[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 020004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE SEP 01 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

THE CENTER OF TROPICAL STORM FRED AT 01/2100 UTC IS NEAR 18.8N
28.1W. FRED IS MOVING TOWARD THE WEST-NORTHWEST...OR 300
DEGREES...10 KNOTS. THE MINIMUM CENTRAL PRESSURE IS 1003 MB. THE
MAXIMUM SUSTAINED WIND SPEEDS ARE 45 KNOTS WITH GUSTS TO 55
KNOTS. PUBLIC ADVISORIES ABOUT TROPICAL STORM FRED ARE BEING
ISSUED UNDER THE WMO HEADER  WTNT31 KNHC...AND UNDER THE AWIPS
HEADER MIATCPAT1. FORECAST/ADVISORIES ABOUT TROPICAL STORM FRED
ARE BEING ISSUED UNDER THE WMO HEADER WTNT21 KNHC...AND UNDER
THE AWIPS HEADER MIATCMAT1. CONVECTIVE PRECIPITATION...SCATTERED
TO NUMEROUS STRONG WITHIN A 60 NM TO 75 NM RADIUS OF THE CENTER.
UPPER LEVEL ANTICYCLONIC OUTFLOW IS SENDING MIDDLE LEVEL AND
HIGH LEVEL CLOUDS TOWARD THE NORTHEAST...AWAY FROM FRED...
COVERING THE ATLANTIC OCEAN ELSEWHERE FROM 20N TO 27N BETWEEN
AFRICA AND 32W.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 40W/41W FROM 20N
SOUTHWARD...MOVING WESTWARD 10 TO 15 KNOTS. SCATTERED TO BROKEN
LOW LEVEL AND MIDDLE LEVEL CLOUDS AND POSSIBLE RAINSHOWERS ARE
FROM 13N TO 20N BETWEEN 39W AND 45W.

A CARIBBEAN SEA TROPICAL WAVE CURVES FROM 20N65W TO 16N68W AND
TO 12N70W. THE WAVE IS MOVING WESTWARD 15 KNOTS. THIS WAVE IS
MOVING THROUGH AN AREA OF UPPER LEVEL ANTICYCLONIC WIND FLOW...
THAT IS TO THE EAST OF A CARIBBEAN SEA 18N78W MIDDLE LEVEL TO
UPPER LEVEL CYCLONIC CIRCULATION CENTER. CONVECTIVE
PRECIPITATION...SCATTERED TO NUMEROUS STRONG IN THE COASTAL
PLAINS/COASTAL WATERS OF COLOMBIA FROM 10N TO THE COAST BETWEEN
THE COLOMBIA/VENEZUELA BORDER AND 75W.

A TROPICAL WAVE IS ALONG 16N84W...THROUGH EASTERN HONDURAS AND
EASTERN NICARAGUA...TO SOUTHERN COSTA RICA NEAR 09N83W. THIS
WAVE ALSO IS MOVING THROUGH THE SAME AREA OF CYCLONIC WIND FLOW
THAT HAS BEEN GENERATED BY THE 18N78W CYCLONIC CIRCULATION
CENTER. THE MONSOON TROUGH IS ALONG 08N/09N BETWEEN 77W AND
BEYOND SOUTHERN COSTA RICA. CONVECTIVE PRECIPITATION...SCATTERED
STRONG FROM THE COAST OF PANAMA NEAR 09N TO 11N BETWEEN 79W AND
81W. WIDELY SCATTERED TO SCATTERED MODERATE AND ISOLATED STRONG
IN CENTRAL AMERICA FROM NICARAGUA TO THE YUCATAN PENINSULA
BETWEEN 85W AND 93W IN SOUTHERN MEXICO.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH IS ALONG 12N31W 09N41W 07N50W. THE ITCZ
CONTINUES FROM 07N50W INTO NORTHWESTERN FRENCH GUIANA...ACROSS
THE NORTHERN PART OF SURINAME...THROUGH CENTRAL GUYANA...ACROSS
A BIT OF BRAZIL...INTO VENEZUELA NEAR 05N62W. CONVECTIVE
PRECIPITATION...SCATTERED STRONG FROM 08N TO 10N BETWEEN 36W AND
37W. ISOLATED MODERATE IS WITHIN 60 NM TO 90 NM ON EITHER SIDE
OF THE LINE FROM 14N25W TO 10N34W TO 08N46W AND 07N59W.

