000
AXPZ20 KNHC 291521
TWDEP 

TROPICAL WEATHER DISCUSSION     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE AUG 28 2007

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...SPECIAL FEATURES...

SATELLITE IMAGES INDICATE THAT THE AREA OF LOW PRESSURE SOUTH OF 
BAJA CALIFORNIA HAS BECOME BETTER ORGANIZED WITH IMPRESSIVE 
CURVED BANDING FEATURES ESPECIALLY IN THE SOUTHERN SEMICIRCLE. 
AT 29/1500 UTC THIS SYSTEM IS UPGRADED TO A TROPICAL DEPRESSION 
WITH MAXIMUM SUSTAINED WINDS OF 30 KT. ESTIMATED MINIMUM 
PRESSURE IS 1000 MB AND IS MOVING WEST-NORTHWEST AT 8 KT. 
ALTHOUGH THE ENVIRONMENT IS ONLY MARGINALLY FAVORABLE FOR FURTHER
STRENGTHENING WITH MODERATE EASTERLY SHEAR...THE SYSTEM IS 
FORECAST TO BRIEFLY REACH TROPICAL STORM STRENGTH BEFORE REACHES 
COOLER WATERS. SCATTERED MODERATE TO STRONG CONVECTION IS  
WITHIN 60 NM OF 18N110W. SCATTERED MODERATE ISOLATED STRONG IS
WITHIN 120 NM OF MEXICAN COAST FROM 102W TO 106W.

A 1008 MB LOW CENTERED ALONG THE ITCZ NEAR 12N95W IS MOVING W AT 
10 KT. CONVECTION REMAINS WEAK AND DISORGANIZED AROUND THIS LOW 
SO FAR. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NOTED 
WITHIN 75 NM N OF THE CENTER AND WELL TO THE NW...WITHIN 300 NM  
OF THE CENTER. SOME SLOW DEVELOPMENT OF THIS SYSTEM IS POSSIBLE 
DURING THE NEXT COUPLE OF DAYS AS IT MOVES WESTWARD AT 10 TO 15 
MPH. 

...TROPICAL WAVE...

A TROPICAL WAVE EXTENDS ALONG 88W N OF 6N TO ACROSS BELIZE AND 
THE YUCATAN PENINSULA...MOVING W AT 10 TO 15 KT. THE WAVE 
REMAINS POORLY DEFINED OVER PACIFIC WATERS DUE TO PREDOMINANCE 
OF SWLY SURFACE FLOW IN THE AREA...AS DEPICTED IN SHIP 
OBSERVATIONS AND EARLIER QUIKSCAT PASS. THE WAVE IS HELPING TO 
INDUCE MODERATE CONVECTION OVER BELIZE AND THE NW CARIBBEAN... 
BUT LITTLE SIGNIFICANT CONVECTION IS NOTED WITH THIS FEATURE 
OVER PACIFIC WATERS.

...ITCZ...

INTERTROPICAL CONVERGENCE ZONE...13N87W 13N96W 13N120W 16N133W 
12N140W. SCATTERED MODERATE ISOLATED STRONG WITHIN 30 NM 8N85W 
AND WITHIN 120 NM EITHER SIDE OF LINE 9N96W 14N111W AND WITHIN 
60 NM 9N125W. 

...DISCUSSION...

E OF 120W...LIGHT TO MODERATE S TO SW FLOW PERSISTS S OF THE 
ITCZ ACCOMPANIED BY GENERALLY 12S PERIOD SWELL OF UP TO 8 FT. . 
STRONGER SURFACE WINDS ARE NOTED ON SCATTEROMETER IMAGERY ON THE 
S SIDE OF THE DEVELOPING LOW NEAR 12N95W. SEAS MAY BUILD ALONG 
THE MEXICAN COAST OVER THE NEXT 48 HOURS AS WELL DUE TO A 
COMBINATION OF SLY SWELL ALONG WITH INCREASED WINDS AROUND THE 
DEVELOPING LOW NOW NEAR 12N95W. ALOFT...GENERALLY NE TO E FLOW 
CONTINUES OVER THE AREA...BETWEEN AN INVERTED TROUGH OVER THE 
CENTRAL GULF OF MEXICO AND A BROAD UPPER ANTICYCLONE OVER NRN 
MEXICO. DIVERGENCE ALOFT AT THE BASE OF THE BROAD ANTICYCLONE 
OVER NRN MEXICO IS SUPPORTING A BAND OF SCATTERED MODERATE TO 
ISOLATED STRONG CONVECTION OVER THE MEXICAN COAST FROM 
MANZANILLO TO MAZATLAN.

W OF 120W...
DRY/STABLE AIR ALOFT DOMINATES MUCH OF THE AREA W OF 120W EXCEPT 
ALONG THE IMMEDIATE ITCZ. A WEAK TROUGH IS IN THE AREA FROM 
16N131W TO 11N137W. 1024 MB HIGH PRES REMAINS CENTERED NW OF THE 
AREA. BROKEN TO OVERCAST LOW/MID CLOUDS AND MODERATE NELY FLOW 
ARE NOTED UNDER THE INFLUENCE OF THIS HIGH. N OF THE ITCZ 
BETWEEN THE HIGH AND LOW PRES SYSTEMS SEA HEIGHTS ARE GENERALLY 
BELOW 8 FT. S OF THE ITCZ...LIGHT TO MODERATE SLY FLOW CONTINUES 
WITH UP TO 8 FT SWELL NOTED. 

$$
GR