000
AXPZ20 KNHC 212148
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON SEP 21 2009

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2130 UTC.

...SPECIAL FEATURE...

AN AREA OF LOW PRESSURE 1010 MB HAS DEVELOPED NEAR 13N113W ALONG 
A SURFACE TROUGH EXTENDING FROM 09N113W TO 18N110W. VISIBLE 
SATELLITE IMAGERY INDICATED INCREASING CYCLONIC TURNING IN THE 
LOW LEVELS. IN ADDITION CLUSTERS OF SCATTERED MODERATE TO STRONG 
CONVECTION APPEARED TO ROTATE CYCLONICALLY AS WELL. THE AREA OF 
LOW PRESSURE IS SITUATED WITHIN AN AREA OF DIFFLUENT FLOW ALOFT 
TO THE SW OF AN UPPER LEVEL ANTICYCLONE OVER MEXICO. THERE IS A 
MODERATE PROBABILITY OF TROPICAL CYCLONE FORMATION WITH THIS 
AREA OF LOW PRESSURE OVER THE NEXT 48 HOURS. 

...THE ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG A LINE FROM 07N78W 
TO 08N96W TO 15N101W TO 12N115W TO 10N140W. SCATTERED MODERATE 
TO STRONG WITHIN 150 NM OF AXIS E OF 85W. SCATTERED MODERATE 
FROM 05N TO 08N BETWEEN 125W AND 130W. SCATTERED MODERATE 
ISOLATED STRONG FROM 12N TO 14N BETWEEN 133W AND 136W.

...DISCUSSION...

N OF 20N...
TWO WEAK SURFACE LOWS REMAIN OVER THE DISCUSSION AREA. THE 
WESTERN LOW IS A 1014 MB REMNANT LOW OF MARTY CENTERED NEAR 
23N127W MOVING W 10 KT. THE OTHER LOW IS A SMALLER CIRCULATION 
LOCATED ABOUT 240 NM WSW OF THE SRN TIP OF BAJA CALIFORNIA NEAR 
23N114W MOVING NW AT 5 KT. NEITHER LOW HAS ASSOCIATED DEEP 
CONVECTION. A 1418 UTC QUIKSCAT PASS INDICATED THAT THE REMNANT 
LOW OF MARTY WAS SLOWLY SPINNING DOWN WITH THE QUIKSCAT PASS NOW 
SHOWING 20 KT WINDS WITHIN 150-180 NM IN THE NW QUADRANT. THE 
REMNANTS OF MARTY SHOULD WEAKEN TO A TROUGH WITHIN THE NEXT 18 
TO 24 HOURS WITH WINDS DIMINISHING AND SEAS SUBSIDING AS IT 
ENCOUNTERS INCREASINGLY MORE HOSTILE CONDITIONS. A SHARPENING 
DEEP LAYER TROUGH WELL TO THE NW OF THE AREA IS EXPECTED TO 
PROGRESS SLOWLY EASTWARD OVER THE NEXT SEVERAL DAYS. THE 
ASSOCIATED SURFACE COLD FRONT IS WELL NW OF THE AREA AND IS NOT 
EXPECTED TO ENTER THE FORECAST WATERS AND SHOULD DISSIPATE BY 
WED. ONE OTHER NOTE...WINDS IN THE GULF OF CALIFORNIA MAY 
BRIEFLY REACH 20 KT WITH A COLD FRONTAL PASSAGE OVERNIGHT TUE 
NIGHT. THIS EVENT IS EXPECTED TO BE SHORT-LIVED AND THE 
NUMERICAL MODELS HAVE TRENDED TOWARD A WEAKER WIND EVENT THE 
PAST FEW RUNS. 

S OF 20N...
DIFFLUENCE ALOFT BETWEEN AN ANTICYCLONE CENTERED OVER COLOMBIA 
NEAR 07N76W AND A LARGE UPPER LOW JUST TO THE SOUTH OF THE 
EQUATOR ALONG 101W IS PROVIDING LIFT TO THE LOW LEVEL MOISTURE 
POOLED ALONG THE ITCZ OVER FAR EASTERN WATERS. CLUSTERS OF 
SCATTERED STRONG CONVECTION CONTINUE S OF THE ITCZ WITHIN 
180-240 NM OF THE COAST OF PANAMA AND COSTA RICA. SOUTHERLY 
SWELL...WITH PERIODS IN THE 16 SECOND RANGE...CAN BE FOUND 
ALONG THE CENTRAL AMERICA AND SOUTHERN MEXICO COASTS E OF 100W. 
CONDITIONS WILL SLOWLY SUBSIDE OVER THE NEXT COUPLE OF DAYS. 
ELSEWHERE ASIDE FROM THE PREVIOUSLY MENTIONED SYSTEMS...A WEAK 
SURFACE TROUGH IS FOUND ALONG 129W FROM 10N TO 16N CAUSING A 
WEAK PERTURBATION IN THE ITCZ BUT LIMITED CONVECTION. 

$$
COBB