[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211032
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT JUL 21 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...
A TROPICAL WAVE MOVED OFF THE COAST OF AFRICA ALONG 18W S OF 17N
MOVING W 15 KT. WELL DEFINED MID LEVEL CYCLONIC ROTATION IS
ALONG THE WAVE AXIS NEAR 13N WITH NO EVIDENCE OF A SURFACE LOW
AT THIS TIME. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
FROM 10N-13N BETWEEN THE COAST OF AFRICA AND 21W.

TROPICAL WAVE IS ALONG 50W-51W S OF 22N MOVING W 15 KT. BROAD
WAVE LOW LEVEL INVERTED-V CURVATURE COVERING THE AREA FROM
45N-60N. NO ASSOCIATED SHOWERS/CONVECTION.

TROPICAL WAVE IN THE E CARIBBEAN IS ALONG 73W/74W S OF 18N
MOVING W 15 KT. WAVE HAS WEAK LOW AMPLITUDE INVERTED-V CURVATURE
OVER THE CENTRAL CARIBBEAN. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE N OF 17N TO OVER HISPANIOLA FROM 72W-76W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N20W 6N30W 13N49W 9N62W. CLUSTERS
OF SCATTERED MODERATE CONVECTION ARE FROM 5N-10N BETWEEN
17W-34W.

...DISCUSSION...
GULF OF MEXICO...
BROAD UPPER LEVEL HIGH IS INLAND OVER N/CENTRAL MEXICO WITH THE
UPPER RIDGE COVERING THE GULF W OF 87W WITH THE ASSOCIATED DEEP
CONVECTION REMAINING INLAND OVER TEXAS AND MEXICO. DEEP LAYERED
TROUGH IS OVER THE N GULF COAST N OF 30N ACROSS THE SE US WITH A
WEAKENING SHORTWAVE UPPER TROUGH EXTENDS FROM THE W ATLC ACROSS
NE FLORIDA INTO THE E GULF TO NEAR 27N84W AND A SURFACE TROUGH
THAT EXTENDS FROM THE W ATLC ACROSS FLORIDA S OF JACKSONVILLE TO
28N84W. THE DEEP LAYERED TROUGH CONTINUES TO BRING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS S TO WITHIN 90 NM ALONG THE N
GULF COAST FROM THE MISSISSIPPI DELTA OF LOUISIANA TO ACROSS THE
FLORIDA PANHANDLE. WEAKENING CUT-OFF UPPER LOW THAT IS NW OF THE
CAYMAN ISLANDS CLIPS THE GULF OF THE FLORIDA STRAITS. THIS
COMBINED WITH THE SHORTWAVE TROUGH ABOVE CONTINUES TO GENERATE
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 28N E OF 85W OVER
THE FLORIDA STRAITS. OTHERWISE A WEAK SURFACE RIDGE COVERS THE
NW GULF WITH A 1018 MB HIGH OFF SW LOUISIANA NEAR 28N91W.

CARIBBEAN SEA...
WEAKENING CUT-OFF UPPER LOW REMAINS CENTERED NW OF THE CAYMAN
ISLANDS NEAR 21N82W COVERING THE AREA N OF 18N FROM 78W TO THE
YUCATAN CHANNEL GENERATING SCATTERED SHOWERS/THUNDERSTORMS
WITHIN 120 NM ALONG THE COAST OF CUBA FROM 78W-84W. BROAD UPPER
HIGH ANCHORED JUST E OF THE LESSER ANTILLES EXTENDS A RIDGE AXIS
E ACROSS THE REMAINDER OF THE CARIBBEAN ENHANCING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS N OF 17N FROM 74W-87W. THE ITCZ
AXIS IN THE E PACIFIC REGION EXTENDS FROM COLOMBIA ACROSS S
PANAMA GENERATING CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION S OF 12N FROM 75W-78W TO INLAND OVER COLOMBIA AND E
PANAMA. MODERATE EASTERLY TRADE WINDS CONTINUING ACROSS THE
S/CENTRAL CARIBBEAN.

ATLANTIC OCEAN...
DEEP LAYERED TROUGH IS INLAND OVER THE E US WITH A SHORTWAVE
UPPER TROUGH EXTENDING THROUGH 32N76W ACROSS NE FLORIDA AND A
SURFACE TROUGH EXTENDING THROUGH 32N78W ACROSS FLORIDA S OF
JACKSONVILLE WHILE THE FRONTAL BOUNDARY REMAINS N OF THE REGION.
THIS IS GENERATING SCATTERED SHOWERS/THUNDERSTORMS WITHIN 60/75
NM OF A LINE FROM 28N80W TO BEYOND 32N76W. CUT-OFF UPPER LOW NW
OF THE CAYMAN ISLANDS CLIPS THE FLORIDA STRAITS PRODUCING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 26N W OF 79W. AN
UPPER LOW REMAINS IN THE W/CENTRAL ATLC NEAR 27N68W COVERING THE
AREA N OF 23N FROM 63W-73W WITH A SURFACE TROUGH EXTENDING FROM
THE N COAST OF HISPANIOLA NEAR 20N70W TO NEAR 26N68W GENERATING
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN
120 NM OF LINE FROM 27N60W 23N63W TO 23N70W AND A BROADER AREA
OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 20N-31N BETWEEN
59W-69W. UPPER HIGH JUST E OF THE LESSER ANTILLES NEAR 18N60W
EXTENDS A RIDGE AXIS N TO NEAR 30N61W ENHANCING THE SHOWER
ACTIVITY/CONVECTION ASSOCIATED WITH THE CUR-OFF UPPER LOW AND
SURFACE TROUGH MENTIONED ABOVE. BENIGN UPPER LEVEL FEATURES WITH
DRY STABLE AIR DOMINATES THE REMAINDER OF THE ATLC WITH A STRONG
SURFACE RIDGE ANCHORED BY A 1035 MB HIGH CENTERED WELL N OF THE
REGION. THE FIRST VISIBLE SATELLITE IMAGES OF THE DAY SHOW AN
AREA OF AFRICAN DUST FROM 15N-30W E OF 35W.

$$
WALLACE




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