000
AXPZ20 KNHC 051005
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON APR 05 2010

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0945 UTC.

...ITCZ...

AXIS IS CENTERED ALONG 5N77W TO 6N90W TO 4N105W TO 2N115W 2N126W
3N140W. SCATTERED STRONG CONVECTION WAS WITHIN 60 NM S OF THE AXIS
BETWEEN 135W AND 139W. SCATTERED MODERATE CONVECTION WAS WITHIN 
30 NM OF 4N130W.

...DISCUSSION...

A BROAD UPPER TROUGH COVERS THE AREA N OF 25N AND E TO INLAND 
THE WESTERN UNITED STATES. STRONG NW 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 131W. TWO JET STREAM
BRANCHES...ONE FROM NW AND THE OTHER FROM W...MERGE OVER THE NE 
PORTION ON THE SE SIDE OF THE TROUGH. THE ASSOCIATED SURFACE COLD
FRONT ENTERS THE AREA AT 30N15W...AND EXTENDS TO 27N135W AS A DISSIPATING
FRONT. RECENT SHIP OBSERVATIONS SHOWED W-NW WINDS OF 20-25 KT W OF
THE FRONT TO 133W. THE TROUGH WILL PUSH TO WELL INLAND THE 
WESTERN U.S. TONIGHT INTO TUE AS A MID/UPPER LEVEL ANTICYCLONE 
W OF THE AREA NEAR 29N144W MOVES INTO THE FAR NW CORNER BY TUE 
AFTERNOON. THE COLD FRONT WILL MOVE INLAND NW MEXICO TUE AND 
DISSIPATE. A 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 
KT WILL INCREASE OVER THE NORTHERN PORTION OF THE GULF OF CALIFORNIA
BY WED.

TO THE S AND SE OF THE TROUGH...THE UPPER FLOW PATTERN IS GENERALLY
STEERED BY TWO ANTICYCLONIC CENTERS ONE NEAR 6N124W AND A 
MUCH LARGER ONE NEAR 9N96W. MODERATE SWLY FLOW BETWEEN THE 
ANTICYCLONES AND THE TROUGH IS ALLOWING FOR 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 129W 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 U.S 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 SOME AS IT EXPANDS EASTWARD.

OTHERWISE...REMAINDER OF E PAC N OF ITCZ W OF UPPER TROUGH AXIS 
IS UNDER BROAD RIDGING. A DRY AND RELATIVELY STABLE AIR MASS 
WITH SCATTERED TO BROKEN STRATIFIED LOW LEVEL CLOUDS VOID OF ANY 
DEEP CONVECTION PREVAILS.

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

$$
AGUIRRE