Eastern Pacific Tropical Weather Discussion

000
AXPZ20 KNHC 291005
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1005 UTC THU JAN 29 2015

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0945 UTC. 

...SPECIAL FEATURES...                                           
GULF OF TEHUANTEPEC GALE WARNING...A PERSISTENT TIGHT PRES 
GRADIENT ACROSS SOUTHEASTERN MEXICO JUST INLAND THE GULF 
CONTINUES TO SUPPORT A LONG DURATION EVENT OF N TO NE 30-40 KT 
WINDS THROUGH THE GULF OF TEHUANTEPEC. SHIP "ZCDI4" WAS AT 
POSITION 16N95W AT 00 UTC LAST NIGHT WHEN IT REPORTED NE WINDS 
OF 37 KT WITH COMBINED SEAS OF 19 FT. NE SWELLS THAT HAVE 
PROPAGATED DOWNSTREAM FROM THIS EVENT OVER THE PAST FEW DAYS ARE 
COMBINING WITH LONG PERIOD NW SWELLS. THE COMBINATION OF THESE 
SWELLS IS RESULTING IN A LARGE AREA OF SEAS 8-10 FT FROM 04N TO 
14N BETWEEN 92W AND 104W...AND ALSO FROM 06N TO 18N BETWEEN 113W 
AND 127W. FRESH TRADE WINDS OVER THE WESTERN PORTION OF THIS 
AREA ARE ALSO HELPING TO MAINTAIN THE SEAS HIGH THERE. MOST 
RECENT SEA SURFACE TEMPERATURE ANALYSIS REVEALS A POCKET OF COOL 
WATER OVER THE N CENTRAL PART OF THE GULF AS WELL AS DOWNSTREAM 
FROM THE GULF TO NEAR 12N BETWEEN 94W-97W DUE TO UPWELLING 
EFFECTS.

THE TIGHT PRES GRADIENT IS FORECAST TO GRADUALLY WEAKEN THROUGH 
SAT ALLOWING FOR THE GALE WINDS TO DECREASE TO MINIMAL THRESHOLD 
BY LATE FRI NIGHT...AND TO 20-25 KT BY SAT AFTERNOON WITH SEAS 
IN THE GULF SUBSIDING TO AROUND 14 FT FRI AND TO 9 OR 10 FT LATE 
SAT.

GULF OF PAPAGAYO GALE WARNING...A TIGHT PRES GRADIENT OVER THE 
FAR WESTERN CARIBBEAN SEA ALONG CENTRAL AMERICA IS HELPING TO 
SET OFF MINIMAL GALE FORCE FORCE THROUGH THE GULF. THESE WINDS 
WILL DIMINISH BELOW GALE FORCE BY EARLY THIS EVENING...AND   
PULSE TO 20-30 KT WITH THE ASSISTANCE OF DRAINAGE FLOW OFF THE 
MOUNTAINS IN THE LATE NIGHT AND EARLY MORNING HOURS THROUGH SAT. 
SEAS OF 9-11 FT WILL BUILD SLIGHTLY TO 12 FT BY THIS EVENING 
...AND SUBSIDE TO 9 FT LATE TONIGHT AND THROUGH LATE FRI NIGHT. 
NE SWELLS FROM PAPAGAYO WILL CONTINUE TO MERGE WITH THE SWELL 
FROM THE GULF OF TEHUANTEPEC THROUGH THE FORECAST PERIOD.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...           
THE ITCZ EXTENDS FROM 01N89W TO 05N90W TO 04N1110W TO 07N125W TO 
06N135W TO 07N140W. SCATTERED MODERATE CONVECTION IS WITHIN 120 
NM S OF THE ITCZ BETWEEN 117W-120W.

