000
AXPZ20 KNHC 112211
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI MAR 11 2011

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2115 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS ANALYZED FROM 06N84W TO 
01N90W TO 06N120W TO 04N140W. SCATTERED MODERATE CONVECTION WAS 
NOTED WITHIN 150 NM EITHER SIDE OF AXIS BETWEEN 114W AND 122W. 
SCATTERED MODERATE TO STRONG CONVECTION WAS NOTED WITHIN 120 NM 
N OF AXIS W OF 122W.

...DISCUSSION...

A BROAD AND MAINLY 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 07N110W....WHILE W PORTIONS ARE RESULTANT OF 
UPPER DIVERGENCE INDUCED FROM DEEP ITCZ CONVECTION PREVAILING W 
OF 125W. AN EQUATORIAL UPPER TROUGH WAS NOTED MEANDERING INTO 
BOTH HEMISPHERES...ANCHORED ON AN UPPER CYCLONE JUST S OF THE 
ITCZ NEAR 02N130W. SUBSIDENCE DOMINATES THE AREA N OF 10N E OF 
110W WITH DRY AND STABLE AIR IN PLACE. OTHERWISE AN ENERGETIC 
AND PROGRESSIVE SW-W FLOW PREVAILS ALOFT W-NW OF THE RIDGING AND 
ITCZ...AND CONTINUES TO TRANSPORT PLENTIFUL 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 AND NW 
MEXICO. 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 REACHING SW ACROSS THE FAR NW CORNER OF 
THE AREA THROUGH 30N141W 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...1026 MB HIGH PRES IS POSITIONED NEAR 
29N131W WITH BROAD RIDGING EXTENDING FROM THE HIGH TO NEAR 
14N110W. THIS DEEP LAYERED RIDGING 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. THE RESULT WILL BE NW-N 20 KT WINDS OFF THE 
COAST OF BAJA CALIFORNIA THIS EVENING THROUGH SAT NIGHT.

THE SHIFTING SURFACE HIGH HAS WEAKENED THE PRES GRADIENT N OF 
THE ITCZ...WHICH IS LIMITING FRESH TRADE WINDS CURRENTLY FROM 
FROM 06N TO 13N W OF 119W. THIS AREA OF 20 KT TRADE WINDS IS 
EXPECTED TO SHRINK AND SHIFT TO FROM 07N TO 14N W OF 134W BY 24 
HOURS THEN WILL EXPAND EASTWARD TO 126W BY 48 HOURS BECOMING 
REINVIGORATED AS THE NEXT FRONT APPROACHES FROM THE NW.

GAP WINDS...
GULF OF TEHUANTEPEC...STRONG NORTHERLY WINDS CONTINUE TO SURGE 
THROUGH THE GULF OF TEHUANTEPEC BEHIND A COLD FRONT WHICH HAS 
MOVED E OVER GUATEMALA...BUT HAVE BEGUN TO DIMINISH IN THE PAST 
12 HOURS...AND ARE EXPECTED TO FALL BELOW GALE CRITERIA IN THE 
NEXT 6 HOURS. LATEST WAVE MODEL GUIDANCE SUGGESTS SEAS UP TO 16 
FT WITHING THESE 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 12Z SUN.

GULF OF PAPAGAYO...AS THE ABOVE MENTIONED COLD FRONT CONTINUES 
TO MOVE SOUTHEASTWARD INTO THE WESTERN CARIBBEAN...WINDS WILL 
FUNNEL THROUGH SOUTHERN NICARAGUA AND NORTHERN COSTA RICA 
PRODUCING FRESH NE-E WINDS ACROSS THE GULF OF PAPAGAYO AND 
DOWNWIND TO 89W FRI NIGHT WITH WINDS INCREASING TO 20-25 KT AND 
EXPANDING TO 91W. WINDS WILL CONTINUE TO AFTER 12Z SUN.

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