000
AXPZ20 KNHC 052142
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU APR 05 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2115 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N77W 11N84W 6N95W 5N110W 4N140W. 
NUMEROUS MODERATE CONVECTION WITHIN 120 NM OF AXIS BETWEEN 
81W-94W. WIDELY SCATTERED SHOWERS/TSTMS WITHIN 75 NM OF AXIS 
BETWEEN 97W-110W AND BETWEEN 125W-130W.

...DISCUSSION...

SUBTROPICAL PACIFIC...
AN AMPLIFIED UPPER RIDGE AXIS LIES ALONG 110W RUNNING UP ALONG 
THE BAJA PENINSULA AND NW MEXICO...THEN NW ACROSS CALIFORNIA AND 
OREGON. A CUT-OFF MID/UPPER LOW IS EMBEDDED WITHIN THE RIDGE 
NEAR 32N123W BUT STILL HAS SIGNIFICANT EWD MOVEMENT DUE TO 
VIGOROUS WESTERLY FLOW N OF THE HAWAIIAN ISLANDS. A DANGLING 
UPPER TROUGH EXTENDS FROM 30N121W SW TO 20N137W AND IS 
SURROUNDED BY MODERATE/STRONG SUBSIDENCE. THE SUBTROPICAL JET 
RUNS ON THE S SIDE OF THE TROUGH FROM 17N140W TO 20N126W THEN TO 
30N117W WITH A TROPICAL MOISTURE FIELD STREAMING INTO NRN 
MEXICO. SURFACE HIGH PRES IS CENTERED NEAR 30N130W AND IS 
PRODUCING MOSTLY TRANQUIL WEATHER...ALTHOUGH WINDS AND SEAS ARE 
JUST BEGINNING TO INCREASE OVER THE FAR NW PORTION OF THE AREA 
IN ADVANCE OF A LARGE STORM SYSTEM. THE ASSOCIATED COLD FRONT IS 
EXPECTED TO MOVE INTO THE AREA FRI AFTERNOON ALTHOUGH IT WILL 
HAVE LOST MUCH OF ITS STEAM IN TERMS OF WIND. A FEW SHOWERS WILL 
BE POSSIBLE WITHIN THE FRONTAL BAND BEGINNING EARLY FRI THROUGH 
WHEN THE FRONT BECOMES STATIONARY LATE SAT.

TROPICAL PACIFIC...
THE SUBTROPICAL JET ENTERS THE AREA ALONG 14N WITH WESTERLY FLOW 
EXTENDING E TO 120W. THE FLOW BECOMES DIFFLUENT AT THAT 
POINT...WITH PART OF IT STREAMING NE INTO THE RIDGE OVER WRN 
MEXICO...AND THE OTHER PART STREAMING SE INTO AN UPPER TROUGH 
ALONG 15N101W EQ113W. MODERATE/STRONG SUBSIDENCE LIES BETWEEN 
100W-118W AT THE BASE OF THE RIDGE AND THE CONFLUENCE INTO THE 
TROUGH AND THIS IS HELPING TO PRODUCE BEAUTIFUL WEATHER ALONG 
THE MEXICAN AND CENTRAL AMERICAN COAST TO EL SALVADOR. TO THE 
E...THE UPPER SHEAR AXIS IS PRODUCING SOME UPPER DIFFLUENCE S OF 
CENTRAL AMERICA...AND THE ITCZ IS BEING PERTURBED NWD INTO COSTA 
RICA TO INITIATE NUMEROUS MODERATE CONVECTION BETWEEN 80W-94W. 
SOME OF THIS CONVECTION EXTENDS ACROSS SRN COSTA RICA AND MUCH 
OF PANAMA.

A GALE WARNING HAS BEEN ISSUED FOR THE GULF OF TEHUANTEPEC 
BEGINNING AT 0300 UTC THIS EVENING. A SURGE OF NORTHERLY WINDS 
IS NOTED OVER THE GULF OF MEXICO AT THIS TIME...AND ITS 
PROGRESSION APPEARS TO BE COINCIDENT WITH THE GFS SHOWING WINDS 
TO 35 KT OVER THE GULF OF TEHUANTEPEC TONIGHT. IN ADDITION...THE 
LAST GALE EVENT OVER TEHAUNTEPEC WAS MARCH 18 AND THE SEA 
SURFACE TEMPERATURES IN THE AREA HAVE SINCE REBOUNDED TO ABOUT 
29/30C WHICH SHOULD ALLOW FOR SUFFICIENT MIXING OF HIGHER WINDS 
FROM ABOVE. THE EVENT WILL BE SHORT-LIVED HOWEVER...WITH WINDS 
FALLING BELOW GALE FORCE BY 1800 UTC FRI.

$$
BERG