000 AXPZ20 KNHC 121004 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC FRI JUN 12 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 0945 UTC. ...SPECIAL FEATURE... A 1010 MB SURFACE LOW IS LOCATED NEAR 14.5N119W MOVING NW ABOUT 7 KT. LATEST SHORTWAVE IR SATELLITE IMAGERY SHOWS WHAT APPEARS TO BE A LOW LEVEL CENTER BECOMING MORE EXPOSED WITH TIME AS REMAINING MINIMAL CONVECTIVE ACTIVITY CONTINUES TO DISSIPATE. A FEW MICROWAVE PASSES FROM LATE LAST NIGHT ALSO SHOWED THAT THE LOW LEVEL CENTER HAS JUST ABOUT BECOME VOID OF DEEP CONVECTIVE ACTIVITY AS IT CONTINUES TO BE HINDERED BY STRONG SW WINDS TO ITS NW DUE TO A RATHER SHARP MID/UPPER TROUGH THAT STRETCHES NE TO SW ACROSS THE EASTERN PORTION OF THE AREA. THIS SURROUNDING ENVIRONMENT CONSISTING OF THIS UPPER FLOW PATTERN IS STRETCHING THE MOSITURE FIELD ASSOCIATED WITH THE LOW TOWARDS THE NE. IN ADDITION...DRY AIR AHEAD OF THIS TROUGH AND NE OF OF AN UPPER LEVEL ANTICYCLONE W OF THE AREA NEAR 9N145W IS BEING CHANNELED NEWD TOWARDS TO THE LOW PUTTING A CAP ON DEEP CONVECTION FROM DEVELOPING N OF THE ITCZ AND NEAR THE LOW. THE ONLY CONVECTION BEING NOTED IS A SMALL DISSIPATING CLUSTER OF SCATTERED MODERATE CONVECTION NW OF THE CENTER WITHIN 30 NM OF 16N120W. A QUIKSCAT PASS FROM VERY NEAR 0200 UTC THIS MORNING REVEALED 20-25 KT WINDS VECTORS WITHIN 150 NM IN THE NE QUADRANT OF THE LOW...AND 60 NM ELSEWHERE FROM LOW. THESE WINDS ARE FORECAST TO GRADUALLY DECREASE OVER THE NEXT 48 HOURS DUE TO VERY POOR ORGANIZATION OF THE SYSTEM WHICH IS BECOMING POORER WITH TIME. THE LOW IS FORECAST TO MOVE IN A GENERAL NW TO N DIRECTION OVER THE NEXT 48-72 HOURS AND ENCOUNTER INCREASED DEEP LAYER SHEAR AND INCREASING DRY AIR IN THE SURROUNDING ENVIRONMENT ALONG WITH COOLER SEA SURFACE TEMPERATURES. THE LOW IS LIKELY TO TRANSITION INTO A TROUGH AFTER 48 HOURS. ...ITCZ... AXIS IS CENTERED ALONG 8N87W 7N86W 6N95W 6N103W 10N112W 14N119W 7N130W 6N140W. SCATTERED STRONG CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 84W-89WW...AND WITHIN 30 NM OF THE AXIS BETWEEN 93W-97W. SCATTERED MODERATE CONVECTION EXISTS WITHIN 60 NM OF THE AXIS BETWEEN 121W-124W. SCATTERED STRONG CONVECTIVE CLUSTERS ARE INCREASING OVER THE GULF OF TEHUANTEPEC...AND ALONG THE COAST OF EL SALVADOR AND COSTA RICA. ...DISCUSSION... N OF 20N... A MID/UPPER LEVEL TROUGH ENTERS THE REGION TROUGH 32N125W...AND EXTENDS TO 25N127W TO 19N134W. THIS IS THE SAME TROUGH MENTIONED ABOVE UNDER SPECIAL FEATURES. TO THE W OF THE TROUGH...THE UPPER FLOW IS N AROUND DUE ALSO TO AN UPPER LEVEL ANTICYCLONE THAT IS WELL W OF THE AREA. TO THE SE OF THE TROUGH...AN UPPER LEVEL ANTICYCLONE IS NOTED OVER CENTRAL MEXICO WITH AN ASSOCIATED RIDGE EXTENDING WSW ACROSS THE EASTERN PORTION OF THE PACIFIC TO NEAR 15N120W. A MID/UPPER LEVEL RIDGE ENTERS THE AREA AT 10N140W AND REACHES TO 10N128W. THIS RIDGE EXTENDS W TO THE ANTICYCLONE CENTERED NEAR 9N145W. AT THE SURFACE...A RIDGE ENTERS THE DISCUSSION AREA THROUGH 32N137W AND CONTINUES SEWD TO 20N113W. THE PRES GRADIENT AT THE SOUTHERN PERIPHERY OF THIS RIDGE IS ALLOWING FOR NE TRADE WINDS TO 20 KT TO BE CONFINED FROM 10N-18N W OF 130W. THESE WINDS ARE FORECAST TO REMAIN IN PLACE DURING THE 48 HOURS...PERHAPS SHIFT SOME TO THE W. THE OVERALL PATTERN IS FORECAST TO CHANGE LITTLE DURING THE NEXT COUPLE OF DAYS AS THE TROUGH DAMPENS SOME LATE SUN. THE SURFACE PRES DIFFERENCE BETWEEN THE RIDGE AND LOWER PRES OVER THE SW U.S. WILL ALLOW FOR NW WINDS TO 20 KT TO BEEN SEEN WITHIN ABOUT 150 NM OF THE BAJA CALIFORNIA COAST... DECREASING TO WITHIN 120 NM OF THAT COAST FROM 21N-27N IN 48 HOURS. DEEPENING LOW PRES OVER THE WESTERN U.S. IN RESPONSE TO THE MID/UPPER TROUGH SHOULD ALLOW FOR TEMPORARY INSTANCES OF SW-W 20 KT ACROSS THE FAR NORTHERN GULF OF CALIFORNIA N OF ABOUT 28N THROUGH 24 HOURS WITH THIS MOMENTUM THEN CARRIED SOUTHWARD TO THE SOUTHERN PORTION OF THE GULF S OF 25N IN 48 HOURS WHERE WINDS BECOME NW TO 20 KT WITH SEAS LESS THAN 8 FT. OF SIGNIFICANCE WITH REGARDS TO THE MARINE FORECAST...S TO SW SWELLS ASSOCIATED WITH WAVE HEIGHTS OF 8-11 FT WILL CONTINUE TO OVERSPREAD THROUGHOUT THE SOUTHERN WATERS OF THE DISCUSSION AREA...WITH THE HIGHEST OF THESE SEAS IN THE FAR EASTERN SECTION...DURING THE NEXT 48 HOURS. LATEST WAVE MODEL GUIDANCE IS FOR THE RESULTING WAVES TO IMPACT THE COAST OF CENTRAL AMERICA SAT AND SUN RESULTING IN LARGE AND DANGEROUS BREAKING SURF CONDITIONS. $$ AGUIRRE