000 AXPZ20 KNHC 052157 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC SAT JUN 05 2010 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1515 UTC. ...TROPICAL WAVE... A TROPICAL WAVE IS ALONG 80W N OF 01N MOVING W AT 10 KT. NO SIGNIFICANT CONVECTION IS PRESENT WITH THE WAVE OVER FORECAST WATERS WHERE 25-30 KT EASTERLY WINDS ALOFT ARE INHIBITING THE DEVELOPMENT OF DEEP CONVECTION. ISOLATED MODERATE CONVECTION CAN BE FOUND N OF THIS WIND SHEAR OVER WESTERN PANAMA AND PORTIONS OF COSTA RICA AND NICARAGUA W OF THE WAVE AXIS. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ANALYZED ALONG 08N82W TO 12N95W TO 07N112W TO 09N123W TO 06N140W. SCATTERED MODERATE CONVECTION WAS WITHIN 120 NM EITHER SIDE OF TROUGH W OF 135W. A TROUGH IS EMBEDDED IN THE ITCZ FROM 15N95W TO 08N99W AND SCATTERED MODERATE TO STRONG CONVECTION WAS WITHIN 90 NM E AND 330 NM W OF THIS TROUGH S OF 12N. ...DISCUSSION... SUBTROPICS... THE AMPLIFIED UPPER PATTERN IN PLACE N OF 20N...WITH AN ELONGATED UPPER TROUGH FROM BROWNSVILLE...TEXAS TO MANZANILLO...MEXICO AND AN ANTICYCLONE OVER THE SW UNITED STATES...IS EXPECTED TO CHANGE LITTLE OVER THE NEXT 24 HOURS BEFORE THE ANTICYCLONE BEGINS TO SHIFT EASTWARD INTO THE PLAINS ON ITS WAY TO MERGING WITH AN ANTICYCLONE CURRENTLY OVER THE STRAITS OF FL AND YUCATAN CHANNEL. THIS WILL CUT OFF THE TROUGH FROM THE NORTHERN STREAM AND ALLOW IT TO RETROGRADE NW THROUGH NORTHERN MEXICO MON. THE TAIL OF THIS ELONGATED TROUGH HAD PINCHED OFF TWO UPPER LOWS...ONE NEAR 25N119W AND ANOTHER NEAR 20N144W. BOTH OF THESE LOWS CURRENTLY LIE WITHIN A BROAD TROUGH CONNECTED TO THE NORTHERN STREAM...BUT THE WESTERN LOW IS EXPECTED TO ESCAPE TO THE SW WHILE THE EASTERN LOW DEEPENS AND SETS UP SHOP IN THE VICINITY OF 25N125W MON AS THE NORTHERN STREAM JET LIFTS AWAY FROM THE AREA. THE SOUTHERN STREAM WESTERLY JET CURRENTLY LIES ALONG 18N W OF 115W AND TURNS SOUTHWESTERLY AS IT CROSSES W OF 135W ON THE LEADING EDGE OF THE EASTERN UPPER LOW. REAR RIGHT QUADRANT JET DYNAMICS IS ENHANCING CONVECTION ALONG THE ITCZ OVER W WATERS AND THE JET IS TRANSPORTING CONVECTIVE BLOW OFF NE INTO THE FORECAST AREA. AT THE SURFACE...THE 1023 MB SUBTROPICAL HIGH NEAR 28N138W IS EXPECTED TO GRADUALLY INTENSIFY OVER THE NEXT 24 HOURS AS IT TEMPORARILY JOINS FORCES WITH HIGH PRES BEHIND THE COLD FRONT CURRENTLY EXTENDING FROM THE NORTH EAST PACIFIC TO N OF HAWAII NEAR 30N. THE SUBTROPICAL HIGH WILL BE HELD SOUTH OF 30N BY BOTH THIS COLD