[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 160458
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT SEP 16 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 31.3N 53.4W AT 16/0300 UTC
MOVING NORTH-NORTHEAST AT 4 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 980 MB. MAXIMUM SUSTAINED WIND SPEED IS 75 KT WITH
GUSTS TO 90 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.
GORDON HAS REMAINED NEAR STATIONARY OVER THE PAST SEVERAL HOURS
AND THE EYE IS LESS DISTINCT ON SATELLITE IMAGERY AND OFTEN
CLOUD COVERED. CLOUD TOP TEMPERATURES HAVE WARMED CONSIDERABLY
OVER THE PAST 24 HOURS GIVING THE APPEARANCE OF LESSER
CONVECTION. THUS...OVERCAST CLOUDS WITH SCATTERED MODERATE
CONVECTION ARE WITHIN 120/150 NM FROM THE CENTER IN ALL
QUADRANTS.

TROPICAL STORM HELENE IS CENTERED NEAR 17.2N 43.7W AT 16/0300
MOVING WEST-NORTHWEST AT 12 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 992 MB. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH
GUSTS TO 75 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS.
HELENE HAS GOOD OUTFLOW IN ALL QUADRANTS BUT WITH THE
ENTRAINMENT OF DRY AIR INTO THE SYSTEM ONLY SLOW INTENSIFICATION
IS EXPECTED OVER THE NEXT 24 HOURS. SCATTERED/NUMEROUS STRONG
CONVECTION IS WITHIN 30/45 NM RADIUS OF 18N43W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION COVERS THE REMAINDER OF THE
AREA WITHIN 120 NM OF LINE 19N39W-16N46W.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 20W/21W S OF 20N WITH A 1012 MB LOW ALONG
THE WAVE NEAR 15N MOVING W NEAR 10 KT. BROAD MID LEVEL ROTATION
ASSOCIATED WITH THE WAVE WITH CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION FROM 14N-19N E OF 23W TO THE COAST OF
AFRICA.

TROPICAL WAVE IS ALONG 75W/76W S OF 17N MOVING W 15 KT. BROAD
WELL-DEFINED LOW LEVEL INVERTED-V SATELLITE SIGNATURE IS
OBSERVED OVER THE CENTRAL CARIBBEAN AS THE WAVE PASSES BENEATH
AN UPPER RIDGE WHICH IS ENHANCING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS S OF 13N FROM 74W-78W.

TROPICAL WAVE IS ALONG 83W/84W S OF 17N MOVING W 10 KT. LOW
LEVEL INVERTED-V SATELLITE SIGNATURE IS OBSERVED IN THE E
PACIFIC REGION AS THE N PORTION IS MOVING INLAND OVER CENTRAL
AMERICA. WAVE IS BENEATH THE WESTERN EDGE OF AN UPPER RIDGE WITH
NO ASSOCIATED SHOWERS/CONVECTION.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 15N16W 12N26W 16N36W THEN ALONG
12N47W 10N58W INTO THE CARIBBEAN ALONG 10N63W ACROSS THE N
PORTION OF SOUTH AMERICA AND PANAMA INTO THE E PACIFIC REGION
NEAR 9N82W. SCATTERED STRONG CONVECTION IS WITHIN A 45 NM RADIUS
OF 16.5N40W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
FROM 13N-18N BETWEEN 36W-40W WITH CLUSTERS OF SIMILAR CONVECTION
FROM 11N-16N BETWEEN 40W-48W.

...DISCUSSION...

