000
AXPZ20 KNHC 160845
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU SEP 15 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0830 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM 11N86W TO LOW PRES NEAR 
13N102W 1010 MB TO 11N120W TO LOW PRES NEAR 12N128W 1012 MB TO 
10N140W. SCATTERED MODERATE CONVECTION IS NOTED FROM 06N TO 12N 
BETWEEN 90W AND 95W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION IS NOTED WITHIN 120 NM S OF AXIS BETWEEN 110W AND 
115W. SCATTERED MODERATE CONVECTION IS NOTED FROM 08N TO 10N 
BETWEEN 125W AND 135W...AND WITHIN 60 NM EITHER SIDE OF AXIS W 
OF 135W.

...DISCUSSION... 

W OF 115W...AN UPPER TROUGH EXTENDING FROM THE NW UNITED 
STATES TO OFF THE COAST OF NORTHERN BAJA WILL LIFT N ACROSS THE 
NORTHERN ROCKIES THROUGH TODAY...AHEAD OF A VERY BROAD DEEP 
LAYER RIDGE CENTERED WELL W OF THE AREA ALONG 165W N OF 20N. AN 
ASSOCIATED A SURFACE RIDGE EXTENDS FROM 1028 MB HIGH PRES  
CENTERED NEAR 36N156W TO NEAR THE SOUTHERN TIP OF BAJA 
CALIFORNIA. ASCAT AND WINDSAT DATA FROM 03 AND 06 UTC 
RESPECTIVELY SHOW PERSISTENT 20 KT TRADES S OF 20N W OF 135W. 
THE BAND OF TRADE WINDS WILL EXPAND E GENERALLY S OF 20N OVER 
THE NEXT 48 TO 72 HOURS AS THE RIDGE BUILDS TO THE NORTH...AND 
AS WEAK 1012 MB LOW PRES NEAR 12N128W PROPAGATES W ALONG THE 
MONSOON TROUGH. S OF THE MONSOON TROUGH...ASCAT DATA AND 
TOGA-TAO BUOY DATA INDICATED GENERALLY 10 TO 15 KT SOUTHERLY 
FLOW. GLOBAL MODELS SHOW THIS INCREASING SLIGHTLY BY 48 HOURS 
BETWEEN 115W AND 120W FROM 05N TO 10N AHEAD OF ANOTHER LOW PRES 
CENTER FURTHER EAST MIGRATING W ALONG THE MONSOON TROUGH. 

E OF 115W...DIVERGENCE ALOFT ASSOCIATED WITH AN UPPER TROUGH 
THAT EXTENDS FROM ROUGHLY S FLORIDA TO GUATEMALA AIDED STRONG 
CONVECTION OVER THE GULF OF FONSECA EARLIER IN THE EVENING...BUT 
THIS HAS SINCE DIMINISHED AS THE UPPER TROUGH AXIS SHIFTED E. A 
SURFACE TROUGH OVER THE WESTERN CARIBBEAN AS BECOME MORE 
AMPLIFIED AS IT COMES INTO PHASE WITH THE UPPER TROUGH...AND 
GLOBAL MODELS SUGGEST THIS FEATURE WILL SHIFT W ACROSS SOUTHERN 
CENTRAL AMERICA AND INTO THE FAR EASTERN PACIFIC OVER THE NEXT 
24 HOURS. GLOBAL MODELS ALSO INDICATE GAP WINDS AROUND 15 TO 20 
KT THROUGH THE GULF OF TEHUANTEPEC SAT AND SUN...IN RESPONSE TO 
THE APPROACHING TROUGH. THE MONSOON TROUGH BECOMES MORE 
PERTURBED AS THE TROUGH MOVES INTO THE AREA...WITH WEAK LOW PRES 
FORMING NEAR 10N95W ALONG THE TROUGH BY MON. FURTHER W...AN 
ASCAT PASS FROM 0434 UTC CAPTURED THE 1010 MB LOW PRES NEAR 
13N102W ALONG THE MONSOON TROUGH...WITH WINDS TO 20 KT WITHIN 60 
NM IN THE NE QUADRANT. THIS LOW WILL DEEPEN SLIGHTLY AS IT 
MIGRATES WESTWARD ALONG THE MONSOON TROUGH THROUGH THE WEEKEND. 
WW3 AND ECWAVE MODELS SHOW SEAS APPROACHING 8 FT IN THIS SAME 
AREA. CONVERGENT FLOW INTO THE MONSOON TROUGH IS RESPONSIBLE FOR 
CLUSTERS OF MODERATE CONVECTION WITHIN 60 NM EITHER SIDE OF THE 
AXIS W OF 135W AND WITHIN 90 NM S OF AXIS BETWEEN 110W AND 
115W.  

$$

CHRISTENSEN