[Tropical] Tropical Weather Discussion

[Nashville EMWIN]

AXNT20 KNHC 172346
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE 17 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

HURRICANE DANIELLE IS CENTERED NEAR 25.8N 40.5W AT 17/2100 UTC
MOVING NORTH AT 16 KT.  MAXIMUM SUSTAINED WIND SPEED IS 85 KT
WITH GUSTS TO 105 KT AND THE ESTIMATED MINIMUM CENTRAL PRESSURE
IS 974 MB.  SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.  DANIELLE IS
EXPERIENCING SW SHEAR. THE CONVECTIVE PATTERN IS BECOMING LESS
SYMMETRIC AND UPPER LEVEL OUTFLOW IS NOW RESTRICTED OVER THE W
SEMICIRCLE. INCREASING SHEAR IS EXPECTED TO WEAKEN DANIELLE OVER
THE NEXT FEW DAYS AS IT MOVES AROUND THE W PERIPHERY OF
MID-LEVEL RIDGE ALONG 20N. NUMEROUS STRONG CONVECTION IS FROM
25N-26N BETWEEN 40W-41W.  SCATTERED MODERATE CONVECTION EXTENDS
FROM 25N-28N BETWEEN 37W-42W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 30W S OF 17N MOVING W NEAR 20 KT. LATEST
IR SATELLITE IMAGERY SHOWS CONVECTION W OF THE WAVE AXIS WITH
SCATTERED MODERATE TO STRONG CONVECTION FROM 8N-11N BETWEEN
33W-36W.

TROPICAL WAVE IS ALONG 50W S OF 15N MOVING W NEAR 20 KT.
CONVECTION IS THE VICINITY OF THE ITCZ WITH ISOLATED MODERATE
CONVECTION FROM 8N-11N BETWEEN 46W-53W.

TROPICAL WAVE...REMNANTS OF T.S. EARL...IS OVER THE WESTERN
CARIBBEAN ALONG 83W S OF 20N MOVING W 25 KT.  ASSOCIATED
CONVECTION HAS INCREASED BUT REMAINS UNORGANIZED.  SCATTERED
MODERATE TO STRONG CONVECTION IS INLAND OVER HONDURAS...AND
NICARAGUA FROM 11N-16N BETWEEN 84W-86W.  SCATTERED MODERATE
CONVECTION IS ALONG THE COAST FROM 14N-16N BETWEEN 82W-84W.

...ITCZ...
ITCZ AXIS IS ALONG 13N10W 6N20W 10N30W 9N35W 5N60W 9N70W.
ISOLATED MODERATE CONVECTION IS LOCATED ALONG THE COAST OF W
AFRICA FROM 7N-13N BETWEEN 12W-15W.

...DISCUSSION...
GULF OF MEXICO...
1021 MB HIGH IS OVER LOUISIANA NEAR 32N92W.  A REMNANT FRONTAL
TROUGH IS OVER THE N GULF OF MEXICO FROM THE FLORIDA PANHANDLE
TO S TEXAS ALONG 30N86W 26N97W.  ISOLATED MODERATE CONVECTION IS
WITHIN 30 NM OF THE TROUGH.  AIRMASS THUNDERSTORMS ARE NOTED
OVER INLAND FLORIDA FROM 25N-31N BETWEEN 80W-82W.  IN THE UPPER
LEVELS...A MID/UPPER LEVEL RIDGE DOMINATES MOST OF THE GULF OF
MEXICO. THE NEARLY STATIONARY RIDGE WILL KEEP UPSTREAM
DISTURBANCES N OF THE AREA WITH A SERIES OF SHORTWAVE TROUGHS
BYPASSING THE AREA OVER THE CENTRAL AND E UNITED STATES. THE
AIRMASS N OF THE BOUNDARY IS STILL FAIRLY DRY.

CARIBBEAN SEA...
THE PRIMARY WEATHER MAKER OVER THE CARIBBEAN IS THE REMNANTS OF
T.S. EARL WHICH DEGENERATED INTO A TROPICAL WAVE ON MONDAY. THE
WAVE CONTINUES TO PRODUCE STRONG GUSTY WINDS AND STRONG
CONVECTION. SEE ABOVE.  IN THE UPPER LEVELS... A SMALL CYCLONIC
CIRCULATION IS OVER THE NW CARIBBEAN SEA NEAR 20N85W.  CYCLONIC
FLOW IS WITHIN 240 NM OF THE CENTER.  OVER THE E CARIBBEAN...
SUBSIDENCE AND VERY DRY MIDDLE TO UPPER LEVEL AIR HAS MOVED INTO
THE AREA FROM THE ATLC AND IS SUPPRESSING CONVECTIVE ACTIVITY E
OF 70W. THIS DRY AIRMASS WILL MARCH WESTWARD ACROSS THE
CARIBBEAN LIMITING CONVECTION UNTIL THE NEXT WAVE APPROACHES
WED.

SUBTROPICAL ATLANTIC...
WEAK SURFACE TROUGH IS OVER THE W ATLANTIC ALONG 30N72W 28N79W.
1023 MB HIGH IS OVER THE CENTRAL ATLANTIC NEAR 35N51W.  A RIDGE
AXIS EXTENDS SW TO 30N70W.  SEE ABOVE FOR HURRICANE DANIELLE.
IN THE UPPER LEVELS... A SHORTWAVE RIDGE-TROUGH PATTERN PREVAILS
OVER THE W ATLC WITH A MID-UPPER LEVEL RIDGE EXTENDING FROM THE
N BAHAMAS NEWD TO BEYOND 32N70W AND A MID-UPPER LEVEL TROUGH
EXTENDING FROM BERMUDA SWD OVER HISPANIOLA NEAR 18N70W. FURTHER
E...MID-OCEANIC TROUGH HAS SPLIT FORMING A LARGE MID-UPPER LEVEL
LOW OVER THE CENTRAL ATLC NEAR 31N49W. THERE IS JUST ENOUGH
INSTABILITY ASSOCIATED WITH THE COLD CORE LOW TO PRODUCE AN AREA
OF SCATTERED SHOWERS/ISOLATED MODERATE CONVECTION FROM 26N-32N
BETWEEN 45W-50W.  HOWEVER...THE FLOW BECOME CONFLUENT S OF THE
UPPER LOW PRODUCING STRONG SUBSIDENCE S OF 24N BETWEEN 40-60W.
OVER THE E ATLC...HURRICANE DANIELLE CONTINUES TO LIFT NWD
AROUND THE W PERIPHERY OF A MID-UPPER LEVEL RIDGE ALONG 34N E OF
43W.  THE HURRICANE IS NOW ENCOUNTERING AN INCREASINGLY HOSTILE
ENVIRONMENT AND SHOULD WEAKEN OVER THE NEXT FEW DAYS.

TROPICAL ATLANTIC...
STRONG SUBSIDENCE OVER THE CENTRAL ATLC W OF HURRICANE DANIELLE
EXTENDS WELL INTO THE TROPICAL ATLC PRODUCING VERY DRY AIR AND
GENERALLY TRANQUIL WEATHER N OF THE ITCZ.  FURTHER E...E/W
ORIENTED MID-UPPER LEVEL RIDGE POSITIONED JUST N OF THE CAPE
VERDE ISLANDS IS PRODUCING DEEP ELY FLOW E OF HURRICANE
DANIELLE.  THIS REGIME IS GENERALLY FAVORABLE FOR ITCZ/WAVE
RELATED CONVECTION BUT NEITHER ARE CURRENTLY PRODUCING
SIGNIFICANT ACTIVITY.

$$
FORMOSA


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