000
AXPZ20 KNHC 032215 CCA
TWDEP 

TROPICAL WEATHER DISCUSSION...CORRECTED
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI JUL 03 2009

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN
FROM THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2115 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE HAS ENTERED THE FAR ERN PACIFIC PRESENTLY
ALONG 81W N OF 3N MOVING W AT 13 KT. CONVECTION ASSOCIATED
WITH THE WAVE IS MOST ACTIVE ALONG THE COAST OF CENTRAL PANAMA 
WHERE SCATTERED STRONG CONVECTION IS WITHIN 30 NM OF 7.5N81.5W.
WITH THE WAVE BEING UNDER A SLIGHTLY UPPER DIFFLUENT ZONE EXPECT
CONVECTION TO BECOME MORE ACTIVE ALONG AND NEAR THE WAVE DURING
THE NIGHT.

A TROPICAL WAVE EXTENDS ALONG 110W FROM 4N TO 15N MOVING W 10-15 
KT. LATEST VISIBLE SATELLITE IMAGERY SHOWS A SMALL CYCLONIC 
SWIRL OF LOW CLOUDS NEAR 13N110W. CONVECTION CONTINUES TO BE
CONFINED TO WHERE THE WAVE INTERSECTS THE ITCZ. 

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N82W 9N95W 9N110W 9N120W 7N130W
5N140W. SCATTERED MODERATE CONVECTION IS OCCURRING FROM 2N-7N
BETWEEN 81W-93W...AND WITHIN 120 NM S OF THE AXIS BETWEEN 
111W-120W.

...DISCUSSION...

A WELL PRONOUNCED MID/UPPER LEVEL WARM CORE 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 
FEATURES. THIS 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 W OF A LINE FROM 23N109W TO 16N120W TO 8N130W IS 
UNDER MODERATE SUBSIDENCE PROVIDING 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 102W 
FROM 5N-15N MOVING W 13 KT. THIS IS MOST PROBABLE THE 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 EARLY SAT 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 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-118W IN 48 HRS...AND
MAY IMPACT THE SW COAST OF MEXICO BEGINNING ON SUN AS LARGE
BATTERING WAVES.

$$
AGUIRRE