000 AXPZ20 KNHC 170333 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SUN JUL 17 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0130 UTC. ...ITCZ/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM LOW PRES AT 10N86W TO LOW PRES AT 17N105W TO 12N111W TO 07N136W. THE ITCZ LIES FROM 07N136W TO BEYOND 07N140W. NUMEROUS MODERATE TO STRONG CONVECTION IS N OF THE MONSOON TROUGH BETWEEN 87W AND 89W WITH SCATTERED MODERATE CONVECTION ELSEWHERE N OF 04N BETWEEN 81W AND 90W. SCATTERED MODERATE CONVECTION LIES WITHIN 75 NM W SEMICIRCLE OF LOW PRES AT 17N105W. N OF THE MONSOON TROUGH...SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 60 NM OF THE COAST OF MAINLAND MEXICO BETWEEN 95W AND 110W. S OF THE MONSOON TROUGH...SCATTERED MODERATE ISOLATED STRONG CONVECTION LIES FROM 10N TO 13N BETWEEN 93W AND 106W. ...DISCUSSION... A LONG WAVE TROUGH LIES ALONG THE WESTERN U.S. COAST AND EXTENDS INTO THE FORECAST AREA FROM 32N125W TO 18N134W. THIS TROUGH WILL BE RELOADED WITH NORTHERN STREAM ENERGY SUN...SHIFTING THE MEAN TROUGH WESTWARD THROUGH THE NORTHERN PORTION OF THE FORECAST AREA. THIS PERSISTENT TROUGHING ALOFT OVER THE NE PACIFIC IS BLOCKING THE MIGRATION OF THE DEEP LAYER HIGH PRES ASSOCIATED WITH THE SUBTROPICAL HIGH. THE SURFACE HIGH IS EXPECTED TO REMAIN ANCHORED N OF HAWAII ALONG 40N...NW OF ITS CLIMATOLOGICAL POSITION. TRADE WINDS HAVE DIMINISHED TO LESS THAN 20 KT UNDER THE RELATIVELY WEAK PRES GRADIENT BETWEEN THE ITCZ AND THIS DISPLACED SUBTROPICAL HIGH. THESE CONDITIONS WILL CONTINUE FOR THE NEXT FEW DAYS. MEANWHILE...THE 1648 UTC ASCAT PASS SHOWS WIDESPREAD FRESH N TO NW WINDS OFF THE W COAST OF THE BAJA PENINSULA AND AS FAR S AS 20N WHILE SHIP 3FQO4 REPORTED 21 KT NW WINDS NEAR 26N117W AT 2100 UTC. THESE WINDS ARE EXPECTED TO DIMINISH OVERNIGHT SUN NIGHT AS THE SURFACE REFLECTION OF THE NORTHERN STREAM ENERGY REINFORCING THE MEAN TROUGHING ALOFT OFF THE U.S. WEST COAST DISRUPTS THE STRONG PRES GRADIENT OVER NE WATERS. THE AFOREMENTIONED BLOCKING PATTERN ALOFT ALSO EXTENDS INTO THE CENTRAL U.S. WHERE A STRONG ANTICYCLONE OVER NEBRASKA IS EXPECTED TO REMAIN THE NEXT FEW DAYS. AN UPPER RIDGE EXTENDS SW FROM THIS ANTICYCLONE THROUGH NW MEXICO AND THE CENTRAL GULF OF CALIFORNIA TO 26N113W TO 18N125W. THIS UPPER RIDGE WILL DRIFT SLOWLY NORTHWESTWARD AS THE TROUGHING TO IS E SHIFTS WESTWARD. A WEAK UPPER TROUGH PARALLELS THIS RIDGE TO ITS SE AND EXTENDS THROUGH CABO CORRIENTES...MEXICO TO 16N110W. A SECOND RIDGE THEN PARALLELS THIS TROUGH TO ITS SE. THIS RIDGE EXTENDS FROM A WEAK ANTICYCLONE OVER THE SW GULF OF MEXICO TO 13N95W. DIFFLUENCE OFF THE COAST OF SOUTHERN MEXICO BETWEEN THIS SOUTHERN RIDGE AXIS AND THE UPPER