000 AXPZ20 KNHC 162205 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC. ...SPECIAL FEATURES... TROPICAL STORM LANE CENTERED NEAR 14.4N 125.5W AT 2100 UTC MOVING NW OR 315 DEG AT 7 KT. MAXIMUM SUSTAINED WINDS ARE 55 KT WITH GUSTS TO 66 KT AND A MINIMUM PRESSURE OF 997 MB. LITTLE OVERALL CHANGE WAS NOTED IN THE CLOUD PATTERN OF LANE SO FAR DURING THE DAY. A SMALL CENTRAL DENSE OVERCAST IS SEEN ON LATEST VISIBLE SATELLITE IMAGERY. SCATTERED STRONG CONVECTION IS WITHIN 30 NM OF THE CENTER. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS ELSEWHERE WITHIN 120 NM OF THE CENTER IN THE NE QUADRANT...180 NM OF THE CENTER IN THE SE QUADRANT AND IN AN OUTER BAND WITIN 30 NM OF 13N126W 13N128W. BOTH THE ATMOSPHERIC AND OCEANIC ENVIRONMENTS ARE FAVORABLE FOR LANE TO STRENGTHEN INTO A HURRICANE IN ABOUT 24 HRS NEAR 16.7N 127.4W AS IT TRACKS NW. AFTER 24 HRS AND INTO 48 HRS ...LANE IS FORECAST TO WEAKEN BACK TO A TROPICAL STORM AS MOVES OVER COOLER SEA SURFACE TEMPERATURES. SEE THE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC FOR ADDITIONAL DETAILS. NEWLY DOWNGRADED TROPICAL DEPRESSION KRISTY WAS CENTERED NEAR 25.ON 118.5W AT 2100 UTC MOVING NW OR 315 DEG AT 6 KT WITH MAXIMUM SUSTAINED WINDS OF 30 KT WITH GUSTS TO 40 KT AND MINIMUM PRESSURE OF 1007 MB. LATEST SATELLITE SHOWS A GRADUAL DETERIOATING CLOUD PATTERN WITH THE DEPRESSION...HOWEVER THE CYCLONIC CIRCULATION IS SEEN ON THE E EDGE OF A LARGE AREA OF STRATOCUMLUS CLOUD DECK TO ITS W. CONVECTION HAS WEAKENEDED THROUGOUT THE DAY...AND ONLY SCATTERED MODERATE CONVECTION IS SEEN WITHIN 60 NM NE AND 30 NM SW OF THE CENTER. THE DEPRESSION IS FOECAST TO WEAKENED TO A REMNANT LOW IN ABOUT 24 HRS AS OT MOVES INTO A MORE STABLE ENVIRONMENT AND OVER COOLER SE SURFACE TEMPERATURES. 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 EXTENDS WESTWARD FROM THE SOUTHERN COAST OF COSTA RICA TO 10N95W TO 08N108W TO 12N117W WHERE IT ENDS. IT THEN RESUMES AT 13N128W TO LOW PRES 1010 MB AT 11N132W TO 08N140W. SCATTERED MODERATE TO STRONG CONVECTION IS S OF THE MONSOON TROUGH WITHIN 75 NM OF 06N86W TO 06N81W TO 06N77W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS N OF THE MONSOON TROUGH FROM 10N TO 14N BETWEEN 100W AND 105W. SCATTERED MODERATE CONVECTION IS WITHIN 30 NM OF THE MONSOON TROUGH W OF 137W. ...DISCUSSION... A LONGWAVE UPPER RIDGE CONTINUES OVER MUCH OF THE EASTERN N PACIFIC STEMMING FROM AN UPPER ANTICYCLONE CENTERED AT 29N121W AND RIDGING NE TO WELL BEYOND 35N120W. AN UPPER RIDGE ALSO EXTENDS SW TO A SHARP CREST OVER THE DEEP TROPICS AT 12N139W. A MID/UPPER LAYER TROUGH PERSISTS OVER THE NW PORTION OF THE AREA WITH AN ASSOICATED