[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 031731
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE OCT 03 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE 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.

...TROPICAL WAVES...
A 1010 MB LOW IS CENTERED NEAR 11N36W MOVING WNW NEAR 10 KT. THE
LOW LEVEL CIRCULATION IS EASILY SEEN ON VISIBLE IMAGES AND 0810
UTC QUIKSCAT PASS WHICH SHOWED SEVERAL UNCONTAMINATED 20 TO 25
KT WIND VECTORS TO THE N OF THE CIRCULATION CENTER. ASSOCIATED
SHOWERS AND TSTMS ARE DISORGANIZED AND ARE BEING STRETCHED WELL
TO THE N/NE OF THE LOW AS STRONG UPPER LEVEL SOUTHWESTERLY WINDS
AHEAD OF LARGE TROUGH IS SHEARING THE SYSTEM. SCATTERED SHOWERS
AND TSTMS ARE FROM 9N-20N BETWEEN 31W-38W

A TROPICAL WAVE IS ALONG 47W/48W S OF 15N MOVING W NEAR 10 KT.
THIS WAVE IS LOW AMPLITUDE AND IS GENERATING LITTLE SHOWERS AND
TSTMS. DESPITE THE LIMITED ACTIVITY...THE WAVE AXIS IS NOT VERY
CHALLENGING TO LOCATE WITH LOW-MID LEVEL CLOUDS VEERING
CYCLONICALLY ABOUT THE AXIS. THIS WAVE WILL LIKELY PICK UP SOME
FORWARD SPEED AS IT TRACKS TO THE S OF A CNTRL ATLC RIDGE.

A TROPICAL WAVE IS ALONG 66W S OF 21N MOVING W 10 KT. A HINT OF
AN INVERTED V STRUCTURE IS NOTED ON SATELLITE IMAGES. THIS WAVE
IS INTERACTING WITH A SMALL UPPER LOW TO ITS W TO PRODUCE
SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 240 NM EITHER SIDE
OF THE WAVE AXIS.

A TROPICAL WAVE IS ALONG 87W S OF 18N MOVING W 10 TO 15 KT OVER
THE PAST 24 HOURS. THIS WAVE IS ILL-DEFINED AND CHALLENGING TO
TRACK. SOME SLIGHT LOW-MID LEVEL CURVATURE EXISTS ABOUT THE BASE
OF THE WAVE IN THE EPAC. SCATTERED SHOWERS AND TSTMS ARE N OF
15N NEAR THE AXIS LIKELY ENHANCED BY UPPER DIFFLUENT AIR.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 9N13W 5N28W 8N39W 7N58W. BESIDES FOR
CONVECTION ASSOCIATED WITH THE 1010 MB...THE ITCZ IS FAIRLY
INACTIVE WITH ISOLATED MODERATE FROM 4N-12N E OF 18W. THIS
ACTIVITY MIGHT BE ASSOCIATED WITH A WEAK TROPICAL WAVE MOVING
OFF THE COAST OF AFRICA AS SUGGESTED BY AVAILABLE SFC AND
SOUNDING DATA. OTHERWISE ISOLATED SHOWERS DOT THE AXIS.

...DISCUSSION...
GULF OF MEXICO...
A BROAD MID TO UPPER LEVEL RIDGE CENTERED OVER S MEXICO COVERS
THE GULF. A CONSIDERABLE AMOUNT OF MOISTURE IS LOCKED IN THE
RIDGE...HOWEVER MOST OF IT IS NOT VERY DEEP IN NATURE. THE
DEEPEST AVAILABLE MOISTURE IS IN THE WRN GULF WHERE SCATTERED
SHOWERS AND ISOLATED TSTMS ARE MAINLY W OF 90W FROM 20N-28N...A
WEAK SFC TROUGH MAY BE FORMING IN THIS AREA ENHANCING THIS
ACTIVITY. A WEDGE OF VERY DRY AIR ALOFT COVERS THE EXTREME SE
GULF E OF THE WRN ATLC TROUGH. AT THE SFC...A 1026 MB HIGH
ANALYZED IN CNTRL/WRN NORTH CAROLINA IS SETTING UP A TIGHTENED
PRES GRAD INCREASING ENE WINDS TO 20 KT IN THE SE GULF. LIGHTER
EASTERLY 10 TO 15 KT WINDS ARE OBSERVED IN THE WRN GULF. THESE
WINDS ARE EXPECTED TO REMAIN MODERATE OVER THE NEXT FEW DAYS AS
A LARGE STRONG CANADIAN HIGH PUSHES SOUTHEASTWARD KEEPING A
TIGHT PRES GRAD ACROSS THE AREA. THIS WILL ALLOW E SWELL TO
BUILD FOR THE WRN GULF WATERS AND COASTAL TEXAS/NE MEXICO.

