[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT AUG 20 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA... GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND 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 1200 UTC SURFACE ANALYSIS AND
SATELLITE IMAGERY THROUGH 1715 UTC.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 17W/18W SOUTH OF 23N MOVING WEST 10 TO 15 KT.
IT APPEARS THAT A SURGE OF DUST IS EAST OF AN ARC OF CLOUDS
ALONG THE LINE 28N13W 25N20W 20N23W 14N20W. A 1011 MB LOW
PRESSURE CENTER IS NEAR 18N ALONG THE WAVE. STRONG SHOWERS AND
THUNDERSTORMS ARE SOUTH OF THE LOW CENTER FROM 13N TO 14N
BETWEEN 17W AND 18W...AND MORE SOUTHWEST OF THE CENTER FROM 10N
TO 13N BETWEEN 19W AND 24W.

A SURFACE TROUGH IS ALONG 30W/31W FROM 11N TO 19N MOVING WEST
10 KT. THIS TROUGH APPEARS TO SHOW UP IN THE CYCLONIC MOVEMENTS
OF NEARBY LOW CLOUDS. ISOLATED MODERATE SHOWERS...WHETHER OR NOT
ACTUALLY CAUSED BY THE TROUGH...ARE FOUND FROM 12N TO 14N
BETWEEN 25W AND 30W.

CARIBBEAN SEA TROPICAL WAVE ALONG 66W/67W SOUTH OF 18N MOVING
WEST 10 TO 15 KT. IT IS POSSIBLE NOW...AFTER LOOKING AT SOME
LATER VISIBLE SATELLITE IMAGERY...THAT THIS WAVE EXTENDS MORE
TO THE NORTH INTO THE ATLANTIC OCEAN NEAR 25N. MIDDLE TO UPPER
LEVEL CYCLONIC FLOW WITH AN EASTERN CARIBBEAN SEA INVERTED
TROUGH IS CONFINED TO THE AREA SOUTH OF 17N/18N BETWEEN 60W AND
72W. WIDELY SCATTERED TO SCATTERED MODERATE/ISOLATED STRONG
SHOWERS AND THUNDERSTORMS COVER THE AREA FROM 15N TO 22N BETWEEN
60W AND 72W. MOST OF THE PRECIPITATION SEEMS TO BE ON TOP OF
PUERTO RICO AND TO THE NORTH AND SOUTH OF PUERTO RICO.

A SURFACE TROUGH ALONG 71W/72W FROM 17N TO 25N IS MOVING WEST
10 KT. THE SHOWER/THUNDERSTORM ACTIVITY IS PRETTY SPOTTY...
ISOLATED AT BEST...FROM 18N TO 23N BETWEEN THE MONA PASSAGE
AND THE WINDWARD PASSAGE. SOME OF THE PRECIPITATION FROM THE
ACTIVITY NEAR PUERTO RICO MAY BE CLOSE THAT WHICH IS RELATED
TO THE 66W/67W TROPICAL WAVE.

A TROPICAL WAVE RUNS FROM THE SOUTHWESTERN GULF OF MEXICO...TO
JUST WEST OF THE YUCATAN PENINSULA INTO SOUTHWESTERN GUATEMALA
AND INTO THE EASTERN PACIFIC OCEAN ALONG 92W SOUTH OF 20N...
MOVING WEST 10 TO 15 KT. SHOWERS AND THUNDERSTORMS...ALTHOUGH
DISSIPATING AT TIMES...IN THE SOUTHWESTERN CORNER OF THE GULF
OF MEXICO FROM 18N TO 23N BETWEEN 93W AND 99W...ARE IN AN AREA
OF UPPER LEVEL DIFFLUENT FLOW...IN THE MIDDLE OF AN UPPER LEVEL
RIDGE IN THE SOUTHWESTERN GULF OF MEXICO AND BROAD MIDDLE TO
UPPER LEVEL ANTICYCLONIC FLOW ACROSS MUCH OF THE REST OF THE
GULF OF MEXICO WATERS.

...THE ITCZ...

ITCZ 14N19W 10N30W 10N38W...10N42W 9N50W 10N60W. WIDELY
SCATTERED MODERATE TO ISOLATED STRONG SHOWERS AND
THUNDERSTORMS...SOME AREAS WITH WARMING CLOUD TOP TEMPERATURES
AND DISSIPATING CONVECTIVE ACTIVITY WHILE SOME NEW CLUSTERS
ARE DEVELOPING...FROM 6N TO 10N BETWEEN 20W AND 50W.