...DISCUSSION...                                                
A SLOW MOVING...NEGATIVELY TILTED UPPER LEVEL TROUGH IS THE MAIN 
FEATURE NOTED OVER THE AREA. IT STRETCHES FROM NEAR 32N124W SSE 
TO 20N122W TO 12N121W AND TO NEAR 04N112W. A SOUTHERLY JET 
STREAM BRANCH ON THE E SIDE OF THE TROUGH IS HELPING TO ADVECT 
ABUNDANT UPPER MOISTURE...MAINLY IN THE FORM OF BROKEN TO 
OVERCAST MID AND UPPER CLOUDS NNE ACROSS BAJA CALIFORNIA AND THE 
W CENTRAL AND NW PORTIONS OF MEXICO. UNDERNEATH THIS MOISTURE 
...SCATTERED SHOWERS AND ISOLATED TSTMS ARE POSSIBLE N OF 10N E 
OF THE TROUGH TO JUST INLAND MEXICO. A SURFACE REFLECTION OF 
THIS TROUGH IS ANALYZED ALONG 125W FROM 20N TO 28N. THE ASCAT 
PASS FROM 0514 UTC LAST NIGHT INDICATE A WEAK CYCLONIC SWIRL ON 
THE TROUGH NEAR 26N. LIGHTNING DENSITY DATA INDICATES MULTIPLE 
LIGHTNING STRIKES WITHIN THE AFOREMENTIONED ACTIVITY FROM 11N-
16N BETWEEN 119W-123W. THE DEEP LAYERED TROUGH WILL GRADUALLY 
SHIFT EASTWARD THROUGH THE NEXT 48 HRS WITH THE CLOUDINESS AND 
MOISTURE TO ITS E CONTINUING TO GRADUALLY SPREADING OVER MUCH OF 
BAJA CALIFORNIA AND THE WESTERN PORTION OF MEXICO N OF ABOUT 
18N. ELSEWHERE...NEARLY STATIONARY HIGH PRES OF 1026 MB IS 
CENTERED N OF THE AREA NEAR 36N130W. THE ASSOCIATED RIDGE 
EXTENDS FROM THE HIGH SWWD TO W OF 140W AT 29N...WHILE A WEAKER 
RIDGE EXTENDS SE FROM THE HIGH TO NEAR 21N116W. A WEAK TROUGH 
EXTENDS FROM 16N135W TO 15N138W. BROAD HIGH PRES AT THE 
MID/UPPER LEVELS COVERS THE EASTERN PART OF THE AREA TO THE 
ABOVE DESCRIBED UPPER TROUGH. A MEAN RIDGE AXIS STRETCHES FROM 
THE CENTRAL U.S. SSE ACROSS CENTRAL MEXICO TO 16N103W AND TO 
10N95W. THIS FEATURE IS MAINTAINING DRY AND STABLE ATMOSPHERIC 
CONDITIONS THROUGH ALL LEVELS OF THE ATMOSPHERE TO THE E OF A 
LINE FROM JUST S OF MANZANILLO TO THE BASE OF THE UPPER TROUGH. 

GAP WINDS...                                                     
SEE SPECIAL FEATURES ABOVE FOR GULFS OF TEHUANTEPEC AND 
PAPAGAYO GALE EVENTS.

GULF OF PANAMA...THE TIGHTENING PRES GRADIENT OVER THE WESTERN 
CARIBBEAN SEA IS RESULTING IN STRONG N WINDS TO FUNNEL SWD 
THROUGH THE GULF OF PANAMA AND TO NEAR 05N WITH SEAS TO 9 FT. 
THESE WINDS ARE FORECAST TO DIMINISH SLIGHTLY BY LATE 
TONIGHT...AND TO 20 KT OR LESS BY FRI AFTERNOON WITH SEAS 
SUBSIDING TO LESS THAN 8 FT.

GULF OF CALIFORNIA...NW WINDS OVER AND NEAR THE SOUTHERN PART OF 
THE GULF HAVE DIMINISHED SINCE YESTERDAY AS THE GRADIENT BETWEEN 
HIGH PRES RIDGING OVER THE EASTERN PACIFIC AND TROUGHING OVER 
THE WESTERN MEXICO SLACKENS. THE RESPITE WILL BE SHORT-LIVED AS 
THE PRES DIFFERENCE BETWEEN THE TROUGH OVER WESTERN MEXICO AND 
THE HIGH PRES RIDGING TIGHTENS SOME THIS AFTERNOON AND TONIGHT 
ALLOWING FOR A RETURN OF FRESH TO STRONG NW WINDS FROM ABOUT 23N 
TO 26N AND BETWEEN THE BAJA CALIFORNIA PENINSULA COAST AND 
MEXICO. HOWEVER...THESE WINDS DIMINISH AGAIN TO 20 KT OR LESS 
ON FRI AFTERNOON. 

$$ 
AGUIRRE