000 AXPZ20 KNHC 180244 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC MON JUL 18 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 0215 UTC. ...SPECIAL FEATURES... A 1008 MB SURFACE LOW PRES IS CENTERED NEAR 11N89W WITH SCATTERED MODERATE AND ISOLATED STRONG CONVECTION TRYING TO ORGANIZE OVER THE AREA WITHIN 180 NM OF THE S SEMICIRCLE AND NW QUADRANT. THIS LOW IS EXPECTED TO MOVE GENERALLY W-NW REACHING NEAR 12N92W LATE MONDAY...AND NEAR 13N98W LATE TUESDAY. MODEL GUIDANCE IS VERY AGGRESSIVE WITH THIS LOW QUICKLY DEEPENING... THUS FORECAST ASSOCIATED WINDS TO INCREASE TO 20 TO 30 KT WITHIN ABOUT 240 NM OF CENTER BY TUESDAY. BOTH THE GFS AND ECMWF ARE SIMILAR IN POSITIONING AT 48 HOURS WITH THE GFS SLIGHTLY MORE AGGRESSIVE ON DEVELOPMENT. THEREFORE THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT COUPLE OF DAYS. ...TROPICAL LOWS... A 1004 MB SURFACE LOW IS CENTERED NEAR 16N107W AND IS FORECAST TO GRADUALLY DISSIPATE OVER THE NEXT 24 TO 48 HOURS. SCATTERED MODERATE CONVECTION HAS TRENDED DOWNWARD OVER THE PAST 12 HOURS AS ONLY A FEW ISOLATED MODERATE CONVECTIVE CELLS REMAIN WITHIN 90 NM OF THE CENTER. THIS LOW IS EXPECTED TO MOVE NW TO NEAR 18N110W LATE MONDAY AND BECOME DISSIPATED BY LATE TUESDAY. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH IS ALONG 09N84W TO 1008 MB LOW PRES NEAR 11N89W TO 15N96W TO 1004 MB LOW PRES NEAR 16N107W TO 11N114W TO 08N137W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N137W TO 08N140W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 10N TO 13N BETWEEN 92W AND 97W. SCATTERED MODERATE CONVECTION IS FROM 09N TO 13N BETWEEN 99W AND 106W... AND FROM 07N TO 12N BETWEEN 115W AND 132W. ...DISCUSSION... A LONGWAVE UPPER LEVEL TROUGH IS ANCHORED ALONG THE W COAST OF NORTH AMERICA WITH ITS MEAN AXIS CONTINUING SOUTHWARD INTO THE DISCUSSION AREA ALONG 32N132W TO A BASE AT 17N140W. AN EMBEDDED SHORTWAVE MID-LEVEL TROUGH AND LOW IS CENTERED NEAR 25N128W AND IS ACCOMPANIED BY UPPER MOISTURE AND A WEAK COLD FRONT EXPECTED TO REMAIN NORTH OF THE AREA OVER THE NEXT 24-48 HOURS. OTHERWISE THE UPPER LEVELS ARE VERY DRY TO THE NORTH OF 14N AND WEST OF 119W. A LONGWAVE UPPER LEVEL RIDGE CONTINUES TO DOMINATE THE CENTRAL CONUS ORIGINATING FROM AN ANTICYCLONE MEANDERING OVER EASTERN KANSAS. AN ASSOCIATED RIDGE AXIS EXTENDS SOUTHWESTWARD OVER NW MEXICO AND INTO THE PACIFIC WATERS NEAR 22N122W. THIS RIDGE WILL CONTINUE TO BLOCK THE FORWARD ADVANCE OF THE PREVIOUSLY DESCRIBED UPPER LEVEL TROUGHS THROUGH TUESDAY. THEREAFTER A STRONG SHORTWAVE TROUGH IS EXPECTED TO MOVE THE LONGWAVE AXIS OVER THE NW CONUS BY EARLY WEDNESDAY AS