[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 181038
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED JUL 18 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS SLIGHTLY TITLED ALONG 20N28W THROUGH A 1011 MB
LOW NEAR 15N30W 9N31W MOVING W NEAR 20 KT. BROAD WELL DEFINED
CIRCULATION ASSOCIATED WITH THE SURFACE LOW COVERING THE AREA
FROM 11N-22N BETWEEN 27W-37W. NO ASSOCIATED DEEP CONVECTION.

TROPICAL WAVE IS SLIGHTLY TILTED ALONG 18N54W 10N57W 3N57W
MOVING W NEAR 20 KT. BROAD WAVE WITH LOW/MID LEVEL INVERTED-V
CURVATURE COVERING THE AREA FROM 50W-65W. SCATTERED MODERATE/
ISOLATED STRONG CONVECTION IS WITHIN 90/120 NM OF LINE FROM
15N52W TO THE COAST OF SOUTH AMERICA NEAR 11N63W INCLUDING THE
WINDWARD ISLANDS...TRINIDAD AND TOBAGO.

TROPICAL WAVE IS ALONG 84W S OF 19N MOVING W NEAR 20 KT. WAVE IS
MOSTLY INLAND OVER CENTRAL AMERICA JUST TO THE E OF AN UPPER
RIDGE ENHANCING SCATTERED MODERATE/ISOLATED STRONG CONVECTION
FROM 14N-17N BETWEEN 82W-85W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 14N15W 15N22W 10N27W 7N41W 12N56W
9N63W. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 120/150 NM
OF THE AXIS FROM 43W-49W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 60/75 NM OF THE AXIS FROM 28W-36W AND
WITHIN 120 NM OF LINE FROM 10N49W TO 11N54W. CLUSTERS OF SIMILAR
CONVECTION ARE FROM 6N-10N BETWEEN 50W-61W AND WITHIN 120 NM
ALONG THE COAST OF AFRICA FROM 7N-10N.

...DISCUSSION...
GULF OF MEXICO...
BROAD UPPER LEVEL LOW IS CENTERED OVER N/CENTRAL MEXICO COVERING
TEXAS AND MEXICO N OF 21N. AN UPPER LEVEL RIDGE EXTENDS FROM S
MEXICO ACROSS THE BAY OF CAMPECHE AND THE W GULF TO THE N GULF
COAST NEAR 29N95W ENHANCING SCATTERED SHOWERS/THUNDERSTORMS S OF
28N W OF 88W AND INDUCING A SURFACE TROUGH THAT EXTENDS ROUGHLY
E/W FROM 25N88W ALONG 24N94W TO 22N98W. ANOTHER UPPER RIDGE
EXTENDS FROM AN UPPER HIGH OFF THE E COAST OF THE FLORIDA
PENINSULA TO OVER THE E GULF ENHANCING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS OVER S OF 28N E OF 88W. OTHERWISE A
SURFACE RIDGE IS BEGINNING TO WEAKEN AND EXTENDS ALONG 29W/30N
FROM THE W ATLC TO TEXAS.

CARIBBEAN SEA...
THE UPPER RIDGE OVER THE W GULF OF MEXICO EXTENDS OVER THE FAR W
CARIBBEAN W OF 87W. A CUT-OFF UPPER LOW REMAINS CENTERED OVER
THE CAYMAN ISLANDS NEAR 19N80W COVERING THE AREA N OF 15N FROM
73W-85W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF
17N FROM 80W-85W. AN UPPER RIDGE EXTENDS FROM OVER COLOMBIA/
PANAMA BORDER NW TO CENTRAL AMERICA NEAR 14N83W. THIS UPPER
RIDGE COMBINED WITH THE ITCZ AXIS EXTENDING ACROSS S PANAMA AND
COSTA RICA ARE GENERATING SCATTERED SHOWERS/THUNDERSTORMS S OF
11N E OF 82W TO INLAND OVER COLOMBIA AND PANAMA. WEAK UPPER HIGH
IS IN THE W TROPICAL ATLC E OF THE LEEWARD ISLANDS EXTENDING A
RIDGE AXIS E ACROSS THE LEEWARD ISLANDS TO 15N72W AND IS BEING
ECLIPSED BY THE TROPICAL WAVE E OF THE LESSER ANTILLES. DRY
STABLE AIR COVERS THE E CARIBBEAN E OF 80W EXCEPT IN THE REGION
OF THE WINDWARD ISLANDS WHERE THERE IS CONVECTION ASSOCIATED
WITH THE TROPICAL WAVE. MODERATE/STRONG EASTERLY TRADE WINDS
CONTINUE ACROSS THE CARIBBEAN.

ATLANTIC OCEAN...
AN UPPER HIGH OFF THE E COAST OF THE FLORIDA PENINSULA NEAR
28N79W AND COVERS THE W ATLC N OF 25N W OF 70W. THE CUT-OFF
UPPER LOW OVER THE CAYMAN ISLANDS COVERS THE SW ATLC S OF 25N W
OF 74W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF
30N W OF 78W ACROSS S FLORIDA INTO THE E GULF OF MEXICO. AN
ELONGATED UPPER LOW IS NEAR 28N65W COVERING THE AREA N OF 23N
FROM 60W-68W WITH A WEAK SURFACE TROUGH EXTENDING FROM 32N61W TO
THE MONA PASSAGE GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS WITHIN 120/150 NM OF LINE FROM 19N67W 25N63W TO
32N61W. WEAK UPPER HIGH IS IN THE W TROPICAL ATLC E OF THE
LEEWARD ISLANDS NEAR 18N61W EXTENDING A RIDGE AXIS E INTO THE
CARIBBEAN AND NE TO 27N58W ENHANCING THE ABOVE SHOWER/
THUNDERSTORM ACTIVITY. WEAK NARROW UPPER TROUGH EXTENDS INTO THE
N/CENTRAL ATLC ALONG 32N33W TO 23N45W BUT THE ASSOCIATED
LOW/FRONTAL BOUNDARY ARE N OF THE REGION. ANOTHER UPPER RIDGE
EXTENDS OFF THE COAST OF AFRICA OVER THE E ATLC E OF 30W. THE
FIRST VISIBLE IMAGES OF THE DAY SHOW A LARGE SURGE OF AFRICAN
DUST CONTINUING OVER THE E ATLC S OF A LINE FROM THE STRAIT OF
GIBRALTAR 35N12W 30N22W 23N50W WITH SOME CLEARING S OF 14N E OF
26W. THERE IS A TROPICAL WAVE/LOW IS EMBEDDED WITHIN THIS DUST.
THE REMAINDER OF THE ATLC CONTINUES TO BE DOMINATED BY A SURFACE
RIDGE ANCHORED BY A 1029 MB HIGH CENTERED N OF THE REGION NEAR
36N50W AND EXTENDS TO OVER THE N GULF OF MEXICO.

$$
WALLACE





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