000
AXPZ20 KNHC 161510
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON NOV 16 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 
0330 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS CENTERED ALONG A LINE FROM 
05N77W TO 08N95W TO 05N105W TO 10N120W TO 09N140W. SCATTERED 
MODERATE CONVECTION CAN BE FOUND WITHIN 150 NM EITHER SIDE OF 
THE ITCZ AXIS E OF 83W AS WELL AS WITHIN 60 NM EITHER SIDE OF 
THE ITCZ AXIS BETWEEN 127W AND 134W.

...DISCUSSION...

AN AMPLIFIED UPPER PATTERN IS IN PLACE N OF 15N WITH A TROUGH 
EXTENDING FROM NORTH CENTRAL MEXICO TO MAZATLAN AND OFFSHORE 
THROUGH 21N113W TO 19N125W. AN UPPER JET LIES IN THE VICINITY OF 
THE TROUGH AXIS AND EXTENDS SW TO NEAR 16N140W...WITH SW TO W 
WINDS IN EXCESS OF 70 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 TWO SURFACE TROUGHS EMBEDDED IN THE ITCZ FROM 15N122W TO 
08N123W AND FROM 14N133W TO 07N135W...RESPECTIVELY. 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 CONTINUE TO SHIFT E 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 SHOWERS AND 
THUNDERSTORMS.

A DEEP LAYER RIDGE CURRENTLY LIES OVER NW WATERS WITH THE 
SURFACE RIDGE AXIS ALONG A LINE FROM 17N110W TO 30N128W TO A 
1024 MB SURFACE HIGH NEAR 32N131W. 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. 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. THE COLD FRONT WILL USHER IN 20 TO 25 KT 
NE WINDS OVER NW WATERS TUE AND WED...WITH SEAS EXPECTED TO 
REACH 16 FT IN NW SWELL.

AN ANTICYCLONE IS CENTERED S OF THE GULF OF TEHUANTEPEC NEAR 
12N95W WITH A RIDGE AXIS THAT EXTENDS ALONG 95W FROM THE EQUATOR 
TO TEHUANTEPEC. THE DIFFLUENT UPPER LEVEL FLOW ASSOCIATED WITH 
THIS ANTICYCLONE IS CREATING AN ENVIRONMENT FAVORABLE FOR 
CONVECTION. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 60 
NM E SEMICIRCLE OF THE 1010 MB SURFACE LOW PRES SYSTEM FOUND 
NEAR 08N96W AS A RESULT. THE EASTWARD MOVING UPPER TROUGH TO ITS 
NW WILL CAUSE THE PORTION OF THE RIDGE AXIS OVER THE PACIFIC TO 
SHIFT SW...WITH THE SURFACE LOW EXPECTED TO TRACK W WITH IT.  
THIS WILL ALLOW THE LOW TO CONTINUE TO BE A FOCUS FOR CONVECTION.

GAP WINDS...
THE COMBINATION OF THE HIGH PRES RIDGE TO THE W OF THE BAJA 
PENINSULA...A TROUGH OF LOW PRES ALONG THE E GULF OF CALIFORNIA 
COAST...AND HIGH PRESSURE OVER THE U.S. GREAT BASIN CREATED A 
TIGHT PRES GRADIENT WHICH RESULTED IN NW WINDS IN THE GULF OF 
CALIFORNIA TO 30 KT ACCORDING TO THE 0212 UTC QUIKSCAT PASS. 
THESE STRONG NW WINDS WILL GRADUALLY DIMINISH BY MID WEEK AS THE 
HIGH PRES RIDGE TO THE WEST WEAKENS AND THE HIGH CENTER OVER THE 
GREAT BASIN SHIFTS SE INTO THE GULF OF MEXICO BEHIND THE COLD 
FRONT. THIS STRONG COLD FRONT IS ASSOCIATED WITH THE 
AFOREMENTIONED UPPER TROUGH MOVING E THROUGH MEXICO. THE COLD 
FRONT WILL APPROACH THE S GULF OF MEXICO AND BAY OF CAMPECHE 
TONIGHT. N TO NE WINDS WILL FUNNEL THROUGH THE ISTHMUS OF 
TEHUANTEPEC AND WILL INCREASE TO GALE FORCE IN THE GULF OF 
TEHUANTEPEC BY TUE MORNING. IN ADDITION...NE TO E WINDS IN THE 
20 TO 25 KT RANGE ARE EXPECTED IN THE GULF OF PAPAGAYO BY WED 
MORNING.

$$
SCHAUER