TROUGH TO ITS N IS ENHANCING CONVECTION ALONG THE MONSOON TROUGH...INCLUDING NEAR A LOW PRES SYSTEM AT 17N105W. THIS CONVECTION IS DESCRIBED IN THE SECTION ABOVE. FRESH TO STRONG SW WINDS S OF THIS AREA OF ENHANCED CONVECTION ARE FEEDING LOW LEVEL SUBTROPICAL MOISTURE TOWARD THE MONSOON TROUGH. A WELL ORGANIZED MID LEVEL LOW IS BEGINNING TO MAKE ITS WAY OFF THE COSTA RICAN COAST AND INTO THE PACIFIC. IT IS REFLECTING A 1009 MB LOW AT THE SURFACE NEAR 10N86W. UPPER LEVEL DIFFLUENCE LIES OVER THIS LOW BETWEEN 30 TO 50 KT NE WINDS ALOFT S OF 09N AND LIGHTER NE WINDS ALOFT ACROSS SOUTHERN CENTRAL AMERICA. THE ASSOCIATED UPPER LEVEL SPEED DIFFLUENCE IS ENHANCING THE LARGE AREA OF DENSE CLOUDINESS AND CONVECTION OVER THE PACIFIC WATERS DESCRIBED IN THE SECTION ABOVE...WITH THE HEAVIEST RAINFALL FOUND OVER THE GULF OF FONSECA AND INLAND OVER EL SALVADOR AND WESTERN HONDURAS JUST W OF THE MID LEVEL LOW. THE UPPER LEVEL NORTHEASTERLY FLOW IS ADVECTING THE DEBRIS MOISTURE S OF THE EQUATOR TO THE E OF 105W. WIDESPREAD RAINFALL...WITH LOCALIZED TRAINING DEEP CONVECTION...IS EXPECTED TO PERSIST ACROSS CENTRAL AMERICA DURING THE NEXT FEW DAYS. THIS MAY RESULT IN FLASH FLOODS AND MUDSLIDES THROUGH THE WEEKEND. THE SURFACE LOW IS EXPECTED TO TRACK WESTWARD ALONG 10N OVER THE NEXT TWO DAYS AND HAS THE POTENTIAL TO DEEPEN. $$ SCHAUER 000 AXPZ20 KNHC 170333 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SUN JUL 17 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0130 UTC. ...ITCZ/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM LOW PRES AT 10N86W TO LOW PRES AT 17N105W TO 12N111W TO 07N136W. THE ITCZ LIES FROM 07N136W TO BEYOND 07N140W. NUMEROUS MODERATE TO STRONG CONVECTION IS N OF THE MONSOON TROUGH BETWEEN 87W AND 89W WITH SCATTERED MODERATE CONVECTION ELSEWHERE N OF 04N BETWEEN 81W AND 90W. SCATTERED MODERATE CONVECTION LIES WITHIN 75 NM W SEMICIRCLE OF LOW PRES AT 17N105W. N OF THE MONSOON TROUGH...SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 60 NM OF THE COAST OF MAINLAND MEXICO BETWEEN 95W AND 110W. S OF THE MONSOON TROUGH...SCATTERED MODERATE ISOLATED STRONG CONVECTION LIES FROM 10N TO 13N BETWEEN 93W AND 106W. ...DISCUSSION... A LONG WAVE TROUGH LIES ALONG THE WESTERN U.S. COAST AND EXTENDS INTO THE FORECAST AREA FROM 32N125W TO 18N134W. THIS TROUGH WILL BE RELOADED WITH NORTHERN STREAM ENERGY SUN...SHIFTING THE MEAN TROUGH WESTWARD THROUGH THE NORTHERN PORTION OF THE FORECAST AREA. THIS PERSISTENT TROUGHING ALOFT OVER THE NE PACIFIC IS BLOCKING THE MIGRATION OF THE DEEP LAYER HIGH PRES ASSOCIATED WITH THE SUBTROPICAL HIGH. THE SURFACE HIGH IS EXPECTED TO REMAIN ANCHORED N OF HAWAII ALONG 40N...NW OF ITS CLIMATOLOGICAL