UPPER CYCLONE JUST NW OF THE AREA. WEAK UPPER DIFFLUENCE IS NOTICED S OF THE TROPICAL UPPER RIDGE OVER THE DEEP TROPICS...AND IS ENHANCING CONVECTION ALONG THE WESTERN SEGMENT OF THE MONSOON TROUGH AND ITS EMBEDDED SURFACE LOW AT 11N133W. SOME OF THE DEBRIS MOISTURE IS ADVECTED N ACROSS THE UPPER RIDGE AXIS BETWEEN 132W AND 144W WHILE IT EVAPORATES. VERY DRY AIR ALOFT DUE TO MODERATE TO STRONG SUBSIDENCE IS OBSERVED NW OF A LINE FROM SRN BAJA CALIFORNIA TO 12N136W. THE UPPER ANTICYCLONE IS EXPECTED TO TURN SE AND REACH THE CENTRAL BAJA PENINSULA ON MON. THE UPPER CYCLONE JUST NW OF THE AREA IS EXPECTED TO CONTINUE LIFTING NE WITH THE UPPER TROUGH EXTENDING S FROM THE CYCLONE SHIFTING SLIGHTLY NW OF THE AREA ON MON...AS THE UPPER JET OVER THE NW PORTION BROADENS TO ABOUT 660 NM WIDE. IMMEDIATELY TO THE E OF THE LARGE UPPER RIDGE IS A DEEP LAYERED CYCLONE OVER NEW MEXICO/TEXAS BORDER...WITH AN UPPER TROUGH EXTENDING SW ACROSS THE CENTRAL BAJA PENINSULA...INTO AN UPPER CYCLONE NEAR TROPICAL CYCLONE KRISTY...WITH THE UPPER TROUGH STILL CONTINUING SW THROUGH 18N125W...AND THEN WRAPPING AROUND THE WESTERN PERIPHERY OF TROPICAL CYCLONE LANE. AN UPPER ANTICYCLONE IS AT 21N107W AND RIDGING SW TO A CREST OVER TROPICAL CYCLONE LANE. A BROAD INVERTED UPPER TROUGH IS NOTED OVER THE DEEP TROPICAL PACIFIC TO THE S OF 17N BETWEEN 95W AND 110W. AN UPPER ANTICYCLONE IS QUASI STATIONARY OVER THE NW CARIBBEAN AT 16N85W...WITH ITS ENVELOPE OF UPPER ANTICYCLONIC FLOW COVERING THE DISCUSSION AREA N OF 06N BETWEEN 82W AND 95W. THESE FEATURES COMBINE TO SET UP AN AREA OF UPPER DIFFLUENCE OVER CENTRAL AMERICA AND THE TROPICAL PACIFIC BETWEEN 100W AND 120W ENHANCING THE TROPICAL PACIFIC CONVECTION PREVIOUSLY MENTIONED. UPPER DEBRIS MOISTURE IS NOTED TO THE N OF 07N BETWEEN 82W AND 100W...AND S OF 15N BETWEEN 100W AND 130W...WITH VERY DRY UPPER AIR INDICATED TO THE S OF 07N BETWEEN 78W AND 100W EXTENDING N FROM A LARGE UPPER ANTICYCLONE OVER THE NE SOUTH PACIFIC. SOME OF THE DEBRIS MOISTURE FROM TROPICAL CYCLONE KRISTY CONCENTRATES IN A PLUME THAT TURNS NE ACROSS NORTHEASTERN OLD MEXICO...THEN FANS OUT AS IT MERGES WITH ADDITIONAL MOISTURE OVER W TEXAS...ALL SPREADING E ACROSS EASTERN TEXAS AND ACROSS THE SE CONUS AND NOW MOVING OVER THE ATLANTIC OFFSHORE THE CAROLINAS. ELSEWHERE AT THE SURFACE...A BROAD RIDGE COVERS THE AREA N OF 20N W OF 122W. A SURFACE RIDGE ORIENTATED FROM NNW TO SSE OVER THE EASTERN PORTION OF OLD MEXICO CONTINUES TO PRODUCE THE NORTHERLY SURGES AT 20 TO 25 KT INTO...AND JUST DOWNSTREAM...OF THE GULF OF TEHUANTEPEC. THESE DRAINAGE WINDS WILL QUICKLY DIMINISH AFTER SUNRISE TODAY. $$ NELSON