000 AXPZ20 KNHC 130957 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC WED NOV 13 2013 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 0945 UTC. ...SPECIAL FEATURE... GULF OF TEHUANTEPEC...RECENT SCATTEROMETER PASSES DETECTED 30-40 KT WINDS N OF THE AREA ALONG THE MEXICAN/GULF OF MEXICO COAST NEAR 22N97W...AND MINIMAL GALE FORCE WINDS IN THE GULF OF TEHUANTEPEC. THE MOST RECENT PASS DETECTED MINIMAL GALE GALES ALONG CLIMATOLOGICAL WESTERN EDGE OF THE STRONGEST FLOW SUPPORTING THAT STRONGER N WINDS ARE LIKELY IN THE CENTER OF THE SWATH. ACTED THESE STRONG WINDS N OF THE AREA SUPPORTS THE FORECAST FOR STORM FORCE WINDS IN...AND JUST DOWNSTREAM OF... THE GULF OF TEHUANTEPEC BY LATE THIS AFTERNOON. THE MINIMAL STORM FORCE WINDS SHOULD PERSIST THROUGH SUNRISE ON THU THEN QUICKLY BEGIN TO DIMINISH WITH THE FINAL SURGE TO MINIMAL GALE FORCE DURING THE MAXIMUM DRAINAGE AROUND SUNRISE ON FRI. THE NORTHERLY WINDS SHOULD END LATE SAT. WAVE WATCH GUIDANCE NOT AS AGGRESSIVE WITH THE MAXIMUM SEAS HEIGHTS...THUS HAVE LOWERED THE MAX TO 20 FT AROUND SUNRISE ON THU. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS W-SW ACROSS THE SW CARIBBEAN FROM THE NW COAST OF COLOMBIA AT 10N75W TO ACROSS NORTHERN PANAMA AND SOUTHERN COSTA RICA TO THE PACIFIC COAST OF COSTA RICA AT 09N84W...THEN CONTINUES W TO 09.5N92W...THEN DIPS SW THROUGH AN EMBEDDED 1008 MB LOW PRESSURE AT 07.5N99W...THEN NW TO 09N105W WHERE SCATTEROMETER WINDS INDICATE A TRANSITION TO AN ITCZ AXIS. THE ITCZ DIPS S TO 08N114W..THEN NW TO 10N130W... THEN SW TO BEYOND 08N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED ALONG THE PACIFIC COAST OF PANAMA AND COSTA RICA WITHIN 15 NM OF LINE FROM 07N78W TO 07N83W. SIMILAR CONVECTION IS NOTED N OF THE MONSOON TROUGH WITHIN 15 NM EITHER SIDE OF A LINE FROM 16N98W TO 12N102W...AND ALSO S OF THE MONSOON TROUGH WITHIN 15 NM OF 05.5N81.5W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED ALONG THE MONSOON TROUGH AND ITCZ WITHIN 90 NM EITHER SIDE OF A LINE FROM 99N93W TO 09N115W TO 10N138W...AND WITHIN 15 NM OF LINE FROM 07.5N113W TO 06N118W. BROKEN TO OVERCAST LOW/MID LEVEL CLOUDS...WITH ONLY EMBEDDED WEAK SHOWERS...IS NOTED ACROSS THE DEEP TROPICS ELSEWHERE FROM 10N TO THE EQUATOR FROM THE S AMERICAN COAST WESTWARD TO ALONG 110W...AND FROM 04-10N BETWEEN 110-140W. ...DISCUSSION... THE UPPER PATTERN HAS CHANGED SIGNIFICANTLY OVER THE PAST 24 HOURS. A LONGWAVE UPPER RIDGE STILL DOMINATES WESTERN N AMERICA...BUT NOW ORIGINATES FROM A LARGE UPPER ANTICYCLONE OVER THE TROPICAL PACIFIC AT 13N135W...WITH ITS RIDGE AXIS EXTENDING NE THROUGH 32N134W. THE ASSOCIATED ANTICYCLONIC ENVELOPE COVERS THE WESTERN PORTION OF THE DISCUSSION AREA...TO THE N OF 07N BETWEEN 117-140W. DENSE UPPER MOISTURE...ORIGINATING W OF THE AREA...IS STREAMING NE IN THE STRONG UPPER SOUTHWESTERLY FLOW ALONG THE WESTERN PERIPHERY OF THE RIDGE...ROUGHLY WITHIN 270 NM EITHER SIDE OF A LINE FROM 25N140W TO 31N128W. THEN SOME OF THE MOISTURE THINS A LITTLE AS IT CROSSES THE RIDGE AXIS AND RETURNS BACK SE OVER THE DISCUSSION AREA TO THE N OF 22N BETWEEN 115- 125W. A BAND OF DENSE UPPER MOISTURE IS E OF THE UPPER RIDGE AXIS...AND IS RACING SE ACROSS ARIZONA AND THE BAJA CALIFORNIA PENINSULA AND GULF OF CALIFORNIA ALL TO THE N OF 27N. UPPER DIFFLUENCE ALONG THE SOUTHERN PERIPHERY OF THIS LARGE ANTICYCLONE IS ENHANCING CONVECTION ALONG THE ITCZ AS PREVIOUSLY DESCRIBED...WITH THE DEBRIS MOISTURE ADVECTED S TO THE EQUATOR NEAR 130W. A LONGWAVE UPPER TROUGH IS OVER