POSITION. TRADE WINDS HAVE DIMINISHED TO LESS THAN 20 KT UNDER THE RELATIVELY WEAK PRES GRADIENT BETWEEN THE ITCZ AND THIS DISPLACED SUBTROPICAL HIGH. THESE CONDITIONS WILL CONTINUE FOR THE NEXT FEW DAYS. MEANWHILE...THE 1648 UTC ASCAT PASS SHOWS WIDESPREAD FRESH N TO NW WINDS OFF THE W COAST OF THE BAJA PENINSULA AND AS FAR S AS 20N WHILE SHIP 3FQO4 REPORTED 21 KT NW WINDS NEAR 26N117W AT 2100 UTC. THESE WINDS ARE EXPECTED TO DIMINISH OVERNIGHT SUN NIGHT AS THE SURFACE REFLECTION OF THE NORTHERN STREAM ENERGY REINFORCING THE MEAN TROUGHING ALOFT OFF THE U.S. WEST COAST DISRUPTS THE STRONG PRES GRADIENT OVER NE WATERS. THE AFOREMENTIONED BLOCKING PATTERN ALOFT ALSO EXTENDS INTO THE CENTRAL U.S. WHERE A STRONG ANTICYCLONE OVER NEBRASKA IS EXPECTED TO REMAIN THE NEXT FEW DAYS. AN UPPER RIDGE EXTENDS SW FROM THIS ANTICYCLONE THROUGH NW MEXICO AND THE CENTRAL GULF OF CALIFORNIA TO 26N113W TO 18N125W. THIS UPPER RIDGE WILL DRIFT SLOWLY NORTHWESTWARD AS THE TROUGHING TO IS E SHIFTS WESTWARD. A WEAK UPPER TROUGH PARALLELS THIS RIDGE TO ITS SE AND EXTENDS THROUGH CABO CORRIENTES...MEXICO TO 16N110W. A SECOND RIDGE THEN PARALLELS THIS TROUGH TO ITS SE. THIS RIDGE EXTENDS FROM A WEAK ANTICYCLONE OVER THE SW GULF OF MEXICO TO 13N95W. DIFFLUENCE OFF THE COAST OF SOUTHERN MEXICO BETWEEN THIS SOUTHERN RIDGE AXIS AND THE UPPER TROUGH TO ITS N IS ENHANCING CONVECTION ALONG THE MONSOON TROUGH...INCLUDING NEAR A LOW PRES SYSTEM AT 17N105W. THIS CONVECTION IS DESCRIBED IN THE SECTION ABOVE. FRESH TO STRONG SW WINDS S OF THIS AREA OF ENHANCED CONVECTION ARE FEEDING LOW LEVEL SUBTROPICAL MOISTURE TOWARD THE MONSOON TROUGH. A WELL ORGANIZED MID LEVEL LOW IS BEGINNING TO MAKE ITS WAY OFF THE COSTA RICAN COAST AND INTO THE PACIFIC. IT IS REFLECTING A 1009 MB LOW AT THE SURFACE NEAR 10N86W. UPPER LEVEL DIFFLUENCE LIES OVER THIS LOW BETWEEN 30 TO 50 KT NE WINDS ALOFT S OF 09N AND LIGHTER NE WINDS ALOFT ACROSS SOUTHERN CENTRAL AMERICA. THE ASSOCIATED UPPER LEVEL SPEED DIFFLUENCE IS ENHANCING THE LARGE AREA OF DENSE CLOUDINESS AND CONVECTION OVER THE PACIFIC WATERS DESCRIBED IN THE SECTION ABOVE...WITH THE HEAVIEST RAINFALL FOUND OVER THE GULF OF FONSECA AND INLAND OVER EL SALVADOR AND WESTERN HONDURAS JUST W OF THE MID LEVEL LOW. THE UPPER LEVEL NORTHEASTERLY FLOW IS ADVECTING THE DEBRIS MOISTURE S OF THE EQUATOR TO THE E OF 105W. WIDESPREAD RAINFALL...WITH LOCALIZED TRAINING DEEP CONVECTION...IS EXPECTED TO PERSIST ACROSS CENTRAL AMERICA DURING THE NEXT FEW DAYS. THIS MAY RESULT IN FLASH FLOODS AND MUDSLIDES THROUGH THE WEEKEND. THE SURFACE LOW IS EXPECTED TO TRACK WESTWARD ALONG 10N OVER THE NEXT TWO DAYS AND HAS THE POTENTIAL TO DEEPEN. $$ SCHAUER