[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 131034
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU OCT 13 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
1015 UTC.

...TROPICAL WAVES...

FAR E ATLC TROPICAL WAVE ALONG 22W/23W S OF 14N MOVING W 10 KT.
WAVE IS TILTED MORE SO THAN 6 HOURS AGO. BROAD CYCLONIC ROTATION
IS OBSERVED ON VISIBLE SATELLITE IMAGERY. LARGE AREA OF
SCATTERED MODERATE/STRONG CONVECTION PRECEDES THE WAVE AXIS FROM
8N-14N BETWEEN 22W-30W.

SECOND E ATLC TROPICAL WAVE TILTED N TO SE FROM 7N32W 18N36W
MOVING W 10 KT. WAVE CONTINUES TO BE ALONG THE LEADING EDGE OF A
PLUME OF AFRICAN DUST AND IS STILL BEING AFFECTED BY STRONG
MID-LEVEL EASTERLIES WHICH ARE GIVING THE WAVE ITS TILT. NO
ASSOCIATED DEEP CONVECTION.

CENTRAL ATLC TROPICAL WAVE ALONG 43W/44W S OF 20N DRIFTING W
5-10 KT. WAVE REMAINS IN CLOSE PROXIMITY TO A CLOSE UPPER LOW
NEAR 16N50W. NO ASSOCIATED DEEP CONVECTION.

LOW-AMPLITUDE TROPICAL WAVE E OF THE WINDWARD ISLANDS ALONG 55W
S OF 14N MOVING W 5-10 KT. THE UPPER LOW WHICH IS AFFECTING THE
WAVE ALONG 43W/44W IS ALSO PARTLY AFFECTING THIS WAVE. NO
ASSOCIATED DEEP CONVECTION.

E CARIBBEAN TROPICAL WAVE IS NO LONGER DISCERNIBLE AS IT MOVES
INTO AN AREA OF LOWER PRESSURE AND SURFACE TROUGH.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 16N17W 13N21W...THEN ALONG 10N24W
9N38W 10N42W 10N59W 12N64W. CLUSTERS OF SCATTERED MODERATE/
STRONG CONVECTION ARE WITHIN 150 NM S OF THE AXIS E OF 19W TO
INLAND OVER AFRICA AND WITHIN 150/225 NM S OF THE AXIS FROM
25W-39W. WIDELY SCATTERED CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION DOT THE AREA FROM 3N-15N
BETWEEN 23W-34W AND FROM 4N-10N BETWEEN 44W-53W.

...DISCUSSION...

GULF OF MEXICO...
THE GULF IS COVERED BY A LARGE UPPER LEVEL RIDGE EXTENDING FROM
S/CENTRAL MEXICO NE TO THE JUST OFF THE OUTER BANKS OF NORTH
CAROLINA...ANCHORED BY AN UPPER HIGH IN THE SE GULF N OF THE
YUCATAN CHANNEL NEAR 24N86W. EXCEPT FOR A NARROW SWATH OF UPPER
MOISTURE STREAMING FROM NE MEXICO TOWARDS SE GEORGIA...THE AREA
IS DOMINATED BY MODERATE/STRONG SUBSIDENCE AND FAIR SKIES.
ISOLATED THUNDERSTORMS BEING GENERATED BY A SURFACE TROUGH IN
THE W CARIBBEAN ARE DRIFTING THROUGH THE YUCATAN CHANNEL. A WEAK
FRONTAL BOUNDARY IS EXPECTED TO MOVE OFF THE N GULF COAST INTO
GULF BY THE WEEKEND...PUSHING SLIGHTLY DRIER AIR S OVER THE AREA.

