000 AXPZ20 KNHC 230946 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC WED SEP 23 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0730 UTC. ...SPECIAL FEATURE... TROPICAL STORM NORA IS NEAR 16.1N 116.7W AT 23/0900 UTC MOVING NW OR 310 DEG AT 7 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC FOR MORE DETAILS. AN INCREASINGLY MORE ORGANIZED BAND OF CONVECTION EXTENDED W AND THEN N FROM NEAR THE CENTER OF NORA BEFORE THE GOES-11 ECLIPSE PERIOD BEGAN AT 0730 UTC WITH SCATTERED MODERATE AND ISOLATED STRONG CONVECTION FOUND WITHIN 180 NM W SEMICIRCLE. NORA IS FORECAST TO TRACK NW FOR THE NEXT 24 HOURS AND INTENSIFY TO 50 KT BEFORE FORGING A MORE WESTERLY TRACK AND WEAKENING AS IT MOVES UNDER STRONG SW VERTICAL WIND SHEAR AND BECOMES SURROUNDED BY A RATHER STABLE ENVIRONMENT. ...THE ITCZ... THE INTERTROPICAL CONVERGENCE ZONE IS ALONG 09N79W TO 08N100W TO 14N116W TO 10N125W TO 08N140W. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 75 NM S OF THE ITCZ AXIS BETWEEN 81W AND 83W AND WITHIN 75 NM N OF THE ITCZ AXIS BETWEEN 85W AND 87W. SCATTERED MODERATE CONVECTION LIES WITHIN 90 NM N OF THE ITCZ AXIS BETWEEN 121W AND 124W AND WITHIN 90 NM S OF THE ITCZ AXIS BETWEEN 124W AND 126W. ...DISCUSSION... N OF 20N... WEAK HIGH PRES AND MOSTLY BROKEN STRATOCUMULUS WILL PERSIST OVER N WATERS THROUGH THE PERIOD WITH CIRRUS OVER W WATERS ALONG THE SOUTH EDGE OF A 50 KT WESTERLY JET FROM 22N140W TO 22N120W TO 26N110W. THIS JET IS ON THE SOUTH SIDE OF THE POSITIVELY TILTED UPPER TROUGH OVER THE SOUTHWEST U.S. AND NW MEXICO. THE UPPER TROUGH AND JET AXIS ARE EXPECTED TO REMAIN STATIONARY THE NEXT FEW DAYS. THE COLD FRONT ASSOCIATED WITH THIS TROUGH HAS MOVED S INTO NORTHERN MEXICO WITH LITTLE FANFARE OVER THE NORTHERN GULF OF CALIFORNIA. WINDS ONLY INCREASED TO 15 KT BEHIND THE FRONT AS IT PASSED THROUGH YUMA AZ AND BLYTHE CA TUE EVENING AND THERE WERE A MERE 2 WIND BARBS N OF 31N FROM THE 0214 UTC QUIKSCAT PASS THAT SHOWED WINDS OVER 20 KT. THE MODELS CONTINUE TO SHOW WINDS INCREASING TO 20-25 KT OVER THE NORTHERN GULF OF CALIFORNIA LATER TODAY AS A SECONDARY WIND SURGE PASSES S INTO NW MEXICO. THE IMPETUS SHORTWAVE ENERGY ASSOCIATED WITH THIS SURGE IS CLEARLY VISIBLE OVER SE ARIZONA/SW NEW MEXICO ON INFRARED IMAGERY. HOWEVER...SURFACE OBSERVATIONS CURRENTLY SHOW WINDS SHIFTING MORE NORTHEASTERLY BEHIND IT OVER CENTRAL ARIZONA. THIS SHOULD HOLD TRUE AS THE WIND SURGE MAKES IT INTO MEXICO WHERE THE HIGH TERRAIN E OF THE GULF OF CALIFORNIA SHOULD BLOCK MUCH OF THIS NE FLOW FROM REACHING THE GULF. THEREFORE...THE FORECAST DOES NOT CALL FOR WINDS TO INCREASE OVER 20 KT FOR ANY SUBSTANTIAL AMOUNT OF TIME OR AREA OVER THE GULF OF CALIFORNIA. THE REMNANTS OF FORMER TROPICAL STORM MARTY HAVE DEGRADED TO A TROUGH ALONG 133W FROM 20N TO 27N MOVING W ABOUT 10 KT. WINDS BETWEEN THE TROUGH AND THE RIDGE AXIS EXTENDING SE FROM 1011 MB HIGH PRES NEAR 31N132W TO 25N124W ARE STILL TO 20 KT. THIS AREA OF WINDS IS EXPECTED TO MIGRATE SW AS THE RIDGE AXIS SWEEPS SOUTHWESTWARD AND THE WEAKENING TROUGH APPROACHES 140W. A COLD FRONT NEARING THE NW CORNER OF THE AREA IN ASSOCIATION WITH A DEEP LAYER TROUGH IS EXPECTED TO STALL AND WEAKEN N OF THE AREA THROUGH THE NEXT 36 HOURS AS THE RIDGE HOLDS FIRM ACROSS NORTH WATERS. S OF 20N... SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION LIES WITHIN 270 NM W OF A TROUGH AXIS ALONG 133W FROM 07N TO 13N. THIS TROUGH IS CAUSING A WEAK PERTURBATION ALONG THE ITCZ. WINDS TO 20 KT NEAR THE TROUGH ARE EXPECTED TO EXPAND IN AREA AS THE RIDGE AXIS TO THE NORTH SWEEPS SOUTHWEST..INCREASING THE PRES GRADIENT. A WELL PRONOUNCED MID/UPPER ANTICYCLONE CENTERED OVER INLAND MEXICO NEAR 22N100W EXTENDS A RIDGE SW TO OVER TROPICAL STORM NORA...AND TO NEAR 16N120W. TO THE S OF THE RIDGE...A BROADLY DIFFLUENT UPPER LEVEL PATTERN IS NOTED WITH SCATTERED MODERATE CONVECTION NEAR THE COAST OF CENTRAL AMERICA FROM COSTA RICA TO GUATEMALA. GAP WINDS... THE COLD FRONT PASSING SOUTH THROUGH EASTERN MEXICO IS EXPECTED TO BRING 20 KT NORTHERLY FLOW THROUGH THE BAY OF CAMPECHE INTO THE GULF OF TEHUANTEPEC OVERNIGHT TONIGHT AND CONTINUE THROUGH THE FORECAST PERIOD. $$ SCHAUER CLARK