000
AXPZ20 KNHC 201544
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON FEB 20 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1430 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

MONSOON TROUGH AXIS ANALYZED FROM 01N105W TO 01N111W TO 
DISSIPATING LOW PRES NEAR 05N117W 1010 MB TO 04N127W TO SECOND 
LOW PRES NEAR 0.5N131W 1010 MB...WHERE IT TRANSITIONS TO ITCZ 
AND CROSSES THE EQUATOR NEAR 132W. SCATTERED MODERATE CONVECTION 
NOTED WITHIN 150 NM EITHER SIDE OF TROUGH BETWEEN 105W AND 131W.

...DISCUSSION...

BROAD UPPER TROUGHING PREVAILS THIS MORNING ACROSS N PORTIONS OF 
THE AREA...ANCHORED ON A LONG WAVE TROUGH ACROSS THE NORTHERN 
PLAINS...WITH TWO EMBEDDED SHORTWAVE TROUGHS SWEEPING SE THROUGH 
THE BASE OF THE TROUGH AND ACROSS NE PORTIONS OF THE AREA. THESE 
TWO SHORTWAVES SUPPORT WEAK AND ILL DEFINED FRONTAL BOUNDARIES 
THAT CONTINUE TO REINFORCE FRESH NWLY FLOW FROM OFFSHORE OF 
CALIFORNIA EXTENDING S-SE TO THE OFFSHORE WATERS OF BAJA 
CALIFORNIA. AT THE SURFACE...AT 1034 MB HIGH WAS CENTERED NEAR 
34N144W WITH RIDGE EXTENDING SE TO NEAR 18N110W. THE PRESSURE 
GRADIENT BETWEEN THE HIGH AND LOWER PRESSURE ALONG THE SIERRA 
MADRES OF MEXICO IS PRODUCING AN AREA OF FRESH NWLY WINDS N OF 
26N E OF 120W...WHERE SEAS ARE RUNNING 10-13 FT IN NW SWELL. TO 
THE SOUTH OF THE HIGH...FRESH NELY TRADEWINDS COVER THE AREA 
FROM 06N TO 28N W OF 128W AND FROM 07N TO 14N BETWEEN 119W AND 
128W...WHERE SEAS ARE RUNNING 8 TO 13 FT IN MIXED NE AND NW 
SWELL. 

SE OF THESE FEATURES...A LARGE POOL OF ABUNDANT TROPICAL 
MOISTURE PERSISTS BETWEEN 105W AND 130W...ASSOCIATED WITH THE 
MONSOON TROUGH SEGMENT...AND TRAPPED BETWEEN THE PACIFIC HIGH 
PRES RIDGE...AND ELY TRADEWINDS SPILLING ACROSS CENTRAL AMERICA 
AND INTO THE FAR EPAC. SST'S IN THIS REGION REMAIN RELATIVELY 
WARM...YIELDING UNSTABLE LOWER ATMOSPHERIC CONDITIONS. THE FRESH 
NELY TRADES ALONG NW PORTIONS OF THE MOISTURE CONTINUE TO 
PRODUCE SCATTERED CONVECTION MENTIONED ABOVE...WHICH CONTINUES 
TO BE VENTILATED BY A PERSISTENT NEGATIVE TILT UPPER TROUGH FROM 
NEAR 12N124W TO 03N118W. A STRONG BLOCKING UPPER RIDGE ACROSS 
THE WRN CARIBBEAN AND MUCH OF THE GULF OF MEXICO IS HELPING TO 
MAINTAIN THE QUASISTATIONARY LOCATION OF THIS UPPER TROUGH. 
EXPECT THE SURFACE HIGH TO SHIFT NE OVER THE NEXT 48 HOURS AND 
REDUCE THE GRADIENT WINDS OFF BAJA CALIFORNIA...AND SHIFT THE 
AREA OF FRESH NE TRADES WWD OF 128W. 

MEANWHILE SUCCESSIVE PULSES OF NW SWELL WITH INITIAL PERIODS OF 
15-18 SECONDS WILL CONTINUE TO MIX WITH FRESH NE WIND SWELL OVER 
THE AREA W OF 110W.

...GAP WINDS...

GULF OF TEHUANTEPEC...WINDS AT SALINA CRUZ ON THE SOUTHERN COAST 
OF THE ISTHMUS WERE REPORTED TO BE 10 TO 12 KT WITH GUSTS AROUND 
20 KT OVER THE PAST FEW HOURS....WHILE WINDS AT COATZACOALCOS ON 
THE GULF OF MEXICO SIDE HAS SHIFTED SOUTHWEST. GALE FORCE WINDS 
THROUGH THE GULF OF TEHUANTEPEC ARE UNLIKELY...AND LATEST 
COMPUTER MODELS GUIDANCE ALSO SHOWS WINDS DROPPING BELOW 30 KT 
THERE THIS MORNING. THE GALE WARNING HAS THUS BEEN DISCONTINUED 
FOR TEHUANTEPEC...WITH WINDS EXPECTED TO FALL BELOW 20 KT BY 
EARLY AFTERNOON TODAY. 

GULF OF PAPAGAYO...NE TO E WINDS WILL CONTINUE TO PULSE TO 20 KT 
THROUGH THE GULF OF PAPAGAYO THROUGH MON MORNING...WITH THE 
STRONGEST WINDS OCCURRING IN THE EARLY MORNING WITH THE AID OF 
LOCAL DRAINAGE FLOW. THE TRADE WIND FLOW OVER THE SW CARIBBEAN 
WILL START TO INCREASE MON...ALLOWING FOR WINDS TO INCREASE TO 
20-25 KT ACROSS THE GULF OF PAPAGAYO BY EARLY TUE MORNING.

GULF OF PANAMA...A FEW SHIP OBSERVATIONS ON THE CARIBBEAN SIDE 
OF THE PANAMA CANAL WERE REPORTING N TO NE WINDS TO 20 KT. THE 
ENHANCED FLOW WILL PUSH ACROSS THE ISTHMUS OF PANAMA AND INTO 
THE GULF OF PANAMA TONIGHT INTO TUE AND PERSIST THROUGH WED. 

$$
STRIPLING