[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 220517
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON AUG 22 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0345 UTC.

...SPECIAL FEATURE...

A 1008 MB LOW IS CENTERED ABOUT 160 NM SW OF THE SOUTHERNMOST
CAPE VERDE ISLANDS NEAR 14N27W...ALONG A TROPICAL WAVE ALONG 27W
THAT EXTENDS S OF 21N AND IS MOVING W 10-15 KT. SEVERAL LOW AND
MID-LEVEL LAYERS OF CLOUDS ARE MAKING THE EXACT CENTER OF THE
LOW A LITTLE DIFFICULT TO LOCATE...BUT THE BEST ESTIMATE PUTS IT
ABOUT A DEGREE N OF THE DEEPEST CONVECTION. THE CONVECTIVE
INTENSITY REMAINS THE SAME AS THIS AS EARLIER THIS EVENING WITH
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM
11N-15N BETWEEN 25W-31W. LOW-LEVEL MOISTURE IS ALSO BEING PULLED
UP BEHIND THE WAVE AXIS AND MAY PRODUCE A FEW SHOWERS OVER THE
CAPE VERDES OVERNIGHT. GIVEN THE LARGE CIRCULATION AND LOW
PRESSURE NEAR THE CENTER...TROPICAL CYCLONE DEVELOPMENT IS
POSSIBLE WITHIN THE NEXT 36 HRS.

...TROPICAL WAVES...

SEE SPECIAL FEATURES FOR TROPICAL WAVE/LOW ALONG 27W.

WEAK TROPICAL WAVE ALONG 51W S OF 20N MOVING W 15-20 KT. WEAK
WAVE WITH AN EXTREMELY POOR SIGNATURE AND IS ONLY ASSOCIATED
WITH A SLIGHT CYCLONIC TURNING IN THE CLOUD FIELD. NO ASSOCIATED
DEEP CONVECTION.

CENTRAL CARIBBEAN TROPICAL WAVE ALONG 75W S OF 20N MOVING W
15-20 KT. THE N PORTION OF THIS WAVE HAS BROKEN OFF AND MERGED
WITH THE SURFACE TROUGH THAT EXTENDS FROM 25N70W TO OVER HAITI
AND IS MOVING NW AT 10-15 KT. EXTREMELY CLEAR WEATHER IS OVER
THE CENTRAL CARIBBEAN S OF 17N NEAR THE WAVE AXIS.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 15N16W 18N24W...THEN ALONG 10N30W
12N40W 10N49W 13N58W. SCATTERED MODERATE/STRONG CONVECTION IS
MOVING OFF AFRICA FROM 9N-15N E OF 19W. ABUNDANT TROPICAL
MOISTURE IS S OF THE ITCZ AXIS BETWEEN 25W-45W WITH WIDELY
SCATTERED SHOWERS.

...DISCUSSION...

GULF OF MEXICO...
PRIMARY FOCUS FOR THE EVENING IS OVER NW GUATEMALA AND S MEXICO
WITH A 1009 MB LOW CENTERED NEAR 18N92W MOVING NW TOWARDS CIUDAD
DEL CARMEN MEXICO. THE LOW IS AMAZINGLY WELL-DEFINED FOR BEING
INLAND AND THE OBS OVER S MEXICO SHOW A GOOD CYCLONIC
CIRCULATION...HOWEVER IT APPEARS TO BE WEAKENING SLIGHTLY. THIS
SYSTEM COULD BECOME BETTER ORGANIZED WHEN IT EMERGES OVER THE
GULF OF MEXICO OVER THE NEXT 24 HOURS. SCATTERED MODERATE/
ISOLATED STRONG CONVECTION IS ACROSS THE BAY OF CAMPECHE S OF
20N. THE SURFACE LOW IS S OF AN UPPER LEVEL INVERTED TROUGH THAT
EXTENDS FROM W CUBA ACROSS THE YUCATAN PENINSULA TO OVER CENTRAL
MEXICO...THUS CONDITIONS COULD BECOME MORE FAVORABLE FOR FURTHER
DEVELOPMENT AS THE LOW MOVES INTO THE GULF. ELSEWHERE...A MUCH
LARGER UPPER HIGH IS CENTERED OVER S ALABAMA WITH A LARGE AREA
OF EASTERLIES FLOWING ACROSS FLORIDA AND THE GULF N OF 24N.
LARGE AREA OF SHOWERS/THUNDERSTORMS ARE OVER MISSISSIPPI AND
LOUISIANA WITH A SQUALL LINE OFF THE LOUISIANA COAST MOVING SW.
ISOLATED SHOWERS ARE MOVING W ACROSS THE CENTRAL GULF FROM
23N-28N BETWEEN 83W-97W.

