[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 062346
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU OCT 06 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

1010 MB LOW IS OVER THE CENTRAL ATLANTIC ABOUT 1150 NM E OF THE
WINDWARD ISLANDS NEAR 10N43W AND IS ASSOCIATED WITH A TROPICAL
WAVE ALONG 43W S OF 15N WHICH IS MOVING W 10-15 KT.  LAST
VISIBLE IMAGES SHOW A MID-LEVEL LOW NEAR 8N44W WHICH SEEMS TO BE
DECOUPLED WITH THE LOW-LEVEL CIRCULATION.  SURFACE OBSERVATIONS
INDICATE THERE IS AT LEAST A BROAD LOW IN THE WAVE BUT THERE ARE
NO PARTICULAR BANDING FEATURES ON SATELLITE TO SUGGEST
DEVELOPMENT.  HOWEVER UPPER-LEVEL WINDS ARE STILL FAVORABLE FOR
SOME ORGANIZATION WITH WIDELY SCATTERED TSTMS REFIRING IN THE
NORTHERN PART OF THE WAVE FROM 12N-18N BETWEEN 40W-46W.  A FEW
TSTMS ARE WITHIN 60 NM OF 11N46W.  TROPICAL CYCLONE DEVELOPMENT
IS POSSIBLE WITHIN THE NEXT 36 HRS WITH THIS SYSTEM...ESPECIALLY
IF CONVECTION CONSOLIDATES CLOSER TO THE LOW CENTER OR A NEW LOW
DEVELOPS WITHIN THE STRONGEST CONVECTION.

A 1012 MB LOW IS NEAR 22.5N54.5W IN THE CENTRAL ATLC MOVING W
5-10 KT.  SATELLITE IMAGES INDICATE THE SYSTEM HAS GOTTEN A
LITTLE MORE ORGANIZED DURING THE DAY.  THE LOW-LEVEL CIRCULATION
IS BETTER-DEFINED AND TSTM ACTIVITY HAS INCREASED WITH WIDELY
SCATTERED TSTMS FROM 22N-28N BETWEEN 50W-58W.  HOWEVER THE
SYSTEM REMAINS EMBEDDED WITH A DEEP-LAYERED LOW PRESSURE SYSTEM
WHICH IS NOT THE IDEAL PLACE FOR TROPICAL CYCLONE DEVELOPMENT.
COMPUTER MODELS SUGGEST THAT THE UPPER LOW WILL DROP MORE TO THE
SOUTH AND POSSIBLY ALLOW THE SURFACE LOW TO DEEPEN IN THE NEXT
FEW DAYS AS RIDGING BUILDS IN THE UPPER-LEVELS.

...TROPICAL WAVES...

E CARIBBEAN TROPICAL WAVE ALONG 67W S OF 18N MOVING W 10 KT.
THERE IS NO WELL-DEFINED AXIS AXIS WITH ONLY ISOLATED MODERATE
CONVECTION OCCURRING FROM 14N-17N BETWEEN 65W-70W.  MOISTURE
FROM THIS WAVE WILL LIKELY ADD TO THE WET CONDITIONS OVER
HISPANIOLA FOR THE NEXT SEVERAL DAYS.

...ITCZ...

ITCZ IS CENTERED ALONG 11N16W 11N21W 10N30W 12N39W 9N61W.  THE
ITCZ IS ILL-DEFINED W OF 40W.  WIDELY SCATTERED MODERATE IS
WITHIN 45 NM OF THE ITCZ BETWEEN 20W-31W.  CLUSTERS OF TSTMS ARE
WITHIN 75 NM OF 5.5N27W.

...DISCUSSION...

NORTHERN MEXICO...
A STRONG COLD FRONT MOVED ACROSS THE U.S.-MEXICO BORDER EARLIER
THIS MORNING AND NOW EXTENDS FROM JUST N OF LAREDO TEXAS THEN
STATIONARY ACROSS THE MOUNTAINS TO S OF CHIHUAHUA MEXICO THEN TO
TUCSON ARIZONA. WIDESPREAD STRATUS AND ISOLATED SHOWERS/TSTMS
EXTEND N OF THE FRONTAL BOUNDARY INTO W TEXAS AND ERN NEW MEXICO.

