000 AXPZ20 KNHC 150957 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC FRI JUL 15 2011 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0915 UTC. ...ITCZ/MONSOON TROUGH... MONSOON TROUGH AXIS MEANDERS ACROSS CENTRAL AMERICA FROM DEVELOPING LOW PRES ALONG THE NICARAGUA-COSTA RICA BORDER NW TO NEAR 19N102W. A SECOND SEGMENT OF MONSOON TROUGH EXTENDED FROM BROAD CYCLONIC TURNING NEAR 17N11W TO 15N119W TO 09N129W WHERE IT THEN BECOME ITCZ...EXTENDING THROUGH 06N140W. SCATTERED MODERATE ISOLATES STRONG CONVECTION WAS WITHIN 90 NM OF ITCZ AXIS. SCATTERED MODERATE TO STRONG CONVECTION WAS FROM 03N BETWEEN 80W AND 89W TO THE COAST OF COSTA RICA AND NICARAGUA. SCATTERED TO LOCALLY NUMEROUS STRONG CONVECTION WAS WITHIN 210 NM OF MEXICAN COAST BETWEEN 93W AND 106W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS ELSEWHERE FROM 07N TO 12N BETWEEN 97W AND 124W. ...DISCUSSION... AT UPPER LEVELS...A STRONG BLOCKING RIDGE ACROSS CENTRAL N AMERICA ALONG ABOUT 96-97W WAS CENTERED ON AN ANTICYCLONE OVER OKLAHOMA...WITH THIS RIDGE FORECAST TO REMAIN IN PLACE FOR THE NEXT FEW DAYS BEFORE BEGINNING TO SHIFT SLOWLY NE DURING THE MIDDLE OF NEXT WEEK. THIS RIDGE HAS HALTED TO FORWARD PROGRESS OF A LONG WAVE UPPER TROUGH EXTENDING FROM WRN CANADA SW TO A WEAKENING MIDDLE TO UPPER VORTEX NEAR 34N128W THEN CONTINUES TO NEAR 26N135W. BROAD CYCLONIC FLOW ALOFT COVERS THE AREA N OF 24N W OF 115W. S OF THIS BROAD CYCLONIC FLOW...AN UPPER ANTICYCLONE WAS CENTERED NEAR 20N137W AND SHIFTING GRADUALLY SW. MIDDLE TO UPPER CONVERGENCE WAS YIELDING A VERY STABLE ATMOSPHERE GENERALLY N OF 18N AND W OF 115W. TO THE S AND SE OF THESE FEATURES...WINDS ALOFT WERE NE TO ELY AND WERE PROVIDING A MODESTLY SHEARED ENVIRONMENT ALOFT CONDUCIVE FOR THE DEEP CONVECTION DESCRIBED ABOVE. AT LOW TO MIDDLE LEVELS...THE GFS MODEL DEPICTS DEEP LAYERED MONSOONAL FLOW ELONGATED NW TO SE FROM COASTAL MEXICO NEAR MANZANILLO TO COSTA RICA AND WRN PANAMA AND THE ADJACENT SW CARIBBEAN AND PACIFIC WATERS. ABUNDANT TROPICAL MOISTURE CONTINUES TO CONVERGE ACROSS THIS REGION FROM 110W TO THE FAR SW CARIBBEAN. SATELLITE IMAGERY THE PAST 6 HOURS OR SO CONFIRM GLOBAL MODEL FORECASTS INDICATING TWO CENTRAL CYCLONIC CIRCULATIONS DEVELOPING EACH END OF THE MONSOON TROUGH...ONE ACROSS SW MEXICO...AND THE OTHER STRADDLING WRN PANAMA...COSTA RICA...AND NICARAGUA. RECENT SCATTEROMETER PASSES SUGGEST SW TO WLY WINDS