000
AXPZ20 KNHC 200306
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
0405 UTC WED MAY 20 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 
0315 UTC.
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 
A MONSOONAL CIRCULATION IS NOT CURRENTLY EVIDENT ACROSS THE 
REGION. THE ITCZ AXIS EXTENDS FROM 07N90W TO 09.5N100W TO 
07N110W AND FROM 07N120W TO 07N130W. SCATTERED MODERATE 
CONVECTION IS NOTED FROM 02N TO 10N E OF 95W...AND FROM 02N TO 
12N BETWEEN 110W AND 130W. 

A TROUGH EXTENDS FROM 07N130W TO 04N140W. SCATTERED MODERATE TO 
ISOLATED STRONG CONVECTION IS NOTED FROM 04N TO 07N BETWEEN 134W 
AND 138W.

...DISCUSSION...                                           

E OF 120W... 
WEAK SURFACE HIGH PRES NEAR 30N127W IS SUPPORTING 20KT NORTHERLY 
WINDS ALONG THE COAST OF BAJA CALIFORNIA NORTE THIS EVENING. 
THESE FUNNELING WINDS WILL DIMINISH AND THE HIGH PRES WILL 
WEAKEN THROUGH WED AS A PAIR OF MID TO UPPER LEVEL SHORT WAVE 
TROUGHS WILL MOVE EASTWARD ACROSS THE WATERS N OF 20N THROUGH 
THURSDAY...ASSOCIATED WITH AN UPPER LOW MOVING FROM THE NE 
PACIFIC INTO SOUTHERN CALIFORNIA. GLOBAL MODELS INDICATE A 
SURFACE LOW PRES FORMING OVER SOUTHERN CALIFORNIA AND THE 
NORTHERN GULF OF CALIFORNIA BY LATE WED...RESULTING IN FRESH TO 
STRONG SW FLOW ACROSS THE FAR NORTHERN REACHES OF THE GULF OF 
CALIFORNIA WED NIGHT AND EARLY THU. SEAS WILL NOT BUILD ABOVE 4 
FT DUE TO LIMITED FETCH IN THE NORTHERN GULF OF CALIFORNIA. 
LOOKING AHEAD...THE LOW PRES WILL DISSIPATE THROUGH FRI AS THE 
SUPPORTING UPPER LOW WEAKENS AND SHIFTS EAST. RIDGING WILL BUILD 
WEST OF THE AREA IN THE WAKE OF THE UPPER LOW ALLOWING 20 KT 
NORTHERLY FLOW ALONG THE BAJA CALIFORNIA COAST THROUGH THE 
WEEKEND WITH SEAS 5 TO 7 FT.

FARTHER SOUTH...AN UPPER LOW CENTERED NEAR 06N97W IS SUPPORTING 
A BROAD AREA OF SHOWERS AND THUNDERSTORMS FROM 02N TO 10N MAINLY 
E OF 105W. THE UPPER TROUGH WILL WEAKEN THROUGH THE REMAINDER OF 
THE WEEK...BUT HIGH LEVELS OF DEEP LAYER MOISTURE AND MODEST LOW 
LEVEL CONVERGENCE ALONG THE ITCZ WILL MAINTAIN SCATTERED 
CONVECTION THROUGH FRI S OF 12N E OF 120W. 

GAP WIND FLOW INTO THE GULF OF PAPAGAYO WILL BRIEFLY INCREASE TO 
15 TO 20 KT TONIGHT THEN BECOME LIGHT TO MODERATE WED MORNING.

W OF 120W...
EVIDENCE OF A WEAK SURFACE TROUGH WAS NOTED IN EARLIER 
SCATTEROMETER SATELLITE DATA ALONG THE ITCZ NEAR 135W. THIS 
FEATURE IS EXPECTED TO PERSIST AS IT MOVES WEST OF AN UPPER 
RIDGE...CROSSING 140W BY FRI. A SECOND SURFACE TROUGH IS NOTED 
NEAR 115W...ASSOCIATED WITH A PERSISTENT LOW TO MID LEVEL WAVE 
AND RECEIVING SOME ENHANCEMENT FROM AN UPPER TROUGH CENTERED 
OVER THE DEEP TROPICS S OF 15N ALONG 125W. THIS SURFACE TROUGH 
WILL ALSO PERSIST AS IT SHIFTS WESTWARD REACHING 125W THROUGH 
EARLY FRI. 

MEANWHILE 1021 MB SURFACE HIGH PRES IS CENTERED N OF THE AREA 
NEAR 31N127W. THIS WILL WEAKEN THROUGH EARLY WED AS A PAIR OF 
MID/UPPER TROUGHS MIGRATE EASTWARD OVER THE REGION N OF 20N. 
RIDGING BEHIND THESE TROUGHS WILL ALLOW THE SUBTROPICAL RIDGE TO 
BUILD THU AND FRI...ALLOWING TRADE WIND TO INCREASE BETWEEN THE 
RIDGE AND THE TROUGHING TO THE SOUTH BY LATE FRI. 
 
SOUTHERLY SWELL WITH WAVE HEIGHTS OF 8 TO 9 FT AND PERIODS OF 15 
TO 16 SECONDS WILL MOVE ACROSS THE EQUATOR IN THE WATERS MAINLY 
W OF THE GALAPAGOS...REACHING AS FAR N AS 02N THROUGH THU BEFORE 
DECAYING BELOW 8 FT FRI. HOWEVER THE LONG PERIOD SWELL WILL 
REACH THE COASTLINE OF CENTRAL AMERICA AND SOUTHERN MEXICO BY 
LATE FRI AND SAT POSSIBLY PRESENTING LARGE AND DANGER SURFACE 
THROUGH THE UPCOMING WEEKEND.
 
$$
CHRISTENSEN