000
AXPZ20 KNHC 130947
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT JUN 13 2009

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 
09155 UTC.

...ITCZ...

AXIS IS CENTERED ALONG 10N84W TO 8N95W TO 9N105W TO 11N118W TO 
10N126W TO 8N140W. SCATTERED STRONG CONVECTION IS WITHIN 60 NM S
OF THE AXIS BETWEEN 135W-139W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS OCCURRING WITHIN 180 NM S OF THE AXIS BETWEEN 
86W-89W...91W-94W AND 101W-107W.
  
...DISCUSSION...

A 1012 MB SURFACE LOW IS ANALYZED NEAR 17N117W MOVING ESE 8 KT. 
A SURFACE TROUGH EXTENDS FROM THE LOW SW TO 12N124W. THIS FEATURE
IS IN VERY HOSTILE ENVIRONMENT CONSISTING OF MID/UPPER-LEVEL DRY 
AIR...RELATIVELY COOL SEA SURFACE TEMPERATURES...AND MODERATE TO
STRONG SWLY SHEAR E OF AN UPPER TROUGH AXIS THAT STRETCHES FROM 
32N120W TO 21N123W TO NEAR 14N126W. WHILE THESE CONDITIONS ARE 
INHIBITING ORGANIZED DEEP CONVECTION NEAR THE LOW...COOLER 
MID-LEVEL TEMPERATURES NEAR THE UPPER TROUGH CONTINUES TO
SUSTAIN A CLUSTER OF SCATTERED MODERATE PULSE CONVECTION NW OF
THE CENTER WITHIN 30 NM OF 19N116W. THE PRES GRADIENT BETWEEN 
THE LOW AND HIGH PRES TO ITS NW IS ENOUGH TO PRODUCE 20 KT
WINDS WITHIN 120 NM NW SEMICIRCLE OF THE LOW. LATEST SATELLITE 
IMAGERY SHOWS THE CENTER OF THE LOW ALREADY EXPOSED INDICATING A 
WEAKENING SYSTEM UNDERGOING VERTICAL SHEAR. SURFACE PRESSURES IN 
THE SURROUNDING ENVIRONMENT OF THE LOW ARE EXHIBITING A RISING 
TENDENCY. WITH THIS IN MIND...THE LOW IS TRANSITIONING INTO A 
TROUGH WITH DISSIPATING EXPECTED IN 18 HOURS AT WHICH TIME IT 
WIND FIELD WILL DIMINISH TO LESS THAN 20 KT.

IN THE WAKE OF THE UPPER TROUGH MENTIONED ABOVE...THE UPPER FLOW 
IS NW TO N DUE ALSO TO AN UPPER LEVEL ANTICYCLONE THAT IS 
WELL W OF THE AREA. TO THE SE OF THE TROUGH...AN UPPER LEVEL 
ANTICYCLONE IS NOTED OVER CENTRAL MEXICO WITH AN ASSOCIATED 
RIDGE EXTENDING SW ACROSS THE EASTERN PORTION OF THE PACIFIC TO 
NEAR 7N115W. A MID/UPPER LEVEL RIDGE ENTERS THE AREA AT 9N140W 
AND EXTENDS E TO 9N133W TO 9N127W. THIS RIDGE EXTENDS W TO AN
ANTICYCLONE W OF THE AREA NEAR 9N145W. AT THE SURFACE...A RIDGE 
ENTERS THE DISCUSSION AREA THROUGH 28N140W AND CONTINUES SEWD TO
JUST NW OF THE LOW NEAR 17N117W. THE PRES GRADIENT AT THE 
SOUTHERN PERIPHERY OF THIS RIDGE IS ALLOWING FOR NE TRADE WINDS 
TO 20 KT TO BE CONFINED FROM 10N-19N W OF 132W AS CONFIRMED BY 
A QUIKSCAT PASS VALID SHORTLY AFTER 0300 UTC. THESE WINDS ARE 
FORECAST TO REMAIN IN PLACE DURING THE 48 HOURS AS THE AREA 
SHIFTS SOME TO THE W. 

MID/UPPER LEVEL RIDGING W OF THE AREA N OF 23N WILL SLOWLY 
TRANSLATE EASTWARD OVER THE NEXT COUPLE OF DAYS RESULTING IN THE 
SURFACE HIGH DRIFTING EASTWARD ALONG WITH THE ATTENDANT SURFACE 
RIDGE. THE UPPER TROUGH IS FORECAST TO DAMPEN SOME LATE SUN
OVER THE FAR NE PORTION OF AREA AFTER SENDING A SHORTWAVE TROUGH
OVER THE SW U.S. AND NORTHERN MEXICO. A STRENGTHENING SURFACE 
TROUGH OVER MEXICO IS STEEPENING THE PRES GRADIENT ALONG THE 
COAST OF BAJA CALIFORNIA AND EASTWARD ACROSS THE GULF OF 
CALIFORNIA AND MEXICAN COAST S OF ABOUT 26N WHERE NW WINDS OF 
LESS THAN 20 KT ARE PRESENTLY NOTED IN THE LATEST QUIKSCAT AND 
ASCAT PASSES FROM EARLY THIS MORNING. THESE WINDS ARE FORECAST TO
INCREASE TO 20 KT IN THE NEXT 12-18 HOURS. WITH THE SURFACE 
RIDGE BUILDING FURTHER E...THESE WINDS CONTINUE INCREASING IN 
AREAL COVERAGE AND INTENSITY...WITH NW WINDS OF 20-25 KT EXPECTED
IN 24 HOURS FROM FROM 21N TO 27N E OF 114W INCLUDING THE GULF OF 
CALIFORNIA AND DIMINISHING TO 20 KT IN 48 HOURS.

WITH REGARDS TO SEA STATE...S TO SW SWELLS ASSOCIATED WITH WAVE 
HEIGHTS OF 8-10 FT WILL CONTINUE TO OVERSPREAD THROUGHOUT THE 
SOUTHERN WATERS OF THE DISCUSSION AREA DURING THE NEXT 24-36 
HOURS. LATEST WAVE MODEL GUIDANCE IS FOR THE RESULTING WAVES TO 
IMPACT THE COAST OF CENTRAL AMERICA AND ALSO THAT OF SE MEXICO 
THIS WEEKEND RESULTING IN LARGE AND DANGEROUS BREAKING SURF 
CONDITIONS ALONG THOSE COASTS. THE MODEL INDICATES WAVE HEIGHTS 
OF UP TO 8 FT BY SUN WITH WAVE PERIODS OF 13-14 SECONDS.
 
$$
AGUIRRE