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Eastern Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 291603
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1605 UTC WED JUL 29 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 FEATURE...                                            

THE CENTER OF TROPICAL DEPRESSION EIGHT-E AT 29/1500 UTC IS NEAR 
17.0N 133.6W. THE MINIMUM CENTRAL PRESSURE IS 1007 MB. THE 
DEPRESSION IS MOVING WESTWARD...OR 270 DEG...11 KNOTS. THE 
MAXIMUM SUSTAINED WIND SPEEDS ARE 30 KNOTS WITH GUSTS TO 40 
KNOTS. CONVECTIVE PRECIPITATION...NUMEROUS STRONG FROM 14N TO 
17N BETWEEN 132W AND 134W. SCATTERED MODERATE TO ISOLATED STRONG 
FROM 17N TO 18N BETWEEN 132W AND 134W. PLEASE READ THE LATEST 
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMEP3/WTPZ23 
KNHC FOR MORE DETAILS.

A 1006 MB LOW PRESSURE CENTER IS NEAR 07N121W. THIS LOW CENTER 
IS EMBEDDED IN THE MONSOON TROUGH...AND IT CONTINUES TO MOVE 
WESTWARD 15 KNOTS. CONVECTIVE PRECIPITATION...SCATTERED MODERATE 
TO ISOLATED STRONG IN BROKEN BANDS...FROM 02N TO 13N BETWEEN 
120W AND 130W. ISOLATED MODERATE TO LOCALLY STRONG FROM 06N TO 
13N BETWEEN 110W AND 120W. THE LOW WILL CONTINUE TO MOVE WEST-
NORTHWESTWARD DURING THE NEXT SEVERAL DAYS. IT IS EXPECTED TO 
IMPROVE GRADUALLY IN ITS ORGANIZATION. THIS FEATURE HAS A MEDIUM 
CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

...TROPICAL WAVES...

A TROPICAL WAVE IS 83W FROM 20N SOUTHWARD. THE WAVE IS MOVING 
THROUGH THE WESTERNMOST SECTIONS OF THE CARIBBEAN SEA... 
APPROACHING CENTRAL AMERICA. CONVECTIVE PRECIPITATION...PLEASE 
REFER TO THE MONSOON TROUGH/ITCZ SECTION FOR INFORMATION ABOUT 
THE CONVECTIVE PRECIPITATION.

A TROPICAL WAVE IS ALONG 94W/95W FROM 17N IN THE ISTHMUS OF 
TEHUANTEPEC OF SOUTHERN MEXICO SOUTHWARD. THE WAVE IS MOVING 
WESTWARD 15 KNOTS. THE WAVE IS INTERACTING WITH AN UPPER LEVEL 
CYCLONIC CIRCULATION CENTER THAT IS ALONG THE SOUTHEASTERN COAST 
OF CENTRAL MEXICO. 

A TROPICAL WAVE IS ALONG 118W/119W FROM 17N SOUTHWARD...MOVING 
WESTWARD 15 KNOTS. CONVECTIVE PRECIPITATION...THE PRECIPITATION 
IS BECOMING ABSORBED INTO THE EASTERN PERIPHERY OF A 1008 MB LOW 
PRESSURE CENTER THAT IS NEAR 07N121W. IT IS LIKELY THAT THIS 
WAVE WILL INTERACT WITH AND/OR BECOME ABSORBED INTO THE 1008 
MB LOW CENTER DURING THE NEXT 12 TO 24 HOURS. 

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

THE MONSOON TROUGH IS ALONG 09N94W 07N88W 07N92W 07N105W 
09N115W. CONVECTIVE PRECIPITATION...WIDELY SCATTERED TO 
SCATTERED MODERATE TO ISOLATED STRONG FROM 02N TO 12N FROM 110W 
EASTWARD. 

...DISCUSSION...

