000
AXPZ20 KNHC 152123
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU MAR 15 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1945 UTC.

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

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 04N88W TO 
02N100W TO 00N104W. SCATTERED MODERATE CONVECTION LIES WITHIN 90 
NM EITHER SIDE OF AXIS E OF 103W.

...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 SAT NIGHT. CURRENTLY...A 
SURFACE TROUGH ASSOCIATED WITH THE WEAK TROUGH ALOFT LIES OVER 
NW WATERS FROM 30N129W TO 25N140W. THIS TROUGH SEPARATES THE 
1024 MB HIGH NEAR 29N123W OFF THE COAST OF BAJA CALIFORNIA NORTE 
FROM STRONGER 1027 MB SUBTROPICAL HIGH N OF HAWAII NEAR 30N157W. 
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 THE 1810 UTC ASCAT PASS. 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 WESTWARD AND STRENGTHEN THROUGH 
THE FORECAST PERIOD 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. THESE WINDS WILL DIMINISH SAT AS THE 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 BEGIN TO 
INCREASE SEAS OVER NW WATERS BY FRI AFTERNOON. 

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...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. NO SIGNIFICANT CHANGE IN THE SYNOPTIC 
PATTERN IS ANTICIPATED OVER THE WESTERN GULF OF MEXICO UNTIL 
EARLY SAT WHEN SURFACE RIDGING AND THE ASSOCIATED PRESSURE 
GRADIENT IS EXPECTED TO RELAX OVER SOUTHERN MEXICO AND THE 
ISTHMUS OF TEHUANTEPEC.

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 96W. THE 1626 UTC ASCAT PASS 
CAPTURED THE FAR WESTERN EDGE OF THIS AREA OF WIND WHICH IS 
EXPECTED TO CHANGE LITTLE OVER THE NEXT FEW DAYS.

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