[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 112348
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE OCT 11 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.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE ALONG 27W/28W S OF 18N MOVING W
10-15 KT. THE WAVE HAS ACQUIRED A NW/SE TILT...LIKELY DUE TO THE
STRONG MID-LEVEL AFRICAN EASTERLY JET "TOPPLING" THE WAVE OVER
NEAR ITS APEX. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
FROM 6N-12N BETWEEN 23W-30W. SCATTERED MODERATE EXTENDING W OF
THE SRN-MOST CAPE VERDE ISLANDS FROM 13N-16N BETWEEN 23W-29W.

CENTRAL ATLANTIC TROPICAL WAVE ALONG 40W S OF 17N MOVING W 10-15
KT. THE NORTHERN PART OF THE WAVE IS MOST WELL-DEFINED...NOTED
BY SHARP CYCLONIC TURNING FROM 12N-17N. ISOLATED SHOWERS/TSTMS
WITHIN 45 NM OF THE AXIS.

TROPICAL WAVE LOCATED 625 NM E OF THE WINDWARD ISLANDS ALONG 50W
S OF 15N MOVING W 10-15 KT. THE WAVE IS EMBEDDED IN MODERATE
NELY TRADE WIND FLOW AND THUS HAS A LOW-AMPLITUDE SIGNATURE.
HOWEVER...A WEAK CIRCULATION IN NOTED WITHIN THE ITCZ ALONG WITH
A PATCH OF ISOLATED SHOWERS/TSTMS FROM 9N-12N BETWEEN 45W-51W.

TROPICAL WAVE LOCATED OVER THE LESSER ANTILLES ALONG 61W S OF
20N MOVING W 5-10 KT. THE WAVE IS ENTERING AN ENVIRONMENT OF
DEEP WESTERLY AND CYCLONIC FLOW OVER THE CARIBBEAN AND W ATLC
WHICH IS MAKING ITS SIGNATURE INCREASINGLY DIFFICULT TO LOCATE.
STRONG SLY LOW-LEVEL FLOW BEGINS NEAR TRINIDAD AND CONTINUES NWD
ACROSS THE ISLANDS FEEDING INTO LOW PRES N OF HISPANIOLA SO IT
IS VIRTUALLY IMPOSSIBLE TO FIND A CYCLONIC WIND SHIFT. SCATTERED
MODERATE CONVECTION EXTENDS MAINLY N AND E OF THE LEEWARD
ISLANDS FROM 14N-21N BETWEEN 58W-63W AND MERGES WITH OTHER
CONVECTION ASSOCIATED WITH THE COMPLEX LOW PRES SYSTEM OVER THE
CARIBBEAN/W ATLC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 13N10W 11N16W 14N26W...THEN ALONG
10N28W 12N37W 10N50W 13N60W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION MOVING OFF THE AFRICAN COAST FROM 6N-15N BETWEEN
9W-16W...EXTENDING FROM COASTAL GUINEA AND SIERRA LEONE NEWD TO
ERN MALI. SCATTERED MODERATE/STRONG CONVECTION FROM 4N-16N
BETWEEN 23W-30W ASSOCIATED WITH THE TROPICAL WAVE ALONG 27W/28W.
WIDELY SCATTERED SHOWERS FROM 3N-10N BETWEEN 30W-40W.

...DISCUSSION...

GULF OF MEXICO...
A LARGE UPPER LEVEL LOW IS LIFTING NEWD ACROSS WRN KANSAS AND
NEBRASKA WITH THE TAIL END OF THE ASSOCIATED TROUGH EXTENDING
SWD INTO FAR NRN MEXICO. THE TROUGH HAS PUSHED A SHALLOW FRONTAL
BOUNDARY INTO NRN MEXICO FROM PIEDRAS NEGRAS TO MONCLOVA...BUT
THE UPPER LEVEL ENERGY IS ALREADY LIFTING AWAY FROM THE AREA SO
THE BOUNDARY HAS BECOME STATIONARY. TSTMS WHICH FORMED ALONG THE
FRONT EARLIER IN THE DAY HAVE PRODUCED SEVERAL OUTFLOW
BOUNDARIES WHICH ARE MOVING OFF THE TEXAS/NE MEXICO COAST...AND
PRODUCING WIDELY SCATTERED SHOWERS/TSTMS FROM 25N-30N BETWEEN
95W-100W. FARTHER E...A SUBSIDENT UPPER HIGH IS CENTERED OVER
THE E GULF NEAR 26N87W AND IS ESSENTIALLY KEEPING SKIES MOSTLY
FAIR E OF 94W. A FEW SHOWERS/TSTMS ARE LOCATED OVER THE FAR SE
GULF DUE TO A LOW-LEVEL TROUGH SWINGING INTO THE STRAITS OF
FLORIDA FROM THE E.

