000 AXPZ20 KNHC 172130 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC TUE JUL 17 2012 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2030 UTC. ...SPECIAL FEATURES... TROPICAL STORM FABIO CENTERED NEAR 23.0N 120.7W AT 17/2100 UTC OR ABOUT 595 NM W OF THE SOUTHERN TIP OF BAJA CALIFORNIA MOVING N AT 08 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. SCATTERED MODERATE CONVECTION IS OCCURRING WITHIN 90 NM OF CENTER IN THE NORTHERN SEMICIRCLE. FABIO IS BEING STEERED NORTHWARD ON THE LEADING EDGE OF A DEEP LAYERED TROUGH OVER NORTHERN CALIFORNIA CENTERED NEAR 41N124W WITH AXIS EXTENDING S-SW TO 20N135W. FABIO IS FORECAST TO WEAKEN TO A TROPICAL DEPRESSION BY EARLY WEDNESDAY AS IT ENCOUNTERS COOLER WATERS...A DRIER AIR MASS...AND INCREASING VERTICAL WIND SHEAR. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH IS ALONG 07N78W TO 10N87W TO 09N94W TO 12N105W TO 07N116W TO 09N122W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N122W TO 11N131W TO 07N140W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 04N TO 08N BETWEEN 79W AND 86W...AND FROM 07N TO 11N BETWEEN 91W AND 97W...AND WITHIN 150 NM EITHER SIDE OF THE AXIS BETWEEN 105W AND 118W. SCATTERED MODERATE CONVECTION IS FROM 05N TO 09N BETWEEN 98W AND 103W...AND WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 118W AND 123W. ...DISCUSSION... A 1036 MB SUBTROPICAL HIGH IS CENTERED WELL NW OF THE FORECAST AREA NEAR 43N151W WITH A RIDGE AXIS EXTENDING SOUTHEASTWARD TO 20N134W. A DEEP LAYER TROUGH IS CENTERED OVER NORTHERN CALIFORNIA AND EXTENDS AN UPPER LEVEL TROUGH AXIS S-SW ALONG 32N127W TO 20N135W. THE SURFACE PRESSURE GRADIENT HAS RELAXED SUFFICIENTLY OVER NW PORTIONS OF THE DISCUSSION AREA AND ONLY A SMALL AREA OF 8 FT SEAS REMAIN N OF 29N W OF 135W THAT IS EXPECTED TO SUBSIDE BELOW 8 FT LATER THIS EVENING. OTHERWISE... FABIO REMAINS THE ONLY FEATURE WITH ELEVATED WINDS ABOVE 20 KT AND SEAS GREATER THAN 8 FT. TOWARDS THE END OF THE TWO DAY FORECAST PERIOD...SOUTHERN HEMISPHERIC SOUTHERLY SWELL BUILDS SEAS TO 8 FT GENERALLY S OF 03N BETWEEN 107W AND 120W. A BROAD ANTICYCLONIC CIRCULATION ALOFT SPANS MUCH OF THE REGION FROM S OF 20N BETWEEN 95W AND 130W. DIFFLUENCE CONTINUES TO BE MAXIMIZED ALOFT ON THE SOUTHERN EDGE OF THE ANTICYCLONE AND IS ENHANCING CONVECTION ALONG THE MONSOON TROUGH THIS EVENING. THE ANTICYCLONE WILL SHRINK ON ITS EASTERN EDGE WEDNESDAY INTO EARLY THURSDAY AS AN INVERTED UPPER LEVEL TROUGH CURRENTLY E OF 92W MOVES WESTWARD. WHILE THE MONSOON TROUGH IS EXPECTED TO REMAIN ACTIVE...THERE IS NO SIGNIFICANT MIDDLE TO LOWER LEVEL FEATURE EXPECTED TO SPIN UP ALONG IT OVER THE NEXT FEW DAYS. GAP WINDS..FRESH TO OCCASIONALLY STRONG WINDS IN THE GULF OF PAPAGAYO WILL PULSE OVER THE NEXT FEW DAYS. THE STRONGEST WINDS ARE FORECAST FOR THURSDAY MORNING AROUND 1200 UTC WHEN DRAINAGE FLOW IS MAXIMIZED. WINDS ARE THEN EXPECTED TO FALL BELOW ADVISORY CRITERIA THEREAFTER. $$ HUFFMAN