000
AXPZ20 KNHC 172200
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU JAN 17 2008

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.
 
...ITCZ...
ITCZ AXIS IS CENTERED ALONG 5N78W 5N90W 6N100W 6N110W 7N122W 5N130W 
4N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 60 NM S 
OF AXIS BETWEEN 78W AND 84W.

...DISCUSSION...
A PRONOUNCED LONGWAVE TROUGH EXTENDS SW FROM THE SOUTHWEST CONUS 
ACROSS NORTHERN BAJA CALIFORNIA...THEN W TO 30N126W. AN EMBEDDED 
SHORTWAVE TROUGH IS SWINGING S ACROSS NORTHERN BAJA CALIFORNIA TO 
25N117W. AN UPPER ANTICYCLONE IS WELL N OF THE REGION NEAR 44N132W. 
NLY FLOW BETWEEN THE TROUGH AND THE HIGH IS CHANNELING HIGH LEVEL 
MOISTURE SWD ALONG THE WEST COAST INTO THE NE CORNER OF THE REGION.
BROAD MID LEVEL RIDGING W OF THE TROUGH ROUGHLY ALONG 130W. THE 
TROUGH WILL GRADUALLY SHIFT EWD OVER THE NEXT FEW DAYS AND FLATTEN 
AS THE BROAD SCALE FLOW BECOMES WLY OVER THE REGION. LITTLE IN THE 
WAY OF ANY DEEP CONVECTION IS OBSERVED OVER THE FAR ERN PART OF THE 
PACIFIC IN THE VICINITY OF THE TROUGH DUE TO THE SUBSIDENCE PRESENT 
N OF 21N E OF 120W. ITCZ CONVECTION IS EXPECTED TO REMAIN SUBDUED 
UNDER DRY AIR THAT COVERS NEARLY THE ENTIRE AREA ESE OF THE TROUGH. 
LIMITED CONVECTION IN ASSOCIATION WITH THE ITCZ BETWEEN 78W-84W IS 
DUE TO LOW LEVEL CONVERGENCE SUPPORTED BY ANTICYCLONIC FLOW ALOFT.

STRONG HIGH PRES CENTERED OVER THE WESTERN CONUS IN COMBINATION WITH 
LOW PRES OVER NORTHWEST MEXICO HAS PROMPTED A GALE WARNING FOR THE 
GULF OF CALIFORNIA N OF 28N...WHERE WINDS ARE FORECAST UP TO 40 KT 
THIS EVENING. ELSEWHERE ACROSS THE GULF OF CALIFORNIA WINDS WILL BE 
NW 20-25 KT...DECREASING TO 20 KT OR LESS IN 36 HRS.

SFC RIDGE EXTENDS FROM 32N133W SE TO 22N121W. HIGH PRES COVERS THE 
AREA N OF 20N AND W OF 110W. A WEAK SLOW MOVING SFC TROUGH S OF 10N 
ALONG 125W IS PRODUCING BROKEN LOW CLOUDS AND ISOLATED SHOWERS.

GULF OF PAPAGAYO GAP WINDS FLUCTUATING DIURNALLY AROUND 20 KT WILL 
LAST INTO EARLY NEXT WEEK. THE NEXT GALE EVENT IS EXPECTED TO BEGIN 
IN THE GULF OF TEHUANTEPEC LATE SAT DUE TO STRONG HIGH PRES BUILDING 
S OVER CENTRAL AND SOUTHEASTERN MEXICO...AND PERSIST THROUGH SUN.

$$
MUNDELL