000
AXPZ20 KNHC 170916
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU JAN 17 2008

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.
 
...ITCZ...

ITCZ AXIS IS CENTERED ALONG 3N77W 8N100W 9N115W 7N124W 8N140W. 
NO SIGNIFICANT CONVECTION.

...DISCUSSION...

NORTHWEST MEXICO...
AN EXCEPTIONAL LONGWAVE TROUGH CONTINUES TO CARVE ITS NICHE 
ACROSS THE UNITED STATES...EXTENDING FROM ABOUT THE MISSISSIPPI 
RIVER WESTWARD TO JUST OFF THE WEST COAST...AND SOUTHWARD ACROSS 
MUCH OF NORTHERN MEXICO AND THE WATERS W OF BAJA CALIFORNIA. A 
SHORTWAVE TROUGH CURRENTLY EXTENDS FROM THE FOUR CORNERS REGION 
SW TO 30N120W AND WILL PLUNGE SOUTHWARD ACROSS NW MEXICO DURING 
THE NEXT 24-48 HOURS. ALTHOUGH IT HAS BECOME SOMEWHAT DIFFUSE AS 
IT HAS CROSSED THE MOUNTAINS OF THE SW UNITED STATES...A SURFACE 
COLD FRONT HAS PUSHED S FROM THE RIO GRANDE VALLEY INTO THE 
SONORAN DESERT AND ACROSS NORTHERN BAJA. STRONG HIGH PRES HAS 
BUILT IN N OF THE FRONT...ANCHORED BY A 1037 MB HIGH OVER THE 
GREAT BASIN...AND THIS HAS TRIGGERED THE SANTA ANA WINDS ACROSS 
SOUTHERN CALIFORNIA AND NW MEXICO. IN FACT...A GALE WARNING HAS 
BEEN ISSUED FOR THE GULF OF CALIFORNIA N OF 28N WHERE WINDS ARE 
EXPECTED TO REACH UP TO 40 KT FROM NOW UNTIL THIS EVENING. IN 
ADDITION...THE STRONG WINDS ARE KICKING UP SAND AND DUST FROM 
THE MOJAVE DESERT WITH SAN FELIPE MEXICO REPORTING A SANDSTORM 
WITHIN THE PAST FEW HOURS.

ELSEWHERE N OF 20N...
AN UPPER RIDGE AXIS LIES ALONG 132W BUT HAS BECOME ALMOST 
PINCHED OFF FROM A CLOSED ANTICYCLONE LOCATED W OF NORTHERN 
CALIFORNIA. A DEEP-LAYERED CYCLONE REMAINS LOCATED W OF THE AREA 
BUT THE ASSOCIATED UPPER TROUGH HAS SHARPENED CONSIDERABLY AND 
BECOME NEGATIVELY TILTED WITH THE BASE JUST GRAZING THE NW PART 
OF THE AREA. WIDESPREAD CIRRUS LIES E OF THE TROUGH AXIS BETWEEN 
124W AND 139W EMBEDDED WITHIN THE RIDGE.

S OF 20N...
THE UPPER FLOW OVER THE TROPICS HAS FLATTENED OUT SINCE THIS 
TIME YESTERDAY. WESTERLY WINDS WITH JET CORE SPEEDS OF 100 KT 
CROSSES 140W THEN GRADUALLY TURNS INTO THE BASE OF A TROUGH NOW 
LOCATED ALONG 114W. THE AMPLITUDE OF THE TROUGH HAS DECREASED 
AND THUS SO HAS THE ASSOCIATED DIFFLUENCE...KEEPING CONVECTIVE 
ACTIVITY AT A MINIMUM. SOUTHWESTERLY FLOW DOMINATES E OF 110W 
WITH SOME UPPER LEVEL MOISTURE BEING ADVECTED ACROSS CENTRAL 
MEXICO...AND DRY AIR SPREADING ACROSS ALL OF CENTRAL AMERICA. 
THE GAP FLOWS ARE QUIET AT THE MOMENT BUT WINDS MAY INCREASE 
BACK TO 20 KT OVER THE GULF OF PAPAGAYO IN 24 HOURS. GALES ARE 
EXPECTED OVER THE GULF OF TEHUANTEPEC BY SAT EVENING AS HIGH 
PRES BUILDS ACROSS THE GULF OF MEXICO.

$$
BERG