000 AXPZ20 KNHC 112202 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC FRI SEP 11 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC. ...SPECIAL FEATURE... TROPICAL STORM LINDA CENTERED NEAR 20.7N 131.3W AT 11/2100 UTC MOVING NW OR 310 DEG AT 5 KT. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB. LATEST BOTH VISIBLE AND INFRARED SATELLITE IMAGERY SHOWS THAT LINDA HAS BEEN REDUCED TO A VERY PRONOUNCED CIRCULATION...REMNANT LOW...VOID OF ANY DEEP CONVECTION UNDER DEEP SOUTHERLY SHEAR. THE CIRCULATION CONSISTS OF BROKEN LOW CLOUDS WITH SOME PATCHES OF OVERCAST LOW AND MID CLOUDS WITH WIDELY SCATTERED SHOWERS MOST PROBABLE WITHIN 180 NM OF THE CENTER IN THE NRN SEMICIRCLE. THE SLY SHEAR IS ALLOWING FOR SCATTERED TO BROKEN MID AND HIGH CLOUDS TO STREAM NEWD WELL N OF THE CENTER IN THE GENERAL DIRECTION OF CALIFORNIA. LINDA WILL MOST LIKELY BE DOWNGRADED TO A TROPICAL DEPRESSION THIS EVENING. LATEST NHC FORECAST HAS LINDA BECOMING A REMNANT LOW THEREAFTER THROUGH THE NEXT COUPLE OF DAYS. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP5/ WTPZ25 KNHC...AND PUBLIC ADVISORY UNDER TCPEP5/ WTPZ35 KNHC FOR MORE DETAILS. ...TROPICAL WAVE... A TROPICAL WAVE IS ANALYZED NEAR 101W FROM 5N-15N MOVING W AT ABOUT 17 KT. LATEST SATELLITE IMAGERY SHOWS THAT THE WEAK MID-LEVEL CYCLONIC CIRCULATION NOTED EARLIER ON THE WAVE AXIS HAS SINCE BEEN ILL-DEFINED. SMALL CLUSTERS OF SCATTERED MODERATE CONVECTION ARE ALONG THE WAVE AXIS FROM 7N-10N. A FEW SHOWERS AND ISOLATED TSTMS ARE WITHIN 60-90 NM W OF THE NRN PORTION OF THE WAVE FROM 13N-15N. DEEP CONVECTION HAS BEEN SHORT-LIVED WITH THIS WAVE DUE TO STRONG UPPER LEVEL ELY SHEAR ACROSS THIS PORTION OF THE REGION. ONLY ISOLATED SHOWERS AND WEAK SMALL TSTMS ARE SEEN ELSEWHERE WITHIN 180 NM EITHER SIDE OF THE WAVE. ...THE ITCZ... ITCZ AXIS IS ALONG 9N85W TO 11N100W TO 7N120W TO 06N130W TO 6N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 180 NM S OF THE AXIS BETWEEN 85W-88W. ...DISCUSSION... AN UPPER LEVEL CYCLONE WELL N OF THE AREA NEAR 35N127W HAS AN ASSOCIATED TROUGH EXTENDING SW THROUGH 32N132W TO SW OF THE AREA NEAR 24N140W. TO THE E OF THIS TROUGH MODERATE TO STRONG SLY WINDS...THE SAME IMPACTING LINDA...CONTINUE TO ADVECT DRY AND STABLE CONDITIONS INTO THE FAR WESTERN PORTION OF THE AREA NOTED AS MODERATE SUBSIDENCE IN THE WATER VAPOR IMAGERY. A NEARLY STATIONARY UPPER ANTICYCLONE IS NEAR 22N115W WITH A RIDGE EXTENDING SW ACROSS LINDA AND FURTHER SW TO NEAR 12N140W. ANOTHER RIDGE EXTENDS E-SE FROM THE