Tropical Weather Discussion
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000
AXPZ20 KNHC 210949
TWDEP

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN SEP 21 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0945 UTC.

...SPECIAL FEATURES...

TROPICAL STORM POLO LOCATED NEAR 21.6N 110.5W OR ABOUT 100 MILES
S-SW OF THE SOUTHERN TIP OF BAJA CALIFORNIA PENINSULA AT AT 0900
UTC SEP 21. THE MINIMUM CENTRAL PRESSURE IS ESTIMATED AT 1004
MB. POLO IS MOVING W OR 285 DEG AT 06 KT...AND IS EXPECTED TO
CONTINUE ON THIS TRACK THROUGH MON. MAXIMUM SUSTAINED WINDS ARE
CURRENTLY ARE AT 35 KT WITH GUSTS TO 45 KT.

STRONG NE WIND SHEAR IS EXPOSING THE CENTER WELL TO THE SE OF A
CLUSTER OF SCATTERED MODERATE ISOLATED STRONG WITHIN 60 NM OF
21.5N111.5W. SCATTERED MODERATE CONVECTION IS ALSO NOTED WITHIN
45 NM OF 23N113W. POLO MAY STILL PRODUCE RAINFALL AMOUNTS OF 1
TO 2 INCHES ACROSS THE SOUTHERN BAJA CALIFORNIA PENINSULA TODAY.

SWELLS GENERATED BY POLO WILL AFFECT PORTIONS OF THE SOUTHERN
BAJA CALIFORNIA PENINSULA OVER THE NEXT FEW DAYS. THESE SWELLS
CAN CONTRIBUTE TO THE GENERATION OF LIFE THREATENING SURF AND
RIP CURRENT CONDITIONS. SEE THE LATEST PUBLIC ADVISORY UNDER
AWIPS/WMO HEADERS MIATCPEP2/WTPZ32 KNHC AND FORECAST ADVISORY
UNDER HEADERS MIATCMEP2/WTPZ22 KNHC FOR ADDITIONAL DETAILS.

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

THE MONSOON TROUGH EXTENDS W ACROSS PANAMA AND COSTA RICA
BETWEEN 09-10N TO THE PACIFIC COAST OF COSTA RICA AT 10N85W...
CONTINUES NW TO 11N98W THEN SW TO 07N113W WHERE IT LOSES
IDENTITY. SCATTEROMETER WINDS INDICATE THE MONSOON TROUGH
RESUMES NEAR 15N120W AND CONTINUES SW TO BEYOND 12N140W.
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED WITHIN
150 NM EITHER SIDE OF A LINE FROM 06N77W TO 10N95W TO 07N111W.

SCATTERED MODERATE ISOLATED STRONG CONVECTION IS ALSO OBSERVED
OVER AND WITHIN 180 NM W OF THE COAST OF CENTRAL AMERICA AND
MEXICO FROM 86-102W.

LOW PRESSURE IS EXPECTED TO GRADUALLY DEVELOP ALONG THE MONSOON
TROUGH NEAR 12N95W OVER THE NEXT COUPLE OF DAYS WITH A 1007 MB
SURFACE LOW...POSSIBLY TROPICAL CYCLONE...EXPECTED ON TUE
EVENING. THIS LOW SHOULD TRACK W ALONG THE MONSOON TROUGH WITH
SW FLOW INCREASING TO 20-25 KT OVER THE SE SEMICIRCLE LATE THU.

...DISCUSSION...
A 1017 MB HIGH PRESSURE IS QUASI-STATIONARY NEAR 27N137W WITH
ITS ANTICYCLONIC ENVELOPE DOMINATING THE MARINE AREA W OF 120W
AND TO THE N OF THE MONSOON TROUGH WITH GENERALLY NE-E 10-15 KT
TRADES ACROSS THE TROPICS W OF 120W. A WEAK COLD FRONT WILL MOVE
INTO THE FAR NW WATERS LATE TONIGHT. THE FRONT WILL INITIALLY BE
ACCOMPANIED BY ONLY A SW-W-WNW 10 KT WIND SHIFT. THE WEAK FRONT
WILL REACH FROM 32N134W TO 26N137W LATE TUE. A SECONDARY
NORTHWESTERLY 15 KT SURGE WILL PUSH THE FRONT E TO A POSITION
FROM 32N128W TO 25N140W LATE WED WITH NW WINDS INCREASING TO 15
KT W OF THE FRONT. ADDITIONALLY...NW SWELLS W OF THE FRONT WILL
MIX WITH LONG PERIOD SE SWELL...RESULTING IN SEAS BUILDING 8-12
FT ACROSS THE WATERS NW OF THE FRONT...WITH THE MAXIMUM SEAS
ALONG 31N. THE FRONT WILL REACH FROM 32N117W TO 22N140W LATE THU
WHERE IT WILL LOSE IDENTITY...BUT NW WINDS WILL INCREASE TO 15-
20 KT ALONG THE PACIFIC COAST OF THE BAJA PENINSULA TO THE N OF
26N...WITH SEAS BUILDING 6-9 FT IN MIXING NW AND SE SWELL
WITHIN THIS AREA ON FRI.

$$
NELSON



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