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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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