000
AXPZ20 KNHC 181535
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT FEB 18 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1330 UTC.

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

THE MONSOON TROUGH AXIS EXTENDS FROM 00N89W TO 06N110W TO 1009 
MB LOW PRES NEAR 05N117W TO 01N126W. THE ITCZ AXIS EXTENDS FROM 
01N126W TO BEYOND 01N140W. SCATTERED MODERATE CONVECTION IS 
WITHIN 390 NM N OF THE AXIS BETWEEN 102W AND 120W AND WITHIN 240 
NM S OF THE AXIS BETWEEN 106W AND 125W. 

...DISCUSSION...

A BROAD UPPER TROUGH EXTENDS FROM THE RIO GRANDE VALLEY NEAR 
30N104W THROUGH 15N123W TO 18N137W. THE NORTHERN PORTION OF THIS 
TROUGH IS MIGRATE EASTWARD INTO TEXAS. THIS WILL DISTANCE ITSELF 
FROM THE WEAKER TROUGHING OVER WESTERN WATERS. THE ENERGY ON THE 
WESTERN EDGE OF THIS TROUGH WILL PHASE WITH A NEW TROUGH 
DROPPING S ALONG THE CALIFORNIA COAST BY SUN. CURRENTLY...THIS 
ENERGY IS ASSOCIATED WITH A SURFACE LOW ALONG THE ITCZ NEAR 
05N117W. PRECIPITABLE WATER IMAGERY SHOWS DEEP LAYER MOISTURE IS 
POOLED S OF THE BROAD UPPER TROUGH AXIS...WITH THE MAXIMUM 
MOISTURE FOUND IN THE AREA OF LOW LEVEL CONVERGENCE NEAR THE 
SURFACE LOW PRES SYSTEM. THIS LOW LIES UNDER AN AREA OF BROAD 
UPPER DIFFLUENCE BETWEEN THE NW FLOW ON THE NE SIDE OF AN 
ANTICYCLONE CENTERED NEAR 09S137W AND SW FLOW ON THE SOUTHERN 
EDGE OF THE BROAD UPPER TROUGH. THIS DIFFLUENCE IS ENHANCING 
SCATTERED MODERATE CONVECTION NEAR THE MONSOON TROUGH. THIS 
CONVECTION IS DESCRIBED IN THE ITCZ/MONSOON TROUGH SECTION 
ABOVE. 

THE SURFACE RIDGE AXIS EXTENDING FROM 1034 MB HIGH PRES CENTERED 
NEAR 35N143W SOUTHEASTWARD TO NEAR 15N100W IS DICTATING THE 
PREVAILING FRESH TO STRONG NORTHEASTERLY WINDS ACROSS MUCH OF 
THE AREA BETWEEN THE RIDGE AND THE ITCZ/MONSOON TROUGH. THE 0430 
UTC ASCAT PASS SHOWS FRESH NE WINDS EXTEND EASTWARD TO THE AREA 
N OF THE SURFACE LOW ALONG THE MONSOON TROUGH WHILE FRESH NW TO 
N WINDS LIE JUST N OF THE RIDGE AXIS NEAR THE COAST OF CABO 
CORRIENTES MEXICO. THE 0730 UTC OSCAT PASS ALSO SHOWS FRESH NW 
WINDS IN THE SOUTHERN PORTION OF THE GULF OF CALIFORNIA. THESE 
WINDS NEAR THE MEXICO COAST WILL GRADUALLY DIMINISH THROUGH SUN 
MORNING AS SURFACE TROUGHING ASSOCIATED WITH A COLD FRONT OVER 
NE MEXICO WEAKENS WHEN THE FRONT PASSES E INTO THE GULF OF 
MEXICO. 

THE NEW UPPER TROUGH WILL DROP S ALONG THE SOUTHERN CALIFORNIA 
COAST OVERNIGHT TONIGHT. N WINDS HAVE ALREADY BEGUN TO INCREASE 
OVER NE WATERS AND LARGER NW SWELL IS MOVING INTO THE FORECAST 
AREA. SOUTHWESTERLY WINDS WILL BRIEFLY INCREASE TO FRESH OVER 
THE NORTHERN GULF OF CALIFORNIA AHEAD OF THE SURFACE REFLECTION 
OF THIS TROUGH SUN MORNING.  

...GAP WINDS...

GULF OF TEHUANTEPEC...EXPECT INCREASING WINDS AND SEAS ACROSS 
THE GULF OF TEHUANTEPEC BY SUN AFTERNOON AS A STRONG...BUT FAST 
MOVING...COLD FRONT MOVES THROUGH CHIVELA PASS. THE NORTHERLY 
WINDS THROUGH THE PASS INTO THE GULF OF TEHUANTEPEC ARE FORECAST 
TO BRIEFLY REACH GALE FORCE OVERNIGHT SUN NIGHT BEFORE 
DIMINISHING BELOW GALE BY SUNRISE ON MON.

GULF OF PAPAGAYO...NE TO E WINDS WILL CONTINUE TO PULSE TO 20 KT 
THROUGH THE GULF OF PAPAGAYO THROUGH MON MORNING. THE STRONGEST 
WINDS WILL OCCUR DURING THE EARLY MORNING HOURS WITH THE AID OF 
DRAINAGE FLOW. 

THE NORTHERLY WINDS OF 20 KT THAT WERE PASSING INTO THE GULF OF 
PANAMA YESTERDAY APPEAR TO BE GRADUALLY DIMINISHING...WITH THE 
0308 UTC ASCAT PASS ONLY SHOWING ONE BARB OF 20 KT WINDS IN THE 
AREA. 
 
$$
SCHAUER