000
AXPZ20 KNHC 252128
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SUN MAR 25 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 
2100 UTC.

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

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N120W TO 
06N130W TO 06N140W. NO SIGNIFICANT CONVECTION IS NOTED.

...DISCUSSION...

AN AMPLIFIED UPPER LEVEL TROUGH N OF 20N ALONG 120W WILL ACQUIRE 
A NEGATIVE TILT WHILE MOVING INTO THE WESTERN U.S. AND NW MEXICO 
THROUGH MON. A 70-90 KT NORTHERN STREAM UPPER JET ROUNDS THE 
TROUGH NEAR 30N WHILE THE SOUTHERN STREAM JET EXTENDS ZONALLY 
BETWEEN 05N AND 20N TO THE BASE OF THE TROUGH NEAR 120W. A BAND 
OF HIGH LEVEL MOISTURE IS BEING ADVECTED TO THE NE AHEAD OF THE 
TROUGH FROM 20N120W TO ACROSS THE NORTHERN GULF OF CALIFORNIA. A 
SECOND BAND OF MOISTURE LIES FROM 10N-20N W OF 120W ASSOCIATED 
WITH THE SOUTHERN STREAM JET. MODERATE TO STRONG SUBSIDENCE WITH 
DRY AIR IN THE MID-UPPER LEVELS IS N OF 20N W OF 120W. ELSEWHERE 
A BROAD UPPER LEVEL RIDGE IS CENTERED FROM CENTRAL TEXAS THROUGH 
MEXICO TO 10N102W. THIS RIDGE WILL SHIFT E AHEAD OF THE 
NEGATIVELY TILTED TROUGH MON THROUGH TUE.

THE AFOREMENTIONED UPPER LEVEL TROUGH IS SUPPORTING A SURFACE 
COLD FRONT OVER THE N WATERS FROM 30N118W TO 24N124W TO 21N134W. 
W TO NW WINDS HAVE INCREASED TO GALE FORCE BEHIND THE FRONT NEAR 
32N132W ACCORDING TO AN EARLIER ASCAT SCATTEROMETER PASS AS A 
SURFACE LOW MAKES ITS CLOSEST APPROACH TO THE FORECAST AREA. THE 
1008 MB SURFACE LOW CURRENTLY LIES NEAR 34N123W. GALE FORCE 
WINDS WITH THIS LOW ARE STILL EXPECTED TO REMAIN N OF 30N. A 
SURFACE TROUGH EXTENDS FROM THE LOW THROUGH 30N121W TO 27N130W 
WITH FRESH TO STRONG WINDS N OF 27N BETWEEN 120W AND 130W. THESE 
WINDS WILL QUICKLY DIMINISH LATE TONIGHT THROUGH MON AS THE 
SUPPORTING TROUGHING ALOFT ACQUIRES ITS NEGATIVE TILT ALLOWING 
FOR RIDGING TO BUILD TO ITS SOUTH...AND THUS BREAKING UP THE 
DEEP LAYER TROUGHING. THE FRONT WILL WEAKEN SHARPLY BEFORE 
DISSIPATING OVER THE FORECAST WATERS BY MON AFTERNOON. LARGE NW 
SWELL UP TO 20 FT CURRENTLY LIES W OF THE FRONT. THE LARGE NW 
SWELL WILL GRADUALLY DECAY TO 8-12 FT BY MON AFTERNOON AND THEN 
TO 8-11 FT BY TUE AFTERNOON AS IT CONTINUES TO PROPAGATE TO THE 
SE.

FRESH TRADE WINDS...WHICH HAVE TAKEN A HIATUS DUE TO THE FRONT 
BREAKING UP THE SUBTROPICAL RIDGE TO THE N...WILL RETURN BY MON 
AFTERNOON AS HIGH PRES BUILDS E BEHIND THE FRONT. THE WEAK HIGH 
WILL LIE OVER THE NE WATERS BY TUE MORNING...FORCED EASTWARD BY 
ANOTHER COLD FRONT MOVING INTO THE NW WATERS.

FARTHER S...A PERSISTENT SURFACE TROUGH LIES FROM 09N86W TO 
04N91W TO 03N99W. SCATTERED MODERATE AND ISOLATED STRONG 
CONVECTION CAN BE FOUND WITHIN 180 NM S OF THE TROUGH BETWEEN 
90W AND 96W. MOSITURE POOLED SOUTH OF THE SURFACE TROUGH IS 
BEING LIFTED BY UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THE REAR 
RIGHT QUADRANT OF THE UPPER JET OVER THE CARIBBEAN. 

GAP WINDS...
GULF OF CALIFORNIA...FRESH TO STRONG S-SW WINDS LIE IN THE FAR 
NORTHERN GULF OF CALIFORNIA N OF 30N. THESE WINDS ARE FORECAST 
TO CONTINUE THROUGH MON MORNING AHEAD OF THE WEAKENING COLD 
FRONT CURRENTLY APPROACHING THE BAJA CALIFORNIA PENINSULA.

$$
LEWITSKY