[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 200558
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED SEP 20 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0315 UTC.

...SPECIAL FEATURES...
HURRICANE GORDON IS CENTERED NEAR 37.6N 26.3W OR ABOUT 35 NM
WEST-SOUTHWEST OF THE ISLAND OF SAO MIGUEL IN THE EASTERN AZORES
AT 20/0600 UTC MOVING EAST AT 29 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 987 MB. MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH
GUSTS TO 80 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC OR THE PUBLIC ADVISORY
UNDER MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. GORDON IS PASSING
OVER THE SOUTHERN MOST ISLANDS OF THE AZORES. GORDON IS EXPECTED
TO MERGE WITH A FRONTAL BOUNDARY LATER TODAY LOSING ITS TROPICAL
CHARACTERISTICS AND BECOME A STRONG EXTRATROPICAL STORM AS IT
APPROACHES SPAIN/PORTUGAL. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION COVERS THE AREA FROM 36N-39N BETWEEN 25W-28W.

HURRICANE HELENE IS CENTERED NEAR 24.6N 54.8W OR ABOUT 700 MILES
SOUTHEAST OF BERMUDA AT 20/0300 UTC MOVING WEST AT 8 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 958 MB. MAXIMUM SUSTAINED
WIND SPEED IS 95 KT WITH GUSTS TO 115 KT. SEE THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC
FOR MORE DETAILS. HELENE IS NOW A CATEGORY TWO HURRICANE AND HAS
THE POTENTIAL OF BECOMING A MAJOR HURRICANE AGAIN AFTER IT
COMPLETES THE EYEWALL REPLACEMENT THAT IS CURRENTLY UNDERGOING.
SCATTERED STRONG CONVECTION IS WITHIN 45 NM OF THE CENTER IN ALL
QUADRANTS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERS
THE AREA FROM 22N-27N BETWEEN 51W-56W.

...TROPICAL WAVES...
TROPICAL WAVE IS OVER THE CAPE VERDE ISLANDS ALONG 23W/24W S OF
18N MOVING W 15-20 KT. BROAD MID LEVEL CURVATURE IS OBSERVED ON
INFRARED SATELLITE IMAGERY. SCATTERED MODERATE/STRONG CONVECTION
IS W OF THE WAVE AXIS FROM 11N-14N BETWEEN 26W-29W.

TROPICAL WAVE IS ALONG 38W/39W S OF 20N MOVING W 10-15 KT.
WELL-DEFINED INVERTED-V SIGNATURE. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE AXIS FROM 11N-16N
BETWEEN 38W-44W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N14W 10N19W 11N23W 9N31W 11N38W
7N50W 8N61W ACROSS N PORTION OF SOUTH AMERICA ALONG 10N80W INTO
THE E PACIFIC REGION NEAR 9N83W. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS WITHIN 120 NM OF LINE 7N25W-6N30W-8N34W...
WITHIN 75 NM OF LINE 15N35W-14N38W...AND WITHIN 60 NM OF THE
AXIS FROM 25W-29W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE
FROM 5N-10N E OF 23W TO INLAND OVER AFRICA AND FROM 8N-13N
BETWEEN 47W-55W.

...DISCUSSION...
GULF OF MEXICO...
DEEP LAYER TROUGH IS MOVING OVER THE E US AND THE N GULF N OF
27N EXTENDING AN ASSOCIATED COLD FRONT INTO THE GULF OVER
CENTRAL GEORGIA AND THE FLORIDA PANHANDLE NEAR TALLAHASSEE TO A
1013 MB LOW IN THE N/CENTRAL GULF NEAR 27N93W TO THE MEXICAN
COAST BETWEEN TAMPICO AND THE TEXAS BORDER CONTINUING AS A
STATIONARY FRONT UP THE E SLOPES OF THE SIERRA MADRE MOUNTAINS.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 60 NM OF THE
COLD FRONT. AN UPPER HIGH IN THE BAY OF CAMPECHE EXTENDS AN
UPPER RIDGE NE AHEAD OF THE UPPER TROUGH ACROSS THE GULF ALONG
25N85W INTO THE W ATLC OVER CENTRAL FLORIDA. A BROAD UPPER
TROUGH IN THE W ATLC IS PROVIDING THE DIFFLUENCE TO GENERATE
SHOWERS/SCATTERED THUNDERSTORMS OVER S FLORIDA AND THE FLORIDA
KEYS FROM 24N-27N E OF 84W INTO THE W ATLC.


