[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 011753
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT SEP 1 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1730 UTC.

...SPECIAL FEATURE...

TROPICAL STORM FELIX IS CENTERED NEAR 12.5N 64.5W AT 01/1800 UTC
OR ABOUT 365 NM SSE OF SAN JUAN PUERTO RICO AND ABOUT 465 NM SE
OF SANTO DOMINGO IN THE DOMINICAN REPUBLIC MOVING W NEAR 16 KT.
THE LATEST MINIMUM CENTRAL PRESSURE REPORTED BY AN AIR FORCE
RESERVE HURRICANE HUNTER PLANE WAS 999 MB. MAXIMUM SUSTAINED
WIND SPEED HAS INCREASED TO 60 KT WITH GUSTS TO 75 KT...THIS
MEANS THAT FELIX IS VERY CLOSE TO HURRICANE INTENSITY. FELIX IS
ON A STRENGTHENING TREND WITH THE CIRCULATION APPEARING TIGHTER
AND SPIRAL RAIN BANDS BECOMING BETTER DEFINED AS SEEN ON
SATELLITE AND THE MARTINIQUE RADAR. IR IMAGES ALSO SHOW A FAIRLY
TIGHT INNER CORE WITH NUMEROUS MODERATE/SCATTERED STRONG
CONVECTION WITHIN 45 NM OF THE CENTER. SCATTERED MODERATE
/ISOLATED STRONG CONVECTION IS ELSEWHERE WITHIN 180 NM OF THE
CENTER IN RAINBANDS. THIS CONVECTION EXPANDS FURTHER W...WITHIN
240 NM...IN THE SW QUADRANT WHERE THERE IS ENHANCED CONVERGENCE.
STEADY STRENGTHENING IS FORECAST OVER THE NEXT COUPLE OF DAYS AS
ATMOSPHERIC AND OCEANIC CONDITIONS ARE FAVORABLE ACROSS THE
CARIB SEA AND FELIX COULD BECOME A HURRICANE LATER TONIGHT OR
SUNDAY. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER
AWIPS/WMO HEADERS MIATCPAT1/WTNT31 KNHC AND THE FULL
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC
FOR MORE DETAILS.

...TROPICAL WAVES...

WELL DEFINED TROPICAL WAVE IS TILTED ALONG 19N34W 6N36W MOVING W
15 KT. A 1009 MB LOW SITS ALONG THIS WAVE AXIS NEAR 13N36W. VIS
IMAGES SHOW THE LOW-LEVEL CENTER EXPOSED TO THE E OF SCATTERED
MODERATE CONVECTION LOCATED WITHIN 300 NM TO THE W OF THE
CENTER. THIS WAVE IS OBVIOUSLY FEELING THE EFFECTS OF ELY SHEAR
PRODUCED BY A STRONG UPPER HIGH CENTERED TO THE N. FURTHER
DEVELOPMENT IS POSSIBLE AS THE SYSTEM MOVES W INTO A MORE
FAVORABLE ENVIRONMENT OVER THE NEXT DAY OR TWO. IT IS NOTABLE
THAT THIS WAVE IS PRODUCING A LARGE PERTURBATION IN THE ITCZ
ACROSS A RATHER LARGE AREA.

TROPICAL WAVE HAS BEEN ADJUSTED W ALONG 77W/78W S OF 20N MOVING
W 15 KT. THIS ADJUSTMENT WAS BASED MOSTLY ON THE PRESENTATION ON
SATELLITE WHICH SHOWS THE ASSOCIATED CLOUD MASS DEEPENING AND
EXPANDING FROM JAMAICA TOWARD THE N COAST OF COLOMBIA. SCATTERED
SHOWERS AND TSTMS ARE EMBEDDED WITHIN 120 NM OF THE AXIS...MOST
ORGANIZED FROM 15N-18N. RECENT VISIBLE IMAGES SHOWS A POSSIBLE
VAGUE INVERTED V-SHAPE TO THE CLOUDS SUGGESTING THAT THIS WAVE
COULD BE HIGHER AMPLITUDE. IN ADDITION...A CLUSTER OF SHOWERS
AND TSTMS HAVE DEVELOPED OVER THE WRN BAHAMAS APPROACHING
EXTREME S FLA...AT LEAST PARTIALLY RELATED TO THIS WAVE.

TROPICAL WAVE IS ALONG 87W S OF 21N MOVING W 10-15 KT. THIS WAVE
IS DIFFICULT TO LOCATE TODAY IN THE AVAILABLE DATA. LITTLE
SHOWER ACTIVITY IS IN THE VICINITY OF THIS ANALYZED FEATURE.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N16W 14N33W 9N38W 11N58W. BESIDES
FOR THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE...SCATTERED
SHOWERS AND ISOLATED TSTMS ARE WITHIN 360 NM S OF THE AXIS E OF
27W.

DISCUSSION...

