000 AXPZ20 KNHC 040318 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SAT JUL 04 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 0300 UTC. ...TROPICAL WAVES... A TROPICAL WAVE OVER THE FAR ERN PACIFIC IS ALONG 82W N OF 6N MOVING W AT 15 KT. CONVECTION ASSOCIATED WITH THE WAVE IS MOST ACTIVE ALONG AND INLAND THE COAST OF COSTA RICA AND PANAMA WHERE SCATTERED STRONG CONVECTION IS IDENTIFIED. WITH THE WAVE BEING UNDER A SLIGHTLY UPPER DIFFLUENT ZONE EXPECT CONVECTION TO INCREASE OVERNIGHT INTO SAT MORNING. A TROPICAL WAVE EXTENDS ALONG 115W FROM 8N TO 15N MOVING W 10-15 KT. ONLY ISOLATED SHOWERS ARE WITHIN 60 NM E OF THE WAVE. CONVECTION CONTINUES TO BE CONFINED TO WHERE THE WAVE INTERSECTS THE ITCZ. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 9N84W 10N95W 13N104W 12N115W 9N130W 65N140W. SCATTERED STRONG CONVECTION IS OCCURRING WITHIN 240 NM S OF THE AXIS BETWEEN 81W-87W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM S OF THE AXIS BETWEEN 108W-119W. ...DISCUSSION... A WELL PRONOUNCED MID/UPPER LEVEL ANTICYCLONE IS OVER SW TEXAS WITH A RIDGE EXTENDING SW TO ACROSS CENTRAL BAJA CALIFORNIA TO 23N121W TO 21N130W AND TO SW OF THE AREA AT 14N140W. A LARGE DEEP LAYER TROUGH IS WELL W OF THE REGION. A PERSISTENT UPPER LEVEL SW FLOW PATTERN IS OBSERVED BETWEEN THESE TWO FEATURES... AND CONTINUES TO ADVECT DEEP TROPICAL UPPER LEVEL MOSITURE FROM THE CENTRAL PACIFIC NEWD INTO THE AREA FROM 21N TO 27N E TO NEAR 130W. A SWATH OF UPPER LEVEL MOISTURE JUST GRAZES THE FAR NW CORNER OF THE AREA AHEAD OF THE TROUGH. OTHERWISE...SATELLITE WATER VAPOR IMAGERY SHOWS THAT THE VAST MAJORITY OF THE DISCUSSION AREA W OF A LINE FROM 23N109W TO 16N120W TO 8N130W IS UNDER MODERATE SUBSIDENCE RESULTING IN RATHER STABLE ENVIRONMENTAL CONDITIONS AS INDICATED BY THE PRESENCE OF PATCHES OF SCATTERED TO BROKEN STRATOCUMULUS CLOUDS MOVING S AROUND THE ERN PERIPHERY OF WEAK SURFACE HIGH PRESSURE PRESENT N OF 15N W OF 120W. A LAYER OF BROKEN STRATOCUMULUS CLOUDS IS ERODING OVER THE FAR NE PART OF THE AREA N OF 19N E OF 119W TO ALONG THE COAST OF BAJA CALIFORNIA. OVER THE REMAINDER OF THE AREA ABUNDANT UPPER LEVEL MOISTURE IS OBSERVED ON SATELLITE IMAGERY...PRIMARILY ATTRIBUTED TO MODERATE TO STRONG ELY SHEAR OCCURRING ON THE SRN PERIPHERY THE ANTICYCLONE OVER SW TEXAS...BUT IS ALSO BEING ENHANCED IN THE ITCZ REGION AND SURROUNDING AREAS WHICH REMAIN UNDER A BROAD LOW PRES FIELD. AN UPPER LEVEL CYCLONIC CIRCULATION OVER THE SW CARIBBEAN SEA IS CONTRIBUTING FURTHER TO THIS MOISTURE BY ADVECTING ADDITIONAL MOISTURE FROM ONGOING CONVECTION OVER THE FAR SW CARIBBEAN SEA...AND OVER CENTRAL AMERICA S OF HONDURAS SWD INTO THE FAR ERN PACIFIC. BOUNDARY LAYER WINDS CONTINUE TO BE ON THE LIGHT SIDE ACROSS THE SUBTROPICS DUE TO A STALLED FRONT NW OF THE AREA INTERRUPTING THE SUBTROPICAL RIDGING. NW 20 KT WINDS ARE FORECAST TO INCREASE OVER THE FAR NE CORNER OF THE AREA LATE SUN INTO MON AS THE SUB-TROPICAL HIGH TAKES MORE HOLD OF THE AREA...BEING THE MORE TYPICAL SCENARIO. 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 BEGINNING WITHIN THE NEXT 36-48 HOURS. THIS IS EXPECTED TO LEAD TO GENESIS OF SURFACE LOW PRES IN THE VICINITY 13N105W...AND TO NEAR 15N109W BY 48 HOURS. A SURFACE TROUGH IS CURRENTLY ANALYZED ALONG 103W FROM 5N-8N MOVING W 13 KT. THIS IS THE MOST PROBABLE FEATURE THAT LENDS TO GENESIS OF THE FORECAST LOW. A PARTIAL QUIKSCAT PASS FROM THIS MORNING AGAIN 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 THAT MAY EVENTUALLY CONSOLIDATE TO FORM THE FORECAST LOW. WINDS OF 20-25 KT ARE FORECAST IN THE NE QUADRANT OF THE LOW WITHIN A DISTANCE OF ABOUT 180 NM TO 300 NM DUE TO THE RESULTANT PRES GRADIENT BETWEEN THE LOW AND THE GEOGRAPHIC INFLUENCE OF THE MEXICAN COAST. LATEST WAVEWATCH GUIDANCE SHOWS SEAS BUILDING TO 8-10 FT IN THE NE QUADRANT OF THE LOW BY 48 HOURS. CROSS EQUATORIAL FLOW IS BRINGING SE TO S WINDS TO 20 KT FROM 2N TO 8N BETWEEN 105W AND 125W...AND S OF 6N W OF 134W. ALSO... MODERATE EASTERLY LOW/MID-LEVEL FLOW OVER THE W CARIBBEAN WILL BLEED INTO THE GULF OF PAPAGAYO...WITH SURFACE WINDS BEING ACCELERATED INTO THE 20-25 KT RANGE NEAR AND DOWNSTREAM OF THE GULF OF PAPAGAYO OVERNIGHT INTO SAT DUE TO VARIATIONS IN LOCAL TOPOGRAPHY. THESE WINDS WILL BE MAXIMIZED LATE AT NIGHT WHEN NOCTURNAL DRAINAGE FLOW IS AT ITS PEAK...AND ARE FORECAST TO DIMINISH LATE SUN. STRONG SOUTHERN HEMISPHERIC FRONTAL SYSTEMS CONTINUE TO SEND LONG-PERIOD SWLY SWELLS NWD WITH PERIODS OF 15-17 SECONDS WITH SEAS IN THE 8-10 FT RANGE FROM 2N TO 8N BETWEEN 105 AND 125W. THESE SEAS ARE EXPECTED TO BE WITHIN THE AREA S OF 5N BETWEEN 94W-115W IN 48 HRS...AND MAY IMPACT THE SW COAST OF MEXICO BEGINNING ON SUN AS LARGE BATTERING WAVES. $$ AGUIRRE