000
AXPZ20 KNHC 251605
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON APR 25 2011

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY 
THROUGH 1545 UTC.

...ITCZ...

AXIS IS CENTERED ALONG 6N78W 4N93W 8N105W 6N120W 4N131W 3N140W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION EXISTS FROM 6N-12N
BETWEEN 101W-106W...WITHIN 150 NM N OF THE AXIS BETWEEN 117W-120W
AND 60 NM S OF THE AXIS BETWEEN 113W-115W. SCATTERED MODERATE 
CONVECTION IS WITHIN 120 NM S OF THE AXIS W OF 137W.

...DISCUSSION...

W OF 120W...

N OF 15N
ANTICYCLONIC COVERS THIS AREA DUE TO AN ANTICYCLONE MOVING 
EASTWARD NEAR 29N138.5W. SATELLITE WATER VAPOR IMAGERY IS
SHOWING AMPLE MODERATE SUBSIDENCE ALLOWING FOR DRY AND RATHER 
STABLE ATMOSPHERIC CONDITIONS OVER THIS PORTION OF THE AREA AS 
NOTED
BY THE BROKEN STRATOCUMULUS CLOUD FIELD THAT IS MOVING WESTWARD.
THE ANTICYCLONE IS BLOCKING ANY NRN STREAM DEEP ENERGY FROM 
MOVING
INTO THE DISCUSSION AREA. THE SURFACE HIGH CENTER OF 1026 MB S 
ANALYZED NEAR 31N134W WITH A RIDGE SE TO 25N120W...AND CONTINUES 
TO SE OF 120W. THE ANTICYCLONE IS FORECAST TO GRADUALLY SHIFT 
EASTWARD OVER THE NEXT 24-48 HOURS AS IT LOSES ITS 
IDENTITY...WHILE THE SURFACE HIGH WEAKENS. THE COMBINATION OF 
THE HIGH PRESSURE 
AND LOWER PRESSURE TO THE S IN THE VICINITY OF THE ITCZ IS 
PRODUCING A PRESSURE GRADIENT THAT IS INDUCING AN AREA OF NE 20 
KT TRADE WINDS FROM 8N TO 21N W OF 125W. THESE WINDS WILL SLOWLY 
SHRINK IN AREAL COVERAGE DURING THE NEXT 48 HOURS WITH THE 
EASTWARD SHIFT OF THE HIGH.

S OF 15N
MODERATE TO STRONG W TO NW FLOW IS PRESENT OVER THIS AREA. 
DIFFLUENT FLOW TO THE E OF A LARGE UPPER LEVEL LOW SITUATED 
ABOUT 360 NM SE OF THE HAWAIIAN ISLANDS IS HELPING TO SPREAD 
UPPER LEVEL MOISTURE EASTWARD INTO THE FAR SW PORTION OF THE 
AREA WHERE IT BLENDS IN WITH MOISTURE GENERATED BY ITCZ 
CONVECTION.

E OF 120W...
AN UPPER TROUGH EXTENDS FROM THE CENTRAL U.S. SW TO ACROSS 
NORTHERN
MEXICO...TO SOUTHERN BAJA CALIFORNIA AND TO NEAR 21N120W. 
MODERATE
SUBSIDENCE IS WITHIN 180 NM N OF THE TROUGH. A SMALL ANTICYCLONE 
IS IDENTIFIED TO THE SE OF TROUGH NEAR 8N99W. SW TO W UPPER FLOW
BETWEEN THESE TWO FEATURES IS CONVERGING ALONG THE MEXICAN COAST 
FROM ACAPULCO TO NEAR CABO CORRIENTES. THIS FLOW IS ADVECTING 
SCATTERED TO BROKEN HIGH CLOUDS...MOSTLY DERIVED FROM ITCZ 
CONVECTION
...NE AND E TO ACROSS CENTRAL MEXICO BETWEEN THE PREVIOUSLY 
STATED
LOCATIONS. THE TROUGH IS FORECAST TO SHIFT E OF THE AREA TONIGHT
INTO TUE MORNING AS THE HIGH DESCRIBED ABOVE MOVES EASTWARD. THE 
PRESSURE GRADIENT OVER THE NE WATERS IS ALLOWING FOR NW WINDS OF 
20 KT TO THE N OF 25N AND E OF 120W WITH SEAS TO 8 FT. WITH THE 
HIGH MOVING EASTWARD...THE GRADIENT WILL TIGHTEN SOME MORE AND
ACT TO INCREASE THESE WINDS TO 20-25 KT LATE TONIGHT INTO TUE 
MORNING
...AND CONTINUE THROUGH WED AS THEY EXPAND WESTWARD TO NEAR 
125W. HIGHER SEAS JUST N OF THE AREA WHERE WINDS ARE MUCH 
STRONGER
WILL BEGIN TO FILTER INTO THE WITH RANGES OF 8-12 FT IN LONG 
PERIOD
N SWELLS BY EARLY WED. PERTURBATIONS IN THE TROPICS NOTED AS 
SURFACE TROUGHS ARE LOCATED FROM 9N117W TO NEAR 4N121W...AND FROM
13N104W TO 6N107W. A MID TO UPPER LEVEL TROUGH BETWEEN BOTH OF 
THESE
FEATURES IS PROVIDING UPPER LEVEL DIVERGENCE WHICH IS ACTING 
WITH LOW LEVEL CONVERGENCE W OF THE TROUGHS TO ENHANCE ITCZ 
RELATED CONVECTION AS WELL AS TO CREATE ADDITIONAL CLUSTERS OF 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN ABOUT 150 NM
N OF THE ITCZ BETWEEN 114W AND 121W.

$$
AGUIRRE