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Eastern Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 292130
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC. 

...SPECIAL FEATURES...                                           

THE CENTER OF TROPICAL DEPRESSION EIGHT-E AT 29/2100 UTC IS NEAR 
16.6N 135.6W. THE MINIMUM CENTRAL PRESSURE IS 1007 MB. THE 
DEPRESSION IS MOVING WESTWARD...OR 265 DEG...14 KNOTS. THE 
MAXIMUM SUSTAINED WIND SPEEDS ARE 30 KNOTS WITH GUSTS TO 40 
KNOTS. CURRENTLY SCATTERED MODERATE ISOLATED STRONG CONVECTION 
IS WITHIN 180 NM NE SEMICIRCLE. THIS CONVECTION IS WEAKENING 
WITH TIME AND THE DEPRESSION IS EXPECTED TO DISSIPATE WITHIN THE 
NEXT 36 TO 48 HOURS AS IT CROSSES 140W. 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 08N123W. THIS LOW CENTER 
IS BECOMING BETTER ORGANIZED WITH INCREASED BANDING NOTED IN THE 
CONVECTIVE CLOUDS. CURRENTLY SCATTERED MODERATE TO STRONG 
CONVECTION IS NOTED WITHIN 150 NM IN THE W SEMICIRCLE. A LARGER 
AREA OF SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS 
ELSEWHERE WITHIN 360 NM NE AND 210 NM SW SEMICIRCLES. HIGH 
CONFIDENCE IN THE MODEL FORECASTS NECESSITATED THE ISSUANCE OF  
STORM WARNINGS FOR THE HIGH SEAS IN ASSOCIATION WITH THIS LOW. 
TROPICAL CYCLONE MARINE WARNINGS WILL LIKELY BE ISSUED LATER 
TONIGHT IN ASSOCIATION WITH THIS SYSTEM. THIS FEATURE HAS A HIGH 
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 96W 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. THIS INTERACTION WAS PRODUCING SCATTERED 
MODERATE TO STRONG CONVECTION WITHIN 180 NM W OF THE WAVE AXIS 
FROM 09N TO 14N.  

A TROPICAL WAVE EARLIER ALONG 118W/119W HAS BECOME ABSORBED INTO 
THE EASTERN PERIPHERY OF THE 1007 MB LOW PRESSURE NOTED IN THE 
SPECIAL FEATURES SECTION ABOVE. 

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

MONSOON TROUGH AXIS FROM 10N85W TO 07N100W TO 09N115W. SCATTERED 
MODERATE ISOLATED STRONG WITHIN 240 NM EITHER SIDE OF THE AXIS 
BETWEEN 82W AND 105W.  

...DISCUSSION...

A SURFACE RIDGE PASSES THROUGH 32N139W TO 26N126W TO 20N111W. 
THE SLACKENED PRESSURE GRADIENT BETWEEN THE RIDGE AND THE 
TYPICAL TROUGH THAT IS SEEN ALONG BAJA CALIFORNIA HAS ALLOWED NW 
WINDS TO SUBSIDE TO DAY TO THE 10-15 KT RANGE WITHIN ABOUT 180 
NM W OF THE BAJA CALIFORNIA PENINSULA WITH RESULTANT SEAS OF 5 
TO 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 WEAKENING 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 TO NEAR GALE FORCE 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 WINDS IN THIS AREA WILL 
HAVE DIMINISHED TO 15 TO 20 KNOTS THIS 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 
IS FORECAST TO MOVE THROUGH THE GULF OF TEHUANTEPEC LATER 
TONIGHT. THESE WINDS ALSO WILL PULSE AGAIN TO 20 TO 25 KNOTS 
OVERNIGHT THU INTO THE MORNING HOURS ON FRI.

$$ 
COBB

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Page last modified: Wednesday, 29-Jul-2015 21:30:41 UTC