CARIBBEAN...
HEAVY RAIN CONTINUE TO PLAGUE PARTS OF THE CENTRAL AND SW
CARIBBEAN. THE STRONGEST CONVECTION HAVE REMAINED OVER
WATER...BUT ABUNDANT MOISTURE CONTINUES TO BE PUMPED N OVER
HISPANIOLA AND PUERTO RICO THIS MORNING WHICH HAS CAUSED HEAVY
RAINFALL ACCUMULATIONS AND FLOODING PROBLEMS. UPPER LEVEL
OUTFLOW HAS INCREASED OVER THE AREA WITH AN UPPER HIGH CENTERED
NEAR 16N78W AND EASTERLY FLOW ALOFT ADVECTING MUCH OF THE
THUNDERSTORMS TOWARDS CENTRAL AMERICA. A SURFACE TROUGH EXTENDS
THROUGH THE WINDWARD PASSAGE CLOSE TO HAITI SW TO 16N79W TO OVER
NICARAGUA...AND MOST OF THE THUNDERSTORMS ARE OCCURRING S AND E
OF THIS BOUNDARY WITH SCATTERED MODERATE/ISOLATED STRONG
CONVECTION UP TO 300/400 NM TO THE SE. SOME OF THIS HEAVY
ACTIVITY CONTINUES TO MOVE ACROSS THE DOMINICAN REPUBLIC AND
PUERTO RICO. A SECOND SURFACE TROUGH EXTENDS FROM A 1006 MB LOW
S OF THE CAYMAN ISLANDS NEAR 18N81W W TO 18N86W AND IS
TRIGGERING AN AREA OF SCATTERED STRONG CONVECTION NEAR THE COAST
OF THE YUCATAN WITHIN A 60/75 NM RADIUS OF 18N86.5W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS OVER THE FAR NW CARIBBEAN N OF
19N W OF 81W THROUGH THE YUCATAN CHANNEL. THE PATTERN IS STILL
NOT EXPECTED TO CHANGE MUCH OVER THE NEXT 5 DAYS...WHICH WILL
CONTINUE THE THREAT OF HEAVY RAINS AND FLOODING OVER PUERTO RICO
AND HISPANIOLA INTO EARLY NEXT WEEK.

WEST ATLANTIC...
THE SAME WEATHER SYSTEM AFFECTING THE CARIBBEAN CONTINUES
NORTHWARD INTO THE W ATLC WITH A 1006 MB LOW N OF THE REGION
NEAR 34N68W AND A SURFACE TROUGH EXTENDING SE TO A 1003 MB LOW
CENTERED S OF BERMUDA NEAR 30N65W CONTINUING SSW TO THE WINDWARD
PASSAGE. THESE SURFACE FEATURES ARE COLLOCATED WITH A NARROW
UPPER TROUGH FROM AN UPPER LOW NEAR 32N67W ALONG 25N71W TO
20N74W WHICH IS ADVECTING THE DEEP TROPICAL MOISTURE NE ACROSS
HISPANIOLA AND PUERTO RICO. SCATTERED MODERATE/STRONG CONVECTION
IS LOCATED E OF THE TROUGH WITHIN 120 NM OF LINE FROM 20N66W TO
30N60W. DRY AIR THAT FILTERED IN BEHIND THE UPPER TROUGH IS
PRODUCING MAINLY FAIR SKIES W OF 70W TO FLORIDA WEAR A 1009 MB
LOW IS ALONG THE GEORGIA COAST AND A LOW LEVEL SURFACE TROUGH
EXTENDS SSW ACROSS CENTRAL FLORIDA.

EAST/CENTRAL ATLANTIC...
A LARGE CUT-OFF UPPER LEVEL LOW IS OVER THE TROPICS ABOUT 600 NM
E OF THE LEEWARD ISLANDS NEAR 16N51W AND HAS DRAGGED A LARGE
AREA OF DRY AIR S INTO THE UPPER LOW COVERING THE AREA TO ACROSS
THE WINDWARD ISLANDS. ALTHOUGH...THE LOW/TROUGH IS ALSO PULLING
TROPICAL MOISTURE NE INTO THE CENTRAL AND E ATLC WATERS TO 20N E
OF 47W. A SHORTWAVE TROUGH IS ALONG 30N30W TO 23N40W AND IS
INTERACTING WITH A SURFACE TROUGH ALONG 25N30W TO 20N41W
PRODUCING WIDELY SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM
19N-27N BETWEEN 27W-42W. AN UPPER LEVEL HIGH IS CENTERED SE OF
THE CAPE VERDE ISLANDS NEAR 12N22W AND THE DIFFLUENT W SIDE OF
THIS FEATURE APPEARS TO BE ENHANCING CONVECTION ASSOCIATED WITH
THE TROPICAL WAVE ALONG 22W/23W. THE NE TRADES HAVE STRENGTHENED
OVER THE FAR E PART OF THE AREA AND A PLUME OF AFRICAN DUST
CONTINUES TO MAKE ITS WAY ACROSS THE ATLC...MAKING IT AS FAR W
AS 35W/36W.

$$
WALLACE



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