[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 291744
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT SEP 29 2012

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND 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
1645 UTC.

...SPECIAL FEATURES...

HURRICANE NADINE IS LOCATED NEAR 33.3N 36.2W AT 29/1500 UTC.
THIS POSITION IS LOCATED ABOUT 530 NM WSW OF THE AZORES ISLANDS.
NADINE IS MOVING NNW NEAR 12 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 988 MB. MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH
GUST TO 80 KT. PLEASE SEE LATEST NHC FORECAST/ ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 32N-36N
BETWEEN 34W-39W.

...TROPICAL WAVES...

TROPICAL WAVE IS NEARING THE CAPE VERDE ISLANDS ALONG 17N18W TO
10N25W. THIS WAVE IS CURRENTLY MOVING SLOWLY AT ABOUT 5-10 KT.
IT WILL CONTINUE TO MOVE SLOWLY FOR LIKELY THE NEXT 24 HOURS
BEFORE GAINING A FASTER WESTWARD MOTION. THE WAVE IS EMBEDDED
WITHIN A BROAD AREA OF MOISTURE COVERING THE EASTERN TROPICAL
ATLC. MAXIMUM MOISTURE VALUES ARE NOTED NEAR THE WAVE AXIS. AN
ASCAT SCATTEROMETER PASS FROM EARLIER THIS MORNING INDICATES
THAT LOW LEVEL CYCLONIC FLOW IS AROUND THE NE PORTION OF THE
WAVE. DUE TO THE BROAD NATURE OF THE WAVE...ISOLATED MODERATE
CONVECTION RANGES FROM THE COAST OF AFRICA TO 30W WITH SCATTERED
MODERATE/ISOLATED STRONG CONVECTION JUST WEST OF THE AXIS FROM
13N-15N BETWEEN 21W-24W.

TROPICAL WAVE IS ALONG 17N36W TO 10N41W MOVING W NEAR 10 KT. IT
LIES ON THE WEST SIDE OF A SURGE OF DEEP LAYER MOISTURE PRESENT
IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/STRONG
CONVECTION IS NEAR THE ITCZ AXIS FROM 5N-9N BETWEEN 38W-42W.
SCATTERED MODERATE CONVECTION IS E OF THE WAVE AXIS FROM 14N-18N
BETWEEN 32W-35W.

TROPICAL WAVE IS IN THE WESTERN CARIBBEAN ALONG 21N83W TO 15N84W
MOVING W 5-10 KT. THE WAVE LIES ON THE WESTERN EDGE OF AN AREA
OF ENHANCED MOISTURE PRESENT ACROSS THE WESTERN AND CENTRAL
CARIBBEAN. THE WAVE ALSO LIES UNDERNEATH THE AXIS OF A NARROW
UPPER LEVEL TROUGH. THIS UPPER TROUGH IS MAKING IT DIFFICULT TO
DISTINGUISH EXACTLY WHERE THE WAVE AXIS IS. CONVECTION TO THE
EAST OF THE WAVE IS LIKELY MORE ATTRIBUTED TO THE UPPER TROUGH
THAN THE WAVE. THE WAVE IS NOW MOVING TOWARD THE WESTERN AND DRY
SIDE OF THE UPPER TROUGH WHICH IS INHIBITING CONVECTION NEAR THE
WAVE AXIS. CONVECTION ASSOCIATED WITH THE UPPER TROUGH IS
DESCRIBED IN THE CARIBBEAN SEA SECTION.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA TO THE COAST OF
GUINEA-BISSAU AT 11N16W CONTINUING OVER ATLC WATERS ALONG 9N21W
9N34W. THE ITCZ BEGINS FROM 9N34W ALONG 9N40W 8N50W 9N57W.
CONVECTION ACROSS THE EASTERN AND CENTRAL TROPICAL ATLC ARE
ASSOCIATED WITH TROPICAL WAVES. SEE TROPICAL WAVE SECTION ABOVE.
A SURFACE TROUGH IS ANALYZED NORTH OF THE ITCZ ALONG 14N52W TO
10N53W. THIS TROUGH MORE OUTLINES AN AREA OF WIND SPEED
CONVERGENCE WITH STRONGER WINDS TO THE EAST AND WEAKER WINDS TO
THE WEST. THE TROUGH IS BEING ENHANCED BY AN UPPER LEVEL TROUGH
PRESENT ACROSS THE CENTRAL ATLC THAT EXTENDS SOUTHWARD ALONG
52W. THIS COMBINATION IS HELPING PRODUCE SCATTERED
MODERATE/STRONG CONVECTION FROM 9N-12N BETWEEN 50W-55W.

...DISCUSSION...