GULF OF MEXICO...
VERY WEAK SFC PRES PATTERN ACROSS THE GULF TODAY CHARACTERIZED
BY A PAIR OF WEAK TROUGHS IN THE REGION. ONE TROUGH EXTENDS FROM
A 1012 MB LOW OVER THE FL PANHANDLE TO 28N88W. DOPPLER RADAR
DATA DEPICTS NARROW LINES OF SCATTERED SHOWERS AND TSTMS MAINLY
WITHIN 90 NM W OF THE TROUGH AXIS. THIS ACTIVITY WILL LIKELY
INCREASE AND EXPAND THIS AFTERNOON ESPECIALLY OVER N AND CENTRAL
FLORIDA WHEN LOCAL EFFECTS CONTRIBUTE. THE OTHER TROUGH RUNS N-S
NEAR THE COAST OF MEXICO ALONG 97W S OF 26N. THIS TROUGH IS MORE
ACTIVE...IN TERMS OF MOISTURE...WITH SCATTERED SHOWERS AND TSTMS
NOTED WITHIN 120 NM EITHER SIDE OF THE AXIS. ANOTHER AREA
EXPERIENCING SOMEWHAT ORGANIZED PRECIP IS THE NW GULF NEAR THE
TX AND WRN LA COAST N OF 27N W OF 93W. THIS WEATHER IS
ASSOCIATED WITH A STALLED FRONT DRAPED ACROSS THE U.S. GULF
COAST. THE REMAINDER OF THE AREA IS RELATIVELY TRANQUIL WITH
PATCHES OF ISOLATED SHOWERS AND LIGHT AND VARIABLE WINDS. MODELS
SUGGEST LITTLE CHANGE OVER THE NEXT 24 HOURS.

CARIBBEAN SEA...
ATTENTION REMAINS FOCUSED ON TROPICAL STORM FELIX MOVING ACROSS
THE SE CARIB. A PRECIP REPORT FROM TRINIDAD SHOWS 1.5 INCHES
FELL ON THE ISLAND YESTERDAY. ADDITIONAL RAINFALL OF 1-2 INCHES
IS EXPECTED ACROSS THE SRN WINDWARD ISLANDS WITH TOTAL
ACCUMULATIONS OF UP TO 7 IN. RAINFALL AMOUNTS OF 2-4 INCHES ARE
POSSIBLE OVER THE OFFSHORE ISLANDS OF VENEZUELA AND THE
NETHERLANDS ANTILLES ABC ISLANDS. FOR MORE DETAILS ON FELIX
REFER TO THE SPECIAL FEATURE SECTION ABOVE. A TROPICAL WAVE HAS
BECOME MORE ACTIVE S OF JAMAICA...REFER TO THAT SECTION ABOVE
FOR DETAILS. BESIDES FOR ALL OF THAT...THERE A COUPLE OF SHOWERS
OVER WRN CUBA AND A PORTION OF THE NW CARIB ASSOCIATED WITH
MOISTURE ROTATING AROUND AN UPPER TROUGH IN THE REGION. MID TO
UPPER RIDGING N OF FELIX IS EXPECTED TO EXPAND W STEERING FELIX
TO THE W OR WNW OVER THE NEXT FEW DAYS ACROSS THE CARIB SEA.

ATLANTIC OCEAN...
SCATTERED SHOWERS AND TSTMS EXIST N OF 29N BETWEEN 60W AND 68W.
THE LOW-LEVEL FEATURE HELPING TO TRIGGER THIS ACTIVITY IS A
PRE-FRONTAL TROUGH WHICH CURVES INTO OUR AREA ALONG 32N68W
30N74W. UPPER WLY FLOW AND DIFFLUENCE BETWEEN AN UPPER HIGH
CENTERED NEAR 28N68W AND AN UPPER LOW NEAR 29N53W IS ENHANCING
THIS MOISTURE PLUME AND SPREADING DEBRIS CLOUDINESS AND ISOLATED
SHOWERS FROM 23N-28N BETWEEN 50W-60W. A CLUSTER OF SHOWERS AND
TSTMS HAS RECENTLY DEVELOPED OVER THE WRN BAHAMAS APPROACHING S
FLA. THIS ACTIVITY APPEARS RELATED IN PART TO THE N EXTENSION OF
THE CARIB WAVE. THE REMAINDER OF THE AREA IS RELATIVELY QUIET
DOMINATED BY A STRONG MID TO UPPER HIGH CENTERED NEAR 23N30W.
STRONG ELY FLOW ON THE S SIDE OF THIS HIGH IS SHEARING THE LARGE
TROPICAL WAVE AND AREA OF LOW PRES IN THE E ATLC.

ELSEWHERE AT THE SFC...TYPICAL SUBTROPICAL RIDGING IS
INTERRUPTED A BIT BY THE AFOREMENTIONED TROUGHING IN THE W
ATLC...NEAR BERMUDA...AND A LARGE NEARLY STATIONARY LOW PRES
SYSTEM IN THE N CENTRAL ATLC. THIS HAS ALLOWED TRADES TO BE
MOSTLY LIGHT TO MODERATE ACROSS THE AREA...EXCEPT FOR IN THE
VICINITY OF TROPICAL STORM FELIX.

$$
CANGIALOSI


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