[Tropical] Tropical Weather Discussion

[Nashville EMWIN]

AXNT20 KNHC 171042
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURES...

HURRICANE DANIELLE IS CENTERED NEAR 22.3N 39.9W AT 17/0900 UTC
MOVING NORTH NORTHWEST AT 15 KT.  MAXIMUM SUSTAINED WIND SPEED
IS 90 KT WITH GUSTS TO 110 KT AND THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 970 MB.  SEE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.  EVEN
THOUGH AN INTERMITTENT RAGGED EYE REMAINS EVIDENT IN IR
SATELLITE IMAGERY...DANIELLE APPEARS TO BE EXPERIENCING SOME 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 WITHIN 75 NM OF THE
CENTER OVER THE SW...SE...AND NE QUADRANTS.  NUMEROUS MODERATE
CONVECTION IS WITHIN 150 NM OVER THE NW QUADRANT.

...TROPICAL WAVES...

TROPICAL WAVE JUST W OF THE CAPE VERDE ISLANDS ALONG 27W S OF
16N MOVING W NEAR 20 KT. LATEST IR SATELLITE IMAGERY CONTINUES
TO SHOW A LOWER TO MID-LEVEL CIRCULATION NEAR 10N BUT CONVECTION
IS SPARSE.  ONLY A SMALL AREA OF ISOLATED MODERATE ACTIVITY IS
NOTED FROM 6N-11N BETWEEN 24W-30W.

TROPICAL WAVE APPROXIMATELY 750 NM E OF BARBADOS ALONG 46W S OF
15N MOVING W NEAR 20 KT. ITCZ CONVECTION IN THE VICINITY OF THE
WAVE HAS INCREASED OVERNIGHT WITH SCATTERED MODERATE ACTIVITY
FROM 7N-10N BETWEEN 42W-50W.

TROPICAL WAVE...REMNANTS OF T.S. EARL...IS OVER THE CENTRAL
CARIBBEAN ALONG 77W/78W S OF 18N MOVING W 25 KT.  EARLIER
QUIKSCAT DATA AND A NEARBY SHIP OBSERVATION AT 0000 UTC INDICATE
THAT THE WAVE CONTINUES TO PRODUCE STRONG WINDS TO NEAR GALE
FORCE PRIMARILY E OF THE AXIS FROM 14N-18N.  ASSOCIATED
CONVECTION HAS INCREASED OVERNIGHT BUT REMAINS UNORGANIZED.
SCATTERED STRONG CONVECTION FROM 13N-16N BETWEEN 77W-80W WITH
WIDELY SCATTERED SHOWERS/ISOLATED MODERATE CONVECTION FROM
16N-20N BETWEEN 73W-78W. THIS ACTIVITY IS CURRENTLY AFFECTING W
PORTIONS OF HISPANIOLA...E PORTIONS OF CUBA...AND JAMAICA.
GIVEN THE LACK OF ORGANIZATION AND THE RATHER FAST MOTION OF
THIS WAVE...SIGNIFICANT RAINFALL AMOUNTS ARE LESS LIKELY.
HOWEVER...GUSTY WINDS IN PASSING SHOWERS/TSTMS WILL AFFECT
JAMAICA TODAY AND THE CAYMAN ISLAND TONIGHT.

TROPICAL WAVE OVER GUATEMALA ALONG 89W/90W S OF 17N MOVING W
20-25 KT.  THE SATELLITE SIGNATURE ASSOCIATED WITH THIS WAVE IS
CURRENTLY POOR AND THE POSITION IS BASED PRIMARILY ON
EXTRAPOLATION. SMALL AREA OF SCATTERED MODERATE CONVECTION ALONG
THE N COAST OF HONDURAS.

...ITCZ...
ITCZ AXIS IS ALONG 10N10W 8N20W 10N30W 12N35W 5N60W 8N75W.
WIDELY SCATTERED MODERATE CONVECTION WITHIN 30 NM EITHER SIDE OF
AXIS FROM 30W-40W. SCATTERED MODERATE CONVECTION WITHIN 60 NM
EITHER SIDE OF AXIS W OF 40W.

