000
AXPZ20 KNHC 280324
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU FEB 28 2013

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 
0100 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 04N77W TO 05N85W TO 
02N95W TO 02N107W. ITCZ AXIS WAS ANALYZED FROM 02N107W TO 
04N115W TO 03N121W TO 03N130W TO 00N140W. SCATTERED MODERATE 
CONVECTION WAS WITHIN 120 NM N OF THE AXIS BETWEEN 84W AND 88W. 

...DISCUSSION...

STRONG HIGH PRES BUILDING SOUTHWARD BEHIND A COLD FRONT MOVING 
THROUGH THE GULF OF MEXICO WILL TIGHTEN THE PRES GRADIENT ACROSS 
SOUTHERN MEXICO. AS A RESULT...NORTHERLY WINDS WILL INCREASE TO 
A STRONG BREEZE IN THE GULF OF TEHUANTEPEC THU MORNING. THE 
GRADIENT WILL STRENGTHEN FURTHER THU...WITH MINIMAL GALE FORCE 
WINDS COMMENCING OVERNIGHT THU NIGHT. THE POTENTIAL EXISTS FOR 
STORM FORCE WINDS BY LATE SAT INTO SUN.  

THE PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER THE GREAT BASIN 
AND TROUGHING ACROSS WESTERN MEXICO HAS INDUCED STRONG TO NEAR 
GALE FORCE NW WINDS ALONG THE LENGTH OF THE GULF OF CALIFORNIA. 
THE EARLIER 1740 UTC ASCAT PASS CAPTURED THE FRESH TO STRONG 
BREEZE IN THE GULF...WITH THE STRONGEST WINDS PRIMARILY HUGGING 
THE EAST COAST OF BAJA CALIFORNIA. WINDS HERE SHOULD HAVE 
INCREASED TO NEAR GALE FORCE THIS EVENING AS THE PRESSURE 
GRADIENT TIGHTENED FURTHER. SEAS WILL BUILD TO 10-11 FT IN THE 
GULF OF CALIFORNIA BY THU...WITH N SWELL FROM THE GULF SPILLING 
SOUTH OF THE MOUTH OF THE GULF AND MIXING WITH LONG-PERIOD NW 
SWELL. 

A POSITIVELY TILTED UPPER TROUGH STRETCHED FROM 32N130W TO 
22N140W IS BEGINNING TO PINCH OFF AN UPPER LOW W OF THE AREA 
NEAR 14N144W ACCORDING TO WATER VAPOR IMAGERY. A 120-140 KT 
SOUTHWESTERLY UPPER JET AHEAD OF THE TROUGH IS DIRECTING 
MOISTURE FROM THE ITCZ W OF THE AREA OVER MUCH OF THE REGION N 
OF A LINE FROM 10N140W TO THE BAJA CALIFORNIA PENINSULA ALONG 
25N. PRECIPITABLE WATER IMAGERY SHOWS MID- TO LOW-LEVEL MOISTURE 
IS ABUNDANT S OF 22N. SCATTERED SHOWERS AND ISOLATED 
THUNDERSTORMS ARE MOST LIKELY TO LIE IN THIS SOUTHERN PORTION OF 
THE MOISTURE SWATH WITH MAINLY CIRRUS FOUND ACROSS MUCH OF THIS 
AREA N OF 22N. THE UPPER TROUGH WILL WEAKEN AS IT CUTS OFF THE 
UPPER LOW WHICH WILL MERGE WITH A NEW NORTHERN STREAM TROUGH 
APPROACHING FROM THE NW FRI THAT WILL OPEN UP THE LOW AND TURN 
WHAT IS LEFT OF IT NEGATIVE TILT OVER WESTERN WATERS. 
PRECIPITATION SHOULD GRADUALLY SHIFT WEST OF 130W THROUGH THU 
NIGHT AND REMAIN THERE FRI.

THE 1031 MB SUBTROPICAL HIGH NEAR 34N132W EXTENDS ITS PRIMARY 
RIDGE AXIS SOUTHWESTWARD TO 32N140W. ANTICYCLONIC FLOW 
ASSOCIATED WITH THE RIDGE PREVAILS OVER MOST OF THE DISCUSSION 
AREA W OF 115W...WITH FRESH TO STRONG NE TRADE WINDS DOMINATING 
THE REGION FROM 10N-27N W OF 127W. THE SUBTROPICAL RIDGE WILL 
STRENGTHEN SLIGHTLY TOMORROW BEFORE SHIFTING NORTHEASTWARD AHEAD 
OF A COLD FRONT WELL N OF THE AREA. THE TRADE WINDS WILL SHRINK 
WESTWARD BY FRI AS A RESULT OF THE WEAKENING SUBTROPICAL RIDGE 
AND FOCUSING CLOSE TO THE SURFACE REFLECTION OF THE 
AFOREMENTIONED UPPER LOW/TROUGH OVER WESTERN WATERS ON FRI.

$$
SCHAUER