GULF OF MEXICO...
BROAD DEEP LAYERED TROUGH COVERS THE E US...THE W ATLC ANCHORED
BY AN UPPER LOW MOVING OFF THE NE COAST COVERS THE NE GULF N OF
26N E OF 87W WITH ASSOCIATED FRONTAL BOUNDARY IN THE W ATLC.
BROAD UPPER RIDGE EXTENDS ACROSS THE W GULF ANCHORED BY AN UPPER
HIGH ASSOCIATED WITH A HURRICANE OFF THE W COAST OF MEXICO
COVERING THE GULF W OF 87W. AN UPPER TROUGH IN THE W CARIBBEAN
IS PRODUCING SCATTERED SHOWERS THAT ARE ACROSS THE STRAITS OF
FLORIDA S OF 24N E OF 87W. OTHERWISE THE GULF GULF REMAINS
RATHER CLEAR TONIGHT.

CARIBBEAN SEA...
NARROW UPPER TROUGH EXTENDS FROM AN UPPER LOW JUST N OF E CUBA
WSW ALONG 18N82W TO THE GULF OF HONDURAS AND CENTRAL AMERICA.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE OVER CUBA AND THE
YUCATAN CHANNEL N OF 20N. AN UPPER HIGH IS LOCATED OVER SOUTH
AMERICA WITH A RIDGE EXTENDING W TO INLAND OVER NICARAGUA
COVERING THE CENTRAL CARIBBEAN. AT THE NORTHERN EDGE OF THIS
UPPER RIDGE ARE SCATTERED SHOWERS WITHIN 90 NM OF LINE FROM
HAITI TO NE HONDURAS. AN UPPER RIDGE ANCHORED IN THE CENTRAL
ATLC IS ADVECTING DRY AIR OVER THE E CARIBBEAN E OF 70W.

ATLANTIC OCEAN...
BROAD DEEP LAYERED TROUGH THAT COVERS THE E US AND THE NE GULF
EXTENDS INTO THE W ATLC N OF 26N W OF 75W AND IS ANCHORED BY AN
UPPER LOW MOVING OFF THE NE US COAST WITH THE ASSOCIATED FRONTAL
BOUNDARY EXTENDING INTO THE W ATLC FROM A 1011 MB LOW N OF THE
REGION THROUGH 32N73W TO THE FLORIDA PENINSULA BETWEEN MIAMI AND
FORT LAUDERDALE. SCATTERED SHOWERS/THUNDERSTORMS ARE FROM THE
FRONT N TO DAYTONA BEACH W OF 78W. NARROW UPPER TROUGH EXTENDS
FROM 28N65W TO AN UPPER LOW BETWEEN THE BAHAMAS AND E CUBA NEAR
22N75W CONTINUING INTO THE W CARIBBEAN. SURFACE TROUGH EXTENDS
FROM 30N67W TO THE CENTRAL BAHAMAS NEAR 25N76W GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 90/120 NM OF THE
SURFACE TROUGH. BROAD UPPER RIDGE COVERS THE W/CENTRAL ATLC
ANCHORED NEAR 23N58W COVERING THE AREA S OF 27N FROM 50W-70W.
TROPICAL MOISTURE IS BEING DRAWN N OF HISPANIOLA TO GENERATE AN
AREA OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 120 NM
OF LINE 25N66W TO OVER HISPANIOLA NEAR 19N71W. GORDON REMAINS N
OF THIS UPPER RIDGE. AN UPPER TROUGH IS TO THE E OF GORDON N OF
25N FROM 28W-43W BUT IS A RATHER BENIGN FEATURE AND NOT
PRODUCING ANY SHOWER ACTIVITY. AN UPPER HIGH ASSOCIATED WITH
TROPICAL STORM HELENE COVERS THE SE TROPICAL ATLC WITH AN UPPER
LOW TO THE E CENTERED N OF THE CAPE VERDE ISLANDS NEAR 21N24W
COVERING THE FROM 15N-24N BETWEEN 20W-29W. THE SUBTROPICAL RIDGE
IS ONCE AGAIN SPREADING W OVER THE ATLC IN SPITE OF THE PRESENCE
OF HURRICANE GORDON. AN AREA OF AFRICAN DUST COVERS THE W
TROPICAL ATLC AND E CARIBBEAN S OF 23N FROM 50W-70W.

$$
WALLACE




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