THE ANTICYCLONE SHIFTS EASTWARD TO OVER THE MID-MISSISSIPPI RIVER VALLEY. AN EMBEDDED UPPER LEVEL CYCLONE IS SHIFTING W ACROSS NW MEXICO CENTERED NEAR 27N107W AND IS TRAILED BY A SHORTWAVE ANTICYCLONE OVER NE MEXICO. THIS IS RESULTING IN AN AREA OF UPPER DIFFLUENCE OVER CENTRAL MEXICO WITH AN AREA OF WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS NOTED OVER A MAJORITY OF CENTRAL MEXICO THIS EVENING. AN UPPER LEVEL TROUGH EXTENDS W-SW ACROSS THE CARIBBEAN FROM HISPANIOLA TO AN UPPER CYCLONE AT 12N82W. AN UPPER LEVEL RIDGE EXTENDS SW FROM NW VENEZUELA TO A CREST ALONG THE PACIFIC COAST OF COLOMBIA. AN TROPICAL UPPER ANTICYLONE IS CENTERED NEAR 07N123W WITH A RIDGE EXTENDING EASTWARD...ROUGHLY OVER THE LOWER LEVEL MONSOON TROUGH AXIS...TO A CREST AT 08N108W. THUS...THE UPPER LEVELS OF THE DEEP TROPICS ARE SOMEWHAT DIFFLUENT OVER MOST OF CENTRAL AMERICA...AND OVER THE TROPICAL PACIFIC E OF 112W. CONVECTION CONTINUES TO FLARE IN A BROAD ZONE N OF 06N BETWEEN 80W AND 105W. ELSEWHERE AT THE SURFACE...REINFORCING SW SWELL HAS CROSSED THE EQUATOR BETWEEN 80W AND 130W AND IS EXPECTED TO PROPAGATE TO THE CENTRAL AMERICA AND MEXICO COAST BY EARLY MONDAY INTO TUESDAY. SOUTHWESTERLY MONSOONAL WINDS ARE EXPECTED TO DIMINISH SOME AS THE SURFACE LOWS MOVE GENERALLY WEST-NORTHWESTWARD. $$ HUFFMAN 000 AXPZ20 KNHC 180244 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC MON JUL 18 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 0215 UTC. ...SPECIAL FEATURES... A 1008 MB SURFACE LOW PRES IS CENTERED NEAR 11N89W WITH SCATTERED MODERATE AND ISOLATED STRONG CONVECTION TRYING TO ORGANIZE OVER THE AREA WITHIN 180 NM OF THE S SEMICIRCLE AND NW QUADRANT. THIS LOW IS EXPECTED TO MOVE GENERALLY W-NW REACHING NEAR 12N92W LATE MONDAY...AND NEAR 13N98W LATE TUESDAY. MODEL GUIDANCE IS VERY AGGRESSIVE WITH THIS LOW QUICKLY DEEPENING... THUS FORECAST ASSOCIATED WINDS TO INCREASE TO 20 TO 30 KT WITHIN ABOUT 240 NM OF CENTER BY TUESDAY. BOTH THE GFS AND ECMWF ARE SIMILAR IN POSITIONING AT 48 HOURS WITH THE GFS SLIGHTLY MORE AGGRESSIVE ON DEVELOPMENT. THEREFORE THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT COUPLE OF DAYS. ...TROPICAL LOWS... A 1004 MB SURFACE LOW IS CENTERED NEAR 16N107W AND IS FORECAST TO GRADUALLY DISSIPATE OVER THE NEXT 24 TO 48 HOURS. SCATTERED MODERATE CONVECTION HAS TRENDED DOWNWARD OVER THE PAST 12 HOURS AS ONLY A FEW ISOLATED MODERATE CONVECTIVE CELLS REMAIN WITHIN 90 NM OF THE CENTER. THIS LOW IS EXPECTED TO MOVE NW TO NEAR 18N110W LATE MONDAY AND BECOME DISSIPATED BY LATE TUESDAY. