000
AXPZ20 KNHC 262145
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE FEB 26 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2030 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 07N77W TO 07N85W TO 
04N91W TO 04N100W TO 05N105W. ITCZ AXIS WAS ANALYZED FROM 
05N105W TO 05N110W TO 03N118W 06N123W THEN CONTINUES FROM 
06N127W TO 06N140W. SCATTERED MODERATE CONVECTION WAS WITHIN 120 
NM N OF THE AXIS BETWEEN 135W AND 141W. A TROUGH LIES FROM 
10N120W TO 05N126W WITH SCATTERED MODERATE CONVECTION FOUND 
WITHIN 180 NM EITHER SIDE OF THE TROUGH N OF 07N.

...DISCUSSION...
A POSITIVELY TILTED UPPER TROUGH STRETCHED FROM 32N136W TO 
10N150W HAS A 120 KT SOUTHWESTERLY UPPER JET AHEAD OF IT 
DIRECTING MOISTURE FROM THE ITCZ OVER WESTERN WATERS 
NORTHEASTWARD. PRECIPITABLE WATER IMAGERY SHOWS MID- TO 
LOW-LEVEL MOISTURE IS ABUNDANT S OF 20N. SCATTERED SHOWERS AND 
ISOLATED THUNDERSTORMS ARE MOST LIKELY TO LIE IN THIS SOUTHERN 
PORTION OF THE SWATH...INCLUDING THE REGION DESCRIBED IN THE 
SECTION ABOVE...WITH MAINLY CIRRUS FOUND ACROSS MUCH OF THE AREA 
N OF 20N...INCLUDING OVER THE GULF OF CALIFORNIA. THE UPPER 
TROUGH WILL WEAKEN AND CUT OFF AN UPPER LOW NEAR 20N OVER W 
WATERS DURING THE NEXT FEW DAYS WHILE THE UPPER JET PULLS 
EASTWARD ALONG 25N-30N. PRECIPITATION WILL FOCUS MAINLY W OF 
130W BY THU AFTERNOON AS A RESULT. 

THE 1031 MB SUBTROPICAL HIGH NEAR 36N132W EXTENDS ITS PRIMARY 
RIDGE AXIS NORTHEASTWARD TO THE PACIFIC NW U.S. AND 
WEST-SOUTHWESTWARD TO 34N141W. ANTICYCLONIC FLOW ASSOCIATED WITH 
THE RIDGE PREVAILS OVER MOST OF THE DISCUSSION AREA W OF 
110W...WITH FRESH NE TRADE WINDS DOMINATING THE REGION N OF THE 
ITCZ TO 15N W OF 130W ACCORDING TO THE 1804 UTC ASCAT PASS. THE 
SUBTROPICAL RIDGE WILL SHIFT 2-3 DEGREES SOUTHWARD AND THE HIGH 
WILL BUILD 2-3 MB OVER THE NEXT FEW DAYS. THIS WILL EXPAND THE 
AREA OF TRADE WINDS SLIGHTLY OVER WESTERN WATERS.

GAP WINDS...
GULF OF CALIFORNIA...THE PRESSURE GRADIENT BETWEEN HIGH PRESSURE 
OVER THE GREAT BASIN AND TROUGHING ACROSS WESTERN MEXICO HAS 
SLACKENED SLIGHTLY AT THE MOMENT. FRESH TO STRONG NW WINDS ARE 
CONFINED BETWEEN 25N-28N IN THE GULF OF CALIFORNIA. HOWEVER...A 
STRONG COLD FRONT WILL SWEEP THROUGH N CENTRAL MEXICO OVERNIGHT 
TONIGHT AND HIGH PRESSURE WILL BUILD TO THE N. WINDS ARE 
EXPECTED TO INCREASE TO NEAR GALE FORCE BY WED EVENING AS THE 
PRESSURE GRADIENT TIGHTENS. SEAS WILL AGAIN BUILD OVER 8 FT ON 
WED...WITH N SWELL FROM THE GULF OF CALIFORNIA SPILLING SOUTH OF 
THE MOUTH OF THE GULF AND MIXING WITH LONG-PERIOD NW SWELL BY 
THU.  

GULF OF TEHUANTEPEC...THE 1622 UTC ASCAT PASS SHOWED N WINDS TO 
30 KT NEAR THE COAST IN THE GULF OF TEHUANTEPEC. THIS BURST OF 
GAP WINDS IS EXPECTED TO DIMINISH WED MORNING AS THE RIDGE IN 
THE GULF OF MEXICO SHIFTS EASTWARD...TURNING WINDS IN THE SW 
GULF OF MEXICO SOUTHEASTERLY AND CUTTING OFF THE FLOW THROUGH 
CHIVELA PASS. A NEW SURGE OF NORTHERLY WINDS WILL MOVE THROUGH 
THE GULF OVERNIGHT WED NIGHT...WITH FRESH TO STRONG N WINDS 
MAKING THEIR WAY INTO THE GULF OF TEHUANTEPEC BY THU 
MORNING...INCREASING TO NEAR GALE FORCE BY THE AFTERNOON.

$$
SCHAUER