN 120-138W. ANOTHER UPPER ANTICYCLONE IS CENTERED NEAR 14N100W AND ENHANCING CONVECTION NEAR THE LOW PRESSURE AT 12N116W...AND ALONG THE MONSOON TROUGH TO ITS SW. ONLY ISOLATED CONVECTION IS OBSERVED ELSEWHERE UNDER THE RIDGE BETWEEN 90- 110W. DEBRIS MOISTURE IS STREAMING NE AND E ACROSS CENTRAL AMERICA FROM 13-22N. AN UPPER ANTICYCLONE IS ESTIMATED NEAR 06N80W AND IS ENHANCING THE CONVECTION ALONG THE EASTERN SEGMENT OF THE MONSOON TROUGH AS PREVIOUSLY DESCRIBED. A SURFACE RIDGE EXTENDS FROM 32N134W TO 19N111W. ANTICYCLONIC SURFACE WINDS ARE GENERALLY AT 15-20 KT AROUND THE PERIPHERY OF THIS RIDGE...EXCEPT NORTHWESTERLY 20-25 KT WINDS ARE EXPECTED TO THE N OF 28N E OF 116W TO THE BAJA PENINSULA FOR THE NEXT 12 HOURS OR SO. GULF OF TEHUANTEPEC...THE NOCTURNAL NORTHERLY DRAINAGE FLOW WILL MAX AT 20 KT TONIGHT AND EACH NIGHT THROUGH THU NIGHT...THEN WEAKEN TO A 15 KT MAX ON FRI NIGHT. $$ NELSON