000
AXPZ20 KNHC 120906
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT SEP 12 2009

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.

...TROPICAL WAVES...

TROPICAL WAVE NORTH OF 05N ALONG 85W MOVE W 15 KT. SCATTERED 
MODERATE WITH ISOLATED STRONG CONVECTION IS WITHIN 60 NM OF 
06N84W WITHIN THE ITCZ. THERE IS SOME SLIGHT ORGANIZATION TO THE 
CONVECTION. DEVELOPMENT IS NOT FORECAST BY THE COMPUTER MODELS.

TROPICAL WAVE FROM 04N TO 17N ALONG 105W MOVE WEST 15 KT. 
ISOLATED CONVECTION WITHIN THE ITCZ IS NEAR THE WAVE AXIS BUT IT 
SHOWS NO ORGANIZATION. 

...THE ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE 06N77W TO 
08N105W TO 05N140W. SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION IS WITHIN THE AREA 75 NM EITHER SIDE OF THE ITCZ AXIS 
EAST OF 80W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION 
IS WITHIN 60 NM OF THE POINT 06N84W. SCATTERED MODERATE WITH 
ISOLATED STRONG CONVECTION IS WITHIN 90 NM OF THE POINT 11N94.5W.

...DISCUSSION...

DEEP LAYER TROUGH IS NORTHWEST OF A LINE THROUGH 32N118W TO 
10N140W. THE AREA IS DRY AND CLOUD FREE IN THE MIDDLE AND UPPER 
LEVELS. BROKEN TO OVERCAST LOW CLOUDS ARE WITHIN 240 NM OF THE 
NORTHWEST SEMICIRCLE OF THE REMNANT OF LINDA AND WITHIN 120 NM 
OF THE SOUTHEAST SEMICIRCLE. OTHERWISE BROKEN STRATOCUMULUS IS 
NORTHWEST OF A LINE FROM 32N117W TO 20N140W. THE REMNANT LOW OF 
LINDA IS FORECAST TO MOVE WEST NORTHWEST SLOWLY AND WEAKEN 
BECOMING DIFFUSE IN 48 HOURS. 

ANOTHER TROUGH IS OVER MEXICO EAST OF THE LINE FROM 32N110W TO 
20N105W AND WEST OF THE MOUTH OF THE RIO GRANDE TO 20N100W TO 
20N105W. CONVECTION IS OCCURRING AT THE BASE OF THE TROUGH ALONG 
THE WEST COAST OF MEXICO WITH SCATTERED MODERATE WITH ISOLATED 
STRONG WITHIN 60 NM OF THE POINT 22N105W. ALSO CONVECTION IS 
JUST EAST OF THE TROUGH OVER THE WESTERN GULF OF MEXICO.

A BROAD TROUGH IS OVER THE PACIFIC OCEAN NORTH OF THE ITCZ EAST 
OF 100W. THIS AREA IS MOIST ALOFT WITH MULTI LEVEL BROKEN TO 
OVERCAST CLOUDS. SEVERAL AREAS OF CONVECTION ARE EMBEDDED WITHIN 
THIS AREA.

OTHERWISE A LARGE ANTICYCLONIC FLOW COVERS THE AREA. MOST OF 
THIS AREA IS DRY AND CLOUD FREE IN THE MIDDLE AND UPPER LEVELS. 
AN EXCEPTION IS NEAR THE SOUTHEAST PART OF THE RIDGE FROM 10N TO 
15N EAST OF 122W WHERE MOISTURE FROM THE TROUGH EAST OF THE 
RIDGE IS ADVECTING WESTWARD NORTH OF THE ITCZ. 

A TIGHT PRESSURE GRADIENT CONTINUES BETWEEN THE LOW THAT IS THE 
REMNANT OF LINDA AND RIDGING TO ITS NW. THIS IS MAINTAINING THE 
STRONGEST WINDS WITH LINDA OF 20-30 KT IN THE NW SEMICIRCLE. 
WINDS WILL GRADUALLY SUBSIDE THROUGH THE NEXT 48 HOURS AS THE 
LOW WEAKENS FURTHER.

A DEEP LAYER TROUGH NW OF THE REGION MOVING RAPIDLY SE TOWARDS 
THE FAR NW CORNER IS CONSISTENTLY BEING FORECAST BY NWP MODELS 
TO PUSH A COLD FRONT NEAR THE NW PORTION OF THE AREA DURING THE 
WEEKEND BRINGING LARGE LONG PERIOD NWLY SWELLS MAXING UP TO 10 
OF 11 FT PER LATEST WAVE MODEL GUIDANCE. THESE SWELLS SHOULD 
OVERSPREAD ACROSS THE NW PART OF THE AREA THROUGH THE WEEKEND AS 
THE FRONT WEAKENS OVER THE FAR NORTHERN SECTION.

CROSS EQUATORIAL SLY WINDS OF 20 KT AND SWELLS GENERATED BY A 
BROAD FIELD OF SE WINDS 20-30 KT S OF THE EQUATOR WILL CONTINUE 
TO AFFECT THE FAR SOUTHERN PORTION S OF 07N BETWEEN 92W-118W.

$$
LL