000
AXPZ20 KNHC 051447
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON APR 05 2010

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 
1445 UTC.

...ITCZ...

AXIS IS CENTERED ALONG 04N77W TO 05N85W TO 02N110W TO 03N140W. 
SCATTERED MODERATE ISOLATED STRONG WITHIN 120-180 NM EITHER SIDE 
OF THE AXIS W OF 127W. SCATTERED MODERATE WITHIN 60-90 NM EITHER 
SIDE OF AXIS E OF 92W.   

...DISCUSSION...

A BROAD UPPER TROUGH COVERS THE AREA N OF 25N AND EXTENDING 
EWD OVER THE WESTERN UNITED STATES. STRONG NW FLOW ORIGINATING 
FROM WELL N OF THE AREA DIVES SE INTO THE BACK SIDE OF THE 
TROUGH...AND ROUNDS THE BASE OF THE TROUGH N OF 27N BETWEEN 120W 
AND 130W. TWO JET STREAM BRANCHES...POLAR JET FROM THE NW AND A 
SUBTROPICAL JET FROM THE DEEP TROPICS MERGE OVER THE NE PORTION
OF THE DISCUSSION AREA GENERALLY SE OF THE TROUGH AXIS. THE 
ASSOCIATED WEAKENING SURFACE COLD FRONT ENTERS THE AREA NEAR 
30N125W AND EXTENDS TO 27N135W. 12 UTC SHIP OBSERVATIONS STILL 
SHOWED W-NW WINDS OF 20 KT W OF THE FRONT BETWEEN 129W AND 134W 
WITH COMBINED SEAS OF 15-16 FT. 

THE UPPER LEVEL TROUGH WILL CONTINUE TO SLIDE EWD OVER THE 
W-CENTRAL CONUS OVER THE NEXT FEW DAYS AS A MID/UPPER LEVEL 
ANTICYCLONE W OF THE AREA NEAR 29N144W MOVES INTO THE FAR NW 
CORNER BY LATE TUE. THE COLD FRONT WILL MOVE INLAND OVER NW 
MEXICO TUE AND DISSIPATE. LARGE NW SWELL TRAIN WILL GENERATE 
COMBINED SEAS OF POSSIBLY UP TO 16 FT IN LONG PERIOD SWELLS 
BEHIND THE FRONT OVER THE WATERS N OF 28N BETWEEN 122W-135W. 
ELSEWHERE N OF 21N W OF 110W SEAS WILL BE 8-13 FT IN NW TO N 
SWELL. SWELLS WILL BEGIN TO SLOWLY SUBSIDE BEGINNING WED.

WITH RIDGING BUILDING ESE BEHIND THE FRONT...THE PRES GRADIENT
BETWEEN IT AND LOWER PRES OVER THE SW U.S. WILL RESULT IN N WINDS
OF 20-25 KT ALONG THE BAJA CALIFORNIA COAST N OF 24N W TO 116W
WITH SEAS IN THE RANGE 8-11 FT. LITTLE OVERALL CHANGE IS EXPECTED
WITH THESE THROUGH TUE THEN DIMINISH WED...HOWEVER NW WINDS OF 
20 TO 25 KT...POSSIBLY UP TO 20 KT WILL INCREASE OVER THE 
NORTHERN PORTION OF THE GULF OF CALIFORNIA TUE EVENING INTO 
WED.

TO THE S AND SE OF THE TROUGH...THE UPPER FLOW PATTERN IS 
GENERALLY GOVERNED BY TWO ANTICYCLONIC CENTERS ONE NEAR 6N124W 
AND A MUCH LARGER ONE NEAR 10N92W. MODERATE SWLY FLOW BETWEEN 
THE ANTICYCLONES AND THE TROUGH IS ADVECTING PATCHES OF MID TO 
UPPER LEVEL TROPICAL MOISTURE FROM THE CENTRAL PACIFIC ITCZ 
NORTHEASTWARD AND EASTWARD ACROSS CENTRAL MEXICO...AND INTO THE 
WESTERN GULF OF MEXICO. A WEAK MID LEVEL TROUGH IS EMBEDDED IN 
THE SWLY FLOW FROM 21N110W TO 14N112W TO NEAR 8N115W. AT THE 
SURFACE...WEAK TROUGHS ARE ANALYZED ALONG 131W S OF 7N AND ALONG 
139W S OF 8N. THE TROUGHS ARE MOVING W ABOUT 10-15 KT. DIFFLUENT 
FLOW ALOFT IS AIDING CONVECTION WITHIN 120 NM E OF THE TROUGH 
ALONG 139W AS MENTIONED ABOVE UNDER ITCZ...AND ON THE TROUGH 
ALONG 129W WHERE IT BISECTS THE ITCZ.

WITH A SERIES OF STRONG FRONTAL SYSTEMS N OF THE AREA 
APPROACHING THE UNITED STATES W COAST THROUGH THE NEXT 48 
HRS...HIGH PRES WILL BE SHUNTED S INTO THE AREA AS NEW AREAS OF 
STRONGER HIGH PRES N OF THE AREA MIGRATE E BEHIND THESE SYSTEMS. 
THIS PATTERN WILL ALLOW FOR THE CURRENT AREA OF TRADES 
CONSISTING OF NE 20 KT WINDS FROM 8N-21N W OF 124W TO INCREASE 
AND INTENSITY AND EXPAND EASTWARD.

GAP WINDS...
A FEW MORE PULSES OF FRESH EASTERLY TRADES THROUGH THE NORTHERN 
COAST COSTA RICA WILL RESULT IN NE TO E WINDS OF 20 KT THROUGH 
THE GULF OF PAPAGAYO...BUT SHOULD SUBSIDE IN ABOUT 36 HRS WITH 
WEAKENING OF THE GRADIENT AND WINDS THROUGHOUT THIS AREA.

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

$$
COBB