...DISCUSSION...

THE GULF OF MEXICO...

UPPER LEVEL SOUTHERLY WIND FLOW SPANS THE GULF OF MEXICO FROM
92W EASTWARD. THIS WIND FLOW IS ASSOCIATED WITH BROAD UPPER
LEVEL CYCLONIC WIND FLOW...THAT IS CONNECTED WITH AN EAST TEXAS
CYCLONIC CIRCULATION CENTER THAT IS NEAR 32N96W. A TROUGH
CONTINUES FROM THE 32N96W EAST TEXAS CENTER...TO 23N94W AND TO
SOUTHERN MEXICO NEAR 19N92W. CONVECTIVE PRECIPITATION...WIDELY
SCATTERED MODERATE TO ISOLATED STRONG TO THE NORTHWEST OF THE
LINE THAT RUNS FROM 23N97W ALONG THE MEXICO GULF COAST...BEYOND
SOUTHEASTERN LOUISIANA. ISOLATED MODERATE ELSEWHERE FROM 24N
NORTHWARD...INTO PARTS OF SOUTHWESTERN FLORIDA...TO THE
SOUTHWEST OF LAKE OKEECHOBEE.

A SURFACE TROUGH IS ALONG THE LINE FROM THE FLORIDA BIG BEND
NEAR 30N84W TO A 1017 MB LOW PRESSURE CENTER THAT IS NEAR
28N85W...TO 26N87W. THIS TROUGH AND LOW PRESSURE CENTER
COMBINATION REPRESENTS THE REMNANTS OF ERIKA.

THE CARIBBEAN SEA...

A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS
NEAR 18N78W. CYCLONIC WIND FLOW THAT IS MOVING AROUND THE CENTER
COVERS THE AREA FROM 72W WESTWARD. TWO TROPICAL WAVES ARE MOVING
THROUGH THE AREA OF THE CYCLONIC WIND FLOW THAT IS MOVING AROUND
THE 18N78W CYCLONIC CENTER. PLEASE READ THE SECTION ABOUT
TROPICAL WAVES FOR MORE DETAILS.

THE SOUTHERN END OF A MIDDLE LEVEL TO UPPER LEVEL TROUGH
CONTINUES FROM A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC
CIRCULATION CENTER THAT IS NEAR 20N63W....INTO THE SOUTHEASTERN
CORNER OF THE CARIBBEAN SEA TOWARD TRINIDAD AND NORTHEASTERN
VENEZUELA. TWO TROPICAL WAVES ARE MOVING THROUGH

THE 24-HOUR RAINFALL TOTALS IN INCHES FOR THE PERIOD ENDING AT
01/1200 UTC...ACCORDING TO THE PAN AMERICAN TEMPERATURE AND
PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...ARE 1.06 IN
BERMUDA...0.66 IN GUADELOUPE...0.53 IN MERIDA MEXICO...AND 0.10
IN ST. THOMAS.

...HISPANIOLA...

A CARIBBEAN SEA TROPICAL WAVE CURVES FROM 20N65W TO 16N68W AND
TO 12N70W. THE WAVE IS MOVING WESTWARD 15 KNOTS. THIS WAVE IS
MOVING THROUGH AN AREA OF UPPER LEVEL ANTICYCLONIC WIND FLOW...
THAT IS TO THE EAST OF A CARIBBEAN SEA 18N78W MIDDLE LEVEL TO
UPPER LEVEL CYCLONIC CIRCULATION CENTER. THE TROPICAL WAVE
SHOULD BE REACHING HISPANIOLA DURING THE NEXT 24 HOURS OR LESS.



