000
AXPZ20 KNHC 312213
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SUN JAN 31 2010

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2115 UTC.

...ITCZ...

THE ITCZ AXIS IS ANALYZED ALONG 06N77W TO 03N88W TO 05N107W TO 
05N125W TO 03N140W. NO SIGNIFICANT CONVECTION.  

...DISCUSSION...

AT THE UPPER LEVELS...A BROAD FLAT MIDDLE/UPPER LEVEL RIDGE 
DOMINATES THE MAJORITY OF THE FORECAST AREA WITH STRONG UPPER 
LEVEL W TO W-NW FLOW NOTED N OF 10-15N. FEW UPPER LEVER 
IMPULSES/PERTURBATIONS ARE EMBEDDED WITHIN THIS FLOW...BUT ARE 
GENERALLY ENCOUNTERING A STABLE MIDDLE TROPOSPHERE...YIELDING 
FAIR STABLE WEATHER ACROSS THIS AREA. THIS STRONG MID LATITUDE 
FLOW SPLITS NEAR 110W FROM 10-18N...AS IT APPROACHES 
MIDDLE/UPPER LEVEL TROUGHING ACROSS THE WRN U.S. INTO MEXICO AND 
CENTRAL AMERICA. NEAR 110W...ONE BRANCH OF THE JET TURNS NE AND 
JOINS A VERY BROAD REGION OF ANTICYCLONIC FLOW ACROSS MEXICO AND 
CENTRAL AMERICA AND OVER THE CARIBBEAN/E GLFMEX UPPER RIDGE... 
WHILE THE SRN BRANCH CONTINUES DIVING SE AND THROUGH THE BASE OF 
THE LONGWAVE UPPER TROUGH NEAR 06N82W. AN UPPER CYCLONE MOVING 
INTO THE GREAT PLAINS EXTENDS S TO NEAR 27N114W...WITH THIS SRN 
PORTION OF THE TROUGH LAGGING ABOUT 304 DEGREES BEHIND A SRN 
STREAM L/W TROUGH FROM NEAR 30N109W SE TO NEAR 06N82W. THESE TWO 
FEATURES WILL BECOME MORE IN PHASE ACROSS THE N CENTRAL GULF OF 
MEXICO ON TUE AS THEN LIFT NE TO E-NE ACROSS THE WEAKENING 
DOWNSTREAM RIDGE. 

AT THE SURFACE...A WEAK 1018 MB HIGH IS LOCATED NEAR 32N125W AND 
IS FORECAST TO SLIDE SE TO NEAR 28N122W IN 24 HOURS. THE 
PRESSURE GRADIENT TO THE S OF THIS WEAK RIDGE IS PRODUCING A 
MODEST AREA OF NORTHEAST TRADE WINDS IN THE 20-25 KT RANGE FROM 
04N TO 10N W OF 130W AS INDICATED BY RECENT SCATTEROMETER 
PASSES. EXPECT THE GRADIENT TO SLIGHTLY RELAX IN 24 HOURS BUT 
WILL INCREASE AGAIN BY 48 HOURS. WEAK SURFACE TROUGHS EMBEDDED 
WITHIN THE ITCZ ARE LOCATED ALONG 107W/108W AND ALONG 
131W/132W...BOTH S OF 8N. SHALLOW CONVECTION IS NOTED NEAR THESE 
TROUGHS. A COLD FRONT WAS ENTERING THE FAR NW PORTION OF THE 
AREA FROM 30N135W TO 24N140W. S TO SW WINDS OF 20 KT WERE 
NOTED N OF 29N E OF THE FRONT. THIS FRONT IS FORECAST TO MOVE TO 
A POSITION FROM 30N131W TO 24N140W IN 24 HOURS...THEN  THE FRONT 
DISSIPATE IN ABOUT 48 HOURS.

REGIONAL SEAS CONTINUE TO BE DOMINATED BY NWLY SWELL...AND ARE 
RUNNING IN THE 8 TO 12 FOOT RANGE N OF 20N W OF 125W. A NEW 
PULSE OF NW SWELL WILL PROPAGATE THROUGH THE AREA IN THE WAKE OF 
THE AFOREMENTIONED COLD FRONT.

GAP WINDS...
A HIGH RESOLUTION 1245 UTC ASCAT PASS SHOWED GALE FORCE WINDS OF 
35-40 KT THROUGH THE GULF OF TEHUANTEPEC WHERE A GALE WARNING 
REMAINS IN EFFECT. WINDS ARE EXPECTED TO DIMINISH BELOW GALE 
FORCE IN ABOUT 18-24 HOURS. GAP WINDS IN THE GULF OF PAPAGAYO 
ARE 20 TO 25 KNOTS AND WILL PULSE UP AND DOWN OVER THE NEXT 48 
HOURS...WHILE NLY FLOW THROUGH THE GULF OF PANAMA WILL PULSE UP 
AND DOWN AT OR BELOW 20 KT THROUGHOUT THE NEXT FEW DAYS. 

FOR ADDITIONAL INFORMATION PLEASE VISIT 
HTTP://WWW.HURRICANES.GOV/MARINE

$$
STRIPLING