000
AXPZ20 KNHC 180238
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI MAR 18 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 
0300 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE AXIS IS CENTERED ALONG 03N78W TO 
04N100W TO 07N115W TO 04N130W TO 04N140W. SCATTERED MODERATE TO 
ISOLATED STRONG CONVECTION IS FROM 05N TO 09N BETWEEN 120W AND 
125W. SCATTERED MODERATE CONVECTION IS WITHIN 90 NM EITHER SIDE 
OF AXIS W OF 134W.

...DISCUSSION...

A RATHER BROAD UPPER LEVEL TROUGH IS OVER THE N WATERS EXTENDING 
FROM 30N129W TO NEAR 16N140W. A JET STREAM BRANCH WITH CORE 
WINDS OF 70-90 KT ROUNDS THE BASE OF THE TROUGH EXTENDING NE TO 
ACROSS SOUTHERN CALIFORNIA. THESE WINDS ARE TRANSPORTING 
ABUNDANT MID TO UPPER LEVEL MOISTURE NORTHEASTWARD TO WELL 
INLAND THE INTERMOUNTAIN REGION OF THE U.S.

TO THE SE OF THE UPPER LEVEL TROUGH...MODERATE TO STRONG 
SUBSIDENCE COVERS THE AREA FROM 15N TO 23N W OF 120W. THIS IS 
MAINTAINING RATHER DRY AND STABLE CONDITIONS AT THE SURFACE 
WHERE BROKEN STRATOCUMULUS CLOUDS MOVING SW TO W ARE SEEN. 

MODERATE TO STRONG SUBSIDENCE ALSO DOMINATES THE FAR EASTERN 
SECTION OF THE DISCUSSION AREA MAINLY S OF 20N AND E OF 105W. 
ONLY A FEW SHOWERS ARE NOTED DOWNSTREAM OF THE GULF OF 
TEHUANTEPEC AND NEAR THE COAST OF COLOMBIA. 

AT THE SURFACE...A TROUGH IS WITHIN THE ITCZ AND EXTENDS ALONG 
120W FROM 05N TO 10N. THE TROUGH IS ENHANCING SOME CONVECTION N 
OF THE ITCZ AS DESCRIBED IN THE ITCZ SECTION. STRONG HIGH PRES 
BUILDING SE IS PRESENT TO THE N OF 16N AND W OF 110W. THE PRES 
GRADIENT TO THE S OF THE RIDGE IS SUPPORTING NE-E TRADES OF 
20-25 KT OVER AN AREA FROM 05N TO 27N W OF 125W. THE MOST RECENT 
ASCAT PASS CORROBORATED THESE WIND SPEEDS. THE RIDGE WILL SHIFT 
SOUTHWARD OVER N WATERS DURING THE NEXT FEW DAYS ALLOWING FOR 
THE AREA OF TRADES TO DIMINISH. FRESH TO STRONG NW WINDS ARE 
PRESENT E OF THE RIDGE IN THE FAR NE WATERS ALONG THE COAST OF 
BAJA CALIFORNIA PENINSULA. THESE WINDS ARE FORECAST TO PERSIST 
OVER THE NEXT FEW DAYS. A COLD FRONT CURRENTLY LOCATED WELL TO 
THE N OF THE FORECAST AREA...ASSOCIATED WITH A VIGOROUS UPPER 
LEVEL LOW...IS FORECAST TO APPROACH THE FAR N WATERS BY LATE 
SAT. EXPECT WLY WINDS TO INCREASE TO 20 KT AHEAD OF THE FRONT 
SAT NIGHT. NEW COMPUTER MODEL RUNS INDICATE THE POSSIBILITY OF 
STRONGER WINDS AHEAD OF THE FRONT THAT COULD REACH NEAR GALE 
FORCE BY SUN MORNING.   

REGIONAL WATERS...W OF 110W...ARE DOMINATED BY LARGE NW SWELLS 
WHICH ARE FORECAST TO SUBSIDE THROUGH LATE FRI. HOWEVER...A NEW 
SET OF LARGE SWELLS IS FORECAST TO SPREAD SE INTO THE NORTHERN 
AND CENTRAL PORTIONS IN ASSOCIATION WITH THE AFOREMENTIONED 
COLD FRONT.

GAP WINDS...
GULF OF TEHUANTEPEC...N WINDS WILL CONTINUE TO FUNNEL THROUGH 
THE ISTHMUS OF TEHUANTEPEC THROUGH THE FORECAST PERIOD. WINDS 
WILL PULSE TO 25 KT IN THE MORNING HOURS WHEN DRAINAGE FLOW 
THROUGH THE ISTHMUS WILL BE AT ITS DIURNAL MAXIMUM. 

GULF OF PAPAGAYO...NE TO E WINDS OF 20-25 KT WILL CONTINUE TO 
BLOW DOWNWIND OF THE GULF WITH LITTLE CHANGE OVER THE NEXT 48 
HOURS. 

GULF OF PANAMA...A STRONG PRES GRADIENT BETWEEN THE COLOMBIAN 
LOW AND HIGH PRES OVER CENTRAL AMERICA IS RESULTING IN N WINDS 
OF 20-25 KT ACROSS THE GULF OF PANAMA. 

$$
GR