ACROSS THE NEAR AND OFFSHORE PACIFIC WATERS OF COSTA RICA ASSOCIATED WITH A DEVELOPING LOW...WHILE WLY WINDS AROUND 20 KT WERE SUGGESTED FROM 07N TO 14N BETWEEN 96W AND 103W. THESE ZONES OF FRESH MONSOONAL FLOW WERE AIDING IN THE INITIATION OF THE ABOVE DESCRIBED CONVECTION. GLOBAL MODELS ARE SLOWLY COMING INTO BETTER AGREEMENT ON THE EVOLUTION OF THE MONSOONAL TROUGH AND ASSOCIATED LOWS OVER THE NEXT FEW DAYS. THIS TROUGH IS EXPECTED TO BECOME SOMEWHAT MORE W TO E ALIGNED OVER THE NEXT FEW DAYS AND ALLOW A BROAD SURFACE LOW TO DEVELOP OFF THE SW MEXICAN COAST LATE SAT...WITH SOME POTENTIAL FOR INTENSIFICATION SUN THROUGH MON AS IT MOVES W OVER WARM WATERS. MEANWHILE...LOW PRES STRADDLING COSTA RICA IS SUGGESTED TO CONTINUE TO INTERACT WITH THESE CENTRAL AMERICAN LAND MASSES AND EVENTUALLY FULLY EMERGE OFF THE NW COAST OF COSTA RICA AND SW NICARAGUA LATE SUN OR MONDAY...AND COULD ALSO INTENSIFY AS IT MOVES W OVER WARM WATERS. THE GFS MODEL CONTINUES TO BE VERY AGGRESSIVE IN DEVELOPING THE LOW OFF OF COSTA RICA...AND DEEPENS IT VERY QUICKLY SUN-MON. HOWEVER...THESE MONSOONAL TYPE LOWS ARE TYPICALLY SLOW TO DEVELOP...AND HAVE TRENDED WITH SLOWER DEVELOPMENT INDICATED BY THE OTHER GLOBAL MODELS. REGARDLESS OF THE SHORT TERM EVOLUTION OF THESE LOWS...FRESH TO STRONG SW TO W MONSOONAL FLOW WILL CONTINUE FOR THE NEXT 36-48 HOURS ACROSS MUCH OF THE TROPICAL EPAC E OF 90W AND ACROSS THE OFFSHORE MEXICAN WATERS BETWEEN ACAPULCO AND THE GULF OF TEHUANTEPEC. ABUNDANT TROPICAL MOISTURE AND PERSISTENT DEEP CONVECTION ACROSS CENTRAL AMERICA DURING THE NEXT FEW DAYS WILL CONTINUE TO PRODUCE WIDESPREAD RAINFALL AND PERIODS OF VERY HEAVY RAINS RESULTING IN FLASH FLOODS AND MUDSLIDES THROUGH THE WEEKEND. LONGER DURATION RIVER FLOODING MAY ALSO BE SEEN INTO EARLY NEXT WEEK. ADDITIONAL INFORMATION IS CONTAINED IN TAFB GRAPHICASTS AT HTTP://WWW.HURRICANES.GOV/MARINE. W OF 110W...SCATTEROMETER AND SHIP DATA SHOW FRESH NW FLOW ALONG THE COAST OF BAJA PERSISTING BETWEEN 1037 MB HIGH PRES NEAR 42N154W...AND TROUGHING OVER THE GULF OF CALIFORNIA...AND THIS SHOULD PERSIST THROUGH 48 HOURS WITH NW WINDS TO 20 KT DEVELOPING THROUGH THE CENTRAL GULF OF CALIFORNIA WITHIN 24 HOURS. FURTHER SOUTH...TRADE WINDS REMAIN ANOMALOUSLY LIGHT. REGIONAL SEAS ARE CURRENTLY DOMINATED BY FADING LONG PERIOD SW SWELL...WITH A NEW PULSE OF S SWELL EXPECTED TO CROSS THE EQUATOR LATE SAT. $$ STRIPLING 