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Eastern Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 220218
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
0405 UTC FRI MAY 22 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0215 UTC.

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

THE ITCZ AXIS WAS ANALYZED FROM 08N93W TO 06N103W TO 09N114W. A 
TROUGH WAS ANALYZED FROM 12N117W TO LOW PRES NEAR 08N121W 1008 
MB TO 02N124W. THE MONSOON TROUGH AXIS WAS ANALYZED FROM 06N124W 
TO 06N130W TO LOW PRES NEAR 08N137W 1009 MB. SCATTERED MODERATE 
TO STRONG CONVECTION WAS OBSERVED FROM 05N TO 13N BETWEEN 115W 
AND 127W. 

...DISCUSSION...                                           

N OF 15N E OF 120W...A PAIR OF UPPER SHORT WAVE TROUGHS WILL 
MOVE ACROSS SOUTHERN CALIFORNIA AND THE NORTHERN PORTION OF BAJA 
CALIFORNIA NORTE AND THE GULF OF CALIFORNIA THROUGH LATE 
FRI...SUPPORTING 1008 MB LOW PRESSURE CENTERED OVER THE 
CALIFORNIA/ARIZONA BORDER. THIS HAS BEEN THE IMPETUS FOR 20 KT 
SW WINDS OVER THE FAR NORTHERN GULF OF CALIFORNIA AS NOTED IN 
EARLIER SCATTEROMETER SATELLITE IMAGERY. WINDS TO 25 KT ARE 
LIKELY IN THIS AREA THROUGH TONIGHT...WITH WINDS DIMINISHING 
EARLY FRI AS THE LOW PRESSURE WEAKENS AND SHIFTS NE OF THE AREA. 
MEANWHILE THE SUBTROPICAL RIDGE WILL BUILD ACROSS THE EASTERN 
PACIFIC WATERS N OF 20N IN THE WAKE OF THE UPPER TROUGH. A 17 
UTC SCATTEROMETER PASS INDICATED A SURFACE TROUGH RELATED TO THE 
UPPER SHORT WAVE TROUGHS DENTING THE RIDGE...REACHING FROM 
27N120W TO 27N115W. THIS FEATURE WILL ALLOW FOR GENTLE TO 
MODERATE BREEZES FARTHER OFFSHORE OF THE BAJA COAST NORTH OF 
PUNTA EUGENIA THROUGH TONIGHT. THE TROUGH WILL DISSIPATE THROUGH 
LATE SAT...ALLOWING A SLIGHT INCREASE IN NORTHERLY WINDS ALONG 
THE BAJA COAST AS THE RIDGE BUILDS EASTWARD. 

LOOKING AHEAD...GLOBAL MODELS ARE INDICATING 15 TO 20 
KT NORTHERLY WINDS AND SEAS 6 TO 7 FT OFF THE LENGTH OF THE BAJA 
COAST LATE FRIDAY THROUGH SUNDAY. 

S OF 15N E OF 110W...1010 MB LOW PRESSURE WAS EVIDENT IN A 15 
UTC SCATTEROMETER SATELLITE PASS OFF THE COAST OF COSTA RICA 
NEAR 09N85W. THIS MAY BE RELATED TO 15 TO 20 KT PLUME OF GAP 
WINDS THROUGH THE GULF OF PAPAGAYO JUST TO THE NORTH...AND 
PERHAPS A WEAK TROPICAL WAVE PASSING WEST IN THE LOWER TO MID 
LEVELS OF THE ATMOSPHERE. SURROUNDING CONVECTION IS RELATED TO 
DIVERGENCE ALOFT BETWEEN UPPER RIDGING TO THE EAST AND AN UPPER 
TROUGH TO THE NW OFF THE GUATEMALAN COAST. THE FRESH GAP FLOW 
THROUGH PAPAGAYO HAS DIMINISHED FOR NOW BUT WILL LIKELY RETURN 
OVERNIGHT THE NEXT COUPLE OF NIGHTS. GLOBAL MODELS INITIALIZE 
WELL WITH THE LOW PRESSURE...AND SHOW IT WEAKENING TO A SURFACE 
TROUGH THROUGH FRI AS IT DRIFTS WEST. CONVECTION WILL BE ACTIVE 
OVERNIGHT ALONG THE COASTLINE AND FARTHER WEST TO 100W NEAR THE 
ITCZ ALONG ROUGHLY 07N TO 10N. PERSISTENT SUBSIDENT NORTHERLY 
FLOW ALOFT IS LIMITING CONVECTIVE DEVELOPMENT ALONG THE ITCZ 
BETWEEN 100W AND 110W. 

