000
AXPZ20 KNHC 022158
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI SEP 02 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2130 UTC.

...ITCZ/MONSOON TROUGH...
MONSOON TROUGH FROM 11N85W TO 11N95W RESUMES AT 17N102W TO 
13N115W TO 15125W TO 11N140W. SCATTERED MODERATE N OF 06N E OF 
82W...FROM 08N TO 11N BETWEEN 102W AND 110W...WITHIN 120 NM OF 
MEXICAN COASTLINE FROM 16W TO 22W...FROM 11N TO 13N BETWEEN 120W 
AND 130W...AND WITHIN 50 NM S OF THE MONSOON TROUGH W OF 138W. 

...DISCUSSION...
UPPER LEVEL PATTERN REMAINS REMARKABLY SIMILAR TO RECENT WEEKS 
ACROSS THE DISCUSSION AREA AS BROAD SCALE BLOCKING PATTERN 
PERSISTS ACROSS N AMERICA AND ADJACENT OCEANIC AREAS. BROAD 
MIDDLE TO UPPER LEVEL TROUGH COVERS THE AREA N OF 17N BETWEEN 
120W AND 142W WITH MID LEVEL CYCLONE NOTED NEAR 28N130W. UPPER 
LEVEL RIDGING EXTENDS NEARLY E TO W ACROSS MEXICO AND INTO EPAC 
ALONG 21N-22N...WITH TWO UPPER ANTICYCLONES SEPARATED BY THE 
REMNANTS OF FORMER T.D. EIGHT-E ACROSS THE TRES MARIAS ISLANDS 
ALONG COASTAL MEXICO. S THROUGH SE TO THIS RIDGE...NE TO ELY 
FLOW ALOFT PERSISTS...YIELDING LIGHT TO MODERATE SHEAR ALOFT 
ACROSS THE DEEP TROPICS.

AT LOWER LEVELS...HIGH PRES REMAINS CENTERED WELL N OF THE 
DISCUSSION AREA...WITH A 1029 MB HIGH NEAR 44N136W. A WEAK 
SURFACE RIDGE EXTENDS SE TO NEAR 25N120W PRODUCING MILD PRESSURE 
GRADIENT ACROSS THE LOCAL AREA...WITH FRESH TRADES AT 20 KT OR 
GREATER OCCURRING W OF 140W. THE FORMER T.D. EIGHT-E AND THE 
EVOLUTION OF THE T.D. ACROSS THE GULF OF MEXICO HAVE PULLED THE 
MONSOON TROUGH WELL NORTH OF ITS TYPICAL POSITION...AND NOW 
RESIDES ALONG THE PACIFIC COASTS OF CENTRAL AMERICA AND SE 
MEXICO...WITH BROAD MONSOONAL FLOW OCCURRING S OF 12N-13N ACROSS 
THE AREA E OF 135W...GENERALLY AT 10 TO 15 KT WITH A FEW SMALL 
AREAS OF 15-20 KT BETWEEN 95W AND 120W. STRONG LOW LEVEL 
CONVERGENCE WAS PRODUCING SIGNIFICANT DEEP CONVECTION ALONG 10N 
FROM 104W-119W. THE POSITION OF THE MONSOON TROUGH WAS ALSO 
AIDING IN TRANSPORTING TROPICAL EPAC MOISTURE ACROSS CENTRAL 
AMERICA AND THE YUCATAN PENINSULA AND INTO THE GULF OF MEXICO. A 
LOW TO MID LEVEL CYCLONIC GYRE ASSOCIATED WITH THE REMNANTS OF 
FORMER TD EIGHT-E WAS ALSO PROVIDING ABUNDANT MOISTURE ACROSS 
THE COASTAL REGIONS OF W CENTRAL MEXICO AND SPREADING NNW INTO S 
PORTIONS OF THE GULF OF CALIFORNIA AND ACROSS THE SIERRA MADRES 
OCCIDENTALES.  

LONG PERIOD SRN HEMI SWELL CONTINUES TO DOMINATE THE REGIONAL 
WATERS THIS AFTERNOON AND WILL GRADUALLY FADE THROUGH SATURDAY 
NIGHT. WINDS HAVE BEGUN TO INCREASE SOME JUST W OF THE BAJA 
CALIFORNIA PENINSULA THIS AFTERNOON AND WILL CONTINUE THROUGH 
SUN AS THE PRES GRADIENT TIGHTENS THERE...WHERE MARINE GUIDANCE 
SUGGESTS NW WINDS NEAR 20 KT AND SEAS TO 8 FT.

$$
STRIPLING