000
AXPZ20 KNHC 031603
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT SEP 03 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.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM 16N108W TO 13N116W TO 14N130W TO 
13N140W. NO INTERTROPICAL CONVERGENCE ZONE AXIS IS NOTED. 
SCATTERED MODERATE FROM 07N TO 11N BETWEEN 118W AND 125W AND 
WITHIN 120 NM S OF MONSOON TROUGH BETWEEN 129W AND 135W.

...DISCUSSION...
BLOCKING PATTERN ALOFT PERSISTS ACROSS THE AREA TODAY. A BROAD 
MIDDLE TO UPPER LEVEL TROUGH COVERS THE AREA N OF 18N BETWEEN 
122W AND 142W WITH A CUT-OFF LOW NEAR 27N131W. UPPER LEVEL 
RIDGING EXTENDS NEARLY E TO W ACROSS MEXICO AND INTO EPAC ALONG 
22N-24N...WITH TWO UPPER ANTICYCLONES...ONE NEAR 23N105W WHILE 
THE SECOND LARGER AND MORE DOMINANT CENTER IS NEAR 25N112W. 
CYCLONIC SHEAR BETWEEN THESE TWO ANTICYCLONIC CELLS IS HELPING 
TO MAINTAIN MIDDLE LEVEL TROUGHING ASSOCIATED WITH THE REMNANTS 
OF THE FORMER T.D. EIGHT-E ACROSS THE MOUTH OF THE GULF OF 
CALIFORNIA. SOUTH TO THIS RIDGE...NE TO E FLOW ALOFT 
PERSISTS...YIELDING LIGHT TO MODERATE VERTICAL WIND SHEAR OF 20 
KT OR LESS ACROSS THE DEEP TROPICS. A SIGNIFICANT PATTERN CHANGE 
ACROSS THE AREA IS EXPECTED NEXT WEEK AS THE UPPER TROUGH WILL 
EVENTUALLY WEAKEN AND LIFT OUT TO THE NE. 

AT THE SURFACE...HIGH PRES REMAINS CENTERED WELL N OF THE 
DISCUSSION AREA...WITH A 1025 MB HIGH NEAR 44N135W AND A SECOND 
1023 MB HIGH NEAR 33N152W. A NEARLY STATIONARY 1010 MB LOW ALONG 
THE COAST OF NORTHERN CALIFORNIA WITH A DYING FRONTAL TROUGH 
EXTENDS WELL SW SEPARATES THE TWO HIGH CENTERS. A WEAK SURFACE 
RIDGE THUS EXTENDS ESE ACROSS THE AREA FROM THE HIGH NEAR 
33N152W TO NEAR 27N117W PRODUCING A MILD PRESSURE GRADIENT 
ACROSS THE LOCAL AREA. TRADEWINDS REMAIN BELOW 20 KT E OF 140W 
UNDER THE INFLUENCE OF THIS WEAK RIDGE...WITH SEAS 7 TO 9 FT IN 
A MIX OF LONG PERIOD SRN HEMI SLY SWELL AND MODERATE NLY SWELL. 

THE REMNANTS OF T.D. EIGHT-E ARE NOTED ON VISIBLE SATELLITE 
IMAGERY THIS MORNING ACROSS THE MOUTH OF THE GULF OF 
CALIFORNIA...PRODUCING MODERATE BUT WEAKENING CONVECTION...AND 
REMAINS EMBEDDED WITHIN THE S END OF THE SEMIPERMANENT BAJA 
CALIFORNIA TROUGH. A BROAD CYCLONIC LOW TO MID LEVEL GYRE 
ASSOCIATED WITH THIS FORMER T.D. CONTINUES TO TRANSPORT TROPICAL 
MOISTURE FROM THE EPAC N  AND NE ACROSS ALL BUT NORTHERN MEXICO 
AND INTO THE GULF OE MEXICO...WHERE IT IS ALSO FEEDING INTO 
TROPICAL STORM LEE. EXPECT THIS MOIST PATTERN TO CONTINUE 
THROUGH MONDAY.

FURTHER SOUTH...BROAD MONSOONAL FLOW IS OCCURRING ACROSS THE 
AREA S AND E OF THE MONSOON TROUGH DEFINED ABOVE...AND IS 
GENERALLY LESS THAN 20 KT ACROSS THE AREA WITH A FEW VERY SMALL 
AREAS NEAR 20 KT DEPICTED BY OVERNIGHT SCATTEROMETER PASSES. AN 
ELONGATED ZONE OF GOOD LOW LEVEL CONVERGENCE WAS YIELDING 
SCATTERED MODERATE CONVECTION FROM 07N-11N BETWEEN 90W AND 125W. 
THIS PATTERN WILL GENERALLY HOLD THROUGH THE NEXT FEW DAYS.

$$
STRIPLING