FRONT AND A SECOND NORTHERN STREAM SYSTEM EXPECTED TO PASS TO ITS N ON MON. THE STRENGTHENED HIGH WILL AGAIN SUPPORT FRESH EASTERLY TRADE WINDS OVER W WATERS BY SUN AFTERNOON. AN EARLIER COLD FRONT PASSING N OF THE AREA HAS BROUGHT NW SWELL TO 8 FT INTO N CENTRAL WATERS AND IT HAS MERGED WITH NW SWELL TO 9 FT THAT HAD BEEN GENERATED BY WINDS OFF THE CALIFORNIA COAST INDUCED BY A PRESSURE GRADIENT BETWEEN LOWER PRES OVER THE GREAT BASIN AND THE RIDGE THAT EXTENDED FROM THE HIGH CENTER TO THE CENTRAL CALIFORNIA COAST. AS THE COLD FRONT OVER THE NORTH EAST PACIFIC MOVES INTO THE WESTERN U.S. ON SUN...LOOK FOR PRESSURES TO FALL IN THE SW U.S. AND WINDS TO INCREASE TO 20 KT OVER NE WATERS...KEEPING THE SEAS IN THE 8-9 FT RANGE THERE THROUGH MON. TROPICS... AS MENTIONED IN THE TROPICAL WAVE SECTION...UPPER LEVEL EASTERLY WINDS HAVE STRENGTHENED OVER FAR EASTERN WATERS. THIS SHEAR HAS LIMITED DEEP CONVECTION HERE DESPITE AMPLE DEEP LAYER MOSITURE S OF PANAMA. THE SURFACE TROUGH EMBEDDED IN THE ITCZ FROM 15N95W TO 08N99W LIES WITHIN A MAXIMUM OF DEEP LAYER MOSITURE AND IS EXPECTED TO REMAIN UNDER AN UPPER RIDGE AXIS EXTENDING E FROM AN ANTICYCLONE NEAR 12N111W THAT IS NOT EXPECTED TO MOVE MUCH OVER THE NEXT 24 HOURS BUT WILL BE REPLACED BY INCREASING EASTERLY WIND SHEAR BY MON. THIS SHOULD ALLOW CONVECTION TO CONTINUE NEAR THE TROUGH THROUGH SUN AND BEGIN TO DIMINISH MON. THERE IS INCREASING AGREEMENT AMONG THE MODEL FORECASTS FOR SURFACE LOW DEVELOPMENT ALONG THIS TROUGH. THE 1652 UTC ASCAT PASS SUPPORTS THIS IDEA. HOWEVER...THE LOW WILL LIKELY BE SHORT LIVED AFTER THE SYSTEM ENCOUNTERS THE AFOREMENTIONED EASTERLY SHEAR. A SECOND TROUGH IS EMBEDDED IN THE ITCZ FROM 15N121W TO 06N124W WITH A 1010 MB LOW ALONG IT NEAR 10N123W. DEEP LAYER MOSITURE NEAR THE TROUGH IS WANING AND THE SYSTEM CURRENTLY SHOWS NO SIGNIFICANT CONVECTIVE ACTIVITY. THE NORTH END OF THIS SYSTEM LIES UNDER 20-30 KT WESTERLY WINDS ASSOCIATED WITH THE SOUTHERN STREAM JET WHILE THE SOUTHERN PORTION LIES UNDER EASTERLY WINDS ALOFT OF SIMILAR STRENGTH. THIS SHEAR IS INHIBITING CONVECTION...AND THE UPPER LEVEL WINDS OVER THE TROUGH ARE ONLY EXPECTED TO INCREASE OVER THE NEXT FEW DAYS...DECREASING THE LIKELIHOOD OF THE DEVELOPMENT OF DEEP CONVECTION. HOWEVER...AS THE SURFACE HIGH BUILDS TO THE N...20 KT WINDS ARE EXPECTED TO CONTINUE DUE TO THE INCREASED PRES GRADIENT BETWEEN THE TROUGH AND THE HIGH. $$ SCHAUER 000 AXPZ20 KNHC 052157 CCA TWDEP