A SURFACE RIDGE PASSES THROUGH 32N139W TO 26N126W TO 20N111W. 
THE SURFACE PRESSURE GRADIENT BETWEEN THE RIDGE AND THE TYPICAL 
TROUGH THAT IS SEEN ALONG BAJA CALIFORNIA IS HELPING TO INDUCE 
NW WINDS AROUND 15 KT WITHIN ABOUT 180 NM W OF THE BAJA 
CALIFORNIA PENINSULA WITH RESULTANT SEAS OF 6-7 FT. THE GRADIENT 
IS FORECAST TO RELAX ENOUGH THIS AFTERNOON TO ALLOW THESE WINDS 
TO DIMINISH TO 10-15 KT WITH SEAS LOWERING TO AROUND 5-6 FT.

THE SURFACE PRESSURE GRADIENT THAT EXISTS BETWEEN THE 
SUBTROPICAL RIDGE AND LOWER SURFACE PRESSURES THAT ARE ACROSS 
THE DEEP TROPICS IS ALLOWING FOR MODERATE BUT WEAKENING TRADE 
WINDS TO PREVAIL IN THE WESTERN PART OF THE AREA FROM 14N  TO 
28N AND TO THE WEST OF 130W. THESE WINDS WILL BE REPLACED BY 
STRONGER WINDS ON THE PERIPHERY OF TROPICAL DEPRESSION EIGHT AS 
IT MOVES WEST-NORTHWESTWARD. THE PRESENT SEAS OF 6 TO 8 FEET  
ARE EXPECTED TO BUILD TO 6 TO 9 FEET WITH THE APPROACH OF THE 
TROPICAL DEPRESSION...AND THEN FRESHEN MORE ON THURSDAY AND 
FRIDAY. THE 1006 MB LOW PRESSURE CENTER ALSO IS FORECAST TO MOVE 
WESTWARD THROUGH THE TROPICS AND INCREASE THE SURFACE PRESSURE 
GRADIENT TO THE NORTH. 

GAP WINDS...                                                    
THE GULF OF PAPAGAYO...STRONG TRADE WINDS FROM THE SOUTHERN 
CARIBBEAN CONTINUE TO FUNNEL ACROSS THE HIGHER TERRAIN OF 
CENTRAL AMERICA AND SPILL ACROSS THE PACIFIC COASTAL WATERS THAT 
ARE TO THE EAST OF 90W. THE MOST RECENT SCATTEROMETER DATA 
SHOWED NORTHEAST-TO-EAST WINDS 20-25 KNOTS OFF OF THE NICARAGUAN 
COAST DOWNSTREAM OF LAKES NICARAGUA AND MANAGUA...EXTENDING 
WESTWARD TO NEAR 89W...WHERE MAX SEAS WERE 8 FEET. THE WINDS IN 
THIS AREA WILL DIMINISH TO 15 TO 20 KNOTS BY THE AFTERNOON...AND 
THEN INCREASE AGAIN TONIGHT AND LIKELY ON FRIDAY NIGHT...AS 
NOCTURNAL DRAINAGE FLOW ALLOWS THE WIND SPEEDS TO REACH THE 20 
TO 25 KNOT RANGE AGAIN.

A NARROW PLUME OF NORTHERLY WINDS IN THE RANGE OF 20 TO 25 KNOTS 
WAS MOVING THROUGH THE GULF OF TEHUANTEPEC EARLIER THIS 
MORNING...AHEAD OF THE TROPICAL WAVE THAT IS MOVING THROUGH THE 
WESTERN PARTS OF THE CARIBBEAN SEA. THESE WINDS ALSO WILL PULSE 
TO A PEAK OF 20 TO 25 KNOTS OVERNIGHT DURING THE MORNING HOURS 
FOR THE NEXT 2 DAYS...BEFORE DIMINISHING TO 15 TO 20 KNOTS EACH 
AFTERNOON.

$$ 
MT


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Page last modified: Wednesday, 29-Jul-2015 16:03:46 UTC