000 AXPZ20 KNHC 040318 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC FRI JUN 04 2010 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0300 UTC. ...TROPICAL WAVE... TROPICAL WAVE EXTENDS FROM CENTRAL NICARAGUA NEAR 12N85W TO 04N81W AND IS MOVING W NEAR 5 KT. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WAS WITHIN 150 NM W AND 75 NM E OF THE TROPICAL WAVE INCLUDING OVER FAR WESTERN PANAMA...COSTA RICA...AND SW NICARAGUA. THE WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE AXIS LIES ALONG 10N90W TO 08N100W TO 11N119W TO 08N129W TO 07N140W. SCATTERED MODERATE CONVECTION WAS WITHIN 60 NM N AND 90 NM S OF THE ITCZ AXIS BETWEEN 102W AND 113W...WITHIN 90 NM S OF THE ITCZ AXIS BETWEEN 123W AND 128W...AND WITHIN 120 NM EITHER SIDE OF THE ITCZ AXIS W OF 134W. THERE ARE TWO TROUGHS EMBEDDED IN THE ITCZ. THE EASTERN TROUGH WAS FROM 13N89W TO 05N92W AND HAD SCATTERED MODERATE CONVECTION N OF THE TROUGH WITHIN 45 NM OF THE COAST BETWEEN 87W AND 93W. THE WESTERN TROUGH WAS FROM 12N118W TO 07N123W AND HAD SCATTERED MODERATE CONVECTION WITHIN 60 NM W AND 120 NM E OF TROUGH. ...DISCUSSION... SUBTROPICS... A MORE AMPLIFIED UPPER PATTERN IS SETTING UP SHOP N OF 20N...WITH A SLOW MOVING UPPER LOW OVER THE NW GULF OF MEXICO FORECAST TO FORCE THE ANTICYCLONE CURRENTLY NEAR 30N122W ON A SLOW NORTHEASTWARD PATH INTO THE SW U.S. THE TAIL OF THE UPPER TROUGH HAS PINCHED OFF TWO UPPER LOWS...ONE NEAR 22N121W AND ANOTHER NEAR 25N142W. THE EASTERN LOW IS EXPECTED TO REMAIN RELATIVELY STATIONARY WHILE THE WESTERN LOW WILL SLOWLY SLIDE SW OVER THE NEXT TWO DAYS. UPPER LEVEL SOUTHWESTERLY WINDS WILL INCREASE TO 50 KT ON THE SE SIDE OF THE LOW BY SAT. REAR RIGHT QUADRANT DIFFLUENCE ALONG THE ITCZ ASSOCIATED WITH THIS JET SHOULD HELP THE CAUSE FOR CONVECTION JUST W OF THE AREA...WITH THE JET TRANSPORTING THE MID TO UPPER LEVEL CONVECTIVE BLOW OFF MOISTURE NORTHEASTWARD INTO W SUBTROPICAL WATERS. AT THE SURFACE...1020 MB HIGH PRES NEAR 30N129W WILL DRIFT SLIGHTLY E WITH LITTLE CHANGE IN STRENGTH OVER THE NEXT TWO DAYS. THE HIGH WILL BE HELD SOUTH OF 30N BY A SERIES OF NORTHERN STREAM COLD FRONTS PASSING TO ITS N. NW TO N WINDS OFF THE CALIFORNIA COAST INDUCED BY THE PRESSURE GRADIENT BETWEEN LOWER PRES OVER THE SW U.S. AND THE RIDGE EXTENDING FROM THE HIGH CENTER TO THE CENTRAL CALIFORNIA COAST HAVE BROUGHT 8 FT NW SWELL INTO NE WATERS. 20 KT WINDS WILL SHIFT S INTO FORECAST WATERS BY FRI EVENING AS THE COLD FRONT CURRENTLY PASSING N OF THE SUBTROPICAL HIGH MOVES INTO THE WESTERN U.S. AND FURTHER INCREASES THE PRESSURE GRADIENT. THE 1914 UTC ASCAT PASS SHOWS EASTERLY TRADE WINDS TO 20 KT HAVE SHRUNK TO A SMALL AREA N OF THE ITCZ OVER FAR W WATERS...BUT THESE WINDS ARE EXPECTED TO DIMINISH TO LESS THAN 20 KT OVERNIGHT UNDER THE INFLUENCE OF THE WEAK SUBTROPICAL HIGH. TROPICS... DIFFLUENT FLOW BETWEEN THE SW SIDE OF THE UPPER LEVEL ANTICYCLONE OVER THE CARIBBEAN NEAR 17N84W AND THE NW SIDE OF THE ANTICYCLONE OVER SOUTH AMERICA NEAR 10N62W LIES OVER A MAXIMUM OF DEEP LAYER MOISTURE NEAR THE ITCZ OVER FAR EASTERN WATERS. THE EASTERN SURFACE TROUGH MENTIONED IN THE ITCZ SECTION AND THE TROPICAL WAVE DETAILED ABOVE LIE IN THIS REGION. UPPER LEVEL NORTHEASTERLY WINDS ARE EXPECTED TO STRENGTHEN OVER THIS REGION AS THE ANTICYCLONE OVER THE CARIBBEAN SHIFTS NE OVER THE NEXT FEW DAYS. THIS SHOULD DECREASE THE LIKELIHOOD OF DEEP CONVECTION. THE OTHER FOCUS FOR CONVECTION IS THE WESTERN TROUGH EMBEDDED IN THE ITCZ. THIS TROUGH LIES UNDER A REGION A LIGHT UPPER LEVEL FLOW WEDGED BETWEEN A ZONAL 30-40 KT WESTERLY JET TO ITS N ALONG 20N AND 20-30 KT NE WINDS PRIMARILY S OF 09N. CONDITIONS SHOULD REMAIN RELATIVELY UNCHANGED NEAR THE TROUGH ON FRI...BUT LOOK FOR INCREASED WESTERLY WIND SHEAR TO APPROACH THE SYSTEM ON SAT AS THE PATTERN ALOFT TO THE N BECOMES MORE AMPLIFIED. $$ SCHAUER