[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 291756
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON SEP 29 2008

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

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

...SPECIAL FEATURES...

SUBTROPICAL STORM LAURA IS CENTERED NEAR 37.4N 47.8W AT 29/1500
UTC OR ABOUT 600 NM SOUTH-SOUTHEAST OF CAPE RACE NEWFOUNDLAND
MOVING WNW AT 7 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 995
MB. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60 KT.
LAURA IS EXPECTED TO GRADUALLY TURN TOWARD THE NORTHWEST AND
THEN TOWARD THE NORTH WITH AN INCREASE IN FORWARD SPEED BY
TUESDAY. TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 240 NM
FROM THE CENTER WITH SCATTERED MODERATE CONVECTION LOCATED
WITHIN 200 NM OF THE CENTER IN THE ERN SEMICIRCLE. SEE THE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT2/
WTNT32 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 26W/27W S OF 15N MOVING W NEAR 10 KT.
BROAD CYCLONIC CURVATURE IS OBSERVED ON VISIBLE SATELLITE
IMAGERY CENTERED NEAR 10N. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION ARE FROM 10N-15N BETWEEN 26W-29W.
SCATTERED MODERATE CONVECTION IS FROM 4N-15N BETWEEN 25W-30W.

A TROPICAL WAVE IS ALONG 42W BETWEEN 10N-20N MOVING W NEAR 5-10
KT. A BROAD LOW-LEVEL CYCLONIC CIRCULATION IS VISIBLE ON
SATELLITE IMAGERY NORTH OF 13N. NO ASSOCIATED SHOWERS OR DEEP
CONVECTION WITH THE WAVE AS IT MOVES BENEATH STRONG SWLY UPPER
FLOW.

A TROPICAL WAVE IS ALONG 56W S OF 16N MOVING W NEAR 5-10 KT.
AN UPPER-LEVEL LOW CENTERED EAST OF THE LEEWARD ISLANDS IS
PRODUCING MODERATE TO STRONG UPPER-LEVEL SWLY FLOW OVER THE
WAVE. STRONG SUBSIDENCE ALOFT IS PREVENTING ANY SHOWERS OR DEEP
CONVECTION FROM DEVELOPING IN THE VICINITY OF THE WAVE.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 12N15W 11N25W 10N29W 6N36W 8N45W
7N53W. IN ADDITION TO CONVECTION ASSOCIATED WITH THE TROPICAL
WAVES...SCATTERED MODERATE CONVECTION IS FROM 4N-8N BETWEEN
17W-20W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
4N-7N BETWEEN 34W-39W.

...DISCUSSION...

GULF OF MEXICO...
A 1010 MB LOW PRESSURE SYSTEM IS LOCATED IN THE S/CENTRAL GULF
OF MEXICO NEAR 23N89W. A SURFACE TROUGH EXTENDS FROM ACROSS
CENTRAL FLORIDA NEAR CAPE CANAVERAL TO THE LOW CENTER SW TO NEAR
CAMPECHE MEXICO. NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS ARE
OVER THE SE GULF S OF 28N AND W OF 90W. THE LOW IS FORECAST TO
MOVE NE...TRACKING ACROSS THE SRN FLORIDA PENINSULA TUESDAY. E
TO SE WINDS OF 10-15 KT ARE OBSERVED IN THE SE GULF AHEAD OF THE
SURFACE TROUGH. A STRONG PRESSURE GRADIENT BETWEEN THIS LOW
PRESSURE AREA AND HIGHER PRESSURE OVER THE WRN GULF AND NE
MEXICO IS PRODUCING NLY WINDS 15-20 KT OVER THE SW GULF AND THE
BAY OF CAMPECHE. NE WINDS OF 10-15 KT COVER THE REMAINDER OF THE
GULF N OF 28N. ALOFT...A MID/UPPER LEVEL TROUGH IS MOVING OVER
THE WRN ATLC WITH ITS AXIS ALONG 93W. UPPER-LEVEL SWLY WINDS
EAST OF THIS TROUGH ARE TRANSPORTING ABUNDANT UPPER LEVEL
MOISTURE ACROSS THE SE GULF TO AID IN SUPPORTING THE PREVIOUSLY
MENTIONED SHOWERS AND THUNDERSTORM ACTIVITY.

CARIBBEAN SEA...
UPPER LEVEL DIVERGENT FLOW BETWEEN THE TROUGH OVER THE WRN GULF
OF MEXICO AND UPPER LEVEL RIDGING ACROSS THE NRN CARIBBEAN
EXTENDING FROM AN UPPER LEVEL HIGH CENTERED OVER THE W ATLC NE
OF THE BAHAMAS IS GENERATING WIDELY SCATTERED SHOWERS AND TSTMS
ACROSS THE CENTRAL AND WRN CARIBBEAN W OF 74W. THE ITCZ AXIS
EXTENDS FROM THE ERN PACIFIC REGION ACROSS THE SW CARIBBEAN SEA
ALONG 10N WHICH IS ALSO AIDING IN DEVELOPMENT OF SCATTERED
SHOWERS AND TSTMS S OF 13N AND W OF 80W...INCLUDING COASTAL
NICARAGUA AND COSTA RICA. THE ERN CARIBBEAN REMAINS UNDER MOSTLY
CLEAR CONDITIONS DUE TO A DRY AND STABLE AIRMASS ALOFT. MODERATE
TRADE WINDS PERSIST THROUGHOUT THE CARIBBEAN THIS AFTERNOON.

ATLANTIC OCEAN...
SUBTROPICAL STORM LAURA IS LOCATED IN THE N/CENTRAL ATLANTIC...
SEE SPECIAL FEATURES SECTION ABOVE. ABUNDANT UPPER-LEVEL
MOISTURE CONTINUES TO STREAM ACROSS THE FLORIDA PENINSULA AND
OVER THE W ATLC WATERS DUE TO STRONG SWLY FLOW AHEAD OF AN UPPER
TROUGH OVER THE GULF OF MEXICO. A SURFACE TROUGH EXTENDS FROM
NEAR 30N78W TO CAPE CANAVERAL FLORIDA AND ACROSS CENTRAL
FLORIDA. SCATTERED SHOWERS WITH EMBEDDED TSTMS ARE ACROSS THE W
ATLC WATERS FROM 26N-32N BETWEEN 74W-80W. AN UPPER-LEVEL HIGH IS
CENTERED NE OF THE BAHAMAS NEAR 24N72W AND IS PROVIDING MODERATE
TO STRONG SUBSIDENCE/DRY AIR S OF 26N AND W OF 58W. THIS
TRANSLATES TO THE SURFACE AS A 1017 MB HIGH...CENTERED NEAR
26N67W. THE ERN ATLANTIC IS DOMINATED BY A SURFACE HIGH PRESSURE
RIDGE EXTENDING SWD FROM THE AZORES TO NEAR 20N. ALOFT...A
TROUGH CONNECTS AN UPPER LOW NEAR 36N42W TO A SECOND UPPER LOW
EAST OF THE LEEWARD ISLANDS CENTERED NEAR 17N58W. WIDELY
SCATTERED SHOWERS ARE FROM 27N-32N BETWEEN 37W-43W E OF THE
UPPER TROUGHING. A UPPER RIDGE COVERS THE REMAINDER OF THE ERN
ATLC E OF 50W AND IS CENTERED ON AN UPPER HIGH NEAR 18N23W.
UPPER LEVEL FLOW AROUND THIS RIDGE CONTINUES TO ENHANCE
CONVECTION ALONG THE ITCZ EAST OF 40W.

$$
HUFFMAN




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