000
AXPZ20 KNHC 211549
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN FEB 21 2010

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1545 UTC.

...ITCZ...

THE AXIS IS CENTERED ALONG 04N77W TO 06N100W TO 06N120W TO 
07N135W TO 06N140W. EXCEPT AS NOTED ABOVE...SCATTERED MODERATE 
TO STRONG WITHIN 120 NM OF THE AXIS BETWEEN 83W AND 93W. 
SCATTERED MODERATE WITHIN 60-90 NM N OF AXIS BETWEEN 112W AND 
127W. 

...DISCUSSION...

A SHEARED UPPER-LEVEL TROUGH IS OVER THE NW CORNER OF THE 
DISCUSSION AREA AND EXTENDS SW THROUGH 18N150W...SE OF THE 
HAWAIIAN ISLANDS. A SUBTROPICAL JET STREAM ROUNDS THE BASE OF 
THIS TROUGH AND CONTINUES EWD ALONG 25N TO THE COAST OF BAJA 
CALIFORNIA WITH CORE JET SPEEDS OF 125-150 KT. IN ADDITION TO 
MAINTAINING MAINLY A ZONAL FLOW PATTERN ACROSS MOST OF THE 
AREA...THIS JET ALSO CONTINUES TO ADVECT PLENTIFUL MID TO UPPER 
LEVEL MOISTURE FROM THE DEEP CENTRAL TROPICAL PACIFIC NE TO E 
ACROSS CENTRAL AND SOUTHERN MEXICO AND INTO THE BAY OF CAMPECHE 
AND NW CARIBBEAN SEA. THE UPPER TROUGH WILL CONTINUE TO SHEAR 
OUT AS IS MOVES EWD DURING THE NEXT 24 TO 48 HOURS. AN 
ASSOCIATED WEAKENING STATIONARY FRONT CLIPS THE FAR NW WATERS
ALONG 30N136W TO 28N140W. THIS FRONT WILL DISSIPATE LATER THIS 
AFTERNOON. OTHERWISE A 1024 MB SURFACE HIGH PRES CURRENTLY 
LOCATED NEAR 26N136W WILL REMAIN IN CONTROL OF THE WEATHER 
PATTERN ACROSS THE MAJORITY OF THE AREA DURING THE NEXT FEW 
DAYS. THE PRES DIFFERENCE BETWEEN THE HIGH AND LOWER PRES 
ASSOCIATED WITH THE ITCZ IS ALLOWING FOR AN AREA OF NE TO E 20 
TO 25 KT TRADE WINDS FROM 08N TO 18N W OF 120W. 0516 AND 0658 
UTC ASCAT PASSES VERIFIED THE EXISTENCE OF THESE WINDS. NUMERICAL
MODEL GUIDANCE AGREES THAT THE HIGH WILL SHIFT MAINLY E TO NEAR 
26N132W IN 24 HRS. AS A RESULT THE AREA OF TRADES IS EXPECTED TO 
EXPAND EASTWARD TO NEAR 110W IN 24 HOURS. AS THE HIGH MOVES 
EAST...WINDS ARE ALSO EXPECTED TO INCREASE NEAR THE BAJA 
CALIFORNIA PENINSULA IN ABOUT 24 HOURS AND ACROSS THE GULF OF 
CALIFORNIA IN APPROXIMATELY 36 HOURS AS PRES GRADIENT TIGHTENS 
BETWEEN THE HIGH AND LOWER PRES OVER NORTHERN MEXICO.

ELSEWHERE A NEARLY STATIONARY ELONGATED UPPER LEVEL ANTICYCLONE 
IS NOTED ALONG 08N BETWEEN 100W AND 115W. BROAD MID TO UPPER 
LEVEL ANTICYCLONIC FLOW COVERS THE AREA SOUTH OF THE ABOVE 
MENTIONED JET STREAM AND W OF 100W. A MID TO UPPER LEVEL TROUGH 
EXTENDS FROM NEAR THE GULF OF TEHUANTEPEC TO 06N96W. A DIFFLUENT 
PATTERN ALOFT BETWEEN THESE TWO UPPER LEVEL FEATURES IS HELPING 
TO INDUCE SCATTERED MODERATE TO STRONG CONVECTION EITHER SIDE OF 
A SURFACE TROUGH EMBEDDED IN THE ITCZ THAT EXTENDS FROM 09N103W 
TO 04N103W. 

A WEAK 1011 MB LOW IS ALSO EMBEDDED IN THE ITCZ NEAR 06N111W. A 
RECENT ASCAT PASS ONLY SHOWED WINDS OF 10 TO 15 KT AROUND THE 
LOW CENTER. THE MOST RECENT FORECAST GUIDANCE INDICATED WINDS 
AROUND THE LOW SHOULD REMAIN BELOW 20 KT THROUGH THE NEXT 48 
HOURS...WITH SOME DOUBT AS TO THE EXISTENCE OF THE LOW ITSELF 
BEYOND 36 HOURS. 

GAP WINDS...
THE EDGE OF AN 1136 UTC WINDSAT PASS CAPTURED AN AREA OF 20 TO 
25 KT WINDS IN THE GULF OF PAPAGAYO. THIS PASS WAS VERY NEAR THE 
TIME OF THE EXPECTED DIURNAL MAXIMUM IN THE SURFACE WINDS 
DUE TO DRAINAGE FLOW OFF THE CENTRAL AMERICAN LANDMASS. THESE 
WINDS ARE FORECAST TO QUICKLY DROP BELOW 20 KT LATER THIS 
AFTERNOON AND REMAIN SO OVER THE NEXT 48 HOURS.

LOOKING AHEAD...NWP MODELS ARE FORECASTING THE NEXT TEHUANTEPEC 
EVENT TO BEGIN BY LATE WED...WITH WINDS LIKELY REACHING GALE 
FORCE THU.

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

$$
COBB