[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 041805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE OCT 04 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
1745 UTC.

...SPECIAL FEATURES...

THE CENTER OF TROPICAL STORM STAN AT 04/1800 UTC IS INLAND
NEAR 18.0N 95.5W OR ABOUT 80 NM/150 KM SOUTH-SOUTHEAST OF
VERACRUZ MEXICO. STAN IS MOVING SOUTHWEST 8 KT. THE ESTIMATED
MINIMUM CENTRAL PRESSURE IS 988 MB. THE MAXIMUM SUSTAINED WIND
SPEEDS ARE 55 KT WITH GUSTS TO 65 KT. PLEASE REFER TO THE LATEST
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC
AND THE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT5/WTNT35
FOR MORE DETAILS. THE AMOUNT OF AREAL COVERAGE OF CLOUD TOPS
REACHING CLOSE TO 54000 FEET AND CLOUD TOP TEMPERATURES IN THE
RANGE FROM -75C TO -85C HAS BECOME MUCH SMALLER AROUND HURRICANE
STAN DURING THE LAST FIVE HOURS. THE CLOUD TOP TEMPERATURES HAVE
BEEN WARMING AND THE AREAS OF -75C CLOUD TOP TEMPERATURES AND
50000 FOOT CLOUD TOPS NOW ARE CONFINED FROM 19N TO 21N BETWEEN
93W AND 95W...AND INLAND FROM 17N TO 19N BETWEEN 95W AND 97W.
OTHER SHOWERS AND THUNDERSTORMS ARE FOUND IN THE GULF WATERS
FROM 20N TO 23N BETWEEN 93W AND 99W...SCATTERED MODERATE TO
ISOLATED STRONG SHOWERS AND THUNDERSTORMS ALONG THE EASTERN
PACIFIC OCEAN COASTS OF EL SALVADOR...GUATEMALA...AND MEXICO
FROM 12N TO 16N BETWEEN 89W AND 94W...AND ISOLATED MODERATE
SHOWERS AND THUNDERSTORMS IN THE GULF OF MEXICO FROM 21N TO 25N
BETWEEN 84W AND 91W.

A 1006 MB LOW PRESSURE CENTER ACCOMPANIES A SURFACE TROUGH OVER
THE BAHAMAS. THE SURFACE LOW CENTER IS NEAR 23.5N 78W ABOUT
20 NM SOUTH-SOUTHWEST OF THE SOUTHERN PART OF ANDROS ISLAND.
MULTILAYERED CLOUDINESS ASSOCIATED WITH THIS FEATURE IS WEST
OF 20N55W 30N62W. SCATTERED MODERATE TO STRONG SHOWERS AND
THUNDERSTORMS ARE FOUND FROM 24N TO 28N BETWEEN 71W AND 77W.
OTHER SHOWERS AND THUNDERSTORMS TRAIL THIS FIRST AREA...FROM
20N TO 24N BETWEEN 66W AND 74W. UPPER LEVEL ANTICYCLONIC OUTFLOW
STREAMS AWAY FROM THE AREA OF THE TROUGH AND LOW CENTER...
CURVING TOWARD THE NORTHEASTERN CARIBBEAN SEA AND EVENTUALLY
TOWARD THE BASE OF A MIDDLE TO UPPER LEVEL TROUGH POSSIBLY NEAR
18N59W. THE SYSTEM REMAINS POORLY ORGANIZED. UPPER LEVEL WINDS
ARE CURRENTLY UNFAVORABLE FOR TROPICAL CYCLONE FORMATION...BUT
ARE EXPECTED TO BECOME MORE FAVORABLE DURING THE NEXT DAY OR
TWO. THE AIRCRAFT RECONNAISSANCE MISSION SCHEDULED FOR TODAY
HAS BEEN CANCELLED...BUT AN AIRCRAFT WILL BE AVAILABLE TO
INVESTIGATE THE SYSTEM TOMORROW IF NECESSARY. HEAVY RAINS AND
GUSTY WINDS WILL SPREAD ACROSS THE NORTHWESTERN BAHAMAS TODAY
AND THE FLORIDA PENINSULA TOMORROW AS THIS SYSTEM MOVES TOWARD
THE WEST-NORTHWEST. PLEASE CONSULT STATEMENTS ISSUED BY YOUR
LOCAL WEATHER FORECAST OFFICE FOR INFORMATION ON POSSIBLE LOCAL
HAZARDS...INCLUDING FLOOD WATCHES OR WARNINGS.

