000
AXPZ20 KNHC 012141
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED AUG 01 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 
2000 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE LIES ALONG 97W N OF 09N AND IS MOVING W AROUND 
17 KT. THERE IS NO EVIDENCE OF WINDS ABOVE A MODERATE BREEZE 
ASSOCIATED WITH THIS WAVE. CONVECTION IS LIMITED TO THE S END OF 
THE WAVE WITHIN 150 NM S OF THE MONSOON TROUGH AXIS BETWEEN 94W 
AND 99W. THE WAVE LIES IN AN AREA OF RELATIVELY LOW PRECIPITABLE 
WATER VALUES AND FAIRLY SUBSIDENT MID TO UPPER FLOW ON THE EAST 
SIDE OF AN UPPER ANTICYCLONE CENTERED NEAR 15N105W. MOISTURE 
WILL CONTINUE TO BE A LIMITING FACTOR FOR THIS WAVE. IT IS 
FORECAST TO WEAKEN AS IT CONTINUES WESTWARD.

A BETTER DEFINED TROPICAL WAVE IS NOTED FROM 18N111W TO 10N113W. 
THIS WAVE IS MOVING W AT 10 KT. THE 1650 UTC ASCAT PASS SHOWS 
CYCLONIC TURNING OF THE FRESH WINDS ALONG THE WAVE AXIS FROM 12N 
TO 15N. WINDS ARE FORECAST TO DIMINISH OVERNIGHT TONIGHT NEAR 
THE WAVE AS THE SUBTROPICAL HIGH SHIFTS NW AND THE PRES GRADIENT 
WEAKENS. HOWEVER...THE LOW LEVEL CIRCULATION IS EXPECTED TO HOLD 
TOGETHER AS IT MOVES TO THE W OVER THE NEXT FEW DAYS. SCATTERED 
MODERATE CONVECTION WAS WITHIN 180 NM E OF THE WAVE FROM 10N TO 
16N. THIS WAVE LIES IN A REGION OF PLENTIFUL LOW LEVEL MOISTURE 
AND DIFFLUENT FLOW ALOFT BETWEEN ANTICYCLONES CENTERED NEAR 
16N122W AND THE AFOREMENTIONED CYCLONE NEAR 15N105W. THE WAVE 
SHOULD CONTINUE TO BE A FOCUS FOR CONVECTION OVER THE NEXT DAY 
OR SO.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 08N78W TO 10N86W TO 
09N97W. THE ITCZ AXIS WAS ANALYZED FROM 09N100W TO 12N111W THEN 
FROM 11N115W TO 06N140W. SCATTERED MODERATE CONVECTION WAS 
WITHIN 150 NM S OF THE AXIS BETWEEN 94W AND 99W. SCATTERED 
MODERATE TO STRONG CONVECTION WAS WITHIN 180 NM S OF THE AXIS W 
OF 122W.

...DISCUSSION...
THE 1030 MB SUBTROPICAL HIGH NEAR 38N137W IS FORECAST TO MOVE NW 
OVER THE NEXT TWO DAYS...WEAKENING THE RIDGING OVER THE FORECAST 
AREA. THE BELT OF FRESH TRADE WINDS CURRENTLY FOUND JUST N OF 
THE ITCZ AND W OF 125W WILL SHRINK WESTWARD BY FRI AS THE 
SUBTROPICAL HIGH MIGRATES. A STRONG SOUTH PACIFIC SUBTROPICAL 
RIDGE IS CURRENTLY IN PLACE AND IS FORCING A FRESH SE BREEZE 
PRIMARILY S OF 03N W OF 110W. BUOY 32316 NEAR 02N110W REPORTED 
18 KT AT 1400 UTC AND BUOY 51008 NEAR 02N140W REPORTED 18 KT AT 
1700 UTC WHILE THE 1652 UTC ASCAT PASS CONFIRMED THE FRESH 
BREEZE BETWEEN 110W AND 120W. THE SUBTROPICAL HIGH IN THE SOUTH 
PACIFIC SHOULD WEAKEN OVERNIGHT AND WINDS WILL DIMINISH. 
CROSS-EQUATORIAL SE TO S SWELL WILL OOZE INTO THE FORECAST AREA 
W OF THE GALAPAGOS BEGINNING LATE THU AND SPREAD TO MUCH OF THE 
AREA S OF 06N BY THE END OF THE PERIOD FRI AFTERNOON. 

A BROAD UPPER TROUGH CENTERED ALONG 130W N OF 20N WILL WEAKEN AS 
IT MOVES E TO 120W THROUGH FRI AFTERNOON. ENERGY OVER THE GULF 
OF CALIFORNIA WEDGED BETWEEN THIS TROUGH AND A VAST ANTICYCLONE 
CENTERED OVER TEXAS WILL LIFT NORTHWARD THROUGH THE GULF TODAY 
AND MEET UP WITH AN UPPER LOW OVER NW ARIZONA. THE SURFACE 
REFLECTION OF THE ENHANCED TROUGHING ALOFT SHOULD ALLOW THE PRES 
GRADIENT TO INCREASE ENOUGH ALONG THE PACIFIC COAST OF BAJA 
CALIFORNIA TO SUPPORT NW WINDS BRIEFLY BECOMING A FRESH BREEZE 
THU EVENING INTO EARLY FRI MORNING BEFORE DIMINISHING. 

STRONG UPPER LEVEL DIFFLUENCE BETWEEN 30-40 KT SOUTHWESTERLIES 
ON THE S SIDE OF THE BROAD TROUGH ALONG 130W AND WEAK 
ANTICYCLONIC FLOW S OF THE RIDGE AXIS THAT EXTENDS FROM THE 
ANTICYCLONE AT 16N122W TO 10N135W IS ENHANCING CONVECTION ALONG 
THE ITCZ AXIS W OF 122W. THERE IS PLENTIFUL MOISTURE POOLED 
ALONG THE ITCZ. THESE CONDITIONS ARE EXPECTED TO CONTINUE FOR 
THE NEXT DAY OR SO. 

$$
SCHAUER