[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 091805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT 09 OCT 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLC 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...

TROPICAL STORM MATTHEW HAS BEEN DOWNGRADED SINCE THE 09/0900 UTC
ADVISORY...TO TROPICAL DEPRESSION MATTHEW...CENTER NEAR 26.7N
92.6W OR ABOUT 270 MILES SOUTHWEST OF THE MOUTH OF THE
MISSISSIPPI RIVER...09/1500 UTC. T.D. MATTHEW IS MOVING
NORTH-NORTHEAST 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE
1003 MB. MAXIMUM SUSTAINED WIND SPEED 30 KT GUSTS 40 KT.
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. STRONG SOUTHWESTERLY
SHEAR REMOVED THE CONVECTION FROM THE CENTER OF CIRCULATION AND
MATTHEW HAS BECOME AN ELONGATED SWIRL OF LOW CLOUDS WITH MOST
OF THE WEATHER WITHIN A BAND LOCATED NORTHEAST AND EAST OF THE
CENTER. AN AIR FORCE PLANE WILL CHECK MATTHEW THIS AFTERNOON.
NO STRENGTHENING IS INDICATED BECAUSE STRONG SHEAR IS FORECAST
TO PERSIST. THE GFDL MODEL INSISTS ON INTENSIFYING MATTHEW
DESPITE THE SHEAR. MATTHEW IS EMBEDDED WITHIN STRONG UPPER LEVEL
SOUTHWESTERLY FLOW...TO THE EAST OF A DEEPENING MIDDLE TO UPPER
LEVEL TROUGH IN THE CENTRAL UNITED STATES AND NORTHWESTERN
MEXICO. THIS PATTERN CONTINUES TO CREATE STRONG SHEAR OVER
MATTHEW. SCATTERED TO NUMEROUS STRONG SHOWERS AND THUNDERSTORMS
FROM 23.5N TO 25N BETWEEN 89W AND 92W...AND FROM 26.5N TO 28.5N
BETWEEN 88.5W AND 92W. ISOLATED MODERATE TO LOCALLY STRONG
SHOWERS ELSEWHERE IN THE SOUTHWESTERN CORNER OF THE GULF OF
MEXICO. LOCALLY HEAVY RAIN IS LIKELY WITHIN THIS AREA DURING
THE WEEKEND PRIOR TO THE ARRIVAL OF MATTHEW LATE SUNDAY/EARLY
MONDAY...GIVEN THE STEADY STREAM OF TROPICAL MOISTURE SURGING
NORTHWARD AND THE IMPROVING MIDDLE TO UPPER LEVEL DYNAMICS
ASSOCIATED WITH THE TROUGH. LOCAL NWS OFFICES IN FACT HAVE
ISSUED FLOOD WATCHES/WARNINGS FROM LOUISIANA TO THE FLORIDA
PANHANDLE IN ANTICIPATION OF THIS EVENT.

A SURFACE 1009 MB LOW PRESSURE CENTER IS NEAR 29N61.5W...WITH
A TROUGH GOING FROM IT TO 23N63W...THROUGH THE MONA PASSAGE...
TO 17.5N68W. DEEP LAYER CYCLONIC FLOW COVERS THE ATLANTIC
OCEAN NORTH OF 20N WEST OF 60W AS UPPER LEVEL ANTICYCLONIC
FLOW FROM THE GULF OF MEXICO UPPER LEVEL RIDGE WHICH SURROUNDS
T.D. MATTHEW. A MIDDLE TO UPPER LEVEL TROUGH STRETCHES FROM
THE MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER...
SOMEWHERE FROM 27N TO 28N BETWEEN 67W AND 68W...TO NORTHERN
COLOMBIA/NORTHWESTERN VENEZUELA. MIDDLE TO UPPER LEVEL DRY
AIR IS IN PLACE IN MUCH OF THE CARIBBEAN SEA WEST OF THIS
TROUGH...EXCEPT FOR SOME HIGH LEVEL MOISTURE MOVING INTO THE
NORTHWESTERN CORNER WITH THE UPPER LEVEL GULF OF MEXICO RIDGE.
UPPER LEVEL RIDGE IN THE ATLANTIC OCEAN EAST OF THIS WESTERN
ATLANTIC DEEP LAYER CYCLONIC FLOW...10N52W 28N51W 35N50W.
SCATTERED STRONG SHOWERS AND THUNDERSTORMS CLOSE TO THE SURFACE
LOW CENTER FROM 31N TO 33N BETWEEN 61W AND 66W. SCATTERED
MODERATE TO STRONG SHOWERS AND THUNDERSTORMS UNDER THE RIDGE
EAST OF THE DEEP LAYER CYCLONIC FLOW FROM 13N TO 19N BETWEEN
53W AND 62W. SOME OF THIS PRECIPITATION EASILY IS REACHING THE
EASTERN CARIBBEAN ISLANDS. BROKEN TO OVERCAST MULTILAYERED
CLOUDS AND OTHER AREAS OF SHOWERS AND POSSIBLE THUNDERSTORMS
COVER THE ATLANTIC WATERS NORTH OF 20N BETWEEN 44W AND 60W.

