[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 172249
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON SEP 17 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2215 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 19W/20W S OF 16N MOVING W NEAR 10 KT. MID
LEVEL INVERTED-V CURVATURE WITH ANY SHOWER ACTIVITY EMBEDDED
WITHIN THE ITCZ.

TROPICAL WAVE IS ALONG 43W/44W S OF 20N MOVING W NEAR 10 KT.
VERY BROAD MID LEVEL INVERTED-V CURVATURE COVERING THE AREA FROM
38W-54W. CLUSTERS OF CONVECTION ARE EMBEDDED WITHIN THE ITCZ.

TROPICAL WAVE IS ALONG 76W/77W S OF 20W MOVING W 10-15 KT. LOW
LEVEL INVERTED-V CURVATURE IS OBSERVED ALTHOUGH THE CENTRAL
CARIBBEAN IS UNDER DRY CONDITIONS.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N15W 5N28W 12N46W 7N60W. CLUSTERS
OF SCATTERED/NUMEROUS STRONG COVINGTON ARE INLAND AND MOVING
WITHIN 75 NM ALONG THE COAST OF W AFRICA FROM 10N-17N. CLUSTERS
OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE WITHIN
250/300 NM OF THE ITCZ AXIS FROM 17W-36W AND FROM 40W-55W.

DISCUSSION...

GULF OF MEXICO...
AN ELONGATED UPPER LOW IS INLAND OVER MEXICO AND COVERS THE GULF
S OF 26N W OF 92W. AN UPPER RIDGE EXTENDS FROM THE YUCATAN
PENINSULA NW TO THE LOUISIANA/TEXAS BORDER COVERING THE AREA
WITHIN 200 NM OF THE RIDGE AXIS. A DEEP LAYERED UPPER TROUGH IS
OVER THE E US INTO THE W ATLC DIPPING S OVER THE E GULF N OF 25N
E OF 85W EXTENDING A DISSIPATING FRONT FROM A WEAK 1016 MB LOW
ALONG THE E COAST OF FLORIDA NEAR DAYTONA BEACH TO NEAR 25N87W
AND A REMNANT SURFACE TROUGH OVER THE W GULF FROM 24N94W ACROSS
BROWNSVILLE TEXAS TO JUST E OF LAREDO GENERATING SCATTERED
SHOWERS/THUNDERSTORMS OVER THE S FLORIDA PENINSULA S OF OF LAKE
OKEECHOBEE TO THE UPPER KEYS. DIFFLUENCE BETWEEN ALL OF THESE
UPPER LEVEL FEATURES IS GENERATING CLUSTERS OF SCATTERED SHOWERS
AND WIDELY ISOLATED THUNDERSTORMS ACROSS THE GULF S OF 28N WHILE
THE N GULF COAST IS ENJOYING CLEAR SKIES THIS EVENING.

CARIBBEAN SEA...
AN UPPER HIGH OVER THE YUCATAN PENINSULA COVERS THE NW CARIBBEAN
N OF 16N W OF 80W. AN UPPER LOW DOMINATES MOST OF THE W
CARIBBEAN CENTERED IN THE MONA PASSAGE NEAR 19N75W EXTENDING AN
UPPER TROUGH SW TO CENTRAL AMERICA NEAR THE PANAMA/COAST RICA
BORDER. DIFFLUENCE BETWEEN THIS UPPER HIGH AND THE BROAD UPPER
LOW IN THE CARIBBEAN IS GENERATING CLUSTERS OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS N OF 15N W OF 67W BUT MAINLY OVER
THE ISLANDS OF THE GREATER ANTILLES AND JAMAICA MOVING SOUTHWARD
OVER THE COASTAL WATERS. AN UPPER RIDGE DOMINATES THE E
CARIBBEAN EXTENDING FROM VENEZUELA NEAR 10N66W N TO OVER THE
VIRGIN ISLANDS ADVECTING TROPICAL MOISTURE ACROSS THE CENTRAL
CARIBBEAN. THE AREA E OF 67W IS MOSTLY UNDER DRY CONDITIONS WITH
THE EXCEPTION SOME OF THE LEEWARD ISLANDS WHERE ACTIVITY IS
ROUGHLY ASSOCIATED WITH THE REMNANTS OF INGRID.

ATLANTIC OCEAN...
AN UPPER TROUGH THAT COVERS THE E US AND THE E GULF OF MEXICO
EXTENDS INTO THE W ATLC N OF 26N W OF 73W WITH AN ASSOCIATED
STATIONARY FRONT ENTERING THE REGION NEAR 32N72W TO A WEAK 1016
MB LOW ALONG THE E COAST OF FLORIDA NEAR DAYTONA BEACH. AN UPPER
RIDGE EXTENDS FROM THE BAHAMA ISLANDS NEAR 24N77W NE TO BEYOND
32N67W. DIFFLUENCE BETWEEN THESE UPPER LEVEL FEATURES IS
GENERATING CLUSTERS OF SCATTERED SHOWERS/THUNDERSTORMS OVER MOST
OF THE W ATLC W OF 69W. AN UPPER TROUGH IS IN THE CENTRAL/W ATLC
N OF 23N FROM 52W-67W WITH AN EMBEDDED UPPER LOW NEAR 26N59W. A
SURFACE TROUGH ASSOCIATED WITH THIS UPPER TROUGH EXTENDS FROM
30N50W ALONG 28N57W TO NEAR 23N62W. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION COVERS AN AREA E OF THE SURFACE TROUGH WITHIN
120 NM OF LINE FROM 26N54W TO 21N59W. A SMALL DEEP LAYERED LOW
IS OVER THE E/CENTRAL ATLC WITH THE UPPER LOW NEAR 32N34W AND A
PAIR OF 1018 MB SURFACE LOWS NEAR 34N39W AND 32N36W WITH A
SURFACE TROUGH EXTENDING FROM THE E SURFACE LOW ALONG 30N35W TO
26N41W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE N OF 30N
FROM 31W-36W. THE REMAINDER OF THE ATLC FROM 20N-32N IS MOSTLY
WESTERLY ZONAL FLOW. THE REMNANTS OF INGRID IS A 1010 MB SURFACE
LOW JUST E OF THE LEEWARD ISLANDS NEAR 18N61W WITH SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS TO THE E FROM 15N-19N BETWEEN
58W-61W WITH SOME ISOLATED SHOWERS MOVING ACROSS THE LEEWARD
ISLANDS. AN UPPER HIGH IS IN THE W TROPICAL ATLC NEAR 13N45W
COVERING THE AREA S OF 19N FROM 36W-55W WITH THE TYPICAL E/W
UPPER RIDGE COVERING THE REMAINDER OF THE TROPICAL; ATLC WITH
THE RIDGE AXIS ALONG 18N E OF 30W.

$$
WALLACE


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