Tropical Weather Discussion
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000
AXNT20 KNHC 311756
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON AUG 31 2015

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...
HURRICANE FRED IS CENTERED NEAR 16.9N 24.2W AT 31/1800 UTC OR
ABOUT 20 NM NNE OF RIBEIRA BRAVA IN THE CAPE VERDE ISLANDS AND
ABOUT 50 NM ESE OF RIBEIRA GRANDE IN THE CAPE VERDE ISLANDS
MOVING NW AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 986
MB. MAXIMUM SUSTAINED WIND SPEED IS 75 KT WITH GUSTS TO 90 KT.
SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 14N-
18N BETWEEN 22W-25W. SCATTERED MODERATE IS ELSEWHERE FROM 17N-
21N BETWEEN 15W-20W...AND FROM 09N-14N BETWEEN 22W-28W. SEE
LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT1/WTNT31 KNHC AND THE FULL FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 10N60W TO 19N57W MOVING W AT 15-20
KT. THE WAVE COINCIDES WITH RELATIVELY BROAD 700 MB TROUGHING
BETWEEN 55W-63W...WITH A MAXIMUM IN 850 MB RELATIVE VORTICITY
ALONG THE WAVE AXIS FROM 12N-17N. ISOLATED MODERATE CONVECTION
IS FROM 18N-21N BETWEEN 54W-59W.

TROPICAL WAVE EXTENDS FROM 10N75W TO 19N75W MOVING W AT 25 KT.
THE WAVE LIES WITHIN THE SOUTHWESTERN PERIPHERY OF THE LOW TO
MID-LEVEL SUBTROPICAL RIDGE ANCHORED OVER THE SW NORTH ATLC NEAR
30N69W. ISOLATED MODERATE CONVECTION IS FROM 16N-19N BETWEEN 75W-
78W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM 12N28W TO A 1013 MB LOW
NEAR 07N38W TO 08N45W. OUTSIDE OF CONVECTION ASSOCIATED WITH
HURRICANE FRED...ISOLATED MODERATE CONVECTION IS FROM 05N-08N
BETWEEN 40W-43W.

...DISCUSSION...

GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL TROUGH AXIS EXTENDS FROM OVER THE OHIO
RIVER VALLEY SW TO OVER THE ARKLATEX REGION TO A BROAD BASE OVER
THE RIO GRANDE RIVER VALLEY NEAR 26N100W. THE TROUGHING IS
PROVIDING MUCH OF THE GULF WITH SOUTHWESTERLY FLOW ALOFT THIS
AFTERNOON. NEAREST TO THE MID-LEVEL 500 MB RELATIVE VORTICITY
MAXIMUM OVER SOUTHERN TEXAS AND NE MEXICO...MIDDLE TO UPPER
LEVEL DIFFLUENCE IS GENERATING SCATTERED SHOWERS AND TSTMS
ACROSS THE WESTERN GULF N OF 22N W OF 93W. FARTHER EAST...A
MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS NOTED ON WATER VAPOR
IMAGERY MOVING OVER THE EAST-CENTRAL GULF WATERS NEAR 27N83W.
THE SHORTWAVE SUPPORTS A WEAK 1014 MB LOW CENTERED NEAR 25N85W
WITH SURFACE TROUGHING EXTENDING N-NE TO THE FLORIDA BIG BEND
REGION NEAR 30N83W...AND SW FROM THE LOW TO NEAR THE NW CORNER
OF THE YUCATAN PENINSULA NEAR 21N90W. GIVEN THE FAVORABLE UPPER
LEVEL ENVIRONMENT ALOFT AND MAXIMUM LOW-LEVEL MOISTURE
CONVERGENCE ALONG AND EAST OF THE SURFACE TROUGHING...SCATTERED
SHOWERS AND ISOLATED TSTMS ARE OCCURRING FROM 24N-27N BETWEEN
82W-84W...AND S OF 23N BETWEEN 83W-87W...INCLUDING THE
APPROACHES TO THE YUCATAN CHANNEL. OTHERWISE...GENERALLY GENTLE
TO MODERATE ANTICYCLONIC FLOW PERSISTS AS SURFACE HIGH PRESSURE
REMAINS ANCHORED ACROSS A LARGE PORTION OF THE MID-ATLC AND SE
CONUS THROUGH THURSDAY.

