000 AXPZ20 KNHC 161516 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SUN SEP 16 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 1315 UTC. ...SPECIAL FEATURES... TROPICAL STORM LANE CENTERED NEAR 13.8N 125.1W AT 1500 UTC MOVING NW OR 305 DEG AT 7 KT. MAXIMUM SUSTAINED WINDS ARE 55 KT WITH GUSTS TO 65 KT AND A MINIMUM PRESSURE OF 999 MB. SCATTERED MODERATE TO STRONG CONVECTION WAS WITHIN 90 NM E AND 45 NM W SEMICIRCLES OF CENTER WITH SCATTERED MODERATE CONVECTION ELSEWHERE WITHIN 210 NM S QUADRANT. LANE IS GRADUALLY BECOMING BETTER ORGANIZED AND IS FORECAST TO REACH MINIMAL HURRICANE STRENGTH MON MORNING BEFORE MOVING INTO AN ENVIRONMENT OF INCREASING SOUTHWESTERLY SHEAR AND OVER COOLER OCEAN WATERS WHICH SHOULD WEAKEN LANE. SEE THE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC FOR ADDITIONAL DETAILS. TROPICAL STORM KRISTY CENTERED NEAR 24.5N 117.9W AT 1500 UTC MOVING NW OR 305 DEG AT 8 KT. MAXIMUM SUSTAINED WINDS ARE 35 KT WITH GUSTS TO 45 KT AND MINIMUM PRESSURE OF 1004 MB. SCATTERED MODERATE CONVECTION WAS WITHIN 45 NM N AND 120 NM S SEMICIRCLE OF CENTER. KRISTY SHOULD BECOME A DEPRESSION LATER TODAY AS IT REMAINS SEPARATED FROM THE CONVECTION AND CONTINUES TO TRAVERSE SEA SURFACE TEMPERATURES OF 23 DEGREES CELSIUS OR LOWER. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS WAS ANALYZED FROM 10N84W TO 10N105W TO 13N111W THEN CONTINUES FROM 13N130W TO LOW PRES NEAR 12N133W TO 10N135W TO 10N140W. SCATTERED MODERATE TO STRONG CONVECTION WAS WITHIN 90 NM NE AND 120 NM SW SEMICIRCLES OF THE LOW PRES CENTER. ISOLATED MODERATE TO STRONG CONVECTION WAS WITHIN 300 NM N AND 330 NM S OF THE AXIS BETWEEN 90W AND 105W. ...DISCUSSION... THE PATTERN ALOFT FEATURES A TROUGH AXIS THAT EXTENDS SOUTHWARD FROM AN UPPER LOW N OF THE AREA NEAR 34N138W TO 20N140W AND AN ANTICYCLONE NEAR 29N122W TO 11N140W. CONVERGENCE BETWEEN THE TROUGH AND RIDGE AXIS IS PROVIDING A SOUTHERLY STREAM OF MID TO UPPER LEVEL MOISTURE EVIDENT IN WATER VAPOR IMAGERY. DRY CONDITIONS ALOFT AND IMPLIED SUBSIDENCE CAN BE FOUND FROM 19N TO 26N BETWEEN 121W AND 130W AS WELL AS N OF 26N W OF 127W INTO NE MEXICO TO THE TROUGH AXIS THAT EXTENDS FROM THE TEXAS BIG BEND THROUGH THE SOUTHERN GULF OF CALIFORNIA. THIS TROUGH AXIS CONTINUES SOUTHWESTWARD THROUGH A WEAK UPPER LOW NEAR 20N123W TO A SECOND UPPER LOW AT 14N123W NEAR T.S. LANE. THE TROUGH AXIS LIES JUST S OF T.S. KRISTY AND MOISTURE FROM KRISTY IS STREAMING NORTHEASTWARD ALONG THE TROUGH AXIS INTO MEXICO. MEANWHILE...THE NORTHERLY SHEAR CURRENTLY OVER T.S. LANE IS ATTRIBUTABLE TO THE SOUTHERN MOST UPPER LOW ON THE TROUGH. THE UPPER TROUGH IS EXPECTED TO SHIFT W AWAY FROM T.S. LANE OVER THE 24 HOURS...MAKING CONDITIONS FAVORABLE FOR LANE TO BRIEFLY INTENSIFY TO HURRICANE STRENGTH. TO THE W OF T.S. LANE LIES A SURFACE LOW EMBEDDED IN THE MONSOON TROUGH NEAR 12N133W. SCATTERED MODERATE TO STRONG CONVECTION WAS WITHIN 90 NM NE AND 120 NM SW SEMICIRCLES OF THIS LOW PRES SYSTEM. THE NUMERICAL GUIDANCE HAS BEEN TRYING TO DISSIPATE THIS LOW...ALLOWING IT TO BECOME CAPTURED IN THE LARGER CIRCULATION OF T.S. LANE TO ITS E. HOWEVER...THE LOW APPEARS TO BE MORE PERSISTENT THAN THE MODELS HAVE SUGGESTED AND HAS A LARGER WIND FIELD THAN THE OVERNIGHT MODEL RUNS SHOW WHEN COMPARED TO THE 0816 UTC OSCAT AND 0646 UTC ASCAT PASSES. THIS LOW IS STILL EXPECTED TO BE NEGATIVELY IMPACTED BY THE CIRCULATION AROUND T.S. LANE...BUT THAT MAY TAKE A LITTLE LONGER THAN ADVERTISED. THE CURRENT FORECAST KEEPS THE LOW...AND FRESH TO STRONG WINDS WITH IT...AROUND INTO MON. FARTHER E...STRONG UPPER DIFFLUENCE BETWEEN A LOW ALOFT OVER THE S CENTRAL CARIBBEAN AND AN ANTICYCLONE OVER THE GULF OF HONDURAS NEAR 17N86W IS ENHANCING THE SCATTERED MODERATE TO STRONG CONVECTION FOUND S OF THE GULF OF PANAMA FROM 03N TO 08N E OF 80W TO OVER WESTERN COLOMBIA. FREQUENT LIGHTNING WAS OBSERVED HERE. THIS SHOULD REMAIN A FAVORED REGION FOR CONVECTION THE NEXT FEW DAYS. GAP WINDS...HIGH PRES OVER THE FAR WESTERN GULF OF MEXICO THAT WAS DRIVING NORTHERLY WINDS THROUGH CHIVELA PASS TOWARD LOWER PRES ASSOCIATED WITH THE MONSOON TROUGH TO THE S IS BREAKING DOWN. WHILE THE 0324 UTC ASCAT AND 0636 OSCAT PASSES SHOWED FRESH TO STRONG N-NE WINDS WITHIN 120 NM S-SW OF THE GULF OF TEHUANTEPEC...WINDS ARE DOWN TO 10 KT AT IXTEPEC...MEXICO AND THE PEAK MORNING DRAINAGE FLOW IS OVER. WINDS ARE BELIEVED TO HAVE DIMINISHED BELOW ADVISORY CRITERIA WHILE SEAS SHOULD SUBSIDE BELOW 8 FT BY AFTERNOON. $$ SCHAUER