[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 211045
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON SEP 21 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURES...

THE CENTER OF TROPICAL STORM IDA AT 21/0900 UTC IS NEAR 19.8N
47.3W. IDA IS MOVING TOWARD THE NORTH-NORTHWEST...OR 330
DEGREES...7 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 IDA ARE BEING
ISSUED UNDER THE WMO HEADER WTNT35 KNHC...AND UNDER THE AWIPS
HEADER MIATCPAT5. FORECAST/ADVISORIES ABOUT TROPICAL STORM IDA
ARE BEING ISSUED UNDER THE WMO HEADER WTNT25 KNHC...AND UNDER
THE AWIPS HEADER MIATCMAT5. CONVECTIVE PRECIPITATION...NUMEROUS
STRONG WITHIN A RADIUS OF 180 NM FROM THE CENTER IN THE EASTERN
SEMICIRCLE. SCATTERED STRONG WITHIN A RADIUS OF 380 NM FROM THE
CENTER IN THE EASTERN QUADRANT. ISOLATED MODERATE ELSEWHERE FROM
15N TO 24N BETWEEN 40W AND 51W.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 18W/19W FROM 17N
SOUTHWARD...JUST EMERGING FROM THE COAST OF AFRICA. CONVECTIVE
PRECIPITATION...SCATTERED STRONG WITHIN 30 NM ON EITHER SIDE OF
16N17W 14N19W 12N20W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH PASSES THROUGH COASTAL SECTIONS OF SENEGAL
NEAR 15N17W TO 10N22W 06N28W 06N37W. NO ITCZ IS PRESENT AT THIS
MOMENT. CONVECTIVE PRECIPITATION...ISOLATED MODERATE FROM 04N TO
08N BETWEEN 10W AND 17W. ISOLATED MODERATE TO LOCALLY STRONG
FROM 05N TO 08N BETWEEN 27W AND 40W. WIDELY SCATTERED MODERATE
TO ISOLATED STRONG FROM 08N TO 12N BETWEEN 48W AND 52W.

...DISCUSSION...

THE GULF OF MEXICO...

BROAD UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE GULF OF
MEXICO TO THE NORTH AND NORTHWEST OF THE ATLANTIC OCEAN-TO-
STRAITS OF FLORIDA TROUGH...AND TO THE NORTH OF THE AREA OF
CYCLONIC WIND FLOW THAT IS ASSOCIATED WITH THE EASTERN PACIFIC
OCEAN 15N104W CYCLONIC CIRCULATION CENTER. COMPARATIVELY DRIER
AIR IN SUBSIDENCE IS APPARENT IN WATER VAPOR IMAGERY IN THE AREA
OF ANTICYCLONIC WIND FLOW. CLOUDS AND POSSIBLE RAINSHOWERS ARE
TO THE SOUTH OF 25N82W 22N98W...AND TO THE NORTH OF 24N.

A COLD FRONT/STATIONARY FRONT IS INLAND...BETWEEN GEORGIA AND
EAST TEXAS. A SURFACE TROUGH IS ALONG THE FLORIDA WEST COAST.

AN EASTERN PACIFIC OCEAN MIDDLE LEVEL TO UPPER LEVEL CYCLONIC
CIRCULATION CENTER IS NEAR 15N104W. CYCLONIC WIND FLOW THAT IS
MOVING AROUND THE CENTER COVERS MEXICO AND THE SOUTHWESTERN
CORNER OF THE GULF OF MEXICO FROM 23N SOUTHWARD...FROM 92W
WESTWARD.

A DIURNAL SURFACE TROUGH EXTENDS FROM THE WESTERN PART OF THE
YUCATAN PENINSULA TO THE EASTERN PART OF THE ISTHMUS OF
TEHUANTEPEC OF SOUTHERN MEXICO. CONVECTIVE PRECIPITATION...
ISOLATED MODERATE TO LOCALLY STRONG IS INLAND BETWEEN 87W IN
HONDURAS AND 97W IN THE ISTHMUS OF TEHUANTEPEC OF SOUTHERN
MEXICO.

THE CARIBBEAN SEA...

AN UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR 14N78W.
CYCLONIC WIND FLOW THAT IS MOVING AROUND THE 14N78W CENTER
COVERS THE CARIBBEAN SEA BETWEEN 70W AND 84W. CONVECTIVE
PRECIPITATION...ISOLATED MODERATE TO LOCALLY STRONG FROM 16N
SOUTHWARD BETWEEN 74W AND CENTRAL AMERICA.

CONVECTIVE PRECIPITATION...WIDELY SCATTERED MODERATE TO ISOLATED
STRONG COVERS THE NORTHWESTERN CORNER OF THE AREA...TO THE WEST
AND NORTHWEST OF THE LINE THAT RUNS FROM 21N80W TO THE EASTERN
COAST OF HONDURAS. UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE
NORTHWESTERN CORNER OF THE AREA.

AN UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR 22N60W.
CYCLONIC WIND FLOW THAT IS MOVING AROUND THE CENTER COVERS THE
ATLANTIC OCEAN FROM 10N TO 32N BETWEEN 50W IN THE ATLANTIC
OCEAN AND 70W IN THE CARIBBEAN SEA.

THE 24-HOUR RAINFALL TOTALS IN INCHES FOR THE PERIOD ENDING AT
21/0000 UTC...ACCORDING TO THE PAN AMERICAN TEMPERATURE AND
PRECIPITATION TABLES...MIATPTPAN/SXCA01 KNHC...ARE 0.11 IN
TEGUCIGALPA IN HONDURAS...0.05 IN BERMUDA...AND 0.02 IN HAVANA
CUBA.

...HISPANIOLA...

