000
AXPZ20 KNHC 121554
TWDEP 

TROPICAL WEATHER DISCUSSION     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON MAR 12 2007

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1545 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 4N77W 4N92W 3N98W 7N112W 4N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 60 NM 
EITHER SIDE OF LINE 6N77W 4N94W 2N88W AND WITHIN 75 NM EITHER 
SIDE OF LINE 5N89W 3N101W. SCATTERED MODERATE CONVECTION IS 
OBSERVED WITHIN 30 NM EITHER SIDE OF LINE 9N112W 4N124W 4N136W.

...DISCUSSION...

A MID TO UPPER LEVEL ANTICYCLONE IS AT 24N131W WITH A SHORTWAVE 
RIDGE EXTENDING N AND CRESTING OVER NW CONUS. AN UPPER CYCLONE 
IS JUST W OF THE AREA AT 34N142W WITH A TROUGH S TO A BASE NEAR 
14N145W. DRY UPPER AIR ACCOMPANIES THE TROUGH WHILE BAND OF 
UPPER MOISTURE IS TRAPPED E OF THE TROUGH AND ALONG THE W 
PERIPHERY OF THE ANTICYCLONE...ROUGHLY WITHIN 90 NM EITHER SIDE 
OF LINE 20N141W 32N137W. FURTHER E...A BROAD SHORTWAVE TROUGH 
OVER THE WESTERN CONUS EXTENDS SW INTO THE AREA THROUGH UPPER 
CYCLONES AT 32N103W AND 20N118W WITH A TROUGH EXTENDING SW TO 
NEAR 5N131W. A SMALL AREA OF UPPER MOISTURE IS NOTED WITHIN 120 
NM OF 21N113W...OTHERWISE...DRY UPPER AIR IS INDICATED N OF THE 
ITCZ W OF 116W.

AN UPPER ANTICYCLONE WELL E OF THE AREA NEAR 3N59W HAS BECOME 
DOMINATE WITH A RIDGE EXTENDING W ACROSS CENTRAL AMERICA TO NEAR 
10N107W. A MOISTURE PLUME...ORIGINATING FROM ITCZ CONVECTION 
BETWEEN 101W AND 135W...IS NOTED WITHIN 360 NM EITHER SIDE OF 
LINE FROM 10N106W TO 25N88W...THEN THE PLUME NARROWS AND 
SOMEWHAT EVAPORATES AS IT TURNS E IN UPPER ZONAL FLOW ACROSS THE 
RIDGE OVER THE EASTERN GULF OF MEXICO. 

AN UPPER TROUGH IS NOTED OVER THE TROPICAL E PAC S OF 8N ALONG 
82W. OVERALL...THE UPPER FLOW IS DIFFLUENT S OF 8N E OF 103W 
WITH SLIGHT ENHANCEMENT OF THE NORTHERN HEMISPHERE ITCZ.

AT THE LOW LEVELS...SURFACE HIGH PRES IS STATIONARY NEAR 34N134W 
WITH BROAD HIGH PRES DOMINATING THE DISCUSSION AREA N OF THE 
ITCZ.

GAP WINDS...GULF OF TEHUANTEPEC...N-NE WINDS 20 TO 25 KT WILL 
BEGIN AGAIN ON TUE THEN DIMINISH ABOUT 20 KT WED. NE WINDS 20 TO 
25 KT CONTINUE IN AND DOWNSTREAM OF THE GULF OF PAPAGAYO AND 
EXTEND N TO INCLUDE MOST OF THE AREA DOWNWIND OF THE GULF OF 
FONSECA...WITH LITTLE CHANGE EXPECTED FOR AT LEAST 48 HOURS WITH 
MODELS HINTING AT SURGES TO 30 KT. 

$$
NELSON