[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 201033
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI JUL 20 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
0945 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS TITLED FROM 21N40W 15N44W 7N46W MOVING W 15-20
KT. BROAD WAVE LOW LEVEL INVERTED-V CURVATURE COVERING THE AREA
FROM 38N-50N. NO ASSOCIATED SHOWERS/CONVECTION.

TROPICAL WAVE IN THE E CARIBBEAN HAS BEGUN TO SPLIT WITH THE N
PORTION MOVING SLOWER NW THAN THE S PORTION MOVING W. WAVE IS
ALONG 67W/68W S OF 17N MOVING W 15 KT. THE N PORTION OF THIS
WAVE HAS SOME POTENTIAL FOR FURTHER DEVELOPMENT. SEE BELOW.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 14N-18N
BETWEEN 66W-71W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 9N12W 6N21W 13N46W 11N61W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 150/200 NM OF THE
AXIS E OF 18W TO JUST INLAND OVER SIERRA LEONE AND GUINEA
AFRICA. SIMILAR CONVECTION IS WITHIN A 75 NM RADIUS OF 9N20W.

...DISCUSSION...
GULF OF MEXICO...
UPPER LEVEL HIGH IS INLAND OVER NE MEXICO WITH THE UPPER RIDGE
COVERING THE GULF W OF 87W ENHANCING LOW LEVEL SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS WITHIN 120 NM ALONG THE COAST OF
TEXAS AND LOUISIANA. SHORTWAVE UPPER TROUGH EXTENDS FROM JUST
OFF THE E COAST OF THE CAROLINAS OVER NE FLORIDA INTO THE FAR NE
GULF BRINGING SHOWER ACTIVITY TO THE W ATLC. THE CUT-OFF UPPER
LOW THAT IS JUST W OF THE CAYMAN ISLANDS COVERS THE GULF S OF
25N E OF 87W INTO THE W ATLC GENERATING ISOLATED SHOWERS/
THUNDERSTORMS S OF 26N E OF 84W. OTHERWISE A WEAK SURFACE RIDGE
REMAINS ACROSS THE GULF FROM THE W ATLC WITH A 1018 MB HIGH OVER
THE NE GULF NEAR 28N86W.

CARIBBEAN SEA...
AN ELONGATED CUT-OFF UPPER LOW REMAINS CENTERED JUST E OF THE
CAYMAN ISLANDS NEAR 20N83W COVERING THE AREA N OF 17N FROM 76W
TO THE YUCATAN PENINSULA GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS FROM N OF 17N FROM 75W-84W WITH THE BULK OF THE
ACTIVITY ALONG THE COAST OF CUBA FROM 80W-83W. BROAD UPPER HIGH
IS CENTERED OVER THE FAR NE CARIBBEAN NEAR 17N64W COVERING THE E
CARIBBEAN E OF 75W AND EXTENDS INTO THE W TROPICAL ATLC AND
CENTRAL ATLC. THE ITCZ AXIS IN THE E PACIFIC REGION EXTENDS
ACROSS PANAMA AND COSTA RICA GENERATING SCATTERED MODERATE/
ISOLATED STRONG CONVECTION S OF 10N FROM COLOMBIA TO COSTA RICA.
MODERATE/STRONG EASTERLY TRADE WINDS CONTINUE ACROSS THE
CARIBBEAN S OF 17N.

ATLANTIC OCEAN...
THE MAIN AREA OF FOCUS THIS MORNING THAT WAS THE N PORTION OF
THE CARIBBEAN TROPICAL WAVE AND IS NOW A SURFACE TROUGH THAT
EXTENDS FROM THE MONA PASSAGE TO NEAR 25N63W. THIS BROAD AREA OF
LOW LEVEL CYCLONIC TURNING IS PRODUCING HEAVY RAINS WITH
EMBEDDED THUNDERSTORMS E OF THE TROUGH AXIS FROM 16N-23N BETWEEN
69W-65W INCLUDING THE LEEWARD AND VIRGIN ISLANDS. THE RAINS HAVE
NOT BEGUN IN ERNEST OVER PUERTO RICO AS OF YET BUT WILL BE
MOVING OVER THE ISLAND LATER TODAY. OTHERWISE...SHORTWAVE UPPER
TROUGH EXTENDS FROM JUST OFF THE E COAST OF THE CAROLINAS ACROSS
NE FLORIDA AND EXTENDS OVER THE W ATLC N OF 27N W OF 76W
GENERATING SCATTERED SHOWERS/THUNDERSTORMS WITHIN 200 NM ALONG
THE E US COAST N OF 30N. CUT-OFF UPPER LOW JUST E OF THE CAYMAN
ISLANDS COVERS THE SW ATLC S OF 25N W OF 76W BUT IS ONLY
PRODUCING WIDELY ISOLATED SHOWERS BETWEEN CUBA AND THE BAHAMA
ISLANDS. AN UPPER LOW REMAINS IN THE NW ATLC NEAR 26N67W
COVERING THE AREA N OF 23N FROM 63W-73W WITH A WEAKENING SURFACE
TROUGH EXTENDING FROM 31N64W TO 26N66W. THE UPPER LOW IS BEING
OVERRUN BY THE UPPER RIDGE TO THE S AND IS DRAWING UPPER LEVEL
MOISTURE N AWAY FROM THE TROUGH THAT EXTENDS FROM THE MONA
PASSAGE TO 24N63W. THE UPPER HIGH IN THE NE CARIBBEAN EXTENDS A
RIDGE AXIS NE ACROSS THE LEEWARD/VIRGIN ISLANDS TO NEAR 26N59W
ENHANCING THE HEAVY RAINS AND THUNDERSTORMS ASSOCIATED WITH THE
SURFACE TROUGH MENTIONED ABOVE. A CUT-OFF UPPER LOW IS CENTERED
IN THE CENTRAL ATLC NEAR 29N50W COVERING THE AREA N OF 16N FROM
40W-56W WITH A VERY NARROW UPPER RIDGE BETWEEN THIS UPPER LOW
AND THE UPPER LOW CENTERED NEAR 26N67W ENHANCING SCATTERED
SHOWERS FROM 25N-31N BETWEEN 46W-66W. UPPER RIDGE EXTENDS OFF
THE COAST OF AFRICA OVER THE E ATLC E OF 37W. THE FIRST VISIBLE
SATELLITE IMAGES OF THE DAY CONTINUE TO SHOW A LARGE AREA OF
AFRICAN DUST ALTHOUGH IT APPEARS LESS DENSE THAN YESTERDAY. THE
REMAINDER OF THE ATLC CONTINUES TO BE DOMINATED BY A SURFACE
RIDGE ANCHORED BY A 1032 MB HIGH CENTERED N OF THE REGION TO
OVER THE N GULF OF MEXICO.

$$
WALLACE





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