Tropical Weather Discussion
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000
AXPZ20 KNHC 301547
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE SEP 30 2014

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...
RACHEL WAS DOWNGRADED TO A TROPICAL DEPRESSION AT 30/1500 UTC.
AT THIS TIME...IT IS CENTERED NEAR 23.1N 117.5W. THE DEPRESSION
IS NEARLY STATIONARY...AND A VERY SLOW WEST-SOUTHWESTWARD MOTION
IS EXPECTED OVER THE NEXT COUPLE OF DAYS. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1005 MB. MAXIMUM SUSTAINED WINDS HAVE
DECREASED TO 30 KT GUSTS 40 KT. CONTINUED WEAKENING IS FORECAST
DURING THE NEXT 48 HOURS...AND RACHEL IS LIKELY TO BECOME A
REMNANT LOW LATER TODAY. RACHEL HAS LOST ALL ITS DEEP
CONVECTION. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMEP3/WTPZ23 FOR MORE DETAILS.

A 1008 MB LOW PRES LOCATED NEAR 15N100W REMAINS POORLY ORGANIZED
ALONG THE MONSOON TROUGH ROUGHLY 125 NM S OF ACAPULCO MEXICO.
THIS IS IN THE AREA WHERE VORTICITY HAS BEEN ENHANCED BY A PAIR
OF TROPICAL WAVE PASSAGES. SCATTERED MODERATE ISOLATED STRONG
CONVECTION IS NOTED MAINLY WITHIN 90NM SE AND NW QUADRANTS OF
LOW CENTER. GLOBAL MODELS CONTINUE TO INDICATE THAT THIS BROAD
LOW PRES AREA WILL SLOWLY BECOME BETTER ORGANIZED OVER THE NEXT
SEVERAL DAYS AS IT DRIFTS TO THE WNW PARALLELING THE COAST OF
MEXICO. THE LOW PRES HAS A MEDIUM CHANCE OF DEVELOPING INTO A
TROPICAL CYCLONE WITHIN THE NEXT 48 HOURS AND A HIGH CHANCE OF
DEVELOPING INTO A TROPICAL CYCLONE OVER THE NEXT 3 TO 5 DAYS.
REGARDLESS OF TROPICAL CYCLONE FORMATION...THIS DISTURBANCE WILL
LIKELY PRODUCE LOCALLY HEAVY RAIN OVER PORTIONS OF SOUTHERN
MEXICO THAT COULD CAUSE FLASH FLOODING AND MUD SLIDES.

...TROPICAL WAVES...
A TROPICAL WAVE MOVING ACROSS THE YUCATAN PENINSULA AND
GUATEMALA EXTENDS INTO THE EPAC TO NEAR 11N90W. SCATTERED
MODERATE CONVECTION IS OBSERVED ON SATELLITE IMAGERY WHERE THE
WAVE AXIS MEETS THE MONSOON TROUGH. THE WAVE WILL CONTINUE TO
MOVE WESTWARD REACHING THE GULF OF TEHUANTEPEC ON WED.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM 10N85W TO 1008 MB LOW PRES LOCATED
NEAR 15N100W TO 12N114W. ITCZ CONTINUES FROM 12N114W TO 12N125W
TO 11N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS
NOTED FROM 10N TO 13N BETWEEN 88W AND 92W. SCATTERED MODERATE
CONVECTION IS FROM 09N TO 13N BETWEEN 110W AND 114W.

...DISCUSSION...
MARINE GUIDANCE SUGGESTS INCREASING SW WIND FLOW S OF THE
MONSOON TROUGH AXIS BETWEEN 100W AND 115W LATE TONIGHT THROUGH
THU IN ASSOCIATION WITH TROPICAL LOW PRES FORECAST TO DEVELOP
LATER THIS WEEK. SEE SPECIAL FEATURES FOR DETAILS. EXPECT SW
WINDS OF 20-25 KT AND BUILDING SEAS OF 8-10 FT FROM 09N TO 12N
BETWEEN 98W AND 111W BY WED MORNING...AND FROM 09N TO 14N
BETWEEN 100W AND 110W...AND ALSO FROM 08N TO 11N BETWEEN 110W
AND 114W BY THU MORNING.

SEAS TO 12 FT ARE STILL NOTED WITHIN 40 NM NW QUADRANT OF RACHEL
LIKELY DUE TO THE PRES GRADIENT BETWEEN THE TROPICAL CYCLONE AND
A RIDGE DOMINATING THE N WATERS MAINLY N OF 15N W OF 122W.

CLUSTERS OF MODERATE TO STRONG CONVECTION HAVE DEVELOPED NEAR
THE SOUTHERN END OF A TROUGH EXTENDING OVER WESTERN MEXICO. THIS
CONVECTION COVERS THE AREA FROM 18N TO 22N E OF 107W TO THE
MEXICAN COAST.

LONG PERIOD CROSS EQUATORIAL SW SWELL WILL CONTINUE TO SPREAD
ACROSS THE SOUTH CENTRAL WATERS DURING THE NEXT FEW DAYS. THIS
SWELL EVENT WILL COMBINE WITH SW WIND WAVES GENERATED SOUTH OF
THE MONSOON TROUGH PREVIOUSLY MENTIONED...RAISING SEAS TO 9 FT S
OF A LINE S OF A LINE FROM 03.4N90W TO 12N100W TO 12N120W TO
00N135W BY WED MORNING.

$$
GR



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