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AXPZ20 KNHC 301604
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU JUL 30 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 FEATURES...

THE CENTER OF TROPICAL STORM GUILLERMO AT 30/1500 UTC WAS NEAR 9.1N 127.5W 1002 MB...MOVING WNW OR 290 DEG AT 11 KT. MAXIMUM SUSTAINED WINDS 40 KT GUSTS 50 KT. TROPICAL STORM FORCE WINDS WITHIN 50 NM OF CENTER EXCEPT 0 NM SW QUADRANT. SEAS 12 FT OR GREATER WITHIN 0 NM OF CENTER EXCEPT 150 NM NE QUADRANT WITH SEAS TO 13 FT. ELSEWHERE WITHIN 300 NM NE SEMICIRCLE WINDS 20 TO 33 KT. SEAS 8 TO 11 FT. CONVECTIVE PRECIPITATION...NUMEROUS STRONG SURROUNDS THE CENTER FROM 07N TO 10N BETWEEN 126W AND 129W. SCATTERED STRONG WITHIN 180 TO 300 NM TO THE NORTH OF THE CENTER IN A BAND. SCATTERED MODERATE ISOLATED STRONG IS WITHIN 240 NM E SEMICIRCLE...AND WITHIN 350 TO 650 NM NE QUADRANT... EVERYTING IN THE SAME EAST-TO-WEST ORIENTED BAND. GUILLERMO IS EXPECTED TO CONTINUE ON THIS WEST-NORTHWESTWARD TRAJECTORY DURING THE NEXT TWO TO THREE DAYS. WARM SEA SURFACE TEMPERATURES AND FAVORABLE ATMOSPHERIC CONDITIONS SHOULD ALLOW THE SYSTEM TO STRENGTHEN GRADUALLY TO A HURRICANE IN 24 HOURS OR SO. GUILLERMO EVENTUALLY IS FORECAST TO REMAIN AT HURRICANE STRENGTH AS LATE AS MONDAY OF THE NEXT WEEK. PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS.

THE CENTER OF POST-TROPICAL CYCLONE EIGHT-E AT 30/1500 UTC WAS NEAR 16.5N 139.4W 1007 MB...MOVING W OR 270 DEG AT 11 KT. MAXIMUM SUSTAINED WINDS 25 KT GUSTS 35 KT. WITHIN 420 NM NE SEMICIRCLE WINDS 20 TO 25 KT. SEAS TO 11 FT. THE LOW LEVEL CIRCULATION CONTINUES TO WEAKEN SLOWLY...WITH THE SURFACE PRESSURE GRADIENT TO THE NORTH INDUCED BY THE NE PACIFIC RIDGE MAINTAINING A BROAD ZONE OF 20-25 KT WINDS ACROSS THE N SEMICIRCLE. CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO STRONG WITHIN 80 TO 100 NM NE QUADRANT...AND LIMITED ELSEWHERE. THIS SYSTEM WILL CONTINUE TO MOVE WEST-SOUTHWESTWARD DURING THE NEXT FEW DAYS AND WEAKEN GRADUALLY INTO AN OPEN TROUGH WITHIN 24 TO 36 HOURS AS IT MOVES TO THE WEST OF THE DISCUSSION AREA. PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMEP3/WTPZ23 KNHC FOR MORE DETAILS.


...TROPICAL WAVES...

TROPICAL WAVE ALONG 90W S OF 20N MOVING WEST 10 TO 15 KT. THE CONVECTIVE PRECIPITATION IS DESCRIBED IN THE PARAGRAPH THAT IS ABOUT THE MONSOON TROUGH.

TROPICAL WAVE ALONG 103W S OF 14N MOVING WEST 15 KNOTS. THE CONVECTIVE PRECIPITATION IS DESCRIBED IN THE PARAGRAPH THAT IS ABOUT THE MONSOON TROUGH.

THE TROPICAL WAVE THAT WAS ALNOG 120W/121W SIX HOURS AGO HAS BEEN ABSORBED INTO THE BROADER CIRCULATION OF TROPICAL STORM GUILLERMO.


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

MONSOON TROUGH FROM 08N86W TO 08N94W TO 06N109W TO 07N117W. SCATTERED TO NUMEROUS STRONG FROM 03N TO 08N E OF 80W. SCATTERED STRONG FROM 05N TO 07N BETWEEN 93W AND 96W...AND FROM 13N TO 15N BETWEEN 94W AND 96W. SCATTERED MODERATE ISOLATED STRONG FROM 08N TO 15N BETWEEN 96W AND 102W.


...DISCUSSION...

A WEAKENED SURFACE RIDGE CENTERED ACROSS THE NE PACIFIC EXTENDS SE INTO THE AREA AND PASSES THROUGH 30N134W TO 21N113W. THE SLACKENED PRESSURE GRADIENT BETWEEN THE RIDGE AND THE TYPICAL TROUGH THAT IS SEEN ALONG BAJA CALIFORNIA HAS ALLOWED NW WINDS TO SUBSIDE DURING THE PAST 12-24 HOURS 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 RIDGE WILL BEGIN TO SLOWLY STRENGTHEN ACROSS THIS REGION BEGINNING TONIGHT...WITH THE NWLY FLOW SLOWLY INCREASING OFFSHORE OF THE BAJA PENINSULA...POSSIBLY REACHING 20 KT WITH POCKETS TO 25 KT LATE FRI AFTERNOON AND EVENING...WITH SEAS BUILDING 6-8 FT THERE.

AS MENTIONED ABOVE...THE SURFACE PRESSURE GRADIENT THAT EXISTS BETWEEN THE SUBTROPICAL RIDGE AND LOWER SURFACE PRESSURES ASSOCIATED WITH TROPICAL DEPRESSION EIGHT-E IS RESULTING A BROAD SWATH OF 20 TO 25 KT TRADE WINDS IN THE WESTERN PART OF THE AREA FROM 17N TO 22N AND TO THE WEST OF 132W. THE WINDS WILL GRADUALLY MOVE W OF THE AREA LATE TODAY...BEFORE FRESHENING AGAIN S OF 20N ON FRI AS GUILLERMO CONTINUES WNW AND TRACK W OF 130W.

GAP WINDS... THE GULF OF PAPAGAYO...STRONG TRADE WINDS ACROSS 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 HAVE INCREASED AGAIN OVERNIGHT TO 20-25 KT ACROSS THE NICARAGUAN COASTAL WATERS IN THE LEE OF LAKES NICARAGUA AND MANAGUA...WILL DIMINISH BY LATE AFTERNOON...AND THEN INCREASE AGAIN TO AROUND 20 KT WITH ISOLATED AREAS TO 25 KT FRIDAY NIGHT. SEAS DOWNWIND OF THIS REGION WILL FLUCTUATE AT 6 TO 8 FT OVER THE NEXT 36 HOURS.

A NARROW PLUME OF NORTHERLY WINDS IN THE RANGE OF 20 TO 25 KNOTS WAS DEPICTED BY OVERNIGHT SCATTEROMETER DATA...AND EXTENDED SOUTH SOUTHWEST TO NEAR 15N95W...WHERE SEAS BUILT TO 7-8 FT. THESE WINDS WILL ALSO DIMINISH SLIGHTLY BY AFTERNOON AND THEN PULSE AGAIN TO 20 TO 25 KNOTS TONIGHT INTO THE MORNING HOURS ON FRI.

$$ MT

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