[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 170557
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON OCT 17 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...SPECIAL FEATURE...

TROPICAL DEPRESSION TWENTY-FOUR IS CENTERED NEAR 17.4N 79.6W AT
17/0600 UTC OR 150 NM SE OF GRAND CAYMAN MOVING W AT 2 KT.
MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB. SEE THE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24
KNHC AND THE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/
WTNT34 KNHC FOR MORE DETAILS. DEEP CONVECTION HAS BLOSSOMED TO
THE S OF THE CENTER DURING THE PAST 6 HOURS. NUMEROUS STRONG
CONVECTION IS WITHIN 60 NM OF LINE FROM 17N79W TO 15N82W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION IN THE
FORM OF RAINBANDS TO THE E OF THE CENTER DOT THE AREA FROM
10N-20N BETWEEN 70W-80W. AT THE UPPER LEVELS...UPPER HIGH WITH
GOOD OUTFLOW IS TO THE E OF THE CENTER. DRY UPPER AIR IS
ENCROACHING INTO T.D. TWENTY-FOUR FROM THE NW...THUS LIMITING
CONVECTION AND OUTFLOW.

...TROPICAL WAVES...

CENTRAL ATLC WAVE IS TILTED NE/SW FROM 18N39W THROUGH A 1010 MB
LOW NEAR 14.5N42.5W TO 7N48W. WAVE IS MOVING OUT OF AN AREA OF
SLIGHTLY DRIER UPPER AIR...THUS CONVECTION IS TO THE W OF THE
WAVE. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM W OF THE
LOW AND SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN
75 NM OF 11N W OF THE WAVE TO 50W.

CENTRAL CARIBBEAN WAVE IS ALONG 71W/72W S OF 17N MOVING W 10 KT.
THIS WAVE CONTINUES TO BE DIFFICULT TO TRACK AND MAY ULTIMATELY
DISSIPATE AS IT APPROACHES T.D. TWENTY-FOUR. WAVE IS BENEATH
UPPER LEVEL S FLOW OF THE UPPER HIGH NEAR T.D. TWENTY-FOUR.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N14W 8N21W 11N38W THEN ALONG
13N46W 10N60W. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 60
NM OF THE AXIS FROM 48W-52W. CLUSTERS OF SIMILAR CONVECTION ARE
WITHIN 400 NM S OF THE AXIS FROM 27W-33W AND FROM 7N-11N BETWEEN
33W-38W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE WITHIN 120/150 NM OF 5N FROM 33W-42W AND WITHIN
180 NM N OF THE AXIS FROM 51W-56W.

...DISCUSSION...

GULF OF MEXICO...
CLEAR SKIES REIGN ALONG THE N GULF COAST DESPITE THE PRESENCE OF
A WEAK COLD FRONT. COLD FRONT EXTENDS FROM THE W ATLC ACROSS N
FLORIDA THROUGH A 1011 MB LOW CENTERED NEAR 30N83W CONTINUING W
TO INLAND OVER SE LOUISIANA. THE FRONT IS DELINEATED BY A
DRASTIC DROP IN DEW POINTS OF 25 TO 30 DEGREES F. SCATTERED LOW/
MID CLOUDS DOT THE GULF S OF 26N WITH BROKEN/OVERCAST LOW CLOUDS
AND ISOLATED SHOWERS S OF 25N TO CUBA BETWEEN 81W-84W INCLUDING
THE FLORIDA KEYS. AT THE UPPER LEVELS...UPPER HIGH ANCHORED N OF
THE BAY OF CAMPECHE NEAR 22N93W DOMINATES THE GULF WITH
MODERATE/STRONG SUBSIDENCE. MOSTLY DRY CONDITIONS ARE LIKELY
THROUGH MID WEEK WITH A SLIGHT CHANCE OF SHOWERS IN THE BAY OF
CAMPECHE AND AN INCREASE IN RAIN CHANCE FOR S FLORIDA AS T.D.
TWENTY-FOUR MOVES INTO THE NW CARIBBEAN.

