000
AXPZ20 KNHC 130918
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT OCT 13 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...
INTERTROPICAL CONVERGENCE ZONE...AXIS ALONG 9N78W 15N97W 13N105W 
9N116W 11N135W 11N140W. SCATTERED MODERATE CONVECTION ALONG A 
LINE FROM 11N94W TO 14N101W AND FROM 11N101W TO 9N112W. ISOLATED 
STRONG NEAR 14N107W AND 16N107W. ISOLATED MODERATE NEAR 13N109W. 

ISOLATED MODERATE CONVECTION NEAR THE COAST OF COLOMBIA NEAR 
7N78W. SCATTERED STRONG NEAR THE COAST OF CENTRAL AMERICA FROM 
13N88W TO 13N91W TO 14N93W. ISOLATED MODERATE NEAR 17N102W.

...DISCUSSION...

A STRONG UPPER TROUGH ALONG 120W TONIGHT IS MOVING INLAND OVER 
THE WRN CONUS. MAIN JET ENERGY ROUNDING THE BASE OF THE TROUGH 
AT 06Z LOWERING MID LEVEL HEIGHTS BETWEEN 110W AND 120W N OF 
28N. MID LEVEL RIDGE CENTER OVER SRN BAJA WITH RIDGE AXIS NE TO 
CENTRAL PLAINS. MID LEVEL FLOW BECOMES WLY W OF 130W WITH A WEAK 
SHORTWAVE TROUGH ALONG 142W MOVING E. ON THE SURFACE TONIGHT A 
WEAK COLD FRONT WAS OVER THE NRN PORTION OF THE AREA ALONG 29N W 
OF 130W. WINDS WITH THE FRONT ARE LESS THAN 20 KT BUT NW SWELL 
TO 8 FT IS FOLLOWING THE FRONT. THE PACIFIC RIDGE IS WEAK WITH 
LITTLE SUPPORT ALOFT..THUS NE TRADES ARE ALSO WEAK W OF 125W. 
WINDS ALONG THE BAJA COAST WWD TO 118W ARE NWLY 15 TO 20 KT 
ACCORDING TO SSMI AND QUIKSCAT. A WEAK LOW WAS NEAR 15N105W 
MOVING W. GFS MODEL WANTS TO DEVELOP THIS LOW OVER THE NEXT 48 
HR. GAP WINDS ARE LIGHT TONIGHT WITH MOST WINDS ONSHORE. CROSS 
EQUATORIAL SLY WINDS REMAIN GUSTY FROM THE SW N OF 6N TO 11N E 
OF 112W MAINLY DUE TO LOWER PRESSURE ALONG 13N TO 15N E OF 110W.

LATER DAY 1 THE STRONG UPPER TROUGH SLOWLY SHIFTS EWD TO ALONG 
114W. THE MID LEVEL RIDGE HOLDS IT'S OWN CENTERED NEAR 13N106W 
WHILE THE WEAK SHORTWAVE TROUGH MOVES TO 140W IN THE WESTERLIES. 
ON THE SURFACE LATER DAY 1 THE GFS MODEL LIKES THE LOW NEAR 
15N106W WHILE MOVING IT SLOWLY WWD. IT WILL HAVE TO BE WATCHED 
FOR FURTHER DEVELOPMENT IF CONVECTION GETS ORGANIZED. OTHERWISE 
THE COLD FRONT ENTERING THE AREA GRADUALLY DISSIPATES ALONG 27N 
W OF 120W WITH LIGHT WINDS. THE PACIFIC RIDGE REMAINS WEAK WITH 
A 1018 MB CENTER NEAR 24N136W THUS TRADES REMAIN LIGHT. WINDS 
ALONG THE BAJA COAST REMAIN NWLY 15 TO 20 KT BUT ARE TRENDING 
TOWARD WEAKER VALUES. CROSS EQUATORIAL SLY WINDS CHANGE LITTLE 
WITH SW WINDS OF 20 KT CONTINUING FROM 5N TO 11N BETWEEN 90W AND 
110W. GAP WINDS REMAIN LIGHT.

FOR DAY 2 MID LEVEL HEIGHTS FALL N OF 26N OVER MEXICO AS A NEW 
SURGE OF COLD AIR WORKS IT'S WAY AROUND THE UPPER TROUGH THAT IS 
MOVING INLAND OVER THE SWRN CONUS. MID LEVEL RIDGING SHIFTS WWD 
TO 124W WITH A WEAK AXIS NWD TO CENTRAL CA. ANOTHER FAIRLY 
STRONG UPPER TROUGH APPEARS ON THE HORIZON ALONG 137W AND WILL 
LOWER MID LEVEL HEIGHTS W OF 130W N OF 27N. ON THE SURFACE DAY 2 
ALL EYES WILL BE ON THE LOW PRES CENTER WHICH IS FORECAST TO 
MOVE TO NEAR 15N110W. THE GFS MODEL HAS BACKED OFF ON THE FAST 
DEVELOPMENT OF THIS SYSTEM IN IT'S RUNS OF THE PAST TWO 
DAYS..BUT IT WILL STILL HAVE TO BE WATCHED IF CONVECTION GETS 
ORGANIZED. OTHERWISE A NEW COLD FRONT APPEARS ON THE HORIZON 
JUST NW OF THE AREA BUT IT LOOKS A LOT LIKE THE FIRST ONE WITH 
LIGHT WINDS. THE PACIFIC RIDGE REMAINS WEAK WITH NO REAL SUPPORT 
ALOFT AND NE TRADES WILL REMAIN 10 TO 15 KT. WINDS ALONG THE 
BAJA COAST S OF 27N WILL REMAIN 15 TO 20 KT HELPED BY THE LOW 
PRES PASSING TO THE S OF THE AREA. GAP WINDS REMAIN LIGHT. CROSS 
EQUATORIAL SLY WINDS DECREASE SOME E OF 100W BUT ARE FORECAST TO 
STRENGTHEN TO 20 TO 25 KT FROM 6N TO 12N BETWEEN 102W AND 112W 
WITH SLY SWELL TO 9 FT.

$$
RRG