000
AXPZ20 KNHC 292217
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SUN JAN 29 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2115 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM LOW PRES NEAR 05N76W 1009 MB TO 
02N78W TO 05N86W TO 03N97W...WHERE IT TRANSITIONS TO ITCZ 
AXIS...CONTINUING ON TO 06N110W TO 04N120W TO 06N131W TO BEYOND 
05N140W. SCATTERED MODERATE CONVECTION NOTED WITHIN 180 NM S OF 
AXIS FROM 84W AND 93W. 

...DISCUSSION...
A SHARP MIDDLE TO UPPER LEVEL TROUGH HAS BECOME WELL ESTABLISHED 
ACROSS W PORTIONS OF THE AREA TODAY...EXTENDING FROM A 
PROGRESSIVE SHORTWAVE TROUGH MOVING ACROSS CALIFORNIA AND 
NEVADA...W-SW TO 33N135W TO A DEEP LAYERED CYCLONE CENTERED NEAR 
13N 149W...WITH BROAD TROUGH EXTENDING S ACROSS THE EQUATOR. THE 
DEEP LAYERED CYCLONE HAS BECOME CUT OFF FROM THE MEAN FLOW  WITH 
LOW AMPLITUDE DOWNSTREAM RIDGE S OF 20N CENTERED ALONG 130W. A 
DOWNSTREAM OF THIS FLAT RIDGE...A BROAD AND NEGATIVELY TILTED 
TROUGH EXTENDS FROM THE REMNANTS OF A SHEARED AND STRETCHED 
TROUGH NEAR 21N128W TO A BROAD BASE NEAR 06N106W. THIS TROUGH 
WILL CONTINUE TO DRIFT NE THROUGH MONDAY NIGHT AND ACT TO 
VENTILATE CONVECTION OCCURRING TO ITS E...AS THE COUPLED 
CONVECTION SHIFTS N AND NE WITH THE TROUGH. TO THE N OF THIS... 
A SHARP MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM A MIDDLE LEVEL 
CYCLONE NEAR 24N108W TO 19N120W...WITH A 60-70 KT JET SEGMENT TO 
THE S OF THE TROUGH HELPING TO MAINTAIN FAVORABLE ANTICYCLONIC 
SHEAR ACROSS THE AFOREMENTIONED CONVECTION. 

AT LOWER LEVELS...A LARGE POOL OF ABUNDANT TROPICAL MOISTURE 
CURRENTLY EXTENDS FROM THE ITCZ N TO 16N BETWEEN 104W AND 
116W...TRAPPED BETWEEN THE EPAC HIGH PRES RIDGE...AND GAP WIND 
FLOW SPILLING OUT OF THE GULF OF TEHUANTEPEC AND MERGING WITH 
THE WEAK NE TRADEWINDS. THE INCREASING LOW LEVEL FLOW UPSTREAM 
COMING FROM THE GULF OF TEHUANTEPEC HAS INCREASED THE LOW LEVEL 
FORCING ACROSS THIS UNSTABLE AREA THIS AFTERNOON...RESULTING IN 
A BURST OF DEEP CONVECTION FROM 11N TO 15N BETWEEN 102W AND 
108W...WITH FREQUENT LIGHTNING STRIKES INDICATED BY THE GLOBAL 
LIGHTNING NETWORK...AND CLOUD TOPS TO -67 C. AS MENTIONED 
ABOVE...THIS AREA OF ACTIVE CONVECTION IS EXPECTED TO SHIFT 
SLOWLY N AND NE DURING THE NEXT 36 HOURS.

THE EPAC SURFACE HIGH PRES RIDGE COVERS THE AREA N OF 16N W OF 
115W. NE TRADES AT 20 KT ARE OBSERVED ALONG THE SOUTHERN 
PERIPHERY OF THE THE RIDGE FROM 6N-16N W OF 132W...WITH SEAS TO 
8 FT.

STRONG HIGH PRES BUILDING OVER THE SOUTHERN U.S. HAS ONCE AGAIN 
TIGHTENED THE PRES GRADIENT ACROSS SOUTHERN MEXICO RESULTING IN 
GALE FORCE WINDS THROUGH THE GULF OF TEHUANTEPEC. THESE 
CONDITION ARE EXPECTED THROUGH EARLY MON AFTERNOON...THEN 
DECREASE TO BELOW GALE FORCE.

ELY WINDS OF 20 TO 25 KT CONTINUE TO BLOW THROUGH THE GULF OF 
PAPAGAYO AND EXTEND DOWNSTREAM TO 92W...AND ARE AIDING IN 
INITIATING SHOWERS AND TSTMS ALONG THE MONSOON THROUGH THERE. 
THIS STRONG GAP WIND FLOW IS EXPECTED TO PERSIST THROUGH TUE AND 
EXPAND DOWNSTREAM TO BEYOND 100W...WITH SEAS BUILDING TO 9 FT.

$$
STRIPLING