000
AXPZ20 KNHC 160315
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED DEC 16 2009

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0145 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS ALONG 05N77W TO 
07N105W TO 06N115W TO 07N128W TO 06N140W. SCATTERED MODERATE 
WITH ISOLATED STRONG CONVECTION CAN BE FOUND WITHIN 120 NM 
EITHER SIDE OF THE ITCZ AXIS W OF 127W.

...DISCUSSION...
AN AMPLIFIED NORTHERN STREAM PATTERN IS IN PLACE WITH A SHARP 
UPPER TROUGH FOUND FROM THE TEXAS BIG BEND THROUGH THE MOUTH OF 
THE GULF OF CALIFORNIA TO 10N118W. A 120 KT JET LIES ON THE 
LEADING EDGE OF THIS TROUGH. THIS JET IS TRANSPORTING MID TO 
UPPER LEVEL TROPICAL MOISTURE NORTHEASTWARD THROUGH THE CENTRAL 
MEXICAN COAST TO THE EASTERN RIO GRANDE VALLEY. NEAR THE TAIL OF 
THE JET...THE 1614 UTC ASCAT PASS HINTS THAT A LOW PRES SYSTEM 
HAS FORMED NEAR 07N108W ALONG A SURFACE TROUGH FROM 13N105W TO 
04N108W. THE CENTRAL PRES OF THE LOW IS ESTIMATED AT 1010 MB. 
THAT ASCAT PASS SHOWS 20 KT WINDS IN THE NE QUADRANT OF THE LOW. 
SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 240 NM NE 
QUADRANT...BUT THERE IS A DECIDED LACK OF DEEP CONVECTION HERE 
DESPITE THE DIFFLUENCE ALOFT AND AVAILABLE MOISTURE. TOTAL 
PRECIPITABLE WATER SATELLITE IMAGERY SHOWS THE LOW TO MID LEVEL 
MOISTURE POOLED ALONG THIS SURFACE TROUGH AS WELL AS ALONG AND W 
OF ANOTHER SURFACE TROUGH FROM 12N127W TO 06N130W. AS MENTIONED 
IN THE ITCZ SECTION...SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION CAN BE FOUND WITHIN 120 NM EITHER SIDE OF THE ITCZ 
AXIS W OF 127W IN ASSOCIATION WITH THIS SECOND TROUGH. THIS 
TROUGH LIES UNDER A DIFFLUENT REGION ASSOCIATED WITH AN UPPER 
ANTICYCLONE NEAR 06N135W. THE DIFFLUENCE DUE TO THE ANTICYCLONE 
IS LIFTING THE POOLED MOSITURE AND ALLOWING FOR SUSTAINED DEEP 
CONVECTION. 

THE AMPLIFIED LONGWAVE PATTERN ALOFT SHOULD BE SLOW TO CHANGE. 
THE MEAN UPPER TROUGH OVER MEXICO WILL RELOAD THU WITH 
SHORTWAVE ENERGY CURRENTLY ASSOCIATED WITH THE WEAKENING 
STATIONARY FRONT OVER NW WATERS FROM 30N135W TO 26N140W. NW 
SWELL HAS ACCOMPANIED THIS FRONTAL SYSTEM INTO NW WATERS...WITH 
SEAS AS HIGH AS 17 FEET EXPECTED TO MOVE INTO THE REGION WED BUT 
DECAY TO THE 12 TO 14 FT RANGE AS IT MIGRATES SOUTHEASTWARD THU. 
MEANWHILE...THAT SHORTWAVE ENERGY ALOFT WILL HAVE TO PASS OVER 
THE UPPER RIDGE AXIS CURRENTLY EXTENDING FROM THE AFOREMENTIONED 
ANTICYCLONE NEAR 06N135W TO 30N120W. THE DEEP LAYER RIDGE AXIS 
WILL SHIFT SLIGHTLY TO THE W AS THE TROUGHS TO ITS E AND W 
RELOAD WITH ENERGY MOVING INTO THEIR WESTERN EDGES. THE PRES 
GRADIENT BETWEEN THE SURFACE RIDGE STEMMING FROM 1023 MB HIGH 
PRES NEAR 31N121W EXTENDING TO 20N140W AND THE WESTERN SURFACE 
TROUGH HAS INDUCED 20 TO 25 KT TRADE WINDS IN MUCH OF THE REGION 
BETWEEN 07N AND 17N W OF 120W. THE SLIGHT WESTWARD MIGRATION OF 
THE DEEP LAYER RIDGE WILL SHIFT THE TRADES SLIGHTLY WESTWARD AND 
PREVENT THE NEXT FRONTAL SYSTEM ASSOCIATED WITH THE LONGWAVE 
TROUGH IN THE CENTRAL PACIFIC FROM PUSHING INTO NW WATERS. 
HOWEVER...SW WINDS ARE EXPECTED TO REACH 20 KT THERE BY THIS 
TIME TOMORROW AHEAD OF THE FRONT. THESE CONDITIONS WILL CONTINUE 
INTO THU. 

CLOSER TO LAND...THE 1748 UTC ASCAT AND 1308 UTC WINDSAT PASSES 
SHOW WINDS IN THE 20 TO 25 KT RANGE CONTINUE IN THE GULF OF 
CALIFORNIA. SHIP REPORTS SUPPORT 20 KT WINDS AS FAR SOUTH AS 18N 
TO THE MOUTH OF THE GULF. AS HIGH PRES MOVES EASTWARD BEHIND THE 
COLD FRONT CURRENTLY OVER THE NORTHERN GULF OF MEXICO...EXPECT 
THE PRES GRADIENT TO DECREASE ACROSS THE GULF OF CALIFORNIA AND 
WINDS WILL STEP DOWN A NOTCH TO 20 KT N OF 25N IN THE GULF OF 
CALIFORNIA.

GAP WINDS...GAP WINDS PERSIST THROUGH THE GULFS OF PAPAGAYO AND 
TEHUANTEPEC. THE COMBINATION OF STRONG TRADE WINDS IN THE 
CARIBBEAN AND LOCAL DRAINAGE EFFECTS WILL ALLOW THE FRESH WINDS 
TO PERSIST IN PAPAGAYO THROUGH WED NIGHT...DIMINISHING THROUGH 
THU. WINDS WILL INCREASE THROUGH THE GULF OF TEHUANTEPEC BY 
EARLY WED AS THE COLD FRONT PUSHES INTO THE SW GULF OF MEXICO. 
WINDS WILL REACH NEAR GALE BY WED NIGHT AS THE COLD DENSE AIR 
FUNNELS THROUGH THE ISTHMUS AND INTO THE ADJACENT PACIFIC 
WATERS. 

FOR ADDITIONAL INFORMATION PLEASE VISIT 
HTTP://WWW.HURRICANES.GOV/MARINE
  
$$
SCHAUER