000
AXPZ20 KNHC 080311
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU OCT 08 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 101W N OF 7N TO JUST INLAND
THE MEXICAN COAST. IT WAS MOVING W ABOUT 18 KT. THE WAVE 
CONTINUES TO BE EMBEDDED WITHIN A BROAD LOW TO MID LEVEL 
ELONGATED CYCLONIC GYRE SEEN AS DEEP LAYER MOISTURE IN THE TOTAL 
PRECIPITABLE WATER IMAGERY. A SWATH OF E-SE 20 KT WINDS... 
INITIATED MAINLY BY MOMENTUM OF WRN CARIBBEAN TRADES...
WAS NOTED IN SCATTEROMETER DATA FROM EARLIER TODAY E OF THE WAVE 
TO NEAR 91W. SIMILAR WINDS WERE OBSERVED ALONG THE COAST OF
SE MEXICO ADJACENT TO THE GULF OF TEHUANTEPEC...AND COAST
OF GUATEMALA. WITHIN THIS CYCLONIC GYRE...CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE NOTED FROM 12N TO 16N 
BETWEEN 95W AND 106W. ALTHOUGH GLOBAL MODELS ARE NOT VERY 
CONSISTENT REGARDING FUTURE DEVELOPMENT OF THIS SYSTEM...THEY 
INDICATE THAT PERHAPS A MORE DEFINITIVE LOW PRES SYSTEM COULD BE 
IN THE VICINITY OF 105W WITHIN 48 HOURS. 

...ITCZ...

THE ITCZ AXIS WAS CENTERED ALONG 8N78W TO 9N90W T0 11N101W TO 
12N110W TO 10N120W TO 9N130W TO 7N140W. SCATTERED MODERATE TO 
STRONG CONVECTION WAS WITHIN 60 NM S OF THE AXIS BETWEEN 110W
-118W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION WAS WITHIN
120 NM S OF THE AXIS BETWEEN 130W-136W. SCATTERED MODERATE 
CONVECTION WAS WITHIN 120 NM S OF THE AXIS BETWEEN 118W-121W.

...DISCUSSION...

A BROAD ANTICYCLONIC CIRCULATION E OF THE AREA OVER THE NRN
GULF OF MEXICO EXTENDS A RIDGE SW TO ACROSS CENTRAL MEXICO
TO 19N110W TO NEAR 15N120W. THIS RIDGE WILL SHIFT E AND 
WEAKEN...AHEAD OF A MID TO UPPER LEVEL TROUGH THAT STRETCHES 
FROM A MID/UPPER LEVEL UPPER LEVEL LOW N OF THE AREA OVER 
SRN CALIFORNIA SSW THROUGH 32N118W...THEN S TO 24N120W TO A
COL REGION NEAR 15N124W WHICH IS IN BETWEEN THE ABOVE MENTIONED
RIDGE AND AN ELONGATED MID/UPPER LEVEL ANTICYCLONIC CIRCULATION
MOVING E NEAR 15N135W. A 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 CALIFORNIA AND ACROSS
NRN MEXICO AND THE SRN U.S. A BROAD SWATH OF OF UPPER LEVEL
MOISTURE IN THE FORM OF BROKEN CIRRUS CLOUDS WAS RIDING UP
AND OVER THE RIDGE ALONG 135W...AND SPREADING ESE TO NEAR 
130W WHERE IT WAS ERODING IN A VERY STABLE ENVIRONMENT NOTED
BY MODERATE SUBSIDENCE IN WATER VAPOR IMAGERY. THIS SECOND 
ANTICYCLONE IS FORECAST TO SHIFT EASTWARD AS A LARGE DEEP LAYER 
TROUGH WELL W OF THE AREA MIGRATES ENE. A STRONGER JET STREAM 
BRANCH...WITH MAXIMUM JET CORE WINDS OF 90 KT...WAS ROUNDING THE 
BASE OF THIS TROUGH...AND ENTERING THE FAR WRN PORTION OF THE 
REGION THROUGH 27N140W AND DIVING SEWD TO NEAR 22N127W.

A SURFACE RIDGE ENTERS THE REGION THROUGH 32N135W AND EXTENDS SE 
TO NEAR 22N116W. A SHIP W OF THE BAJA CALIFORNIA COAST ON THE
ERN PERIPHERY OF THE RIDGE NEAR 24N113W WITH CALLER ID "NWS0002" 
REPORTED A NW WIND OF 20 KT DUE TO A TIGHTER PRES GRADIENT IN
THE FAR E SECTION OF THE AREA DUE TO THE RIDGE BUILDING SE.
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 1010 MB LOW IS NOTED ALONG THE ITCZ
NEAR 112W. THE LOW IS FORECAST TO MOVE W OVER THE NEXT COUPLE OF 
DAYS AS IT INTERACTS WITH THE RIDGE TO THE N...HOWEVER MAIN AREA
OF CONCERN WITH RESPECT TO WINDS WITH THIS LOW WILL BE WITHIN 
180 NM IN ITS SE QUADRANT WHERE 20 KT WINDS ARE OCCURRING. THESE
CONDITIONS ARE EXPECTED TO CHANGE LITTLE OVER THE NEXT 48 HOURS.
TO THE N OF THE LOW...NE TRADES OF 20 KT WERE SEEN FROM 13N TO 
20N BETWEEN 115W AND 134W WITH SEAS TO 9 FT WITH WIND WAVES. 
THESE SEAS ARE FORECAST BY LATEST WAVEWATCH MODEL GUIDANCE TO 
BUILD UP POSSIBLY 10 FT FOR A SHORT DURATION ON THU...THEN 
SUBSIDE 8 TO 9 FT BY FRI NIGHT.

A SURFACE TROUGH FORMED TODAY TO THE S OF THE RIDGE FROM 10N127W 
TO 15N121W. IT SEPARATES NE TRADE WIND FLOW OF 15-20 KT FROM
LIGHTER NE-E WINDS OF 10-15 KT TO ITS SE. SCATTERED DEEP 
CONVECTION EARLIER NOTED TO THE E OF THE TROUGH HAS RECENTLY 
WEAKENED...AND ONLY WIDELY SCATTERED SHOWERS AND TSTMS WERE 
NOTED WITHIN 150 NM E OF THE TROUGH.

$$
AGUIRRE