ANTICYCLONE TO ALONG THE MEXICAN COAST TO THE FAR WESTERN SECTION OF THE GULF OF TEHUANTEPEC. THE SURFACE RIDGE EXTENDS SE FROM A 1022 MB HIGH NEAR 32N139W TO 26N126W...AND TO NEAR 21N118W. A DEEP MOISTURE PLUME ORIGINATING FROM BOTH ITCZ CONVECTION...AND CONVECTION EARLIER OVER MEXICO...IS BEING ADVECTED WESTWARD OVER THE SRN PERIPHERY OF THE RIDGE TO NEAR 126W WHERE IT ERODES IN THE DRIER AIR. LEFTOVER DEBRIS MOSITURE...IN THE FORM OF MID AND HIGH CLOUDINESS...FROM LINDA IS BEING CHANNELED NORTHEASTWARD AND THEN E AND SE AROUND THE NORTHERN CREST OF THE ANTICYCLONE TOWARDS BAJA CALIFORNIA AND NORTHWESTERN MEXICO. A WEAKENING UPPER LEVEL LOW LOCATED OVER THE SW CARIBBEAN SEA JUST E OF NICARAGUA IS ENHANCING SCATTERED STRONG CONVECTION OVER AND ALONG THE CENTRAL AMERICAN COASTLINE FROM COSTA RICA TO EL SALVADOR. LATEST UPPER AIR MODEL GUIDANCE SUGGESTS THAT THE LOW WILL MOVE W AND SW ACROSS THE FAR EASTERN PORTION OF THE REGION THROUGH SAT NIGHT WHILE WEAKENING. A TIGHT PRES GRADIENT CONTINUES IN EXISTENCE BETWEEN TROPICAL STORM LINDA AND RIDGING TO ITS N. THIS IS BRINGING NE WINDS OF 20-33 KT ELSEWHERE WITHIN 300 NM NW AND 150 NM SE SEMICIRCLES OF LINDA WITH SEAS UP TO 11 FT. HOWEVER...THESE CONDITIONS WILL GRADUALLY SUBSIDE THROUGH THE NEXT 48 HOURS AS LINDA WEAKENS FURTHER. A QUIKSCAT PASS FROM THIS MORNING REVEALED AN EXTENSIVE SWATH OF S-SW WINDS OF 20 KT S OF ABOUT 8N AND E OF 114W. SEVERAL RAIN-FLAGGED WINDS VECTORS OF 20-30 KT WHERE NOTED IN ITCZ CONVECTION BETWEEN 85W-88W. A SHIP WITH CALLER ID "A8RL5" NEAR 8N90.5W REPORTED S WINDS VERY CLOSE TO 30 KT AT 1815 UTC WITH COMBINED SEAS OF 12 FT. THESE WIND SPEEDS ARE MOST ATTRIBUTED TO POSSIBLE OUTFLOW FROM NEARBY ITCZ CONVECTION. CURRENT FORECAST CALLS FOR S WINDS OF 20 KT TO BE CONFINED TO S OF 9N BETWEEN 88W-118W OVER THE NEXT 48 HOURS. A DEEP LAYER TROUGH NW OF THE REGION MOVING RAPIDLY SE TOWARDS THE FAR NW CORNER IS CONSISTENTLY BEING FORECAST BY NWP MODELS TO PUSH A COLD FRONT INTO THE NW PORTION OF THE AREA DURING THE WEEKEND BRINGING LARGE LONG PERIOD NWLY SWELLS MAXING UP TO 10 OF 11 FT PER LATEST WAVE MODEL GUIDANCE. THESE SWELLS SHOULD OVERSPREAD ACROSS THE NW PART OF THE AREA THROUGH THE WEEKEND AS THE FRONT WEAKENS OVER THE FAR NORTHERN SECTION. CROSS EQUATORIAL SLY WINDS OF 20 KT AND SWELLS GENERATED BY A BROAD FIELD OF SE WINDS 20-25 KT S OF THE EQUATOR WILL CONTINUE TO AFFECT THE FAR SOUTHERN PORTION S OF 7N BETWEEN 85W-114W AND TO S OF 8N BETWEEN 97W-118W WITHIN 48 HOURS. $$ AGUIRRE