000 AXPZ20 KNHC 030308 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC FRI JUL 03 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0230 UTC. ...TROPICAL WAVE... A TROPICAL WAVE EXTENDS FROM 17N105W TO 11N106W TO 05N106W MOVING W ABOUT 12 KT. THIS WAVE COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. THE WAVE MARKS THE LEADING EDGE OF A RATHER BROAD AREA OF DISORGANIZED CLOUDINESS AND CONVECTION...AND BISECTS THE ITCZ. AT THE PRESENT TIME...ONLY ISOLATED SHOWERS ARE WITHIN 120 NM E OF THE WAVE N OF THE ITCZ. THE WAVE IS UNDER MODERATE TO STRONG ELY SHEAR OCCURRING ON THE SRN PERIPHERY OF A MID/UPPER LEVEL WARM CORE ANTICYCLONE ANCHORED OVER CENTRAL MEXICO NEAR 21N102W. ANY DEEP CONVECTION THAT DOES DEVELOP NEAR THE WAVE IS WILL LIKELY BE A RESULT OF LOW LEVEL CONVERGENCE NEAR THE ITCZ. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 6N78W 9N90W 10N105W 9N120W 6N130W 6N140W. SCATTERED STRONG CONVECTION IS WITHIN 120 NM S OF THE AXIS BETWEEN 83W-85W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM S OF THE AXIS BETWEEN 96W-102W...AND BETWEEN 109W-112W. SIMILAR ACTIVITY IS WITHIN 60 NM S OF THE AXIS BETWEEN 116W-127W. ...DISCUSSION... A NARROWING MID/UPPER LEVEL TROUGH ENTERS THE FAR NE CORNER OF THE AREA THROUGH 32N19W...THEN EXTENDS SE TO NEAR 25N117W. TO THE SW OF THE TROUGH...AN ELONGATED MID/UPPER LEVEL ANTICYCLONE IS SITUATED NEAR 18N129W WITH A RIDGE SW TO 14N140W. A LARGER DEEP LAYER TROUGH IS WELL W OF THE REGION. A PERSISTENT UPPER LEVEL SW FLOW PATTERN IS OBSERVED BETWEEN THESE FEATURES. THIS CONTINUES TO ADVECT DEEP TROPICAL UPPER LEVEL MOSITURE FROM THE CENTRAL PACIFIC NEWD INTO THE AREA FROM 18N TO 21N E TO OVER THE CREST OF THE ANTICYCLONE. ADDITIONAL UPPER LEVEL MOISTURE IS ENCROACHING INTO THE FAR NW CORNER IN ADVANCE OF THE LARGE TROUGH W OF THE TROUGH. OTHERWISE SATELLITE WATER VAPOR IMAGERY SHOWS THAT THE VAST MAJORITY OF THE DISCUSSION W OF LINE FROM 23N107W TO 17N122W TO 10N120W IS UNDER MODERATE SUBSIDENCE PROVIDING RATHER STABLE CONDITIONS AS INDICATED BY MODERATE SUBSIDENCE. VISIBLE SATELLITE IMAGERY SHOWS PATCHES OF SCATTERED TO BROKEN STRATOCUMULUS CLOUDS MOVING S AROUND THE ERN PERIPHERY OF WEAK SURFACE HIGH PRES PRESENT N OF 14N W OF 123W. WEAK HIGH PRES GENERALLY COVERS THE AREA N OF 13N W OF 125W. A LAYER OF BROKEN STRATOCUMULUS CLOUDS IS OVER THE FAR NE PART OF THE AREA N OF 18N E OF 119W TO ALONG THE COAST OF BAJA CALIFORNIA. OVER THE REMAINDER OF THE AREA E OF THE AFOREMENTIONED LINE THAT EXTENDS