CARIBBEAN...
AN UPPER LEVEL INVERTED TROUGH EXTENDS OVER THE NW CARIBBEAN
FROM NEAR 20N80W TO THE W TIP OF CUBA AND HAS SPARKED AN AREA OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 17N-23N
BETWEEN 75W-88W...SPREADING ACROSS JAMAICA...CUBA...AND THE
CAYMAN ISLANDS. ELSEWHERE...AN UPPER HIGH IS CENTERED NEAR THE
WINDWARD PASSAGE AND IS REINFORCING DEEP EASTERLY FLOW ACROSS
THE E/CENTRAL CARIBBEAN. HOWEVER...THIS FLOW IS ABNORMALLY DRY
SO THERE IS LITTLE IF ANY IN THE WAY OF TRADE SHOWERS BETWEEN
THE LESSER ANTILLES AND 77W S OF 17N. HOWEVER...SCATTERED
MODERATE/STRONG CONVECTION EXTENDS FROM OVER THE TURKS AND
CAICOS TO HAITI WITHIN 60/75 NM OF LINE 23N70W-18N74W. SOME OF
THE DRY AIR IS BEING DRAGGED S BY ANOTHER UPPER TROUGH FROM
15N80W TO THE COLOMBIAN COAST...AND ALL THE UPPER MOISTURE IS
LIMITED TO S OF 11N WHERE THE FLOW IS WESTERLY. ELSEWHERE...AN
INVERTED UPPER TROF IS MOVING INTO THE E CARIBBEAN FROM AN UPPER
LOW ALONG THE COAST OF VENEZUELA NEAR 11N64W TO 20N60W AND IS
COLLOCATED WITH A SURFACE TROUGH EXTENDING FROM BARBADOS ACROSS
THE EASTERN MOST LEEWARD ISLANDS TO 22N63W. THESE FEATURES ARE
PRODUCING SCATTERED SHOWERS/THUNDERSTORMS WITHIN 75/90 NM OF
LINE 14N60W TO 24N64W...SPREADING ACROSS THE ISLANDS FROM
DOMINICA TO ANGUILLA.

WEST ATLANTIC...
AN UPPER RIDGE AXIS EXTENDS NE OFF THE COAST OF GEORGIA TO
BEYOND BERMUDA AND IS PRODUCING MODERATE NE FLOW OVER THE W ATLC
AND ACROSS THE NRN BAHAMAS AND FLORIDA. THIS FLOW LIES ON THE W
SIDE OF AN UPPER LOW LOCATED BETWEEN PUERTO RICO AND BERMUDA
NEAR 26N67W...WITH A TROUGH EXTENDING SW ACROSS TO THE S BAHAMA
ISLANDS. STRONG UPPER DIFFLUENCE E OF THE TROUGH IS HELPING TO
PRODUCE THE SCATTERED MODERATE/STRONG CONVECTION EXTENDING FROM
OVER THE TURKS AND CAICOS TO HAITI WITHIN 60/75 NM OF LINE
23N70W-18N74W.

EAST/CENTRAL ATLANTIC...
A CUT-OFF MID/UPPER LOW IS CENTERED NEAR THE N BOUNDARY OF THE
DISCUSSION AREA NEAR 31N48W AND IS MOVING SLOWLY W ABOUT 5
KT. THE LOW IS PRODUCING EXTREMELY ISOLATED SHOWERS N OF 26N
BETWEEN 45W-50W. BROAD MID/UPPER LEVEL HIGH IS IN THE S/CENTRAL
ATLC ROUGHLY CENTERED NEAR 24N36W AND EXTENDS ANTICYCLONIC FLOW
S TO NEAR 16N WITH A SHARP RIDGE AXIS EXTENDING N TO NEAR
32N38W...BETWEEN TWO UPPER LOWS. THE UPPER LEVEL ENVIRONMENT
BEING PARTICULARLY DRY OVER THE CNTRL ATLC...WITH THE AREA OF
STRONG SUBSIDENCE LOCATED WITHIN 200/250 NM OF A LINE FROM
31N36W 23N44W 10N52W WITH THE MOST ABUNDANT TROPICAL MOISTURE
LIMITED S OF THE HIGH. ANOTHER MID/UPPER LOW IS LOCATED JUST NW
OF THE CANARY ISLANDS NEAR 30N22W AND IS PRODUCING ISOLATED
SHOWERS TO ITS S FROM 24N-28N BETWEEN 19W-25W.

$$
WALLACE


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