000
AXPZ20 KNHC 150923
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI FEB 15 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 
0700 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 07N92W TO 1009 MB LOW 
PRES 08N97W TO 04N101W. ITCZ AXIS WAS ANALYZED FROM 04N101W TO 
08N112W TO 04N140W. ISOLATED MODERATE CONVECTION WAS WITHIN 630 
NM N OF THE AXIS BETWEEN 128W AND 132W. 

...DISCUSSION...
THE 1035 MB SUBTROPICAL HIGH NEAR 39N135W EXTENDS A RIDGE AXIS 
SOUTHWARD THROUGH 32N135W TO 19N110W. THE PRESSURE GRADIENT 
BETWEEN THIS RIDGE AND THE ITCZ IS STILL STRONG ENOUGH TO 
SUPPORT 25-30 KT WINDS N OF THE ITCZ MAINLY BETWEEN 130W-135W 
ACCORDING TO THE 0600 UTC ASCAT PASS. THE SUBTROPICAL HIGH WILL 
BE IMPEDED ON BY A COLD FRONT TODAY AND WILL WEAKEN AS IT SHIFTS 
SOUTHWESTWARD...EVENTUALLY MERGING WITH HIGH PRESSURE BEHIND THE 
COLD FRONT OVERNIGHT TONIGHT. THIS WILL WEAKEN THE RIDGING OVER 
THE AREA AND CAUSE TRADES TO GRADUALLY SHIFT WESTWARD AND 
DIMINISH TO A STRONG NE BREEZE THROUGH EARLY SUN. 

AN UPPER TROUGH EXTENDS THROUGH THE FORECAST AREA FROM 32N134W 
TO 12N134W TO 00N116W. A 100-120 KT UPPER JET IS ON THE E SIDE 
OF THE TROUGH FROM 15N130W THROUGH 30N120W THEN EAST- 
SOUTHEASTWARD INTO NW MEXICO. STRONG UPPER LEVEL DIFFLUENCE 
BETWEEN THE REAR RIGHT QUADRANT OF THIS JET AND THE FRONT LEFT 
QUADRANT OF A WESTERLY UPPER JET ALONG 02N W OF THE TROUGH AXIS 
IS LIFTING MOISTURE POOLED ALONG THE ITCZ NEAR 130W. A SWATH OF 
HIGH CLOUDS TRACKS NORTHEASTWARD FROM THIS AREA ALONG THE UPPER 
JET TO THE BAJA CALIFORNIA PENINSULA...WITH ISOLATED SHOWERS 
MOST LIKELY FOUND IN THE REGION OF HIGHEST LOW LEVEL MOISTURE 
BETWEEN THE ITCZ AND 16N. 

GAP WINDS...
GULF OF CALIFORNIA...THE SOUTHWESTERN EDGE OF THE MEAN UPPER 
TROUGH OVER THE CENTRAL U.S. EXTENDS ALONG THE RIO GRANDE VALLEY 
THIS MORNING. THIS PORTION OF THE MEAN TROUGH WILL BE RELOADED 
WITH BOTH NORTHERN STREAM ENERGY MOVING THROUGH THE INTERIOR 
WESTERN U.S. AND ENERGY EJECTED FROM THE AFOREMENTIONED UPPER 
TROUGH PRIMARILY ALONG 134W. AT THE SURFACE...THE STRONG 
PRESSURE GRADIENT BETWEEN THE SUBTROPICAL RIDGE AND TROUGHING 
OVER NORTHERN MAINLAND MEXICO ASSOCIATED WITH THE MEAN TROUGH 
ALOFT IS FORCING FRESH TO STRONG N-NW WINDS IN THE CENTRAL THE 
GULF OF CALIFORNIA. THE RELOADING OF THE UPPER TROUGH WILL 
STRENGTHEN THE SURFACE TROUGHING OVER MAINLAND MEXICO...ALLOWING 
THE PRES GRADIENT TO REMAIN STRONG EVEN AS THE SUBTROPICAL RIDGE 
WEAKENS. A FRESH TO STRONG BREEZE IS FORECAST TO CONTINUE UNTIL 
SAT EVENING. 

GULF OF TEHUANTEPEC...A WEAK COLD FRONT HAS MOVED INTO THE 
ISTHMUS OF TEHUANTEPEC WITH LITTLE FANFARE IN THE PACIFIC. 
HOWEVER...A SECONDARY SURGE OF COLD AIR WILL REINFORCE THE COLD 
FRONT OVERNIGHT...WITH NORTHERLY GALES EXPECTED IN THE GULF OF 
TEHUANTEPEC BY SUNRISE SAT STRENGTHENING TO STORM FORCE BY SAT 
EVENING AND PERSISTING THROUGH THE END OF THE FORECAST PERIOD 
EARLY SUN MORNING. 

GULF OF PAPAGAYO...STRENGTHENING HIGH PRESSURE OVER THE GULF OF 
MEXICO AND NW CARIBBEAN WILL INCREASE THE PRESSURE GRADIENT 
BETWEEN THIS RIDGING AND LOWER PRESSURE TO THE SW ALONG THE ITCZ 
TO YIELD FRESH TO STRONG NE WINDS IN THE GULF OF PAPAGAYO BY 
EARLY SUN MORNING.  

$$
SCHAUER