FROM 23N107W TO 17N122W TO 10N120W ABUNDANT UPPER LEVEL MOSITURE IS OBSERVED ON SATELLITE IMAGERY. THIS MOISTURE IS PRINCIPALLY ATTRIBUTED TO CONDITIONS ALREADY DESCRIBED ABOVE UNDER TROPICAL WAVE...BUT IS ALSO BEING ENHANCED IN THE ITCZ REGION AS THE REGION AND SURROUNDING AREAS ARE UNDER A BROAD LOW PRES FIELD. AN UPPER LEVEL CYCLONIC CIRCULATION OVER THE WRN CARIBBEAN IS CONTRIBUTING FURTHER TO THIS MOISTURE BY ADVECTING ADDITIONAL MOISTURE FROM ONGOING CONVECTION OVER THE FAR SW CARIBBEAN SEA...AND SIMILARLY OVER NICARAGUA SWD INTO THE FAR ERN PACIFIC. THE PRES GRADIENT BETWEEN WEAK SURFACE HIGH PRES OVER SRN MEXICO AND BROAD LOW PRES ALONG AND NEAR THE ITCZ WILL INCREASE LOW TO MID-LEVEL E-SE WINDS SW OF MEXICO DURING THE NEXT FEW DAYS. AT THE SAME TIME...CROSS EQUATORIAL SLY FLOW WILL INTERACT WITH THE INCREASING E TO SE FLOW RESULTING IN AN AREA OF INCREASED LOW-LEVEL CYCLONIC VORTICITY WELL OFF THE MEXICAN COAST DURING THE NEXT 48 HOURS LEADING TO GENESIS OF SURFACE LOW PRES JUST N OF THE ITCZ IN THE VICINITY OF 103W-105W. CURRENTLY...A SURFACE TROUGH IS ANALYZED ALONG 96W FROM 7N-12N MOVING W 13 KT. THE LOW COULD POSSIBLY FORM ON THE TROUGH AS IT TRACKS WESTWARD OVER THE NEXT FEW DAYS. THE QUIKSCAT PASS FROM THIS MORNING SHOWED BROAD CYCLONIC TURNING IN THE BOUNDARY LAYER CUMULUS FIELD... AND ALONG WITH SATELLITE IMAGERY DEPICTS THE TROUGH AS PART OF THE BROAD AREA OF DISORGANIZED DISTURBED WEATHER TIED TO THE TROPICAL WAVE DESCRIBED ABOVE. WINDS OF 20-25 KT ARE EXPECTED TO OCCUR WITHIN 240 NM NE SEMICIRCLE OF THE LOW BY 48 HOURS DUE TO THE RESULTANT PRES GRADIENT BETWEEN THE LOW AND THE SURFACE RIDGE OVER MEXICO. AT THE SAME TIME...CROSS EQUATORIAL FLOW IS BRINGING SE TO S WINDS TO 20 KT S OF 5N BETWEEN 90W AND 105W...WITH THIS AREA LIKELY EXPANDING NORTHWARD DURING THE NEXT FEW DAYS. ALSO...MODERATE EASTERLY LOW/MID-LEVEL FLOW S OF THE AFOREMENTIONED RIDGE OVER THE W CARIBBEAN WILL BLEED INTO THE GULF OF PAPAGAYO...WITH SURFACE WINDS BEING ACCELERATED INTO THE 20-30 KT RANGE NEAR AND DOWNSTREAM OF THE GULF OF PAPAGAYO BY EARLY SATURDAY DUE TO VARIATIONS IN LOCAL TOPOGRAPHY. THESE WINDS WILL BE MAXIMIZED LATE AT NIGHT WHEN NOCTURNAL DRAINAGE FLOW IS AT ITS PEAK. STRONG SOUTHERN HEMISPHERIC STORMS ARE ALSO SENDING LONG-PERIOD SOUTHWESTERLY SWELL NORTHWARD...WITH WAVE HEIGHTS OF 8 TO 10 FT COVERING A LARGE PART OF THE AREA S OF 15N E OF 116W BY LATE SUNDAY...BRINGING LARGE BATTERING WAVES TO THE SW COAST OF MEXICO BY LATE IN THE WEEKEND. $$ AGUIRRE