[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 031756
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT OCT 03 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 JOAQUIN IS CENTERED NEAR 26.4N 70.9W AT 03/1800 UTC OR
ABOUT 475 NM SW OF BERMUDA MOVING NE AT 16 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 933 MB. MAXIMUM SUSTAINED WIND SPEED IS 135
KT WITH GUSTS TO 165 KT. NUMEROUS MODERATE CONVECTION IS WITHIN
180 NM OF CENTER WITH SCATTERED MODERATE CONVECTION ELSEWHERE
FROM 20N-29N BETWEEN 62W-74W. SEE LATEST 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.

A 1006 MB LOW IS CENTERED NEAR 27N53W AND CURRENTLY SUPPORTED
ALOFT BY UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL LOW
CENTERED TO THE SOUTH NEAR 23N52W AND AN UPPER LEVEL RIDGE
ANCHORED TO THE NORTH NEAR 35N52W. THE LOW HAS REMAINED BETWEEN
THE CIRCULATION OF JOAQUIN TO THE WEST AND AT THE WESTERN EXTENT
OF A FRONTAL BOUNDARY TO THE EAST. THE SYSTEM IS GENERATING
STRONG TO NEAR GALE FORCE WINDS IN THE NORTHERN SEMICIRCLE DUE
LARGELY IN PART TO THE STRONGER REGIONAL PRESSURE GRADIENT.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 07N23W TO 17N26W MOVING W AT 10 KT.
THE WAVE REMAINS EMBEDDED WITHIN THE SOUTHWESTERN PERIPHERY OF A
700 MB RIDGE ANCHORED OVER COASTAL WEST AFRICA NEAR 22N15W. THIS
WAVE IS FORECAST TO MERGE WITH THE TROPICAL WAVE DESCRIBED BELOW
WHICH IS ALONG 34W BY LATE SUNDAY. ISOLATED MODERATE CONVECTION
IS FROM 14N-16N BETWEEN 25W-32W.

TROPICAL WAVE EXTENDS FROM 09N33W TO 18N35W MOVING W AT 5-10 KT.
THE WAVE COINCIDES WITH 700 MB TROUGHING BETWEEN 30W-40W AND A
MAXIMUM IN 850 MB RELATIVE VORTICITY FOCUSED AROUND A 1009 MB
LOW CENTERED AT THE SOUTHERN EXTENT OF THE WAVE AXIS NEAR
09N33W. SCATTERED MODERATE CONVECTION IS FROM 05N-11N BETWEEN
26W-37W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 17N16W TO
18N22W...THEN RESUMES NEAR A 1009 MB LOW CENTERED NEAR 09N33W TO
12N41W TO 10N46W. ASIDE FROM CONVECTION OCCURRING IN ASSOCIATION
WITH THE TROPICAL WAVES...SCATTERED MODERATE CONVECTION IS FROM
08N-13N BETWEEN 43W-52W.

...DISCUSSION...

GULF OF MEXICO...
A VIGOROUS MIDDLE TO UPPER LEVEL LOW IS NOTED ON WATER VAPOR
IMAGERY CENTERED OVER THE SE CONUS WITH A TROUGH AXIS EXTENDING
SOUTHWARD OVER THE EASTERN GULF FROM OVER THE FLORIDA PANHANDLE
TO OVER THE TAMPA BAY REGION THEN SOUTHWARD TO A BASE OVER THE
NW CARIBBEAN SEA. WITH THE GULF MOSTLY ON THE WESTERN PERIPHERY
OF THE TROUGH AXIS...VERY DRY AIR ALOFT AND STRONG SUBSIDENCE
PREVAILS. AS A RESULT...SURFACE RIDGING LIES TO THE WEST WITH
AXIS EXTENDING ALONG 98W AND GENERALLY N-NW GENTLE TO MODERATE
BREEZE CONDITIONS OCCURRING ACROSS THE BASIN THIS AFTERNOON.
LITTLE CHANGE IS EXPECTED THROUGH SUNDAY INTO MONDAY.

