000
AXPZ20 KNHC 130906
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN SEP 13 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 ALONG 91W/92W NORTH OF 05N MOVE WEST 15 KT. NO 
CONVECTION IS NOTED NEAR THE WAVE.

TROPICAL WAVE ALONG 110W/111W FROM 05N TO 17N MOVE WEST 15 KT. 
CONVECTION IS EAST OF THE WAVE AXIS WITHIN THE ITCZ AND IS 
DESCRIBED IN THE ITCZ SECTION. NO ORGANIZATION OF THE CONVECTION 
IS NOTED. 

...THE ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE 06N77W TO 
10N95W TO 10N105W TO 05N140W. SCATTERED MODERATE WITH ISOLATED 
STRONG CONVECTION IS WITHIN THE AREA FROM 09.5N TO 12N FROM 95W 
TO 101W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 75 NM 
EITHER SIDE OF A LINE FROM 14N105W TO 10N108W TO 08N114W. 
SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 100 NM OF THE 
POINT 06.5N128W.

...DISCUSSION...

DEEP LAYER TROUGH IS OVER THE NORTHWEST PART OF THE AREA 
NORTHWEST OF A LINE FROM SOUTHERN CALIFORNIA TO 20N140W. THE 
AREA IS DRY AND CLOUD FREE IN THE MIDDLE AND UPPER LEVELS WITH 
BROKEN TO OVERCAST STRATOCUMULUS IN THE LOWER LEVELS. A WEAK 
COLD FRONT IS OVER THE FAR NORTHWEST PART OF THE AREA. THE 
TROUGH IS FORECAST TO MOVE EAST AND BE REPLACED BY NEAR ZONAL 
FLOW IN THE NEXT DAY OR TWO. THE COLD FRONT IS FORECAST TO 
WEAKEN AS IT MOVES EAST BECOMING DIFFUSE SOUTH OF 32N MONDAY.

ANOTHER DEEP LAYER TROUGH EXTENDS SOUTH FROM A CYCLONIC 
CIRCULATION THAT IS OVER TEXAS. THE TROUGH IS EAST OF A LINE 
THAT EXTENDS FROM SOUTHEASTERN ARIZONA TO THE ITCZ NEAR 100W AND 
WEST OF A LINE THAT EXTENDS FROM SOUTHEASTERN LOUISIANA TO THE 
ITCZ NEAR 95W. THERE IS SOME CONVECTION IN THE ITCZ NEAR THE 
BASE OF THE TROUGH BUT OTHERWISE CONVECTION IS ISOLATED OVER THE 
WESTERN GULF OF MEXICO. SOME CONVECTION WAS OVER THE SIERRA 
MADRE OCCIDENTAL DURING THE DAYTIME BUT THIS CONVECTION HAS 
DIMINISHED TONIGHT. RECURRENCE DURING THE DAY TODAY IS 
LIKELY.

BETWEEN THE TWO ABOVE TROUGHS A LARGE BROAD ANTICYCLONIC 
CIRCULATION DOMINATES THE FLOW. THE FLOW IS DIFFLUENT ALOFT 
ALONG THE SOUTHEASTERN PART OF THE FLOW WITH A LARGE AREA OF 
CONVECTION THAT IS MENTIONED IN THE ITCZ SECTION.

DIFFLUENT FLOW ALOFT IS NOTED EAST OF 90W WITH MULTI LEVEL 
CLOUDS AND SOME EMBEDDED CONVECTION.

A FLAT PRESSURE GRADIENT IS OBSERVED AT THE SURFACE WITH A WEAK 
RIDGE BETWEEN THE LOW THAT IS THE REMNANT OF LINDA NEAR 21N133W 
AND THE COLD FRONT OVER THE FAR NORTHWEST PART.

$$
LL