| HOME | ARCHIVES | FORECASTS | IMAGERY | ABOUT NHC | RECONNAISSANCE |

---

Eastern Pacific Tropical Weather Discussion (Text)

000
AXPZ20 KNHC 281006
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1005 UTC WED JAN 28 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 PRESSURE 
GRADIENT ACROSS SOUTHEASTERN MEXICO IS PRODUCING A LONG DURATION 
EVENT OF N TO NE 30-45 KT WINDS THROUGH THE GULF OF TEHUANTEPEC. 
SHIP "C6FR3" NEAR 15N94W REPORTED NE WINDS AT 43 KT AT 04 AND 06 
UTC. THE GALE WINDS HAVE RAISED THE SEAS IN THE GULF TO THE 
RANGE OF 11-18 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 TO 9 FT FROM 04N TO 14N BETWEEN 91W AND 
105W...ALSO FROM 04N TO 12N BETWEEN 105W AND 110W AND FROM 07N 
TO 19N BETWEEN 110W AND 124W. FRESH TRADE WINDS OVER THE WESTERN 
PORTION OF THIS AREA ARE ALSO HELPING TO MAINTAIN THE SEAS HIGH. 
MOST RECENT SEA SURFACE TEMPERATURE ANALYSIS REVEALS A COOL 
POCKET OF WATERS OVER A PORTION OF THE GULF AS WELL AS 
DOWNSTREAM FROM THE GULF TO NEAR 13N BETWEEN 94W-97W DUE TO 
UPWELLING EFFECTS.

HIGH PRES CENTERED OVER THE WESTERN GULF OF MEXICO WITH THE 
ASSOCIATED CULPRIT TIGHT PRES RIDGING STRETCHING SEWD ACROSS 
SOUTHEASTERN MEXICO IS FORECAST TO GRADUALLY WEAKEN THROUGH 
THU. THE GALE WINDS ARE EXPECTED TO DECREASE SLIGHTLY THROUGH 
TONIGHT...AND TO MINIMAL GALE FORCE BY EARLY THU AFTERNOON WITH 
SEAS SUBSIDING TO AROUND 14 FT AND TO 12 FT THU NIGHT. THE WINDS 
THEN INCREASE SOME THU NIGHT AND INTO EARLY FRI AS THE RIDGING 
BECOMES REINFORCED BY ANOTHER RIDGE THAT BUILDS SWD OVER THE FAR 
WESTERN GULF AND EASTERN MEXICO TERRAIN. SEAS IN THE GULF ARE 
FORECAST BY THE TAFB/NWPS GUIDANCE TO BUILD TO BACK TO 14 FT ON 
FRI.

GULF OF PAPAGAYO GALE WARNING...A TIGHTENING PRES GRADIENT 
BEHIND A SHEAR LINE IN THE WESTERN CARIBBEAN SEA N OF 10N WILL 
ALLOW FOR NE WINDS FUNNELING THROUGH THE GULF OF PAPAGAYO TO 
INCREASE TO MINIMAL GALE FORCE BY DAYBREAK THIS MORNING. WINDS 
WILL DIMINISH BELOW GALE FORCE DURING THE DAYTIME HOURS AND 
PULSE BACK TO GALE FORCE WITH THE ASSISTANCE OF DRAINAGE FLOW 
OFF THE MOUNTAINS IN THE LATE NIGHT AND EARLY MORNING HOURS 
THROUGH THU. SEAS IN AND NEAR THE GULF ARE FORECAST TO BUILD TO 
THE RANGE OF 8-12 FT THIS AFTERNOON AND THROUGH THU AFTERNOON 
BEFORE SUBSIDING TO AROUND 9 FT BY LATE THU. 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 MONSOON TROUGH AXIS EXTENDS FROM 02N78W TO 06N85W TO 05N94W 
WHERE SCATTEROMETER WINDS INDICATE A TRANSITION TO THE ITCZ AXIS 
EXTENDING TO 04N105W TO 07N114W TO 08N125W AND TO 08N140W. NO 
SIGNIFICANT DEEP CONVECTION IS NOTED ALONG OR NEAR THE MONSOON 
TROUGH AND ITCZ AXIS.

...DISCUSSION...                                                
A SLOW MOVING...NEGATIVELY TILTED UPPER LEVEL TROUGH IS THE MAIN 
FEATURE NOTED. IT STRETCHES FROM NEAR 32N130W TO 23N129W TO 
16N127W AND TO 09N122W. A SOUTHERLY JET STREAM BRANCH ON THE E 
SIDE OF THE TROUGH HAS MAX WINDS OF 80-100 KT. THIS IS HELPING 
TO ADVECT ABUNDANT UPPER MOISTURE...MAINLY IN THE FORM OF BROKEN 
TO OVERCAST MID AND UPPER CLOUDS NNE ACROSS SOUTHERN BAJA 
CALIFORNIA AND W CENTRAL MEXICO. UNDERNEATH THIS MOISTURE 
...SCATTERED SHOWERS AND ISOLATED TSTMS ARE POSSIBLE FROM 10N-
28N E OF THE TROUGH TO 110W. A SURFACE REFLECTION OF THIS TROUGH 
IS ANALYZED FROM 16N122W TO 11N123W. LIGHTNING DENSITY DATA 
INDICATES MULTIPLE LIGHTNING STRIKES WITHIN THE MENTIONED 
ACTIVITY FROM 13N-18N BETWEEN 119W-123W. THE DEEP LAYERED TROUGH 
WILL GRADUALLY SHIFT EASTWARD THROUGH THE NEXT 24N-48 HRS WITH 
THE CLOUDINESS AND MOISTURE TO ITS E GRADUALLY SPREADING OVER 
MUCH OF BAJA CALIFORNIA AND THE WESTERN PORTION OF MEXICO N OF 
ABOUT 18N. ELSEWHERE...HIGH PRES OF 1023 MB IS CENTERED NEAR 
35N124W MOVING NW 10 KT. A RIDGE EXTENDS FROM THE HIGH SE TO 
15N118W AND TO NEAR 18N116W. A WEAK TROUGH EXTENDS FROM 16N135W 
TO 15N138W. 

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 WITH SEAS TO 8 FT. THESE WINDS ARE 
FORECAST TO REACH AS FAR S AS 04N BY LATE TONIGHT WITH SEAS 
BUILDING TO 10 FT...AND LAST THROUGH WED AFTERNOON BEFORE 
SUBSIDING SLIGHTLY THU NIGHT.

GULF OF CALIFORNIA...THE PRES DIFFERENCE BETWEEN A TROUGH JUST W 
OF MEXICO ALONG 106W FROM 16N-19N AND HIGH PRES RIDGING JUST W 
OF BAJA CALIFORNIA WILL INDUCE FRESH TO STRONG NW-N WINDS  
OFFSHORE OF THE SE TIP OF THE BAJA CALIFORNIA PENINSULA BY 
DAYBREAK THIS MORNING WITH SEAS TO 8 FT. THE GRADIENT WILL 
WEAKEN ENOUGH TO ALLOW THESE WINDS TO DIMINISH TO 20 KT OR LESS 
BY EARLY THU AFTERNOON...THEN INCREASE AGAIN FROM 22N-25N 
BETWEEN 108W-110W BY LATE THU NIGHT AS RIDGING ACROSS THE 
EASTERN PACIFIC WATERS STRENGTHENS. 

$$ 
AGUIRRE