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AXPZ20 KNHC 182147
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU DEC 18 2014

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC.


...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS W FROM THE PACIFIC COAST OF COLOMBIA AT 06N77W TO 06N91W WHERE SCATTEROMETER WINDS INDICATE A TRANSITION TO AN ITCZ WHICH WIGGLES W BETWEEN 04-06N TO BEYOND 140W. SCATTERED MODERATE CONVECTION IS OBSERVED ALONG THE MONSOON TROUGH WITHIN 120 NM EITHER SIDE OF A LINE FROM 04.5N77W TO 07N86W. ISOLATED CLUSTERS OF MODERATE CONVECTION IS NOTED ELSEWHERE WITHIN 180 NM OF THE MONSOON TROUGH AND ITCZ AXIS.


...DISCUSSION...

AN UPPER LEVEL LONGWAVE TROUGH AND MOVED E OVER THE CENTRAL PORTION OF THE DISCUSSION AREA WITH ITS MEAN AXIS CURRENTLY EXTENDING S FROM 32N110W TO A BASE OVER THE DEEP TROPICS AT 10N138W. SHORTWAVE TROUGHS CONTINUE TO PASS THROUGH THE LONGWAVE PATTERN WITH THE MOST SIGNIFICANT TROUGH CURRENTLY MOVING E INTO THE FAR NW PORTION OF THE DISCUSSION AREA. SCATTERED MODERATE CONVECTION IS ENHANCED E OF THE UPPER TROUGH WITHIN 90 NM EITHER SIDE OF A LINE FROM 07N135W TO 11N121W TO 20N111W. A DENSE TROPICAL PLUME OF UPPER MOISTURE THAT ORIGINATED FROM ITCZ CONVECTION BETWEEN 130-170W...CONTINUES TO STREAM NE ACROSS THE DISCUSSION AREA WITHIN ABOUT 300 NM EITHER SIDE OF A LINE FROM 07N136W TO ACROSS NORTHERN MEXICO...EVENTUALLY TURNING E ACROSS THE NORTHERN GULF OF MEXICO. DEBRIS MOISTURE FROM THE PREVIOUSLY DESCRIBED CONVECTIVE CLUSTERS E OF THE UPPER TROUGH IS RE- ENFORCING THE PLUME.

AT THE LOW LEVELS LONG PERIOD NW SWELL CONTINUES TO MIX WITH LONG PERIOD SOUTHERLY SWELL ACROSS THE ENTIRE OPEN WATERS WATERS W OF 100W. A SURFACE RIDGE EXTENDS FROM 28N140W TO 15N98W WITH A COLD FRONT FORECAST TO PASS E ACROSS THE WATERS N OF THE RIDGE. ALTHOUGH EXPECTING ONLY A W-NW 10-15 KT WIND SHIFT ALONG THE FRONT...LARGE POST-FRONTAL NW SWELLS WILL DRIVE COMBINED SEAS UP TO 17 FT NEAR 30N138W ON FRI. THIS LONG PERIOD NW SWELL WILL ARRIVE ALONG THE PACIFIC COAST OF THE BAJA PENINSULA IN THE FORM OF 8-12 FT SEAS AS EARLY AS SAT EVENING...WITH 7-10 FT SEAS EXPECTED ALONG THE ENTIRE PACIFIC COAST OF THE BAJA PENINSULA BY EARLY SUN.

NE 15-20 KT TRADES ARE OBSERVED ACROSS THE TROPICS BETWEEN THE ITCZ AND THE RIDGE WITH AN AREA OF EMBEDDED 20-25 KT NE WINDS ACROSS THE WATERS FROM 10-15N W OF 135W. THE GRADIENT SHOULD CONTINUE TO TIGHTEN OVER THE NEXT SEVERAL DAYS WITH THE 20-25 KT CONDITIONS SPREADING BOTH NORTHWARD AND EASTWARD.

GULF OF TEHUANTEPEC...EXPECTING A MAX OF 10-15 KT NOCTURNAL DRAINAGE FLOW ACROSS THE GULF OF TEHUANTEPEC THROUGH TUE. MODEL GUIDANCE SUGGESTS THE THE NEXT GALE EVENT WILL OCCUR LATE TUE NIGHT.

GULF OF PAPAGAYO...NE 15-20 KT NOCTURNAL PULSES EXPECTED THROUGH EARLY SUN THEN 10-15 KT DRAINAGE EARLY NEXT WEEK.

GULF OF CALIFORNIA...10-15 KT NW WINDS ARE EXPECTED TO GRADUALLY INCREASE TO 15-20 KT LATE TONIGHT BY EARLY FRI...AND THEN CONTINUE THROUGH SUN NIGHT BEFORE DIMINISHING TO 15 KT ON MON.

$$ NELSON

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