000
AXPZ20 KNHC 150329
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE SEP 15 2009

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 
0315 UTC.

...SPECIAL FEATURE...

A SURFACE LOW NEAR 16N109W 1008 MB MOVING WNW 8 KT IS PART OF A 
LARGE AREA OF LOW PRES THAT BASICALLY DEFINES A LARGE AND 
PERSISTENT
MONSOONAL CIRCULATION COVERING THE AREA BETWEEN 105W-117W. 
SCATTERED
STRONG CONVECTION IS OCCURRING FROM 15N TO 17N BETWEEN 111W AND 
113W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 30 
NM OF A LINE FROM 17N111W TO 18N110W. SCATTERED MODERATE 
CONVECTION IS WITHIN 45 NM OF 16N106W. THIS SYSTEM REMAINS UNDER 
A DIFFLUENT UPPER PATTERN RESULTING FROM AN UPPER LEVEL 
ANTICYCLONE NEAR 20N108W...AND THE NW PERIPHERY OF BROAD UPPER 
TROUGHING OVER THE SW PORTION OF THE AREA. THIS SYSTEM HAS THE
POTENTIAL TO BECOME A TROPICAL CYCLONE OVER THE NEXT 48 HOURS.

...TROPICAL WAVE...

A TROPICAL WAVE IS ANALYZED ALONG 119W FROM 8N-16N MOVING W AT 
15 KT. ISOLATED TSTMS ARE WITHIN 45 NM OF 12N119W.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N78W 6N86W 10N97W 15N105W 10N120W
8N130W 6N140W. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM S
OF THE AXIS BETWEEN 127W-133W...AND W OF 133W.

...DISCUSSION...

A MID AND UPPER LEVEL TROUGH ENTERS THE FAR NE CORNER OF THE 
AREA THROUGH 32N119W AND EXTENDS SW TO 27N122W. ITS ASSOCIATED
WEAK SURFACE COLD FRONT EXTENDS FROM 32N118W TO 26N122W...BUT 
WILL
DISSIPATE OVER THE NEXT 12 HOURS. AN AMPLIFYING MID/UPPER RIDGE
IS NOTED W OF THE TROUGH ALONG 128W N OF 25N. MODERATE SUBSIDENCE
WITH LEADING TO RATHER STABLE CONDITIONS THROUGH THE ATMOSPHERE
COVERS THE AREA FROM 20N TO 28N E OF 130W...AND N OF 13N W OF 
130W. A HIGHLY-AMPLIFIED DEEP LAYER MOVING E NEAR 25 KT IS JUST 
NE OF THE AREA. THE UPPER FLOW IS PRETTY ZONAL FROM 20N TO 28N E 
OF THE TROUGH. A HIGHLY-AMPLIFIED DEEP LAYER TROUGH IS NW OF THE
REGION PROGRESSING ESE. ITS ASSOCIATED SURFACE COLD FRONT IS 
RATHER STRONG FOR LATE SUMMER AS OBSERVED ON SATELLITE IMAGERY
WHERE COLD-AIR STRATOCUMULUS CLOUDS ARE EVIDENT TO ITS NW WELL
N OF THE REGION. THE COLD FRONT IS FORECAST TO APPROACH THE FAR 
NW CORNER OF THE AREA LATE TUE PRECEDED BY INCREASING SLY WINDS 
AND BUILDING SEAS BUT THE HIGHEST OF THESE CONDITIONS ARE 
EXPECTED
TO STAY N OF THE AREA PER LATEST GLOBAL MODEL AND WAVEWATCH 
GUIDANCE. SEAS POSSIBLY UP TO 10 FT IN LONG PERIOD NW SWELLS
ARE EXPECTED TO IMPACT THE FAR NW CORNER IN ABOUT 48 HOURS. AT
THE SURFACE...A WEAK RIDGE EXTENDS SE FROM A 1020 MB HIGH 
32N129W TO 23N115W. THE WEAK REMNANT LOW OF LINDA IS NEAR 20N136W
WITH A PRES OF 1012 MB DRIFTING W. IT IS VOID OF ANY DEEP 
CONVECTION
...AND ONLY OCCASIONAL NE WINDS TO 20 KT ARE N OF IT TO 24N.

TO THE S AND SE OF THE MODERATE SUBSIDENCE AREA AMPLE DEEP 
ATMOSPHERIC MOISTURE NOTED AS DEEP MOISTURE FROM THE MONSOONAL 
GYRE DESCRIBED UNDER SPECIAL FEATURE SECTION...AND DEBRIS 
MOISTURE
FROM CONVECTION OVER MEXICO AND CENTRAL AMERICA. THIS MOISTURE IS
BEING ADVECTED WESTWARD ALONG THE SRN PERIPHERY OF THE MID/UPPER 
RIDGE THAT EXTENDS FROM THE ANTICYCLONE NEAR 20N108W TO 
NEAR 123W WHERE THE ENVIRONMENT BECOMES DRY AND STABLE NOTED AS 
MODERATE SUBSIDENCE IN WATER VAPOR IMAGERY FROM THROUGHOUT THE 
DAY.

$$
AGUIRRE