[Tropical] Tropical Weather Discussion

[Nashville EMWIN]

AXNT20 KNHC 181045
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED 18 AUG 2004

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...

HURRICANE DANIELLE IS CENTERED NEAR 27.9N 40.7W AT 18/0900 UTC
MOVING NORTH AT 12 KT.  MAXIMUM SUSTAINED WIND SPEED HAS
DECREASED TO 65 KT WITH GUSTS TO 80 KT AND THE ESTIMATED MINIMUM
CENTRAL PRESSURE IS 985 MB.  SEE LATEST NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.
DANIELLE CONTINUES TO EXPERIENCE STRONG SW SHEAR AND THE LOW
LEVEL CIRCULATION IS NOW PARTIALLY EXPOSED.  THE CLOUD/
CONVECTIVE PATTERN HAS BECOME VERY ASYMMETRIC AND CLOUD TOP
TEMPERATURES ARE RAPIDLY WARMING. DANIELLE IS EXPECTED TO
CONTINUE WEAKENING OVER THE NEXT FEW DAYS AS IT TURNS EWD AROUND
THE N PERIPHERY OF MID-LEVEL RIDGE OVER THE E ATLC. SCATTERED
MODERATE CONVECTION FROM 27N-31N BETWEEN 35W-41W.

...TROPICAL WAVES...

TROPICAL WAVE OVER THE E ATLC ALONG 35W/36W S OF 17N MOVING W
NEAR 15 KT. IR SATELLITE IMAGERY SHOWS AN AREA OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION W OF THE WAVE FROM 6N-11N
BETWEEN 34W-42W.  HOWEVER...THERE IS LITTLE INDICATION OR
ORGANIZATION AT THIS TIME.

TROPICAL WAVE APPROXIMATELY 400 NM E OF THE BARBADOS 53W S OF
15N MOVING W NEAR 15-20 KT. ONLY WIDELY SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS ACCOMPANY THE WAVE FROM 9N-12N BETWEEN
52W-60W.

TROPICAL WAVE...REMNANTS OF T.S. EARL...OVER HONDURAS/NICARAGUA
ALONG 86W S OF 20N MOVING W 20 TO 25 KT.  ASSOCIATED CONVECTION
HAS INCREASED OVERNIGHT BUT REMAINS UNORGANIZED.  SCATTERED
MODERATE CONVECTION FROM 11N-18N BETWEEN 82W-88W.

...ITCZ...
ITCZ AXIS ALONG 11N10W 8N25W 12N38W 7N60W 6N70W 7N80W.
SCATTERED MODERATE OVER NW COLOMBIA FROM 3N-8N BETWEEN 72W-77W.

...DISCUSSION...
GULF OF MEXICO...
MID/UPPER LEVEL RIDGE REMAINS OVER THE GLFMEX EXTENDING FROM THE
BAY OF CAMPECHE NEWD THROUGH THE FLORIDA STRAITS.  THE RIDGE
CONTINUES TO KEEP UPSTREAM DISTURBANCES N OF THE AREA AND
PRODUCE GENERALLY TRANQUIL WEATHER. FURTHER S...A RETROGRADING
MID/UPPER LOW OVER THE NW CARIBBEAN IS UNDERCUTTING THE RIDGE
AND PRODUCING SHOWERS/THUNDERSTORMS OVER THE SE GLFMEX AND
FLORIDA STRAITS. THE UPPER LOW WILL CONTINUE TO SPARK
CLOUDS/CONVECTION AS IT DRIFTS SLOWLY NW AND WEAKENS OVER THE SE
GLFMEX DURING THE NEXT 24-36 HOURS. AT THE SURFACE...HIGH PRES
OVER THE S UNITED STATES NOSES SWD INTO THE N GLFMEX WITH
GENERALLY ELY FLOW OVER THE ENTIRE AREA.

