[Tropical] Tropical Weather Discussion

[Nashville EMWIN]

AXNT20 KNHC 180543
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0415 UTC.

...SPECIAL FEATURES...

HURRICANE DANIELLE IS CENTERED NEAR 26.5N 40.6W AT 18/0300 UTC
MOVING NORTH AT 12 KT.  MAXIMUM SUSTAINED WIND SPEED IS 80 KT
WITH GUSTS TO 100 KT AND THE ESTIMATED MINIMUM CENTRAL PRESSURE
IS 978 MB.  SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.  DANIELLE IS NOW
EXPERIENCING STRONG SW SHEAR AND THE CLOUD/CONVECTIVE PATTERN
HAS BECOME VERY ASYMMETRIC. CLOUD TOP TEMPERATURES ARE RAPIDLY
WARMING AND MID-UPPER LEVEL DRY AIR IS INFRINGING UPON THE SW
PORTION OF THE STORM.  UPPER LEVEL OUTFLOW IS NOW COMPLETELY
RESTRICTED OVER THE SW SEMICIRCLE AND 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. NUMEROUS
MODERATE CONVECTION FROM 26N-28N BETWEEN 37W-40W. SCATTERED
MODERATE CONVECTION ELSEWHERE FROM 27N-31N BETWEEN 38W-42W.

...TROPICAL WAVES...

TROPICAL WAVE OVER THE E ATLC ALONG 34W S OF 17N MOVING W NEAR
15 KT. IR SATELLITE IMAGERY SHOWS AN AREA OF NUMEROUS STRONG
CONVECTION W OF THE WAVE FROM 7N-11N BETWEEN 36W-41W.
HOWEVER...THIS ACTIVITY IS PROPAGATING RAPIDLY WESTWARD AWAY
FROM THE WAVE INDICATING LITTLE ORGANIZATION.

TROPICAL WAVE APPROXIMATELY 450 NM E OF THE BARBADOS 52W S OF
15N MOVING W NEAR 15-20 KT. A SMALL AREA OF SCATTERED MODERATE
CONVECTION ACCOMPANIES THE WAVE FROM 9N-11N BETWEEN 50W-54W.
THERE ARE NO SIGNS OF DEVELOPMENT.

TROPICAL WAVE...REMNANTS OF T.S. EARL...OVER THE W CARIBBEAN
NEAR THE COAST OF HONDURAS/NICARAGUA ALONG 84W S OF 20N MOVING W
20 TO 25 KT.  ASSOCIATED CONVECTION HAS INCREASED SINCE THIS
TIME YESTERDAY BUT REMAINS UNORGANIZED.  WIDELY SCATTERED TO
LOCALLY SCATTERED MODERATE CONVECTION FROM 10N-19N BETWEEN
81W-88W.

...ITCZ...
ITCZ AXIS ALONG 11N10W 8N25W 12N38W 7N60W 6N70W 7N80W.  WIDELY
SCATTERED MODERATE CONVECTION OVER VENEZUELA WITHIN 120 NM
EITHER SIDE OF AXIS. SCATTERED MODERATE TO STRONG CONVECTION
OVER COLOMBIA FROM 5N-10N BETWEEN 72W-80W.

...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.  WEAK DIVERGENCE ALOFT
ENHANCED EARLIER SEABREEZE CONVECTION OVER INTERIOR PORTIONS OF
FLORIDA BUT THIS ACTIVITY HAS SINCE WEAKENED.  FURTHER S...A
RETROGRADING MID/UPPER LOW OVER THE NW CARIBBEAN IS PRODUCING
INCREASING SHOWERS/THUNDERSTORMS OVER THE SE GLFMEX AND FLORIDA
STRAITS. THE UPPER LOW WILL CONTINUE TO SPARK CLOUDS/CONVECTION
AS IT DRIFTS SLOWLY NW AND WEAKEN 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 INTO CENTRAL AMERICA ALONG 84W. THE WAVE
CONTINUES TO PRODUCE STRONG GUSTY WINDS E OF THE AXIS TO 70W.
THE WAVE IS ALSO 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
80 PRODUCING AN UNUSUAL ABSENCE OF CLOUDS/CONVECTION SAVE A FEW
ISOLATED THUNDERSTORMS NEAR HISPANIOLA AND PUERTO RICO.

SUBTROPICAL ATLANTIC...
THERE HAS BEEN LITTLE CHANGE IN THE OVERALL MID-UPPER LEVEL
PATTERN DURING THE LAST 24 HOURS WITH A BLOCKED REX TYPE 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 31N49W. 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 RESIDUAL AFTERNOON AND EVENING CONVECTION LINGERS.  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 SW SHEAR AND IS
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 32N55W AND EXTENDING SW TO CENTRAL
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 AN AMPLIFYING TROUGH ALONG
THE NW COAST OF AFRICA APPEARS TO BE LIMITING SIGNIFICANT
TROPICAL WAVE DEVELOPMENT.

$$
RHOME



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