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Eastern Pacific Tropical Discussion

Active Tropical Systems Basin Outlooks Satellite
Eastern Pacific Basin Tropical Discussion
 
891 
AXPZ20 KNHC 251002
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1005 UTC SUN JAN 25 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...                                          
A GALE WARNING REMAINS IN EFFECT FOR THE GULF OF TEHUANTEPEC. N 
TO NE WINDS OF 30-40 KT ARE OCCURRING ACROSS THE GULF AS COLD 
DENSE AIR CONTINUES TO FUNNEL THROUGH THE CHIVELA PASS AND INTO 
THE GULF. MULTIPLE ASCAT DATA FROM LATE LAST NIGHT CLEARLY 
REVEALED THESE WINDS. SEA SURFACE TEMPERATURES REMAIN QUITE WARM 
WITH THE EXCEPTION OF A SMALL POCKET OF COOL UPWELLED WATER NEAR 
14N95W.  THE GALE WINDS HAVE GENERATED SEA STATE IN THE RANGE OF 
12-17 FT. N-NE WINDS OF 20-30 KT ARE WITHIN 60 NM EITHER SIDE OF 
A LINE FROM 16N95W TO 15N95W TO 13N97W N TO NE WINDS 20-30 KT 
WITH SEAS OF 9-14 FT. THE GALE WINDS ARE FORECAST TO DIMINISH TO 
JUST BELOW MINIMAL GALE FORCE BY THIS EVENING...THEN QUICKLY 
INCREASE TO GALE FORCE SPEEDS IN THE 30-40 KT RANGE OVERNIGHT 
TONIGHT AND INTO MON MORNING AS REINFORCING HIGH PRES ACROSS 
EASTERN MEXICO ALLOWS FOR ANOTHER SURGE OF COLD AIR TO SWEEP 
ACROSS THE GULF. THIS IS FORECAST TO BE A LONG DURATION GALE 
WIND EVENT LASTING WELL INTO THE UPCOMING WEEK.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...           
THE MONSOON TROUGH EXTENDS FROM 06N77W TO 07N85W TO 07N95W TO 
08N105W. THE ITCZ EXTENDS FROM 08N110W TO 06N125W TO 06N140W. 
SCATTERED MODERATE CONVECTION IS FROM 02N TO 04N BETWEEN 78W-
79W.

...DISCUSSION...                                                
ALOFT...A RIDGE/TROUGH/RIDGE PATTERN DOMINATES THE FORECAST AREA 
W OF 100W. A STRONG CUT-OFF LOW THAT RECENTLY FORMED JUST W OF 
BAJA CALIFORNIA IS CENTERED NEAR 24N118W...AND MOVING WESTWARD. 
A TROUGH EXTENDS FROM THE LOW SSW TO NEAR 12N126W. ABUNDANT 
MIDDLE TO UPPER LEVEL MOISTURE IS STREAMING ENE AHEAD OF THE 
TROUGH AXIS FURTHER ENHANCED BY A VERY ACTIVE SUBTROPICAL JET 
STREAM BRANCH THAT EXTENDS FROM 14N120W NEWD TO ACROSS FAR NW 
MEXICO. THE FLOW PATTERN TO THE SE OF THE LOW AND JET STREAM 
BRANCH IS IMPRESSIVELY DIFFLUENT THERE. AN ANTICYCLONE LOCATED 
OVER NORTHERN COLOMBIA AND WESTERN VENEZUELA EXTENDS A RIDGE 
WESTWARD ACROSS CENTRAL AMERICA AND SE MEXICO.

