000 AXPZ20 KNHC 011600 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC THU SEP 30 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 1545 UTC. ...ITCZ... AXIS CENTERED ALONG FROM A 1008 MB LOW NEAR 15N106W TO 10N117W TO 10N125W TO A 1011 MB LOW NEAR 12N135W TO 11N140W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF LOW NEAR 12N135W. ...DISCUSSION... LARGE SCALE FEATURES WILL REMAIN IN A REX BLOCKED PATTERN THROUGH NEXT 48 HOURS AS MAIN ENERGY FOCUS STAYS N OF THE REGION. AN UPPER LEVEL CYCLONIC CIRCULATION JUST N OF THE FAR NE CORNER OF THE AREA OVER SOUTHERN CALIFORNIA HAS A TROUGH EXTENDING SW TO 27N125W TO NEAR 22N127W. THE CIRCULATION IS BETWEEN AN UPPER RIDGE OVER THE CENTRAL U.S. EXTENDING SW TO AN UPPER ANTICYCLONE NEAR 18N115W AND A RATHER EXTENSIVE MID/UPPER LEVEL RIDGE THAT STRETCHED FROM A SMALL MID/UPPER LEVEL ANTICYCLONE NEAR 22N137W NE TO WELL N OF THE REGION AT 32N133W REACHING TO THE FAR NE PACIFIC TO JUST W OF THE NW U.S. COAST. A WEAK 1018 SURFACE HIGH IS NEAR 31N135W...WITH WEAK HIGH PRES NOTED N OF 21NW OF 126W. A RATHER LARGE UPPER TROUGH WAS APPROACHING THE NW CORNER OF THE REGION...WHILE ITS ASSOCIATED SURFACE COLD FRONT IS ABOUT 400 NM W OF 32N140W. A JET STREAM BRANCH AHEAD OF THE TROUGH IS DEPICTED BY SW WINDS OF 40-80 KT IN SATELLITE DERIVED WINDS. SATELLITE WATER VAPOR IMAGERY SHOWS MODERATE SUBSIDENCE ALLOWING FOR LIMITED DEEP ATMOSPHERIC MOISTURE OVER MOST OF THIS PORTION OF THE REGION WITH STABLE ENVIRONMENTAL CONDITIONS AS NOTED BY THE MOSTLY OVERCAST STRATOCUMULUS CLOUD FIELD N OF 18N. ITCZ CONVECTION RELATED TO THE ITCZ AND NEAR THE 1011 MB LOW WAS UNDER A DIFFLUENT FLOW ALOFT LOCATED TO THE SW OF THE ANTICYCLONE NEAR 22N137W. OVER THE FAR EASTERN PORTION OF THE AREA...AN UPPER TROUGH EXTENDS FROM EASTERN U.S. SW TO THE WESTERN GULF OF MEXICO TO ACROSS CENTRAL MEXICO SW TO THE SURFACE LOW NEAR 15N106W. THE LOW IS ON THE FAR WESTERN EDGE OF A NOW DIMINISHED MONSOON GYRE THAT HAS PERSISTED ACROSS THE FAR EPAC...SRN MEXICO...AND CENTRAL AMERICA DURING THE PAST SEVERAL DAYS. N TO NE UPPER WINDS BEHIND THE TROUGH ARE CREATING ENOUGH VERTICAL SHEAR TO HAMPER ANY DEEP CONVECTION THAT FORMS WITH THE LOW FROM ACHIEVING ANY LONGEVITY THROUGH THE NEXT 48 HOURS. WINDS OF 20 KT WITHIN 120 NM OF THE LOW CENTER ARE FORECAST TO DIMINISH TO WITHIN 90 NM OF THE LOW IN 24 HOURS...AND TO WITHIN 120 NM OF THE LOW IN THE SEMICIRCLE IN 48 HOURS. THE LOW IS FORECAST TO DRIFT TO SE OVER THE NEXT 48 HOURS. THE WEAKENED MONSOON FLOW IN THE EASTERN SECTION OF THE AREA IS IDENTIFIED AS