000
AXPZ20 KNHC 062157
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI NOV 06 2009

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 
2145 UTC.

...TROPICAL LOWS...

.LOW PRES IS CENTERED NEAR 12N92W ESTIMATED AT 1008 MB AND IS 
NEARLY STATIONARY. THE SYSTEM IS ENCOUNTERING SOUTHWESTERLY WIND 
SHEAR AND DRY AIR ENTRAINMENT FROM A LARGE MID TO UPPER TROUGH 
IMMEDIATELY TO ITS W. CURRENTLY SCATTERED MODERATE AND ISOLATED 
STRONG CONVECTION IS NOTED WITHIN 30 NM OF 12.5N92W.

.LOW PRES IS CENTERED NEAR 14N115.5W ESTIMATED AT 1010 MB. THE 
SURFACE LOW IS UNDER AN UPPER ANTICYCLONE AND THE ASSOCIATED 
UPPER DIFFLUENCE HAS BEEN ENHANCING CONVECTION BUT OVERALL 
CONVECTION HAS BEEN DECREASING THE PAST FEW HOURS. CURRENTLY 
SCATTERED MODERATE CONVECTION IS NOTED WITHIN 30 NM OF 13N116W.

...ITCZ...

THE ITCZ AXIS EXTENDS ALONG 13N88W TO 07N99W TO 13N115W TO 
06N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED 
WITHIN 75 NM EITHER SIDE OF A LINE FROM 07N104W TO 11N110W. 

...DISCUSSION...

AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR 13N117W WITH A SHORT 
WAVE RIDGE SHIFTING NE AND NOW CRESTING NEAR THE SOUTHERN TIP OF 
THE BAJA PENINSULA. A TROPICAL RIDGE EXTENDS SW FROM THE 
ANTICYCLONE TO A SHARP CREST AT 12N129W WITH ANOTHER RIDGE 
EXTENDING SE FROM THE ANTICYCLONIC CENTER TO 05N98W. UPPER LEVEL 
DIFFLUENCE ENHANCED ITCZ CONVECTION BETWEEN 130W AND 137W WITH 
THE RESULTANT DEBRIS MOISTURE ADVECTED NE ALONG THE W PERIPHERY 
OF THIS TROPICAL RIDGE...ROUGHLY WITHIN 120 NM EITHER SIDE OF 
LINE 09N135W TO 18N114W. DEBRIS MOISTURE FROM EARLIER CONVECTION 
NEAR A SURFACE LOW UNDER THE UPPER ANTICYCLONIC CENTER... 
DESCRIBED ABOVE...REMAINS WITHIN 150 NM OF 14N115W. UPPER 
DIFFLUENCE IS ALSO ENHANCING CONVECTION ALONG THE ITCZ BETWEEN 
103W AND 112W WITH THE DEBRIS MOISTURE SPREADING S BUT 
EVAPORATING ALONG 03N.

AN UPPER RIDGE IS NOW AMPLIFYING NE INTO THE DISCUSSION AREA 
ALONG 27N140W TO 30N126W. AN UPPER CYCLONE IS NEAR 29N118W WITH 
A TROUGH EXTENDING SW TO 22N127W. DENSE UPPER MOISTURE IS 
OBSERVED OVER THE NE SEMICIRCLE OF THIS CYCLONE AND IS SPREADING 
NE ACROSS SOUTHERN CALIFORNIA AND NEW MEXICO. ELSEWHERE THE 
UPPER LEVELS APPEAR DRY N OF 20N W OF 120W. 

AN UPPER TROUGH EXTENDS S ALONG EASTERN OLD MEXICO INTO A SMALL 
MID TO UPPER CYCLONE AT 19N95W WITH THE TROUGH CONTINUING S TO A 
BASE OVER THE DEEP TROPICS AT 08N93W. THE CYCLONE APPEARS TO BE 
DEEPENING WITH A SURFACE LOW FORMING OVER THE SW BAY OF 
CAMPECHE. ISOLATED CONVECTION IS SLIGHTLY ENHANCED ALONG THE 
ITCZ JUST E OF THIS TROUGH...BETWEEN 92W AND 100W WITH MOST OF 
THE DEBRIS MOISTURE EVAPORATING QUICKLY AS UPPER DRY AIR IS 
SWEEPING S ACROSS OLD MEXICO AND OVER THE TROPICAL PACIFIC N OF 
10N BETWEEN 96W AND 108W. 

AN UPPER ANTICYCLONE IS OVER THE CENTRAL CARIBBEAN NEAR 14N74W 
WITH A RIDGE EXTENDING W TO NEAR 10N87W. SOME CONVECTION WAS 
ENHANCED ALONG THE PACIFIC COAST OF COLOMBIA BUT IS DISSIPATING 
AND THE DEBRIS MOISTURE IS SPREADING W AND NW ALONG THE UPPER 
RIDGE.    

AT THE LOW LEVELS A RIDGE IS BRIDGING SEVERAL FRONTAL TROUGHS 
OVER THE NW WATERS AND CRESTING NEAR 15N110W. ALTHOUGH 
ASSOCIATED WINDS ARE ONLY 15-20 KT THE FRONTS ARE ACCOMPANIED BY 
NW SWELLS THAT WILL CONTINUE TO BUILD TO NEAR 18 FT LATE SAT 
ALONG 30N BETWEEN 125W AND 135W.

GAP WINDS...
GALE FORCE WINDS ARE EXPECTED TO CONTINUE THROUGH THE GULF OF 
TEHUANTEPEC TONIGHT DIMINISHING BELOW GALE AFTER SUNRISE SAT 
MORNING. UNCERTAINTY CONTINUES IN THE FORECAST AS LOW PRES MAY 
BE DEVELOPING N OF THE AREA IN THE BAY OF CAMPECHE...THE 
PERSISTENT LOW PRES NEAR 12N92W MAY DRIFT N...AND TROPICAL 
DEPRESSION IDA IS NOW MOVING BACK OVER WATER AND IS FORECAST TO 
MOVE NORTHWARD AND STRENGTHEN. DEPENDING ON THE ORIENTATION OF 
THE LOW PRES CENTERS N OF THE AREA...ANOTHER N SURGE MAY OCCUR 
IN THE GULF OF TEHUANTEPEC OR THE LOW POSITIONS MAY ACTUALLY 
IMPEDE THE N FLOW THROUGH THE ISTHMUS OF TEHUANTEPEC.

$$
NELSON