000
AXPZ20 KNHC 171512
TWDEP 

TROPICAL WEATHER DISCUSSION      
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON SEP 17 2007

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...SPECIAL FEATURES...

AN AREA OF LOW PRES...ASSOCIATED WITH A TROPICAL WAVE...IS 
ANALYZED 1008 MB CENTERED NEAR 12N103W...OR ABOUT 500 NM SSW OF 
ACAPULCO MEXICO. SCATTERED SHOWERS AND TSTMS ARE MOSTLY ALIGNED 
NE-SW TO THE N AND W OF THE LOW-LEVEL CENTER FROM 12N-16N 
BETWEEN 100W-105W. A QSCAT PASS AROUND 12Z PARTIALLY CAPTURED 
THE CIRCULATION OF THIS SYSTEM. IT REVEALED SEVERAL 
UNCONTAMINATED 20 KT VECTORS TO THE E OF THE LOW. CONDITIONS 
APPEAR FAVORABLE FOR DEVELOPMENT...AND A TROPICAL DEPRESSION 
COULD FORM DURING THE NEXT COUPLE OF DAYS AS IT MOVES WESTWARD 
OR WEST-NORTHWESTWARD AT 10 KT.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 114W FROM 7N TO 18N IS MOVING WWD AROUND 5 
KT. A WEAK 1009 MB LOW IS ALONG THE WAVE AXIS NEAR 16N. THE LOW 
IS RATHER SMALL AND VOID OF ANY DEEP CONVECTION FOR THE TIME 
BEING. ONLY ISOLATED TO SCATTERED SHOWERS AND TSTMS ARE WITHIN 
120 NM W TO NW OF THE LOW...AND ALONG THE WAVE AXIS N OF 13N 
SHEARED BY MODERATE NE TO ELY FLOW. STRONGER MORE ORGANIZED 
CONVECTION IS W OF THE WAVE ALIGNED WITHIN THE ITCZ.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 9N84W 7N85W 16N111W 10N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS WITHIN 120 NM N 
OF OF AXIS FROM 117W TO 124W. SCATTERED STRONG IS WITHIN 110 NM 
N OF AXIS FROM 127W TO 130W.

...DISCUSSION...
AT THE SFC...MODERATE SUBTROPICAL RIDGING IS IN PLACE EXTENDING 
SW FROM A 1029 MB HIGH CENTER LOCATED WELL NW OF THE AREA NEAR 
36N148W. IN ADDITION TO THE TROPICAL WAVES DISCUSSED ABOVE THERE 
IS ANOTHER AREA OF LOW PRES ALONG THE ITCZ. THIS SYSTEM IS 
CENTERED NEAR 14N126W ANALYZED 1009 MB. THE LOW-LEVEL CLOUD 
STRUCTURE IS ILL-DEFINED THOUGH THERE ARE SOME STREAMERS 
SUGGESTING THAT IT IS STILL CLOSED. ASSOCIATED CONVECTION IS 
ORGANIZED LINEARLY WITHIN THE ITCZ. THE TIGHTENED PRES GRADIENT 
BETWEEN THE SUBTROPICAL HIGH AND LOWS ALONG THE ITCZ IS 
ENHANCING NE TRADES ACROSS THE W PORTION OF THE REGION. 

IN THE MID AND UPPER LEVELS...AN UPPER LOW IS DRIFTING NW 
CENTERED NEAR OUR NW CORNER NEAR 29N139W. A SHARP SHORTWAVE 
TROUGH EXTENDS SWD FROM THE WRN U.S. ACROSS NW MEXICO. THE 
REMAINDER OF THE REGION W OF 110W IS DOMINATED BY A MID TO UPPER 
HIGH CENTERED NEAR 22N120W. THIS HIGH IS RESPONSIBLE FOR 
PROVIDING THE NE/ELY SHEAR OVER THE TROPICAL WAVE ALONG 114W. 
BESIDES FOR THE MOISTURE PLUME ACROSS THE TROPICAL BELT S OF 
19N...PRODUCED MOSTLY BY THE TROPICAL WAVES AND THE ITCZ...DRY 
STABLE AIR DOMINATES THE REMAINDER OF THE REGION W OF 110W 
ENHANCED BY A SOMEWHAT CONFLUENT PATTERN.

THE FLOW ACROSS THE TROPICAL EPAC E OF 110W IS PRIMARILY ELY 
THOUGH IT IS PERTURBED BY AN UPPER LOW LOCATED OVER SW MEXICO 
NEAR 20N97W. BESIDES FOR THE SPECIAL FEATURE...THERE IS NOT MUCH 
SENSIBLE WEATHER IN THIS AREA.

$$
CANGIALOSI