TROPICAL WEATHER DISCUSSION...CORRECTION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC SAT JUN 05 2010 CORRECTED FOR VALID TIME 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 2000 UTC. ...TROPICAL WAVE... A TROPICAL WAVE IS ALONG 80W N OF 01N MOVING W AT 10 KT. NO SIGNIFICANT CONVECTION IS PRESENT WITH THE WAVE OVER FORECAST WATERS WHERE 25-30 KT EASTERLY WINDS ALOFT ARE INHIBITING THE DEVELOPMENT OF DEEP CONVECTION. ISOLATED MODERATE CONVECTION CAN BE FOUND N OF THIS WIND SHEAR OVER WESTERN PANAMA AND PORTIONS OF COSTA RICA AND NICARAGUA W OF THE WAVE AXIS. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ANALYZED ALONG 08N82W TO 12N95W TO 07N112W TO 09N123W TO 06N140W. SCATTERED MODERATE CONVECTION WAS WITHIN 120 NM EITHER SIDE OF TROUGH W OF 135W. A TROUGH IS EMBEDDED IN THE ITCZ FROM 15N95W TO 08N99W AND SCATTERED MODERATE TO STRONG CONVECTION WAS WITHIN 90 NM E AND 330 NM W OF THIS TROUGH S OF 12N. ...DISCUSSION... SUBTROPICS... THE AMPLIFIED UPPER PATTERN IN PLACE N OF 20N...WITH AN ELONGATED UPPER TROUGH FROM BROWNSVILLE...TEXAS TO MANZANILLO...MEXICO AND AN ANTICYCLONE OVER THE SW UNITED STATES...IS EXPECTED TO CHANGE LITTLE OVER THE NEXT 24 HOURS BEFORE THE ANTICYCLONE BEGINS TO SHIFT EASTWARD INTO THE PLAINS ON ITS WAY TO MERGING WITH AN ANTICYCLONE CURRENTLY OVER THE STRAITS OF FL AND YUCATAN CHANNEL. THIS WILL CUT OFF THE TROUGH FROM THE NORTHERN STREAM AND ALLOW IT TO RETROGRADE NW THROUGH NORTHERN MEXICO MON. THE TAIL OF THIS ELONGATED TROUGH HAD PINCHED OFF TWO UPPER LOWS...ONE NEAR 25N119W AND ANOTHER NEAR 20N144W. BOTH OF THESE LOWS CURRENTLY LIE WITHIN A BROAD TROUGH CONNECTED TO THE NORTHERN STREAM...BUT THE WESTERN LOW IS EXPECTED TO ESCAPE TO THE SW WHILE THE EASTERN LOW DEEPENS AND SETS UP SHOP IN THE VICINITY OF 25N125W MON AS THE NORTHERN STREAM JET LIFTS AWAY FROM THE AREA. THE SOUTHERN STREAM WESTERLY JET CURRENTLY LIES ALONG 18N W OF 115W AND TURNS SOUTHWESTERLY AS IT CROSSES W OF 135W ON THE LEADING EDGE OF THE EASTERN UPPER LOW. REAR RIGHT QUADRANT JET DYNAMICS IS ENHANCING CONVECTION ALONG THE ITCZ OVER W WATERS AND THE JET IS TRANSPORTING CONVECTIVE BLOW OFF NE INTO THE FORECAST AREA. AT THE SURFACE...THE 1023 MB SUBTROPICAL HIGH NEAR 28N138W IS EXPECTED TO GRADUALLY INTENSIFY OVER THE NEXT 24 HOURS AS IT TEMPORARILY JOINS FORCES WITH HIGH PRES BEHIND THE COLD FRONT CURRENTLY EXTENDING FROM THE NORTH EAST PACIFIC TO N OF HAWAII NEAR 30N. THE SUBTROPICAL HIGH WILL