[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 181805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU AUG 18 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.

...SPECIAL FEATURES...

THE CENTER OF TROPICAL STORM IRENE WAS NEAR 45.0N 47.5W AT
18/1200 UTC OR ABOUT 295 MILES/475 KM EAST-SOUTHEAST OF CAPE
RACE NEWFOUNDLAND...MOVING NORTHEAST 40 KT. THE MAXIMUM
SUSTAINED WIND SPEEDS WERE 50 KT WITH GUSTS TO 60 KT.
THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 992 MB. PLEASE
SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC OR MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS.
IRENE LOSING TROPICAL CHARACTERISTICS AS IT RACES NORTHEASTWARD.
SATELLITE IMAGES AND SURFACE OBSERVATIONS INDICATE THAT IRENE IS
BECOMING EXTRATROPICAL OVER THE NORTH ATLANTIC. SCATTERED
MODERATE TO ISOLATED STRONG SHOWERS AND THUNDERSTORMS FROM 46N
TO 48N BETWEEN 42W AND 47W. THE LAST FORECAST/ADVISORY ABOUT
IRENE HAS BEEN ISSUED BY THE NATIONAL HURRICANE CENTER AT
18/1500 UTC.

1013 MB MB SURFACE LOW PRESSURE CENTER...THE REMNANT OF TROPICAL
DEPRESSION TEN...WAS NEAR 18N60W MOVING WEST-NORTHWEST 10 TO
15 KT. ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS AND FEW
THUNDERSTORMS FROM 17N TO 22N BETWEEN 58W AND 61W. ISOLATED
MODERATE SHOWERS ALSO WERE IN A LINE WHICH STRETCHES WAY TO
THE SOUTH OF THIS FEATURE...WITHIN 30 TO 40 NM ON EITHER SIDE
OF 7N59W 13N58W 18N58W. SATELLITE IMAGES AND SURFACE
OBSERVATIONS SUGGEST THAT THE SYSTEM HAS BECOME LESS ORGANIZED
AND THE LOW PRESSURE AREA LESS DEFINED. CONDITIONS STILL MAY
BECOME A LITTLE MORE FAVORABLE FOR DEVELOPMENT AS THE SYSTEM
MOVES TOWARD THE WEST-NORTHWEST AT 10 TO 15 MPH. AN AIR FORCE
RESERVE UNIT RECONNAISSANCE AIRCRAFT IS ENROUTE TO INVESTIGATE
THE AREA LATER TODAY.

AN AREA OF DISTURBED WEATHER OVER THE SOUTHWESTERN CARIBBEAN SEA
IS ASSOCIATED WITH A TROPICAL WAVE AND A WEAK SURFACE TROUGH.
THIS SYSTEM IS EXPECTED TO MOVE SLOWLY WEST-NORTHWESTWARD OVER
CENTRAL AMERICA...AND DEVELOPMENT IS NOT ANTICIPATED.

...TROPICAL WAVES...

THE MOST RECENT TROPICAL WAVE BARELY JUST HAD CROSSED 20W...NOW
ALONG 21W SOUTH OF 22N MOVING WEST 5 TO 10 KT. THERE IS SOME
DOUBT ABOUT A WAVE EVEN EXISTING ALONG 21W. IT HAS NOT BEEN
MOVING MUCH IF ANY SINCE IT WAS PUT ON THE MAP. THE DAKAR
TIMESECTION SHOWS A WHOLE CYCLONIC CIRCULATION FROM THE SURFACE
TO 800 MB FROM 14/0000 UTC TO 16/0000 UTC. NOTHING APPEARS TO
HAVE PASSED THE CAPE VERDE ISLANDS YET. ISOLATED MODERATE SHOWERS
AND POSSIBLE THUNDERSTORMS FROM 10N TO 16N BETWEEN 14W AND 24W.
THE LOW PRESSURE CENTER WHICH WAS ALONG THIS WAVE AT 18/0600 UTC
WAS NOT APPARENT AT 18/1200 UTC.

AN ATLANTIC OCEAN TROPICAL WAVE WAS ALONG 52W/53W SOUTH OF 19N
MOVING WEST 15 KT. THE DUST SEEMS TO SHOW UP THE BEST ON THE
VISIBLE SATELLITE IMAGERY SOUTH OF 23N BETWEEN 42W AND THE WAVE.

A TROPICAL WAVE IS ALONG 81W SOUTH OF 24N MOVING WEST 10 TO
15 KT. THIS WAVE IS LEFT OVER FROM THE WAVE WHICH GAVE BIRTH TO
TROPICAL DEPRESSION TEN. IT CONTINUED TO MOVE WESTWARD AND NOW
FINDS ITSELF IN THE SOUTHWESTERN CARIBBEAN SEA. MIDDLE TO UPPER
LEVEL CYCLONIC FLOW IS IN THE SOUTHWESTERN CORNER OF THE AREA...
ACCOMPANIED BY UPPER LEVEL ANTICYCLONIC FLOW. STRONG SHOWERS AND
THUNDERSTORMS FROM 18/1245 UTC AND LATER HAVE WEAKENED AS THE
CLOUD TOP TEMPERATURES HAVE BEEN WARMING. ALL THIS IS OCCURRING
SOUTH OF 15N BETWEEN 79W AND THE COAST OF CENTRAL AMERICA.