CARIBBEAN SEA...
BIGGEST WEATHER MAKER FOR THE ATLC BASIN IS THE DEVELOPING T.D.
TWENTY-FOUR IN THE W CARIBBEAN. UPPER HIGH IS JUST TO THE E OF
THE DEPRESSION WITH RIDGING EXTENDING E TO JUST S OF PUERTO
RICO. HEAVY RAIN CONTINUES TO BE A CONCERN AS AN INFLOW BAND ON
THE E SIDE OF THE SYSTEM LIES FROM HISPANIOLA WESTWARD TO OVER E
CUBA AND JAMAICA. RAINBANDS WILL SHIFT WESTWARD AS THE
DEPRESSION MOVES DRIFTS WESTWARD. SEE SPECIAL FEATURES FOR MORE
DETAILS. THE FAR NW CARIBBEAN IS UNDER THE INFLUENCE OF THE
BROAD UPPER HIGH AND STRONG SUBSIDENCE OF THE GULF COVERING W
CUBA AND THE YUCATAN PENINSULA. THE E CARIBBEAN IS UNDER S UPPER
FLOW FROM AN UPPER LOW JUST E OF THE LEEWARD ISLANDS. DIFFLUENCE
IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS E OF 70W
WITH ONLY ISOLATED SHOWERS OVER THE LESSER ANTILLES. A SURGE OF
MOISTURE AND ACCOMPANYING SHOWERS/THUNDERSTORMS SHOULD HIT THE
WINDWARD ISLANDS LATER THIS MORNING.

ATLANTIC OCEAN...
DEEP LAYERED TROUGH IS OVER THE W ATLC N OF 27N W OF 60W WITH AN
ASSOCIATED COLD FRONT EXTENDING THROUGH 32N73W TO INLAND OVER NE
FLORIDA TO A 1011 MB LOW CENTERED NEAR 30N83W. A WEAK SURFACE
TROUGH EXTENDS FROM S OF BERMUDA NEAR 31N64W WSW TO 28N75W. THE
W ATLC IS DOMINATED BY STRONG SUBSIDENCE AND DRY AIR AT ALL
LEVELS LEAVING THE AREA N OF 28N MOSTLY CLEAR WITH NO SHOWER
ACTIVITY. THE UPPER HIGH ASSOCIATED WITH T.D. TWENTY-FOUR
EXTENDS A RIDGE THROUGH THE WINDWARD PASSAGE NE TO 25N69W WITH
THE UPPER DIFFLUENCE GENERATING CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION S OF 26N FROM 70W-79W
INCLUDING MOST OF THE BAHAMA ISLANDS. THIS IS ALSO GIVING
HISPANIOLA MORE HEAVY RAIN WHICH HAS PLAGUED THE AREA FOR THE
PAST WEEK. BROAD UPPER HIGH OVER THE CENTRAL ATLC IS CENTERED
NEAR 28N49W COVERING THE AREA N OF 20N BETWEEN 40W-56W. AN UPPER
LOW IS JUST TO E THE LEEWARD ISLANDS NEAR 19N61W WITH AN UPPER
TROUGH EXTENDING S TO 15N60W. DIFFLUENCE TO THE E OF THE UPPER
LOW IS GENERATING A SMALL AREA OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION WITHIN A 60 NM RADIUS OF 18.5N58.5W. DEEP
LAYERED TROUGH EXTENDS THROUGH THE MADEIRA ISLANDS SW ALONG
27N24W 22N32W TO A SMALL...WEAK UPPER LOW NEAR 22N38W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS NEAR THE UPPER LOW WITHIN
A 45 NM RADIUS OF 22.5N37W. A DISSIPATING COLD FRONT EXTENDS
ACROSS THE CANARY ISLANDS WITH A SECOND SURGE/COLD FRONT STILL N
OF THE REGION. OVER THE E TROPICAL ATLC...BROAD RIDGING FROM OFF
AFRICA EXTENDS NEAR 14N16W W TO 10N34W. DIFFLUENCE TO THE N...TO
THE S OF THE DEEP LAYERED TROUGH IS GENERATING OVERCAST CLOUDS
WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 150/180 NM
OF LINE FROM 21N26W ACROSS THE CANARY ISLANDS TO 30N13W.

$$
WALLACE


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