...TROPICAL WAVES...

TROPICAL WAVE 29W/30W SOUTH OF 20N MOVING WEST 10 KT. LOW CLOUDS
IN THE VISIBLE IMAGERY ARE MOVING CYCLONICALLY FROM 11N TO 18N
BETWEEN 27W AND 33W. SCATTERED MODERATE TO ISOLATED STRONG
SHOWERS AND THUNDERSTORMS FROM 13N TO 16N BETWEEN 25W AND 29W.
THIS WAVE IS MOVING THROUGH THE SOUTHERN END/BASE OF AN EASTERN
ATLANTIC MIDDLE TO UPPER LEVEL TROUGH...WHICH RUNS FROM THE
MADEIRA ISLANDS TO JUST WEST OF THE CANARY ISLANDS...TO JUST
WEST OF THE CAPE VERDE ISLANDS. A GOOD AMOUNT OF MIDDLE TO UPPER
LEVEL DRY AIR IS MIXED IN WITH THIS EASTERN ATLANTIC TROUGH.

TROPICAL WAVE 50W/51W SOUTH OF 20N MOVING WEST 15-20 KT. THE
WAVE SHOWS UP IN THE 09/1200 UTC SURFACE OBSERVATIONS. A CYCLONIC
SWIRL OF LOW CLOUDS IN THE LATEST VISIBLE IMAGERY APPEARS NEAR
13N ALONG 51W/52W. ISOLATED MODERATE TO LOCALLY STRONG SHOWERS
AND THUNDERSTORMS FROM 7N TO 16N BETWEEN 49W AND 56W.

...ITCZ...

ITCZ 12N16W 8N28W 7N41W 8N48W 9N52W 10N64W...AND IN THE
SOUTHWESTERN CARIBBEAN SEA AREA FROM 9N70W TO 10N80W 10N86W.
STRONG SHOWERS IN CLUSTERS IN COASTAL SECTIONS OF AFRICA FROM
THE COAST TO 7N BETWEEN THE PRIME MERIDIAN AND 10W. ISOLATED
MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS FROM 4N TO 8N
BETWEEN 10W AND 20W...FROM 8N TO 10N BETWEEN 34W AND 48W.

...DISCUSSION...

GULF OF MEXICO...
A TROUGH TO RIDGE PATTERN COVERS THE AREA FROM INTERIOR MEXICO
TO THE EASTERN GULF OF MEXICO WATERS. REFER TO THE INFORMATION
FROM THE SECTION ABOUT T.D. MATTHEW FOR MORE INFORMATION.

THE CARIBBEAN SEA...
UPPER LEVEL ANTICYCLONIC FLOW REACHES PARTS OF THE WESTERN
CARIBBEAN SEA. A DEEP LAYER TROUGH...RELATED TO THE 1009 MB
SURFACE LOW PRESSURE CENTER NEAR 29N61.5W AND THE DEEP LAYER
CYCLONIC FLOW...RUNS FROM THE WESTERN ATLANTIC OCEAN INTO THE
EASTERN CARIBBEAN SEA TO NORTHERN COLOMBIA/NORTHWESTERN
VENEZUELA.

SUBTROPICAL ATLANTIC...
REFER TO THE SECTIONS ABOUT THE 1009 MB LOW PRESSURE CENTER
NEAR 29N61.5W...AND THE DEEP LAYER CYCLONIC FLOW.

TROPICAL ATLANTIC...
THE MIDDLE TO UPPER LEVEL EASTERN ATLANTIC TROUGH RUNS FROM
THE MADEIRA ISLANDS TO THE CAPE VERDE ISLANDS. UPPER LEVEL
ANTICYCLONIC IS MORE RESTRICTED TO AFRICA...AND ITS COASTAL
WATERS IMMEDIATELY EAST OF THE THE TROUGH.

$$
MT


This weather bulletin was brought to you by:
www.nashvilleweather.net