000
AXPZ20 KNHC 260328
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU JAN 26 2012

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0230 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM 05N74W TO 02N81W TO 04N95W WHERE IT 
TRANSITIONS TO ITCZ AXIS...CONTINUING ON TO 06N107W TO 06N124W 
TO 04N134W TO 04.5N140W. SCATTERED MODERATE TO STRONG CONVECTION 
NOTED WITHIN 150 NM OF AXIS BETWEEN 101W AND 107W. SCATTERED TO 
LOCALLY NUMEROUS MODERATE TO STRONG CONVECTION NOTED WITHIN 150 
NM N AND 60 NM S OF AXIS FROM 125W TO 133W.

...DISCUSSION...
A LARGE UPPER LEVEL ANTICYCLONIC CIRCULATION OVER THE NORTHERN 
PORTION OF THE DISCUSSION AREA IS CENTERED NEAR 30N126W... 
SPANNING E TO W BETWEEN 115W AND 135W...AND GENERALLY N OF 
23N...AND IS PART OF A NEARLY STATIONARY BLOCKING RIDGE ACROSS 
THE EPAC. TO ITS E...A MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM 
A VIGOROUS DEEP LAYERED CYCLONE OVER W CENTRAL TEXAS...SW ACROSS 
N MEXICO TO NEAR 22N120W...THEN MEANDERS IN A TUTT LIKE FASHION 
S OF THE UPPER RIDGE TO A WEAK MIDDLE LEVEL CYCLONE NEAR 
24N138W. DEEP LAYERED NLY FLOW BETWEEN THE CYCLONE OVER TEXAS 
AND THE UPPER ANTICYCLONE CONTINUES TO MAINTAIN COLD AIR 
ADVECTION ACROSS NE PORTIONS OF THE AREA E OF 125W...INCLUDING 
BAJA CALIFORNIA AND NW MEXICO. THE UPPER CYCLONE WILL CONTINUE 
TO SHIFT E ALONG THE N GULF OF MEXICO COAST THROUGH THU NIGHT 
WHILE THE UPPER RIDGE SHIFTS SLOWLY NW...AND TERMINATES THE 
INFLUX OF COLDER AIR INTO BAJA CALIFORNIA AND NW MEXICO. 

AN UPPER RIDGE EXTENDS FROM COLOMBIA ACROSS CENTRAL AMERICA INTO 
THE NW CARIBBEAN THEN N ACROSS THE FAR ERN GULF OF MEXICO. 
EXCEPT FOR ISOLATED MODEST CONVECTION NEAR THE ITCZ AND MONSOON 
TROUGH...SUBSIDENCE GENERALLY COVERS THE AREA E OF 100W. S OF 
THE BLOCKING RIDGE AND W OF 100W...UPPER LEVEL WESTERLIES 
GENERALLY PREVAIL...WITH A 60-70 KT TROPICAL JET SEGMENT ALONG 
THE EQUATOR BETWEEN 125W AND 140W. THE UPPER FLOW IN THIS REGION 
BETWEEN 120W AND 140W IS MILDLY DIFFLUENT. HOWEVER...STRONG LOW 
LEVEL FORCING FROM THE TRADEWIND FLOW JUST N OF THE ITCZ IS 
PRODUCING A CLUSTER OF DEEP CONVECTION DESCRIBED ABOVE...AND 
ACTING TO INDUCE FURTHER DIVERGENCE ALOFT BETWEEN 135W AND 140W.

AT THE SURFACE...A 1029 MB HIGH IS JUST N OF THE DISCUSSION AREA 
CENTERED NEAR 34N131W...AND NEARLY STATIONARY. THE ASSOCIATED 
HIGH PRES RIDGE COVERS THE AREA N OF 13N W OF 105W...WITH NE 
TRADES AT 20-25 KT OCCURRING ACROSS THE SOUTHERN PERIPHERY OF 
THE RIDGE FROM 06N TO 28N W OF 127W...AND FROM 10N TO 27N 
BETWEEN 122W AND 127W. COMBINED SEAS ACROSS THIS AREA ARE 
RUNNING 8 TO 12 FT. THE PRES GRADIENT BETWEEN THE HIGH AND LOWER 
PRES ALONG THE SIERRA MADRE OCCIDENTALES CONTINUES TO YIELD 
FRESH N-NW FLOW THROUGH THE LENGTH OF THE GULF OF CALIFORNIA... 
WITH A 1656 UTC ASCAT PASS REVEALING WINDS TO 25 KT. 
OTHERWISE...MODERATE TO LARGE NW SWELLS DOMINATE THE WATERS 
ACROSS MUCH OF THE AREA W OF 115W... MAINTAINING SEAS OF 8 FT 
AND HIGHER.

A STRONG COLD FRONT IS ENTERING THE NW GULF OF MEXICO THIS 
EVENING AND WILL SHIFT SE TO THE YUCATAN PENINSULA BY THURSDAY 
EVENING. STRONG HIGH PRES WILL BUILD BEHIND THE FRONT WHICH WILL 
TIGHTEN THE PRES GRADIENT OVER SOUTHERN MEXICO THU AFTERNOON 
THROUGH FRI. THIS WILL RESULT IN GALE FORCE WINDS THROUGH THE 
GULF OF TEHUANTEPEC BY SUNRISE FRI MORNING...WHICH ARE EXPECTED 
TO DIMINISH BELOW GALE FORCE BY FRI EVENING.

$$
STRIPLING