SW 20 WINDS FROM 3N TO 6N BETWEEN 80W AND 85W WITH SEAS OF 8 FT. THIS AREA IS FORECAST TO EXPAND IN 48 HOURS FROM 5N TO 10N BETWEEN 80W AND 90W WITH SEAS OF 8 FT. S OF THE MONSOON FLOW...CROSS-EQUATORIAL SE TO S 15 KT WINDS ARE OCCURRING ARE NOTED. N WINDS OF 20 TO 25 KT ARE OBSERVED THROUGH THE ISTHMUS OF TEHUANTEPEC WITH TO 9 FT. WITH RIDGING BUILDING SOUTHEASTWARD ACROSS MEXICO THROUGH THE NEXT 24 TO 48 HOURS...THESE WINDS SHOULD MAXIMIZE UP TO 30 KT WITH SEAS BUILDING TO THE RANGE OF 8 TO 11 FT. WINDS MAY STAY JUST BELOW 30 KT IF NOT ENOUGH MIXING OF COLD HIGH PRES AIR TO THE SURFACE IS REALIZED. ELSEWHERE...SUBSIDING NW SWELLS OF 9 FT OVER THE NW SECTION OF THE REGION WILL BE REPLENISHED BY A LARGE NW SWELL TRAIN BEGINNING IN ABOUT 24 HOURS IN THE WAKE OF A WEAKENING FRONT THAT BEGINS TO NEAR THE NW CORNER. LATEST WAVEWATCH MODEL GUIDANCE BUILDS SEAS IN THE 8 TO 10 FT RANGE NW OF A LINE FROM 30N120W TO 10N130W TO 10N140W IN 24 HOURS...AND TO 11 FT N OF 20N W OF 118W IN 48 HOURS WITH HIGHEST SEAS IN THE NW PART AS HIGH PRES RIDGING BUILDS ESE ACROSS THE NORTHERN AND NW PORTIONS AS COLD FRONT DISSIPATES IN THE FAR NW CORNER. THESE SWELLS ARE FORECAST TO HAVE PERIODS OF 15-18 SECONDS TODAY...DIMINISHING TO 11-13 FT SAT AND TO 9-12 FT SUN. $$ AGUIRRE 000 AXPZ20 KNHC 011600 RRA TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC FRI OCT 01 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 1545 UTC. ...ITCZ... AXIS CENTERED ALONG FROM A 1008 MB LOW NEAR 15N106W TO 10N117W TO 10N125W TO A 1011 MB LOW NEAR 12N135W TO 11N140W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF LOW NEAR 12N135W. ...DISCUSSION... LARGE SCALE FEATURES WILL REMAIN IN A REX BLOCKED PATTERN THROUGH NEXT 48 HOURS AS MAIN ENERGY FOCUS STAYS N OF THE REGION. AN UPPER LEVEL CYCLONIC CIRCULATION JUST N OF THE FAR NE CORNER OF THE AREA OVER SOUTHERN CALIFORNIA HAS A TROUGH EXTENDING SW TO 27N125W TO NEAR 22N127W. THE CIRCULATION IS BETWEEN AN UPPER RIDGE OVER THE CENTRAL U.S. EXTENDING SW TO AN UPPER ANTICYCLONE NEAR 18N115W AND A RATHER EXTENSIVE MID/UPPER LEVEL RIDGE THAT STRETCHED FROM A SMALL MID/UPPER LEVEL ANTICYCLONE NEAR 22N137W NE TO WELL N OF THE REGION AT 32N133W REACHING TO THE FAR NE PACIFIC TO JUST W OF THE NW U.S. COAST. A WEAK 1018 SURFACE HIGH IS NEAR 31N135W...WITH WEAK HIGH PRES NOTED N OF 21NW OF 126W. A RATHER LARGE UPPER TROUGH WAS APPROACHING THE NW CORNER OF THE REGION...WHILE ITS ASSOCIATED SURFACE COLD FRONT IS ABOUT 400 NM W OF 32N140W. A JET STREAM BRANCH AHEAD OF THE TROUGH IS DEPICTED BY SW WINDS