000 AXPZ20 KNHC 190847 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC THU NOV 19 2015 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0900 UTC. ...SPECIAL FEATURES... TROPICAL DEPRESSION TWENTY-ONE-E CENTERED NEAR 13.7N 106.1W AT 19/0900 UTC OR 330 NM SSW OF MANZANILLO MEXICO MOVING N AT 5 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 180 NM IN THE N QUADRANT. THE DEPRESSION IS FORECAST TO STRENGTHEN TO A TROPICAL STORM LATER TODAY. A SLOW NORTHWARD DRIFT WILL CONTINUE THIS MORNING...THEN IT IS FORECAST TO BEGIN TO MOVE NW BY 12-24 HOURS MOVING TO THE EAST OF CLARION ISLAND BY EARLY SUNDAY. SEE LATEST NHC FORECAST /ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS. GALE WARNING FOR GULF OF TEHUANTEPEC...HIGH PRES WILL BUILD BEHIND A COLD FRONT IN THE WESTERN GULF OF MEXICO N OF THE AREA WHICH WILL INDUCE ANOTHER ROUND OF FRESH TO NEAR GALE FORCE NORTHERLY WINDS IN THE GULF OF TEHUANTEPEC LATER TODAY...INCREASING TO MINIMAL GALE FORCE TONIGHT WITH SEAS TO 10 FT...AND DIMINISHING TO BELOW GALE FORCE LATER IN THE DAY ON FRIDAY. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM 11N86W TO 11N100W THEN RESUMES FROM 11N110W TO LOW PRES NEAR 09N117W TO LOW PRES NEAR 10N127W TO 07N135W. SCATTERED MODERATE CONVECTION 07N TO 10N BETWEEN 85W AND 100W. SCATTERED MODERATE WITHIN 75 NM N OF MONSOON TROUGH BETWEEN 118W AND 121W. SCATTERED MODERATE WITHIN 60 NM N QUADRANT OF LOW PRES NEAR 10N127W. ...DISCUSSION... N OF 15N E OF 120W...WEAK TROUGHING OVER NW MEXICO HAS DISSIPATED AS HIGH PRES WEST OF THE AREA HAS SHIFTED EAST. THIS HAS ALLOWED THE TIGHT PRES GRADIENT THAT WAS PREVIOUSLY OVER THE REGION TO WEAKEN...AND IN TURN ALLOWED STRONG WINDS OVER THE GULF OF CALIFORNIA AND OFF THE WEST COAST OF THE BAJA CALIFORNIA PENINSULA TO DIMINISH SLIGHTLY. AN ALTIMETER PASS FROM 02 UTC INDICATED SEAS TO NEAR 8 FT IN BOTH THE SOUTHERN GULF OF CALIFORNIA AND OFF BAJA CALIFORNIA SUR...BUT WAVE HEIGHT WILL CONTINUE TO SUBSIDE THROUGH THE MORNING. NW SWELL WITH WAVE HEIGHTS OF 8 TO 9 FT WILL PERSIST W OF 118W THROUGH THIS MORNING...THEN CONTRACT WESTWARD AS THE SWELL DECAYS. FARTHER SOUTH...CONVECTION IS PULSING ON THE NORTH SIDE OF DEVELOPING T.D. TWENTY-ONE E CENTERED NEAR 13.7N 106.1W. THIS TROPICAL DEPRESSION WILL DEVELOP INTO A TROPICAL STORM LATER TODAY AND MOVE TOWARD NW TOWARD CLARION ISLAND OVER THE NEXT 2 TO 3 DAYS. SEAS GREATER THAN 8 FT WILL FOLLOW THE PATH OF THE STORM WITHIN 270 NM OF THE CENTER THROUGH LATE THIS WEEK. S OF 15N E OF 110W...DEEP LAYER DRY AIR IS IN PLACE ACROSS MUCH OF THE AREA N OF 10N INFLUENCED BY A BROAD UPPER ANTICYCLONE CENTERED OVER SOUTHERN MEXICO...KEEPING OVERNIGHT CONVECTION MINIMAL OFF THE CENTRAL AMERICAN COAST NORTH OF COSTA RICA. SCATTERED CONVECTION PERSISTS S OF THE MONSOON TROUGH ALONG ROUGHLY 10N HOWEVER DUE TO CONVERGENCE OF MODERATE SW FLOW IN THE LOWER LEVELS AND WEAK UPPER DIVERGENCE ON THE SOUTHERN PERIPHERY OF THE MID/UPPER RIDGE. NO MAJOR CHANGES ARE EXPECTED OVER THE NEXT 2 TO 3 DAYS. LOOKING AHEAD...SOME UNCERTAINTY IN GLOBAL MODEL GUIDANCE WITH REGARD TO THE DEVELOPMENT OF LOW PRES ALONG THE MONSOON TROUGH EAST OF COSTA RICA BY SAT. THE GFS IS AN OUTLIER SHOWING AGGRESSIVE DEVELOPMENT. ELSEWHERE...SCATTEROMETER DATA CONTINUES TO SHOW STRONG TRADE WINDS OVER MUCH OF THE AREA N OF 11N BETWEEN RIDGING ASSOCIATED WITH THE 1030 MB HIGH NEAR 35N135W AND LOWER PRES ALONG THE MONSOON TROUGH/ITCZ. VARIOUS ALTIMETER DATA CONTINUE TO SHOW SEAS AS HIGH AS 12 FT IN THE AREA OF THE STRONG TRADE WINDS... HELPED IN PART PRIMARILY BY LONG PERIOD NW SWELL PREVAILING ACROSS MUCH OF THE REGION. THIS IS PRODUCING AN UNUSUALLY LARGE AREA OF CONFUSED SEAS OF 8 FT AND GREATER...ROUGHLY N OF 05N. THE RIDGE WILL GRADUALLY WEAKEN THROUGH THE REMAINDER OF THE WEEK AND ALLOW THE TRADE WINDS TO DIMINISH ACCORDINGLY. WINDS AND SEAS WILL SUBSIDE...BUT REMAIN 8 FT OR GREATER ACROSS MUCH OF THE AREA THROUGH LATE IN THE WEEK. $$ CHRISTENSEN