000
AXPZ20 KNHC 140336
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE APR 14 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
0315 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N78W 5N81W 6N890W 7N101W 6N112W
6N123W 7N129W 5N140W. SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION EXISTS FROM 4N-8N BETWEEN 85W-88W...AND WITHIN 90 NM
OF THE AXIS BETWEEN 122W-125W. SCATTERED MODERATE CONVECTION
CONVECTION IS WITHIN 60 NM OF THE AXIS BETWEEN 118W-120W.

...DISCUSSION...

A MID/UPPER TROUGH IS EXITING THE AREA JUST E OF THE AREA OVER 
CENTRAL MEXICO. CONFLUENT FLOW IN ITS WAKE IS RESULTING IN
AN AREA OF MODERATE SUBSIDENCE WITH STABLE ENVIRONMENTAL 
CONDITIONS FROM 16N-24N AND E OF 120W. BEHIND THE TROUGH...
A DEEP LAYER RIDGING MOVING E EXTENDS ALONG 115W N OF 20N.
TO THE W OF THE RIDGE...A SHORTWAVE TROUGH IS MOVING RAPIDLY E 
ALONG 32N128W TO 25N125W. THIS TROUGH WILL PLAY IN A MAJOR ROLE
WITH RESPECT TO THE MARINE CONDITIONS IN THE NE PART OF THE AREA 
IN THE NEXT 24-48 HRS AS IT BECOMES IN PHASE WITH A DEEPENING 
UPPER LEVEL TROUGH THAT DIGS SEWD FROM THE PACIFIC NW ACROSS THE 
WRN U.S. WITH UPPER LEVEL DYNAMICS BECOMING SUPPORTIVE OF A 
STRONG SURGE OF NWLY FLOW THROUGHOUT THE ATMOSPHERE WITH IMPACTS 
TO SURFACE WINDS...MORE ON THIS IN PARAGRAPH BELOW. THE TROUGH 
CONTINUES TO PULL AWAY FROM FURTHER INLAND BEYOND 48 HRS.

TO THE S OF THE TROUGH AND RIDGE...MID/UPPER LEVEL TROUGHING 
EXTENDS FROM 15N121W TO 10N120W TO 2N126W TO S OF THE EQUATOR AT 
125W. TO THE W OF THIS TROUGH...BROAD MID/UPPER LEVEL RIDGING 
COVERS THE AREA WITH A NEARLY STATIONARY ASSOCIATED UPPER LEVEL 
ANTICYCLONE NEAR 9.5N135W. UPPER LEVEL MOISTURE FROM THE DEEP 
TROPICAL CENTRAL PACIFIC IS STREAMING ENE UP ACROSS THE AREA OF 
BROAD MID/UPPER LEVEL RIDGING VIA A JET STREAM BRANCH THAT 
ENTERS THE REGION AT 22N140W AND STRETCHES THROUGH 22N130W NE TO 
26N122W TO ACROSS THE AXIS OF DEEP LAYER RIDGING ALONG 115W. THE 
MOISTURE PLUME IN THE FORM OF SCATTERED TO BROKEN CIRRUS CLOUDS 
SPREADS TO ACROSS NRN BAJA CALIFORNIA AND THE SW U.S. 

OVER THE SE PORTION OF THE AREA...BROAD UPPER RIDGING IS PRESENT
WITH A MEAN RIDGE AXIS ALONG 9N E OF 112W AND AN ASSOCIATED 
ANTICYCLONE OVER PANAMA. THIS FEATURE IS MAINTAINING RATHER 
STABLE CONDITIONS THROUGHOUT THIS PORTION OF THE AREA. 

AT THE SURFACE...A RIDGE EXTENDS SE THROUGH 28N133W TO 22N125W
TO NEAR 18N112W. HIGH PRES COVERS THE AREA N OF 12N W OF 112W. 
LATEST VISIBLE SATELLITE IMAGERY SHOWS A WEAK TROUGH ALONG 101W 
FROM 3N-9N MOVING W ABOUT 10 KT. ONLY ISOLATED SHOWERS ARE 
WITHIN 30 NM OF THE TROUGH.

OVER THE MARINE ENVIRONMENT...NW-N WINDS 20 KT N OF 26N BETWEEN 
120W-127W WITH SEAS 8 TO 10 FT IN N SWELL WILL INCREASE TO 20-30 
KT IN 24 HRS...AND DECREASE TO 20-25 KT WITH SEAS BUILDING TO 
11-18 FT IN NW SWELL IN 48 HRS AS SEEN IN LATEST WAVEWATCH MODEL 
GUIDANCE DUE TO THE RESULTANT TIGHT PRES GRADIENT OVER THE FAR 
NE PART OF THE AREA CREATED BY THE INTERACTIONS OF LOW PRES OVER 
THE SW U.S. FROM THE UPPER TROUGH...AND STRONG HIGH PRES NW OF 
OF THE AREA THAT TRACKS SSE CLOSE TO NEAR 32N131W. THE SAME 
GRADIENT IS PRODUCING GALE FORCE WINDS TO 35 KT JUST N OF THE NE 
WATERS. THESE WINDS ARE FORECAST THROUGH THE NEXT 48 HRS WITH 
HIGH SEAS CONTINUING TO MIGRATE S TOWARDS THE NE WATERS IN THE 
NW SWELL TRAIN.

NE TRADES OF 20-25 KT FROM 7N-22N W OF 127W AND FROM 12N-18N 
BETWEEN 118W-127W WILL BECOME MORE ELY IN 48 HRS AS HIGH PRES
N OF THE AREA SHIFTS SSE. SEAS WITHIN THESE AREAS WILL REMAIN
ON THE 8-11 FT RANGE AND CONSISTS OF A PRIMARILY NW AND SECONDARY
NE SWELL COMPONENT MIXED WITH A SW SWELL WITH THE NE BEING THE 
PRIMARILY W OF 127W. SWELLS PERIODS ARE FORECAST TO BE 11-13 
SECONDS BETWEEN 118W-127W AND 14-16 SECONDS FROM 17N-22N W OF 
127W. THE PERIODS OF 14-16 SECONDS THEN MIGRATE SE TO NEAR 4N 
BETWEEN 116W-127W WITH MUCH LESS PERIODS W OF 133W AWAY FROM THE 
PRIMARY NW SWELL.

BOTH VISIBLE AND IR SATELLITE IMAGERY SHOWS SCATTERED TO BROKEN
STRATOCUMULUS CLOUDS MOVING S AND SW WITH POSSIBLE ISOLATED 
SHOWERS N OF 15N W OF 113W. THESE CLOUDS ARE BEING STEERED BY 
THE GENERAL SYNOPTIC WIND FLOW AROUND THE HIGH PRES RIDGE THAT 
EXTENDS INTO THE REGION AS DESCRIBED ABOVE.

VOLCANIC LIGHT ASH FROM THE FERNANDINA VOLCANO S OF THE AREA 
NEAR 0.4S91.5W IS FORECAST TO SPREADING TO JUST ACROSS THE 
EQUATOR
BETWEEN 91W AND 93W. THE ASH SHOULD DIMINISH IN ABOUT 36 HRS 
PROVIDED THERE ARE NO FURTHER ERUPTIONS.

$$
AGUIRRE