000 AXPZ20 KNHC 211603 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SUN AUG 21 2011 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 1545 UTC. ...ITCZ/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM 9N84W TO 15N96W TO 19N99W TO 1010 MB LOW NEAR 12N107W AND TO 10N114W. IT THEN RESUMES FROM 15N122W TO BEYOND THE AREA AT 9N140W. SCATTERED ISOLATED STRONG FROM 09N TO 15N BETWEEN 92W AND 100W. ...DISCUSSION... W OF 120W... AN ELONGATED UPPER LEVEL LOW CENTERED JUST N OF THE AREA NEAR 32N128W IS MOVING S ABOUT 15 KT. A TROUGH EXTENDS FROM THE LOW SW TO NEAR 30N136W. A HIGHLY AMPLIFIED UPPER RIDGE IS TO THE NW OF THE LOW. ANOTHER UPPER LOW IS W OF THE AREA NEAR 33N147W. THE UPPER LOW NEAR 31N128W IS FORECAST TO DROP NEAR 30N128W BY MON EVENING AS IT BECOMES CUT-OFF FROM THE NORTHERN STREAM JET STREAM BRANCH. ELSEWHERE AN UPPER LEVEL ANTICYCLONE IS ANCHORED NEAR 19N141W WITH A RIDGE EASTWARD TO 125W. A NARROW UPPER TROUGH IS ALONG 123W WITH A POSSIBLE SMALL UPPER LEVEL LOW FORMING NEAR 24N123W. AT THE SURFACE...THE REMNANT LOW OF FORMER TROPICAL DEPRESSION GREG IS UNDER THIS TROUGH AT THE POSITION OF 20.2N 122.8W 1008 MB AT 1500 UTC MOVING W AT 8 KT...WITH MAXIMUM WINDS OF 30 KT GUSTS TO 40 KT. IT IS MARKED BY A LARGE SWIRL OF LOW AND MID LEVEL CLOUDS WITH SCATTERED SHOWERS WITHIN 240 NM IN THE W SEMICIRCLE AND WITHIN 120 NM IN THE E SEMICIRCLE OF THE THE CENTER. THE LOW IS FORECAST TO WEAKEN TO FURTHER THROUGH THE NEXT 48 HOURS AS IT REACHES NEAR 20N128W. SATELLITE WATER VAPOR IMAGERY SHOWS MODERATE SUBSIDENCE COVERING MUCH OF THIS PORTION OF THE AREA INCLUDING THE UPPER ATMOSPHERE OVER THE WEST SIDE OF THE REMNANT LOW OF GREG. THIS IS ALLOWING FOR THE ATMOSPHERE TO REMAIN RATHER DRY AND STABLE INHIBITING DEEP CONVECTION FROM FORMING ALONG AND NEAR THE MONSOON TROUGH. UPPER LEVEL MOISTURE IS STREAMING SWD INTO THE AREA BETWEEN THE UPPER LOW NEAR 32N128W AND THE UPPER RIDGE TO ITS NW. ELSEWHERE AT THE SURFACE...A WEAK 1021 MB HIGH IS N OF THE AREA AT 36N137W WITH A RIDGE SE TO 27N120W. WEAK HIGH PRES COVERS THE AREA GENERALLY TO THE N OF 24N. E OF 120W...A LARGE AND NEARLY STATIONARY ANTICYCLONE ANCHORED OVER NRN TEXAS EXTENDS A RIDGE SW TO ACROSS CENTRAL BAJA CALIFORNIA...AND TO NEAR 24N120W. A SMALL UPPER LEVEL LOW IS OVER CENTRAL MEXICO AT 23N107W. THE UPPER FLOW IS SQUEEZED IN BETWEEN BOTH OF THESE FEATURES...AND IS ADVECTING UPPER LEVEL DEBRIS MOISTURE ASSOCIATED FROM SCATTERED CONVECTION THAT OCCURRED DURING THE OVERNIGHT HOURS ALONG THE W COAST OF MEXICO FROM CABOS CORRIENTES NWD TO 27N111W WESTWARD TO NEAR SRN BAJA CALIFORNIA. THE FLOW PATTERN TO SW OF THE UPPER LEVEL LOW OVER MEXICO IS RATHER DIFFLUENT BETWEEN 102W-115W. AT THE SURFACE...A WEAK 1010 MB LOW ON THE MONSOON TROUGH IS MOVING SLOWLY WNW IS NEAR 12N106W. THE UPPER LEVEL ELY FLOW THROUGHOUT THIS AREA IS SHEARING SCATTERED STRONG CONVECTION THAT IS OCCURRING WITHIN 60-220 NM NW OF THE LOW CENTER. THE LOW IS FORECAST TO REACH NEAR 13N108W IN ABOUT 24 HOURS...AND TO NEAR 13N111W IN 48 HOURS. UPPER LEVEL ELY SHEAR WILL PERSIST DURING THIS TIME. SW 20 KT WINDS WILL CONTINUE TO FEED INTO THE MONSOON TROUGH IN THE VICINITY OF THE LOW FROM ABOUT 9N TO 13N BETWEEN 105W-111W OVER THE NEXT 48 HOURS WITH SEAS TO 9 FT. SATELLITE WATER VAPOR IMAGERY SHOWS ABUNDANT UPPER LEVEL MOISTURE STREAMING WESTWARD IN THE UPPER LEVEL ELY OVER THIS PORTION OF THE AREA...ALTHOUGH VISIBLE IMAGERY SHOWS BROAD AND DISORGANIZED CLOUDINESS AND CONVECTION AS DESCRIBED ABOVE TO THE S OF THE MONSOON TROUGH BETWEEN 92W-100W AND UPSTREAM OF THE 1010 MB LOW AT 12N106W. ALSO WITH RESPECT TO MARINE ISSUES...LONG PERIOD CROSS-EQUATORIAL SWELLS RESULTING IN SEAS TO 9 FT WILL BE CONFINED TO S OF 9N BETWEEN 98W-116W. ACCORDING TO WAVEWATCH MODEL GUIDANCE THESE SWELLS SHOULD LAST THROUGH THE NEXT 48 HOURS. $$ AGUIRRE