000
AXPZ20 KNHC 202106
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 UTC FRI MAR 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
            
THE MONSOON TROUGH EXTENDS FROM 06N88W TO 1013 MB LOW PRES NEAR 
03N93W TO 07N117W. THE ITCZ EXTENDS FROM 06N120W TO 03N128W TO 
BEYOND 05N140W. SCATTERED MODERATE CONVECTION WAS NOTED WITHIN 
120 NM SE SEMICIRCLE OF LOW PRES NEAR 03N93W.

...DISCUSSION... 

VERY TRANQUIL MARINE AND WEATHER CONDITIONS PERSIST ACROSS THE 
AREA THIS AFTERNOON. HIGH PRESSURE OF 1023 MB IS CENTERED NEAR 
26N136W WITH RIDGE EXTENDING SE TO NEAR 19N109W. A COLD FRONT 
HAS MOVED INTO THE FAR NW WATERS. THE PRES GRADIENT CURRENTLY 
PREVAILS BETWEEN THE HIGH AND LOW PRES IN THE VICINITY OF THE 
ITCZ IS SUPPORTING NE TRADEWINDS OF 15 TO 20 KT GENERALLY S OF 
23N AND W OF 117W. THE HIGH PRESSURE CENTER WILL SHIFT SLIGHTLY 
EASTWARD OVER THE UPCOMING WEEKEND WHILE BUILDING. THIS WILL 
TIGHTEN THE PRESSURE GRADIENT AND STRENGTHEN THE TRADEWINDS OVER 
THE FAR WESTERN WATERS N OF THE ITCZ BY SAT. A FRESH SET OF NW 
SWELLS WILL MOVE INTO THE FAR NW WATERS EARLY SUN WITH SEAS 
BUILDING TO NEAR 10 FT OVER THESE WATERS BY SUN AFTERNOON. THE 
COLD FRONT WILL MAKE EASTWARD PROGRESS ALONG 29-30N OVER THE 
WEEKEND AS IT WEAKENS...REACHING FROM 30N131W TO 27.5N140W BY 
SUNDAY EVENING...WHERE IT WILL DISSIPATE. 

OVER THE WATERS E OF 100W...THERE ARE NO ONGOING GAP WIND EVENTS 
THAT EXCEED 20 KT WINDS...WHILE SEAS ARE GENERALLY 6 FT OR LESS. 
GLOBAL MODELS INDICATE THAT NO SIGNIFICANT GAP WIND EVENTS ARE 
EXPECTED TO DEVELOP THROUGH THE WEEKEND. AS HAS BEEN MENTIONED 
THE PAST SEVERAL DISCUSSIONS...THIS IS THE FIRST TIME IN SEVERAL 
WEEKS THAT THERE IS NO GAP WIND ACTIVITY. OBSERVING THE SST 
SIGNALS VIA SATELLITE IMAGERY...THE PREDOMINANCE OF GAP WINDS 
FROM THE PAST SEVERAL WEEKS IS EVIDENT BY COLD PLUMES EXTENDING 
DOWNWIND OF THE GULFS OF TEHUANTEPEC...PAPAGAYO...AND PANAMA. 
THIS IS THE START OF THE TRANSITION PERIOD IN THE EPAC. WHILE 
CLIMATOLOGICALLY THE SST DOWNWIND OF THE GAPS TEND TO BE COOLER 
THAN THE SURROUNDING WATERS IN MARCH...THE LACK OF STRONG GAP 
WINDS DURING THE TRANSITION SEASON HELPS FOR SST'S TO REBOUND IN 
APRIL AND MAY IN ADVANCE OF THE EPAC TROPICAL CYCLONE SEASON. 
THIS INCREASE IN SST HELPS FOR THE GRADUAL DEVELOPMENT OF THE 
EASTERN PACIFIC MONSOON TROUGH WHICH HELPS PROVIDE A FAVORABLE 
BACKGROUND ENVIRONMENT FOR TROPICAL CYCLOGENESIS. 
 
$$
AL