[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211753
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE AUG 21 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 1715 UTC.

...SPECIAL FEATURE...
THE CENTER OF NOW CATEGORY ONE HURRICANE DEAN AT 21/1800 UTC WAS
NEAR 19.2N 90.4W...OR ABOUT 45 MILES...75 KM...SOUTH-SOUTHEAST
OF CAMPECHE MEXICO. HURRICANE DEAN IS MOVING WEST NEAR 18 MPH.
THE MAXIMUM SUSTAINED WIND SPEEDS HAVE DIMINISHED TO NEAR 85 MPH
WITH HIGHER GUSTS. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 960
MB. PLEASE SEE THE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY UNDER
MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS INCLUDING THE LATEST
WATCH AND WARNING INFORMATION. DEAN HAS WEAKENED OVER THE
YUCATAN PENINSULA OVER THE LAST SEVERAL HOURS. HOWEVER...DEAN IS
ABOUT TO EMERGE INTO THE BAY OF CAMPECHE...AND WILL HAVE ABOUT
18 HOURS OVER WATER TO REGAIN STRENGTH. NUMEROUS MODERATE
CONVECTION IS OVER LAND AND THE ERN BAY OF CAMPECHE FROM 16N-20N
BETWEEN 89W-95W. SCATTERED MODERATE IS ELSEWHERE FROM 15N-26N
BETWEEN 86W-95W. OVER THE LAST FEW HOURS LIGHTNING DATA HAS BEEN
DEPICTING SEVERAL STRIKES IN THE BANDS NOTED IN THE GULF FROM
22N-26N BETWEEN 87W-94W.

...TROPICAL WAVES...
A TROPICAL WAVE HAS BEEN ADDED TO THE 21/1200 UTC MAP TILTED
ALONG 23N54W 15N52W 6N50W...ESTIMATED TO BE MOVING W NEAR 15-20
KT. THE WAVE WAS ADDED DUE ITS SIGNATURE IN THIS MORNINGS
VISIBLE SATELLITE IMAGERY SHOWING CYCLONIC TURNING IN THE LOW
LEVEL CLOUD FIELD...AND ALSO ITS APPEARANCE IN A LONG TERM LOOP
OVER THE LAST FEW DAYS. IN ADDITION...THE WAVE ALSO SHOWS UP
WELL IN THE UW-CIMSS SSMI/AMSRE DERIVED TPW PRODUCT AS A
SECONDARY SURGE OF MOISTURE BEHIND THE LARGER WAVE TO ITS W.
FINALLY...BOTH THE DAKAR AND SAL SOUNDINGS SHOWED TWO SEPARATE
WAVES PASS LAST WEEK. ASSOCIATED SCATTERED MODERATE CONVECTION
IS LIMITED TO WHERE THE SRN PORTION OF THE WAVE INTERSECTS WITH
THE ITCZ FROM 7N-12N BETWEEN 47W-55W.

A LARGE AMPLITUDE TROPICAL WAVE IS ALONG 67W S OF 29N MOVING W
15-20 KT. THE WAVE IS INTERACTING WITH AN ELONGATED UPPER LOW
MOVING W THROUGH HISPANIOLA TO PRODUCE DISORGANIZED SCATTERED
SHOWERS AND ISOLATED TSTMS...MAINLY FROM 20N-29N BETWEEN
58W-72W. A 1014 MB LOW IS ALONG THE WAVE AXIS NEAR 25N BUT THIS
CIRCULATION IS RATHER RAGGED AT THE MOMENT. UPPER-LEVEL WINDS
ARE BECOMING LESS FAVORABLE FOR DEVELOPMENT FOR THIS SYSTEM.

