[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 071726
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT OCT 07 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
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...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...TROPICAL WAVES...
A FAIRLY HIGH AMPLITUDE TROPICAL WAVE IS ALONG 39W S OF 21N
MOVING W ABOUT 15 KT. THE WAVE AXIS IS EASILY IDENTIFIABLE ON
SATELLITE IMAGERY WITH A LARGE INVERTED-V SIGNATURE NOTED.
SCATTERED MODERATE CONVECTION IS EMBEDDED IN THE ITCZ WITHIN
SEVERAL HUNDRED NM OF THE WAVE AXIS...DISCUSSED IN THE ITCZ
SECTION. ONLY ISOLATED TO SCATTERED HIGHLY SHEARED SHOWERS ARE
WITHIN 180 NM E OF THE WAVE AXIS N OF 12N.

A TROPICAL WAVE IS ALONG 57W S OF 16N MOVING W NEAR 15 KT OVER
THE PAST 24 HOURS. THIS WAVE HAS LITTLE SIGNATURE ASSOCIATED
WITH IT. SOME SLIGHT LOW-MID LEVEL CYCLONIC TURNING IS LOCATED E
OF THE AXIS...HOWEVER NO ADJUSTMENT IN THE WAVE PSN WAS MADE DUE
TO LACK OF STRONG EVIDENCE IN SFC AND UPPER AIR OBS/MODEL DATA.
SCATTERED SHOWERS AND TSTMS ARE WITHIN 240 NM EITHER SIDE OF THE
WAVE AXIS.

A TROPICAL WAVE IS IN THE ERN CARIBBEAN ALONG 66W S OF 17N
MOVING W 10 TO 15 KT. LITTLE WAVE STRUCTURE IS NOTED ON VIS
IMAGES. WESTERLY UPPER LEVEL FLOW IS SHEARING SCATTERED SHOWERS
AND TSTMS TO THE WINDWARD ISLANDS...BUT EVEN THIS ACTIVITY HAS
BEEN DISSIPATING OVER THE LAST FEW HOURS.

A TROPICAL WAVE HAS EXITED THE CARIBBEAN SEA ALONG 89W S OF 19N
MOVING W 10 TO 15 KT. CLUSTERS OF SCATTERED MODERATE CONVECTION
ARE WITHIN 400 NM EITHER SIDE OF THE WAVE AXIS. THE MOST
IMPRESSIVE CLUSTER IS IN THE WRN CARIBBEAN SEA FROM 16N-20N
BETWEEN 83W-86W. THIS ACTIVITY IS BEING ENHANCED BY UPPER
DIFFLUENT FLOW BETWEEN A LARGE TROUGH IN THE GULF AND A RIDGE
IN THE SRN CARIBBEAN.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N15W 7N30W 9N38W 6N50W 7N57W.
BESIDES FOR THE CONVECTION DISCUSSED IN THE TROPICAL WAVES
SECTION...SCATTERED MODERATE IS WITHIN 120 NM EITHER SIDE OF THE
AXIS BETWEEN 30W AND 48W. SIMILAR CONVECTION LIES E OF 18W FROM
7N-11N.

...DISCUSSION...
THE GULF OF MEXICO...
THE MAIN FEATURE IN THE GULF IS A LARGE DEEP UPPER TROUGH THAT
COVERS MUCH OF THE CENTRAL AND EASTERN PORTION OF THE AREA. A
LARGE CUT OFF LOW HAS DEVELOPED OVER NORTH CAROLINA...EMBEDDED
IN THIS BROAD TROUGHING. STRONG SUBSIDENCE ACCOMPANIES THE
TROUGH WITH VERY DRY AIR ALOFT NOTED ON WATER VAPOR IMAGES E OF
90W N OF 24N. A NARROW SQUASHED RIDGE LIES TO THE W OF THE
TROUGH EXTENDING FROM THE YUCATAN PENINSULA NNW TO THE
MIDWESTERN STATES OF THE U.S. A FAIR AMOUNT OF MOISTURE IS IN
THE WRN GULF ASSOCIATED WITH THE MOIST SLY FLOW OF THE UPPER
RIDGE. THIS MOISTURE IS THEN ADVECTED EASTWARD ACROSS THE SRN
GULF AND NRN CARIBBEAN BY A WESTERLY JET WITH CORE WINDS NEAR 60
KT BASED ON CIMSS DERIVED UPPER LEVEL WINDS. A SFC TROUGH IS
EMBEDDED IN THE HIGH LEVEL MOISTURE IN THE WRN GULF ALONG 94W
FROM 20N-26N AND IS ENHANCING SCATTERED SHOWERS AND TSTMS WITHIN
90 NM EITHER SIDE OF THE AXIS. A WEAK COLD FRONT IS IN THE NRN
GULF STRETCHING FROM CENTRAL FLORIDA TO 27N94W. ONLY SLIGHTLY
DRIER AIR AND A FAINT NARROW BAND OF LOW CLOUDS REPRESENT THIS
BOUNDARY. GFS SHOWS THE DRY AIRMASS IN THE CENTRAL AND EASTERN
GULF TO REMAIN IN PLACE THRU TUE...WITH SOME INCREASE IN
MOISTURE IN THE WRN GULF.