BE HELD SOUTH OF 30N BY BOTH THIS COLD FRONT AND A SECOND NORTHERN STREAM SYSTEM EXPECTED TO PASS TO ITS N ON MON. THE STRENGTHENED HIGH WILL AGAIN SUPPORT FRESH EASTERLY TRADE WINDS OVER W WATERS BY SUN AFTERNOON. AN EARLIER COLD FRONT PASSING N OF THE AREA HAS BROUGHT NW SWELL TO 8 FT INTO N CENTRAL WATERS AND IT HAS MERGED WITH NW SWELL TO 9 FT THAT HAD BEEN GENERATED BY WINDS OFF THE CALIFORNIA COAST INDUCED BY A PRESSURE GRADIENT BETWEEN LOWER PRES OVER THE GREAT BASIN AND THE RIDGE THAT EXTENDED FROM THE HIGH CENTER TO THE CENTRAL CALIFORNIA COAST. AS THE COLD FRONT OVER THE NORTH EAST PACIFIC MOVES INTO THE WESTERN U.S. ON SUN...LOOK FOR PRESSURES TO FALL IN THE SW U.S. AND WINDS TO INCREASE TO 20 KT OVER NE WATERS...KEEPING THE SEAS IN THE 8-9 FT RANGE THERE THROUGH MON. TROPICS... AS MENTIONED IN THE TROPICAL WAVE SECTION...UPPER LEVEL EASTERLY WINDS HAVE STRENGTHENED OVER FAR EASTERN WATERS. THIS SHEAR HAS LIMITED DEEP CONVECTION HERE DESPITE AMPLE DEEP LAYER MOSITURE S OF PANAMA. THE SURFACE TROUGH EMBEDDED IN THE ITCZ FROM 15N95W TO 08N99W LIES WITHIN A MAXIMUM OF DEEP LAYER MOSITURE AND IS EXPECTED TO REMAIN UNDER AN UPPER RIDGE AXIS EXTENDING E FROM AN ANTICYCLONE NEAR 12N111W THAT IS NOT EXPECTED TO MOVE MUCH OVER THE NEXT 24 HOURS BUT WILL BE REPLACED BY INCREASING EASTERLY WIND SHEAR BY MON. THIS SHOULD ALLOW CONVECTION TO CONTINUE NEAR THE TROUGH THROUGH SUN AND BEGIN TO DIMINISH MON. THERE IS INCREASING AGREEMENT AMONG THE MODEL FORECASTS FOR SURFACE LOW DEVELOPMENT ALONG THIS TROUGH. THE 1652 UTC ASCAT PASS SUPPORTS THIS IDEA. HOWEVER...THE LOW WILL LIKELY BE SHORT LIVED AFTER THE SYSTEM ENCOUNTERS THE AFOREMENTIONED EASTERLY SHEAR. A SECOND TROUGH IS EMBEDDED IN THE ITCZ FROM 15N121W TO 06N124W WITH A 1010 MB LOW ALONG IT NEAR 10N123W. DEEP LAYER MOSITURE NEAR THE TROUGH IS WANING AND THE SYSTEM CURRENTLY SHOWS NO SIGNIFICANT CONVECTIVE ACTIVITY. THE NORTH END OF THIS SYSTEM LIES UNDER 20-30 KT WESTERLY WINDS ASSOCIATED WITH THE SOUTHERN STREAM JET WHILE THE SOUTHERN PORTION LIES UNDER EASTERLY WINDS ALOFT OF SIMILAR STRENGTH. THIS SHEAR IS INHIBITING CONVECTION...AND THE UPPER LEVEL WINDS OVER THE TROUGH ARE ONLY EXPECTED TO INCREASE OVER THE NEXT FEW DAYS...DECREASING THE LIKELIHOOD OF THE DEVELOPMENT OF DEEP CONVECTION. HOWEVER...AS THE SURFACE HIGH BUILDS TO THE N...20 KT WINDS ARE EXPECTED TO CONTINUE DUE TO THE INCREASED PRES GRADIENT BETWEEN THE TROUGH AND THE HIGH. $$ SCHAUER