000
AXPZ20 KNHC 210316 AAA
TWDEP 

TROPICAL WEATHER DISCUSSION...CORRECTED
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU DEC 19 2013

CORRECTED 2ND PARAGRAPH UNDER DISCUSSION 

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... 

MONSOON TROUGH AXIS EXTENDS FROM LOW PRES NEAR 07N79W TO 09N86W 
TO 07N91W...WHERE IT TRANSITIONS TO THE ITCZ TO 06N102W TO 
09N115W TO 08N125W TO 08N140W. SCATTERED MODERATE CONVECTION IS  
WITHIN 120 NM N OF THE ITCZ BETWEEN 124W-127W...AND WITHIN 60 NM 
S OF THE ITCZ BETWEEN 136W-138W. 

...DISCUSSION... 

A RATHER VIGOROUS UPPER LOW IS MOVING SEWD OVER SOUTHEASTERN 
ARIZONA WITH A TROUGH SW TO 25N118W AND TO 24N129W. BROAD SCALE 
ANTICYCLONIC FLOW IS PRESENT TO THE NW OF THE TROUGH...AND IS 
FUNNELING UPPER LEVEL FLOW NLY FLOW INTO THE BASE OF THE 
TROUGH. AN ACTIVE JET STREAM BRANCH STRETCHES FROM 23N130W EWD 
THROUGH THE BASE OF THE TROUGH. SATELLITE WATER VAPOR IMAGERY 
SHOWS OVERCAST TO BROKEN MID AND UPPER LEVEL CLOUDS STREAMING E 
AND NE WITHIN ABOUT 450 NM S OF THE JET STREAM BRANCH. WIDELY 
SCATTERED SHOWERS AND ISOLATED TSTMS ARE POSSIBLE UNDERNEATH 
THESE CLOUDS. THE WATER VAPOR IMAGERY ALSO DEPICTS MODERATE TO 
STRONG SUBSIDENCE INDUCING DRY AND STABLE ATMOSPHERIC 
CONDITIONS TO THE NW OF THE TROUGH WHERE BROKEN STRATOCUMLUS 
CLOUDS ARE SEEN SPREADING SW. SIMILAR DRY CONDITIONS ARE NOTED 
ACROSS THE ERN PORTION OF THE AREA SE OF THE JET STREAM RELATED 
CLOUDS.

THE SURFACE COLD FRONT ASSOCIATED WITH THE UPPER TROUGH IS 
ANALYZED FROM A 1005 MB LOW OVER S CENTRAL ARIZONA SSW ACROSS 
BAJA CALIFORNIA NEAR 27N112W AND TO 24N116.5W WHERE IT BECOMES A 
DISSIPATING COLD FRONT TO 24N129W. A VERY TIGHT PRES GRADIENT 
BEHIND IT INDUCED BY STRONG HIGH PRES OF 1036 MB WELL N OF THE 
AREA AT 38N141W WITH A RIDGE STRETCHING SEWD TO 32N136W TO NEAR 
22N130W IS BRINGING NW TO N 20-25 KT WINDS BEHIND THE 
FRONT...EXCEPT FOR N TO NE OF 20-25 KT BETWEEN 126W-129W. SEAS 
OF 10-16 FT IN LONG PERIOD NW SWELLS ARE BEHIND THE FRONT. THE 
UPPER TROUGH WILL QUICKLY SHIFT INLAND THE CENTRAL U.S. OVER THE 
NEXT 24-36 HRS PUSHING THE COLD FRONT TO ALONG A POSITION FROM 
28N108W TO 23N115W TO 20N125W...WITH N TO NE WINDS OF 20-25 KT N 
OF 28N BETWEEN 121W-127W. THE LARGE SEAS WILL SLOWLY SUBSIDE TO 
9-10 FT IN NW TO N SWELL. THE FRONT WILL THEN BEGIN TO RAPIDLY 
UNDERGO DISSIPATION THROUGH THE NEXT 48 HRS JUST SW OF W CENTRAL 
MEXICO WHILE TRANSITIONING TO A FRONTAL TROUGH. THE 1036 MB HIGH 
IS FORECAST TO REMAIN NEARLY STATIONARY OVER THE NEXT 24-36 
HRS...BUT BEGIN TO WEAKEN SLIGHTLY. THE PRES GRADIENT BETWEEN 
THE HIGH AND LOWER PRES ALONG THE ITCZ CONTINUES TO RESULT IN 
FRESH TO STRONG TRADE WINDS BETWEEN THE RIDGE AND ITCZ...FROM 
ROUGHLY N OF 10N W OF 129W AS HIGHLIGHTED BY THE 19 UTC ASCAT 
PASS. THE PRES GRADIENT WILL GRADUALLY RELAX THROUGH SAT NIGHT 
WITH THE SLIGHT WEAKENING OF THE PRESENT 1036 MB HIGH.

VERY LONG PERIOD NW SWELLS...WITH WAVE PERIODS BETWEEN 20-22 SEC 
MOVING ACROSS THE FAR NW PORTION WILL CONTINUE TO PROPAGATE 
THROUGH THESE WATERS THROUGH SAT...AND REACH THE REMAINDER OF 
THE WESTERN PART OF THE AREA BY LATE SAT. THESE SWELLS WILL 
GRADUALLY BUILD AS THEY PROPAGATE SEWD ACROSS THE AREA AND MIX 
WITH DECAYING NLY SWELLS BEHIND THE CURRENT COLD FRONT. 

GULF OF TEHUANTEPEC...THE NEXT GAP WIND EVENT IS FORECAST TO 
BEGIN LATE AROUND EARLY MON AFTERNOON WITH WINDS REACHING GALE 
FORCE AGAIN GOING IN MON EVENING. THIS NEXT EVENT WILL LIKELY BE 
ANOTHER STRONG ONE AS MARINE GUIDANCE INDICATES THAT IT WILL 
PERSIST THROUGH THE MIDDLE OF NEXT WEEK.

GULF OF CALIFORNIA...CURRENT W TO NW WINDS OF 20-25 KT OVER THE 
FAR NRN PORTION OF THE GULF NW OF THE FRONT DESCRIBED ABOVE ARE 
FORECAST TO DIMINISH TO 20 KT OR LESS EARLY TONIGHT AS THE PRES 
GRADIENT N OF THE FRONT BEGINS TO SLACKEN. HIGH PRES WILL BUILD 
BACK INTO THE REGION THIS WEEKEND FROM THE NW...AND INCREASE THE 
PRES GRADIENT TO SUPPORT NW WINDS OF 15-20 KT ACROSS THE ENTIRE 
GULF OF CALIFORNIA ON SUN EVENING. THESE WINDS WILL INCREASE 
FURTHER LATE SUN NIGHT INTO MON.
 
$$
AGUIRRE