000
AXPZ20 KNHC 300321
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI JUL 30 2010

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0115 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE IS ANALYZED ALONG A LINE FROM 
10N86W TO 09N93W TO 13N113W TO 09N126W TO 10N140W. SCATTERED 
MODERATE CONVECTION IS WITHIN 210 NM S OF THE AXIS BETWEEN 100W 
AND 114W.

...DISCUSSION...

AN UPPER LEVEL TROUGH AXIS PASSES THROUGH 30N137W TO 25N140W. A 
30-50 KT UPPER LEVEL JET STREAM IS WITHIN 750 NM TO THE EAST OF 
THE TROUGH AXIS FROM 27N TO 30N. ELSEWHERE...UPPER LEVEL 
ANTICYCLONIC FLOW COVERS MUCH OF THE AREA TO THE NORTH OF 10N W 
OF 115W WITH A RIDGE AXIS EXTENDING FROM AN ANTICYCLONE OVER NE 
ARIZONA THROUGH THE NORTHERN BAJA PENINSULA TO 20N135W. A WEAK 
UPPER TROUGH LIES FROM 27N117W TO 20N112W. THIS PATTERN IS 
EXPECTED TO BECOME MORE AMPLIFIED AND RETROGRADE SLIGHTLY 
WESTWARD DURING THE NEXT COUPLE OF DAYS. DRY AIR IN SUBSIDENCE 
CAN BE FOUND IN MOST OF THE REGION N OF A LINE FROM 15N140W TO 
15N125W TO 30N116W...BUT SOME MOISTURE ALOFT IS BEGINNING TO 
CROSS THIS LINE FROM THE SE AND MOVE INTO THE ENTRANCE REGION OF 
THE AFOREMENTIONED UPPER JET. BROAD SURFACE ANTICYCLONIC FLOW 
COVERS THE AREA TO THE NORTH OF 15N AND WEST OF 115W. A 
SURFACE TROUGH IS ANALYZED FROM 17N117W TO 10N119W. SOUTHERLY 
SWELLS TO 9 FEET ARE LOCATED SOUTH OF 10N W OF 100W AND INTO 
CENTRAL WATERS S OF 19N BETWEEN 103W AND 110W WHERE SE WINDS TO 
20 KT CAN BE FOUND N OF 16N.

MODERATE EASTERLY TO NORTHEASTERLY WINDS ALOFT COVER THE EASTERN 
PORTION OF THE DISCUSSION AREA. AT THE SURFACE...A LOW IS 
EMBEDDED IN THE ITCZ NEAR 09N93W. SCATTERED MODERATE CONVECTION 
IS WITHIN 150 NM W SEMICIRCLE OF THE LOW. SOME OF THE COMPUTER 
MODEL GUIDANCE SUGGESTS THAT SHORTWAVE ENERGY OVER THE ISTHMUS 
OF TEHUANTEPEC WILL SEEP SOUTHWARD THROUGH THE GULF OF 
TEHUANTEPEC INTO THE WESTERN SIDE OF THIS PACIFIC LOW. THE 
PASSAGE OF THE SHORTWAVE ENERGY HAS BROUGHT N TO NE WINDS TO 
20 KT IN THE GULF OF TEHUANTEPEC AND THEY ARE EXPECTED TO 
INCREASE TO 25 KT DOWNWIND OF THE GULF OF TEHUANTEPEC BY FRI 
MORNING. WINDS ARE EXPECTED TO DIMINISH BELOW 20 KT HERE BY SAT 
EVENING.

$$
SCHAUER