000
AXPZ20 KNHC 070918
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON MAY 07 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0845 UTC.

...ITCZ...
INTERTROPICAL CONVERGENCE ZONE ALONG 6N77W 9N92W 8N101W 11N118W 
10N126W 6N140W. ISOLATED STRONG CONVECTION CENTERED NEAR 6N82W 
7N99W AND 10N111W. ISOLATED MODERATE NEAR 10N107W. AREA OF 
SCATTERED STRONG CONVECTION BETWEEN 8N AND 12N FROM 115W TO 
122W. AREA OF MODERATE CONVECTION WITHIN 45 NM OF 8N127W.

...DISCUSSION...

A STRONG UPPER TROUGH OVER THE SW CONUS TONIGHT CONTINUES TO BE 
QUITE ACTIVE. A NEW SURGE IS DROPPING SWD ALONG 117W OVER NW 
BAJA..PROBABLY THE LAST GASP BEFORE THE WHOLE SYSTEM WEAKENS. 
ALREADY A LOT OF THE TROUGH'S ENERGY IS LIFTING NE. THE OLD 
BLOCKING RIDGE JUST NW OF THE REGION HAS SHIFTED SOME EWD AND IS 
CENTERED TONIGHT NEAR 35N133W. WEAK MID LEVEL TROUGHING EXTENDS 
FROM THE SURGE OVER NW BAJA BACK WSW TO 22N140W. THIS TROUGH HAS 
BEEN INTERCEPTING WEAK IMPULSES ORIGINATING OVER THE S CENTRAL 
PACIFIC. ANOTHER FLAT MID LEVEL RIDGE COVERS THE AREA BETWEEN 
90W AND 110W OVER SRN MEXICO. ON THE SURFACE TONIGHT THE PACIFIC 
RIDGE OF HIGH PRES HAS SHIFTED NWD AS THE UPPER CENTER WEAKENED. 
THUS NE TRADES HAVE WEAKENED SOME. QUIKSCAT STILL SHOWS WINDS 20 
TO 25 KT BETWEEN 10N AND 20N W OF 135W WHILE SSMI SHOWS MAINLY 
20 KT. A NEW AREA OF NE WINDS 20 TO 25 KT SHOWS UP IN QUIKSCAT N 
OF 25N BETWEEN 130W AND 136W. SSMI ALSO SHOWS THIS AREA BUT 
SLIGHTLY WEAKER. WINDS ALONG THE BAJA COAST HAVE DECREASED TO 
MOSTLY LIGHT NWLY. GAP WINDS ARE ALSO LIGHT AND VARIABLE 
TONIGHT. 

LATER DAY 1 THE GFS MODEL IS SHOWING THE SURGE WRAPPING AROUND 
THE BASE OF THE UPPER TROUGH. THIS MAY CLOSE OFF THE SYSTEM OVER 
THE NEXT 24 HR. THE EXTENDED TROUGH WSW TO 20N140W WEAKENS BUT 
THE MODEL STILL SHOWS WEAK IMPULSES MOVING ENE FROM THE S 
CENTRAL PACIFIC. OTHERWISE LITTLE CHANGE TO THE TWO MID LEVEL 
RIDGES..ONE NW OF THE AREA AND THE OTHER OVER SRN MEXICO. ON THE 
SURFACE LATER DAY 1 THE PACIFIC RIDGE CONTINUES TO WEAKEN WITH 
NE TRADES WEAKENING TO 15 TO 20 KT. THE AREA OF NE WINDS N OF 
25N DECREASES AS DOES SEAS. WINDS ALONG THE BAJA COAST BECOME 
LIGHT AND VARIABLE LESS THAN 10 KT BUT NW SWELL OF 6 TO 8 FT 
WILL PREVAIL. GAP WINDS REMAIN LIGHT. 

FOR DAY 2 THE UPPER TROUGH IS FORECAST TO CLOSE OFF WITH A 
CENTER OVER SW AZ. IT'S CIRCULATION WILL COVER THE AREA N OF 23N 
BETWEEN 100W AND 118W. THE GFS MODEL SHOWS MORE ENERGY SLIPPING 
INTO THE SRN BRANCH OF THE WESTERLIES AND DEVELOPING A TROUGH 
NEAR 22N130W. THIS SYSTEM WILL MOVE SLOWLY NE. THE OLD BLOCKING 
RIDGE NW OF THE AREA DISSIPATES AS THE NRN BRANCH OF THE 
WESTERLIES DIG CYCLONICALLY TOWARD THE AREA FROM THE NW. THE 
FLAT MID LEVEL RIDGE OVER THE SE PORTION OF THE AREA ENLARGES 
AND COVERS THE AREA BETWEEN 90W AND 120W AND EXTENDS NE OVER NE 
MEXICO. ON THE SURFACE DAY 2 THE PACIFIC RIDGE WILL CONTINUE TO 
WEAKEN AS THE UPPER CENTER DISSIPATES. THE MODEL HINTS AT SOME 
SORT OF TROUGHING AT THE SURFACE TAKING PLACE BETWEEN 120W AND 
130W PROBABLY AS A RESULT OF THE DEVELOPING TROUGH ALOFT. 
OTHERWISE WINDS REMAIN LIGHT ALONG THE BAJA COAST AND THROUGH 
THE GAP AREAS ALONG THE CENTRAL AMERICAN COASTS. 

$$
RRG