...TROPICAL WAVES...

AN EASTERN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 29W SOUTH OF
17N MOVING WEST 10 TO 15 KT. ISOLATED SHOWERS FROM 10N TO 12N
BETWEEN 25W AND 34W MAY BE MORE RELATED TO THE ITCZ.

A WESTERN CARIBBEAN SEA TROPICAL WAVE NOW IS MOVING THROUGH
GUATEMALA AND EL SALVADOR ALONG 89W/90W SOUTH OF 17N MOVING
WEST 10 TO 15 KT. IT IS NOT EASY TO DISTINGUISH THE CONVECTIVE
ACTIVITY RELATED SOLELY TO THIS WAVE AS OPPOSED TO THE THE OTHER
NUMEROUS CLOUDS AND SHOWERS AND LARGE SCALE FLOW REGIMES AROUND
AND EAST OF HURRICANE STAN. CENTRAL AMERICA AND THE CARIBBEAN SEA
WEST OF 80W WILL REMAIN IN THIS AREA AS LONG AS THE PATTERN STAYS
THE SAME.

...ITCZ...

ITCZ 12N16W 9N25W 9N31W 9N40W 13N50W 13N60W. SHOWERS AND
THUNDERSTORMS OFF THE AFRICA COAST HAVE BEEN EXPERIENCING WARM
CLOUD TOP TEMPERATURES AND WEAKENING CONVECTIVE ACTIVITY...FROM
4N TO 9N BETWEEN 11W AND 16W. ISOLATED MODERATE SHOWERS ARE
FOUND FROM 2N TO 6N BETWEEN 20W AND 24W...FROM 2N TO 10N BETWEEN
26W AND 40W...AND FROM 5N TO 8N BETWEEN 40W AND 47W.

...DISCUSSION...

THE GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL LOW CENTER IS IN THE NORTHEASTERN
GULF IN COMPLETELY THE OPPOSITE CORNER FROM HURRICANE STAN.
MULTILAYERED MOISTURE AND SOME SHOWERS/THUNDERSTORMS ARE OVER
ATLANTIC OCEAN WATERS FROM EAST OF NORTHERN FLORIDA...BEING
CARRIED ACROSS FLORIDA INTO THE EXTREME NORTHEASTERN GULF
WATERS. HURRICANE STAN IS IN THE SOUTHWESTERN GULF OF MEXICO
GETTING CLOSER AND CLOSER TO LAND IN SOUTHEASTERN MEXICO.
CYCLONIC FLOW AROUND THE NORTHEASTERN GULF LOW CENTER CONTINUES
INTO THE CENTRAL GULF WATERS. THE MIDDLE TO UPPER LEVEL FLOW IS
ANTICYCLONIC NORTH OF 24N WEST OF 90W...NORTH OF STAN. MIDDLE
TO UPPER LEVEL DRY AIR IS NORTH OF 24N/25N WEST OF 90W AND NORTH
OF 25N/26N EAST OF 90W EXCEPT NEAR THE NORTHEASTERN GULF LOW
CENTER AND ITS RELATED MOISTURE.

