000 AXPZ20 KNHC 181005 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC FRI DEC 18 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 0930 UTC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 45N78W TO 7N90W TO 06N100W TO 6N111W TO 6N125W TO 7N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM N OF THE AXIS BETWEEN 132W-137W... WITHIN 60 NM EITHER SIDE OF THE AXIS BETWEEN 83W-87W...WITHIN 60 NM S OF THE AXIS BETWEEN 80W-83W...AND WITHIN 30 NM EITHER SIDE OF THE AXIS BETWEEN 90W-92W. ...DISCUSSION... THE UPPER PATTERN REMAINS RATHER HIGHLY AMPLIFIED ACROSS THE REGION WITH THE FIRST FEATURE NOTED AS A VERY PRONOUNCED MID/UPPER LEVEL TROUGH EXTENDING FROM THE CENTRAL PORTION OF THE U.S. TO ACROSS NORTHERN MEXICO AND FURTHER SW TO 13N120W. TO THE W OF THE TROUGH...RIDGING DOMINATES THE AREA WITH A MEAN RIDGE AXIS ALONG EXTENDING FROM A SMALL MID/UPPER LEVEL ANTICYCLONE NEAR 9N138W NNE TO 21N137W TO WELL N OF THE AREA AT 30N131W ...AND CONTINUING TO THE PACIFIC NW REGION OF THE U.S. BOTH THE RIDGE AND THE TROUGH AREA FORECAST TO MOVE E OVER THE NEXT 48 HRS AS THE NEXT TROUGH...APPEARING QUITE VIGOROUS ON LATEST WATER VAPOR SATELLITE IMAGERY...SCRAPES THE FAR NW CORNER OF THE AREA BY SAT WITH ASSOCIATED UPPER LEVEL CYCLONIC VORTEX PULLING OFF QUICKLY WELL TO THE NE OF THE AREA. HOWEVER...THE ASSOCIATED COLD FRONT IS FORECAST TO ENTER THE THE NW PORTION BY LATE FRI NIGHT...THEN WEAKEN FROM 30N137W TO 26N140W BY LATE SAT NIGHT AS MAIN UPPER LEVEL ENERGY PULLS TO THE N WITH THE VORTEX. SW WINDS TO 20 KT MAY BE EXPECTED WITHIN 90 NM E OF THE FRONT N OF 29N BY LATE SAT NIGHT WITH LARGE NW SWELLS UP TO 14 FT. WINDS W OF THE FRONT WILL BE LESS THAN 20 KT...BUT LARGE NW SWELLS WILL ALSO BE A PROBLEM THERE AS LATEST WAVEWATCH GUIDANCE IS INDICATING LARGE NW SWELLS OF 11 TO 16 FT BEHIND THE FRONT. WITH THIS TROUGH PUSHING INTO THE AREA...THE DEEP LAYER RIDGE WILL BREAK DOWN CAUSING SURFACE RIDGING TO ALSO WEAKEN SOME. AS A RESULT...NE TO E TRADE WINDS OF 20 TO 25 KT FROM 7N TO 18N W OF 118W WILL DIMINISH FROM E TO W THROUGH SAT. A SURFACE TROUGH EXTENDS FROM 3N118W TO A 1009 MB LOW NEAR 7N116W AND NE TO NEAR 10N114W. THIS SYSTEM IS CURRENTLY STATIONARY...AND NOT EXPECTED TO MOVE MUCH DURING THE NEXT 48 HRS. THERE IS A DECIDED LACK OF DEEP CONVECTION NEAR THIS TROUGH AS THE SOUTHERN STREAM WESTERLY UPPER JET LIES JUST N OF THE LOW ALONG IT. BROKEN TO OVERCAST CIRRUS CLOUDS ASSOCIATED WITH UPPER LEVEL MOISTURE TRANSPORT BY THE JET ARE NOTED CAN BE FOUND N OF THE ITCZ AND TO THE E OF 120W...TURNING NE AROUND THE BASE OF THE ABOVE MENTIONED TROUGH NEAR 117W WHERE THE CLOUDS THEN MAKE A NE TRAJECTORY TOWARDS MEXICO. LATEST IR SATELLITE IMAGERY SHOWED SCATTERED MODERATE CONVECTION N OF THE LOW WITHIN 30 NM OF 8N116W. UPPER MODEL WIND FIELD GUIDANCE SUGGESTS THAT THE SOUTHERN STREAM JET STREAM WILL SHIFT MOVE SE AS IT STRETCHES INTO THE LEADING EDGE OF THE TROUGH. STRONG WLYY AND THEN NWLY UPPER WINDS WILL MOVE OVER THE LOW FURTHER INHIBITING DEEP CONVECTION FRI AND ESPECIALLY SAT WHEN THE SURFACE LOW IS EXPECTED TO WEAKEN. 20 KT WINDS ARE CURRENTLY INDICATED WITHIN 120 NM E SEMICIRCLE OF THE LOW WITH SEAS 8 TO 10 FT IN NE SWELL. THESE WINDS ARE FORECAST TO DIMINISH THROUGH THE NEXT 48 HRS AS THE PRES GRADIENT BETWEEN IT AND THE WEAKENING HIGH PRES TO THE N SLACKENS....BUT SEAS MAY REMAIN HIGH AS 8 TO 10 FT IN NW SWELL NEAR THE THE LOW. OVER THE FAR EASTERN SECTION...A HIGH RESOLUTION ASCAT PASS FROM AROUND 0420 UTC SHOWED A BROKEN SWATH OF NW 20 KT OVER THE GULF OF CALIFORNIA FROM 25N TO ABOUT 28N. THESE WINDS ARE EXPECTED TO SHIFT SLIGHTLY N THROUGH LATE SAT NIGHT AS HIGH PRES WEAKENS OVER EASTERN MEXICO...BUT WILL PERSIST IN THE FAR NORTHERN GULF DUE TO THE GRADIENT BETWEEN THE CLIMATOLOGICAL LOW PRES TROUGH ALONG THE EASTERN GULF OF CALIFORNIA AND PERSISTENT HIGH PRES OVER THE GREAT BASIN. GAP WINDS...GALE WARNING FOR GULF OF TEHUANTEPEC IS EXPECTED TO EXPIRE IN A FEW HOURS WITH N TO NE WINDS DIMINISHING TO 20 TO 30 KT AND TO 20 TO 25 KT BY LATE FRI NIGHT THROUGH SAT NIGHT. THE COMBINATION OF STRONG TRADE WINDS IN THE CARIBBEAN AND LOCAL DRAINAGE EFFECTS WILL ALLOW THE FRESH WINDS TO PERSIST THROUGH THE GULF OF PAPAGAYO THROUGH THIS AFTERNOON...THEN DIMINISH TO LESS THAN 20 KT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ AGUIRRE