EASTERN N-AMERICA...AND CONTINUES SW OVER THE DISCUSSION AREA FROM OVER TEXAS AT 31N97W TO ACROSS NORTHERN OLD MEXICO THROUGH AN ILL-DEFINED UPPER CYCLONE AT 27N106W...WITH THE TROUGH THEN CONTINUING SW THROUGH ANOTHER UPPER CYCLONE OVER THE SOUTHERN TIP OF THE BAJA CALIFORNIA PENINSULA...WITH THE TROUGH CONTINUING SW TO 12N115W...THEN S-SE TERMINATING IN AN UPPER CYCLONE OVER THE DEEP TROPICAL PACIFIC AT 04N117W. THIS UPPER TROUGH EFFECTIVELY SEPARATES THE UPPER ANTICYCLONIC FLOW OVER THE DISCUSSION AREA. DRY UPPER AIR IS INDICATED N OF 21N WITHIN 240 NM W OF THIS TROUGH AXIS...AND WITHIN ABOUT 1200 NM W OF THE TROUGH AXIS FROM 11-20N MOSTLY DUE TO UPPER ANTICYCLONIC FLOW PREVIOUSLY MENTIONED. AN UPPER ANTICYCLONE HAS SHIFTED E TO OVER HISPANIOLA WITH AN UPPER RIDGE EXTENDING SW ACROSS CENTRAL AMERICA TO A SHARP CREST OVER THE DEEP TROPICAL PACIFIC AT 10N111W. UPPER DIFFLUENCE ALONG THE SOUTHERN PERIPHERY OF THIS RIDGE IS ENHANCING CONVECTION ALONG THE LOWER LEVEL MONSOON TROUGH AND ITCZ... BETWEEN 92W-111W...AS WELL AS AFTERNOON PEAK-HEATING CONVECTION OVER THE SW CARIBBEAN AND OVER INTERIOR CENTRAL AMERICA. THE DEBRIS MOISTURE FROM ALL OF THIS CONVECTION IS ADVECTED NE ACROSS THE TROPICAL PACIFIC WITHIN 240 NM EITHER SIDE OF A LINE FROM 10N110W TO 20N100W WHERE THE MOISTURE THICKENS INTO A DENSE PLUME ADVECTED E ACROSS THE ENTIRE GULF OF MEXICO AND FLORIDA ALL AHEAD OF A VIGOROUS SHORTWAVE TROUGH PROGRESSING SE. WESTERN BAJA CALIFORNIA PENINSULA...NW 15-20 KT WINDS WITH SEAS 3-6 FT...PRIMARILY IN MIXING LONG PERIOD NW AND CROSS EQUATORIAL S SWELL...ARE CURRENTLY OBSERVED ACROSS THESE PACIFIC COASTAL WATERS TO THE N OF 27N...BUT SHOULD DIMINISH TO 10-15 KT EARLY THIS MORNING. THE GRADIENT WILL FURTHER RELAX TODAY SUPPORTING ONLY 5-10 KT BY SUNSET TODAY...AND CONTINUING THROUGH LATE THU. THESE LIGHT WINDS WILL BACK TO THE SW-W AT 10 KT ON FRI NIGHT INTO EARLY SAT...AHEAD OF A COLD FRONT MOVING ACROSS THE PACIFIC WATERS N OF 24N BETWEEN 113-120W ON SAT...FOLLOWED BY W-NW WINDS AT 15-20 KT...WITH SEAS BUILDING 6-9 FT LATE FRI NIGHT...AND CONTINUING THROUGH LATE SAT. EXPECT NW WINDS AT 10 KT/SEAS 3-5 FT ALONG THE ENTIRE PACIFIC COAST OF THE BAJA PENINSULA ON SUN...THEN INCREASING TO 10-15 KT ON MON. GULF OF CALIFORNIA...NW WINDS CURRENTLY AT 15-25 OVER THE NORTHERN GULF WATERS WILL QUICKLY DIMINISH TO 5-10 KT TODAY... WITH THESE CONDITIONS SPREADING S ACROSS THE ENTIRE GULF TONIGHT. THESE LIGHT WINDS WILL BECOME SOUTHERLY AT 10-15 KT ON FRI...EXCEPT 20-25 KT OVER THE FAR NORTHERN GULF WATERS IN ADVANCE OF A COLD FRONT ARRIVING LATE SAT. LIGHT NORTHERLY WINDS EXPECTED THROUGHOUT THE GULF WATERS LATE SUN INTO MON. GULF OF PAPAGAYO...NE WINDS ARE EXPECTED TO SURGE ACROSS THE GULF OF PAPAGAYO AT 15-20 KT WITH SEAS TO 4-6 FT THROUGH SUNRISE TODAY. THEREAFTER...NE 5-10 KT WINDS EXPECTED...EXCEPT INCREASING BRIEFLY TO 15-20 KT LATE EACH NIGHT THROUGH SUNRISE EACH MORNING...WITH THIS PATTERN CONTINUING THROUGH THE UPCOMING WEEKEND. ELSEWHERE AT THE SURFACE...A SURFACE RIDGE IS STRENGTHENING ACROSS THE DISCUSSION AREA WITH NE TRADES ALREADY INCREASING TO 15-25 KT/SEAS 6-9 FT ACROSS THE TROPICS FROM 10-20N BETWEEN 115- 140W. NORTHERLY 15-20 KT WINDS/SEAS 7-10 FT WILL COVER THE ENTIRE WATERS S OF 28N W OF 120W ON THU...WITH N WINDS AT 20-25 KT TO THE N OF 28N BETWEEN 120-130W...WITH ASSOCIATED SEAS BUILDING 9-13 FT. THE GRADIENT WILL BEGIN TO RELAX ON FRI NIGHT WITH LIGHT N WINDS ACROSS THE ENTIRE AREA N OF 20N W OF 108W ON SAT NIGHT. $$ NELSON