CARIBBEAN SEA...
UPPER LEVEL RIDGING EXTENDS OVER THE YUCATAN CHANNEL REGION AND
MUCH OF THE NW CARIBBEAN THIS AFTERNOON. GIVEN THE FAVORABLE
UPPER LEVEL DIFFLUENT ENVIRONMENT...SCATTERED SHOWERS AND TSTMS
ARE OCCURRING N OF 19N BETWEEN 82W-88W...INCLUDING FAR WESTERN
CUBA...AND THE FAR EASTERN YUCATAN PENINSULA. OTHERWISE...THE
OTHER MAIN UPPER LEVEL FEATURE IMPACTING THE BASIN IS A BROAD
UPPER LEVEL LOW CENTERED OVER THE WINDWARD PASSAGE REGION NEAR
18N75W. THE UPPER LEVEL LOW ALONG WITH A WEAK TROPICAL WAVE
ALONG 76W IS GENERATING A FEW ISOLATED SHOWERS AND TSTMS IN THE
VICINITY OF JAMAICA AND ACROSS AN AREA SOUTH OF HISPANIOLA IN
THE VICINITY OF 16N72W. FINALLY...THE APPROACH OF ANOTHER
TROPICAL WAVE...CURRENTLY ALONG 59W...IS EXPECTED TO INCREASE
PRECIPITATION PROBABILITIES FOR THE LESSER ANTILLES THIS
AFTERNOON THROUGH EARLY TUESDAY. ISOLATED SHOWERS AND POSSIBLE
ISOLATED TSTMS ALONG WITH POSSIBLE GUSTY WINDS WILL ACCOMPANY
THE WAVE AS IT ENTERS THE EASTERN CARIBBEAN BY TUESDAY AFTERNOON.

...HISPANIOLA...
CURRENTLY...MOSTLY CLEAR SKIES ARE NOTED ON VISIBLE SATELLITE
IMAGERY DUE LARGELY TO RELATIVELY DRY CONDITIONS ALOFT AND
OVERALL STABILITY PROVIDED BY THE SUBTROPICAL RIDGE ANCHORED
ACROSS THE SW NORTH ATLC REGION. LITTLE CHANGE IN SYNOPTIC
CONDITIONS ARE EXPECTED THROUGH TUESDAY AFTERNOON WHEN A
TROPICAL WAVE CURRENTLY ALONG 59W WILL APPROACH AND INCREASE
PROBABILITY OF PRECIPITATION ACROSS THE ISLAND.

ATLANTIC OCEAN...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS ANCHORED OVER THE SW
NORTH ATLC NEAR 29N71W WITH A RIDGE AXIS EXTENDING W TO 29N77W
THEN SW OVER THE SOUTHERN FLORIDA PENINSULA. LOW-LEVEL MOISTURE
CONVERGENCE ALONG WITH MIDDLE TO UPPER LEVEL DIFFLUENCE ON THE
PERIPHERY OF THE RIDGING IS GENERATING SCATTERED SHOWERS AND
TSTMS N OF 30N BETWEEN 78W-80W. OTHERWISE...THE MAIN FEATURE
INFLUENCING THE SW NORTH ATLC IS A SURFACE RIDGE ANCHORED BY A
1022 MB HIGH CENTERED NEAR 31N69W. FARTHER EAST...THE CENTRAL
ATLC IS GENERALLY UNDER THE INFLUENCE OF A WEAKER SURFACE RIDGE
ANCHORED BY A 1020 MB HIGH CENTERED NEAR 23N45W...HOWEVER TO THE
NW A WEAK 1018 MB LOW IS CENTERED NEAR 33N56W WITH A SURFACE
TROUGH EXTENDING SW TO 29N61W. SCATTERED SHOWERS AND TSTMS ARE
OCCURRING FROM 30N-33N BETWEEN 52W-56W. FINALLY...AS MENTIONED
ABOVE...THE MAIN FOCUS FOR THE EASTERN ATLC IS HURRICANE FRED AS
IT TRACKS ACROSS THE CAPE VERDE ISLANDS THIS AFTERNOON.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
HUFFMAN


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