000
AXPZ20 KNHC 090914
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED APR 09 2008

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0845 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N77W 3N100W 7N113W 4N140W. 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 5N-9N BETWEEN 
78W-85W. SCATTERED MODERATE FROM 2N-5N BETWEEN 93W-100W. 
ISOLATED SHOWERS/TSTMS WITHIN 45 NM OF AXIS BETWEEN 110W-115W 
AND BETWEEN 130W-136W.

...DISCUSSION...

N OF 20N...
AN AMPLIFIED UPPER LEVEL PATTERN PERSISTS OVER NORTH AMERICA AND 
THE NE PACIFIC WATERS...HIGHLIGHTED BY A SHARP LONGWAVE TROUGH 
ALONG 117W ACROSS THE GREAT BASIN AND NORTHERN ROCKIES AND A 
STRONG UPPER HIGH NEAR 36N144W. THE UPPER HIGH WAS PART OF A REX 
BLOCK NE OF HAWAII...BUT THIS PATTERN IS BREAKING DOWN AS THE 
HIGH MOVES E. THE TAIL END OF THE WRN U.S. TROUGH EXTENDS FROM 
NORTHERN BAJA CALIFORNIA TO 27N130W THEN BECOMES A SHEAR AXIS TO 
28N140W WITH A THIN RIBBON OF SUBSIDING AIR IN ITS VICINITY. THE 
SUBTROPICAL JET STREAM EXTENDS FROM 21N140W TO CENTRAL BAJA AND 
NW MEXICO WITH MAXIMUM WINDS ACCELERATING TO 80-85 KT NEAR THE 
MEXICO-ARIZONA BORDER AT THE BASE OF THE TROUGH. BROKEN HIGH 
CLOUDINESS LIES ALONG AND S OF THE SUBTROPICAL JET...AND 
MID/HIGH LEVEL CLOUDS ALONG THE PEAKS OF THE SIERRA MADRE 
OCCIDENTALS WITHIN THE MEXICAN STATES OF DURANGO AND CHIHUAHUA 
IMPLY THAT THE STRONG WESTERLIES ARE IMPINGING ON THE HIGHER 
TERRAIN. BROKEN LOW-LEVEL CLOUDS LIE WITHIN THE SUBTROPICAL 
RIDGE W OF 112W AND ONSHORE FLOW IS BRINGING LOW STRATUS/FOG 
INLAND OVER BAJA CALIFORNIA N OF 27N.

S OF 20N...
DOMINANT UPPER LEVEL FEATURE ACROSS THE AREA IS A FAIRLY STRONG 
HIGH NEAR 14N110W WITH A RIDGE AXIS CONTINUING NE ACROSS 
SOUTHERN MEXICO TO THE BAY OF CAMPECHE. THE HIGH IS BOUNDED BY 
AN UPPER TROUGH WHICH EXTENDS FROM 20N122W TO A WEAK UPPER LOW 
NEAR 5N107W...THEN CONTINUES AS A CYCLONIC SHEAR AXIS TO A 
SECOND UPPER LOW JUST OFF THE NICOYA PENINSULA OF COSTA RICA. 
STRONG SUBSIDENCE LIES E OF THE UPPER HIGH AND N OF THE SHEAR 
AXIS LEADING TO FAIR CONDITIONS OFF THE SW MEXICAN COAST. LAND 
BREEZE CIRCULATIONS OFF THE CENTRAL AMERICAN COAST IS PRODUCING 
SCATTERED MODERATE CONVECTION WITHIN 90 NM OFF THE COASTS OF NW 
COSTA RICA...NICARAGUA...AND EL SALVADOR. W/SW FLOW ALOFT LIES S 
OF THE SHEAR AXIS AND THE DEEPER MOISTURE SUPPLY HAS LED TO THE 
DEVELOPMENT OF SCATTERED SHOWERS/TSTMS NEAR THE ITCZ. FARTHER 
W...ANOTHER UPPER HIGH IS CENTERED NEAR 7N135W TRANSECTED BY A 
SE/NW ORIENTED RIDGE AXIS AND SURROUNDED BY ABUNDANT HIGH 
CLOUDINESS AND ISOLATED ITCZ CONVECTION.

$$
BERG