[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 150004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN OCT 14 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2315 UTC.

...TROPICAL WAVES...
AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 26W/27W SOUTH OF 18N
MOVING WEST 10 TO 15 KT. THIS WAVE CONTINUES TO EXHIBIT A RATHER
CLASSIC APPEARANCE IN SATELLITE IMAGERY WITH AN INVERTED V
PATTERN AND CLEAR CYCLONIC TURNING NOTED IN THE LOW CLOUD FIELD.
SHOWER AND TSTM ACTIVITY REMAINS DISORGANIZED WITH SW SHEAR OVER
THE AREA N OF 10N. THE MOST CONCENTRATED AREA OF SCATTERED TSTM
ACTIVITY IS WITHIN 90NM EITHER SIDE OF THE AXIS N OF 13N.
SCATTERED SHOWERS AND TSTMS ARE ELSEWHERE WITHIN 250NM EITHER
SIDE OF THE AXIS S OF 10N.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 46W SOUTH OF 16N MOVING
WEST 10 TO 15 KT. WHILE NOT AS WELL DEFINED AS THE WAVE FURTHER
E...A LOW AMPLITUDE CYCLONIC SWIRL REMAINS EVIDENT FROM 9N-14N
WITHIN 120NM EITHER SIDE OF THE AXIS. SCATTERED SHOWERS AND
TSTMS ARE WITHIN 90 NM EITHER SIDE OF THE AXIS FROM
10N-12N...WITH MINIMAL ACTIVITY NOTED ELSEWHERE NEAR THE WAVE.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 77W...WITH A 1006 MB LOW
PRESSURE CENTER ALONG IT NEAR 13N MOVING W NEAR 10 KT. THE
CIRCULATION ASSOCIATED WITH THE LOW IS FAIRLY WELL
DEFINED...THOUGH THE SURROUNDING SHOWER AND TSTM ACTIVITY
REMAINS DISORGANIZED. SCATTERED MODERATE TO STRONG CONVECTION IS
DISPLACED WITHIN 250 NM W OF THE AXIS FROM 11N-17N...DUE TO
STRONG E/NE SHEAR OVER THE AREA. THIS ACTIVITY IS APPROACHING
THE COAST OF NICARAGUA. THIS SYSTEM IS EXPECTED TO CONTINUE
MOVING WESTWARD WITHOUT SIGNIFICANT DEVELOPMENT DUE TO THE
STRONG UPPER-LEVEL WINDS.

...THE ITCZ...
AXIS CENTERED ALONG 6N11W 7N25W 8N44W 11N56W 10N63W. BESIDES FOR
THE ACTIVITY ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED
MODERATE CONVECTION IS WITHIN 90 NM S OF THE AXIS BETWEEN
13W-21W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE ALSO AFFECTING
THE WATERS NEAR TRINIDAD AND NE VENEZUELA FROM 7N-12N W OF 58W.

DISCUSSION...

THE GULF OF MEXICO...
THE GULF REMAINS TRANQUIL OVERALL THIS EVENING WITH DEEP
CONVECTION AT A MINIMUM DUE TO A PERSISTENT MID TO UPPER LEVEL
CAP. WV IMAGERY SHOWS VERY DRY/STABLE AIR OVER THE ENTIRE GULF
EXCEPT FOR THE FAR SE PORTION AND NEAR THE YUCATAN CHANNEL. THE
SFC TROUGHING EXTENDING N FROM THE LOW IN THE NW CARIBBEAN IS
GENERATING SCATTERED SHOWERS/ISOLATED TSTMS BETWEEN THE NRN
YUCATAN PENINSULA AND THE FLORIDA KEYS. OTHER MOSTLY
SHALLOW...SCATTERED SHOWER ACTIVITY NOTED IN LOW LEVEL CONFLUENT
FLOW WITHIN 30NM OF THE LINE FROM THE BAY OF CAMPECHE AT 18N93W
TO CORPUS CHRISTI. SIMILAR ACTIVITY NOTED ABOUT 150NM S OF
MOBILE. THE LARGE SCALE SFC PATTERN REMAINS DOMINATED BY THE SRN
PORTION OF HIGH PRES OVER THE OHIO RIVER VALLEY. THE INTERACTION
BETWEEN THE HIGH AND THE LOW PRES OVER THE NW CARIB IS PRODUCING
MODERATE NE TO E WINDS FOR THE ERN GULF THAT BEND MORE SE IN THE
WRN PORTION. SCATTERED SHOWER ACTIVITY EXPECTED TO SPREAD NW
INTO THE MIDDLE GULF FROM THE CARIBBEAN OVER THE NEXT DAY OR SO.

