[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 151107
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT OCT 15 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1030 UTC.

...SPECIAL FEATURE...

A NOT-WELL DEFINED SURFACE 1005 MB LOW PRESSURE CENTER NOW IS
OFF THE SOUTHWESTERN COAST OF JAMAICA. SCATTERED TO NUMEROUS
STRONG SHOWERS AND THUNDERSTORMS EXTEND FROM 15.5N TO 20N
BETWEEN 74W IN THE WINDWARD PASSAGE TO 81W....FROM HAITI TO
CUBA TO JAMAICA. A SURFACE TROUGH REMAINS FROM SOUTHEASTERN
CUBA...THROUGH THE 1005 MB LOW CENTER...TO EASTERN COASTAL
NICARAGUA...AND THROUGH NICARAGUA TO EASTERN EL SALVADOR.
SURFACE OBSERVATIONS INDICATE THAT IT HAS NOT YET BECOME
A TROPICAL DEPRESSION AS THIS SYSTEM GRADUALLY IS BECOMING
BETTER ORGANIZED. CONDITIONS APPEAR FAVORABLE FOR DEVELOPMENT
AND A TROPICAL DEPRESSION MAY FORM LATER TODAY OR SUNDAY.
THIS SYSTEM IS EXPECTED TO MOVE SLOWLY WEST OR
WEST-NORTHWESTWARD...AND RESIDENTS IN JAMAICA...CUBA...THE
CAYMAN ISLANDS...AND THE REMAINDER OF THE NORTH-CENTRAL AND
NORTHWESTERN CARIBBEAN SEA SHOULD MONITOR ITS PROGRESS CLOSELY.
LOCALLY HEAVY RAINFALL ALSO WILL BE POSSIBLE ACROSS JAMAICA...
SOUTHEASTERN CUBA...AND HAITI.  AN AIR FORCE RESERVE UNIT
RECONNAISSANCE AIRCRAFT IS TENTATIVELY SCHEDULED TO INVESTIGATE
THE SYSTEM LATER TODAY IF NECESSARY.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 37W/38W SOUTH OF 20N MOVING WEST 15 KT.
SCATTERED MODERATE TO ISOLATED STRONG SHOWERS AND THUNDERSTORMS
FROM 10N TO 15N BETWEEN 33W AND 36W. UPPER LEVEL WINDS ARE
SHEARING CLOUD TOPS IN THE AREA FROM 12N TO 16N BETWEEN 25W
AND 31W.

TROPICAL WAVE ALONG 60W/61W SOUTH OF 19N MOVING WEST 10 TO
15 KT. THIS WAVE IS MOVING THROUGH THE AREA OF CYCLONIC FLOW
AROUND THE 17N58W LOW CENTER WHICH IS ABOUT 20060 NM
EAST-NORTHEAST OF GUADELOUPE. ISOLATED MODERATE SHOWERS AND
LOCALLY STRONG THUNDERSTORMS ARE FOUND FROM 10N TO 17N BETWEEN
55W AND 60W.

...ITCZ...

ITCZ 8N13W 6N20W 10N29W 15N34W...10N37W 9N44W 11N49W. SCATTERED
MODERATE TO ISOLATED STRONG SHOWERS AND THUNDERSTORMS FROM 2N
TO 9N BETWEEN 10W AND 30W. ISOLATED MODERATE TO LOCALLY STRONG
SHOWERS AND THUNDERSTORMS FROM 5N TO 10N BETWEEN 34W AND 50W.

...DISCUSSION...

THE GULF OF MEXICO...
THE MIDDLE TO UPPER LEVEL HIGH CENTER NOW IS THE SOUTH CENTRAL
GULF WATERS. MIDDLE TO UPPER LEVEL DRY AIR ACCOMPANIES THIS HIGH
CENTER. A DISSIPATING COLD FRONT EXTENDS FROM THE SOUTHEASTERN
FLORIDA COASTAL LOW CENTER TO SOUTH FLORIDA AND TO WESTERN CUBA.
SHOWERS MAY BE POSSIBLE ALONG THE FRONT. THE EASTERN FLORIDA
COASTAL LOW CENTER NEAR 26.5N 79W IS APPARENT NOW ONLY IN
SURFACE OBSERVATIONS...AND NOT SO OBVIOUS IN SATELLITE IMAGES
DURING THE LATE NIGHT AND EARLY MORNING HOURS. SURFACE
ANTICYCLONIC FLOW AND ADVANCING HIGH PRESSURE COVER THE GULF
WATERS.