THE CARIBBEAN SEA...
THE MOST ACTIVE WEATHER IN THE CARIBBEAN IS IN THE GULF OF
HONDURAS WHERE SCATTERED MODERATE CONVECTION EXISTS FROM 16N TO
20N BETWEEN 83W AND 86W. THIS ACTIVITY IS ASSOCIATED WITH A
TROPICAL WAVE ALONG 89W AND UPPER DIFFLUENT AIR S OF A
WESTERLY JET BETWEEN AN UPPER HIGH NEAR 15N80W AND A LARGE UPPER
TROUGH ACROSS THE CENTRAL/EASTERN GULF. THIS CONVECTION HAS
DECREASED IN INTENSITY SLIGHTLY OVER THE PAST FEW HOURS. SIMILAR
CONVECTION IS IN THE SW CARIBBEAN S OF 12N W OF 78W ASSOCIATED
WITH THE ITCZ. MUCH OF THE CENTRAL AND EASTERN CARIBBEAN IS
RATHER QUIET WITH A FAIR AMOUNT OF MODERATELY DRY AIR AND
WESTERLY UPPER LEVEL FLOW IN PLACE...EXCEPT FOR SCATTERED
SHOWERS AND TSTMS IN THE WINDWARD ISLANDS ASSOCIATED WITH A
SHEARED TROPICAL WAVE. MODERATE TO STRONG ELY TRADE WINDS ARE
BLOWING ACROSS THE CARIBBEAN WITH THE STRONGEST WINDS OF 20-25
KT OVER THE SOUTH CENTRAL CARIBBEAN. LITTLE CHANGE IN THESE
WINDS ARE EXPECTED OVER THE NEXT 24 HOURS.

THE ATLANTIC OCEAN...
A LARGE UPPER LEVEL TROUGH COVERS MUCH OF THE EASTERN U.S. AND
WRN ATLC W OF 70W N OF 24N. MODERATE TO STRONG SUBSIDENCE IS
ASSOCIATED WITH THE TROUGH. A WEAK 1018 MB SFC HIGH IS LOCATED
UNDERNEATH THE TROUGH NEAR 28N74W. A MID-UPPER LEVEL SUBTROPICAL
RIDGE LIES TO THE E OF THE TROUGH AND COVERS THE REGION BETWEEN
38W AND 63W. DRY STABLE AIR IS ALSO IN PLACE UNDERNEATH THE
RIDGE LIMITING ANY SHOWER ACTIVITY. A SWLY JET EXISTS BETWEEN
THESE FEATURES AND IS ADVECTING A SWATH OF MOISTURE BETWEEN 63W
AND 70W. A 1008 MB SFC LOW IS LOCATED NEAR 34N67W WITH A SFC
TROUGH EXTENDING SWD FROM THE LOW TO THE ERN BAHAMAS. THIS LOW
WAS BEING MONITORED OVER THE LAST DAY OR TWO FOR POSSIBLY
BECOMING SUBTROPICAL IN NATURE. HOWEVER IT NOW APPEARS THAT ITS
WINDOW FOR BECOMING SUBTROPICAL HAS CLOSED AS IS QUICKLY MOVES
TO THE NE. MODERATE TO HEAVY RAINFALL IS OCCURRING IN THIS SLOW
MOVING AREA OF WEATHER...BERMUDA HAS RECORED 1.28 INCHES OF RAIN
OVER THE PAST 24 HOURS. IN THE EASTERN ATLC...AN ELONGATED UPPER
TROUGH AXIS EXTENDS FROM JUST E OF THE AZORES ALONG 27N31W
21N41W 18N55W WITH A COUPLE EMBEDDED UPPER LOW CENTERS
....ESPECIALLY IN THE SE PORTION OF THE TROUGH AXIS. AT THE
SURFACE...A BROAD RIDGE DOMINATES THE ATLC EAST OF 65W WITH A
1025 MB HIGH LOCATED NEAR 32N48W. ORGANIZED SHOWERS AND TSTMS IN
THE CNTRL AND ERN ATLC ARE CONFINED TO THE ITCZ AND TROPICAL
WAVES.

$$
CANGIALOSI




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