THE GFS MODEL FORECAST FOR 250 MB SHOWS THAT CYCLONIC WIND FLOW
WILL CROSS HAITI AT THE START OF THE 48-HOUR FORECAST PERIOD...
AND ANTICYCLONIC WIND FLOW WILL BE MOVING ACROSS THE DOMINICAN
REPUBLIC. THE CYCLONIC CIRCULATION CENTER THAT IS RESPONSIBLE
FOR THE CYCLONIC WIND FLOW IN HAITI EVENTUALLY WILL MOVE TOWARD
SOUTHERN JAMAICA...AND ANTICYCLONIC WIND FLOW WILL COVER THE
ENTIRE AREA FOR AT LEAST THE FIRST 24 HOURS. A NORTHEAST-TO-
SOUTHWEST ORIENTED TROUGH WILL MOVE INTO THE AREA AFTER 24
HOURS...AND IT WILL CONTINUE UNTIL THE END OF THE PERIOD. THE
GFS MODEL FORECAST FOR 500 MB AND FOR 700 MB SHOWS THAT AN
ANTICYCLONIC CIRCULATION CENTER WILL BE IN THE ATLANTIC OCEAN
NEAR 29N67W. LARGE-SCALE EAST-TO-NORTHEAST WIND FLOW WILL MOVE
ACROSS THE AREA. AN INVERTED TROUGH WILL MOVE ACROSS THE AREA
SLOWLY...CAUSING SOME SLIGHT WIND SHIFTS.

THE ATLANTIC OCEAN...

A MIDDLE LEVEL TO UPPER LEVEL INVERTED TROUGH EXTENDS FROM THE
NORTHERN BAHAMAS TO SOUTHEASTERN CUBA. THE TROUGH EVENTUALLY
CONTINUES SOUTHWARD TO PANAMA IN THE SOUTHWESTERN CORNER OF THE
CARIBBEAN SEA. COMPARATIVELY DRIER AIR IN SUBSIDENCE SURROUNDS
THE INVERTED TROUGH AT THIS MOMENT.

A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH 32N38W TO
28N42W 24N45W 22N50W...CONTINUING TO 21N56W...AND TO A MIDDLE
LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER THAT IS NEAR
20N63W. THE TROUGH CONTINUES INTO THE SOUTHEASTERN CORNER OF THE
CARIBBEAN SEA TOWARD TRINIDAD AND NORTHEASTERN VENEZUELA. A
SURFACE TROUGH IS IN THE ATLANTIC OCEAN ALONG 32N38W 29N40W
25N43W. CONVECTIVE PRECIPITATION...IN THE ATLANTIC OCEAN...
ISOLATED MODERATE TO LOCALLY STRONG FROM 17N NEAR PUERTO RICO TO
23N IN THE ATLANTIC OCEAN BETWEEN 56W AND 66W. ISOLATED MODERATE
WITHIN 150 NM ON EITHER SIDE OF THE LINE THAT PASSES THROUGH
32N33W TO 25N40W...AND WITHIN 250 NM ON EITHER SIDE OF THE
LINE FROM 25N40W TO 22N53W.

ONE SURFACE TROUGH IS ALONG 32N50W 30N50W 28N51W. A SECOND
SURFACE TROUGH PASSES THROUGH 32N56W 29N59W 28N63W. UPPER LEVEL
ANTICYCLONIC WIND FLOW IS ON TOP OF THE AREAS OF THE TWO SURFACE
TROUGHS...TO THE NORTH AND NORTHWEST OF THE LINE THAT PASSES
THROUGH 32N44W 27N49W 25N61W 26N75W 26N80W. CONVECTIVE
PRECIPITATION...ISOLATED MODERATE IN THE AREA OF ANTICYCLONIC
WIND FLOW TO THE NORTHWEST OF THE 32N44W 26N80W LINE. A SURFACE
RIDGE EXTENDS FROM A 1021 MB HIGH PRESSURE CENTER THAT IS NEAR
30N68W...TO 23N57W AND 21N44W. A SECOND SURFACE RIDGE PASSES
THROUGH 32N23W TO 28N31W AND 22N38W.

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

$$
MT
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