GULF OF MEXICO...
WEAK SURFACE RIDGING IS ACROSS THE GULF OF MEXICO EXTENDING FROM
A 1016 MB HIGH CENTER OVER THE NE GULF NEAR 29N87W. THE RIDGE
ALONG WITH A SMALL AREA OF DRY AIR ALOFT AROUND AN UPPER LEVEL
RIDGE ACROSS THE BASIN IS HELPING PRODUCE FAIR WEATHER OVER A
GOOD PORTION OF THE CENTRAL..EASTERN...AND SOUTHERN GULF
INCLUDING FLORIDA AND THE YUCATAN PENINSULA. THE NW GULF IS A
DIFFERENT STORY WHERE NUMEROUS SHOWERS/SCATTERED THUNDERSTORMS
ARE PRESENT ACROSS TEXAS AND SOUTHERN LOUISIANA AND EXTEND
OFFSHORE N OF 27N W OF 88W. THE ACTIVITY IS ASSOCIATED WITH AN
UPPER LEVEL TROUGH EXTENDING DOWN WESTERN TEXAS INTO CENTRAL
MEXICO PLACING THE NW GULF UNDERNEATH THE UPPER TROUGHS
DIFFLUENT SIDE. WIND SPEED CONVERGENCE ALONG THE COASTLINE IS
ALSO CONTRIBUTING TO THE ACTIVITY AS STRONGER RETURN FLOW HITS
LIGHTER WINDS ALONG THE COAST. THIS UPPER TROUGH WILL SUPPORT A
LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT THAT IS FORECAST
TO ENTER GULF WATERS EARLY SUNDAY MORNING. SHOWERS/THUNDERSTORMS
AND GUSTY WINDS ARE LIKELY ALONG THE FRONT AXIS.

CARIBBEAN SEA...
A TROPICAL WAVE IS MOVING THROUGH THE WESTERN CARIBBEAN ALONG
84W...BUT IS NOT CAUSING MUCH ACTIVE WEATHER. HOWEVER...A NARROW
UPPER LEVEL TROUGH...NEARLY CUTOFF LOW...IS PRODUCING A LARGE
AREA OF SHOWERS/THUNDERSTORMS EAST OF THE TROPICAL WAVE.
NUMEROUS SHOWERS/SCATTERED THUNDERSTORMS ARE BETWEEN JAMAICA AND
HISPANIOLA FROM 15N-19N BETWEEN 74W-77W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE SOUTH OF CENTRAL CUBA FROM
18N-21N BETWEEN 79W-82W. SIMILAR ACTIVITY IS OFF THE COASTS OF
NICARAGUA AND COSTA RICA FROM 10N-16N BETWEEN 80W-83W. THE
REMAINDER OF THE CENTRAL AND EASTERN CARIBBEAN ARE EXPERIENCING
FAIR CONDITIONS AND MOSTLY CLEAR SKIES DUE TO DRY AIR ALOFT
AROUND AN UPPER LEVEL RIDGE ALONG 73W COVERING THE REMAINDER OF
THE BASIN. TRADEWIND FLOW OF 15-20 KT IS PRESENT ACROSS THE
MAJORITY OF THE AREA WITH STRONGER WINDS TO 25 KT N OF WESTERN
VENEZUELA. EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS WITH
CONTINUED SHOWER/THUNDERSTORM ACTIVITY IN THE WESTERN CARIBBEAN
AS THE UPPER TROUGH REMAINS SOMEWHAT STATIONARY.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS IMPACTING THE WESTERN ATLC WITH AXIS
ALONG 75W. DIFFLUENCE ALOFT AROUND THE EAST SIDE OF THE TROUGH
IS SUPPORTING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ACROSS
THE BAHAMAS FROM N OF CUBA TO 25N BETWEEN 72W-78W WITH A FEW
ISOLATED SHOWERS THROUGH THE FLORIDA STRAITS. THE UPPER TROUGH
ALSO SUPPORTS A WEAK SURFACE TROUGH ALONG 30N72W TO
27N75W...WHICH IS PRODUCING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS N OF 26N BETWEEN 68W-72W. DESPITE THE PRESENCE OF
AN UPPER LEVEL RIDGE OVER THE REMAINDER OF THE WEST ATLC...A
PAIR OF SURFACE TROUGHS ALONG 25N67W TO 22N69W AND 24N63W TO
21N65W ARE SUPPORTING AN AREA OF SHOWERS/THUNDERSTORMS FROM
22N-24N BETWEEN 64W-67W. THE UPPER RIDGE SUPPORTS A WEAK SURFACE
RIDGE ACROSS THE CENTRAL ATLC AROUND A 1023 MB HIGH NEAR 32N53W.
HOWEVER...A BROAD UPPER TROUGH 51W IS SUPPORTING AN AREA OF
SHOWERS/POSSIBLE THUNDERSTORMS FROM 19N-30N BETWEEN 51W-58W.
THIS UPPER TROUGH IS ALSO RESPONSIBLE FOR AN AREA OF ACTIVITY
NEAR A SURFACE TROUGH N OF THE ITCZ REGION. THIS SURFACE TROUGH
IS DESCRIBED IN THE ITCZ SECTION ABOVE. ANOTHER UPPER LEVEL
RIDGE ALONG 30W SUPPORTS A WEAK 1022 MB HIGH NEAR 25N37W...WHICH
IS PROVIDING FAIR CONDITIONS ACROSS THE REMAINDER OF THE EASTERN
ATLC. HURRICANE NADINE IS CENTERED N OF THE HIGH CENTER NEAR THE
BOUNDARY OF THE DISCUSSION AREA. SEE SPECIAL FEATURES FOR MORE
DETAILS. A BROAD UPPER TROUGH COVERS THE REMAINDER OF THE
BASIN...BUT IS NOT CAUSING ANY ACTIVE WEATHER IN THE DISCUSSION
AREA.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$

WALTON/DELGADO





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