UPPER LEVEL NORTHERLY WIND FLOW IS REACHING THE ISLAND...PARTLY
WITH THE CYCLONIC FLOW THAT IS MOVING AROUND THE 22N60W ATLANTIC
OCEAN CYCLONIC CIRCULATION CENTER. UPPER LEVEL SOUTHEASTERLY
WIND FLOW ALSO IS REACHING THE ISLAND...WITH THE FLOW THAT IS
MOVING AROUND THE 14N78W CYCLONIC CIRCULATION CENTER. CONVECTIVE
PRECIPITATION...WARMING CLOUD TOP TEMPERATURES...DISSIPATING/
WEAKENING PRECIPITATION...AND CONVECTIVE DEBRIS CLOUDS ARE IN
THE COASTAL WATERS OF WESTERN HAITI AND IN SOUTHERN HAITI.
ISOLATED MODERATE WITHIN A 15 TO 30 NM RADIUS OF 18N72.5W IN
SOUTHERN HAITI.

CURRENT CONDITIONS...IN THE DOMINICAN REPUBLIC...FEW LOW LEVEL
CLOUDS IN SANTO DOMINGO AND PUNTA CANA. SCATTERED LOW LEVEL
CLOUDS ARE IN SANTIAGO AND PUERTO PLATA.

THE GFS MODEL FORECAST FOR 250 MB SHOWS THAT THE EASTERN HALF OF
THE ISLAND WILL RECEIVE NORTHERLY WIND FLOW AND THE WESTERN HALF
WILL RECEIVE SOUTHERLY WIND FLOW...BECAUSE OF THE 22N60W
CYCLONIC CENTER AND THE 14N78W CYCLONIC CENTER. ANTICYCLONIC
WIND FLOW IS FORECAST TO BUILD FROM THE SOUTH AND A RIDGE WILL
COVER HISPANIOLA FOR THE REST OF DAY ONE OF THE 48-HOUR FORECAST
PERIOD. THE SAME RIDGE WILL CONTINUE ACROSS THE AREA FOR THE
REST OF THE TIME. THE GFS MODEL FORECAST FOR 500 MB SHOWS THAT
ANTICYCLONIC WIND FLOW WILL COVER THE AREA FOR FIRST 24 HOURS.
NORTHERLY WIND FLOW WILL COVER HISPANIOLA FOR DAY TWO OF THE 48-
HOUR FORECAST PERIOD. THE ATLANTIC OCEAN CYCLONIC CENTER IS
FORECAST TO BE NEAR 23N65W. AN ANTICYCLONIC CIRCULATION CENTER
IS FORECAST TO BE NEAR 22N75W. THE GFS MODEL FOR 700 MB STARTS
WITH HISPANIOLA RECEIVING NORTHEAST-TO-EAST WIND FLOW...BEING ON
THE WESTERN SIDE OF AN INVERTED TROUGH. THE WIND FLOW VARIES
FROM EAST-SOUTHEAST...FROM THE NORTHEAST...AND FROM THE
SOUTHEAST AGAIN...DURING DAY TWO...AS AN INVERTED TROUGH SPANS
PUERTO RICO.

THE ATLANTIC OCEAN...

PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR MORE DETAILS
ABOUT TROPICAL STORM IDA.

AN UPPER LEVEL TROUGH PASSES THROUGH 32N72W TO 29N73W...INTO THE
STRAITS OF FLORIDA...TO WESTERN CUBA...TOWARD THE NORTHEASTERN
COAST OF THE YUCATAN PENINSULA OF MEXICO. A SURFACE TROUGH
EXTENDS FROM A 1007 MB LOW PRESSURE CENTER THAT IS NEAR
32N72W...TO 29N73W...TO THE NORTHERN BAHAMAS NEAR 25N78W.
CONVECTIVE PRECIPITATION...WIDELY SCATTERED TO SCATTERED
MODERATE AND ISOLATED STRONG FROM 26N NORTHWARD BETWEEN 66W AND
73W. ISOLATED MODERATE FROM 20N TO 26N BETWEEN 74W AND THE
STRAITS OF FLORIDA...AND FROM 20N NORTHWARD BETWEEN 80W AND THE
YUCATAN PENINSULA IN THE NORTHWESTERN CORNER OF THE CARIBBEAN
SEA.

AN UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR 22N60W.
CYCLONIC WIND FLOW THAT IS MOVING AROUND THE CENTER COVERS THE
ATLANTIC OCEAN FROM 10N TO 32N BETWEEN 50W IN THE ATLANTIC OCEAN
AND 70W IN THE CARIBBEAN SEA. A 1010 MB LOW PRESSURE CENTER IS
NEAR 19N54W. CONVECTIVE PRECIPITATION...SCATTERED STRONG WITHIN
A 30 NM RADIUS OF 24N57W...AND FROM 26N TO 28N BETWEEN 50W AND
52W. ISOLATED MODERATE IS ELSEWHERE FROM 20N NORTHWARD BETWEEN
40W AND 67W. RAINSHOWERS ARE POSSIBLE ALSO FROM 14N NORTHWARD
BETWEEN 60W AND 70W IN THE CARIBBEAN SEA.

AN UPPER LEVEL TROUGH EXTENDS FROM A 32N18W CYCLONIC CIRCULATION
CENTER...TOWARD THE CAPE VERDE ISLANDS. CONVECTIVE
PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG FROM 30N
NORTHWARD BETWEEN 30W AND 34W. RAINSHOWERS ARE POSSIBLE IN
SCATTERED TO BROKEN STRATIFORM CLOUDS THAT COVER THE AREA FROM
20N NORTHWARD BETWEEN 19W AND 40W.

SURFACE ANTICYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN TO THE
NORTH OF THE LINE THAT PASSES THROUGH 32N14W TO 2036W AND BEYOND
32N54W.

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

$$
MT
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