000
AXPZ20 KNHC 170915
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE AUG 17 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 
0800 UTC.

...TROPICAL WAVE...

A TROPICAL WAVE N OF 10N ALONG 87W HAS BEEN MOVING W AT 8 KT. 
SCATTERED MODERATE CONVECTION LIES W OF THE WAVE OFFSHORE N OF 
11N BETWEEN 88W AND 92W AS WELL AS OVER EASTERN GUATEMALA AND 
SOUTHERN BELIZE.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ANALYZED FROM 
10N115W TO 09N130W TO 09N140W. NO SIGNIFICANT CONVECTION LIES 
NEAR THE ITCZ AT THIS TIME. 10-15 KT SOUTHWESTERLY FLOW 
DOMINATES THE PAC WATERS GENERALLY TO THE S OF 15N BETWEEN 100W 
AND 115W WITH LIGHTER AND MORE VARIABLE WINDS FOUND E OF 100W 
FROM 08N TO 15N ACCORDING TO ASCAT.

...DISCUSSION...

N OF 20N...
AT THE SURFACE...A 1008 MB LOW PRES SYSTEM LIES NEAR 22N111W. 
SATELLITE-MEASURED PRECIPITABLE WATER IMAGERY SHOWS PLENTIFUL 
MOSITURE IN THE LOW AND MID LEVELS BEING PULLED AWAY FROM 
MAINLAND MEXICO AND THE GULF OF CALIFORNIA TOWARD THIS LOW 
RESULTING IN RELATIVELY DRY CONDITIONS OVER THE SIERRA MADRE 
OCCIDENTAL AND THE U.S. SOUTHWEST COMPARED TO THE PAST FEW 
NIGHTS. MID AND UPPER LEVEL MOSITURE IS BEING PULLED FARTHER 
NW TOWARD AN UPPER LOW NEAR 28N125W. THE REGION N OF 12N W OF 
133W IS MARKED BY SUBSIDENCE AND RELATIVELY DRY CONDITIONS WITH 
THE EXCEPTION OF THE MOSITURE DRAWN NORTHWESTWARD AROUND THIS 
UPPER LOW. A 40-50 KT SOUTHWESTERLY UPPER JET LIES OVER FAR NW 
WATERS ON THE LEADING EDGE OF AN UPPER TROUGH. MEANWHILE...AN 
UPPER RIDGE LIES S OF THE UPPER LOW AND EXTENDS FROM AN 
ANTICYCLONE NEAR 20N130W TO ANOTHER NEAR 29N117W THEN ACROSS THE 
NORTHERN GULF OF CALIFORNIA. THIS RIDGE IS EXPECTED TO LIFT N 
AND FORCE THE UPPER LOW NORTHWARD INTO THE JET LATER TODAY WHERE 
IT WILL SHEAR APART. AN UPPER TROUGH LIES ALONG 110W BETWEEN 20N 
AND 30N. 20 KT SOUTHEASTERLY WINDS ALOFT CAN BE FOUND BEHIND 
THIS WESTWARD MOVING TROUGH AND WILL SOON MOVE OVER THE SURFACE 
LOW NEAR 22N111W. THE NORTHWESTWARD DRIFTING SURFACE LOW IS 
APPROACHING THE SURFACE RIDGE AXIS THAT LIES FROM 30N138W TO 
22N117W AND IS EXPECTED TO DISSIPATE TODAY UNDER THESE HOSTILE 
CONDITIONS.

S OF 20N...
STRONG WEST TO NW UPPER LEVEL WINDS CAN BE FOUND IN MUCH OF THE 
REGION S OF 20N E OF 120W AND ARE EXPECTED TO CONTINUE OVER THE 
NEXT FEW DAYS. THIS VERTICAL WIND SHEAR IS GENERALLY INHIBITING 
THE GENERATION OF DEEP CONVECTION. SCATTERED MODERATE CONVECTION 
OFF THE COAST OF GUATEMALA AND EL SALVADOR AHEAD OF THE TROPICAL 
WAVE ALONG 87W IS ENHANCED BY DIFFLUENCE ALOFT ALONG THE WEAK 
UPPER RIDGING AXIS AHEAD OF AN UPPER LEVEL TROUGH THAT EXTENDS 
FROM AN UPPER LOW IN THE CARIBBEAN NEAR 17N83W TO 12N90W. THE 
STRONGEST UPPER DIFFLUENCE IN THIS REGION LIES NEAR THE COAST OF 
COLOMBIA WHERE SCATTERED MODERATE CONVECTION IS WITHIN 75 NM OF 
COAST FROM 03N TO 06N. RELATIVELY STRONG YET MORE VARIABLE WINDS 
ALOFT CAN BE FOUND W OF 120W WHERE CONVECTION IS ALSO SCARCE. A 
WEAK UPPER TROUGH LIES FROM 06N126W TO 20N123W. THIS TROUGH IS 
EXPECTED TO RACE WESTWARD TOWARD THE STATIONARY UPPER LOW NEAR 
03N145W OVER THE NEXT FEW DAYS. 

CROSS EQUATORIAL SWELL WILL REACH 8 FT OVER S CENTRAL WATERS 
THIS MORNING AND SLOWLY MOVE NORTH OF 10N BY LATE WED NIGHT. 
THIS SWELL WILL GRADUALLY MAKE ITS WAY E OF THE GALAPAGOS 
ISLANDS...AND SEAS WILL REACH 8 FT OFF THE COAST OF PANAMA NEAR 
06N BY THE END OF THE FORECAST PERIOD EARLY THU MORNING.

$$
SCHAUER