THE LAST TROPICAL WAVE IS ALONG 94W SOUTH OF 22N MOVING WEST
10 TO 15 KT. THIS WAVE RUNS FROM THE SOUTHWESTERN GULF OF MEXICO
ACROSS THE ISTHMUS OF TEHUANTEPEC INTO THE EASTERN PACIFIC OCEAN.
NO THUNDERSTORM ACTIVITY IS DIRECTLY RELATED TO THIS WAVE.

...THE ITCZ...

ITCZ 13N23W 10N30W 9N40W 9N50W 8N55W 10N65W. WIDELY SCATTERED
TO SCATTERED MODERATE/ISOLATED STRONG SHOWERS AND THUNDERSTORMS
FROM 6N TO 10N BETWEEN 23W AND 42W.

...DISCUSSION...

THE GULF OF MEXICO...
ONE MIDDLE TO UPPER LEVEL TROUGH GOES FROM NORTH CENTRAL MEXICO
TOWARD THE SOUTHERN PART OF BAJA CALIFORNIA INTO THE EASTERN
PACIFIC OCEAN NEAR 21N113W. A MIDDLE TO UPPER LEVEL CYCLONIC
CIRCULATION CENTER WAS NEAR 27N94W. CYCLONIC FLOW COVERS THE
AREA WEST OF 90W. SCATTERED MODERATE TO ISOLATED STRONG SHOWERS
AND THUNDERSTORMS ARE WITHIN 120 NM OF THE CYCLONIC CENTER FROM
EAST THROUGH SOUTH. UPPER LEVEL EASTERLY WIND FLOW FILLS UP THE
REST OF THE GULF WATERS. A SURFACE RIDGE RUNS FROM THE
SOUTHWESTERN NORTH ATLANTIC OCEAN JUST NORTH OF THE BAHAMAS
ACROSS FLORIDA INTO THE NORTH CENTRAL GULF.

THE CARIBBEAN SEA...
ONE BIG EAST-NORTHEAST TO WEST-SOUTHWEST ORIENTED TROUGH
STRETCHES
FROM THE SOUTHERN BAHAMAS ACROSS SOUTHEAST CUBA TOWARD THE GULF
OF HONDURAS. ONE AREA OF UPPER LEVEL ANTICYCLONIC FLOW COVERS
THE SOUTHWESTERN CORNER OF THE AREA...SHARING SPACE WITH THE 81W
TROPICAL WAVE AND RELATED CLOUDS AND SHOWERS AND THUNDERSTORMS.
ANOTHER AREA OF UPPER LEVEL ANTICYCLONIC FLOW IS EAST OF 71W
SOUTH OF THE GREATER ANTILLES. WIDELY SCATTERED MODERATE TO
ISOLATED STRONG SHOWERS AND THUNDERSTORMS AND BROKEN TO OVERCAST
MULTILAYERED CLOUDS ARE NEARLY EVERYWHERE ELSE SOUTH OF 20N. THE
CONVECTIVE ACTIVITY OF COMPARATIVELY THE GREATEST INTENSITY IS
THE
STRONG SHOWERS AND THUNDERSTORMS FROM 14.5N TO 16.5N BETWEEN 72W
AND 76W...AND SOME SCATTERED STRONG SHOWERS AND THUNDERSTORMS
FROM 14N TO 16N BETWEEN 69W AND 71W.

THE ATLANTIC OCEAN...

A MIDDLE TO UPPER LEVEL TROUGH RUNS FROM AN ATLANTIC MIDDLE TO
UPPER LEVEL CYCLONIC CIRCULATION CENTER NEAR 32N43W TO 25N48W
TO A 24N64W CYCLONIC CENTER...TO THE SOUTHERN BAHAMAS. THIS
TROUGH EVENTUALLY CONTINUES FROM THE SOUTHERN BAHAMAS INTO
THE CARIBBEAN SEA TO THE GULF OF HONDURAS. THIS SURFACE LOW IS
MOVING TOWARD AN ATLANTIC MIDDLE TO UPPER LEVEL TROUGH WHICH
STRETCHES FROM 31N41W TO 27N52W TO 22N68W TOWARD THE
NORTHEASTERN NICARAGUA/EASTERN HONDURAS BORDER. A SURFACE TROUGH
RUNS FROM 30N60W TO 25N66W THROUGH THE WINDWARD PASSAGE TO
18N74W IN SOUTHWESTERN HAITI. SCATTERED MODERATE TO ISOLATED
STRONG SHOWERS AND THUNDERSTORMS ARE WITHIN 30 TO 45 NM
ON EITHER SIDE OF THIS SURFACE TROUGH. A SURFACE RIDGE PASSES
THROUGH 32N38W TO 22N47W. BROAD UPPER LEVEL ANTICYCLONIC COVERS
THE REST OF THE ATLANTIC WATERS EAST AND SOUTHEAST OF THE
ATLANTIC-TO-CARIBBEAN SEA MIDDLE TO UPPER LEVEL TROUGH. BROAD
UPPER LEVEL ANTICYCLONIC FLOW IS EAST OF 24W OVER INTERIOR
AFRICA.

$$
MT


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