000
AXPZ20 KNHC 250929
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE MAY 25 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 
0730 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ALONG 11N86W TO 
09N104W TO 08N115W TO 09N129W TO 07N140W. SCATTERED MODERATE 
CONVECTION LIES WITHIN 75 NM EITHER SIDE OF THE ITCZ AXIS 
BETWEEN 97W AND 104W. A TROUGH IS EMBEDDED IN THE ITCZ ALONG 85W 
FROM 02N TO 11N. SCATTERED MODERATE CONVECTION IS NOTED WITHIN 
75 NM E AND 180 NM W OF THE TROUGH AXIS N OF 07N.

...DISCUSSION...
A FLAT...BROAD UPPER LEVEL TROUGH COVERS THE FAR N PORTION OF 
THE DISCUSSION AREA GENERALLY ALONG A LINE FROM 24N140W TO 
28N110W WITH A 300 NM WIDE RIBBON OF DRY AIR CUTTING THROUGH THE 
BASE OF THE TROUGH. THE SOUTHERN EDGE OF THE DRY AIR IS SITUATED 
TO THE N OF A 70-90 KT SUBTROPICAL JET STREAM WHICH ENTERS THE 
AREA NEAR 20N140W AND CONTINUES ENE THROUGH 21N120W...THE 
SOUTHERN TIP OF BAJA CALIFORNIA AND INTO MEXICO. THE JET IS 
ADVECTING HIGH LEVEL MOISTURE FROM ITCZ CONVECTION FROM AROUND 
130N NORTHEASTWARD INTO CENTRAL MEXICO.   

AN UPPER LEVEL RIDGE EXTENDS FROM AN ANTICYCLONIC CIRCULATION 
NEAR 12N118W TO THE GULF OF TEHAUNTEPEC. UPPER LEVEL DIFFLUENT 
FLOW TO THE SOUTH AWAY FROM THE RIDGE AXIS IS ENHANCING 
CONVECTION ALONG THE ITCZ FROM 97W-104W. DIFFLUENCE ALOFT CAN 
ALSO BE FOUND BETWEEN THE E EDGE OF THE RIDGE AXIS AND AN UPPER 
TROUGH STRETCHING FROM THE SW N ATLC THROUGH THE 
HONDURAS/NICARAGUA BORDER S TO NEAR THE GALAPAGOS ISLANDS. A LOW 
TO MID LEVEL CYCLONIC GYRE HAS POOLED MOISTURE IN THIS REGION 
AND MODERATE TO STRONG CONVECTION CAN CURRENTLY BE FOUND WITHIN 
120 NM OF THE COAST BETWEEN THE GULFS OF PAPAGAYO AND 
TEHUANTEPEC. A SURFACE TROUGH ASSOCIATED WITH THE GYRE LIES 
ALONG 85N N OF 02N TO THE GULF OF PAPAGAYO. THE 0304 AND 0446 
UTC ASCAT PASSES SHOW 20-25 KT INFLOW INTO THIS BROAD 
CIRCULATION IN THE AREA FROM 04N-10N BETWEEN THE TROUGH AND 
105W. MORE RECENT SURFACE OBSERVATIONS AND CLOUD MOTION 
SUGGEST A BROAD LOW PRESSURE AREA MAY BE DEVELOPING ON THE NORTH 
EDGE OF THIS TROUGH. REGARDLESS OF LOW DEVELOPMENT...THIS 
PORTION OF CENTRAL AMERICA WILL CONTINUE TO SEE HEAVY RAINFALL 
OVER THE NEXT FEW DAYS.

SURFACE RIDGE COVERS THE AREA N OF 14N W OF 110W. THE RIDGE IS 
PRODUCING A TIGHT ENOUGH PRES GRADIENT TO SUPPORT NE TO E 20-25 
KT WINDS IN AN AREA FROM 10N TO 23N W OF 125W. THE GRADIENT 
BETWEEN THE SAME RIDGE AND LOWER PRES OVER MEXICO IS PRODUCING 
20-25 KT NW WINDS ALONG THE COAST OF BAJA CALIFORNIA...WITH 
SHIPS A8FZ6 NEAR 26N118W AND ZQCP3 NEAR 26N117W REPORTING 23-24 
KT IN 12 FT SEAS. THESE WINDS WILL BECOME CONFINED E OF 118W TO 
THE BAJA CALIFORNIA COAST AS THE RIDGE WEAKENS. THE 0450 UTC 
ASCAT PASS ALSO SUPPORTED WINDS TO 20 KT IN THE GULF OF 
CALIFORNIA N OF 25N AND OFFSHORE OF CABO CORRIENTES. WINDS IN 
THE GULF ARE EXPECTED TO DIMINISH BELOW 20 KT THIS MORNING WHILE 
THOSE OFFSHORE OF CENTRAL MEXICO SHOULD SHIFT S AS THE RIDGE 
AXIS TO THE W IS FORCED SOUTHWARD BY AN APPROACHING COLD FRONT 
TUE. THIS COLD FRONT IS EXPECTED TO REACH N WATERS WITH LITTLE 
FANFARE OVERNIGHT TUE NIGHT WITH THE MAIN IMPACT BEING A NEW 
SURGE OF NW SWELL WITH SIGNIFICANT WAVE HEIGHTS TO 8 FT IN NE 
WATERS WED.

ANOTHER TRAIN OF LONG PERIOD...17-18 SECOND...SWELLS WITH DEEP 
WATER WAVE HEIGHTS OF 7-9 FT IS CROSSING THE EQUATOR AND IS 
EXPECTED TO IMPACT THE COAST OF CENTRAL AMERICA AND MEXICO 
OVERNIGHT TUE NIGHT AND SPREAD INTO THE SRN GULF OF CALIFORNIA 
AND BAJA CALIFORNIA WED.

$$
SCHAUER/COBB