AT THE SURFACE...THE STRONG HIGH PRES THAT WAS LOCATED WELL N OF 
THE AREA DURING THE PREVIOUS DAYS IS WEAKENING AS A COLD FRONT 
APPROACHES FROM THE W. THIS HIGH PRES OF 1022 MB AS OF 06 UTC 
THIS MORNING EXTENDS A RIDGE SW TO COVER MOST OF THE DISCUSSION 
AREA N OF 20N. A WEAK SURFACE TROUGH THAT DEVELOPED FROM A 
FORMER UPPER LOW IS ANALYZED ALONG 118W FROM 11N TO 19N. 
SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN 180 NM E OF THE 
TROUGH...AND ARE BEING ENHANCED BY THE AFOREMENTIONED DIFFLUENCE 
ALOFT. ASCAT DATA FROM OVERNIGHT SHOWED NE-E WINDS IN THE 
MODERATE TO FRESH RANGE OVER THE SOUTHERN PERIPHERY OF THE RIDGE 
FROM 15N TO 21N W OF 120W. ANOTHER WEAK TROUGH IS ALONG A 
POSITION FROM 12N128W TO 08N133W. ISOLATED SHOWERS ARE POSSIBLE 
WITHIN 60 NM OF THE TROUGH. 
 
AN AREA OF LARGE LONG PERIOD NW SWELLS...ASSOCIATED WITH A COLD 
FRONT THAT IS APPROACHING THE NW PORTION OF THE AREA IS 
PROPAGATING SEWD THROUGH OVER THE WESTERN WATERS. THESE SWELLS 
ARE RESULTING IN MAX COMBINED SEAS OF UP TO 11 FT WITH PERIODS 
OF 16-17 SECONDS. THE COLD FRONT WILL ENTER THE FAR NW PORTION 
OF THE AREA THIS EVENING...REACH FROM NEAR 30N136W TO 21N140W BY 
MON EVENING...THEN BECOME STATIONARY INTO TUE AS WEAK LOW PRES 
OF 1010 FORMS ON THE FRONT NEAR 28N136W. THE PRES GRADIENT 
BETWEEN THE LOW AND HIGH PRES BUILDING EASTWARD JUST TO THE W OF 
140W WILL BRING FRESH TO STRONG N-NE WINDS W OF THE LOW AND 
FRONT N OF 25N BY LATE MON NIGHT WITH SEAS OF 9-10 FT. THE PRES 
GRADIENT WILL RELAX TUE ALLOWING FOR THESE WINDS TO DIMINISH TO 
15-20 KT WITH SEAS TO 8 FT IN LINGERING NW SWELLS. 
 
HIGH PRES OVER THE SOUTHWEST U.S. IN COMBINATION WITH A SURFACE 
TROUGH ACROSS NW MEXICO HAS TIGHTENED THE PRES GRADIENT IN THE 
EXTREME NORTHERN GULF OF CALIFORNIA WHERE NW-N WINDS ARE 
PRESENTLY IN THE FRESH TO STRONG RANGE WITH SEAS LESS THAN 8 FT. 
THESE WINDS ARE EXPECTED TO DIMINISH TO 20 KT OR LESS EARLY 
THIS AFTERNOON. 

GAP WINDS...                                                    
NE-E WINDS OF 20-25 KT FROM 09N TO 12N E OF 89W...AND TO THE 
GULF OF PAPAGAYO WILL DIMINISH TO 15-20 KT LATE THIS AFTERNOON 
AND THIS EVENING...AND THEN WILL MATERIALIZE AGAIN AT THE SAME 
SPEEDS LATE TONIGHT AND INTO MON MORNING THROUGH THE GULF OF 
PAPAGAYO AS HIGH PRES BUILDS ACROSS THE WESTERN CARIBBEAN. THESE 
WINDS ARE FORECAST TO LAST THROUGH TUE EVENING.

N WINDS OF 20-25 KT THROUGH THE GULF OF PANAMA WILL EXPAND S TO 
NEAR 04N AND BETWEEN 79W-81W BY LATE MON NIGHT.

THE PRES GRADIENT WILL REMAIN STRONG ENOUGH ACROSS THE WESTERN 
CARIBBEAN THROUGH AT LEAST TUE TO SUPPORT THESE GAP WIND EVENTS. 

$$ 
AGUIRRE