000
AXPZ20 KNHC 031603
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE APR 03 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1530 UTC.

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

A SURFACE TROUGH EXTENDS FROM 09N84W TO 05N90W TO 04N98W.
SCATTERED STRONG CONVECTIVE PRECIPITATION IS FROM 01N TO 03N 
BETWEEN 96W AND 100W. SCATTERED MODERATE TO ISOLATED STRONG 
CONVECTIVE PRECIPITATION IS FROM 06N TO 09N BETWEEN 81W AND 
85W...AND FROM 01N TO 03N BETWEEN 101W AND 103W.

THE ITCZ IS ALONG 07N110W 08N113W 05N130W 05N140W. SCATTERED 
MODERATE TO ISOLATED STRONG CONVECTIVE PRECIPITATION IS FROM
06N TO 10N BETWEEN 113W AND 130W.

...DISCUSSION...

THE AMPLIFIED NORTHERN STREAM PATTERN ALOFT CURRENTLY IN PLACE 
WILL GRADUALLY BREAK DOWN OVER THE NEXT TWO DAYS. THE UPPER LOW 
OVER THE FOUR CORNERS STATES WILL MOVE EASTWARD QUITE SLOWLY 
TODAY...ALLOWING THE RIDGING TO ITS W TO ERODE AS THE NEXT 
TROUGH APPROACHES. THIS SECOND TROUGH IS CONSIDERABLY LESS 
AMPLIFIED THAN THE TROUGHING OVER MEXICO ASSOCIATED WITH THE 
AFOREMENTIONED UPPER LOW. THESE CHANGES TO THE PATTERN WILL 
ALLOW FOR THE FLOW TO BECOME RELATIVELY ZONAL ALOFT N OF 29N BY 
THIS EVENING. 

THE SUBTROPICAL HIGH PRESSURE CENTER IS NEAR 28N133W. IT HAS 
WEAKENED DURING THE PAST 24 HOURS TO 1022 MB. THE SURFACE 
PRESSURE GRADIENT THAT EXISTS BETWEEN THE HIGH AND A BROAD 
SURFACE TROUGH THAT IS IN MEXICO...HAS BEEN COMPARATIVELY STRONG 
ENOUGH IN ORDER TO SUPPORT A SMALL AREA OF STRONG NORTHERLY 
WINDS AND SEAS TO 16 FEET. THE SEA HEIGHTS ARE FORECAST TO 
DECREASE WITH TIME TO 9 FEET...BY THE 48 HOUR TIME LIMIT.
THE SURFACE TROUGH IN MEXICO IS ASSOCIATED WITH THE UPPER 
LEVEL CYCLONIC CIRCULATION CENTER. THE WINDS IN THIS AREA WILL 
DIMINISH LATER TODAY AS THE SUBTROPICAL HIGH PRESSURE CENTER
CONTINUES TO BE WEAKENED BY THE NEXT DEEP LAYER TROUGH THAT
IS APPROACHING FROM THE NORTHWEST. THE COLD FRONT THAT IS
ASSOCIATED WITH THIS WESTERN TROUGH ALOFT WILL MOVE SLOWLY
THROUGH THE NORTHWESTERN WATERS BEGINNING LATER THIS 
AFTERNOON. THE FRONT WILL ENTER THE FORECAST AREA WITH 
CONSIDERABLY LESS FANFARE THAN ITS PREDECESSOR...WITH FRESH 
NORTHEASTERLY WINDS BEHIND IT AND SEAS TO 9 FT. NORTHWESTERLY
SWELL BEHIND THE PREVIOUS COLD FRONT CONTINUES TO MOVE SOUTHWARD 
THROUGH THE FORECAST AREA. 

AN UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR 17N126W.
CONVECTIVE PRECIPITATION WAS OCCURRING TO THE EAST AND SOUTHEAST 
OF THIS CENTER. NO SIGNIFICANT DEEP CONVECTIVE PRECIPITATION IS  
NEAR THE CYCLONIC CENTER AT THIS MOMENT. HIGH LEVEL CLOUDS ARE 
FROM 10N TO 20N TO THE EAST OF 130W. THEY ARE MOVING 
NORTHEASTERLY AND EASTERLY. 

A SURFACE TROUGH EXTENDS FROM COASTAL COSTA RICA NEAR 09N84W TO 
05N90W TO 04N98W. SCATTERED STRONG CONVECTIVE PRECIPITATION IS 
FROM 01N TO 03N BETWEEN 96W AND 100W. SCATTERED MODERATE TO 
ISOLATED STRONG CONVECTIVE PRECIPITATION IS FROM 06N TO 09N 
BETWEEN 81W AND 85W...AND FROM 01N TO 03N BETWEEN 101W AND 103W.
THE 40-50 KT WEST-SOUTHWESTERLY VERTICAL SHEAR OVER THE TROUGH 
THAT IS INHIBITING CONVECTIVE PRECIPITATION SHOULD RELAX A BIT
BY WEDNESDAY NIGHT.

THE GULF OF CALIFORNIA...THE SURFACE PRESSURE GRADIENT BETWEEN
THE WEAKENING SUBTROPICAL HIGH PRESSURE CENTER AND THE TROUGH 
THAT IS IN CENTRAL MEXICO CONTINUES TO SUPPORT FRESH 
NORTHWESTERLY TO NORTHERLY WINDS FROM 24N AND 29N. SOME OF THESE 
WINDS WERE CAPTURED BY THE 03/0402 UTC ASCAT PASS. THE WINDS ARE 
FORECAST TO DIMINISH DURING THE NEXT 6 HOURS OR SO.

$$
MT