OF 40-80 KT IN SATELLITE DERIVED WINDS. SATELLITE WATER VAPOR IMAGERY SHOWS MODERATE SUBSIDENCE ALLOWING FOR LIMITED DEEP ATMOSPHERIC MOISTURE OVER MOST OF THIS PORTION OF THE REGION WITH STABLE ENVIRONMENTAL CONDITIONS AS NOTED BY THE MOSTLY OVERCAST STRATOCUMULUS CLOUD FIELD N OF 18N. ITCZ CONVECTION RELATED TO THE ITCZ AND NEAR THE 1011 MB LOW WAS UNDER A DIFFLUENT FLOW ALOFT LOCATED TO THE SW OF THE ANTICYCLONE NEAR 22N137W. OVER THE FAR EASTERN PORTION OF THE AREA...AN UPPER TROUGH EXTENDS FROM EASTERN U.S. SW TO THE WESTERN GULF OF MEXICO TO ACROSS CENTRAL MEXICO SW TO THE SURFACE LOW NEAR 15N106W. THE LOW IS ON THE FAR WESTERN EDGE OF A NOW DIMINISHED MONSOON GYRE THAT HAS PERSISTED ACROSS THE FAR EPAC...SRN MEXICO...AND CENTRAL AMERICA DURING THE PAST SEVERAL DAYS. N TO NE UPPER WINDS BEHIND THE TROUGH ARE CREATING ENOUGH VERTICAL SHEAR TO HAMPER ANY DEEP CONVECTION THAT FORMS WITH THE LOW FROM ACHIEVING ANY LONGEVITY THROUGH THE NEXT 48 HOURS. WINDS OF 20 KT WITHIN 120 NM OF THE LOW CENTER ARE FORECAST TO DIMINISH TO WITHIN 90 NM OF THE LOW IN 24 HOURS...AND TO WITHIN 120 NM OF THE LOW IN THE SEMICIRCLE IN 48 HOURS. THE LOW IS FORECAST TO DRIFT TO SE OVER THE NEXT 48 HOURS. THE WEAKENED MONSOON FLOW IN THE EASTERN SECTION OF THE AREA IS IDENTIFIED AS SW 20 WINDS FROM 3N TO 6N BETWEEN 80W AND 85W WITH SEAS OF 8 FT. THIS AREA IS FORECAST TO EXPAND IN 48 HOURS FROM 5N TO 10N BETWEEN 80W AND 90W WITH SEAS OF 8 FT. S OF THE MONSOON FLOW...CROSS-EQUATORIAL SE TO S 15 KT WINDS ARE OCCURRING ARE NOTED. N WINDS OF 20 TO 25 KT ARE OBSERVED THROUGH THE ISTHMUS OF TEHUANTEPEC WITH TO 9 FT. WITH RIDGING BUILDING SOUTHEASTWARD ACROSS MEXICO THROUGH THE NEXT 24 TO 48 HOURS...THESE WINDS SHOULD MAXIMIZE UP TO 30 KT WITH SEAS BUILDING TO THE RANGE OF 8 TO 11 FT. WINDS MAY STAY JUST BELOW 30 KT IF NOT ENOUGH MIXING OF COLD HIGH PRES AIR TO THE SURFACE IS REALIZED. ELSEWHERE...SUBSIDING NW SWELLS OF 9 FT OVER THE NW SECTION OF THE REGION WILL BE REPLENISHED BY A LARGE NW SWELL TRAIN BEGINNING IN ABOUT 24 HOURS IN THE WAKE OF A WEAKENING FRONT THAT BEGINS TO NEAR THE NW CORNER. LATEST WAVEWATCH MODEL GUIDANCE BUILDS SEAS IN THE 8 TO 10 FT RANGE NW OF A LINE FROM 30N120W TO 10N130W TO 10N140W IN 24 HOURS...AND TO 11 FT N OF 20N W OF 118W IN 48 HOURS WITH HIGHEST SEAS IN THE NW PART AS HIGH PRES RIDGING BUILDS ESE ACROSS THE NORTHERN AND NW PORTIONS AS COLD FRONT DISSIPATES IN THE FAR NW CORNER. THESE SWELLS ARE FORECAST TO HAVE PERIODS OF 15-18 SECONDS TODAY...DIMINISHING TO 11-13 FT SAT AND TO 9-12 FT SUN. $$ AGUIRRE