000
AXPZ20 KNHC 220258
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU APR 22 2010

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0245 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED FROM 08N83W TO 
07N100W TO 05N115W TO 05N120W TO 03N140W. SCATTERED MODERATE 
WITH ISOLATED STRONG CONVECTION WAS S OF THE ITCZ TO EQUATOR 
BETWEEN 119W AND 123W WHILE SCATTERED MODERATE CONVECTION WAS 
ELSEWHERE WITHIN 180 NM S AND 120 NM N OF THE ITCZ AXIS W OF 
108W. SCATTERED MODERATE CONVECTION LIED FROM 75 NM TO 210 NM S 
OF AXIS BETWEEN 93W AND 96W. 


...DISCUSSION...

AN AMPLIFIED MID TO UPPER LEVEL TROUGH OVER THE AREA N OF 20N E 
OF 130W AND EXTENDING N INTO CALIFORNIA HAS CUT OFF FROM THE 
NORTHERN STREAM AND WILL DRIFT E THROUGH THE DESERT SW AND FOUR 
CORNERS REGION OVER THE NEXT TWO DAYS. THE 1720 UTC ASCAT PASS 
SHOWED 20 TO 25 KT NW TO N WINDS OVER NE WATERS ASSOCIATED WITH 
THE STRONG PRES GRADIENT BETWEEN THIS TROUGH AND 1034 MB HIGH 
PRES NW OF THE AREA NEAR 36N147W. SIMILARLY...THE PRES GRADIENT 
S OF THE HIGH BETWEEN IT AND THE ITCZ HAS BROUGHT STRONG 
EASTERLY TRADE WINDS TO W WATERS ACCORDING TO THE 1902 UTC ASCAT 
PASS. THE HIGH PRES SYSTEM IS FORECAST TO WEAKEN AS IT IS NUDGED 
EASTWARD OVER THE NEXT TWO DAYS BY A COLD FRONT PASSING OVER ITS 
NW EDGE. AS THE TROUGH OVER THE SW U.S. MOVES EAST THU...LOOK 
FOR THE STRONGEST PRES GRADIENT TO MOVE E AS WELL...SEPARATING 
THE STRONGEST WINDS FROM THE EASTERLY TRADES AND POSSIBLY 
BRINGING W WINDS TO 20 KT WITHIN THE RELATIVELY SMALL AREAS 
DOWNWIND OF MOUNTAIN PASSES IN THE NORTHERN GULF OF CALIFORNIA. 
WINDS ARE EXPECTED TO DROP BELOW 20 KT OFF THE BAJA AND IN THE 
GULF OF CALIFORNIA FRI AS THE PRES GRADIENT SLACKENS THERE AND 
TIGHTENS TO THE SOUTH ALONG THE MEXICAN COAST NEAR MANZANILLO 
WITH NW WINDS EXPECTED TO REACH 20 KT BY LATE AFTERNOON. TRADE 
WINDS WILL REMAIN STRONG OVER W WATERS THROUGH THE FORECAST 
PERIOD.

STRONG MOISTURE CONVERGENCE ALONG THE ITCZ BETWEEN THE NE TRADES 
AND STRONG SE TRADES S OF THE EQUATOR HAS PROVIDED FUEL FOR 
CONVECTION W OF 115W. A 1008 MB SURFACE LOW EMBEDDED IN THE ITCZ 
AT 0000 UTC NEAR 05N127W AND A TROUGH TO ITS W FROM 09N132W TO 
02N132W HAVE FURTHER HELPED POOL LOW LEVEL MOISTURE. THESE 
FEATURES LIE UNDER AN AREA OF BROAD ANTICYCLONIC TURNING...THE 
CENTER OF WHICH IS FORECAST TO GRADUALLY SHIFT E OVER THE NEXT 
FEW DAYS BUT REMAIN W OF 115W. THIS WESTERN PORTION OF THE ITCZ 
IS EXPECTED TO REMAIN CONVECTIVELY ACTIVE AS A RESULT. A BROAD 
60-80 KT WEST-SOUTHWESTERLY UPPER JET THAT EXTENDS FROM THIS 
CONVECTIVE REGION OF THE ITCZ INTO CENTRAL MEXICO IS 
TRANSPORTING THE MID TO UPPER LEVEL MOSITURE NORTHEASTWARD. 
FARTHER E...THE CONVECTION FOUND NEAR THE ITCZ W OF COSTA RICA 
EARLIER THIS EVENING HAS NEARLY DISSIPATED. THE RIDGE AXIS THAT 
WAS OVER THIS AREA IS CONTRACTING E AND WILL BE REPLACED BY 20 
TO 30 KT SOUTHERLY FLOW ALOFT OVERNIGHT ON THE EASTERN SIDE OF 
AN UPPER TROUGH BUILDING BETWEEN 90W-100W. THE UPPER TROUGH WILL 
CUT OFF A LOW S OF THE GALAPAGOS ON FRI AND ALLOW AN ANTICYCLONE 
TO BUILD OVER THE ITCZ BETWEEN 95W AND 105W...INCREASING THE 
CHANCE OF CONVECTION.

$$
SCHAUER