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Eastern Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 281000
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1005 UTC TUE JUL 28 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 
0900 UTC. 

...SPECIAL FEATURE...                                            

TROPICAL DEPRESSION EIGHT-E WAS NEAR 16.2N 128.0W 1007 MB AT 
0900 UTC JUL 28 MOVING WNW OR 290 DEG AT 11 KT. MAXIMUM 
SUSTAINED WINDS 30 KT GUSTS 40 KT. UPPER LEVEL NW WIND SHEAR HAS 
DECREASED SLIGHTLY IN THE PAST FEW HOURS...AND DEEP CONVECTION 
HAS INCREASED ACROSS THE CENTER...WITH NUMEROUS MODERATE TO 
STRONG CONVECTION OCCURRING WITHIN 90 NM E AND 30 NM W 
SEMICIRCLES...WHILE BANDS OF SCATTERED MODERATE TO STRONG 
CONVECTION WERE ELSEWHERE WITHIN 300 NM ACROSS THE E SEMICIRCLE. 
THE SYSTEM IS EXPECTED TO STRENGTHEN SLIGHTLY TODAY AS IT 
CONTINUES MOVING W-NW...BECOMING A TROPICAL STORM...THEN  WEAKEN 
BACK A TROPICAL DEPRESSION ON WED. SEE THE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMEP3/WTPZ23 KNHC 
FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE WAS INVOF 82W-83W MOVING W NEAR 10 KT. THE NORTH 
PORTION OF THIS WAVE HAS SHIFTED MORE W-NW ACROSS CENTRAL 
AMERICA. CONVECTION IN THIS AREA WAS ALSO ASSOCIATED WITH THE 
MONSOON TROUGH AND A TUTT OVERHEAD ALONG 04N-05N...AND IS 
DESCRIBED BELOW.

A TROPICAL WAVE WAS INVOF 109W-111W MOVING W 15-20 KT. ISOLATED 
TO SCATTERED MODERATE TO STRONG CONVECTION WAS WITHIN 60 NM E 
AND 180 NM W OF THE WAVE FROM 04N-13N. 

BROAD LOW PRES NEAR 08.5N116.5W 1008 MB WAS EMBEDDED WITHIN THE 
MONSOON TROUGH...AND ALSO ASSOCIATED WITH A TROPICAL 
WAVE...MOVING W 15-20 KT. BANDS AND LINES OF SCATTERED MODERATE 
TO STRONG CONVECTION WERE OCCURRING AROUND THE PERIPHERY OF THIS 
CIRCULATION...WITHIN 270 NM ACROSS THE NE AND 300 NM SW 
SEMICIRCLES. THIS LOW PRES AREA HAS THE POTENTIAL TO GRADUALLY 
BECOME BETTER ORGANIZED OVER THE NEXT SEVERAL DAYS AS IT 
CONTINUES MOVING W.

A TROPICAL WAVE WAS INVOF 132W-135W MOVING W AROUND 15 KT. 
SCATTERED MODERATE TO STRONG CONVECTION WAS FROM 09N TO 14N 
BETWEEN 133W AND 139W.  

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

THE MONSOON TROUGH EXTENDS FROM 06.5N78W TO 09N85W TO 07.5N94W 
TO LOW PRES NEAR 08.5N116.5W TO 10N120W...WHERE IT IS 
FRACTURED...THEN RESUMES FROM 13N129W TO BEYOND LOW PRES NEAR 
10N140.5W. SCATTERED MODERATE TO STRONG CONVECTION WITHIN 120 NM 
N AND 300 NM S OF TROUGH E OF 90W...AND WITHIN 120 NM N AND 240 
NM S OF TROUGH BETWEEN 90W AND 112W. 

...DISCUSSION...

1029 MB HIGH PRESSURE IS ANALYZED WELL N OF THE AREA NEAR 
44N136W AND EXTENDS A RIDGE AXIS SE THROUGH 30N130W TO 
19N114W...AND OVER THE WATERS OFF THE BAJA CALIFORNIA PENINSULA. 
DEEP-LAYERED TROUGHING OVER THE SW UNITED STATES AND A MID-LEVEL 
CYCLONE MEANDERING ACROSS S CENTRAL BAJA CALIFORNIA HAVE FORCED 
MORE TROUGHING AT THE SURFACE. THIS INCREASED THE PRESSURE 
GRADIENT AND THE WINDS OFFSHORE OF THE BAJA CALIFORNIA PENINSULA 
LATE THIS AFTERNOON AND EVENING...AND HAS BEGUN TO DIMINISH 
SLIGHTLY EARLY THIS MORNING. THESE MODERATE TO FRESH NW WINDS ARE 
FORECAST TO CONTINUE TO DIMINISH THIS MORNING TO 20 KT OR LESS. 
THE PRESSURE GRADIENT WILL SLACKEN FURTHER DURING THE DAY 
TODAY WHEN THE AFOREMENTIONED TROUGHING WEAKENS. 

THE PRESSURE GRADIENT BETWEEN THE SUBTROPICAL RIDGE AND LOWER 
PRESSURE ALONG THE MONSOON TROUGH HAS BROUGHT MODERATE TO FRESH 
TRADE WINDS TO THE AREA PRIMARILY N OF 10N W OF 125W. THE AREA 
OF STRONGEST TRADES CLOSEST TO THE TYPICAL CONVERGENCE ZONE S OF 
20N IS FORECAST TO SHIFT W OF THE AREA OVER THE NEXT TWO DAYS AS 
TROPICAL DEPRESSION EIGHT-E MOVES W-NW...SHIFTING THE STRONGEST 
PRESSURE GRADIENT W. SEAS WERE 7-9 FT IN NE WIND WAVES AND MIXED 
SE AND SW SWELL PRIMARILY FROM 07N TO 16N W OF 134W. THESE 
MARINE CONDITIONS SHOULD SUBSIDE BELOW 8 FT BY THIS AFTERNOON.

GAP WINDS...                                                    
GULF OF PAPAGAYO...ENHANCED TRADE WINDS FROM THE SOUTHERN 
CARIBBEAN ARE BLOWING ACROSS CENTRAL AMERICA AND FUNNELING 
THROUGH MOUNTAINOUS PASSAGES CENTRAL AMERICA. OFFSHORE NE WINDS 
ARE BRIEFLY PULSING TO 20-25 KT WITH THE ASSISTANCE OF NOCTURNAL 
DRAINAGE FLOW ACROSS AND DOWNWIND OF PAPAGAYO EARLY THIS MORNING 
AND WILL DO SO AGAIN TONIGHT...WITH SEAS BUILDING TO 9 FT.

$$ 
STRIPLING

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Page last modified: Tuesday, 28-Jul-2015 10:01:02 UTC