CARIBBEAN AND WEST ATLANTIC...
A LARGE AND COMPLEX UPPER LEVEL TROUGH AND LOW HAS A MEAN CENTER
NE OF THE BAHAMAS NEAR 28N71W AND IS LARGELY AFFECTING THE
WEATHER ALL THE WAY DOWN TO THE NRN COAST OF SOUTH AMERICA. THE
TROUGH IS ADVECTING A JUICY AND MOISTURE-LADEN PLUME FROM THE
PACIFIC COAST OF CENTRAL AMERICA NE TO HISPANIOLA AND PUERTO
RICO THEN NWD OVER THE W ATLC BETWEEN 58W-66W. TWO MAIN SURFACE
LOWS ARE SWIRLING OVER THE AREA...A 1004 MB LOW CLOSE TO THE
TURKS AND CAICOS ISLANDS NEAR 22N70W...AND A 1004 MB LOW IN THE
WINDWARD PASSAGE NEAR 19N75W...BOTH ATTACHED BY AN EXTENDED
TROUGH FROM 26N66W SW ACROSS HAITI AND JAMAICA TO THE GULF OF
HONDURAS. SCATTERED TO NUMEROUS MODERATE CONVECTION WITH
ISOLATED POCKETS OF STRONG CONVECTION EXTEND ACROSS A GOOD
PORTION OF THE CARIBBEAN N OF 10N BETWEEN 66W-86W...FROM PUERTO
RICO AND HISPANIOLA SW TOWARDS NICARAGUA AND COSTA RICA.
SCATTERED MODERATE/STRONG CONVECTION ALSO EXTENDS OVER THE W
ATLC FROM 18N-28N BETWEEN 60W-68W. HEAVY SHOWERS/TSTMS ARE
MOVING ACROSS PORTIONS OF THE VIRGIN ISLANDS...PUERTO RICO...AND
HISPANIOLA AND THE PATTERN IS EXPECTED TO CHANGE LITTLE THROUGH
THE REST OF THE WEEK WHICH WILL ONLY INCREASE THE FLOODING
THREAT OVER THESE ISLANDS. ELSEWHERE...ISOLATED SHOWERS/TSTMS
HAVE FORMED OVER PARTS OF FLORIDA AND CUBA TODAY DUE TO A
SURFACE TROUGH SWINGING FROM THE NW BAHAMAS TO THE STRAITS OF
FLORIDA...AND A COASTAL STATIONARY FRONT EXTENDING FROM 32N79W
28N81W.

EAST/CENTRAL ATLANTIC...
AN UPPER LEVEL LOW IS CUTTING OFF OVER THE CENTRAL ATLC NEAR
17N47W AND IS DRIFTING SW...ESSENTIALLY REINFORCING THE
TROUGHING PATTERN OVER THE AREA. THE LOW IS BEGINNING TO
INCREASE THE SWLY MOISTURE PLUME TO ITS E BUT AS OF RIGHT NOW
MOISTURE IS SOMEWHAT LIMITED OVER THE TROPICS BETWEEN 37W-57W. A
SURFACE RIDGE EXTENDS FROM A 1018 MB HIGH NEAR 26N24W NW PAST
32N46W BUT AN UPPER LEVEL SHORTWAVE TROUGH AND ASSOCIATED COLD
FRONT ARE NEARING THE AREA FROM THE N AND BEGINNING TO BREAK
DOWN THE RIDGE. A FAIRLY MODEST 50-60 KT W/SW JET EXTENDS ACROSS
THE CANARY ISLANDS TOWARDS NRN MOROCCO IN THE UPPER
LEVELS...WHICH IS CAUSING A SMALL PATCH OF ISOLATED SHOWERS FROM
23N-28N BETWEEN 12W-20W...SOME OF WHICH ARE PROBABLY MOVING OVER
THE CANARY ISLANDS RIGHT NOW. FARTHER S...AN UPPER LEVEL HIGH IS
CENTERED S OF THE CAPE VERDE ISLANDS NEAR 10N25W AND IS
PRODUCING A DIFFLUENT UPPER LEVEL ENVIRONMENT S OF 20N E OF 40W.
THIS HAS ALLOWED CONVECTION TO STRENGTHEN AND INCREASE ITS
COVERAGE ADJACENT TO THE TROPICAL WAVE ALONG 27W/28W.

$$
BERG


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