000
AXPZ20 KNHC 160918
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED JAN 16 2008

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 
0900 UTC.
 
...ITCZ...

ITCZ AXIS IS CENTERED ALONG 5N77W 8N90W 6N102W 8N120W 6N140W. NO 
SIGNIFICANT CONVECTION.

...DISCUSSION...

N OF 20N...
THE OMEGA BLOCK IS BREAKING DOWN AS EXPECTED AS A SIGNIFICANT 
DEEP TROUGH CONTINUES TO DIG SOUTHWARD OVER THE WESTERN UNITED 
STATES AND ESSENTIALLY ERODE THE BLOCKING RIDGE. ONE SHORTWAVE 
TROUGH IS LOCATED AT THE BASE OF THE LONGWAVE TROUGH OVER SOUTH 
TEXAS AND NE MEXICO ALONG 100W...AND IS TRIGGERING STRONG 
PRESSURE FALLS OVER THE GULF OF MEXICO. A SECOND SHORTWAVE 
TROUGH IS PLUNGING SOUTHWARD ON THE BACK SIDE OF THE TROUGH 
ACROSS SOUTHERN CALIFORNIA AND WILL ACT TO KEEP THE LARGE-SCALE 
TROUGH PLANTED ACROSS THE WESTERN UNITED STATES FOR A FEW DAYS. 
MODERATE/STRONG SUBSIDENCE WITHIN THE BASE OF THE TROUGH IS 
KEEPING SKIES MOSTLY CLEAR ACROSS NW MEXICO AND THE ADJACENT 
WATERS...ALTHOUGH THERE IS SOME LOW STRATUS/FOG DEVELOPING UP TO 
400 NM W OF BAJA CALIFORNIA N OF PUNTA EUGENIA DUE TO COOL 
UPWELLED WATERS. OVER THE NEXT FEW DAYS...STRONG HIGH PRES WILL 
BUILD ACROSS THE INTERMOUNTAIN WEST BEHIND A COLD FRONT WHICH 
WILL REACH NW MEXICO BY TONIGHT. SANTA ANA WINDS WILL BE ON THE 
INCREASE TODAY ACROSS SOUTHERN CALIFORNIA AND NW MEXICO...AND 
WINDS ARE EXPECTED TO REACH UP TO 30 KT OVER NORTHERN PARTS OF 
THE GULF OF CALIFORNIA BY TONIGHT WITH THE INITIAL SURGE.

ELSEWHERE...A CUT-OFF UPPER TROUGH EXTENDS SW OF BAJA CALIFORNIA 
FROM 24N114W TO 20N124W. THE UPPER RIDGE IS LOCATED ROUGHLY 
ALONG 130W AND THE DEEP-LAYERED CYCLONE IS NE OF THE HAWAIIAN 
ISLANDS NEAR 32N150W. THE SUBTROPICAL JET LIES ON THE SE 
PERIPHERY OF THE CYCLONE ENTERING INTO THE AREA WITH WINDS OF 85 
KT OR SO...AND ADVECTING HIGH-LEVEL CIRRUS EASTWARD TO 126W.

S OF 20N...
THE UPPER LEVEL PATTERN HAS CHANGED LITTLE OVER THE PAST 24 
HOURS. A BROAD UPPER TROUGH IS LOCATED ALONG 114W WITH 
SOUTHWESTERLY FLOW EXTENDING TO ITS E TOWARDS SE MEXICO AND 
CENTRAL AMERICA...AND WEST TO NORTHWESTERLY FLOW APPROACHING IT 
FROM THE WEST. WEAK UPPER DIFFLUENCE E OF THE TROUGH AXIS IS 
PRODUCING SCATTERED SHOWERS/TSTMS FROM 10N-15N BETWEEN 106W-112W 
BUT THE COVERAGE AND INTENSITY HAS DECREASED CONSIDERABLY FROM 
THIS TIME YESTERDAY. A WEAK SURFACE TROUGH IS LOCATED NEAR 115W 
AS WELL AND MAY BE ENHANCING THE LOW-LEVEL CONVERGENCE IN THE 
AREA.

$$
BERG