000
AXPZ20 KNHC 090332
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI OCT 09 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.

...TROPICAL WAVE... 

A TROPICAL WAVE WAS ANALYZED ALONG 106W FROM 7N TO 18N...AND
ESTIMATED TO BE MOVING W ABOUT 15 KT. THIS WAVE HAS ENTERED THE 
EASTERN END OF A BROAD AND ELONGATED LOW TO MID LEVEL CYCLONIC 
GYRE DURING THE PAST 24-48 HOURS...MAKING ITS PRECISE LOCATION 
SOMEWHAT COMPLEX. THE WAVE IS UNDER THE DIFFLUENT ALOFT REGION 
OF AN UPPER SHORTWAVE TROUGH DESCRIBED BELOW. THE UPPER 
DIFFLUENCE IS SUPPORTING CONVECTION ALONG THE THE WAVE 
AXIS...AND WITHIN THIS AREA OF LOW PRES. SCATTERED MODERATE TO 
STRONG CONVECTION IS WITHIN AN AREA BOUNDED FROM 12N TO 16N 
BETWEEN 96W AND 101W. E TO SE WINDS OF 20 KT WITH SEAS TO 8 FT 
ARE OCCURRING FROM 13N TO 16N BETWEEN 95W AND 103W...HOWEVER 
WINDS AND SEAS MAY BE HIGHER IN AND NEAR THE CONVECTION. LAST 
VISIBLE SATELLITE IMAGERY SHOWED WHAT APPEARS TO BE THE 
BEGINNING SIGNS OF DEVELOPING LOW PRES ALONG THE WAVE NEAR 18N. 
GLOBAL MODELS SUGGEST THAT THIS MAY BE THE AREA OF LOW THAT WILL 
BECOMES MORE DEFINITIVE E DURING THE NEXT 2-3 DAYS AS IT TRACKS 
NW. THE ECMWF MODEL GUIDANCE STILL APPEARS THE MOST AGGRESSIVE 
MODEL WITH THIS SYSTEM. 

...ITCZ...

THE ITCZ AXIS WAS CENTERED ALONG 8N78W TO 9N90W TO 11N100W TO
12N110W TO 12N120W TO 11N129W TO 6N140W. SCATTERED STRONG 
CONVECTION IS WITHIN 120 NM S OF THE AXIS BETWEEN 100W-102W
...WITHIN 60 NM OF THE AXIS E OF 84W...AND ALSO BETWEEN 94W-96W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION WAS WITHIN 120 NM 
S OF THE AXIS BETWEEN 127W-138W.

...DISCUSSION...

A BROAD ANTICYCLONIC CIRCULATION E OF THE AREA OVER THE NRN
GULF OF MEXICO EXTENDS A RIDGE SW TO ACROSS CENTRAL MEXICO TO 
NEAR 16N116W. THIS RIDGE WILL SHIFT E AND WEAKEN...AHEAD OF A 
STRONG DEEP LAYER TROUGH THAT STRETCHES FROM THE SW U.S. SSW
TO 21N113W. TO THE W OF THE TAIL END OF THIS TROUGH IS A 
MID/UPPER LEVEL ANTICYCLONIC CIRCULATION NEAR 15N135W...WITH A 
BROAD RIDGE EXTENDS NORTHWARD FROM THIS ANTICYCLONE TO N OF THE 
AREA AT 32N135W. A SWLY JET STREAM BRANCH BETWEEN THE FIRST 
RIDGE AND TROUGH AS SEEN IN WATER VAPOR IMAGERY WILL CONTINUE TO 
ADVECT UPPER LEVEL MOISTURE IN THE FORM OF SCATTERED THIN CIRRUS 
ACROSS SRN BAJA CALIFORNIA AND CENTRAL MEXICO...WHILE MORE 
SIGNIFICANT CONVECTIVE DEBRIS WAS BEING PULLED N AND NE FROM THE 
W COAST OF MEXICO ACROSS THE BORDER OF MEXICO AND SW TEXAS. TO
THE W AND NW OF THE TROUGH TO NEAR 123W MODERATE SUBSIDENCE 
LEADING TO RATHER STABLE ENVIRONMENTAL CONDITIONS ARE NOTED.

S OF THE GULF OF MEXICO RIDGE WAS A TUTT LOW OVER CENTRAL 
AMERICA CENTERED NEAR 14N89W AND SHIFTING W INTO THE EPAC. UPPER 
DIVERGENCE TO THE W OF THIS LOW WAS VENTILATING AND SUSTAINING 
WIDELY SCATTERED MODERATE CONVECTION ALONG THE SE COAST OF 
MEXICO ASSOCIATED WITH THE CYCLONIC GYRE MENTIONED ABOVE.

A SURFACE RIDGE ENTERS THE REGION THROUGH 32N135W AND EXTENDS SE 
TO NEAR 22N116W. A TIGHT PRES GRADIENT E OF THE RIDGE N OF 20N 
IS ALLOWING FOR NW WINDS OF 20 KT FROM 20N TO 27N E OF 116W
TO THE W COAST OF BAJA CALIFORNIA. HOWEVER...THE RIDGE IS 
FORECAST TO WEAKEN AFTER 48 HOURS AS A COLD FRONT APPROACHES THE 
FAR NW CORNER OF THE REGION.

OVER THE SRN PORTION...A TROUGH EXTENDS FROM 8N130W TO 15N128W 
MOVING W 12 KT...AND IS ENHANCING CONVECTION N OF THE ITCZ AS 
DESCRIBED ABOVE. TO THE N OF THE TROUGH...NE TRADES OF 20 TO 
25 KT WITH SEAS OF 8 TO 10 FT WERE NOTED FROM 13N TO 20N BETWEEN 
119W AND 135W WITH NE TO E WINDS OF 20 KT WITH SEAS TO 8 FT FROM 
12N TO 20N ELSEWHERE W OF 115W. THESE SEAS ARE FORECAST BY 
LATEST WAVEWATCH MODEL GUIDANCE TO SUBSIDE TO 8 FT IN 24 
HOURS...AND TO LESS THAN 8 FT THEREAFTER.

$$
AGUIRRE