[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 021210
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN SEP 2 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...SPECIAL FEATURES...

FELIX STRENGTHENS TO A CATEGORY TWO HURRICANE AS ITS CENTER
PASSES JUST NORTH OF BONAIRE. AT 02/1200 UTC IT WAS CENTERED
NEAR 13.0N 69.3W MOVING WEST AT 16 KT. AN AIR FORCE
RECONNAISSANCE AIRCRAFT MEASURED A CENTRAL PRESSURE OF 984 MB
DURING THE LAST EYE PENETRATION. MAXIMUM SUSTAINED WINDS ARE 85
KT WITH GUSTS TO 105 KT. FELIX CONTINUES ON A PATH JUST NORTH OF
DUE WEST OR 275/16...WITH STEERING PROVIDED BY A STRONG
DEEP-LAYER RIDGE OVER THE WESTERN ATLANTIC. THIS RIDGE IS
FORECAST BY THE COMPUTER MODELS TO BUILD WESTWARD...PREVENTING
FELIX FROM GAINING ANY SIGNIFICANT LATITUDE DURING THE NEXT FEW
DAYS. 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 INCLUDING THE LATEST WATCH AND WARNING
INFORMATION. NUMEROUS MODERATE TO STRONG CONVECTION IS WITHIN
100 NM OF CENTER. THE EYE OF FELIX IS WELL DEFINED IN THE DUTCH
ANTILLES RADAR. BONAIRE HAS BEEN REPORTED SUSTAINED WINDS OF
NEAR 20 KT AND HEAVY SHOWERS AT TIMES.

AN AREA OF LOW PRESSURE IS ASSOCIATED WITH A TROPICAL WAVE ALONG
38W...OR ABOUT MIDWAY BETWEEN AFRICA AND THE LESSER ANTILLES.
THE LOW HAS BEEN MOVING SLOWLY SOUTHWESTWARD OVERNIGHT BUT IS
FORECAST TO BEGIN MOVING WESTWARD LATER TODAY.  ASSOCIATED
SHOWER ACTIVITY IS LIMITED AND ENVIRONMENTAL CONDITIONS ARE ONLY
MARGINALLY FAVORABLE FOR DEVELOPMENT. HOWEVER...THE CIRCULATION
IS WELL-DEFINED AND THERE IS STILL SOME POTENTIAL FOR THIS
SYSTEM TO BECOME A TROPICAL DEPRESSION DURING THE NEXT COUPLE OF
DAYS. SCATTERED MODERATE CONVECTION IS FROM 11N-14N BETWEEN
38W-43W...DISPLACED TO THE W OF THE EXPOSED CENTER DUE TO ABOUT
20 KT OF ELY SHEAR.

...TROPICAL WAVES...

A TROPICAL WAVE IS INTRODUCED ALONG 20W S OF 18N ON THE 0600 UTC
SURFACE MAP. SATELLITE IMAGERY SHOWS A BROAD AREA OF CYCLONIC
TURNING ALONG THE WAVE AXIS NEAR 13N. 850 MB MODEL GUIDANCE AS
WELL AS THE CIMSS VORTICITY PRODUCT DEPICT A VORTICITY MAXIMUM
IN THIS AREA. THE VERTICAL SOUNDING FROM DAKAR SHOWED THE
PASSAGE OF THE WAVE WITH SE WINDS AT LOW LEVELS. A SFC LOW COULD
BE ADDED ALONG THE WAVE AXIS THIS MORNING AS THE VIS IMAGERY
COMES IN. SCATTERED MODERATE CONVECTION IS MOVING OUT OF THE
AFRICAN COAST BETWEEN 15N-20N...WHILE A BAND OF SIMILAR
CONVECTION IS ALONG 11N BETWEEN 21W-29W.

THE CARIBBEAN TROPICAL WAVE REMAINS ALONG 81W WHERE SATELLITE
IMAGERY SHOWS A CLASSIC INVERTED-V PATTERN IN THE CLOUD FIELD.
SCATTERED SHOWERS AND TSTMS ARE WITHIN 80 NM EITHER SIDE OF
AXIS. THE NORTHERN END OF THE WAVE IS OVER THE CAYMAN ISLANDS.
A DIFFLUENT PATTERN ALOFT...E OF AN UPPER TROUGH MOVING ACROSS
THE WRN CARIBBEAN IS SUPPORTING THIS ACTIVITY.

TROPICAL WAVE IS ALONG THE GUATEMALA/MEXICO BORDER ALONG 91W S
OF 20N MOVING W 10-15 KT. THIS WAVE...COUPLED WITH UPPER
DIFFLUENCE ASSOCIATED WITH AN UPPER HIGH OVER CENTRAL MEXICO IS
GENERATING SCATTERED MODERATE CONVECTION OVER THE BAY OF
CAMPECHE AND THE GULF OF TEHUANTEPEC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N17W 10N30W 11N35W 8N50W 11N21W.
BESIDES FOR THE CONVECTION ASSOCIATED WITH THE TROPICAL
WAVES...SCATTERED SHOWERS AND TSTMS ARE MAINLY S OF THE AXIS
FROM 7N-9N BETWEEN 22W-40W...AND WITHIN ABOUT 100 NM N OF AXIS
BETWEEN 22W-28W.

