000
AXPZ20 KNHC 110921
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE SEP 11 2012

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...SPECIAL FEATURE...
BROAD AREA OF LOW PRESSURE NEAR 13N100W IS MOVING W-NW AROUND 10 
KT. EASTERLY WINDS TO 25 KT ARE WITHIN 210 NM OF THE CENTER OVER 
THE N AND NE QUADRANTS. NUMEROUS MODERATE TO STRONG CONVECTION 
WAS WITHIN 240 NM N SEMICIRCLE OF THE LOW PRES INCLUDING ALONG 
THE COAST OF SOUTHERN MEXICO. ENVIRONMENTAL CONDITIONS REMAIN 
CONDUCIVE FOR THE FORMATION OF A TROPICAL CYCLONE OVER THE 
NEXT COUPLE OF DAYS. THIS LOW PRES SYSTEM IS CURRENTLY FORECAST 
TO GRADUALLY DEEPEN AND WINDS INCREASE TO 30 KT AS IT CONTINUES 
NORTHWESTWARD THROUGH WED EVENING.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH FROM 10N86W TO 9N90W TO LOW PRES NEAR 13N100W TO 
13N110W 10N130W 8N140W. NUMEROUS MODERATE TO STRONG CONVECTION 
WITHIN 240 NM N OF AXIS FROM 98W-103W. SCATTERED MODERATE TO 
STRONG CONVECTION WITHIN 120 NM N OF AXIS FROM 102W-116W AND 
WITHIN 120 NM S OF AXIS FROM 122W-136W.

...DISCUSSION...
UPPER LEVEL RIDGE EXTENDS FROM AND ANTICYCLONIC CIRCULATION 
CENTERED NEAR 23N126W N TO 32N126W. STRONG SUBSIDENCE WITH DRY 
AND STABLE AIR AT THE MIDDLE AND UPPER LEVELS IS N OF 15N W OF 
115W. UPPER LEVEL TROUGH ALONG THE COASTS OF SOUTHERN CALIFORNIA 
AND BAJA CALIFORNIA FROM 32N117W TO 22N120W. DEEP LAYER MOISTURE 
REMAINS E OF THE TROUGH BUT HAS SHIFTED SLIGHTLY TO THE E ACROSS 
NW MEXICO INTO THE SW UNITED STATES. A LARGE UPPER LEVEL 
ANTICYCLONIC CIRCULATION IS CENTERED NEAR 18N103W WITH RIDGE 
EXTENDING NORTHWARD ACROSS MEXICO TO THE BIG BED OF TEXAS. 
SLIGHTLY DIFFLUENT FLOW ALOFT IS KEEPING ACTIVE CONVECTION 
ACROSS MUCH OF THE MONSOON TROUGH.

SURFACE RIDGE ACROSS THE AREA N OF 15N W OF 118W. ELY TRADES AT 
20 KT ALONG THE SOUTHERN PERIPHERY OF THE RIDGE FROM 13N-17N W 
OF 135W WILL DECREASE TO LESS THEN 20 KT LATER TODAY.

$$
DGS