000 AXPZ20 KNHC 151534 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SAT SEP 15 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 1415 UTC. ...SPECIAL FEATURES... TROPICAL STORM KRISTY IS CENTERED NEAR 22.4N 115.0W AT 1500 UTC MOVING NW OR 315 DEG AT 8 KT. MAXIMUM SUSTAINED WINDS ARE 35 KT WITH GUSTS TO 45 KT AND MINIMUM PRESSURE IS 1002 MB. KRISTY IS WEAKENING UNDER SOUTHWESTERLY SHEAR AS IT MOVES INTO SEA SURFACE TEMPERATURE OF 25 DEGREES CELSIUS OR LESS. IT WILL BE HARD FOR KRISTY TO MAINTAIN CONVECTION MUCH LONGER WITH SUCH A COOL OCEAN BENEATH. SCATTERED MODERATE CONVECTION CURRENTLY LIES WITHIN 150 NM NE AND 30 NM SW SEMICIRCLES OF CENTER. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS. NEWLY FORMED TROPICAL DEPRESSION TWELVE IS CENTERED NEAR 14.0N 123.5W AT 1500 UTC MOVING W OR 270 DEG AT 5 KT. MAXIMUM SUSTAINED WINDS ARE 30 KT WITH GUSTS TO 40 KT AND MINIMUM PRESSURE IS 1003 MB. MICROWAVE DATA SHOWS THAT THIS AREA OF DISTURBED WEATHER NOW HAS A WELL DEFINED LOW LEVEL CENTER. THE DEPRESSION IS EXPECTED TO INTENSIFY TO A TROPICAL STORM BY THIS EVENING AS THE NORTHERLY SHEAR OVER THE SYSTEM ABATES. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ42 KNHC FOR MORE DETAILS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS WAS ANALYZED FROM 08N78W TO 08N104W TO 09N115W TO 08N119W THEN CONTINUES FROM 12N124W TO 11N126W TO LOW PRES NEAR 13N134W TO 12N135W. THE ITCZ AXIS WAS ANALYZED FROM 12N135W TO 11N140W. SCATTERED MODERATE CONVECTION WAS S OF THE AXIS TO 04N E OF 80W...WITHIN 150 NM N OF THE AXIS BETWEEN 85W AND 88W...WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 98W AND 103W...WITHIN 330 NM N AND 240 NM S OF THE AXIS BETWEEN 103W AND 108W...AND WITHIN 120 NM N AND 300 NM S OF THE AXIS BETWEEN 113W AND 119W. SCATTERED MODERATE CONVECTION WAS ALSO WITHIN 120 NM NE AND 75 NM NW QUADRANTS OF THE LOW PRES SYSTEM NEAR 13N134W. ...DISCUSSION... THE PATTERN ALOFT FEATURES A RIDGE AXIS THAN EXTENDS SOUTHWESTWARD FROM AN ANTICYCLONE CENTERED N OF THE AREA NEAR 27N126W THROUGH 16N130W TO 12N140W. DRY AIR AND IMPLIED SUBSIDENCE OCCUPIES MUCH OF THE AREA N OF 16N BETWEEN 118W AND 128W...PRIMARILY SE OF THE ANTICYCLONE. CONVECTION IS BEING ENHANCED BY THIS RIDGE AXIS NEAR THE SURFACE LOW PRES SYSTEM EMBEDDED IN THE MONSOON TROUGH AND DESCRIBED IN THE SECTION ABOVE. FARTHER E...AN UPPER LOW NEAR 22N115W LIES NEAR TROPICAL STORM KRISTY AND A SHARP MID-LATITUDE TROUGH EXTENDS SOUTHWESTWARD THROUGH NORTHEASTERN MEXICO AND THE CENTRAL GULF OF CALIFORNIA TOWARD THIS UPPER LOW. SOUTHWESTERLY SHEAR ON THE LEADING EDGE OF THE TROUGH AND LOW LIE OVER KRISTY AND ARE HELPING TO WEAKEN IT. MID LEVEL MOSITURE FROM KRISTY IS BEING PUMPED INTO THE LEADING EDGE OF THE MID LATITUDE TROUGH. SCATTERED MODERATE CONVECTION IS NOTED OVER THE GULF OF CALIFORNIA FROM 25N TO 29N WHERE THIS MOSITURE IS PLENTIFUL. ANOTHER ANTICYCLONE LIES NEAR CABO CORRIENTES...MEXICO AND EXTENDS A RIDGE SOUTHWESTWARD TO 06N120W. THE RIDGE AXIS IS LIFTING THE LOW LEVEL MOSITURE POOLED ALONG THE MONSOON TROUGH BETWEEN 110W AND 120W. THIS CONVECTION IS DESCRIBED IN THE SECTION ABOVE. IT IS LARGELY SKEWED S OF THE MONSOON TROUGH BY 30-40 KT N-NE WINDS ALOFT. THIS NORTH-NORTHEASTERLY UPPER JET EXTENDS OVER MUCH OF THE AREA S OF 06N BETWEEN 110W AND 130W. E OF 100W...HIGH PRES OVER THE WESTERN GULF OF MEXICO IS DRIVING NORTHERLY WINDS THROUGH CHIVELA PASS TOWARD LOWER PRES ASSOCIATED WITH THE MONSOON TROUGH TO THE S. THE 0550 UTC ASCAT PASS SHOWS FRESH TO STRONG N-NE WINDS ARE FUNNELING THROUGH THE GULF OF TEHUANTEPEC AS A RESULT...WITH SEAS IN THE 6-9 FT RANGE EXTENDING AS FAR AS 450 NM DOWNWIND OF TEHAUNTEPEC ACCORDING TO THE 0310 UTC JASON1 PASS. THIS PRES GRADIENT IS ALSO DRIVING FRESH NE WINDS THROUGH THE GULF OF PAPAGAYO...WITH WINDS PULSING TO A STRONG BREEZE IN THE EARLY MORNING HOURS WITH THE ASSISTANCE OF DRAINAGE FLOW OFF THE LAND. THE PRES GRADIENT IS EXPECTED TO RELAX BY LATE SUN MORNING AS THE RIDGING IN THE WESTERN GULF OF MEXICO BREAKS DOWN. $$ SCHAUER