000
AXPZ20 KNHC 211001
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED MAR 21 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0915 UTC.

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

ITCZ NOT PRESENT AT THIS TIME. NO SIGNIFICANT CONVECTION.

...DISCUSSION...
VERY BROAD DEEP LAYERED RIDGING DOMINATING MOST OF THE AREA THE 
PAST FEW DAYS HAS BEGUN TO SHIFT E IN RESPONSE TO LONG WAVE 
UPPER TROUGH MOVING INTO NE PACIFIC. UPPER ANTICYCLONE HAS 
SHIFTED E TO NEAR 28N125W...WITH SHORTWAVE MIDDLE TO UPPER LEVEL 
TROUGH DIRECTLY TO THE W...AND MOVING SLOWLY E ACROSS 140W ATTM. 
TO THE E...A SLOW MOVING DEEP LAYERED CYCLONE ACROSS THE CENTRAL 
U.S. WAS ALONG ABOUT 100W...WITH CENTER OVER NW TEXAS...AND 
MIDDLE TO UPPER LEVEL TROUGH EXTENDING SW ACROSS MEXICO TO 
21N118W. UPPER LEVEL WESTERLIES PREVAIL TO THE S OF THESE 
FEATURES...S OF 13N...FLOWING E ACROSS CENTRAL AMERICA.   

THE BROAD RIDGE HAS SUPPORTED A VERY BROAD SURFACE RIDGE THE 
PAST FEW DAYS THEN HAS ALSO BEGUN TO WEAKEN...NOW ANCHORED ON A 
10 25 MB HIGH NEAR 31N130W...EXTENDING SE TO 15N103W. THE PRES 
GRADIENT BETWEEN THE HIGH AND ELONGATED LOW PRES ACROSS MEXICO 
CONTINUES TO YIELD FRESH NWLY WINDS ALONG THE W COAST OF BAJA 
CALIFORNIA. INSIDE THE GULF OF CALIFORNIA...STRONG NWLY WINDS OF 
20 TO 25 KT WITH GUSTS TO 30 KT HAVE SPREAD THROUGH THE FULL 
LENGTH OF THE BASIN...WITH SEAS HAVING BUILT TO AROUND 8 FT 
BETWEEN 27N AND 25N. S OF THE RIDGE...AN ELONGATED ZONE OF FRESH 
NELY TRADEWINDS PREVAILS FROM 07N TO 16N W OF 125W AND FROM 09N 
TO 11N BETWEEN 113W AND 125W. NE WIND WAVES ARE COMBINING WITH 
MODERATE TO LARGE NW SWELL ACROSS THE REGION TO PRODUCE SEAS OF 
8 TO 11 FT. ALTHOUGH NO TRUE ITCZ CURRENTLY EXISTS ACROSS THE 
AREA...AN ELONGATED CONVERGENCE ZONE ALONG THE S EDGE OF THESE 
NE TRADES IS PRODUCING A 180 NM WIDE ZONE OF LOW AND MIDDLE 
CLOUDS WITH SCATTERED WEAK CONVECTION...AND ISOLATED TSTMS. A 
COLD FRONT SUPPORTED BY THE APPROACHING LONG WAVE TROUGH WILL 
MOVE INTO THE NW CORNER OF THE FORECAST AREA THIS EVENING AS AID 
IN THE SURFACE HIGH SHIFTING SE AND COLLAPSING. THIS WILL 
SIGNIFICANTLY WEAKEN THE PRESSURE GRADIENT TO BOTH THE E AND S 
OF THE RIDGE...LEADING TO WEAKENING WINDS ACROSS MUCH OF THE 
AREA.

TO THE E AND SE OF THE RIDGE...TWO LOW LEVEL TROUGHS EXIST AND 
ARE FORCING CONVECTION. THE FIRST LOW TO MIDDLE LEVEL TROUGH WAS 
LOCATED JUST E OF THE BAY OF CAMPECHE EXTENDING SW TO NEAR 
13N97W. SCATTERED WEAK CONVECTION EMBEDDED WITHIN BROKEN TO 
OVERCAST LOW AND MIDDLE CLOUDS WAS FOUND WITHIN 150 NM SE OF THE 
TROUGH...WITH OCCASIONAL ISOLATED TSTORMS. A MORE PRONOUNCED AND 
LONG LIVED TROUGH IS CURRENTLY  FROM 09N86W TO 07N87.5W TO 
03N94W...WHERE SCATTERED MODERATE TO STRONG CONVECTION CONTINUES 
WITHIN 210 NM SE OF THE TROUGH. THIS AREA OF CONVECTION IS 
EXPECTED TO REMAIN VERY ACTIVE THROUGH THIS AFTERNOON BEFORE 
WEAKENING AND SHIFTING SW. OTHERWISE...LIGHT TO MODERATE WINDS 
WITH SEAS 6 FT AND LESS PREVAIL E OF 105W. VERY LONG PERIOD SRN 
HEMI SWELL WILL MOVE INTO THIS AREA THU EVENING AND RAISE WAVE 
HEIGHTS ABOVE 8 FT ALONG THE EQUATOR...AND BRINGING LARGE AND 
POWERFUL SURF TO THE CENTRAL AMERICAN COASTS THU NIGHT THROUGH 
FRI. 

$$
STRIPLING