000
AXPZ20 KNHC 170921
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU MAY 17 2007

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0845 UTC.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N80W 10N110W 7N121W 7N133W 6N140W. 
SCATTERED MODERATE TO STRONG CONVECTION N OF 5N E OF 85W ALSO 
FROM 5N TO 9N BETWEEN 91W AND 97W. ISOLATED STRONG NEAR 10N122W. 
SCATTERED MODERATE CONVECTION WITHIN 25 NM EITHER SIDE OF A LINE 
FROM 7N124W TO 6N137W. 

...DISCUSSION...

THE SRN BRANCH OF THE WESTERLIES HAS STRENGTHENED SOME DURING 
THE PAST 48 HRS. THE MID LEVEL FLOW ORIGINATES JUST S OF 20N 
HEADS E THEN TURNS ENE AND CROSSES BAJA. WEAK IMPULSES ARE 
EMBEDDED IN THE SRN BRANCH..ONE OF WHICH IS ALONG 120W AND 
ANOTHER APPROACHING 20N140W. THE FLAT MID LEVEL RIDGE COVERING 
THE AREA S OF 20N CONTINUES TO BULGE NWD ALONG 105W OVER NRN 
MEXICO. A STRONG DIGGING MID LEVEL TROUGH IS APPROACHING THE NW 
CORNER OF THE REGION TONIGHT. ON THE SURFACE TONIGHT THE PACIFIC 
RIDGE IS ANCHORED BY A 1026 MB HIGH CENTER NEAR 29N135W. THE 
RIDGE EXTENDS SE TO 12N100W. THE RIDGE IS PRODUCING NE TRADES 20 
TO 25 KT W OF 125W. NW WINDS ALONG THE BAJA COAST ARE 15 TO 20 
KT ACCORDING TO SSMI. NO QUIKSCAT PASS. GAP WINDS ARE MOSTLY 
LIGHT. TEHUANTEPEC WINDS AROUND 15 KT.

LATER DAY 1 LITTLE CHANGE TO THE OVERALL MID LEVEL PATTERN. EVEN 
THE TWO WEAK IMPULSES IN THE SRN BRANCH MOVE VERY LITTLE. 
PROBABLY INFLUENCED BY THE LOWERING MID LEVEL HEIGHT FIELD TO 
THE NW. ON THE SURFACE LATER DAY 1 THE PACIFIC RIDGE CENTER 
DRIFTS E TO NEAR 29N133W AND REMAINS NEAR 1026 MB. NE TRADES 
DECREASE SOME ACCORDING TO THE GFS MODEL TO 20 KT W OF 125W. 
BAJA WINDS REMAIN THE SAME..NWLY 15 TO 20 KT. TEHUANTEPEC WINDS 
OCCASIONALLY 20 KT. 

FOR DAY 2 THE GFS MODEL SHOWS THE FIRST IMPULSE IN THE SRN 
BRANCH STALLING OFF THE BAJA COAST..APPARENTLY GETTING SOME 
INPUT FROM THE NRN BRANCH AS THE BIG TROUGH BRUSHES BY TO THE 
NW. THIS GIVES THE SECOND WEAK IMPULSE A CHANCE TO CATCH UP WITH 
THE FIRST ONE WHICH ENABLES MID LEVEL TROUGHING TO DEVELOP ALONG 
115W. OTHERWISE THE FLAT MID LEVEL RIDGE HOLDS FIRM S OF 20N 
STILL BULGING NWD ALONG 105W. ON THE SURFACE DAY 2 PRETTY MUCH A 
CARBON COPY OF DAY 1 WITH A 1026 MB HIGH CENTER NEAR 29N132W AND 
SIMILAR WINDS N OF 10N W OF 110W. GAP WINDS THROUGH TEHUANTEPEC 
INCREASE SLIGHTLY 20 TO 25 KT AS A LARGE RIDGE OF HIGH PRES SITS 
OVER THE WRN GULF. SOME INCREASE IN SW WINDS TO 20 KT S OF 5N E 
OF 90W WITH SEAS 6 TO 8 FT.

$$
RRG