000
AXPZ20 KNHC 070936
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED APR 07 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 
0930 UTC.

...ITCZ...

AXIS WAS CENTERED ALONG 3N78W 6N91W 5N103W 4N111W 4N125W 4N140W. 
SCATTERED STRONG CONVECTION WAS WITHIN 120 NM N OF THE AXIS 
BETWEEN 128W-130W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION 
WAS NOTED FROM 2N-8N BETWEEN 110W-116W...AND WITHIN 120 NM S OF 
THE AXIS BETWEEN 93W-97W. SCATTERED MODERATE CONVECTION WAS 
WITHIN 120 NM S OF THE AXIS BETWEEN 101W-104W.

...DISCUSSION...

THE TAIL END OF A LONG WAVE TROUGH EXTENDED SW FROM THE SW U.S.
INTO THE AREA TO NEAR 27N119W. BROAD MID/UPPER LEVEL RIDGING
COVERS THE AREA W OF THE TROUGH WITH A AN ELONGATED WEAK MID
LEVEL CYCLONIC CIRCULATION MOVING E 20 KT UNDER THE RIDGE NEAR 
26N134W. A SOMEWHAT DIFFUSE TROUGH EXTENDS FROM THE CYCLONIC 
CIRCULATION SSW TO 14N140W. TO THE W OF CYCLONIC CIRCULATION...
A SHORTWAVE RIDGE WAS MOVING EWD AND FORCING THE CIRCULATION 
EWD IN TANDEM. WESTERLIES ALOFT DOMINATED MUCH OF THE AREA S OF 
THESE FEATURES...WITH A TROPICAL JET STREAM BRANCH EXTENDING 
FROM THE CENTRAL PACIFIC DEEP TROPICS NE THROUGH 13N140W TO 
14N130W TO 15N121W AND TO OVER WESTERN MEXICO NEAR 23N106W
...AND CONTINUED WELL NEWD TO ACROSS THE CENTRAL U.S. AHEAD OF
THE TROUGH. ACROSS THE DEEP TROPICS...ACTIVE CONVECTION ALONG 
THE ITCZ WAS MAINTAINING UPPER LEVEL RIDGING ALIGNED ROUGHLY
ALONG 7N WITH AN ASSOCIATED ANTICYCLONE NEAR 7N103W. WITH THIS
IN PLACE...AND TROUGHS PASSING JUST THE N EXPECT CONVECTION NEAR 
THE ITCZ TO REMAIN PRETTY ACTIVE W OF ABOUT 93W THROUGH THE NEXT
48 HRS.

OVER THE EASTERN PORTION OF THE AREA...A WEAK MID/UPPER LEVEL 
TROUGH EXTENDED FROM 18N106W TO 12N109W. THIS WAS HELPING TO 
SUSTAIN CONVECTION NEAR THE ITCZ BETWEEN 108W-112W IN ADDITION 
TO A SURFACE TROUGH ANALYZED FROM 4N118W TO 11N116W. ANOTHER 
WEAK MID/UPPER LEVEL TROUGH WAS OVER THE FAR EASTERN PORTION FROM
NEAR EL SALVADOR SW TO 12N93W TO NEAR 9N97W. DUE THE AN ABUNDANCE
OF MODERATE SUBSIDENCE AND ASSOCIATED DRY EVIDENT ON EITHER SIDE
OF THE TROUGH...ONLY ISOLATED SMALL SHOWERS AND TSTMS WERE NOTED 
WITHIN 45 NM OF THE SE MEXICAN COAST BETWEEN 94W AND THE BORDER 
OF GUATEMALA. THE TROUGH IS FORECAST TO MOVE E OF THE AREA THIS
AFTERNOON AND TONIGHT WHILE DAMPENING OUT.

ELSEWHERE AT THE SURFACE...A RIDGE STRETCHED NW TO SE THROUGH 
THE AREA FROM 30N130W TO 18N117W WITH THE PARENT HIGH CENTER OF 
1033 MB N OF THE AREA NEAR 36N136W. HIGH PRES COVERED THE AREA N 
OF 14N AND W OF 115W. THE PRES GRADIENT BETWEEN THE RIDGE AND 
LOWER PRES ASSOCIATED WITH THE ITCZ WAS MAINTAINING A LARGE AREA 
OF NE-E TRADES IN THE RANGE OF 20-25 KT FROM 6N TO 22N W OF 
122W. A TIGHT PRES GRADIENT BETWEEN THE AFOREMENTIONED HIGH PRES 
AND TROUGHING OVER THE SIERRA MADRE OCCIDENTALS WAS RESULTING IN 
NW TO N WINDS OF 20-25 KT N OF 22N E OF 122W WAS EVIDENT IN A 
HIGH RESOLUTION ASCAT PASS FROM AROUND 0445 UTC LAST NIGHT. THIS 
GRADIENT IS ALSO RESPONSIBLE FOR INCREASING NW WINDS TO 20-25 KT 
THROUGH THE GULF OF CALIFORNIA N OF 25N...WHERE SEAS ARE BUILDING
TO 6 FT AND GREATER. THESE WINDS ARE FORECAST TO BRIEFLY 
INCREASE TO 30 KT THIS AFTERNOON...THEN BACK DOWN TO 20-25 KT 
TONIGHT UNDER SOME EFFECTS OF NOCTURNAL/DIURNAL INDUCED 
FLUCTUATIONS. THE WINDS SHOULD THEN WEAKEN TO LESS THAN 20 KT BY 
THU AFTERNOON. A STRONG FRONTAL SYSTEM MOVING MOVING INTO THE NE 
WATERS N OF THE AREA THIS AFTERNOON INTO TONIGHT WILL ALLOW FOR 
THE ABOVE HIGH CENTER TO WEAKEN DISSIPATE...THEN BE REPLACED BY 
A STRONGER HIGH ON THU. THE RESULTANT TIGHTENING PRES GRADIENT 
WILL ACTIVATE A LARGE AREA OF TRADES OVER JUST ABOUT THE ENTIRE 
WESTERN HALF OF THE AREA N OF THE ITCZ.

OVERNIGHT SEAS STATE ANALYSIS PICK UP ON MAXIMUM VALUES OF 12-14 
FT ON THE FAR NE WATERS TO JUST N OF 30N. THIS IS IN VERY GOOD 
AGREEMENT WITH THE MAJORITY OF THE WAVEWATCH GUIDANCE AND LATEST 
NWW3 ENSEMBLE MAX SIGNIFICANT WAVE HEIGHTS. WAVE GUIDANCE IS
CONSISTENTLY PAINTING THE ENTIRE AREA W OF ABOUT 110W N OF 15N
...AND W OF 93W S OF 15N WITH SEAS IN THE RANGE OF 8-11 FT IN 
A NW SWELL. AT THE SAME TIME...IT APPEARS THAT LONG PERIOD SRN 
HEMISPHERIC SW SWELLS ARE MERGING WITH THE NW SWELLS OVER THE SRN
SECTION OF THE AREA...AND WILL CONTINUE TO DO SO THROUGH THE NEXT
48 HRS. PRESENT INDICATIONS ARE THAT SEAS THROUGHOUT THE AFFECTED
SWELL AREAS WILL SLOWLY SUBSIDE THROUGH THE END OF WEEK...HOWEVER
YET ANOTHER LARGE SWELL TRAIN PRODUCING SIGNIFICANT WAVE HEIGHTS 
UP TO POSSIBLY 14 FT IS FORECAST TO PROPAGATE S INTO THE FAR NE 
WATERS BEGINNING FRI MORNING AS AGREED BY ALL WAVEWATCH GUIDANCE.

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

$$
AGUIRRE