000
AXPZ20 KNHC 021546
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1515 UTC.

...ITCZ/MONSOON TROUGH...
MONSOON TROUGH MEANDERS ACROSS CENTRAL AMERICA AND EXITS THE 
MEXICAN COAST NEAR 16.5N99W TO 15N110W TO 17N118W TO 12N140W.  
SCATTERED MODERATE TO STRONG CONVECTION NOTED N OF 04N E OF 
81W...N OF 06N BETWEEN 86W AND 92W...WITHIN 120 NM OF MEXICAN 
COASTLINE FROM 101W TO 106W...AND FROM 5N-10N BETWEEN 98W AND 
107W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED 
ELSEWHERE 10N-13N W OF 118W. 

...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 28N129W. UPPER 
LEVEL RIDGING EXTENDS NEARLY E TO W ACROSS MEXICO AND INTO EPAC 
ALONG 21N-22N...WITH TWO ANTICYCLONES SEPARATED BY THE REMNANTS 
OF FORMER T.D. EIGHT-E ALONG COASTAL MEXICO...CENTERED IN THE 
VICINITY OF 20N106.5W. SE 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 1031 MB DOUBLE BARREL HIGHS ON EITHER 
SIDE OF 41N141W. A WEAK SURFACE RIDGE EXTENDS SE TO NEAR 22N125W 
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 ACROSS CENTRAL AMERICA AND SE 
MEXICO...WITH BROAD MONSOONAL FLOW OCCURRING S OF 12N-13N ACROSS 
THE ENTIRE AREA. STRONG LOW LEVEL CONVERGENCE WAS PRODUCING 
SIGNIFICANT AREAS OF DEEP CONVECTION BETWEEN 101W-106W AND E OF 
80W. THE POSITION OF THE MONSOON TROUGH WAS ALSO AIDING IN 
TRANSPORTING TROPICAL EPAC MOISTURE ACROSS CENTRAL AMERICA AND 
THE YUCATAN PENINSULA AND INTO THE SE GULF OF MEXICO. A BROAD 
MID LEVEL GYRE ASSOCIATED WITH THE REMNANTS OF FORMER TD EIGHT-E 
WAS ALSO PROVIDING ABUNDANT MOISTURE ACROSS THE COASTAL REGIONS 
OF W CENTRAL MEXICO.  

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

$$
STRIPLING