000
AXPZ20 KNHC 130914
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI AUG 13 2010

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 
0700 UTC.

...SPECIAL FEATURE...

A 1006 MB LOW IS LOCATED W-SW OF ACAPULCO MEXICO NEAR 16N101W 
AND IS CURRENTLY MOVING NW AT AROUND 10 KT. SCATTERED MODERATE 
TO STRONG CONVECTION LIES WITHIN 90 NM NE QUADRANT OF THE LOW 
WHILE SCATTERED MODERATE CONVECTION IS WITHIN 180 NM NW QUADRANT 
OF THE LOW. THIS LOW IS FORECAST TO MOVE NW INTO THE HIGH 
TERRAIN OF MAINLAND MEXICO OVER THE NEXT TWO DAYS...POSSIBLY AS 
A TROPICAL CYCLONE.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ANALYZED ALONG A LINE FROM 
11N86W TO 16N99W TO 09N118W TO 11N135W TO 10N140W.  SCATTERED 
MODERATE CONVECTION IS WITHIN 45 NM N AND 120 NM S OF THE ITCZ 
AXIS BETWEEN 86W AND 88W AS WELL AS 45 NM EITHER SIDE OF THE 
ITCZ AXIS BETWEEN 92W AND 94W.

...DISCUSSION...

AN UPPER LEVEL ANTICYCLONE LIES NEAR 28N115W AND EXTENDS A RIDGE 
EASTWARD ACROSS EXTREME NW MEXICO AS WELL AS SOUTHWESTWARD TO 
NEAR 20N138W. AN UPPER TROUGH LIES N OF THIS RIDGE AXIS FROM 
22N138W TO 30N135W AND THEN N OF AREA. DRY AIR IN SUBSIDENCE CAN 
BE FOUND IN MUCH OF THE REGION NW OF A LINE FROM 30N122W TO 
24N132W AND TO THE ITCZ ALONG 132W. ON THE SE SIDE OF THE RIDGE 
LIES ANOTHER UPPER TROUGH. THIS TROUGH EXTENDS FROM AN UPPER LOW 
OVER NORTHERN MEXICO NEAR 26N103W SOUTHWESTWARD TO 16N114W. 
ANOTHER ANTICYCLONE ALOFT LIES SE OF THIS TROUGH NEAR 20N97W.

A SURFACE RIDGE LIES FROM A 1026 MB HIGH NW OF THE AREA NEAR 
34N152W THROUGH 30N140W AND 24N130W TO 21N110W. THE PRESSURE 
GRADIENT BETWEEN THIS RIDGE AND TROUGHING IN THE GULF OF 
CALIFORNIA WILL RESULT IN N TO NW WINDS TO 20 KT NEAR THE W 
COAST OF BAJA CALIFORNIA N OF 26N OVER THE NEXT FEW DAYS. 
SOUTHEAST OF THE RIDGE LIES TWO AREA OF LOW PRES. THE WESTERN 
LOW PRES SYSTEM WAS ANALYZED NEAR 16N111W 1007 MB AND HAS NO 
SIGNIFICANT DEEP CONVECTION NEAR IT. THE EASTERN LOW IS 
DESCRIBED IN THE SPECIAL FEATURES SECTION. THE BROAD AREA OF LOW 
PRES ASSOCIATED WITH BOTH OF THESE SYSTEMS IS DRAWING ITCZ 
MOISTURE NORTHEASTWARD FROM CENTRAL WATERS. 20 KT SOUTHWEST 
WINDS FEEDING INTO THE SOUTH SIDE OF THIS BROAD TROUGH ARE 
HELPING KEEP SEAS IN THE 8 TO 10 FT RANGE IN SW SWELL. AS THE 
EASTERN SURFACE LOW MOVES INLAND...THE MID LEVEL ENERGY 
ASSOCIATED WITH IT IS EXPECTED TO MERGE WITH THE SYSTEM TO THE 
WEST. THE WESTERN LOW IS FORECAST TO REMAIN STATIONARY FRI AND 
SHIFT NORTHWARD SAT AS THIS ENERGY IS INCORPORATED INTO ITS 
NORTHERN EDGE.

UPPER LEVEL DIFFLUENCE OFF THE COAST OF COSTA RICA IS ENHANCING 
THE SCATTERED MODERATE CONVECTION FOUND N OF 05N TO THE COAST 
BETWEEN 82W AND 86W. THIS CONVECTION IS ALSO ASSOCIATED WITH 
SHORTWAVE ENERGY THAT HAS BROKEN OFF FROM THE TROPICAL WAVE IN 
THE SW CARIBBEAN. THIS SYSTEM IS EXPECTED TO FORCE A SURFACE 
TROUGH IN THE EASTERN PACIFIC N OF 04N THAT WILL MOVE W FROM 
COASTAL COSTA RICA THROUGH THE GULF OF FONSECA. A FEW OF THE 
MODELS FAVOR SOME DEVELOPMENT OF THIS SYSTEM OVER THE NEXT DAY 
OR TWO...BUT INCREASING NW FLOW OVER THE NORTHERN PORTION OF THE 
TROUGH LATER IN THE WEEKEND IS EXPECTED TO THEN INHIBIT ANY 
FURTHER DEVELOPMENT.

$$
SCHAUER