000
AXPZ20 KNHC 281603
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE SEP 28 2010

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 
1545 UTC.

...ITCZ...

AXIS CENTERED ALONG 12N88W 8N98W 10N110W 10N125W 11N130W
11N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
WITHIN 60 NM S OF THE AXIS W OF 137W. SCATTERED MODERATE IS
WITHIN 60 NM S OF THE AXIS BETWEEN 135W-137W.

...DISCUSSION...

W OF 125W...

MID/UPPER LEVEL ANTICYLONE NEAR 20N135W WAS BEING SHUNTED 
SOUTHWARD FOR THE TIME BEING AS A RATHER VIGOROUS SHORTWAVE 
TROUGH WAS APPROACHING THE FAR NW CORNER OF THE REGION. THE 
ASSOCIATED COLD FRONT WAS ABOUT 130 NM NW OF 32N140W. SW UPPER 
LEVEL FLOW WAS INCREASING AHEAD OF THE TROUGH IN A VERY 
PRONOUNCED JET STREAM WITH WINDS OF 35-55 KT. SATELLITE WATER 
VAPOR IMAGERY DEPICTED MODERATE SUBSIDENCE OVER THIS PORTION OF 
THE REGION RESULTING IN STABLE ENVIRONMENTAL CONDITIONS WITH 
SCATTERED TO BROKEN STRATOCUMULUS CLOUDS NOTED N OF 19N...AND 
LIMITING MOISTURE IN THE TROPICAL ZONE. CONVECTION THAT WAS 
OCCURRING ALONG THE ITCZ WAS BEING AIDED BY DIFFLUENT FLOW
ON THE SW PERIPHERY OF THE ANTICYCLONE.

E OF 125W...

A MID/UPPER LEVEL CYCLONIC CIRCULATION WAS OVER THE FAR NE PART
NEAR 31N119W MOVING WNW AT 15 KT. A TROUGH EXTENDS SW FROM THE 
CIRCULATION TO A COL REGION AT 23.5N126W. THE CIRCULATION AND
ITS ASSOCIATED TROUGH WERE BEING SQUEEZED IN BETWEEN THE 
ANTICYCLONE NEAR 20N135W...AND A MUCH LARGER ANTICYCLONE 
ANCHORED OVER THE WESTERN U.S. THE ANTICYCLONIC FLOW ON THE 
SOUTHERN PERIPHERY OF THE LARGE ANTICYCLONE WAS COMBINING WITH 
THAT TO THE N AND NE OF THE CYCLONIC CIRCULATION TO ADVECT AMPLE 
MID/UPPER LEVEL MOISTURE FROM DEEP CONVECTION OVER WESTERN AND 
CENTRAL MEXICO NORTHWESTWARD TOWARDS NORTHERN BAJA CALIFORNIA 
AND SOUTHERN CALIFORNIA INCLUDING THE WATERS OF THE FAR NE 
PORTION OF THE AREA. A MID/UPPER LEVEL ANTICYCLONE WAS CENTERED 
ALONG THE COAST OF MEXICO NEAR 21N106W WITH A RIDGE W TO NEAR 
21N126W...AND ANOTHER RIDGE ESE ACROSS SOUTHEASTERN MEXICO AND 
THE FAR WESTERN CARIBBEAN SEA. THE ANTICYCLONE WAS SUPPORTING 
CONVECTION THAT HAD DEVELOPED ASSOCIATED WITH A SURFACE
1006 MB LOW NEAR 19N107W. THE LOW WAS ASSOCIATED WITH A BROAD 
AREA OF LOW PRES SITUATED A COUPLE OF HUNDRED MILES W OF 
MANZANILLO. THIS AREA LIES UNDER ONLY MARGINALLY FAVORABLE UPPER
LEVEL WINDS...SO THE CHANCE IS LOW FOR IT TO BECOME A TROPICAL 
CYCLONE OVER THE NEXT 48 HOURS.

OF MARINE RELATE ISSUES...SW TO W WINDS OF 20 TO 25 KT PRESENT 
FROM 8 TO 14N E OF 100W WERE SERVING AS INFLOW INTO NEWLY FORMED
TROPICAL DEPRESSION SIXTEEN IN THE NORTHWESTERN CARIBBEAN SEA 
WITH THE DEPRESSION FORECAST TO MOVE NE OVER THE NEXT 48 
HOURS...THESE WINDS WILL DIMINISH SOME IN COVERAGE. A COLD FRONT 
MOVING THROUGH THE EASTERN BAY OF CAMPECHE WILL INDUCE FRESH TO 
STRONG FLOW THROUGH THE GULF OF TEHUANTEPEC LATER TODAY...AND 
LAST THROUGH THE NEXT 240-36 HOURS. AN ASCAT PASS FROM 04Z 
SHOWED FAIRLY LIGHT FLOW AROUND THIS SYSTEM. ELSEWHERE...15-17 
SEC LONG PERIOD SWELL CONTINUES TO PUSH SE FROM THE N CENTRAL 
PACIFIC IN TO THE DISCUSSION AREA. ALTIMETRY DATA SHOWS SEAS 
BEGINNING TO SUBSIDE FROM A MAX OF 13 FT OVER NW WATERS FROM 
THIS SWELL TRAIN. THIS INITIAL SWELL TRAIN WILL CONTINUE TO 
SPREAD SE ACROSS NW HALF OF THE BASIN AND GRADUALLY SUBSIDE... 
WHILE A SECOND SURGE OF NW SWELL WILL REACH FAR NW WATERS TUE 
AND BRING THE SEAS BACK TO THE 10 TO 13 FT RANGE THIS AFTERNOON. 
LOOKING AHEAD...LONG PERIOD SW SWELL OF UP TO 15 FT IS FORECAST 
TO PROPAGATE TOWARD THE CENTRAL AMERICAN COAST BY THE WEEKEND.

$$
AGUIRRE