...DISCUSSION...

THE GULF OF MEXICO...
MIDDLE TO UPPER LEVEL ANTICYCLONIC WIND FLOW SPANS THE OPEN
WATERS OF THE GULF OF MEXICO...EXCEPT FOR THE SOUTHWESTERN
CORNER OF THE AREA. A TROPICAL WAVE IS MOVING THROUGH THE
SOUTHWESTERN CORNER OF THE AREA ALONG 92W. SHOWERS AND
THUNDERSTORMS ARE IN THE SOUTHWESTERN CORNER...IN AN AREA OF
BROAD MIDDLE TO UPPER LEVEL DIFFLUENT WIND FLOW. THE DIFFLUENCE
COMES ABOUT BECAUSE OF THE BROAD FLOW OVER MUCH OF THE GULF
WATERS AND AN UPPER LEVEL RIDGE FROM THE ISTHMUS OF TEHUANTEPEC
NORTHWARD. BROAD SURFACE ANTICYCLONIC WIND FLOW. ISOLATED
SHOWERS ARE POPPING UP...MOSTLY NORTH OF 22N. THE SURFACE
PRESSURE GRADIENT IS WEAK. THE 1016 MB CUTS RIGHT THROUGH THE
GULF FROM WESTERN CUBA TO THE LOWER TEXAS COAST. THE 1014 MB
ISOBAR RUNS FROM THE NORTHEASTERN YUCATAN PENINSULA TO JUST
SOUTH OF TAMPICO MEXICO.

THE CARIBBEAN SEA...
CARIBBEAN SEA TROPICAL WAVE ALONG 66W/67W SOUTH OF 18N MOVING
WEST 10 TO 15 KT. IT IS POSSIBLE NOW...AFTER LOOKING AT SOME
LATER VISIBLE SATELLITE IMAGERY...THAT THIS WAVE EXTENDS MORE
TO THE NORTH INTO THE ATLANTIC OCEAN NEAR 25N. MIDDLE TO UPPER
LEVEL CYCLONIC FLOW WITH AN EASTERN CARIBBEAN SEA INVERTED
TROUGH IS CONFINED TO THE AREA SOUTH OF 17N/18N BETWEEN 60W AND
72W. WIDELY SCATTERED TO SCATTERED MODERATE/ISOLATED STRONG
SHOWERS AND THUNDERSTORMS COVER THE AREA FROM 15N TO 22N BETWEEN
60W AND 72W. MOST OF THE PRECIPITATION SEEMS TO BE ON TOP OF
PUERTO RICO AND TO THE NORTH AND SOUTH OF PUERTO RICO. A MIDDLE
TO UPPER LEVEL INVERTED TROUGH RUNS FROM THE YUCATAN PENINSULA
TO WESTERN HONDURAS. AN UPPER LEVEL RIDGE IS ON TOP OF THIS
FEATURE...AS EVIDENCED BY THE HIGH CLOUDS MOVING SOUTHEASTWARD
OVER THE WATERS NORTH OF EASTERN HONDURAS. SHOWERS AND
THUNDERSTORMS ARE IN GENERAL NORTH OF 14N.

THE ATLANTIC OCEAN...
BROAD MIDDLE TO UPPER LEVEL ANTICYCLONIC FLOW CURVES FROM THE
AREA NORTH OF 32N70W SOUTHWESTWARD TO THE BAHAMAS AND FLORIDA.
MIDDLE TO UPPER LEVEL CYCLONIC SWIRLS ARE OVER THE SOUTHERN
BAHAMAS. AN UPPER LEVEL RIDGE CURVES NORTHEASTWARD FROM THE AREA
JUST NORTH OF PUERTO RICO AND THE AREA OF THE CARIBBEAN SEA
INVERTED TROUGH REACHING 27N60W. A MIDDLE TO UPPER LEVEL
CYCLONIC CIRCULATION CENTER IS NEAR 28N44W. IT IS SURROUNDED BY
A GREAT AMOUNT OF MIDDLE TO UPPER LEVEL DRY AIR. CYCLONIC FLOW
AROUND THIS CENTER COVERS THE ATLANTIC WATERS FROM 20N TO 35N
BETWEEN 40W AND 52W. MIDDLE TO UPPER LEVEL DRY AIR COVERS THE
ATLANTIC WATERS IN GENERAL NORTH OF 10N BETWEEN 30W AND 60W.

$$
MT


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