VARIOUS WAVE MODELS CONTINUE TO INDICATE LONGER PERIOD SOUTHERLY 
SWELL WITH HEIGHTS OF 8 TO 9 FT CROSSING THE EQUATOR TONIGHT 
REACHING AS FAR NORTH AS 03N THROUGH FRIDAY WEST OF THE 
GALAPAGOS BEFORE DECAYING BELOW 8 FT SAT. SEAS OF 5 TO 7 FT WILL 
REACH THE CENTRAL AMERICAN AND SOUTHERN MEXICAN COASTS SATURDAY 
WITH THE POTENTIAL FOR LARGE AND DANGEROUS SURF CONDITIONS. 

LOOKING AHEAD...GLOBAL MODELS ARE IN LOOSE AGREEMENT SHOWING A 
BROAD LOW BECOMING MORE ORGANIZED EARLY NEXT WEEK NEAR ROUGHLY 
10N100W...ALTHOUGH THERE REMAINS MUCH DISAGREEMENT REGARDING 
POSITION...TIMING AND STRENGTH. THE MAIN IMPACTS WILL BE 
INCREASE EASTERLY FLOW FROM 10N TO 15N EAST OF 100W...SEAS TO AT 
LEAST 7 FT...AND INCREASED SHOWERS AND THUNDERSTORMS.

ELSEWHERE...CONVECTION REMAINS VERY ACTIVE ACROSS THE DEEP 
TROPICS SOUTH OF 12N WEST OF 110W...WITH AN ELONGATED TROUGH 
FROM 12N117W TO 02N123W AND BROAD 1009 MB LOW PRESSURE CENTERED 
NEAR 07N136W. THESE SYSTEMS REMAIN FAIRLY DISORGANIZED FOR 
NOW...BUT GLOBAL MODELS INDICATE SLOW DEVELOPMENT THROUGH 48 
HOURS. FOR NOW THE MAIN MARINE CONCERN OUTSIDE THUNDERSTORM 
ACTIVITY IS INCREASED TRADE WIND FLOW BETWEEN THE DEVELOPING LOW 
PRESSURE AREAS AND THE SUBTROPICAL RIDGE BUILDING TO THE NORTH. 
VARIOUS SHIP AND BUOY OBSERVATIONS ALONG WITH RECENT 
SCATTEROMETER AND ALTIMETER SATELLITE DATA INDICATE AREAS OF 
TRADE WINDS 20 TO 25 KT WITH SEAS TO 8 FT...SLIGHTLY ABOVE 
GUIDANCE INITIALIZATIONS. THE MARINE FORECAST REMAINS SLIGHTLY 
ABOVE GUIDANCE ACCORDINGLY INTO FRIDAY...ALTHOUGH SHIFTS TO A 
MORE CONSERVATIVE SOLUTION FAVORING THE ECMWF OVER THE GFS INTO 
SATURDAY CONCERNING DEVELOPMENT OF LOW PRESSURE ALONG THE TROUGH 
NEAR 120W.

LOOKING AHEAD...TROPICAL CYCLONE DEVELOPMENT IS POSSIBLE AFTER 
48 HOURS ESPECIALLY CONCERNING LOW PRESSURE FORMING ALONG THE 
TROUGH AS IT SHIFTS WESTWARD.

$$
CHRISTENSEN


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Page last modified: Friday, 22-May-2015 02:18:25 UTC