CARIBBEAN SEA...
THE PRIMARY WEATHER MAKER OVER THE CARIBBEAN IS A STRONG
TROPICAL WAVE MOVING OVER CENTRAL AMERICA ALONG 86W. THE WAVE IS
INTERACTING WITH A MID/UPPER LEVEL LOW OVER THE NW CARIBBEAN AND
PRODUCING WIDELY SCATTERED TO LOCALLY SCATTERED MODERATE
CONVECTION OVER PORTIONS OF CENTRAL AMERICA FROM NW COSTA RICA
TO EL SALVADOR AND HONDURAS. OVER THE E CARIBBEAN... SUBSIDENCE
AND VERY DRY MIDDLE TO UPPER LEVEL AIR DOMINATES E OF 80W
PRODUCING AN UNUSUAL ABSENCE OF CLOUDS/CONVECTION.

SUBTROPICAL ATLANTIC...
THERE HAS BEEN LITTLE CHANGE IN THE OVERALL MID-UPPER LEVEL
PATTERN DURING THE LAST 24 HOURS WITH A REX TYPE BLOCKING REGIME
DOMINATING THE AREA. THE REX BLOCK IS COMPRISED OF A RIDGE OVER
THE W ATLC EXTENDING FROM THE BAHAMAS NEWD OVER BERMUDA
CONTINUING EWD OVER THE CENTRAL ATLC POLEWARD OF A LARGE
MID/UPPER LEVEL LOW NEAR 31N50W. E OF THE UPPER LOW...A
MID/UPPER LEVEL RIDGE EXTENDS N/S ALONG 32W.  MOST OF THE
UPSTREAM DYNAMICS AND MOISTURE IS RIDING UP AND OVER THE W ATLC
RIDGE LEAVING DRY AIR AND TRANQUIL WEATHER OVER THE W HALF OF
THE ATLC. THE EXCEPTION IS ALONG THE E COAST OF FLORIDA WHERE
SOME ISOLATED CONVECTION IS OCCURRING OVER THE GULF STREAM.
FURTHER E...THERE IS JUST ENOUGH INSTABILITY ASSOCIATED WITH THE
CENTRAL ATLC COLD CORE LOW TO PRODUCE AN AREA OF SCATTERED
SHOWERS/TSTMS N OF 25N BETWEEN 47W-60W.  THE FLOW BECOMES MORE
CONFLUENT S OF THE UPPER LOW PRODUCING STRONG SUBSIDENCE AND
VERY DRY AIR IN THE MIDDLE AND UPPER LEVELS S OF 25N BETWEEN
40-70W. OVER THE E ATLC...HURRICANE DANIELLE CONTINUES TO LIFT
NWD AROUND THE W PERIPHERY OF A MID-UPPER LEVEL RIDGE ALONG 32W.
HOWEVER...THE HURRICANE IS NOW UNDER THE INFLUENCE OF STRONG SW
SHEAR AND IS RAPIDLY WEAKENING. FURTHER E...A SHORTWAVE TROUGH
IS DIGGING SEWD OVER THE CANARY ISLANDS INTO NW AFRICA.
ASSOCIATED SUBSIDENCE AND DRY AIR PREVAILS E OF 30W.  AT THE
SURFACE...DANIELLE IS DISRUPTING THE E PORTION OF THE
SUBTROPICAL RIDGE WITH THE W EXTENT ENTERING THE AREA ALONG
32N50W AND EXTENDING SW TO N FLORIDA.

TROPICAL ATLANTIC...
MID/UPPER LEVEL TROUGH OVER THE CENTRAL SUBTROPICAL ATLC DROPS
SWD INTO THE TROPICAL ATLC THROUGH 20N50W TO THE SE CARIBBEAN.
ASSOCIATED STRONG SUBSIDENCE CONTINUES TO BLANKET A LARGE
PORTION OF THE AREA N OF THE ITCZ BETWEEN 45W-60W. FURTHER
E...MID-UPPER LEVEL RIDGE EXTENDS SWD THROUGH 20N37W 12N55W INTO
S AMERICA NEAR E VENEZUELA.  THIS REGIME IS PRODUCING DEEP ELY
FLOW OVER THE TROPICAL REGIONS E OF 45W.  HOWEVER...CONFLUENT
FLOW AND SUBSIDENCE ASSOCIATED WITH A SHORTWAVE TROUGH ALONG THE
NW COAST OF AFRICA APPEARS TO BE LIMITING SIGNIFICANT TROPICAL
WAVE DEVELOPMENT.

$$
RHOME




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