GULF OF MEXICO...
A COMPLEX PATTERN REMAINS OVER THE GULF WATERS AND IS CAUSING
WET WEATHER EXTENDING FROM SRN MEXICO TO W CUBA THEN NWD ACROSS
MOST OF FLORIDA. AN UPPER LEVEL TROUGH IS LOCATED ALONG
88W...WITH AN EMBEDDED UPPER LOW NEAR 28N88W...AND IS DRAWING
EXTENSIVE TROPICAL MOISTURE FROM CENTRAL AMERICA NWD INTO THE SE
USA. THE REMNANTS OF T.D. TAMMY ARE NEAR 30N86W AND ARE PART OF
A SURFACE TROUGH WHICH EXTENDS S OF 27N84.5W 22N88W THEN INTO
THE BAY OF CAMPECHE.  A PAIR OF 1004 MB LOWS ARE NOTED ON
VISIBLE SATELLITE PICTURES NEAR 22N88W AND 24.5N86W.   SCATTERED
SHOWERS/TSTMS ARE NEAR AND E OF THE TROUGH OVER THE GULF E OF
85W AND ALSO N OF 29N E OF 89W.  MUCH DRIER AIR HAS FILTERED IN
BEHIND THE TROUGH LEAVING MOSTLY FAIR SKIES OVER THE CENTRAL/W
GULF EXCEPT CLOSE TO THE REMNANTS OF TAMMY.  ANOTHER AREA OF
CONCERN IS A 1003 MB LOW CENTERED NEAR THE W TIP OF CUBA NEAR
23N83W. ALTHOUGH THIS FEATURE IS PRODUCING SOME STRONG
CONVECTION OVER THE NW CARIBBEAN AND WILL LIKELY DRAG THIS
MOISTURE NWD TOWARDS FLORIDA OVER THE NEXT 24 HRS...CONDITIONS
NO LONGER LOOK AS FAVORABLE FOR TROPICAL CYCLONE DEVELOPMENT
WITH STRONG SLY SHEAR. PLENTY OF TSTMS ARE HEADED NORTHWARD FROM
E OF THIS LOW ACROSS W CUBA AND THE STRAITS OF FLORIDA TOWARD
THE FL PENINSULA.   COMPUTER MODELS SUGGEST WET CONDITIONS ARE
LIKELY FOR FLORIDA.. W CUBA INTO CENTRAL AMERICA FOR THE SEVERAL
DAYS DUE TO THE SLOW EVOLUTION OF THIS SYSTEM.

CARIBBEAN...
THE LOW NEAR THE W TIP OF CUBA AND THE SHARP UPPER TROUGH OVER
THE GULF OF MEXICO IS INDUCING A LARGE AREA OF SCATTERED
MODERATE ISOLATED STRONG CONVECTION NEAR AND W OF THE CAYMAN
ISLANDS FROM 17.5N-22N BETWEEN 81W-86W...SOMEWHAT IN THE
STRUCTURE OF A BROKEN SQUALL LINE. ISOLATED MODERATE CONVECTION
ALSO EXTENDS SE OF THIS AREA FROM 15N-18N BETWEEN 78W-82W WITH
OTHER TSTMS OVER E CUBA. ALL THIS ACTIVITY IS BEING FED BY A
DEEP POOL OF TROPICAL MOISTURE FROM DEEP-LAYERED SW WINDS ALL
THE WAY FROM THE EPAC THROUGHOUT THE NW CARIBBEAN WHICH IS
EXPECTED TO REMAIN IN PLACE FOR AT LEAST THE NEXT 3-4 DAYS.
ADDITIONAL SHOWERS/TSTMS EXTEND FARTHER E OVER HISPANIOLA IN
ASSOCIATED WITH A TROPICAL WAVE...BUT MOST OF THE AREA S OF 14N
IS UNDER MAINLY FAIR SKIES AND DRIER LOW-LEVEL AIR.  THE SW SIDE
OF AN UPPER TROUGH AND A WEAK LOW-LEVEL TROUGH FROM NEAR 15N61W
NEAR DOMINICA WNW TO 16N66W ARE COMBINING TO PRODUCE SCATTERED
TSTMS OVER THE E CARIBBEAN FROM 13N-16.5N BETWEEN 60W-64W.
THERE MAY EVEN BE A WEAK LOW ON THAT TROUGH NEAR 15.5N62W BUT
NLY SHEAR IS TOO STRONG TO ALLOW TROPICAL CYCLONE DEVELOPMENT.
WET WEATHER SHOULD REMAIN ABOUT IN PLACE FOR TOMORROW THEN BEGIN
TO SHIFT TOWARD THE LEEWARD ISLANDS & PUERTO RICO BY LATE SAT.

ATLANTIC...
A SHARP UPPER LEVEL RIDGE EXTENDS OVER THE W ATLC WATERS FROM
THE WINDWARD PASSAGE THRU THE CAROLINAS AND IS SPREADING HIGH
LEVEL CIRRUS ACROSS MOST OF THE AREA W OF 60W. WIDELY SCATTERED
MODERATE CONVECTION ARE OVER THE NW BAHAMAS NNW ALONG THE E
FLORIDA COAST TO THE CAROLINAS N OF 25NW OF 77W.  FARTHER E...A
CUT-OFF UPPER LOW IS CENTERED NEAR 22N55W AND IS DISCUSSED IN
THE SPECIAL FEATURES ABOVE. THE UPPER TROUGH IS ALSO INTERACTING
WITH A SURFACE TROUGH ALONG 19N52W 16N56W TO PRODUCE ADDITIONAL
SCATTERED MODERATE CONVECTION WITHIN 150 NM TO THE SE OF THE
TROUGH.  DIVERGENCE FROM THE UPPER TROUGH IS ASSISTING SCATTERED
TSTMS FROM 17N-21N BETWEEN 44W-49W WITH MORE ISOLATED ACTIVITY
FROM 22N-28N IN THE SAME LONGITUDES.  AN UPPER HIGH.. MUCH
FARTHER N THAN AVERAGE FOR OCTOBER.. IS NEAR 13N34W RIDGING WSW
TO 11N49W.  FLOW BETWEEN THIS HIGH WHICH EXTENDS EASTWARD TO
SENEGAL AND A LARGE DEEP-LAYERED LOW SE OF THE AZORES IS NEAR 80
KT BUT IS NOT PRODUCING ANY SIGNIFICANT WEATHER.  REMNANT TROUGH
LIES FROM 31N22W TO 28N28W WITH ISOLATED SHOWERS WITHIN 60 NM OF
THE FEATURE.

$$
BLAKE

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