000
AXPZ20 KNHC 160315
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI MAR 16 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 05N85W TO 
03N97W TO 00N104W. SCATTERED MODERATE ISOLATED STRONG CONVECTION 
LIES WITHIN 90 NM S OF THE AXIS BETWEEN 88W AND 91W.

...DISCUSSION...

THE WEAK UPPER LEVEL TROUGH STRETCHED NE TO SW ACROSS THE 
FORECAST AREA N OF 10N WILL BEGIN TO PHASE WITH AN AMPLIFYING 
NORTHERN STREAM TROUGH BEGINNING FRI NIGHT. CURRENTLY...A 
SURFACE TROUGH ASSOCIATED WITH THE WEAK TROUGH ALOFT LIES OVER 
NW WATERS FROM 30N128W TO 27N133W TO 26N138W. THIS TROUGH 
SEPARATES THE 1023 MB HIGH NEAR 30N122W OFF THE COAST OF BAJA 
CALIFORNIA NORTE FROM A 1030 MB SUBTROPICAL HIGH N OF HAWAII 
NEAR 31N156W. THE ZONALLY ORIENTED SUBTROPICAL RIDGE OVER N 
WATERS IS SUPPORTING A WIDE SWATH OF FRESH TRADE WINDS FROM 07N 
TO 17N W OF 120W ACCORDING TO ASCAT AND OSCAT PASSES BETWEEN 
1800 AND 2130 UTC. AS THE AMPLIFYING NORTHERN STREAM TROUGH 
APPROACHES...THE HIGH PRES SYSTEM OFF THE BAJA WILL SHIFT 
WESTWARD AND MERGE WITH THE LARGER SUBTROPICAL HIGH. THE TRADE 
WINDS WILL SHIFT W OF 130W BY THE END OF THE FORECAST PERIOD SAT 
EVENING AS A RESULT. 

THE PRES GRADIENT BETWEEN THE HIGH OFF BAJA CALIFORNIA AND 
TROUGHING OVER NW MEXICO HAS ALLOWED FRESH NW WINDS TO SET UP 
ALONG THE W COAST OF BAJA CALIFORNIA ACCORDING TO THE 1802 UTC 
ASCAT PASS AND THE 1944 UTC OSCAT PASS. THESE WINDS WILL 
DIMINISH SAT MORNING AS THE AFOREMENTIONED DEEP LAYER TROUGH AND 
ITS ASSOCIATED COLD FRONT APPROACHES...SLACKENING THE PRES 
GRADIENT. 

THE COLD FRONT WILL MOVE INTO NORTHERN FORECAST WATERS BY SAT 
MORNING. FRESH TO STRONG NW TO N WINDS WILL BE USHERED IN BY THE 
FRONT. NW SWELL WILL PROPAGATE AHEAD OF THE SYSTEM AND INCREASE 
SEAS TO 9 FT IN NW WATERS BY FRI MORNING. SEAS ARE EXPECTED TO 
REACH AS HIGH AS 15 FEET BY THE SAT EVENING.

THE SOUTHERN STREAM UPPER JET ALONG 12N W OF 130W SPLITS AS IT 
MOVES EASTWARD...WITH THE SOUTHERN BRANCH CONTINUING ALONG 10N 
AND THE NORTHERN BRANCH DIRECTED INTO NW MEXICO...TRACKING ONTO 
THE LEADING EDGE OF THE AFOREMENTIONED WEAK UPPER TROUGH TO THE 
N. THE NORTHERN BRANCH OF THE JET IS TRANSPORTING TROPICAL 
MOISTURE IN THE MID AND UPPER LEVELS THROUGH THE SOUTHERN GULF 
OF CALIFORNIA INTO THE RIO GRANDE VALLEY. THIS MOISTURE IS 
MANIFESTED AS A BAND OF MULTI-LAYERED CLOUDS ALONG THE JET AXIS. 
THESE CONDITIONS WILL CONTINUE OVER THE NEXT TWO DAYS AS THE 
ORIENTATION OF THE NORTHERN BRANCH OF THE JET IS NOT EXPECTED TO 
CHANGE SIGNIFICANTLY.

GAP WINDS... 
GULF OF TEHUANTEPEC...THE SURFACE RIDGING AND ASSOCIATED PRES 
GRADIENT OVER SOUTHERN MEXICO AND THE ISTHMUS OF TEHUANTEPEC 
WILL GRADUALLY WEAKEN BEGINNING FRI. FRESH TO STRONG N TO NE 
WINDS IN THE GULF OF TEHUANTEPEC REGION ARE EXPECTED TO DIMINISH 
TO LESS THAN 20 KT BY SAT AFTERNOON.

GULF OF PAPAGAYO...FRESH TO STRONG TRADES ACROSS THE CARIBBEAN 
SEA CONTINUE TO FUNNEL NORTHEASTERLY GAP WINDS INTO THE GULF OF 
PAPAGAYO EXTENDING WESTWARD TO 98W. THE 1626 UTC ASCAT PASS AND 
1808 UTC OSCAT PASS CAPTURED THE FAR WESTERN EDGE OF THIS AREA 
OF WIND WHICH IS EXPECTED TO GRADUALLY SHRINK EASTWARD BEGINNING 
FRI.

GULF OF PANAMA...TRADES IN THE SW CARIBBEAN SEA WILL CONTINUE TO 
SUPPORT PULSES OF FRESH NORTHERLY FLOW ACROSS THE ISTHMUS OF 
PANAMA INTO THE GULF OF PANAMA. SEAS ARE EXPECTED TO REMAIN LESS 
THAN 8 FT WITH LITTLE CHANGE EXPECTED OVER THE NEXT 48 HOURS.

$$
SCHAUER