000
AXPZ20 KNHC 122204
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED SEP 12 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2115 UTC.

...SPECIAL FEATURE...
NEWLY UPGRADED TROPICAL STORM KRISTY WAS CENTERED NEAR 18.2N
106.9W 1005 MB AT 2100 UTC MOVING NW AT 9 KT WITH MAXIMUM 
SUSTAINED WINDS 40 KT GUSTS 50 KT AND MINIMUM PRESSURE 1005 MB. 
KRISTY IS EXHIBITING TIGHT BANDING WRAPPING INTO THE CENTER MOST
NOTICEABLY IN THE SE SEMICIRCLE. SCATTERED STRONG CONVECTION IS
WITHIN 60 NM OF THE CENTER IN THE SE QUADRANT. SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION IS ELSEWHERE WITHIN 270 NM 
OF THE CENTER IN THE E SEMICIRCLE...AND ALSO FROM 10N TO 14N 
BETWEEN 107W-109W. SCATTERED MODERATE CONVECTION IS WITHIN 120 
NM OF THE CENTER IN THE W SEMICIRCLE. KRISTY IS FORECAST TO 
SLOWLY INTENSIFY AS IT MOVES NW OVER THE NEXT 36 HOURS...THEN 
BEGIN TO WEAKEN BETWEEN 36 AND 48 HRS AS IT MOVES OVER COOLER 
WATERS. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM 09N85W TO 07N95W TO 12N108W 
WHERE IT ENDS. IT RESUMES TO THE SW OF KRISTY AT 16N112W TO 
14N120W WHERE LOW LEVEL WINDS SUGGEST THE ITCZ BEGINS AND 
CONTINUES TO 14N126W TO 09N134W TO 08N140W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS WITHIN 120 NM S OF THE ITCZ W OF 
135W. SCATTERED STRONG CONVECTION IS NOTED SE OF THE TROUGH FROM 
04N TO 07N E OF 84W.

...DISCUSSION...

THE AREA IS UNDER SUBSIDENCE ALOFT WITH DRY AND STABLE CONDITIONS
...WITH THE EXCEPTION OF THE SE AND FAR S AND SW PORTIONS WHERE
VERY DEEP MOISTURE THROUGH THE ATMOSPHERE IS NOTED ESPECIALLY 
OVER AND NEAR TROPICAL STORM KRISTY. A HIGH PRES SYSTEM LOCATED 
N OF THE AREA AT 43N138W EXTENDS A RIDGE SEWD THROUGH 32N130W TO 
27N118W. LIGHT TO MODERATE WINDS PREVAIL OVER MOST OF THE 
REGION...EXCEPT ALONG THE SOUTHERN COAST OF MEXICO IN THE 
VICINITY OF TROPICAL STORM KRISTY...AND WITHIN 300 NM N OF THE 
ITCZ W OF ABOUT 131W IN ENHANCED NE TRADE WIND FLOW AS REVEALED 
BY AN ASCAT PASS FROM 1526 UTC. SIMILAR WINDS ARE ALSO FOUND 
JUST W OF THE GULF OF PAPAGAYO IN FRESH TO STRONG E-NE GAP WINDS 
FUNNELING FROM THE WESTERN CARIBBEAN THROUGH CENTRAL AMERICA
...BUILDING SEAS IN THE GULF OF PAPAGAYO TO AROUND 8 FT. THESE
WINDS ARE FORECAST TO DIMINISH TO 20 KT OR LESS WITH SEAS LESS
THAN 8 FT ON THU.

FRESH NE WINDS WITH SEAS AROUND 7 FT ARE EXPECTED TO PERSIST N 
OF THE CONVERGENCE ZONE W OF 130W THROUGH FRI. WINDS AND SEAS 
ARE EXPECTED TO DIMINISH DOWNSTREAM OF THE GULF OF PAPAGAYO LATE 
TONIGHT AND THU...THEN INCREASE AGAIN FRI MORNING. N-NE WINDS
OF 20-25 KT THROUGH THE GULF OF TEHUANTEPEC ARE FORECAST TO
DIMINISH TO 20 KT OR LESS IN ABOUT 19 HOURS...BUT INCREASE
AGAIN TO 20-30 KT ON FRI WITH SEAS BUILDING TO 8 FT.

LOOKING FURTHER AHEAD...THE GFS MODEL SPINS UP A STRONG LOW PRES 
SYSTEM AT THE WESTERN END OF THE MONSOON TROUGH NEAR 13N130W BY 
FRI WHICH MOVES NORTHWARD THROUGH THE WEEKEND. HOWEVER THE ECMWF 
AND UKMET MODELS SHOW LITTLE CHANCE FOR CYCLOGENESIS IN THIS AREA
AND MOVE THE DISTURBANCE WNW IN THE TRADE WIND FLOW. CONSEQUENTLY
HAVE HEDGED TOWARD EUROPEAN SOLUTION IN LONG TERM FORECAST GRIDS.

$$
AGUIRRE