000
AXPZ20 KNHC 040242
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SUN JUL 04 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 
0230 UTC.

...ITCZ...
AXIS ALONG 08N82W TO 09N94W TO 10N115W TO 07N130W TO 08N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS WITHIN 120 NM 
N OF AXIS BETWEEN 99W AND 110W. SCATTERED MODERATE WITHIN 120 NM 
EITHER SIDE OF THE AXIS W OF 128W.  

...TROPICAL WAVE...
A TROPICAL WAVE ALONG 80W N OF 05N IS ESTIMATED TO BE MOVING W 
AT 12 KT OVER THE PAST 24 HOURS. THE WAVE WAS EMBEDDED IN AN 
AREA CHARACTERIZED BY MODERATE TO STRONG EASTERLY FLOW ALOFT 
WHICH WAS LIMITING CONVECTION ASSOCIATED WITH THE WAVE. THE 
NORTHERN PORTION OF THE WAVE OVER THE CARIBBEAN APPEARED TO BE 
THE MOST ACTIVE.

...DISCUSSION...
COMPLEX BLOCKING UPPER PATTERN EXISTS TO THE NW OF THE 
DISCUSSION AREA WITH A QUASI STATIONARY UPPER LEVEL ANTICYCLONE 
NEAR 24N126W AND AN ASSOCIATED RIDGE EXTENDING ENE ACROSS SRN 
BAJA CALIFORNIA TO ANOTHER ANTICYCLONE OVER NRN MEXICO NEAR 
28N104W. RIDGE ALSO EXTENDS SW TO A COL NEAR 19N145W. MID TO 
UPPER LEVEL CONVERGENCE BETWEEN THE RIDGE AND A DEEP LAYERED 
TROUGH ALONG THE INTERMOUNTAIN WEST CONUS YIELDED A VAST AREA OF 
DEEP LAYERED SUBSIDENCE OVER MOST OF THE AREA N OF 20N W OF 110W 
WITH THE STRONGEST SUBSIDENCE NOTED TO THE N OF THE RIDGE AXIS.

THE ANTICYCLONE OVER NRN MEXICO IS MAINTAINING AN AREA OF 
UPPER LEVEL DIVERGENT FLOW THAT IS HELPING TO SUSTAIN DEEP 
CONVECTION ACROSS THE NRN STATES OF MEXICO...ASSOCIATED WITH THE 
REMNANTS OF FORMER TROPICAL CYCLONE ALEX. A NARROW MID TO UPPER 
LEVEL SHEAR AXIS EXTENDS FROM A SMALL CIRCULATION OVER THE N 
CENTRAL GULF OF MEXICO NEAR 27N85W SSW ACROSS THE BAY OF CAMPECHE
TO THE E PACIFIC NEAR 10N99W...JUST N OF THE ITCZ. NE TO E FLOW 
OCCURRING BETWEEN THIS SHEAR AXIS AND THE UPPER RIDGE NOTED 
ABOVE IS CREATING A BROAD ZONE OF UPPER DIFFLUENCE N OF THE ITCZ 
W OF 100W WITH UPPER LEVEL EASTERLY WINDS OF 55 TO 75 KT PER 
SATELLITE DERIVED WINDS. THIS BROAD EASTERLY JET WAS ADVECTING 
MID TO UPPER LEVEL MOISTURE WWD ACROSS THE PACIFIC S OF 20N AND
E OF 120W. 

AT THE SURFACE...BROAD 1036 MB HIGH PRES WELL N OF THE 
DISCUSSION AREA NEAR 41N142W EXTENDS A RIDGE AXIS SE THROUGH 
30N133W TO 19N120W. A TIGHT PRESSURE GRADIENT BETWEEN THE BROAD 
SURFACE RIDGE AND CLIMATOLOGICAL TROUGHING ALONG THE SIERRA 
MADRES IS PRODUCING GALE FORCE WINDS ALONG THE NORTHERN 
CALIFORNIA COAST AND NW TO N WINDS OF 20-25 KT JUST N OF THE 
DISCUSSION AREA. THE LOWER PRESSURES OVER THE SW CONUS HAS 
RESULTED IN A FETCH OF FUNNELED SE TO S WINDS OF 20 TO 25 KT 
WITHIN THE GULF OF CALIFORNIA N OF 25N. FORECAST WINDS ARE 
EXPECTED TO DIMINISH ON BOTH SIDES OF BAJA CALIFORNIA WITHIN 24 
HOURS. ELSEWHERE AT THE SURFACE...A WEAK LOW LEVEL CYCLONIC 
CIRCULATION WAS NOTED ALONG THE ITCZ ALONG 94W.

VERY LONG PERIOD...20-21 SECOND...S-SW SWELL TRAIN ORIGINATING 
IN THE SRN HEMISPHERE IS MOVING NWD OVER THE ENTIRE DISCUSSION 
AREA AND IS IMPACTING BAJA CALIFORNIA AND NW MEXICO. THIS SWELL 
IS IN THE PROCESS OF MERGING WITH ESTABLISHED NLY SWELLS N OF 
23N AND IS EXPECTED TO PRODUCE HIGH AND CONFUSED SEAS. THIS 
SWELL WILL CONTINUE OVER THE NEXT 12-24 HOURS AND MAY RESULT IN 
LARGE BREAKING WAVES AND DANGEROUS SURF CONDITIONS ALONG EXPOSED 
SHOALS...REEFS AND BEACHES. 

$$
COBB