DISCUSSION...

GULF OF MEXICO...
A FAIRLY WEAK SFC PRES PATTERN CONTINUES TO DOMINATE THE GULF
EARLY THIS MORNING RESULTING IN LIGHT WINDS/LOW SEAS ACROSS THE
BASIN. A WEAK SFC TROUGH REMAINS OVER THE FAR WEST GULF
PRODUCING SCATTERED SHOWERS AND ISOLATED TSTMS WEST OF 92W BUT
PARTICULARLY JUST SOUTH OF BROWNSVILLE TEXAS. THIS ACTIVITY IS
BEING SUPPORTED BY VERY DIFFLUENT FLOW ALOFT BETWEEN RIDGING
OVER THE WESTERN GULF/CENTRAL MEXICO AND THE UPPER TROUGH
EXTENDING S THROUGH W/CENTRAL TEXAS. A STATIONARY FRONT REMAINS
ALONG THE NRN GULF COAST WITH A 1014 MB SFC LOW ALONG THE FRONT
NEAR 30N85W. A MOSAIC RADAR LOOP OVER THE SE U.S. SHOWS A LINE
OF SHOWER AND ISOLATED TSTM ASSOCIATED WITH THE FRONT OVER THE
NORTHERN GULF WATERS AS WELL AS SOME CONVECTIVE ACTIVITY OVER
THE NW CORNER OF THE GULF...THE MID/LOWER TEXAS COAST...AND JUST
OFF THE SE U.S. NEAR THE GEORGIA/SOUTH CAROLINA BORDER. 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 COUPLE OF DAYS. THE STATIONARY FRONT
WILL GRADUALLY DISSIPATE TODAY.

CARIBBEAN SEA...
HURRICANE FELIX REMAINS THE MAIN FEATURE OF INTEREST ACROSS THE
CARIBBEAN SEA. CURRENTLY...WATCHES AND WARNINGS ARE IN EFFECT
FOR THE ABC ISLANDS AND JAMAICA. INTERESTS ELSEWHERE IN THE
CENTRAL AND WESTERN CARIBBEAN SEA SHOULD CLOSELY MONITOR THE
PROGRESS OF THIS SYSTEM. FELIX IS EXPECTED TO PRODUCE RAINFALL
AMOUNTS OF 2 TO 4 INCHES...WITH POSSIBLE MAXIMUM ISOLATED
AMOUNTS OF 6 INCHES...OVER THE OFFSHORE ISLANDS OF VENEZUELA AND
THE NETHERLANDS ANTILLES ISLANDS OF ARUBA...BONAIRE...AND
CURACAO. FOR MORE DETAILS ON FELIX REFER TO THE SPECIAL FEATURE
SECTION ABOVE. A TROPICAL WAVE REMAINS FAIRLY ACTIVE ALONG 81W.
SEE ABOVE. ELSEWHERE...OUTER RAINBANDS OF FELIX ARE REACHING THE
CARIBBEAN COASTAL WATERS OF PUERTO RICO. MID TO UPPER RIDGING N
OF FELIX IS EXPECTED TO EXPAND W STEERING FELIX TO THE W OR WNW
OVER THE NEXT COUPLE OF DAYS ACROSS THE CARIB SEA. AN INVERTED
TROUGH IS OVER THE WESTERN CARIBBEAN.

ATLANTIC OCEAN...
A STATIONARY FRONT IS OVER N FLORIDA AND SE GEORGIA GENERATING
SCATTERED SHOWERS AND TSTMS. A WEAK SFC TROUGH ENTERS THE
FORECAST AREA NEAR 32N61W THEN CONTINUES TO 28M68W. WIDELY
SCATTERED MODERATE CONVECTION IS WITHIN 150 NM AHEAD OF THE
TROUGH. A WEAK SFC RIDGE ANCHORED ON A 1022 MB HIGH CENTERED
NEAR 31N44W DOMINATES THE REMAINDER OF THE BASIN PRODUCING
MOSTLY LIGHT TO MODERATE TRADES ACROSS THE AREA E OF 55W. LIGHT
WINDS ARE ALSO FOUND OVER MOST OF THE REGION W OF 55W AROUND A
RIDGE AXIS GENERALLY ALONG 26N...EXCEPT SLIGHTLY STRONGER ELY
WINDS CLOSER TO THE CARIBBEAN S OF 22N BETWEEN 60W-73W IN
RESPONSE TO THE GRADIENT N OF FELIX. ALOFT...AN UPPER
HIGH/TROUGH/HIGH PATTERN DOMINATES THE DISCUSSION AREA. AN UPPER
HIGH IS NEAR 26N67W COVERING THE WESTERN ATLC. AN UPPER LOW IS
NEAR 26N53W. THE REMAINDER OF THE AREA IS RELATIVELY QUIET
DOMINATED BY A STRONG MID TO UPPER HIGH CENTERED NEAR 23N30W.
STRONG E TO SE FLOW ON THE SW SIDE OF THIS HIGH IS SHEARING THE
LARGE TROPICAL WAVE AND AREA OF LOW PRES IN THE E ATLC.

$$
GR



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