000 AXPZ20 KNHC 082142 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC THU JAN 08 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 2100 UTC. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...05N77W TO 04N95W TO 08N120W TO 07N125W TO 08N133W TO 06N140W. SCATTERED MODERATE CONVECTION WITHIN 60 NM N OF AXIS BETWEEN 133W AND 136W. ...DISCUSSION... TRADES... AN AMPLIFIED BUT PROGRESSIVE MID- TO UPPER-LEVEL PATTERN IS FORECAST TO CONTINUE FOR THE REMAINDER OF THIS WEEK ACROSS THE TROPICAL AND SUBTROPICAL EAST PACIFIC. MORE SPECIFICALLY...A SHORTWAVE TROUGH DIGGING INTO THE WEST COAST TODAY SHOULD SWEEP THROUGH THE WEST CENTRAL CONUS AND EVENTUALLY DIG INTO THE EASTERN STATES LATE IN THE WEEKEND...AS A ROBUST RIDGE BUILDS IN ITS WAKE OVER THE MID-LATITUDE NORTHEAST PACIFIC. AT THE SURFACE...A 1032 MB SURFACE HIGH IS CENTERED IN THE CENTRAL PACIFIC NEAR 40N137W. NE TRADE WINDS OF 20 KT...AND OCCASIONALLY TO 25 KT...ARE AFFECTING AREAS S OF THE SURFACE HIGH MOSTLY FROM 10N TO 25N W OF 130W. HOWEVER...AS THE SHORTWAVE TO THE NORTH PASSES BY...HIGH PRES SHOULD REBUILD FARTHER NORTH...CLOSER TO THE WEST COAST. THIS SHOULD FAVOR A REDUCTION IN PRESSURE GRADIENT AND A COMMENSURATE BUT GRADUAL DECREASE IN AREAL COVERAGE AND INTENSITY OF TRADES OVER THIS AREA. THE PERSISTENT TRADE WINDS CONTINUE TO RESULT IN SEA HEIGHTS OF 8 TO 11 FT IN MIXED NW AND NE SWELL BUT WILL VERY GRADUALLY SUBSIDE THROUGH LATE WEEK AFTER TRADES WEAKEN SOME. ADDITIONALLY...A MID/UPPER-LEVEL LOW IS CENTERED NEAR 18N130W. HOWEVER...SUBSIDENCE ASSOCIATED WITH THE SURFACE HIGH IS CURRENTLY INHIBITING THE DEVELOPMENT OF A SURFACE TROUGH ASSOCIATED WITH THE LOW. HOWEVER...IT IS POSSIBLE THAT THE PHASING OF THE LOW WITH THE AFOREMENTIONED UPPER TROUGH COULD RESULT IN THE OCCASIONAL DEVELOPMENT OF A SURFACE TROUGH DURING THE NEXT FEW DAYS. THIS COULD CAUSE TEMPORARY ENHANCEMENTS TO THE TRADE WINDS ACROSS THE NORTHERN PERIPHERY OF ANY SURFACE TROUGHS THAT DEVELOP. GULF OF PAPAGAYO... A MORNING QUIKSCAT PASS SUGGESTED THAT NE TO E WINDS OF UP TO 20 KT ARE OCCURRING OVER A VERY NARROW AREA...ABOUT 15 NM EITHER SIDE OF 11N BETWEEN 85.5W AND 87W. HOWEVER...AS A DEEP MID- TO UPPER-LEVEL TROUGH DEVELOPS OVER THE EASTERN CONUS THE NEXT FEW DAYS...STRONG HIGH PRESSURE SHOULD BUILD SOUTHWARD AND COVER MUCH OF THE WESTERN CARIBBEAN AND CENTRAL AMERICA. THIS SHOULD RESULT IN AN INCREASE IN TRADES...FIRST OVER THE WESTERN CARIBBEAN AND EVENTUALLY NEAR AND DOWNSTREAM OF THE GULF OF PAPAGAYO. WITHIN 48 HOURS...MARINERS CAN EXPECT NE TO E WINDS OF 20 TO 25 KT AND GUSTY...WITH SEAS OF UP TO 10 FT IN STEEP WIND WAVES. THESE WINDS WILL BE LIKELY FLUCTUATE BETWEEN DAY AND NIGHT AS A RESULT OF A DIURNAL SIGNAL TIED TO LOCAL DRAINAGE NEAR THE ENTRANCE AREA AT THE GULF OF PAPAGAYO. GULF OF CALIFORNIA... THE HIGHLY AMPLIFIED UPPER RIDGE FORECAST TO BUILD OVER THE E PACIFIC AND FAR W CONUS THIS WEEKEND SHOULD LEAD TO A STRONG SURFACE RIDGE EXTENDING FROM THE GREAT BASIN TO THE NORTHERN ROCKIES. IN FACT...NUMERICAL MODEL GUIDANCE SUGGESTS THAT A 1045 MB SURFACE HIGH COULD SET UP OVER SE IDAHO BY SATURDAY. THIS PATTERN WILL BE PARTICULARLY FAVORABLE FOR THE DEVELOPMENT OF STRONG NORTHWESTERLY GALES THROUGH THE GULF OF CALIFORNIA THIS WEEKEND. THE WINDS SHOULD SHOULD SPREAD FROM NORTH TO SOUTH THROUGH THE GULF OF CALIFORNIA FOLLOWING THE FRONTAL PASSAGE...WITH PEAK WINDS OF 35 TO 45 KT OVER THE FAR NORTH AND SEAS BUILDING TO 10 FT. GULF OF TEHUANTEPEC... A STRONG COLD FRONT ASSOCIATED WITH THE UPPER TROUGH DIGGING INTO THE EASTERN CONUS WILL SURGE SOUTHWARD ACROSS THE WESTERN GULF THIS WEEKEND...FOLLOWED BY A 1032 MB SURFACE HIGH BUILDING OVER S TEXAS. THIS WILL QUICKLY INCREASE THE PRESSURE GRADIENT BETWEEN THE BAY OF CAMPECHE AND THE GULF OF TEHUANTEPEC. CONSEQUENTLY...STRONG WINDS WILL FUNNEL THROUGH THE ISTHMUS OF TEHUANTEPEC...RESULTING IN STRONG GALE FORCE WINDS...POSSIBLY TO STORM FORCE WINDS...NEAR AND DIRECTLY DOWNWIND OF THE GULF OF TEHUANTEPEC LATE THIS WEEKEND AND EARLY NEXT WEEK. $$ COHEN/CANGIALOSI/KIMBERLAIN