THE CARIBBEAN SEA...
A PERSISTENT SFC LOW REMAINS JUST OFF THE YUCATAN
PENINSULA...ANALYZED 1007 MB NEAR 18N86W AT 1800 UTC. THIS IS
SPREADING SCATTERED SHOWERS AND TSTMS INLAND AND OVER THE GULF
OF HONDURAS FROM 15N-21N MAINLY W OF 85W. THIS SYSTEM IS
EXPECTED TO MOVE OVER THE YUCATAN PENINSULA TONIGHT AND TOMORROW
WITH LITTLE DEVELOPMENT. HOWEVER...LOCALLY HEAVY RAINS ARE STILL
POSSIBLE OVER PORTIONS OF CENTRAL AMERICA AND SOUTHEASTERN
MEXICO TONIGHT AND TOMORROW. ANOTHER SFC LOW IS NEAR 13N77W
ASSOCIATED WITH A TROPICAL WAVE...AND IS SPREADING SHOWERS AND
TSTMS WWD TOWARDS NICARAGUA. SEE TROPICAL WAVE SECTION ABOVE FOR
DETAILS. AN UPPER-LEVEL LOW IS LOCATED NEAR THE ABC
ISLANDS...AND IS SUPPORTING ISOLATED TSTMS FROM 12N-18N BETWEEN
66W-71W. A FAIRLY SIGNIFICANT PLUME OF MOISTURE WITH ADDITIONAL
SHOWER ACTIVITY IS IN THE UPPER DIFFLUENT ZONE TO THE E OF THE
UPPER LOW...AFFECTING THE SE CARIBBEAN...TRINIDAD...NE
VENEZUELA...AND THE WINDWARD ISLANDS. BASED ON SOME OF THE
RECENT RAOB DATA FROM THIS AREA...THERE MAY ALSO BE A LOW
AMPLITUDE TROPICAL WAVE OR SFC TROUGH IN THE VICINITY SUPPORTING
THE WEATHER OVER THE SE CARIBBEAN. HOWEVER...I CURRENTLY HAVE
LOW CONFIDENCE IN THIS SO WILL PROBABLY HOLD OFF ON ADDING
ANOTHER WAVE TO THE 15/0000 UTC MAP AT THIS POINT.

THE ATLANTIC OCEAN...
A SLOW MOVING FRONTAL BOUNDARY ENTERS THE REGION NEAR 32N59W AND
EXTENDS SW TOWARD THE CENTRAL BAHAMAS AND STRAITS OF FLORIDA TO
24N79W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE GENERALLY
WITHIN 120 NM OF THE BOUNDARY. DIFFLUENT FLOW ALOFT BETWEEN
TROUGHING JUST OFF THE EAST COAST AND AN UPPER HIGH NEAR 27N56W
IS ALSO SUPPORTING THIS ACTIVITY. THE COMBINATION OF LOW-LEVEL
CONVERGENCE AND A PLENTIFUL AMOUNT OF UPPER MOISTURE...ADVECTED
BY STRONG SWLY FLOW...IS PRODUCING ABUNDANT CLOUDINESS ELSEWHERE
BETWEEN THE SE BAHAMAS AND BERMUDA. THE TIGHTENED PRES GRADIENT
BETWEEN THE FRONT...LOW PRES IN THE CARIB AND HIGH PRES OVER THE
OHIO RIVER VALLEY IS PRODUCING MODERATE TO FRESH NE-E WINDS
ACROSS PORTIONS OF THE SW NORTH ATLC...NW BAHAMAS AND S
FLORIDA. THESE WINDS GENERALLY EXPECTED TO PERSIST THROUGH MON.

CONDITIONS ARE FAIRLY TRANQUIL ACROSS MUCH OF THE REMAINDER OF
THE CENTRAL AND E ATLC. THE SFC PATTERN IS CONTROLLED BY RIDGING
EXTENDING S/SW FROM A 1023 MB HIGH SITUATED OVER THE AZORES NEAR
39N28W. THIS IS PRODUCING MOSTLY LIGHT WINDS OVER THE
SUBTROPICAL E AND CENTRAL ATLC...WHILE MODERATE TRADES PERSIST
IN THE TROPICS. THE UPPER PATTERN OVER THE E ATLC CONSISTS OF A
LARGE SCALE UPPER TROUGH. A SWLY JET BRANCH ORIGINATES JUST
AHEAD OF THE BASE OF THE TROUGH OVER THE TROPICAL ATLC AND
EXTENDS NE TO AFRICA NEAR 22N17W. THIS JET IS SHEARING THE
TROPICAL WAVES ALONG 27W AND 46W AND SPREADING HIGH LEVEL
CLOUDINESS ACROSS THE TROPICAL E ATLC.

$$
WILLIS


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