000
AXPZ20 KNHC 062158
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI APR 06 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N83W 7N100W 4N120W 3N140W. 
SCATTERED MODERATE ISOLATED STRONG WITHIN 90 NM OF THE AXIS 
BETWEEN 98W AND 110W...WITHIN 120-150 NM OF THE AXIS E OF 94W.

...DISCUSSION...

A PROGRESSIVE PATTERN DOMINATES THE AREA WITH MID/UPPER LEVEL 
RIDGING EARLIER EXTENDING NORTH TO SOUTH ACROSS BAJA NOW SHIFTED 
TO OVER CENTRAL MEXICO ALONG 103W...AND A CUT-OFF MID/UPPER LOW 
OVER SOUTHEAST CALIFORNIA. FURTHER W...RATHER VIGOROUS MID/UPPER 
LEVEL TROUGH IS GRAZING THE EXTREME NORTHWEST CORNER OF THE 
DISCUSSION AREA. A MID/UPPER LEVEL SHEARED TROUGH TRAILS SOUTH 
FROM THE LOW THROUGH NORTHERN BAJA THEN SOUTHWEST TO 16N117W TO 
22N122W. CONFLUENT FLOW TO THE WEST OF THE TROUGH IS RESULTING 
DRY STABLE AIR BEHIND THE TROUGH TO A LINE FROM 32N130W TO 
15N136W TO 23N140W AS EVIDENT IN THE MODERATE TO SUBSIDENCE 
DISPLAYED ON WATER VAPOR IMAGERY. A SUBTROPICAL JET STREAM 
BRANCH ENTERS THE WESTERN PART OF THE DISCUSSION AREA THROUGH 
16N140W...AND EXTENDS NORTHEAST ROUNDING THE SOUTHERN PERIMETER 
OF THE TROUGH ALONG 19N130W 22.5N120.5W TO ACROSS CENTRAL BAJA 
CALIFORNIA AND TO NORTHERN MEXICO. AMPLE DEEP TROPICAL MOISTURE 
SEEN IN THE FORM OF BROKEN CIRRUS CLOUDS WITHIN 450 NM SOUTHEAST 
OF THE JET STREAM ARE SUGGESTING TRANSVERSE BANDING BETWEEN 
114W-123W. RIPPLES OF ENERGY ALONG THE JET STREAM ARE 
PROPAGATING QUICKLY TO THE NORTHEAST MAINLY EAST OF 132W WHERE 
SATELLITE DERIVED UPPER AIR DATA INDICATED MAXIMUM JET CORE 
WINDS IN THE RANGE OF 80-100 KT.

THE NEXT COLD FRONT TO MOVE INTO THE REGION WILL BE ASSOCIATED 
WITH THE AFOREMENTIONED TROUGH NOTED ABOVE...AND IS JUST 
ENTERING THE FAR NORTHWEST CORNER...BUT IS WEAKENING WITH 
TIME. SOUTHWEST WINDS OVER THE NW PART ARE IN THE 20-25 KT RANGE
WITH LARGE NW SWELL SPREADING INTO THE AREA. WINDS THEN DIMINISH 
IN ABOUT 24 HRS...HOWEVER THE SWELLS REMAIN. OVERCAST MOSTLY MID 
AND UPPER LEVEL CLOUDS ASSOCIATED WITH THE MID/UPPER TROUGH ARE 
ALREADY IMPACTING THE AREA NORTH OF 25N WEST OF 128W. BROKEN LOW 
CLOUDS WITH WIDELY SCATTERED SHOWERS ARE JUST NORTHWEST OF THE 
AREA ALONG AND NEAR THE FRONT...AND ARE EXPECTED TO MOVE INTO 
THE NORTHWEST PART THIS AFTERNOON WITH THE FRONT.

THE MID/UPPER LEVEL FLOW JUST WEST OF THE AREA BECOMES SHARPLY
NORTHWEST TO NORTH DUE TO LARGE MID/UPPER ANTICYCLONIC HIGH WEST
SITUATED WELL TO THE WEST OF 140W.

A MID/UPPER LEVEL TROUGH AXIS IS SEEN ON WATER VAPOR IMAGERY 
EXTENDING FROM ROUGHLY 11N106W SOUTHWEST TO BEYOND THE EQUATOR
AT 110W. THIS TROUGH IS ENHANCING ITCZ CONVECTION EAST OF TROUGH
FROM 4N-7N EAST OF 94W. MID/UPPER LEVEL RIDGING EXTENDS ALONG 6N
TO THE EAST OF THE TROUGH SUPPORTING CONVECTION ELSEWHERE ALONG 
THE ITCZ EAST OF 98W. THE TROUGH IS FORECAST TO MOVE EAST THROUGH
SAT THEN DISSIPATE LATE SAT INTO SUN. BROAD MID/UPPER LEVEL 
ANTICYCLONIC FLOW COVERS THE AREA SOUTH OF 10N WEST OF THE 
TROUGH. CONVECTION IS ALSO ACTIVE ALONG THE ITCZ FROM 4N-6N 
BETWEEN 125W-128W.

GAP WINDS...NO UPDATED QUIKSCAT DATA WAS AVAILABLE THIS MORNING 
FOR THE DISCUSSION AREA...HOWEVER NWP MODEL DATA SUGGESTS THE 
MINIMAL GALE ACROSS THE GULF OF TEHUANTEPEC HAS ENDED WITH WINDS
DIMINISHING TO LESS THAN 20 KT IN ABOUT 36 HOURS. PAPAGAYO WINDS 
MAY BRIEFLY INCREASE TO 20 KT SAT MORNING AND AGAIN SUN MORNING 
DUE TO THE WIND REGIME ACROSS COSTA RICA ENHANCED BY SLIGHT 
TIGHTENING OF THE GRADIENT AND INTERACTING UPON THE LOCAL 
GEOGRAPHY FOUND THERE.

$$
COBB