[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 191032
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0945 UTC.

...SPECIAL FEATURES...
HURRICANE GORDON IS CENTERED NEAR 38.1N 38.7W OR ABOUT 545 NM W
OF TERCEIRA IN THE AZORES AT 19/0900 UTC MOVING EAST AT 24 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 970 MB. MAXIMUM SUSTAINED
WIND SPEED IS 90 KT WITH GUSTS TO 110 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 AND ON IN ALL
LIKELIHOOD WILL REMAIN A HURRICANE AS IT NEARS THE AZORES.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERS THE AREA
FROM 36N-40N BETWEEN 35W-40W.

HURRICANE HELENE IS CENTERED NEAR 24.4N 52.1W OR ABOUT 820 MILES
EAST-SOUTHEAST OF BERMUDA AT 19/0900 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 AND THE
CLOUD TOPS HAVE WARMED SOME WHAT. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION COVERS THE AREA FROM 21N-28N BETWEEN 49W-55W.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 38W/39W S OF 20N MOVING W 10-15 KT.
WELL-DEFINED INVERTED-V SIGNATURE WITH ASSOCIATED SCATTERED
MODERATE/ISOLATED STRONG CONVECTION E OF THE WAVE AXIS FROM
10N-14N BETWEEN 35W-39W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N13W 7N21W 10N36W 7N46W INTO THE
CARIBBEAN NEAR 13N62W ACROSS COLOMBIA AND PANAMA INTO THE E
PACIFIC REGION NEAR 8N78W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 90 NM OF THE AXIS E OF 17W TO THE COAST OF
AFRICA AND WITHIN 75 NM OF THE AXIS FROM 37W-40W. CLUSTERS OF
SCATTERED MODERATE CONVECTION ARE FROM 5N-13N BETWEEN 17W-50W.

...DISCUSSION...
GULF OF MEXICO...
DEEP LAYER TROUGH MOVING ACROSS THE CENTRAL US...N MEXICO... AND
THE NW GULF EXTENDS AN ASSOCIATED COLD FRONT INTO THE GULF E OF
LAKE CHARLES LOUISIANA INTO TEXAS NEAR BROWNSVILLE. A
PRE-FRONTAL TROUGH EXTENDS FROM S ALABAMA ACROSS THE MISSISSIPPI
DELTA TO JUST OFF THE MEXICAN COAST NEAR 25N96W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 90 NM OF THE TROUGH
WITH SCATTERED SHOWERS WITHIN 45 NM OF THE COLD FRONT. SMALL BUT
STRONG UPPER LOW IS OVER THE BAY OF CAMPECHE AND COVERS THE FAR
SW GULF GENERATING SCATTERED MODERATE/STRONG CONVECTION S OF 21N
W OF 91W. AN UPPER HIGH IS IN THE NE GULF NEAR 27N87W 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 S FLORIDA PENINSULA AND THE FAR SE GULF E OF
83W. THIS IS GENERATING SHOWERS/ISOLATED SCATTERED THUNDERSTORMS
N OF 24N E OF 87W TO JUST INLAND OVER THE FLORIDA W COAST.

CARIBBEAN SEA...
THE UPPER TROUGH IN THE W ATLC EXTENDS ACROSS CUBA INTO THE NW
CARIBBEAN N OF 18N W OF 78W. 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 JUST S OF THE VIRGIN ISLANDS NEAR 17N65W
EXTENDING A RIDGE WSW TO 13N80W. THIS IS ADVECTING TROPICAL
MOISTURE OVER THE S CARIBBEAN AND GENERATING CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION S OF 14N FROM
71W-79W WITH SCATTERED SHOWERS/THUNDERSTORMS FROM 10N-15N W OF
81W TO INLAND OVER CENTRAL AMERICA. THE REMAINDER OF THE
CARIBBEAN REMAINS RATHER DRY THIS MORNING.

ATLANTIC OCEAN...
BROAD UPPER TROUGH EXTENDS FROM AN UPPER LOW N OF THE REGION
THROUGH 32N71W OVER CUBA NEAR 23N80W WITH CYCLONIC FLOW WITHIN
300 NM OF THE TROUGH AXIS. THIS IS GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS N OF 29N FROM 77W-80W. SURFACE
TROUGH EXTENDS THROUGH 32N70W TO NEAR 26N72W WITH A 1018 MB HIGH
ON EITHER SIDE OF THE SURFACE TROUGH NEAR 26N65W AND 25N78W.
BROAD UPPER HIGH ANCHORED IN THE E CARIBBEAN EXTENDS A RIDGE NE
ALONG 18N62W TO 25N58W 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 IS ELONGATING CONVECTION ASSOCIATED WITH THAT SYSTEM. A
CUT-OFF UPPER LOW IS TO THE E OF HELENE CENTERED NEAR 21N34W AND
COVERS THE AREA FROM 13N-29N BETWEEN 28W-43W. THIS AREA HAS DRY
AIR WITH SMALL AREA OF SCATTERED MODERATE CONVECTION LOCATED IN
THE VICINITY OF THE UPPER LOW WITHIN A 45 NM RADIUS OF 22N31W.
THE REMAINDER OF THE E ATLC HAS NO SHOWER ACTIVITY E OF 44W.
REMAINDER OF THE E ATLC IS DOMINATED BY AN UPPER HIGH ANCHORED
OFF THE COAST OF AFRICA NEAR 16N18W AND COVERS THE AREA FROM
JUST S OF THE CANARY ISLANDS E OF 28W. A SMALL AREA OF DUST HAS
MOVED OFF AFRICA FROM 14N-24N E OF 30W AND ENCOMPASSES THE CAPE
VERDE ISLANDS.

$$
WALLACE





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