000
AXPZ20 KNHC 031507
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1605 UTC SAT JAN 03 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1300 UTC. 

...SPECIAL FEATURE...

GULF OF TEHUANTEPEC STORM WARNING...AN UPPER LOW MOVING ACROSS 
WESTERN TEXAS WILL PHASE WITH A NORTHERN STREAM TROUGH ON SUN 
AND SEND A STRONG COLD FRONT THROUGH CHIVELA PASS BY EVENING. 
THIS DENSE...COLD AIRMASS WILL MOVE OVER 26-28 CELSIUS WATERS IN 
THE GULF OF TEHUANTEPEC. THE LARGE TEMPERATURE DIFFERENCE 
BETWEEN THE AIR AND SEA WILL ALLOW FOR INCREASED VERTICAL 
MIXING. WINDS ARE EXPECTED TO RAPIDLY INCREASE TO GALE FORCE BY 
SUN NIGHT...REACHING STORM FORCE BY MON MORNING. WINDS OF GALE 
FORCE AND GREATER ARE EXPECTED TO PERSIST FOR SEVERAL DAYS.  

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
             
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 05N77W TO 03N87W. THE 
ITCZ AXIS WAS ANALYZED FROM 03N87W TO 07N101W TO 08N115W TO 
06N140W. SCATTERED MODERATE CONVECTION WAS WITHIN 180 NM N AND 
75 NM S OF THE AXIS BETWEEN 105W AND 116W. 

...DISCUSSION...                                                 

A 996 MB LOW PRES SYSTEM APPROXIMATELY 330 NM NE OF THE HAWAIIAN 
ISLANDS NEAR 26N155W EXTENDS A COLD FRONT SW TO THE N COAST OF 
THE BIG ISLAND OF HAWAII. GALE FORCE WINDS LIE AHEAD OF THIS LOW 
WELL W OF THE FORECAST AREA. THE LOW IS EXPECTED TO INTENSIFY AS 
IT MOVES N AND OCCLUDES OVER THE NEXT TWO DAYS. A STRONG MID-
LEVEL SHORTWAVE WILL MOVE INTO THE EASTERN PORTION OF THE DEEP 
LAYER TROUGH SUPPORTING THIS FRONT...TURNING THE TROUGH NEGATIVE 
TILT. WINDS ARE EXCEPTED TO INCREASE TO 30 KT IN NW WATERS ON 
SUN AND REMAIN JUST BELOW GALE FORCE AS THE FRONT APPROACHES NW 
WATERS MON. NW SWELL WILL OUTRUN THE FRONT...WITH SEAS 
INCREASING 16 FT BY MON MORNING. SHOWERS AHEAD OF THE FRONT ARE 
BEGINNING TO MOVE INTO NW WATERS TODAY...WITH THUNDERSTORMS 
EXPECTED OVER THE FORECAST AREA LATE SUN THROUGH MON. 

THE SUBTROPICAL HIGH HAS BEEN COMPRESSED EASTWARD BY THE 
TROUGHING IN THE CENTRAL PACIFIC. THE SUBTROPICAL RIDGE EXTENDS 
FROM 1026 MB HIGH PRES N OF THE AREA NEAR THROUGH 30N127W TO THE 
SOUTHERN TIP OF THE BAJA CALIFORNIA PENINSULA. THE PRES GRADIENT 
BETWEEN THE RIDGE AND THE ITCZ IS SUPPORTING A LARGE AREA OF 
MODERATE TO FRESH TRADE WINDS W OF 115W. THE SUBTROPICAL RIDGE 
SHOULD SHIFT SLIGHTLY E AS THE COLD FRONT IN THE CENTRAL PACIFIC 
MAKES ITS WAY EASTWARD. THIS WILL EXPAND THE AREA OF MODERATE TO 
FRESH TRADES EASTWARD AS WELL AS THE AREA OF 8-10 FT SEAS IN 
MIXED NW AND EASTERLY SWELL FOUND N OF THE ITCZ. 

A WEAK LOW-LEVEL TROUGH ANALYZED AT THE SURFACE FROM 14N112W TO 
05N115W IS FORECAST TO MOVE W AROUND 10 KT...WITH WINDS NEAR THE 
TROUGH EXPECTED TO INCREASE TO A FRESH TO STRONG BREEZE LATE SUN 
AND MON. THE CONVECTION DESCRIBED ALONG THE ITCZ IN THE SECTION 
ABOVE IS LOCATED IN THE VICINITY OF THIS TROUGH. SCATTERED 
MODERATE CONVECTION SHOULD CONTINUE NEAR THE TROUGH THROUGH MON. 

GAP WINDS...                                                   
GULF OF PAPAGAYO...HIGH PRES OVER THE CENTRAL ATLC EXTENDS A 
RIDGE SW THROUGH THE YUCATAN CHANNEL THEN S INTO THE GULF OF 
FONSECA. THE PRES GRADIENT BETWEEN THIS RIDGE AND THE MONSOON 
TROUGH/ITCZ...ALONG WITH LOCAL OVERNIGHT DRAINAGE 
EFFECTS...BROUGHT A STRONG NE BREEZE TO THE GULF OF PAPAGAYO 
THIS MORNING. WINDS MAY BRIEFLY DIP BELOW THE ADVISORY CRITERIA 
OF 20-25 KT THIS AFTERNOON...BUT ARE EXPECTED TO COME BACK IN 
EARNEST THEREAFTER AS THE ATLC RIDGE AXIS IS FORCED SOUTHWARD BY 
THE COLD FRONT ADVANCING THROUGH THE GULF OF MEXICO. WINDS ARE 
EXPECTED TO REACH NEAR GALE FORCE IN THE EARLY MORNING HOURS SUN 
AND MON...WITH SEAS REACHING AS HIGH AS 11 FT. WINDS AND SEAS 
ASSOCIATED WITH THE GAP WINDS IN PAPAGAYO WILL EXPAND W AND MEET 
UP WITH THOSE GENERATED FROM THE GULF OF TEHUANTEPEC BY THE END  
OF THE FORECAST PERIOD MON MORNING. 

GULF OF CALIFORNIA...HIGH PRES WILL BUILD IN THE GREAT BASIN N 
OF THE AREA SUN. THE GRADIENT BETWEEN THIS HIGH PRES AND LEE 
TROUGHING W OF THE SIERRA MADRE OCCIDENTAL WILL INDUCE 20-25 KT 
N-NW FLOW IN THE GULF OF CALIFORNIA N OF 25N BY SUN EVENING. 
LOOK FOR SEAS TO BUILD TO 8 FT BY MON MORNING AS THESE WINDS 
CONTINUE. 

$$
SCHAUER