000
AXPZ20 KNHC 160328
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED SEP 16 2009

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...SPECIAL FEATURE...

A SURFACE LOW LIES NEAR 18N112W 1007 MB MOVING W-NW 5-10 KT.  
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION CAN BE FOUND 
WITHIN 120 NM W SEMICIRCLE. AN EARLIER QUIKSCAT PASS SHOWED THAT 
THE LOW IS ELONGATED NE TO SW WITH SW FLOW AT 20 TO 25 KT 
FEEDING TROPICAL MOISTURE INTO THE SYSTEM. CONDITIONS WILL 
REMAIN FAVORABLE FOR FURTHER DEVELOPMENT...AND IT COULD DEVELOP 
INTO A TROPICAL CYCLONE BEFORE REACHING COOLER WATERS IN A 
COUPLE OF DAYS.  

...TROPICAL WAVE...

TROPICAL WAVE ALONG 123W FROM 06N TO 16N MOVING WEST AROUND 10 
KT. THERE IS NO SIGNIFICANT DEEP CONVECTION ASSOCIATED WITH THE 
WAVE AT THIS TIME. ISOLATED MODERATE CONVECTION IS WHERE THE 
WAVE AXIS MEETS THE ITCZ. 

...THE ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG 07N78W TO 06N90W TO 
10N102W...THEN CONTINUING ALONG 11N124 TO 09N135W TO 07N140W. 
ISOLATED TO SCATTERED MODERATE CONVECTION IS WITHIN 100 NM 
EITHER SIDE OF AXIS E OF 95W. SCATTERED MODERATE TO ISOLATED 
STRONG CONVECTION IS NOTED FROM 07N TO 10N W OF 130W. 

...DISCUSSION...

N OF 20N...A SURFACE RIDGE...ANCHORED ON A 1020 MB HIGH PRES 
NEAR 29N128W CONTINUES TO BUILD SOUTHWARD OVER N WATERS. THE 
REGION IS MARKED BY MODERATE TO STRONG SUBSIDENCE WITH BROKEN 
STRATOCUMULUS CLOUDS COVERING THE AREA E OF 130W. PRES GRADIENT 
BETWEEN THIS RIDGE AND A SFC TROUGH OVER WESTERN MEXICO IS 
PRODUCING NW WINDS OF 20 KT AND SEAS TO 8 FT N OF 25N AND WITHIN 
120 NM OF THE BAJA CALIFORNIA PENINSULA. VIS SATELLITE IMAGERY 
IS STILL SHOWING A SWIRL OF LOW CLOUDS NEAR 22N140W ASSOCIATED 
WITH THE REMNANTS OF LINDA WHICH HAVE BEEN DEGRADED TO A SURFACE 
TROUGH FROM 26N138W TO 22N140W. AN EARLIER QSCAT SHOWED THE WIND 
SHIFT ASSOCIATED WITH THE TROUGH. WINDS HAVE DIMINISHED BELOW 20 
KT WITH THIS FEATURE. THE LEADING EDGE OF A COLD FRONT IS 
APPROACHING THE FAR NW CORNER OF THE AREA. A DEEP-LAYER TROUGH 
SUPPORTS THIS FRONTAL SYSTEM. THE FRONT WILL MOVE INTO NW WATERS 
OVERNIGHT AND IS EXPECTED TO DISSIPATE BY THU MORNING. 
SIGNIFICANT WAVE HEIGHTS WILL BUILD INTO THE 8 TO 10 FT RANGE IN 
NW SWELL WED AND THU OVER NW WATERS.

S OF 20N...ASIDE FROM THE AFOREMENTIONED SPECIAL FEATURE...THE 
TROPICAL WAVE...AND THE CONVECTION ALONG THE ITCZ...CONDITIONS 
ARE RELATIVELY QUIET OVER THE REMAINDER OF THE AREA. A DIFFLUENT 
PATTERN ALOFT ASSOCIATED WITH AN UPPER-LEVEL ANTICYCLONE 
CENTERED OVER WESTERN CUBA IS HELPING TO INDUCE CONVECTION OVER 
THE FAR EPAC WATERS AND ALONG THE ITCZ PARTICULARLY E OF 95W. 
ANOTHER SURFACE TROUGH IS ANALYZED FROM 12N137W TO 06N138W. AN 
ASCAT PASS FROM AROUND 1900 UTC REVEALED THE PRESENCE OF THIS 
FEATURE. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS 
NOTED NEAR THE INTERSECTION OF THE TROUGH AND THE ITCZ AXIS.

$$
GR/JSC