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH IS ALONG 09N84W TO 1008 MB LOW PRES NEAR 11N89W TO 15N96W TO 1004 MB LOW PRES NEAR 16N107W TO 11N114W TO 08N137W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N137W TO 08N140W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 10N TO 13N BETWEEN 92W AND 97W. SCATTERED MODERATE CONVECTION IS FROM 09N TO 13N BETWEEN 99W AND 106W... AND FROM 07N TO 12N BETWEEN 115W AND 132W. ...DISCUSSION... A LONGWAVE UPPER LEVEL TROUGH IS ANCHORED ALONG THE W COAST OF NORTH AMERICA WITH ITS MEAN AXIS CONTINUING SOUTHWARD INTO THE DISCUSSION AREA ALONG 32N132W TO A BASE AT 17N140W. AN EMBEDDED SHORTWAVE MID-LEVEL TROUGH AND LOW IS CENTERED NEAR 25N128W AND IS ACCOMPANIED BY UPPER MOISTURE AND A WEAK COLD FRONT EXPECTED TO REMAIN NORTH OF THE AREA OVER THE NEXT 24-48 HOURS. OTHERWISE THE UPPER LEVELS ARE VERY DRY TO THE NORTH OF 14N AND WEST OF 119W. A LONGWAVE UPPER LEVEL RIDGE CONTINUES TO DOMINATE THE CENTRAL CONUS ORIGINATING FROM AN ANTICYCLONE MEANDERING OVER EASTERN KANSAS. AN ASSOCIATED RIDGE AXIS EXTENDS SOUTHWESTWARD OVER NW MEXICO AND INTO THE PACIFIC WATERS NEAR 22N122W. THIS RIDGE WILL CONTINUE TO BLOCK THE FORWARD ADVANCE OF THE PREVIOUSLY DESCRIBED UPPER LEVEL TROUGHS THROUGH TUESDAY. THEREAFTER A STRONG SHORTWAVE TROUGH IS EXPECTED TO MOVE THE LONGWAVE AXIS OVER THE NW CONUS BY EARLY WEDNESDAY AS THE ANTICYCLONE SHIFTS EASTWARD TO OVER THE MID-MISSISSIPPI RIVER VALLEY. AN EMBEDDED UPPER LEVEL CYCLONE IS SHIFTING W ACROSS NW MEXICO CENTERED NEAR 27N107W AND IS TRAILED BY A SHORTWAVE ANTICYCLONE OVER NE MEXICO. THIS IS RESULTING IN AN AREA OF UPPER DIFFLUENCE OVER CENTRAL MEXICO WITH AN AREA OF WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS NOTED OVER A MAJORITY OF CENTRAL MEXICO THIS EVENING. AN UPPER LEVEL TROUGH EXTENDS W-SW ACROSS THE CARIBBEAN FROM HISPANIOLA TO AN UPPER CYCLONE AT 12N82W. AN UPPER LEVEL RIDGE EXTENDS SW FROM NW VENEZUELA TO A CREST ALONG THE PACIFIC COAST OF COLOMBIA. AN TROPICAL UPPER ANTICYLONE IS CENTERED NEAR 07N123W WITH A RIDGE EXTENDING EASTWARD...ROUGHLY OVER THE LOWER LEVEL MONSOON TROUGH AXIS...TO A CREST AT 08N108W. THUS...THE UPPER LEVELS OF THE DEEP TROPICS ARE SOMEWHAT DIFFLUENT OVER MOST OF CENTRAL AMERICA...AND OVER THE TROPICAL PACIFIC E OF 112W. CONVECTION CONTINUES TO FLARE IN A BROAD ZONE N OF 06N BETWEEN 80W AND 105W. ELSEWHERE AT THE SURFACE...REINFORCING SW SWELL HAS CROSSED THE EQUATOR BETWEEN 80W AND 130W AND IS EXPECTED TO PROPAGATE TO THE CENTRAL AMERICA AND MEXICO COAST BY EARLY MONDAY INTO TUESDAY. SOUTHWESTERLY MONSOONAL WINDS ARE EXPECTED TO DIMINISH SOME AS THE SURFACE LOWS MOVE GENERALLY WEST-NORTHWESTWARD. $$ HUFFMAN