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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 121603
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                        
1605 UTC THU FEB 12 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1500 UTC.               

...SPECIAL FEATURES... 

GULF OF TEHUANTEPEC GALE WARNING...NORTHERLY WINDS OF 30-45 KT
WITH SEAS UP TO 15-17 FT...ARE EXPECTED TO PERSIST THROUGH SUN
MORNING. THE AERIAL EXTENT OF THE STRONGEST WINDS WILL SLIGHTLY
INCREASE ON SAT AS HIGH PRES ACROSS THE WESTERN GULF OF MEXICO
WILL BE REINFORCING BY A STRONGER HIGH PRES BUILDING S ACROSS
THE CENTRAL PLAINS OF UNITED STATES. THE NORTHERLY WINDS WILL
GRADUALLY DIMINISH TO 20 KT OR LESS LATE MON MORNING. ANOTHER
GALE EVENT IS THEN POSSIBLE LATE MON NIGHT THROUGH EARLY NEXT
WEEK. THE RESULTANT SWELL CONTINUES TO PROPAGATE SE THROUGH
SW...MERGING WITH ENE SWELL GENERATED FROM THE GULF OF PAPAGAYO
GALE EVENT...MERGING WITH CROSS-EQUATORIAL SW SWELL AND ALSO
MERGING WITH LONG PERIOD NW SWELL. AS A RESULT...EXPECT AN AREA
OF COMBINED SEAS IN THE 8-12 FT RANGE S OF 13N-14N BETWEEN 92W-
93W AND 110W OVER THE NEXT 48 HOURS. SEE LATEST NWS HIGH SEAS
FORECAST UNDER AWIPS/ WMO HEADERS MIAHSFEP2/FZPN03 KNHC FOR MORE
DETAILS.

GULF OF PAPAGAYO GALE WARNING...MINIMAL GALE CONDITIONS ARE
EXPECTED PERSIST THROUGH THE MORNING HOURS. THE NARROW BAND OF
GALE CONDITIONS ARE SURROUNDED BY A LARGE AREA OF FRESH TO
STRONG NE WINDS...INCLUDING IN THE GULF OF FONSECA. SEAS ARE UP
TO 13 FT DOWNWIND OF THE GALE AREA. EXPECT THE NE FLOW TO
DIMINISH TO 20-25 KT DURING THE AFTERNOON AND EVENING HOURS AND
INCREASE AGAIN TO 25-30 KT AT NIGHT INTO THE EARLY MORNING HOURS
THROUGH THE FORECAST PERIOD. AS HIGH PRES BUILDS ACROSS THE
WESTERN CARIBBEAN ON SAT...EXPECT INCREASING WINDS TO 25-30 KT
ACROSS THE GULF OF FONSECA BY SAT NIGHT...THEN ACROSS THE GULF
OF PAPAGAYO BY EARLY SUN MORNING. SEE LATEST NWS HIGH SEAS
FORECAST UNDER AWIPS/WMO HEADERS MIAHSFEP2/FZPN03 KNHC FOR MORE
DETAILS.

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

THE ITCZ AXIS EXTENDS FROM 05N90W TO 04N100W TO 05N110W TO
07N120W TO 03N140W. SCATTERED MODERATE CONVECTION IS NOTED FROM
03N TO 06N BETWEEN 90W AND 108W...AND FROM 04N TO 06N BETWEEN
130W AND 135W. SCATTERED MODERATE ISOLATED STRONG CONVECTION CAN
BE FOUND FROM 09N TO 11N BETWEEN 115W AND 122W...AND FROM 04N TO
07N BETWEEN 124W AND 130W.

...DISCUSSION...

A STATIONARY FRONT IS OVER THE FAR NW CORNER OF THE AREA AND
EXTENDS FROM 30N136W TO 27N140W. SCATTERED MODERATE CONVECTION
IS SEEN WITHIN 60 NM AHEAD OF THE FRONT. A 1023 MB HIGH PRES
FALLOWS THE FRONT AND IS CENTERED NEAR 30N146W. THE FRONT WILL
GRADUALLY DISSIPATE THROUGH THIS EVENING. THE HIGH PRES WILL
MOVE NE TO A POSITION NEAR 35N134W AND GRADUALLY STRENGTHEN.
THIS WILL INCREASE THE PRES GRADIENT ACROSS THE FORECAST WATERS
W OF 120W THIS WEEKEND. AS A RESULT...EXPECT A LARGE AREA OF
FRESH TO STRONG TRADES PARTICULARLY N OF THE ITCZ W OF 120W. 

MODEL GUIDANCE SUGGESTS THE DEVELOPMENT OF ONE OR TWO TROUGHS N
OF THE ITCZ W OF 120W THROUGH SAT NIGHT. WHILE THERE MAYBE AN
ISSUE WITH CONVECTIVE FEEDBACK...THE DETERMINISTIC RUNS OF THE
GFS...ECMWF...AND UKMET ALL INCREASE WINDS TO GALE FORCE WITH A
TROUGH NEAR OR ALONG 126W BY SAT NIGHT...WHILE GEFS 34 KT
PROBABILITIES ARE GREATER THAN 20 PERCENT. SREF PACIFIC 34 KT
PROBABILITIES ARE 10-15 PERCENT. FOR NOW WILL CAP WINDS
ASSOCIATED WITH THIS FEATURE AT 30 KT...ALTHOUGH THIS WILL NEED
TO BE MONITORED AS CONDITIONS PROGRESS.

LARGE NW SWELLS...WITH WAVE PERIODS OF 21-22 SECONDS...CONTINUE
TO PROPAGATE ACROSS MOST OF THE WATERS W OF 115W WITH SEAS UP TO
17-18 FT NEAR 30N140W. THIS SWELL EVENT WILL CONTINUE TO
PROPAGATE TO THE E-SE...REACHING THE COAST OF THE BAJA
CALIFORNIA THROUGH THIS EVENING...AND THE REVILLAGIGEDO AND LAS
TRES MARIAS ISLANDS TONIGHT. EXPECT ROUGH AND HAZARDOUS SURF
CONDITIONS AS THE LEADING EDGE OF THE SWELL TRAIN REACHES SHORE.
SEAS OF 8 FT OR GREATER ASSOCIATED WITH THIS SWELL WILL REACH
ALL THE WAY TO 110W BY SAT MORNING.

GULF OF PANAMA...A TIGHT PRES GRADIENT WILL REMAIN IN PLACE
ACROSS THE REGION DUE TO HIGH PRES RIDGING ACROSS THE WESTERN
CARIBBEAN AND LOW PRES OVER NW COLOMBIA. THIS SETUP WILL
CONTINUE TO SUPPORT FRESH TO STRONG NORTHERLY FLOW DOWNWIND OF
THE GULF OF PANAMA THROUGH THE UPCOMING WEEKEND...OCCASIONALLY
INCREASING TO 30 KT NEAR OR JUST S OF THE AZUERO PENINSULA
DURING THE OVERNIGHT HOURS. SEAS WILL BUILD TO 7-10 FT ACROSS
THIS AREA AS A RESULT.

GULF OF CALIFORNIA...MAINLY MODERATE NORTHERLY FLOW AND 1-3 FT
SEAS WILL PREVAIL THROUGH SUN MORNING WITH SEAS OF 3-5 FT NEAR
THE ENTRANCE.

$$
GR