000
AXPZ20 KNHC 151653
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN NOV 15 2009

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1330 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS CENTERED ALONG A LINE FROM 
07N77W TO 10N115W TO 07N125W TO 09N131W TO 08N140W. SCATTERED 
MODERATE CONVECTION CAN BE FOUND WITHIN 120 NM N OF THE ITCZ 
AXIS W OF 137W. ISOLATED MODERATE CONVECTION LIES WITHIN 180 NM 
S OF THE ITCZ AXIS BETWEEN 123W AND 137W.

...DISCUSSION...

AN AMPLIFIED UPPER PATTERN IS IN PLACE N OF 15N WITH A TROUGH 
EXTENDING FROM W TX SOUTHWESTWARD THROUGH THE SOUTHERN HALF OF 
THE BAJA PENINSULA TO 20N120W AND TO 16N130W. AN UPPER JET LIES 
JUST E OF THE TROUGH AXIS...WITH SW TO W WINDS IN EXCESS OF 60 
KT INHIBITING CONVECTION OVER MUCH OF THE AREA N OF 20N. UPPER 
LEVEL DIFFLUENCE ASSOCIATED WITH THE REAR RIGHT QUADRANT OF THIS 
JET IS ENHANCING CONVECTION OVER W WATERS NEAR A SURFACE TROUGH 
FROM 14N129W TO 07N132W EMBEDDED IN THE ITCZ. SATELLITE 
PRECIPITABLE WATER IMAGERY SHOWS A POOL OF MOISTURE IN THIS 
REGION...WITH PRECIPITABLE WATER VALUES IN EXCESS OF 2.25 
INCHES. WHILE THE LEADING EDGE OF THE UPPER TROUGH IS EXPECTED 
TO SHIFT ACROSS MEXICO OVER THE NEXT FEW DAYS...THE REAR RIGHT 
QUADRANT OF THE UPPER JET WILL REMAIN OVER W WATERS AND ALLOW 
FOR AN INCREASED CHANCE OF CONVECTION.

A DEEP LAYER RIDGE LIES OVER NW WATERS WITH THE SURFACE RIDGE 
AXIS ALONG A LINE FROM 15N105W TO 30N128W TO A 1028 MB SURFACE 
HIGH NEAR 34N135W. THE PRES GRADIENT BETWEEN THIS RIDGE AND THE 
AFOREMENTIONED SURFACE TROUGHING OVER W WATERS AND ALONG THE 
ITCZ IS SUPPORTING A LARGE AREA OF 20 TO 25 KT NE TO E TRADE 
WINDS S OF THE RIDGE AXIS. THESE TRADES ARE EXPECTED TO PERSIST 
INTO MON WITH LITTLE CHANGE EXPECTED IN THE PRES GRADIENT. BY 
TUE...A COLD FRONT IS EXPECTED TO APPROACH NW WATERS AND WEAKEN 
THE RIDGE AS ITS SHIFTS SW IN ADVANCE OF THE FRONT. THE AREA OF 
TRADE WINDS SHOULD SHIFT W AS WELL.

AN ANTICYCLONE IS CENTERED NEAR THE W COAST OF NICARAGUA WITH A 
RIDGE AXIS THAT EXTENDS NW TO 15N95W AND THEN SW TO 10N120W. 
UPPER LEVEL DIFFLUENCE ON THE WESTERN EDGE OF THIS RIDGE AXIS IS 
SUPPORTING SOME ISOLATED MODERATE CONVECTION FROM 11N TO 14N 
BETWEEN 111W AND 116W. CLOSER TO THE ANTICYCLONE...SCATTERED 
MODERATE WITHIN 90 NM OF COAST OF COLOMBIA FROM 02N TO 07N. 
MEANWHILE...TO THE S OF THE RIDGE AXIS...A 1009 MB LOW PRES 
SYSTEM NEAR 07N93W HAS SCATTERED MODERATE CONVECTION WITHIN 75 
NM E SEMICIRCLE. WHILE THERE IS PLENTY OF LOW LEVEL MOISTURE 
NEAR THIS LOW...CONDITIONS ALOFT ARE EXPECTED TO BECOME LESS 
FAVORABLE FOR ANY DEVELOPMENT AS IT MOVES W TO SW OVER THE NEXT 
TWO DAYS TOWARD INCREASING SW FLOW ALOFT. THE LOW IS EXPECTED TO 
DISSIPATE OVER THE NEXT DAY OR TWO.

GAP WINDS...
THE COMBINATION OF THE HIGH PRES RIDGE TO THE W OF THE BAJA 
PENINSULA...A DEVELOPING TROUGH OF LOW PRES ALONG THE E GULF OF 
CALIFORNIA COAST...AND BUILDING HIGH PRESSURE OVER THE U.S. 
GREAT BASIN WILL CREATE A TIGHT PRES GRADIENT WHICH WILL RESULT 
IN INCREASING NW WINDS IN THE GULF OF CALIFORNIA INCREASING TO 
20 KT LATER TODAY. SUSTAINED WINDS OF 20 TO 30 KT WITH BRIEF 
HIGHER GUSTS ARE EXPECTED THIS EVENING THROUGH MON. THE 
STRONG NW WINDS WILL THEN GRADUALLY DIMINISH BY MID WEEK AS THE 
HIGH PRES RIDGE TO THE WEST WEAKENS.

A STRONG COLD FRONT ASSOCIATED WITH THE AFOREMENTIONED UPPER 
TROUGH MOVING E INTO MEXICO WILL APPROACH THE S GULF OF MEXICO 
AND BAY OF CAMPECHE LATE MON NIGHT. N TO NE WINDS WILL FUNNEL 
THROUGH THE ISTHMUS OF TEHUANTEPEC AND WILL INCREASE TO 20 TO 30 
KT IN THE GULF OF TEHUANTEPEC BY TUE MORNING. MANY OF THE 
FORECAST MODELS ALLOW THE WINDS TO REACH GALE FORCE HERE ON TUE 
AFTERNOON...JUST BEYOND THE FORECAST PERIOD. IN ADDITION...NE TO 
E WINDS IN THE 20 TO 25 KT RANGE WILL BE POSSIBLE IN THE GULF OF 
PAPAGAYO BY TUE NIGHT.

$$
SCHAUER