CARIBBEAN SEA...
THE TAIL END OF A SHARP WRN ATLC TROUGH EXTENDS INTO THE WRN
CARIBBEAN. UPPER DIFFLUENCE ON THE E SIDE OF THE TROUGH IS
PRODUCING SCATTERED SHOWERS AND TSTMS N OF 17N BETWEEN 72W AND
80W WHICH INCLUDES WRN HAITI...JAMAICA...THE CAYMAN ISLANDS AND
CNTRL AND ERN CUBA. DRY MID-UPPER LEVEL AIR LIES TO THE S OF THE
TROUGH FROM 12N TO 17N BETWEEN 70W AND 83W. SCATTERED SHOWERS
AND TSTMS ARE ALSO OCCURRING IN THE ERN CARIBBEAN DUE TO THE
INTERACTION BETWEEN A TROPICAL WAVE ALONG 66W AND A SMALL UPPER
LOW NEAR PUERTO RICO. SEE TROPICAL WAVES SECTION FOR MORE
DETAILS. SIMILAR ACTIVITY IS IN THE EXTREME WRN PORTION WHERE
DEBRIS MOISTURE FROM THE GULF IS ROTATION ANTICYCLONICALLY
AROUND THE BROAD RIDGE OVER S MEXICO. SCATTERED MODERATE
CONVECTION IS OVER WRN COLOMBIA...PANAMA AND THE SW CARIBBEAN
WATERS S OF 10N...ASSOCIATED WITH THE ITCZ. GFS SUGGESTS THAT
SOME OF THIS TROPICAL MOISTURE MAY MOVE NWD OVER THE NEXT FEW
DAYS. TRADE WINDS ARE NEAR 20 KT AND SEAS TO 8 FT FROM 11N TO
17N FROM 70W TO 80W.

ATLANTIC OCEAN...
AN AMPLIFIED MID TO UPPER LEVEL PATTERN EXISTS ACROSS THE ATLC
BASIN. AN UPPER TROUGH AXIS IS ALONG 75W AND DIGS WELL SWD INTO
THE NW CARIBBEAN. THE SRN PORTION OF THE TROUGH APPEARS AS IT IS
BECOMING CUT OFF AS THE SWLY JET ASSOCIATED WITH IT WEAKENS.
STRONG SUBSIDENCE IS LOCATED BEHIND THE TROUGH AXIS AND A SWATH
OF MOISTURE IS LOCATED TO THE E OF THE AXIS BETWEEN 60W AND 73W
ADVECTED BY THE SW JET MENTIONED. THE ASSOCIATED SFC OLD FRONTAL
BOUNDARY IS ALONG 31N61W 27N69W TO THE CNTRL BAHAMAS. A
MID-LEVEL SUBTROPICAL RIDGE IS LOCATED TO THE E OF THE TROUGH
AND COVERS THE REGION BETWEEN 40W AND 55W N OF 25N. PLENTY OF
DRY STABLE AIR IS IN PLACE UNDER THE INFLUENCE OF THIS RIDGING.
MUCH OF THE ERN ATLC IS DOMINATED BY A LARGE HIGHLY NE-SW
ELONGATED UPPER TROUGH ANCHORED BY A VERY LARGE DEEP LAYER LOW
NEAR 31N31W.  THE SFC LOW ASSOCIATED WITH THIS SYSTEM IS
ANALYZED AT 1009 MB...BUT THE HIGHEST AMPLITUDE IS LIKELY OFF
THE SURFACE. THIS NON-TROPICAL LOW IS NOT SHOWING ANY SIGNS OF
BECOMING SUBTROPICAL AND MOST OF THE GLOBAL MODELS SHOW A TRACK
TO THE N AND DISSIPATE IT LATER THIS WEEK. HIGHLY SHEARED
SHOWERS AND TSTMS ASSOCIATED WITH A 1010 MB LOW NEAR 11N36W ARE
FROM 9N TO 21N BETWEEN 30W AND 38W. IN THE FAR EASTERN ATLC...AN
UPPER HIGH IS CENTERED OVER WRN AFRICA NEAR 17N16W WITH RIDGING
EXTENDING TO THE CAPE VERDE ISLANDS.

$$
CANGIALOSI


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