000
AXPZ20 KNHC 291533
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU NOV 29 2007

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1515 UTC.
 
...ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N77W 6N95W 14N120W 9N130W 8N140W. 
SCATTERED MODERATE CONVECTION WITHIN 90 NM OF AXIS BETWEEN 
93W-106W. SCATTERED MODERATE/ISOLATED STRONG FROM 8N-18N BETWEEN 
107W-122W.

...DISCUSSION...

E OF 110W...
A STRONG MID-LEVEL HIGH IS CENTERED OVER THE S/CENTRAL GULF OF 
MEXICO WITH AN UPPER RIDGE AXIS EXTENDING FROM NORTHERN COLOMBIA 
NW TO THE TEXAS/MEXICO BORDER. DUE TO THE RIDGE...THE FLOW ALOFT 
E OF 100W IS PRIMARILY SOUTHERLY BUT A LACK OF MOISTURE S OF THE 
EQUATOR IS PRODUCING MAINLY DRY AIR NEAR CENTRAL AMERICA. 
SPORADIC DEEP CONVECTION IS OCCURRING ALONG THE ITCZ E OF 
110W...BUT THE LOW-LEVEL ENVIRONMENT N OF THE AXIS IS ALSO 
RATHER DRY. A MODEST GAP WIND EVENT IS OCCURRING OVER THE GULF 
OF TEHUANTEPEC AND GULF OF PAPAGAYO BUT BOTH ARE EXPECTED TO 
REMAIN BELOW GALE CRITERIA. ELSEWHERE...AN UPPER LEVEL SHORTWAVE 
TROUGH IS LOCATED ALONG 101W OVER CENTRAL MEXICO AND THE 
ADJACENT WATERS...PRODUCING ADDITIONAL SUBSIDENCE OVER THE AREA 
N OF 15N E OF 104W.

W OF 110W...
THE MAJOR WEATHER MAKER OVER THE SUBTROPICAL PACIFIC WATERS IS A 
LARGE CUT-OFF LOW CENTERED W OF BAJA CALIFORNIA NEAR 26N125W 
WHICH IS EXPECTED TO REMAIN NEARLY STATIONARY FOR ANOTHER 24 HRS 
OR SO...THEN LIFT NE AND BECOME ABSORBED BY A LARGER UPPER 
TROUGH OVER THE WESTERN UNITED STATES. STRONG UPPER DIFFLUENCE 
IS OCCURRING SE OF THE LOW WHERE PART OF THE FLOW TURNS NE INTO 
NW MEXICO AND THE OTHER PART TURNS SE PAST THE EQUATOR. THIS HAS 
CAUSED SURFACE PRESSURES TO LOWER IN THE AREA WITH A SURFACE 
TROUGH EXTENDING FROM 12N124W TO 20N118W TO 27N117W. MODEL 
GUIDANCE IS IN FAIRLY GOOD AGREEMENT THAT A SURFACE LOW WILL 
DEVELOP ALONG THE TROUGH WITHIN THE NEXT 24 HRS IN THE VICINITY 
OF 26N120W THEN LIFT NE INTO SOUTHERN CALIFORNIA AND ARIZONA BY 
SAT MORNING. THERE IS THE POTENTIAL FOR SIGNIFICANT RAINFALL 
OVER PARTS OF BAJA CALIFORNIA...SONORA...SINALOA...AND CHIHUAHUA 
THROUGH SAT DUE TO THE DEEP PLUME OF MOISTURE THAT WILL STREAM 
IN FROM THE SOUTH. THEREAFTER...THE LOW WILL LIKELY CONTRIBUTE 
TO A SIGNIFICANT WINTER STORM OVER PARTS OF THE ROCKIES AND 
CENTRAL PLAINS EARLY NEXT WEEK.

ELSEWHERE...MODERATE/STRONG SUBSIDENCE IS OCCURRING ON THE BACK 
SIDE OF THE CUT-OFF LOW WHERE THE FLOW IS CONVERGING INTO THE 
BASE OF THE TROUGH. THERE IS VERY LITTLE CLOUD COVER AT THE 
MOMENT AND THE TRADES ARE ACTUALLY EXPECTED TO WEAKEN OVER THE 
NEXT FEW DAYS AS LOW PRES DEVELOPS TO THE E AND BREAKS DOWN THE 
RIDGE.
  
$$
BERG