000
AXPZ20 KNHC 120354
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC MON MAR 12 2012

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 
0330 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

MONSOON TROUGH NOT PRESENT ACROSS E PACIFIC. ITCZ AXIS EXTENDS 
FROM 05N89W TO THE EQUATOR ALONG 107W AND THEN CONTINUES W-SW IN 
THE SOUTHERN HEMISPHERE. SCATTERED MODERATE TO STRONG CONVECTION
IS WITHIN 60 NM N OF THE AXIS BETWEEN 95W-101W.

...DISCUSSION...

A LARGE MIDDLE TO UPPER LEVEL CUT-OFF LOW OVER THE SW U.S. 
YESTERDAY HAS LIFTED OUT TO THE NE OVER CENTRAL KANSAS THIS 
EVENING WITH TRAILING SHEARED MID LEVEL TROUGH EXTENDING SW 
ACROSS NRN MEXICO AND THE S TIP OF THE BAJA PENINSULA TO NEAR 
22N115W. ANOTHER SHORTWAVE TROUGH EXTENDING FROM SRN CALIFORNIA 
TO 25N130W WAS SWEEPING RAPIDLY E. WATER VAPOR IMAGERY SHOWED 
MODERATE TO STRONG SUBSIDENCE NW OF THE SECONDARY TROUGH AXIS 
COVERING THE AREA N OF 19N AND SE OF A LINE FROM NORTHERN BAJA 
CALIFORNIA TO 19N134W. TO THE E OF THIS WAS A SHORTWAVE RIDGE 
ACROSS CENTRAL AMERICA EXTENDING N-NE INTO THE SE U.S. 
OTHERWISE...GENERALLY ZONAL FLOW DOMINATED ALL BUT NW PORTIONS 
OF THE DISCUSSION AREA. A BROAD AND ENERGETIC UPPER TROUGH 
DOMINATES THE NE PACIFIC N OF 29N WITH SEVERAL SHORTWAVES MOVING 
THROUGH THE TROUGH. PRESENTLY...A COUPLE OF SHORTWAVE TROUGHS 
WERE MOVING THROUGH SE THE BASE OF THE BROADER TROUGH WITH A 
MIDDLE TO UPPER LEVEL TROUGH EXTENDING WWD IN A TUTT LIKE 
FASHION TO BEYOND 20N150W. THIS FEATURE SUPPORTS A WEAKENING 
COLD FRONTAL BOUNDARY THAT WAS JUST ENTERING THE FAR NW CORNER 
OF THE DISCUSSION AREA THIS EVENING. THIS FRONT WILL DRIFT SE 
AND INTO FAR NW PORTIONS OF THE AREA THIS EVENING AND BECOME 
NEARLY STATIONARY ON MON BEFORE DISSIPATING TUE. A MORE 
SIGNIFICANT FRONT IS FORECAST TO MOVE INTO THE NW PORTION OF THE 
AREA LATE TUE WITH SW WINDS INCREASING TO 20 KT N OF 29N AHEAD 
OF THE FRONT LATE TUE. 

THE BROAD UPPER TROUGH OVER THE NE PACIFIC IS FORECAST TO SHIFT 
EASTWARD THROUGH MON AS A MORE PRONOUNCED UPPER TROUGH MOVES 
INTO THE NW PORTION OF THE DISCUSSION AREA LATE MON INTO TUE.

ELSEWHERE AT THE SURFACE...THE EPAC HIGH PRES RIDGE WAS CENTERED 
ON A 1036 MB HIGH OVER THE NORTH-CENTRAL PACIFIC WELL NW OF THE 
HAWAIIAN ISLANDS NEAR 36N168W. THE RIDGE BRIDGED ACROSS THE 
COLD FRONT AND SE TO NEAR 19N107W. THE PRES GRADIENT TO THE S OF 
THE RIDGE WAS INDUCING NE TRADES OF 20-25 KT GENERALLY N OF 05N 
TO A LINE FROM 21N140W TO 12N123W WITH SEAS IN THE 8-12 FT 
RANGE. THIS AREA OF TRADES IS FORECAST TO DIMINISH IN THE 
SOUTHERN LATITUDES BY THE NEXT 24 HRS...THEN DIMINISH 
CONSIDERABLY BOTH IN AREAL COVERAGE AND IN WIND SPEEDS BY 48 HRS 
AS THE RIDGE BREAKS DOWN TO A 1018 TO 1020 MB HIGH CENTER IN THE 
NE PART OF THE AREA. 

THE MAIN IMPACT OF THESE FRONTS MOVING INTO THE NORTHERN WATERS 
THROUGH THE NEXT 48 HRS WILL BE THE ASSOCIATED PULSES OF LONG 
PERIOD NW SWELLS SWEEPING SE ACROSS THE AREA. NWLY SWELL 
CURRENTLY ACROSS NW PORTIONS OF THE AREA WILL SLOWLY DECAY 
THROUGH TONIGHT ALLOWING FOR SEAS TO LOWER TO 9 FT FOR THE MOST 
PART. ANOTHER PULSE OF LONG PERIOD SWELLS WILL ARRIVE WITH THE 
STRONGER COLD FRONT TUE MORNING AND PRODUCE SEAS OF 9 TO 11 FT  
N OF 27N AND W OF 125W BY TUE EVENING.

GAP WINDS... 
THE GULF OF TEHUANTEPEC...THE SMALL AND NARROW PLUME OF 
NORTHERLY WINDS HAVE DROPPED BELOW 20 KT THIS EVENING. WINDS 
WILL INCREASE TO 20-25 KT AGAIN EARLY MON AND CONTINUE THROUGH 
48 HOURS. 

THE GULF OF PAPAGAYO...FRESH TRADES ACROSS THE CARIBBEAN 
CONTINUE TO FUEL GAP WIND FLOW ACROSS CENTRAL AMERICA THEN 
THROUGH THE GULFS OF PAPAGAYO AND FONSECA AND WELL SW TO NEAR 
92W THIS AFTERNOON...WITH DOWNWIND SEAS PRESENTLY AT 8 TO 10 FT. 
HIGH PRES IS EXPECTED TO BUILD S AND SW ACROSS THE BAHAMAS AND W 
CARIBBEAN IN THE NEXT 24 HOURS AND WILL REINFORCE THIS FLOW 
THROUGH THROUGH THE GULF...WITH AREAS TO 30 KT EXPECTED BY MON. 
THIS AREA OF 20 KT WINDS AND HIGHER IS EXPECTED TO SPREAD WILL 
DOWNWIND TO 110W BY TUE MORNING DUE TO THE INCREASED PRES 
GRADIENT ACROSS THE W CARIBBEAN. 

THE GULF OF PANAMA...TRADES IN THE SOUTHWESTERN CARIBBEAN SEA 
WILL CONTINUE TO SUPPORT PULSES OF FRESH NORTHERLY FLOW ACROSS 
THE ISTHMUS OF PANAMA AND ACROSS THE GULF OF PANAMA. SEAS OF 6 
TO 8 FT ARE EXPECTED TO CONTINUE S AND SW OF THE GULF. WINDS 
WILL BEGIN TO DECREASE TO AROUND 20 KT BY 48 HOURS. 

$$
COBB