000 AXPZ20 KNHC 090334 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC TUE DEC 09 2008 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0300 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 5N78W 5N90W 7N100W 7N110W 09N120W 10N130W 9N140W. SCATTERED STRONG CONVECTION IS WITHIN 30 NM OF THE AXIS BETWEEN 109W-111W...AND BETWEEN 130W-135W. ...DISCUSSION... A PERSISTENT MID/UPPER LEVEL CYCLONIC CIRCULATION...ABOUT 5 DEG IN DIAMETER MOVING N 10 KT...IS NEAR 22N139W WITH A TROUGH EXTENDING TO 12N140W. A JET STREAM BRANCH WITH MAXIMUM WINDS OF 60-100 KT ENTERS THE AREA AT 11N140W ROUNDING THE BASE OF THE TROUGH...THEN STRETCHES NE TO 12N130W TO 25N127W AND E TO 28N121W WHERE IT CONTINUES EASTWARD TOWARDS NORTHERN BAJA CALIFORNIA TO ACROSS NORTHERN MEXICO AND NE ACROSS THE CENTRAL U.S. MARKING THE SOUTHERN PORTION OF A LONGWAVE TROUGH THAT COVERS MUCH OF THE WESTERN U.S. THE FAR SW PORTION OF THE TROUGH EXTENDS SW TO A COL REGION NEAR 32N126W...AND SW TO THE MID/UPPER LEVEL CYCLONIC CIRCULATION NEAR 22N139W. ANOTHER BRANCH OF THE JET STREAM SPLITS OFF THE FIRST ONE NEAR 18N128W AND DIVES SE THROUGH 17N118W TO 14N110W TO 5N106W. AT THE SURFACE ...A WEAKENING TROUGH ASSOCIATED WITH THE MID/UPPER LEVEL CYCLONIC CIRCULATION IS ANALYZED ALONG 140W FROM 21N TO 25N. THE INTERACTION BETWEEN THE TROUGH AND HIGH PRES TO THE N HAS TIGHTEN THE PRES GRADIENT FROM 19N TO 25N BETWEEN 122W AND 125W WHERE NE-E 20 TO 25 KT WINDS ARE BEING OBSERVED. THESE WINDS ARE FORECAST TO DIMINISH TO 20 KT IN ABOUT 24 HOURS UNTIL THE TROUGH MOVES W OF THE AREA TONIGHT. AN AREA OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NOTED FROM 16N TO 20N BETWEEN 131W AND 136W. A SURFACE RIDGE AXIS ENTERS THE DISCUSSION AREA THROUGH 32N129W AND EXTENDS THROUGH 25N120W TO 20N109W. HIGH PRES COVERS THE AREA N OF 19N W OF 110W. TO THE E OF THE ABOVE MENTIONED MID/UPPER CYCLONIC CIRCULATION AND TROUGH....MID/UPPER LEVEL RIDGING COVERS THE S AN SE OF THE MID/UPPER LEVEL TROUGH TO 13N BETWEEN 98W-124W...WITH THE EXCEPTION N OF A SHORTWAVE TROUGH THAT LIES FROM 18N127W TO 15N122W TO 10N116W. THIS TROUGH MARKS THE POINT AT WHICH THE JET STREAM ALSO BRANCHES TO THE SE ALONG 19N114W TO 10N106W. A ZONE OF UPPER LEVEL DIFFLUENCE CONTINUES TO ENHANCE A GROWING AREA OF CLOUDS WITH MAINLY MODERATE RAIN PATCHES WITH EMBEDDED SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM ALONG AND JUST N OF THE ITCZ BETWEEN 121W-129W N TO ABOUT 24N. LATEST SATELLITE IMAGERY CONTINUES TO SHOW AMPLE MID AND UPPER LEVEL SUB-TROPICAL MOISTURE IN THE FORM OF MIDDLE AND HIGH BROKEN TO OVERCAST CLOUDS RELATED THIS AREA OF PRECIPITATION STREAMING NORTHEASTWARD IN THE STRONG SW AND W ASSOCIATED WITH THE JET STREAM EASTWARD TOWARDS MUCH OF MEXICO...INCLUDING BAJA CALIFORNIA S OF 28N. AT THE SURFACE...A WEAK TROUGH IS ANALYZED ALONG 136W FROM 9N-13N. ISOLATED SHOWERS AND WEAK TSTMS ARE WITHIN 60 NM E OF THE TROUGH FROM 11N-13N. A WEAK 1010 MB LOW IS NOW IDENTIFIED NEAR 11N129W WITH A TROUGH NE TO 16N126W. THIS FEATURE IS EXPECTED TO DRIFT WNW DURING THE NEXT 24-48 HOURS BEFORE BECOMING DIFFUSED. HOWEVER...THE INTERACTION BETWEEN THE TROUGH AND HIGH PRES TO THE N CONTINUES TO TIGHTEN THE PRES GRADIENT FROM 12N TO 19N BETWEEN 118W-135W WHERE NE-E WINDS OF 20 TO 25 KT ARE OCCURRING. THESE WINDS ARE FORECAST TO EXPAND OUTWARD TO THE NE OF THE LOW FORECAST TO BE NEAR 14N1209 IN 24 HOURS...AND NEAR 15N130W AT 48 HOURS. ELSEWHERE FROM ABOUT 17N-27N W OF 128W TRADES ARE EXPECTED TO BE NE-E WINDS TO 20 KT THROUGH AT LEAST THE NEXT 48 HOURS. MODERATE SUBSIDENCE WITH ASSOCIATED DRY STABLE CONDITIONS HAS BEEN USHERED INTO THE FAR WESTERN PORTION OF THE REGION AS NORTHERLY W OF 140W BECOMES WESTERLY TO THE S AND SW OF THE MID/UPPER LEVEL CIRCULATION. THE CURRENT PATTERN WILL BEGIN TO CHANGE BY THU AS THE MID/UPPER LEVEL CYCLONIC CIRCULATION BEGINS TO LIFT NE TOWARDS THE FAR NORTHERN PORTION OF THE AREA WITH RIDGING AT ALL LEVELS PREDOMINATELY COVERING JUST ABOUT THE ENTIRE AREA. GAP WINDS...GULF OF PAPAGAYO NE 20 KT WINDS ARE EXPECTED TO DIMINISH IN ABOUT 24-36 HOURS. GULF OF TEHUANTEPEC N-NE 20 KT WINDS ARE FORECAST TO DIMINISH TO LESS THAN 20 KT SHORTLY. LATEST NWP MODEL GUIDANCE INDICATES THAT WINDS WILL SUBSTANTIALLY INCREASE IN THE GULF BEGINNING WED NIGHT SIGNIFYING THE ONSET OF THE NEXT GALE EVENT AS STRONG HIGH PRES SURGES SWD THROUGH CENTRAL AND SOUTHERN MEXICO BEHIND THE NEXT STRONG COLD FRONT EXPECTED TO PUSH OFF THE TEXAS COAST AND INTO THE WESTERN GULF OF MEXICO TUE NIGHT. $$ AGUIRRE