000
AXPZ20 KNHC 210321
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC MON SEP 21 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.

...TROPICAL WAVE...

A TROPICAL WAVE LIES ALONG 102W FROM 08N TO 16N MOVING W 15 KT. 
SHORTWAVE IR IMAGES SHOW A BROAD AREA OF MID-LEVEL CYCLONIC 
TURNING ASSOCIATED WITH THIS WAVE. SCATTERED MODERATE CONVECTION 
IS MAINLY LOCATED WEST OF THE ANALYZED AXIS FROM 08N TO 15N 
BETWEEN 103W AND 113W.

...THE ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG A LINE FROM 07N77W 
TO 13N100W TO 10N112W TO 12N132W TO 10N140W. SCATTERED MODERATE 
TO STRONG CONVECTION IS N OF 07N E OF 80W. SCATTERED MODERATE 
CONVECTION IS FROM 08N TO 15N BETWEEN 103W AND 113W. SCATTERED 
MODERATE CONVECTION IS WITHIN 120 NM N OF AXIS W OF 131W. 

...DISCUSSION...

N OF 20N...
A COUPLE OF WEAK SURFACE LOWS ARE OVER THE DISCUSSION AREA. ONE 
IS THE REMNANTS OF MARTY CENTERED NEAR 23N124W MOVING W 10-15 
KT. THE OTHER IS A MUCH SMALLER SYSTEM LOCATED ABOUT 180 NM W OF 
THE SRN TIP OF BAJA CALIFORNIA NEAR 22N113W. BOTH OF THESE ARE 
ONLY LOW-LEVEL CLOUD SWIRLS...BUT STILL ARE PRODUCING A SMALL 
AREA OF 20 KT WINDS BASED ON SHIP AND SCATTEROMETER DATA. THE 
EASTERN LOW IS EXPECTED TO DISSIPATE LATER TONIGHT OR TOMORROW. 
THE REMNANTS OF MARTY WILL LIKELY BE SLOWER TO DISSIPATE BUT 
WINDS ARE EXPECTED TO DIMINISH BELOW 20 KT WITHIN THE NEXT 36 
HOURS OR SO. THE ONLY OTHER AREA OF 20 KT WINDS ARE OVER THE FAR 
NW CORNER OF THE DISCUSSION AREA...ASSOCIATED WITH THE PRESSURE 
GRADIENT BETWEEN THE REMNANTS OF MARTY AND HIGH PRESSURE WELL 
NORTH OF THE AREA. THIS AREA OF WIND WILL ALSO DIMINISH ON MON 
AS THE HIGH SHIFTS NORTHEASTWARD IN RESPONSE TO AN APPROACHING 
COLD FRONT. NW SWELL...ASSOCIATED WITH A STORM SYSTEM N OF 
HAWAII...WILL CONTINUE TO AFFECT THE REGION OVER THE NEXT FEW 
DAYS.

S OF 20N...
A LARGE MID TO UPPER LEVEL ANTICYCLONE IS SITUATED OVER SOUTHERN 
MEXICO AND A FLATTER RIDGE IS CENTERED NEAR 14N133W. NE TO E 
FLOW ALOFT ON THE SOUTHERN PERIPHERY OF THE ANTICYCLONE IS 
TRANSPORTING MOISTURE WESTWARD TO 115W. A WEAK SURFACE TROUGH IS 
NOTED ALONG 128W CAUSING A WEAK PERTURBATION IN THE ITCZ BUT 
LITTLE SIGNIFICANT CONVECTION. CONVECTION REMAINS CONFINED TO 
THE TROPICAL WAVE...ITCZ...AND NEAR THE COASTS OF EL SALVADOR... 
GUATEMALA AND SOUTHERN MEXICO WHERE UPPER LEVEL DIFFLUENCE AND 
LOCAL EFFECTS ARE THE PRIMARY FORCING MECHANISMS. 

SLY SWELL...WITH PERIODS IN THE 17-19 SECOND RANGE...IS 
AFFECTING THE CENTRAL AMERICA AND MEXICO COASTS E OF ABOUT 105W. 
CONDITIONS WILL SLOWLY SUBSIDE OVER THE NEXT COUPLE OF DAYS.

$$
CANGIALOSI