...THE ITCZ...
AXIS CENTERED ALONG 12N16W 11N30W 10N40W 11N48W 7N59W. SCATTERED
MODERATE CONVECTION IS ALONG AND OFF THE AFRICAN COAST FROM
6N-13N E OF 22W. SOME OF THIS APPEARS TO BE ASSOCIATED WITH A
TROPICAL WAVE STILL INLAND OVER AFRICA. SCATTERED MODERATE IS
ALSO WITHIN 30 NM N AND 210 NM S OF THE AXIS BETWEEN 33W-47W.

DISCUSSION...

THE GULF OF MEXICO...
HURRICANE DEAN WILL MOVE INTO THE FAR SRN GULF/ERN BAY OF
CAMPECHE OVER THE NEXT COUPLE OF HOURS. SEE DETAILS ABOVE. ASIDE
FROM THE HIGH WINDS/SEAS NEAR THE CENTER OF DEAN...A FAIRLY
SIGNIFICANT LONGER PERIOD SWELL WILL SPREAD THROUGH THE NW AND
MIDDLE GULF OVER THE NEXT COUPLE OF DAYS. SEE STATEMENTS FROM
LOCAL WEATHER SERVICE OFFICES AND TAFB HIGH SEAS/OFFSHORE WATERS
FORECASTS FOR MORE DETAILS. ELSEWHERE AT THE SFC A WEAK RIDGE IS
ALONG 30N AND WILL REMAIN QUASI-STATIONARY OVER THE NEXT FEW
DAYS. ALOFT...A MID TO UPPER LOW CONTINUES TO MOVE INLAND OVER
NRN MEXICO WHILE A MID TO UPPER RIDGE IS N/NE OF DEAN...STEERING
THE CYCLONE WWD.

THE CARIBBEAN SEA...
WINDS AND SEAS STILL AN ISSUE IN THE FAR NW PORTION FROM
DEAN...BUT WILL CONTINUE TO STEADILY RELAX THROUGH WED AS THE
STORM MOVES AWAY FROM THE AREA. OUTSIDE OF DEAN THE MOST ACTIVE
WEATHER IS IN THE SW PORTION...WITH SCATTERED SHOWERS/TSTMS S OF
16N BETWEEN 75W-84W. IN ADDITION TO CONFLUENT LOW LEVEL FLOW IN
THIS VICINITY...THE ACTIVITY IS BEING SUPPORTED BY DIFFLUENCE
ALOFT BETWEEN NE FLOW OVER THE SW CARIBBEAN AND THE FLOW AROUND
THE DOMINATING UPPER LOW MOVING W OVER HISPANIOLA. THE SW FLOW
AHEAD OF THIS LOW IS ADVECTING TROPICAL MOISTURE NE THROUGH THE
ERN CARIBBEAN. THIS ALONG WITH THE TROPICAL WAVE IN THE VICINITY
IS SUPPORTING SCATTERED SHOWERS MAINLY N OF 15N E OF 70W.

THE ATLANTIC OCEAN...
THE AREA JUST OFF THE FLORIDA/SE U.S. COAST IS EXPERIENCING FAIR
WEATHER WITH DEEP LAYER RIDGING AND DRY MID TO UPPER AIR IN
PLACE. THE WEATHER IS A BIT MORE ACTIVE FURTHER E/N OF
HISPANIOLA AND PUERTO RICO DUE TO THE COMBINATION OF THE UPPER
LOW AND TROPICAL WAVE IN THE VICINITY...SEE DETAILS ABOVE. AN
UPPER HIGH IS NEAR 31N64W WHILE A BENIGN UPPER LOW IS NEAR
32N34W. TYPICAL UPPER RIDGING EXTENDS W FROM AFRICA OUT TO 30W.
ELSEWHERE AT THE SFC LARGE SCALE RIDGING DOMINATES IN THE S/SW
PERIPHERY OF A 1024 MB HIGH CENTERED WELL NE OF THE AZORES. THIS
IS PRODUCING ABUNDANT FAIR WEATHER AND MODERATE TRADES N OF 15N
E OF 50W.

$$
WILLIS




This weather bulletin was brought to you by:
www.nashvilleweather.net