THE CARIBBEAN SEA...
NUMEROUS STRONG SHOWERS AND THUNDERSTORMS ARE JUST SOUTH OF THE
MONA PASSAGE AND SOUTH OF PUERTO RICO...AT THE TAIL END OF ALL
THE CONVECTIVE ACTIVITY WAY TO THE SOUTHEAST OF THE BAHAMAS
SURFACE LOW CENTER AND TROUGH. ONE SUCH AREA OF PRECIPITATION
GOES FROM 16N TO 18N BETWEEN 67W AND  69W...AND THE OTHER ONE
BY PUERTO RICO FROM 16N TO 18N BETWEEN 65W AND 67W. OTHER SHOWERS
AND THUNDERSTORMS ALSO AT THE TAIL END OF THIS CLOUDINESS ARE
FOUND FROM 16N TO 20N BETWEEN 63W AND 70W. UPPER LEVEL NORTHERLY
FLOW...THE UPPER LEVEL ANTICYCLONIC OUTFLOW FROM HURRICANE
STAN...IS WEST OF JAMAICA. A WEAK AND BROAD LOW CENTER IS NEAR
17N75W JUST SOUTHWEST OF HAITI AND SOUTHEAST OF JAMAICA. A
MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM THIS LOW CENTER
SOUTHWESTWARD TO EASTERN PANAMA. ISOLATED MODERATE SHOWERS ARE
FOUND FROM 9N TO 17N BETWEEN 70W AND 79W AROUND THE PERIMETER
OF THIS CYCLONIC FLOW. A MIDDLE TO UPPER LEVEL TROUGH CONTINUES
ACROSS THE EASTERN AND SOUTHEASTERN CARIBBEAN SEA...STARTING
OUT IN THE ATLANTIC OCEAN. IT LOOKS LIKE THERE IS A WEAK MIDDLE
LEVEL LOW CENTER NEAR 16N57W WITH A TROUGH CONNECTING IT TO
SOUTHEASTERN CARIBBEAN SEA MIDDLE TO UPPER LEVEL LOW CENTER
NEAR 12N64W. A TROUGH CONTINUES FROM THE 12N64W LOW CENTER
TO A MIDDLE LEVEL LOW CENTER ON THE SOUTHWESTERN CORNER OF
LAKE MARACAIBO OF NORTHWESTERN VENEZUELA.

THE ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL LOW CENTER IS NEAR 24N51W WITH A TROUGH
TO 18N59W. MIDDLE TO UPPER LEVEL DRY AIR SURROUNDS THIS 24N51W
LOW CENTER...TO THE NORTH AND WEST AND SOUTH...WITH MOISTURE
INTRUDING INTO THE SYSTEM FROM THE EAST. THE 1013 MB REMNANT
LOW PRESSURE OF T.D. NINETEEN IS NEAR 22N42W MOVING WEST-
NORTHWEST 10 KT. A SURFACE TROUGH RUNS FROM THE T.D. NINETEEN
REMNANT LOW CENTER TO 27N38W AND 31N35W. ISOLATED MODERATE
SHOWERS AND LOCALLY STRONG THUNDERSTORMS ARE FOUND WITHIN 60 NM
ON EITHER SIDE OF 18N38W 24N34W...AND FROM 26N TO 31N BETWEEN
26W AND 30W. WIDELY SCATTERED MODERATE TO ISOLATED STRONG
SHOWERS AND THUNDERSTORMS ARE ON THE SOUTHERN SIDE OF THE
CYCLONIC FLOW OF THIS 24N51W LOW CENTER...FROM 12N TO 16N
BETWEEN 46W AND 60W. A MIDDLE TO UPPER LEVEL TROUGH WELL NORTH
OF THE AREA IS SUPPORTING A COLD FRONT...WHOSE SOUTHERN POINT
PASSES THROUGH 32N49W TO 32N57W. AN UPPER LEVEL RIDGE IS ALONG
11N36W TO 22N29W AND 31N24W. A MIDDLE TO UPPER LEVEL TROUGH IS
DIGGING ITS BASE IN SOUTHERN MOROCCO AND WESTERN MAURITANIA...
SURROUNDED BY MIDDLE TO UPPER LEVEL DRY AIR WITHIN AT LEAST
200 NM ON EITHER SIDE OF THE TROUGH.

$$
MT


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