CARIBBEAN SEA...
NARROW UPPER TROUGH IN THE W ATLC EXTENDS ACROSS CENTRAL CUBA SW
TO THE GULF OF HONDURAS OVER THE NW CARIBBEAN N OF 16N W OF 78W.
UPPER HIGH OVER THE REMAINDER OF THE CARIBBEAN IS ANCHORED JUST
S OF HISPANIOLA NEAR 15N72W EXTENDING A RIDGE SW TO 12N83W AND
NE INTO THE CENTRAL ATLC NEAR 21N60W. THIS IS ADVECTING TROPICAL
MOISTURE OVER THE S CARIBBEAN AND GENERATING ISOLATED SHOWERS S
OF 15N W OF 72W. THE REMAINDER OF THE CARIBBEAN REMAINS RATHER
DRY TONIGHT.

ATLANTIC OCEAN...
UPPER RIDGE ANCHORED IN THE GULF OF MEXICO EXTENDS ACROSS
CENTRAL FLORIDA INTO THE W ATLC NNE TO BEYOND 32N76W. NARROW
UPPER TROUGH EXTENDS FROM AN UPPER LOW N OF THE REGION THROUGH
32N68W ACROSS CENTRAL CUBA NEAR 22N78W GENERATING SCATTERED
SHOWERS/THUNDERSTORMS NW OF LINE FROM 24N79W ACROSS THE N
BAHAMAS TO BEYOND 32N74W. WEAK SURFACE TROUGH EXTENDS THROUGH
32N66W TO NEAR 23N71W WITH A 1019 MB HIGH OVER THE N/CENTRAL
BAHAMAS NEAR 25N76W. UPPER HIGH ANCHORED IN THE CARIBBEAN
EXTENDS A RIDGE NE ACROSS THE VIRGIN ISLANDS TO 21N60W JUST W OF
HURRICANE HELENE. THIS IS GIVING THE E CARIBBEAN AND THE W
TROPICAL ATLC VERY DRY AIR. THE UPPER RIDGE ASSOCIATED WITH
HURRICANE HELENE HAS BECOME MORE SYMMETRICAL OVER THE PAST 24
HOURS ALLOWING THE CONVECTION ASSOCIATED WITH HELENE TO BECOME
MORE SYMMETRICAL AND THE OUTFLOW GOOD IN ALL QUADRANTS. THE
CUT-OFF UPPER LOW E OF HELENE IS ELONGATING NE/SW AND IS
CENTERED NEAR 22N36W WITH A TROUGH AXIS EXTENDING FROM 30N30W TO
16N42W. THIS AREA HAS DRY AIR WITH SMALL AREA OF SCATTERED
MODERATE CONVECTION LOCATED JUST TO THE W OF THE UPPER LOW
WITHIN 45 NM OF LINE 25N34W-20N37W. AN UPPER TROUGH IS DIPPING S
ACROSS THE CANARY ISLANDS TO INLAND OVER NW AFRICA DISTORTING
UPPER HIGH ANCHORED OFF THE COAST OF AFRICA NEAR 18N18W AND
COVERS THE AREA FROM JUST S OF 24N E OF 30W. AT THE SURFACE...A
1022 MB HIGH IS LOCATED NEAR 29N36W WITH A RIDGE EXTENDING E TO
THE CANARY ISLANDS. THE SMALL AREA OF DUST HAS MOVED OFF AFRICA
FROM 10N-24N E OF 35W AND ENCOMPASSES THE CAPE VERDE ISLANDS.

$$
WALLACE




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