[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 190551
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE SEP 19 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 38.1N 40.2W OR ABOUT 615 NM W
OF TERCEIRA IN THE AZORES AT 19/0600 UTC MOVING EAST AT 24 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 972 MB. MAXIMUM SUSTAINED
WIND SPEED IS 85 KT WITH GUSTS TO 105 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. ON THIS TRACK GORDON WILL BE NEAR THE AZORES LATER THIS
AFTERNOON. GORDON IS A HIGH LATITUDE SYSTEM BUT REMAINS
IMPRESSIVE ALTHOUGH THE EYE HAS BECOME MORE RAGGED OVER THE PAST
FEW HOURS. GORDON IN ALL LIKELIHOOD WILL REMAIN A HURRICANE AS
IT APPROACHES THE AZORES. NUMEROUS MODERATE/ISOLATED STRONG
CONVECTION COVERS THE AREA FROM 26N-40N BETWEEN 38W-43W.

HURRICANE HELENE IS CENTERED NEAR 24.2N 51.4W OR ABOUT 860 MILES
EAST-SOUTHEAST OF BERMUDA AT 19/0300 UTC MOVING WEST-NORTHWEST
AT 7 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 960 MB. MAXIMUM
SUSTAINED WIND SPEED IS 100 KT WITH GUSTS TO 120 KT. SEE THE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/
WTNT23 KNHC FOR MORE DETAILS. HELENE IS A CATEGORY THREE
HURRICANE AND HAS THE POTENTIAL OF BECOMING A CATEGORY FOUR.
HOWEVER...IT IS NOT EXPECTED TO IMPACT ANY LAND MASS ON ITS
CURRENT FORECASTED TRACK. CONVECTION IS ELONGATED N/S ALTHOUGH
THE DEEPEST CONVECTION IS SURROUNDING AN IMPRESSIVE 20-25 NM
EYE. SCATTERED STRONG CONVECTION IS WITHIN 45 NM OF THE CENTER
IN THE W QUADRANT. SCATTERED MODERATE/ ISOLATED STRONG
CONVECTION COVERS THE REMAINDER OF THE AREA FROM 21N-28N BETWEEN
48W-54W.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 37W/38W S OF 20N MOVING W 10-15 KT.
WELL-DEFINED INVERTED-V SIGNATURE WITH ASSOCIATED SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS E OF THE WAVE AXIS FROM 10N-14N
BETWEEN 34W-38W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N13W 9N22W 7N34W 12N47W 9N61W
ACROSS N PORTION OF SOUTH AMERICA AND SW CARIBBEAN INTO THE E
PACIFIC REGION NEAR 9N82W. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION ARE FROM 5N-12N E OF 48W TO THE COAST
OF AFRICA.

...DISCUSSION...
GULF OF MEXICO...
DEEP LAYER TROUGH MOVING ACROSS THE CENTRAL US AND N MEXICO
EXTENDS AN ASSOCIATED COLD FRONT INTO THE GULF NEAR LAKE CHARLES
LOUISIANA INTO TEXAS BETWEEN CORPUS CHRISTI AND BROWNSVILLE. A
PRE-FRONTAL TROUGH IS OVER THE W GULF FROM THE MISSISSIPPI DELTA
TO JUST OFF THE MEXICAN COAST NEAR TAMPICO. SCATTERED SHOWERS
ARE WITHIN 60 NM OF THE TROUGH. A SMALL UPPER LOW IS OVER THE
BAY OF CAMPECHE AND COVERS THE FAR SW GULF. AN UPPER HIGH IS IN
THE NE GULF NEAR 27N89W WITH THE UPPER RIDGE EXTENDING NE AHEAD
OF THE UPPER TROUGH AND EXTENDS ACROSS THE GULF SW TO 23N92W. A
BROAD UPPER TROUGH IN THE W ATLC EXTENDS OVER THE FLORIDA
PENINSULA AND THE FAR SE GULF E OF 84W. THIS IS GENERATING
SHOWERS/SCATTERED THUNDERSTORMS N OF 24N E OF 88W TO THE FLORIDA
COAST WITH SCATTERED SHOWERS S OF 24N E OF 85W.

CARIBBEAN SEA...
THE UPPER TROUGH IN THE W ATLC EXTENDS ACROSS CUBA INTO THE NW
CARIBBEAN GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
OVER CUBA. AN UPPER RIDGE EXTENDS FROM OVER S MEXICO AND CENTRAL
AMERICA INTO THE W CARIBBEAN OVER BELIZE TO THE TIP OF HONDURAS/
NICARAGUA. A MUCH LARGER UPPER HIGH IN THE E CARIBBEAN IS
ANCHORED OVER THE LEEWARD ISLANDS NEAR 18N62W EXTENDING A RIDGE
SW TO THE COAST OF COLOMBIA/PANAMA. THIS IS ADVECTING TROPICAL
MOISTURE OVER THE S CARIBBEAN AND GENERATING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS S OF 14N FROM 72W-80W. THE REMAINDER OF
THE CARIBBEAN REMAINS RATHER DRY TONIGHT WITH THE EXCEPTION OF
SOME ISOLATED THUNDERSTORMS THAT DEVELOPED EARLIER OVER HAITI
AND JAMAICA.

ATLANTIC OCEAN...
BROAD UPPER TROUGH EXTENDS FROM AN UPPER LOW N OF THE REGION
THROUGH 32N73W OVER CUBA NEAR 23N80W WITH CYCLONIC FLOW WITHIN
300 NM OF THE TROUGH AXIS. THIS IS GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS OVER CUBA AND THE BAHAMAS W OF
76W INTO THE STRAITS OF FLORIDA. A WEAK SURFACE TROUGH EXTENDS
THROUGH 32N68W TO OVER THE BAHAMAS NEAR 24N75W. BROAD UPPER HIGH
ANCHORED OVER THE LEEWARD ISLANDS NEAR 18N62W EXTENDS A RIDGE NE
TO 24N56W 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 IS ELONGATED N/S AND THIS IS
ELONGATING CONVECTION ASSOCIATED WITH THAT SYSTEM. A CUT-OFF
UPPER LOW IS TO THE E OF HELENE CENTERED NEAR 22N32W AND COVERS
THE AREA FROM 13N-28N BETWEEN 26W-42W. A WEAK SURFACE TROUGH...
PREVIOUSLY A SURFACE LOW...EXTENDS ALONG 28W FROM 17N26N. THIS
AREA HAS DRY UPPER AIR...THUS NO ASSOCIATED SHOWERS/
THUNDERSTORMS. REMAINDER OF THE E ATLC IS DOMINATED BY AN UPPER
HIGH ANCHORED ALONG THE COAST OF AFRICA NEAR SENEGAL AND COVERS
THE AREA S OF THE CANARY ISLANDS E OF 26W.

$$
WALLACE


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