THE EASTERN CARIBBEAN SEA AND THE ATLANTIC OCEAN SOUTH OF 25N
BETWEEN 50W AND 63W...
A MIDDLE TO UPPER LEVEL TROUGH IS DIGGING AND HAS BEEN DIGGING
INTO THE EASTERN AND SOUTHEASTERN CARIBBEAN SEA...FROM A MIDDLE
TO UPPER LEVEL LOW CENTER WHICH NOW IS ABOUT 220 NM EAST OF
ANGUILLA NEAR 18N59W. THE TROPICAL WAVE ALONG 60W/61W SOUTH OF
20N IS MOVING THROUGH THE AREA OF MIDDLE TO UPPER LEVEL CYCLONIC
FLOW WITH THIS TROUGH. ISOLATED MODERATE SHOWERS AND LOCALLY
STRONG THUNDERSTORMS ARE FOUND IN THE ATLANTIC WATERS FROM 10N
TO 18N BETWEEN 56W AND 60W...AND LITTLE TO NO DEEP CONVECTIVE
ACTIVITY IN THE CARIBBEAN SEA.

THE WESTERN ATLANTIC OCEAN WEST OF 63W AND NORTH OF 25N
BETWEEN 50W AND 63W...
A MIDDLE TO UPPER LEVEL TROUGH/SHEAR AXIS CONNECTS ONE LOW
CENTER NEAR 38N61W TO A SECOND LOW CENTER ABOUT 280 NM NORTHEAST
OF THE SOUTHERN BAHAMAS NEAR 28N66W. THIS 28N66W CENTER IS
COMPARATIVELY MUCH LESS WELL-DEFINED THAN IT WAS 18 HOURS AGO.
MIDDLE TO UPPER LEVEL DRY AIR IS WEST OF THIS TROUGH. SOME HIGH
LEVEL MOISTURE IS PUSHING ITS WAY INTO THE AREA FROM HISPANIOLA
NORTHWARD. THE SURFACE SCENARIO IS FULL OF LOW CENTERS AND
TROUGHS AND FRONTAL BOUNDARIES. ONE SUCH FRONTAL BOUNDARY PASSES
THROUGH 30N62W TO 27N70W. A DISSIPATING COLD FRONT GOES FROM
27N70W TO THE EASTERN FLORIDA COASTAL LOW CENTER. A DISSIPATING
COLD FRONT EXTENDS FROM THIS LOW CENTER TO SOUTH FLORIDA AND
WESTERN CUBA. BROKEN TO OVERCAST LOW AND MIDDLE LEVEL CLOUDS ARE
NORTH OF THIS FRONT. A TROUGH RUNS FROM A 1005 MB LOW CENTER
NEAR 32N59W TO 23N70W THROUGH THE WINDWARD PASSAGE. UPPER LEVEL
ANTICYCLONIC FLOW AND ISOLATED MODERATE SHOWERS WITHIN 60 NM ON
EITHER SIDE OF 26N62W 21N66W 20N71W. SCATTERED MODERATE TO
STRONG SHOWERS AND THUNDERSTORMS ARE IN BETWEEN THE 38N61W
28N66W TROUGH AND THE CYCLONIC FLOW AROUND THE 18N59W LOW CENTER
EAST OF GUADELOUPE. FROM 27N TO 30N BETWEEN 55W AND 61W.

THE REST OF THE ATLANTIC OCEAN...EAST OF 50W...
A DEEP LAYER TROUGH HAS DUG INTO THE AREA FROM NORTH OF 30N.
THE TROUGH IS SUPPORTING A COLD FRONT WHICH PASSES THROUGH
33N20W TO 28N30W...AND THEN IS STATIONARY FROM 28N30W TO 27N40W
AND BEYOND 31N51W. A 280 TO 360 NM WIDE BAND OF MULTILAYERED
CLOUDS AND POSSIBLE SHOWERS AND THUNDERSTORMS MARKS THIS FRONT.
AN ALREADY-EXISTING SURFACE TROUGH STRETCHES FROM 28N22W TO
25N30W TO A SURFACE 1015 MB LOW PRESSURE CENTER NEAR 24N41W.
THE TROUGH CONTINUES TO 20N50W. THE CLOUDS FROM THE FRONT APPEAR
TO BE COVERING THE CLOUDINESS FROM THE TROUGH.

$$
MT



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