000 AXPZ20 KNHC 150957 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC FRI JUL 15 2011 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0915 UTC. ...ITCZ/MONSOON TROUGH... MONSOON TROUGH AXIS MEANDERS ACROSS CENTRAL AMERICA FROM DEVELOPING LOW PRES ALONG THE NICARAGUA-COSTA RICA BORDER NW TO NEAR 19N102W. A SECOND SEGMENT OF MONSOON TROUGH EXTENDED FROM BROAD CYCLONIC TURNING NEAR 17N11W TO 15N119W TO 09N129W WHERE IT THEN BECOME ITCZ...EXTENDING THROUGH 06N140W. SCATTERED MODERATE ISOLATES STRONG CONVECTION WAS WITHIN 90 NM OF ITCZ AXIS. SCATTERED MODERATE TO STRONG CONVECTION WAS FROM 03N BETWEEN 80W AND 89W TO THE COAST OF COSTA RICA AND NICARAGUA. SCATTERED TO LOCALLY NUMEROUS STRONG CONVECTION WAS WITHIN 210 NM OF MEXICAN COAST BETWEEN 93W AND 106W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS ELSEWHERE FROM 07N TO 12N BETWEEN 97W AND 124W. ...DISCUSSION... AT UPPER LEVELS...A STRONG BLOCKING RIDGE ACROSS CENTRAL N AMERICA ALONG ABOUT 96-97W WAS CENTERED ON AN ANTICYCLONE OVER OKLAHOMA...WITH THIS RIDGE FORECAST TO REMAIN IN PLACE FOR THE NEXT FEW DAYS BEFORE BEGINNING TO SHIFT SLOWLY NE DURING THE MIDDLE OF NEXT WEEK. THIS RIDGE HAS HALTED TO FORWARD PROGRESS OF A LONG WAVE UPPER TROUGH EXTENDING FROM WRN CANADA SW TO A WEAKENING MIDDLE TO UPPER VORTEX NEAR 34N128W THEN CONTINUES TO NEAR 26N135W. BROAD CYCLONIC FLOW ALOFT COVERS THE AREA N OF 24N W OF 115W. S OF THIS BROAD CYCLONIC FLOW...AN UPPER ANTICYCLONE WAS CENTERED NEAR 20N137W AND SHIFTING GRADUALLY SW. MIDDLE TO UPPER CONVERGENCE WAS YIELDING A VERY STABLE ATMOSPHERE GENERALLY N OF 18N AND W OF 115W. TO THE S AND SE OF THESE FEATURES...WINDS ALOFT WERE NE TO ELY AND WERE PROVIDING A MODESTLY SHEARED ENVIRONMENT ALOFT CONDUCIVE FOR THE DEEP CONVECTION DESCRIBED ABOVE. AT LOW TO MIDDLE LEVELS...THE GFS MODEL DEPICTS DEEP LAYERED MONSOONAL FLOW ELONGATED NW TO SE FROM COASTAL MEXICO NEAR MANZANILLO TO COSTA RICA AND WRN PANAMA AND THE ADJACENT SW CARIBBEAN AND PACIFIC WATERS. ABUNDANT TROPICAL MOISTURE CONTINUES TO CONVERGE ACROSS THIS REGION FROM 110W TO THE FAR SW CARIBBEAN. SATELLITE IMAGERY THE PAST 6 HOURS OR SO CONFIRM GLOBAL MODEL FORECASTS INDICATING TWO CENTRAL CYCLONIC CIRCULATIONS DEVELOPING EACH END OF THE MONSOON TROUGH...ONE ACROSS SW MEXICO...AND THE OTHER STRADDLING WRN PANAMA...COSTA RICA...AND NICARAGUA. RECENT SCATTEROMETER PASSES SUGGEST SW TO WLY WINDS