000
AXPZ20 KNHC 270334
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED FEB 27 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 
0115 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 05N77W TO 05N88W TO 
02N94W TO 06N108W. ITCZ AXIS WAS ANALYZED FROM 06N108W TO 
04N117W TO 06N124W THEN CONTINUES FROM 07N130W TO 06N140W. 
SCATTERED MODERATE CONVECTION WAS WITHIN 90 NM N OF THE AXIS W 
OF 130W. A TROUGH WAS ANALYZED FROM 11N122W TO 07N128W WITH 
SCATTERED MODERATE CONVECTION FOUND NEAR THE TROUGH FROM 08N TO 
13N BETWEEN 120W AND 122W AS WELL AS FROM 07N TO 09N BETWEEN 
124W AND 128W.

...DISCUSSION...
A POSITIVELY TILTED UPPER TROUGH STRETCHED FROM 32N134W 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 THROUGH THU WHILE THE UPPER JET PULLS EASTWARD ALONG 
25N-30N. PRECIPITATION WILL FOCUS MAINLY W OF 130W BY THU 
AFTERNOON AS A RESULT. 

THE 1029 MB SUBTROPICAL HIGH NEAR 33N141W EXTENDS ITS PRIMARY 
RIDGE AXIS NORTHEASTWARD TO OREGON. 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 3-4 MB OVER THE NEXT FEW DAYS. THIS WILL EXPAND THE 
AREA OF TRADE WINDS SLIGHTLY OVER WESTERN WATERS BY THU.

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-30N 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 OF MEXICO 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 THU AFTERNOON.

$$
SCHAUER