[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 141027
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU SEP 14 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
0345 UTC.

...SPECIAL FEATURES...
HURRICANE GORDON IS CENTERED NEAR 28.7N 56.6W AT 14/0900 UTC
MOVING NORTH-NORTHEAST AT 11 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 955 MB. MAXIMUM SUSTAINED WIND SPEED IS 105 KT WITH
GUSTS TO 130 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. GORDON
STILL HAS A SMALL VERY DISTINCT EYE WITH UNIFORM CONVECTION
SURROUNDING THE EYE. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 90 NM FROM THE CENTER IN ALL QUADRANTS.
SCATTERED MODERATE CONVECTION CONTINUES WITHIN 150 NM OF THE
CENTER IN THE N QUADRANT AND WITHIN 200 NM IN THE E QUADRANT.

TROPICAL STORM HELENE IS CENTERED NEAR 13.7N 34.7W AT 14/0900
MOVING WEST AT 19 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005
MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT.
SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. HELENE REMAINS FAIRLY
UNORGANIZED DESPITE THE WIND SPEED INCREASE. THE DEEPEST
CONVECTION IS REMOVED FROM THE CENTER. CLUSTERS OF SCATTERED
MODERATE/STRONG CONVECTION COVER A BROAD AREA FROM 8N-19N
BETWEEN 26W-39W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 46W S OF 13N MOVING W 10-15 KT. LOW
AMPLITUDE WAVE EMBEDDED WITHIN A LAYER OF AFRICAN DUST THUS NO
ASSOCIATED CONNECTION.

TROPICAL WAVE IS ALONG 54W/55W S OF 14N MOVING W 10-15 KT. WEAK
WAVE SIGNATURE AS THE WAVE MOVES TOWARD AN AREA OF UPPER
DIFFLUENCE THAT EXTENDS NE OF THE LESSER ANTILLES. ASSOCIATED
CONVECTION IS WITHIN THE ITCZ.

TROPICAL WAVE IS ALONG 64W/65W S OF 18N MOVING W 15 KT.
WELL-DEFINED LOW LEVEL INVERTED-V SATELLITE SIGNATURE IS
OBSERVED OVER THE E CARIBBEAN. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS FROM 14N18N BETWEEN 63W-66W.

TROPICAL WAVE IS ALONG 74W/75W S OF 18N MOVING W 15 KT. WEAK LOW
LEVEL INVERTED-V SATELLITE SIGNATURE IS OBSERVED OVER THE
CENTRAL CARIBBEAN. WAVE IS EMBEDDED WITHIN VERY DRY AIR THUS NO
ASSOCIATED CONVECTION.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 14N16W 13N26W 14N31W THEN ALONG
10N35W 8N44W 12N62W ACROSS THE N PORTION OF SOUTH AMERICA AND
PANAMA NEAR 9N83W INTO THE E PACIFIC REGION. SCATTERED
MODERATE/STRONG CONVECTION IS WITHIN 150 NM S OF THE AXIS FROM
17W-27W AND WITHIN 150 NM N OF THE AXIS E OF 22W TO THE COAST OF
AFRICA. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
6N-10N BETWEEN 47W-53W AND SCATTERED MODERATE CONVECTION IS
WITHIN 60 NM OF THE AXIS FROM 55W-58W.

...DISCUSSION...

GULF OF MEXICO...
BROAD DEEP LAYERED TROUGH COVERS THE E US AND ALONG THE N GULF
COAST ANCHORED BY AN UPPER LOW MOVING JUST S OF THE GREAT LAKES
REGION. THE ASSOCIATED FRONTAL BOUNDARY EXTENDS INTO THE GULF
THROUGH A 1009 MB LOW OVER THE FLORIDA PANHANDLE NEAR
TALLAHASSEE SW TO 28N86W WHERE IT BECOMES NEAR STATIONARY THE
TEXAS/MEXICO BORDER. ISOLATED SHOWERS ARE OVER THE N GULF N OF
THE FRONT E OF 90W. UPPER RIDGE EXTENDS ACROSS THE REMAINDER OF
THE GULF ANCHORED BY AN UPPER HIGH OVER CENTRAL MEXICO ACROSS
TAMPICO MEXICO TO JUST S OF TAMPA FLORIDA INTO THE W ATLC. THIS
IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM
24N-28N E OF 84W TO INLAND OVER S FLORIDA AND SCATTERED SHOWERS
FROM 23N-27N W OF 94W TO INLAND OVER NE MEXICO. MID LEVEL LOW IS
IN THE SW GULF NEAR 21N94W GENERATING ISOLATED SHOWERS S OF 21N
INTO THE BAY OF CAMPECHE W OF 93W TO OVER MEXICO.

