000
AXPZ20 KNHC 121534
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT SEP 12 2009

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1515 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 107W N OF 5N MOVING W ABOUT 15 KT. 
LATEST SATELLITE IMAGERY IS SHOWING CLUSTERS OF SCATTERED STRONG 
CONVECTION WITHIN 180 NM E OF THE WAVE FROM 15N-19N. SIMILAR 
CONVECTION IS E OF THE WAVE ASSOCIATED WITH THE ITCZ AS 
DESCRIBED BELOW. THIS REMAINS UNDER STRONG ELY SHEAR ACROSS THIS 
PORTION OF THE REGION. ONLY ISOLATED SHOWERS ARE ELSEWHERE 
WITHIN 120 NM EITHER SIDE OF THE WAVE.

A TROPICAL WAVE JUST RECENTLY ENTERED THE AREA...AND IS ANALYZED
ALONG 86W N OF 4N MOVING W AT 15 KT. DEEP CONVECTION ASSOCIATED
WITH THIS IS JUST ABOUT NON-EXISTENT WITH ONLY SCATTERED MODERATE
CONVECTION NOTED WITHIN 30 NM OF 6N86W.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N79W TO 14N95W TO 16N107W TO 
8N120W 7N130W TO 6N140W. SCATTERED STRONG CONVECTION IS
S OF THE ITCZ FROM 8N-10N BETWEEN 100W-107W. SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM S OF THE 
AXIS E OF 84W...AND FROM 9N-13N BETWEEN 93W-100W.

...DISCUSSION...

A MID/UPPER LEVEL TROUGH ENTERS THE REGION FROM SRN CALIFORNIA
SW TO 27N129W TO NEAR 18N140W. TO THE E OF THIS TROUGH MODERATE 
TO STRONG SLY WINDS CONTINUE TO ADVECT DRY AND STABLE CONDITIONS 
INTO THE FAR WESTERN PORTION OF THE AREA NOTED AS MODERATE 
SUBSIDENCE IN THE WATER VAPOR IMAGERY. THE REMNANT LOW
OF LINDA CONTINUES TO BE OBSERVED AS A VERY PRONOUNCED 
CIRCULATION VOID OF DEEP CONVECTION UNDER DEEP SOUTHERLY SHEAR. 
THE CIRCULATION CONSISTS OF BROKEN TO OVERCAST LOW AND MID 
CLOUDS WITH ISOLATED SHOWERS. NE WINDS 20-30 KT ARE OCCURRING
WITHIN 180 NM N AND 90 NM S SEMICIRCLES OF THE CENTER WITH SEAS
8-12 FT.

A NEARLY STATIONARY UPPER ANTICYCLONE IS NEAR 22N114W WITH A 
RIDGE EXTENDING SW ACROSS LINDA AND FURTHER SW TO NEAR 12N140W.
ANOTHER RIDGE EXTENDS E-SE FROM THE ANTICYCLONE TO ALONG THE 
MEXICAN COAST TO THE FAR WESTERN SECTION OF THE GULF OF 
TEHUANTEPEC. THE SURFACE RIDGE EXTENDS SE INTO THE AREA THROUGH
28N140W SE TO NEAR 25N124W. A DEEP MOISTURE PLUME ORIGINATING 
FROM BOTH ITCZ CONVECTION...AND CONVECTION EARLIER OVER 
MEXICO...IS BEING ADVECTED WESTWARD OVER THE SRN PERIPHERY OF 
THE RIDGE TO NEAR 127W WHERE IT ERODES IN THE DRIER AIR. 

A STRONGER AND VERY PROGRESSIVE DEEP LAYER TROUGH IS ENTERING 
THE FAR NW CORNER OF THE REGION THROUGH 32N140W. THIS TROUGH
IS FORECAST BY NWP MODELS TO PUSH A COLD FRONT INTO THE NW 
PORTION OF THE AREA DURING THE WEEKEND BRINGING LARGE LONG 
PERIOD NWLY SWELLS MAXING UP TO 10 OF 11 FT PER LATEST WAVE 
MODEL GUIDANCE. THESE SWELLS SHOULD OVERSPREAD ACROSS THE NW 
PART OF THE AREA THROUGH THE WEEKEND AS THE FRONT WEAKENS OVER 
THE FAR NORTHERN SECTION. HOWEVER...A STRONGER COLD FRONT IS
FORECAST TO MOVE INTO THE NW PORTION OF THE AREA EARLY NEXT WEEK
ALLOWING FOR SEAS TO BUILD AGAIN IN A LARGE NW SWELL TRAIN.

CROSS EQUATORIAL SLY WINDS OF 20 KT AND SWELLS GENERATED BY A 
BROAD FIELD OF SE WINDS 20-25 KT S OF THE EQUATOR WILL CONTINUE 
TO AFFECT THE FAR SOUTHERN PORTION S OF 7N BETWEEN 85W-114W AND 
S OF THE ITCZ E OF 85W.

$$
AGUIRRE