ACROSS THE NEAR AND OFFSHORE PACIFIC WATERS OF COSTA RICA ASSOCIATED WITH A DEVELOPING LOW...WHILE WLY WINDS AROUND 20 KT WERE SUGGESTED FROM 07N TO 14N BETWEEN 96W AND 103W. THESE ZONES OF FRESH MONSOONAL FLOW WERE AIDING IN THE INITIATION OF THE ABOVE DESCRIBED CONVECTION. GLOBAL MODELS ARE SLOWLY COMING INTO BETTER AGREEMENT ON THE EVOLUTION OF THE MONSOONAL TROUGH AND ASSOCIATED LOWS OVER THE NEXT FEW DAYS. THIS TROUGH IS EXPECTED TO BECOME SOMEWHAT MORE W TO E ALIGNED OVER THE NEXT FEW DAYS AND ALLOW A BROAD SURFACE LOW TO DEVELOP OFF THE SW MEXICAN COAST LATE SAT...WITH SOME POTENTIAL FOR INTENSIFICATION SUN THROUGH MON AS IT MOVES W OVER WARM WATERS. MEANWHILE...LOW PRES STRADDLING COSTA RICA IS SUGGESTED TO CONTINUE TO INTERACT WITH THESE CENTRAL AMERICAN LAND MASSES AND EVENTUALLY FULLY EMERGE OFF THE NW COAST OF COSTA RICA AND SW NICARAGUA LATE SUN OR MONDAY...AND COULD ALSO INTENSIFY AS IT MOVES W OVER WARM WATERS. THE GFS MODEL CONTINUES TO BE VERY AGGRESSIVE IN DEVELOPING THE LOW OFF OF COSTA RICA...AND DEEPENS IT VERY QUICKLY SUN-MON. HOWEVER...THESE MONSOONAL TYPE LOWS ARE TYPICALLY SLOW TO DEVELOP...AND HAVE TRENDED WITH SLOWER DEVELOPMENT INDICATED BY THE OTHER GLOBAL MODELS. REGARDLESS OF THE SHORT TERM EVOLUTION OF THESE LOWS...FRESH TO STRONG SW TO W MONSOONAL FLOW WILL CONTINUE FOR THE NEXT 36-48 HOURS ACROSS MUCH OF THE TROPICAL EPAC E OF 90W AND ACROSS THE OFFSHORE MEXICAN WATERS BETWEEN ACAPULCO AND THE GULF OF TEHUANTEPEC. ABUNDANT TROPICAL MOISTURE AND PERSISTENT DEEP CONVECTION ACROSS CENTRAL AMERICA DURING THE NEXT FEW DAYS WILL CONTINUE TO PRODUCE WIDESPREAD RAINFALL AND PERIODS OF VERY HEAVY RAINS RESULTING IN FLASH FLOODS AND MUDSLIDES THROUGH THE WEEKEND. LONGER DURATION RIVER FLOODING MAY ALSO BE SEEN INTO EARLY NEXT WEEK. ADDITIONAL INFORMATION IS CONTAINED IN TAFB GRAPHICASTS AT HTTP://WWW.HURRICANES.GOV/MARINE. W OF 110W...SCATTEROMETER AND SHIP DATA SHOW FRESH NW FLOW ALONG THE COAST OF BAJA PERSISTING BETWEEN 1037 MB HIGH PRES NEAR 42N154W...AND TROUGHING OVER THE GULF OF CALIFORNIA...AND THIS SHOULD PERSIST THROUGH 48 HOURS WITH NW WINDS TO 20 KT DEVELOPING THROUGH THE CENTRAL GULF OF CALIFORNIA WITHIN 24 HOURS. FURTHER SOUTH...TRADE WINDS REMAIN ANOMALOUSLY LIGHT. REGIONAL SEAS ARE CURRENTLY DOMINATED BY FADING LONG PERIOD SW SWELL...WITH A NEW PULSE OF S SWELL EXPECTED TO CROSS THE EQUATOR LATE SAT. $$ STRIPLING