CARIBBEAN SEA...
DUE TO THE PRESENCE OF HURRICANE JOAQUIN ACROSS THE CENTRAL
BAHAMAS...NORMAL TRADE WIND FLOW HAS BEEN DISRUPTED WITH GENTLE
TO MODERATE SOUTHERLY WINDS GENERALLY E OF 71W AND GENTLE TO
MODERATE WEST-SOUTHWEST WINDS W OF 71W. RECENT SCATTEROMETER
PASSES CONFIRM THIS FLOW WITH A WEAK SURFACE TROUGH ANALYZED
FROM CENTRAL CUBA NEAR 22N78W TO THE GULF OF HONDURAS NEAR
16N87W. THE BOUNDARY IS PRODUCING ISOLATED SHOWERS AND TSTMS
WITHIN 150 NM SE OF THE TROUGH AXIS AND ACROSS PORTIONS OF THE
WINDWARD PASSAGE REGION. FARTHER EAST...AN UPPER LEVEL SHORTWAVE
TROUGH AND MID-LEVEL ENERGY IS NOTED ON WATER VAPOR IMAGERY IN
THE VICINITY OF 22N64W AND IS LIKELY ENHANCING OUTER CONVECTIVE
BANDS ASSOCIATED WITH JOAQUIN. SCATTERED SHOWERS AND TSTMS ARE
OCCURRING FROM 17N-21N BETWEEN 60W-65W. OTHERWISE...TRADE WIND
FLOW IS EXPECTED TO RE-ESTABLISH ITSELF ACROSS THE EASTERN TWO-
THIRDS OF THE BASIN BY LATE SUNDAY INTO MONDAY.

...HISPANIOLA...
CURRENTLY...THE OUTER CONVECTIVE PRECIPITATION BANDS OF
HURRICANE JOAQUIN REMAIN ALONG THE NORTHERN SHORE OF HISPANIOLA
WITH ISOLATED SHOWERS OCCURRING ELSEWHERE. THE CONVECTION IS
EXPECTED TO PERSIST DURING THE NEXT 24 HOURS AND THEN GRADUALLY
DIMINISH THEREAFTER AS THE HURRICANE TRACKS NW AWAY FROM THE
ISLAND.

ATLANTIC OCEAN...
THE MAIN FEATURE ACROSS THE SW NORTH ATLC IS HURRICANE JOAQUIN.
WHILE JOAQUIN REMAINS THE FOCUS...THE AREA OF LOWER PRESSURE
VALUES EXTENDS NORTHWESTWARD ALONG A STATIONARY FRONT INTO A 998
MB LOW CENTERED OFF THE COAST OF SOUTH CAROLINA NEAR 32N79W.
SCATTERED SHOWERS AND TSTMS ARE OCCURRING N OF 29N BETWEEN 77W-
81W. THE LOW IS SUPPORTED BY A VIGOROUS MIDDLE TO UPPER LEVEL
LOW CENTERED OVER THE SE CONUS. OTHERWISE...HURRICANE JOAQUIN IS
EXPECTED TO TRACK GENERALLY NORTHEASTWARD THROUGH SUNDAY AND
NORTH OF THE DISCUSSION AREA THEREAFTER. FARTHER EAST...A 1006
MB LOW IS CENTERED NEAR 27N53W AND CURRENTLY SUPPORTED ALOFT BY
UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL LOW CENTERED TO
THE SOUTH NEAR 23N52W AND AN UPPER LEVEL RIDGE ANCHORED TO THE
NORTH NEAR 35N52W. THE LOW HAS REMAINED BETWEEN THE CIRCULATION
OF JOAQUIN TO THE WEST AND AT THE WESTERN EXTENT OF A FRONTAL
BOUNDARY TO THE EAST GENERATING STRONG TO NEAR GALE FORCE WINDS
IN THE NORTHERN SEMICIRCLE DUE LARGELY IN PART TO THE STRONGER
REGIONAL PRESSURE GRADIENT IN PLACE. OTHERWISE...THE EASTERN
ATLC IS UNDER THE INFLUENCE OF A COLD FRONT EXTENDING FROM
32N23W TO 24N34W TO 25N43W. ISOLATED SHOWERS AND TSTMS ARE
OCCURRING WITHIN 150 NM EITHER SIDE OF THE BOUNDARY.

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

$$
HUFFMAN
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