000
AXPZ20 KNHC 310413
TWDEP 

TROPICAL WEATHER DISCUSSION     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED JAN 31 2007

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0345 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 3N78W 4N90W 5N110W 4N120W 3N130W 
2N140W. SCATTERED STRONG CONVECTION IS WITHIN 60 NM EITHER SIDE 
OF THE AXIS BETWEEN 98W-100W.
    
...DISCUSSION...

SLIGHT REX BLOCK STILL IN PLACE OFF THE WRN U.S. COAST BUT THE 
UPPER HIGH OFF THE ALASKAN PANHANDLE AND AN UPPER LOW ABOUT 
300 NM WSW OF LOS ANGELES ARE BECOMING DISJOINTED FROM EACH 
OTHER. THE LOW IS BEING NUDGED SSE AS NLY FLOW AROUND THE UPPER
HIGH HIGH IMPACTS IT. THE LOW IS FORECAST TO EVENTUALLY MOVE MORE
E TOWARDS THE NRN PORTION OF BAJA CALIFORNIA IN ABOUT 24-36 HRS. 
FAST-MOVING ZONAL FLOW LIES S OF THE UPPER LOW WITH THE 
SUBTROPICAL JET CENTERED ALONG 25N/26N...AND MID/UPPER LEVEL 
MOISTURE/CLOUDINESS HAS MOVED INTO THE REGION FROM A LARGE AND 
COMPLEX SYSTEM N OF HAWAII. WIDELY SCATTERED EMBEDDED SHOWERS 
ARE POSSIBLE UNDERNEATH THESE CLOUDS. AT THE SURFACE...A WEAK
TROUGH...REFLECTION OF THE UPPER LEVEL LOW...EXTENDS ALONG 
THE SRN CALIFORNIA COAST SEWD TO ALONG NRN BAJA CALIFORNIA...
AND THEN SW THROUGH 28N117W 26N121W TO 26N130W. SCATTERED TO 
BROKEN LOW CLOUDS WITH WIDELY SCATTERED SHOWERS MOVING TOWARDS 
THE SRN CALIFORNIA COAST ARE NOTED WITHIN 75 NM EITHER SIDE OF 
THE TROUGH.

THE ZONAL FLOW PATTERN IS INCREASINGLY UNDERGOING SOME CHANGES
PARTICULARLY OVER THE WRN PORTION OF THE REGION AS THE UPPER 
LEVEL LOW MENTIONED IN ABOVE PARAGRAPH CARVES OUT A MID/UPPER 
LEVEL TROUGH ALONG 127W/128W S TO 8N. THE TROUGH WILL SWING EWD
TOWARDS NRN AND CENTRAL MEXICO OVER THE NEXT FEW DAYS. EXPECT
AN INCREASE OF CONVECTIVE ACTIVITY IN THE VICINITY OF THE
ITCZ E OF 125W IN ADVANCE OF THE TROUGH. AN AREA OF STRONG 
SUBSIDENCE IS LOCATED FROM 6N-18N W OF 117W. SCATTERED MODERATE 
SUBSIDENCE AND COVERS THE REMAINDER OF THE REGION W OF ABOUT 
108W WITH ITCZ EXHIBITING VERY MINIMAL CONVECTIVE ACTIVITY...BUT 
MORE THAN WAS HAS BEEN NOTICED OVER THE PAST SEVERAL DAYS.

A MID-LEVEL RIDGE EXTENDS FROM THE CARIBBEAN WSW ACROSS NICARAGUA
AND COSTA RICA TO NEAR 8N110W WITH THE BULK OF THE MID-LATITUDE 
FLOW RUNNING ACROSS MEXICO INTO THE GULF OF MEXICO. A WEAK UPPER 
TROUGH ROUGHLY ALONG 105W IS HELPING TO OFFSET SCATTERED STRONG 
CONVECTION ALONG THE ITCZ BETWEEN 98W-100W...BUT SHOULD NOT
LAST TOO LONG AS UPPER LEVEL ENVIRONMENT IS VERY DRY UNDER
SUBSIDENCE WHILE THE TROUGH DISSIPATES.

NE-E WINDS OF 20 KT OVER THE GULF OF PAPAGAYO WINDS WILL DIMINISH
TO LESS THAN 20 KT IN 48 HRS. N WINDS TO 20 KT OVER THE GULF OF 
PANAMA ARE EXPECTED TO DIMINISH IN 36 HRS.

$$
AGUIRRE