CARIBBEAN SEA...
W CARIBBEAN IS DOMINATED BY NE UPPER FLOW FROM THE UPPER RIDGE
THAT EXTENDS ACROSS THE GULF OF MEXICO INTO THE W ATLC. THIS IS
PROVIDING DRY AIR ACROSS THE AREA INCLUDING THE TROPICAL WAVE
ALONG 74W/75W. AN UPPER TROUGH EXTENDS FROM THE W ATLC ACROSS
HISPANIOLA TO CENTRAL COSTA RICA. E CARIBBEAN IS DOMINATED BY S
UPPER FLOW FROM AN UPPER RIDGE ANCHORED IN THE TROPICAL ATLC.
THIS RIDGE IS DRAWING ABUNDANT TROPICAL MOISTURE ACROSS THE E
CARIBBEAN AND ENHANCING CONVECTION ASSOCIATED WITH THE TROPICAL
WAVE ALONG 64W/65W AND GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS OVER THE NE CARIBBEAN N OF 16N E OF 64W INCLUDING
THE VIRGIN AND N LEEWARD ISLANDS. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 90 NM ALONG THE
COAST OF COLOMBIA AND PANAMA DUE TO THE PROXIMITY OF THE ITCZ
AXIS.

ATLANTIC OCEAN...
BROAD DEEP LAYERED TROUGH THAT COVERS THE E US AND THE N GULF
COAST ANCHORED BY AN UPPER LOW MOVING JUST S OF THE GREAT LAKES
REGION AND IS EXTENDING INTO THE NW ATLC. THE ASSOCIATED FRONTAL
BOUNDARY EXTENDS INTO THE GULF IS APPROACHING THE SE US COAST
GIVING THE AREA SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF
28N FROM 77W-80W. UPPER RIDGE AXIS EXTENDS FROM THE GULF OF
MEXICO INTO THE W ATLC ACROSS FLORIDA JUST S OF DAYTONA BEACH TO
NEAR 31N68W. BENEATH THIS UPPER RIDGE IS A SURFACE TROUGH THAT
EXTENDS FROM 32N71W THROUGH A 1010 MB LOW NEAR 28N73W ACROSS THE
CENTRAL BAHAMAS TO NEAR 24N78W. THIS IS GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS NE OF THE LOW FROM 27N-32N
BETWEEN 68W-73W. AN UPPER LOW IS IN THE W ATLC JUST TO THE E OF
THE RIDGE NEAR 24N68W WITH THE UPPER TROUGH EXTENDING S ACROSS
HISPANIOLA INTO THE CARIBBEAN GENERATING SCATTERED SHOWERS FROM
23N-29N BETWEEN 62W-70W. BROAD UPPER RIDGE COVERS THE W/CENTRAL
ATLC ANCHORED IN THE TROPICS NEAR 18N57W COVERING THE AREA S OF
25N FROM 46W-66W. ABUNDANCE OF TROPICAL MOISTURE IS BEING DRAWN
ACROSS THE E CARIBBEAN AND WITH SUFFICIENT DIFFLUENCE TO
GENERATE AN AREA OF SCATTERED SHOWERS/THUNDERSTORMS FROM 14N-21N
BETWEEN 55W-64W. GORDON IS N OF THIS UPPER RIDGE. AN UPPER
TROUGH EXTENDS INTO THE CENTRAL ATLC NEAR 32N42W S TO 22N45W.
HOWEVER...DUE TO THE DRY AIR IN PLACE NO SHOWER ACTIVITY IS
EVIDENT. BROAD UPPER RIDGE COVERS THE REMAINDER OF THE ATLC E OF
32W ANCHORED NEAR 28N28W EXTENDING E TO OVER THE CANARY ISLANDS
AND NW AFRICA. AT THE SURFACE...A RIDGE COVERS THE ATLC N OF 20N
E OF 50W WITH A 1028 MB HIGH SE OF THE AZORES. THE FIRST VISIBLE
SATELLITE IMAGES SHOWS A LARGE AREA OF AFRICA DUST FROM THE ITCZ
TO 30N BETWEEN 35W-50W WITH HELENE JUST TO THE E OF THIS DUST.

$$
WALLACE






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