000
AXPZ20 KNHC 120336
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT MAR 12 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0230 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS ANALYZED 08N81W TO 
05N83W TO 02N95W TO 06N113W TO 07N125W TO 05N140W. SCATTERED 
MODERATE CONVECTION WAS NOTED WITHIN 150 NM EITHER SIDE OF AXIS 
BETWEEN 114W AND 122W. SCATTERED MODERATE CONVECTION NOTED 
WITHIN 90 NM OF AXIS BETWEEN 83W AND 93W. SCATTERED MODERATE TO 
STRONG CONVECTION WAS NOTED WITHIN 90 NM S AND 150 NM N OF AXIS 
W OF 116W.

...DISCUSSION...

A BROAD AND RELATIVELY  FLAT TROPICAL UPPER RIDGE PERSISTS OVER 
THE MAJORITY OF THE AREA FROM JUST N OF THE EQUATOR TO NEAR 20N 
BETWEEN 90W AND 140W...WITH E PORTIONS CENTERED ON AN UPPER 
ANTICYCLONE NEAR 110N112W....WHILE W PORTIONS OF THE RIDGE ARE 
RESULTANT OF UPPER DIVERGENCE INDUCED FROM DEEP ITCZ CONVECTION 
PREVAILING W OF 125W. AN EQUATORIAL UPPER TROUGH WAS NOTED 
MEANDERING ALONG THE EQUATOR E OF 140W...ANCHORED ON AN UPPER 
CYCLONE JUST S OF THE ITCZ NEAR 02N130W. SUBSIDENCE DOMINATES 
THE AREA N OF 10N E OF 110W. OTHERWISE...AN ENERGETIC AND 
PROGRESSIVE W- TO SW FLOW PREVAILS ALOFT NW OF THE RIDGING AND 
ITCZ...AND CONTINUES TO TRANSPORT ABUNDANT MOISTURE FROM THE 
CENTRAL TROPICAL PACIFIC S OF THE HAWAIIAN ISLANDS TO THE CREST 
AND OVER THE TOP OF THE RIDGE TO ACROSS BAJA CALIFORNIA...NW 
MEXICO AND THE SW U.S. WEAK SHORTWAVE TROUGHS ARE NOTED IN THIS 
W-SW FLOW WITH LITTLE IMPACT GENERATED BY THEM.

UPSTREAM...A STRONG AND DYNAMIC UPPER TROUGH WAS SWEEPING ACROSS 
THE N CENTRAL PACIFIC AND ENTERING THE NE PACIFIC...REACHING SW 
ACROSS THE FAR NW CORNER OF THE AREA THROUGH 30N138W TO JUST SE 
OF THE BIG ISLAND OF HAWAII AND BEYOND. THIS DEEP LAYERED TROUGH 
IS SUPPORTING A STRONG COLD FRONT NW OF THE AREA THAT WILL BE 
SWEEPING JUST NW OF THE AREA SAT...WITH A SECOND REINFORCING 
FRONT TO ENTER NW PORTIONS SUN. NW SWELL FROM A PREVIOUS FRONTAL 
SYSTEM HAS RISEN SEAS 9 TO 12 FT IN THE NW PORTION WHICH WILL 
GRADUALLY DECAY AS IT CONTINUES TO PROPAGATE SE DURING THE NEXT 
24 HOURS. ADDITIONAL PULSES OF EVEN LARGER NW SWELL WILL ARRIVE 
LATE SUN THROUGH EARLY NEXT WEEK.

ELSEWHERE AT THE SURFACE...A 1023 MB HIGH PRES IS POSITIONED 
NEAR 29N130W WITH RIDGING EXTENDING SE FROM THE HIGH TO NEAR 
20N110W. THE ASSOCIATED UPPER LEVEL RIDGING E OF 130W CONTINUES 
TO BLOCK FRONTAL SYSTEMS FROM ENTERING THE AREA FROM THE W AND 
NW. AS THE NEXT ABOVE MENTIONED FRONTAL SYSTEM APPROACHES THE 
AREA THE HIGH WILL BE NUDGED E-SE...INCREASING THE PRES GRADIENT 
BETWEEN THE HIGH PRES AND LOWER PRES E OF THE U.S. ROCKY 
MOUNTAINS AND THE SIERRA MADRE OCCIDENTALS. THIS HAS ALREADY  
RESULTED IN NW-N 20 KT WINDS OFF N PORTIONS OF THE W COAST OF 
BAJA CALIFORNIA THIS EVENING AND WILL GRADUALLY INCREASE TO 20 
TO 25 KT THROUGH SUN EVENING.

THIS SLOWLY SHIFTING SURFACE HIGH HAS WEAKENED THE PRES GRADIENT 
N OF THE ITCZ...WHICH IS LIMITING FRESH TRADE WINDS IN A NARROW 
ZONE N OF THE ITCZ TO 13N W OF 121W. THIS NARROW AREA OF 20 KT 
TRADE WINDS IS EXPECTED TO SHIFT SLOWLY WWD THROUGH SUN EVENING 
TO W OF 128W...THEN BECOME REINVIGORATED LATE MON INTO TUE AS 
THE NEXT FRONT MOVES INTO NW PORTIONS.

GAP WINDS...
GULF OF TEHUANTEPEC...STRONG NORTHERLY WINDS CONTINUE TO SURGE 
THROUGH THE GULF OF TEHUANTEPEC...BUT HAVE FALLEN BELOW GALE 
FORCE LATE THIS EVENING. LATEST WAVE MODEL GUIDANCE SUGGESTS 
SEAS UP TO 14 FT WITHIN THIS PLUME OF STRONG WINDS. WINDS WILL 
DIMINISH TO LESS THAN 20 KT BY 12Z SUN. NE SWELL GENERATED BY 
THESE WINDS WILL PROPAGATE SW REACHING ALL THE WAY TO THE 
EQUATOR BY SAT EVENING.

GULF OF PAPAGAYO...HIGH PRES SHIFTING E INTO THE NE GULF OF 
MEXICO BEHIND AN OLD COLD FRONT HAS SHIFTED WINDS TO THE NE 
ACROSS MUCH OF THE W CARIBBEAN...AND NELY GAP WIND FLOW HAS 
BEGUN TO FUNNEL THROUGH THE PASSES OF SOUTHERN NICARAGUA AND 
NORTHERN COSTA RICA. FRESH NE-E WINDS ARE EXPECTED ACROSS THE 
GULF OF PAPAGAYO AND DOWNWIND TO 89W SAT WITH WINDS INCREASING 
TO 20-25 KT AND EXPANDING TO 91W. WINDS AREA EXPECTED TO WEAKEN 
TO AROUND 20 KT SUN NIGHT.

GULF OF PANAMA...LATEST MODEL GUIDANCE INDICATES 20 KT NORTHERLY 
WINDS IN THE GULF OF PANAMA BEGINNING TONIGHT AS THE PRES 
GRADIENT OVER WESTERN COLOMBIA TIGHTENS.

FOR THE LATEST INFORMATION ON PACIFIC TSUNAMI REPORTS REFER TO 
BULLETINS FROM THE PACIFIC TSUNAMI CENTER USING HEADERS WEPA40 
PHEB OR TSUPAC. 

$$
STRIPLING