...DISCUSSION...
GULF OF MEXICO...
A MID/UPPER LEVEL RIDGE...FROM S FLORIDA TO THE BAY OF
CAMPECHE...WILL REMAIN IN CONTROL OVER MOST OF THE GLFMEX
THROUGH MID-WEEK. 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.  DEEP
CONVECTION CONTINUES TO BE SPARSE WITH THE ONLY ACTIVITY OF NOTE
BEING A LINE OF WESTWARD MOVING SHOWERS/THUNDERSTORMS OVER THE
BAY OF CAMPECHE. ISOLATED SHOWERS/THUNDERSTORMS ARE NOTED ALONG
A REMNANT FRONTAL BOUNDARY EXTENDING FROM THE FLORIDA PANHANDLE
TO THE S TIP OF TEXAS. THE AIRMASS N OF THE BOUNDARY IS STILL
FAIRLY DRY SUPPRESSING CONVECTION ALONG THE N GULF COAST.
ELSEWHERE...A SECOND TROUGH OVER THE W ATLC EXTENDS ACROSS S
FLORIDA INTO THE SE GLFMEX.  ISOLATED SHOWERS/THUNDERSTORMS ARE
LOCATED JUST W OF THE FLORIDA KEYS.

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 WIDELY
SCATTERED SHOWERS/THUNDERSTORMS AS IT MARCHES RAPIDLY WESTWARD
AT 25 KT. A SECOND TROPICAL WAVE OVER GUATEMALA IS PRODUCING A
SMALL AREA OF CONVECTION ALONG THE N COAST OF HONDURAS WHILE THE
TYPICAL LOW LEVEL CONVERGENCE LINE FROM E PANAMA TO CENTRAL
NICARAGUA IS BECOMING MORE CONVECTIVE. 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...
A SHORTWAVE RIDGE-TROUGH PATTERN PREVAILS OVER THE W ATLC WITH A
MID-UPPER LEVEL RIDGE EXTENDING FROM THE N BAHAMAS NEWD TO
BEYOND 33N73W AND A MID-UPPER LEVEL TROUGH EXTENDING FROM
BERMUDA SWD OVER THE S BAHAMAS. FURTHER E...MID-OCEANIC TROUGH
HAS SPLIT FORMING A LARGE MID-UPPER LEVEL LOW OVER THE CENTRAL
ATLC NEAR 30N46W MOVING WNW 15 KT. THERE IS JUST ENOUGH
INSTABILITY ASSOCIATED WITH THE COLD CORE LOW TO PRODUCE AN AREA
OF SCATTERED SHOWERS/ISOLATED MODERATE CONVECTION FROM FROM
24N-32N BETWEEN 45W-60W.  HOWEVER...THE FLOW BECOME CONFLUENT S
OF THE UPPER LOW PRODUCING STRONG SUBSIDENCE S OF 25N BETWEEN
40-65W. OVER THE E ATLC...HURRICANE DANIELLE CONTINUES TO LIFT
NWD AROUND THE W PERIPHERY OF A MID-UPPER LEVEL RIDGE ALONG 20N
E OF 40W.  THE HURRICANE IS NOW ENCOUNTERING AN INCREASINGLY
HOSTILE ENVIRONMENT AND SHOULD WEAKEN OVER THE NEXT FEW DAYS.
AT THE SURFACE...SUBTROPICAL RIDGE EXTENDS FROM A STATIONARY
1026 MB HIGH OVER THE CENTRAL ATLC NEAR 35N52W SW TO THE
BAHAMAS. THE RIDGE IS DISRUPTED OVER FLORIDA BY A WEAK LOW LEVEL
TROUGH EXTENDING FROM 31N73W TO FLORIDA NEAR LAKE OKEECHOBEE.

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.

$$
RHOME






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