[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111802
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT NOV 11 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
1745 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 56W S OF 15N MOVING W NEAR 15 KT. THE
WAVE WAS ADJUSTED E OVERNIGHT...WHICH WAS A GOOD MOVE...AS
VISIBLE IMAGERY SHOWS CLEAR BUT LOW AMPLITUDE CYCLONIC TURNING
OF THE LOWER CLOUD FIELD ABOUT THE WAVE AXIS. THIS WAVE HAS
SIGNIFICANTLY WEAKENED OVER THE LAST COUPLE OF DAYS AS MODERATE
TO STRONG SW-WLY WINDS ALOFT IN COMBINATION WITH STRONG
SUBSIDENCE HAVE TAKEN THEIR TOLL ON THIS ONCE ACTIVE TROPICAL
WAVE. A COUPLE OF SMALL CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION NOTED FROM 10N-13N WITHIN 100NM OF THE AXIS.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N13W 7N25W 8N50W 10N59W 8N63W.
SMALL CLUSTER OF MODERATE CONVECTION NOTED NEAR 9N20W. ISOLATED
SHOWERS/TSTMS FROM 7N-11N BETWEEN 38W-48W. MINIMAL ACTIVITY
NOTED ELSEWHERE WITHIN 200 NM EITHER SIDE OF THE AXIS.

...DISCUSSION...
GULF OF MEXICO...
UPPER SW/W FLOW DOMINATES THE GULF AROUND UPPER RIDGING FROM THE
NW CARIBBEAN AND OFF THE EAST COAST...ALONG WITH THE APPROACHING
TROUGH MOVING THROUGH THE NATIONS MID SECTION AND INTO THE NW
GULF. THIS BROAD W/SW FLOW IS ADVECTING DEBRIS MOISTURE THROUGH
MUCH OF THE GULF...DOWNSTREAM FROM THE VERY ACTIVE EAST PACIFIC.
SCATTERED MODERATE CONVECTION NOTED IN THE WRN GULF FROM 19N-25N
BETWEEN 94W-98W IN ASSOCIATION WITH THE SFC COLD FRONT THAT HAS
MOVED INTO THE GULF. AS OF 1500 UTC THE COLD FRONT IS ANALYZED
FROM NEAR BILOXI MISSISSIPPI TO 24N95W 23N98W. 20-25KT N/NE
WINDS HAVE DEVELOPED BEHIND THE FRONT WITH A 1030 MB SFC HIGH
BUILDING FROM N TEXAS. MUCH LIGHTER...MORE VARIABLE FLOW IS
AHEAD OF THE FRONT WITH A WEAK GRADIENT AROUND A NEWLY FORMED
1020 MB HIGH NEAR 25N87W. HIGH PRESSURE WILL CONTINUE TAKING
OVER THE GULF PATTERN FROM THE N WHILE WEAKENING THROUGH
MONDAY...AS THE COLD FRONT PUSHES E/SE AND OUT OF THE AREA.

CARIBBEAN SEA...
THE CARIB REMAINS QUIET THIS AFTERNOON WITH PLENTY OF
DRY/STABLE SINKING AIR ALOFT IN PLACE. THE MID-UPPER LEVEL
PATTERN PRODUCING THIS STABLE ENVIRONMENT CONSISTS OF AN UPPER
HIGH CENTERED IN THE NW CARIB NEAR 17N83W AND ANOTHER RIDGE
EXTENDING N THROUGH THE ERN CARIBBEAN AND LESSER ANTILLES. A
WEAK UPPER TROUGH IN THE MIDDLE EXTENDS S THROUGH THE CNTRL
CARIB S OF HISPANIOLA. AT THE SFC...THERE DOES APPEAR TO BE A
NARROW ZONE OF LOW LEVEL CONFLUENCE THAT WEAVES ITS WAY THROUGH
THE CARIBBEAN WATERS FROM HAITI TO THE YUCATAN...BUT THERE IS NO
DEEP CONVECTION ASSOCIATED WITH A PIECE OF WHAT SEEMS TO BE THE
OLD ATLC FRONTAL BOUNDARY TO THE NE. ONE CLUSTER OF SCATTERED
MODERATE CONVECTION NOTED OFF THE COAST OF PANAMA ASSOCIATED
WITH THE ITCZ. TRADE WINDS ARE MODERATE AND WILL LIKELY REMAIN
THAT WAY OVER THE NEXT COUPLE DAYS.

ATLANTIC OCEAN...
UPPER RIDGE EXTENDS N THROUGH THE SW NORTH ATLC ACCOMPANIED BY
PLEASANT WEATHER WITH JUST A FEW HIGH CLOUDS/DEBRIS MOISTURE
EXTENDING THROUGH THE REGION. A 1020 MB SFC HIGH ALSO NOTED NEAR
32N75W...PRODUCING LIGHT WINDS/LOW SEAS. A NARROW UPPER TROUGH
EXTENDING S ALONG 51W HAS AN ASSOCIATED SFC COLD FRONT ALONG
32N53W 23N60W TO NEAR THE N COAST OF THE DOMINICAN REPUBLIC. A
PRE-FRONTAL TROUGH LIES ABOUT 150 NM AHEAD OF THE FRONT N OF
25N. ONLY LOW AND MID LEVEL CLOUDS AND ISOLATED SHOWERS ARE
ALONG THE FRONT AND TROUGH WITH THE UPPER SUPPORT NOW CUT OFF.
SHORTWAVE UPPER RIDGE EXTENDS N THROUGH THE CENTRAL ATLC ALONG
42W N OF AN UPPER HIGH E OF THE LEEWARD ISLANDS. E OF THE
RIDGE...THE PATTERN IS DOMINATED BY A LARGE CUT OFF UPPER LOW
CENTERED NEAR 32N31W. THIS UPPER FEATURE HAS A RELATED SFC LOW
WHICH IS ANALYZED AT 1008 MB JUST E OF THE UPPER-LEVEL CENTER.
MOST OF THE WEATHER IS E OF THE SFC LOW...WHERE SCATTERED
MODERATE CONVECTION EXISTS N OF 27N BETWEEN 22W-26W...LINED
ALONG A SFC TROUGH. IN THE DEEP TROPICS...THE MAIN FEATURE IS A
WELL-DEFINED UPPER LEVEL JET STREAM WHICH ORIGINATES NEAR
VENEZUELA AND RACES ENE TO THE W COAST OF AFRICA. THE JET IS
HEAVILY SHEARING THE CLOUD TOPS OVER THE ITCZ CONVECTION.

$$
WILLIS






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