000
AXPZ20 KNHC 191518
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON DEC 19 2011

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH FROM 8N83W 7N90W. ITCZ FROM 7N90W 6N100W 9N125W 
8N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 90 
NM N AND 60 NM S OF AXIS FROM 103W-108W.

...DISCUSSION...
A BROAD UPPER LEVEL RIDGE COVERS MOST OF THE AREA. THE RIDGE 
AXIS EXTENDS FROM AN ANTICYCLONIC CIRCULATION CENTERED NEAR
11N113W TO 30N140W. UPPER LEVEL DIFFLUENT FLOW S OF THE 
ANTICYCLONIC CIRCULATION IS ENHANCING CONVECTION ALONG THE ITCZ 
FROM 103W-108W. A 120-145 KT JETSTREAM ALONG THE NORTHERN 
PERIPHERY OF THE RIDGE...BETWEEN THE RIDGE AND AN UPPER LEVEL 
TROUGH N OF THE DISCUSSION AREA EXTENDS FROM 31N139W 30N120W
TO NORTHERN MEXICO NEAR 25N107W. HIGH LEVEL MOISTURE IS MOVING
THROUGH THE NORTHERN PORTION OF THE RIDGE N OF 29N W OF 115W.
UPPER LEVEL TROUGH EXTENDS FROM A CYCLONIC CIRCULATION OVER NEW 
MEXICO S ACROSS CENTRAL MEXICO TO 20N100W, MODERATE TO STRONG 
SUBSIDENCE WITH DRY STABLE AIR AT THE MIDDLE AND UPPER LEVELS IS 
N OF 12N E OF 115W.

SURFACE RIDGE COVERS THE ATLC N OF 18N W OF 110W. ELY WIND TO 20 
KT ARE ALONG THE SOUTHERN PORTION OF THE RIDGE FROM 9N-20N W OF 
115W WITH LARGE NW SWELLS...TO 11 FT...PROPAGATING THROUGH THE 
AREA N OF 10N W OF 113W. TIGHT PRES GRADIENT ACROSS SOUTHERN 
MEXICO IS PRODUCING 20-30 KT NLY WINDS THROUGH THE GULF OF 
TEHUANTEPEC. THE GRADIENT IS FORECAST TO RELAX AND WINDS SHOULD 
DECREASE TO BELOW 20 KT EARLY TUE.

$$
DGS