000
AXPZ20 KNHC 070920
TWDEP 

TROPICAL WEATHER DISCUSSION     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN JAN 7 2007

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 
0900 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 5N77W 4N85W 8N114W 4N133W 4N140W. 
ISOLATED MODERATE CONVECTION WITHIN 120 NM OF THE AXIS BETWEEN 
92W-110W. SCATTERED MODERATE FROM 6N-11N BETWEEN 112W-118W. 
SCATTERED MODERATE WITHIN 60 NM OF THE AXIS W OF 133W.

...DISCUSSION....

W OF 110W...
SYNOPTIC-SCALE PATTERN SHOWS A TEMPORARY SPLIT FLOW/BLOCKING 
HIGH REGIME W OF MEXICO AND THE UNITED STATES WITH THE POLAR JET 
CRASHING ONSHORE WELL N INTO BRITISH COLUMBIA...AND THE 
SUBTROPICAL JET EXTENDING FROM SE OF THE HAWAIIAN ISLANDS NE 
INTO NRN MEXICO. THIS HAS LEFT A "BAGGY" HEIGHT PATTERN OVER THE 
SUBTROPICAL WATERS WITH A VERY BROAD MID/UPPER TROUGH IN PLACE. 
WIDESPREAD UPPER MOISTURE IS STREAMING EWD ALONG AND S OF THE 
SUBTROPICAL JET...THEN TURNS NE INTO CENTRAL MEXICO. CONVECTION 
IS BEING ENHANCED ALONG THE ITCZ BETWEEN 110W-120W DUE TO UPPER 
DIFFLUENCE DOWNSTREAM OF A TROUGH EMBEDDED IN THE STREAM. 

A STRONG 1040 MB HIGH REMAINS IN CONTROL W OF CALIFORNIA NEAR 
36N134W ALTHOUGH GALE CONDITIONS WITHIN THE TRADES APPEAR TO 
HAVE SUBSIDED NOW. THE BLOCK IS EXPECTED TO RELINQUISH CONTROL 
BY 48-72 HRS AS A TROUGH DIGS ALONG THE U.S. WEST COAST AND THE 
RIDGE GETS PUSHED W. THIS WILL CAUSE THE SURFACE HIGH AND 
ASSOCIATED TRADES TO WEAKEN IN THE COMING DAYS. GALE CONDITIONS 
ARE LIKELY STILL OCCURRING OVER THE GULF OF CALIFORNIA DUE TO 
HIGH PRES OVER THE SW U.S. AND IS EXPECTED TO LAST FOR ANOTHER 
24 HRS OR SO.

E OF 110W AND GAP WINDS...
A MID/UPPER LEVEL HIGH AND RIDGE ARE ANCHORED ROUGHLY OVER NW 
CENTRAL AMERICA EXTENDING N INTO THE GULF OF MEXICO WITH 
CONTINUED DRY AND SUBSIDENCE E OF 100W AND N OF THE ITCZ. BASED 
ON LATEST MODEL GUIDANCE...A COLD FRONT OVER THE NW GULF OF 
MEXICO IS EXPECTED TO REACH SRN MEXICO LATER THIS EVENING WITH 
WINDS INCREASING TO 35 KT OVER THE GULF OF TEHUANTEPEC IN 24 
HRS. SSTS OVER THE GULF HAVE REBOUNDED TO 26-29C SINCE THE LAST 
EVENT AND THIS SHOULD PROVIDE ENOUGH INSTABILITY TO MIX DOWN 
ELEVATED WINDS A LITTLE BIT MORE THAN INDICATED BY THE 10-METER 
WIND FIELDS. ALSO IN LINE WITH THIS THINKING...CONDITIONS ARE 
EXPECTED TO REACH STORM FORCE (50 KT) IN A SMALL AREA BY MON 
EVENING. WINDS OVER THE GULF OF PAPAGAYO ARE CURRENTLY IN THE 
20-25 KT RANGE AND COULD INCREASE TO AS MUCH AS 30 KT BY MON 
NIGHT AS THE SYNOPTIC SCALE FAVORS A STRONGER PRES GRADIENT.

$$
BERG