[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211727
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST THU DEC 21 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...
METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 6N10W 4N25W 5N40W 4N53W. SCATTERED
MODERATE CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE AXIS W
OF 32W. ISOLATED MODERATE IS WITHIN 120 NM EITHER SIDE BETWEEN
16W-23W.

...DISCUSSION...
GULF OF MEXICO...
COPIOUS MID AND UPPER LEVEL MOISTURE IS STREAMING ACROSS THE
CENTRAL AND WRN GULF...W OF 86/87W. THIS MOISTURE IS ASSOCIATED
WITH A DEEP LAYERED TROUGH THAT EXTENDS ACROSS THAT PORTION OF
THE AREA ANCHORED BY A LARGE LOW PRES SYSTEM CENTERED OVER WRN
KANSAS. A STRONG 100-120 KT UPPER LEVEL SUBTROPICAL JET EXISTS
BETWEEN THE DEEP TROUGH A LARGE RIDGE TO THE S IN THE EPAC. THIS
JET IS ALSO ADVECTING HIGH LEVEL MOISTURE ACROSS MEXICO INTO THE
WRN GULF. THE FOCUS OF THE DEEP MOISTURE IS IN THE AREAS OF
ENHANCED LOW-LEVEL LIFT. A COLD FRONT EXTENDS FROM CENTRAL
LOUISIANA TO THE WRN GULF NEAR 28N95W THEN BECOMES STATIONARY TO
AN ILL-DEFINED 1013 MB LOW ALONG THE SE TEXAS COAST NEAR 27N97W.
A WARM FRONT STRETCHES FROM THE FL/AL BORDER TO WRN TN. NUMEROUS
SHOWERS AND TSTMS ARE DETECTED ON THE 88-D'S IN THE WARM SECTOR
ACROSS THE NRN GULF COAST. DOPPLER RADAR IS ALSO DEPICTING A
NARROW LINE OF SCATTERED SHOWERS AND TSTMS NEAR THE TRAILING
COLD FRONT. IN THE ERN PORTION OF THE REGION...A MID-UPPER LEVEL
RIDGE IS SLOWLY SHIFTING E WITH THE AXIS OVER THE WRN BAHAMAS
ALONG 78W. MID AND UPPER LEVEL DRY AIR LIES ABOVE THE SE GULF
AND S/CENTRAL FLORIDA KEEPING CONDITIONS FAIRLY STABLE.
HOWEVER...THERE ARE SOME SCATTERED SHOWERS MOVING W ACROSS THE
LOWER FLA KEYS AND THE STRAITS. A RATHER BENIGN SFC TROUGH
EXTENDS ACROSS N AND CENTRAL FL MARKED BY A WIND SHIFT SEEN IN
SFC OBS. LOOKING AHEAD OVER THE NEXT FEW DAYS...MODELS HAVE
VARYING SOLUTIONS IN THE PATTERN BUT IT SEEMS LIKELY THAT A GOOD
DEAL OF MOISTURE WILL PUSH E ACROSS THE AREA. INCREASING NLY
WINDS TO GALE FORCE IS POSSIBLE IN THE WRN GULF LATE THIS
WEEKEND.

CARIBBEAN SEA...
THE UPPER LEVEL CUT OFF LOW OVER CUBA APPEARS TO HAVE OPENED
INTO A TROUGH WHICH EXTENDS ACROSS THE WRN CARIBBEAN FROM CUBA
TO COSTA RICA. UPPER LEVEL DIFFLUENCE HAS SPARKED A FEW SMALL
PATCHES OF ISOLATED TO SCATTERED SHOWERS N OF 15N BETWEEN
76W-83W. OTHERWISE...DRY AIR ALOFT IN PLACE IS PROVIDING QUIET
CONDITIONS W OF 70W. THE REMAINDER OF THE CARIB...E OF
70W...LIES ON THE N SIDE OF A VERY BROAD MID TO UPPER LEVEL
RIDGE CENTERED OVER FRENCH GUIANA. WLY UPPER LEVEL FLOW AND
BROKEN HIGH LEVEL CLOUDINESS IS THE RULE. TRADE WINDS HAVE
INCREASED A LITTLE WITH 15-20 KT WINDS COMMON. SLIGHTLY STRONGER
WINDS ARE IN THE CENTRAL CARIB. THIS FLOW WILL REMAIN MODERATE
TO STRONG AS THE SFC HIGH SLOWLY SHIFTS SE.

ATLANTIC OCEAN...
THE SUBTROPICAL AND TROPICAL ATLC OCEAN IS RELATIVELY QUIET WITH
ONLY WEAK FEATURES TO MENTION. STARTING IN THE SUBTROPICAL ATLC
FROM W TO E...A DEEP LAYERED RIDGE COVERS THE REGION W OF 65W. A
PAIR OF 1030 MB SFC HIGH REMAIN N OF THE AREA BUT WILL CONTINUE
MOVING TO THE SE LIKELY ENTERING THE NRN BOUNDARY TOMORROW.
MAINLY FAIR WEATHER LIES UNDER THE RIDGE EXCEPT FOR BROKEN
CLOUDINESS AND SCATTERED SHOWERS SPREADING FROM THE SE U.S. N OF
30N W OF 70W. THE PATTERN THEN FOLDS INTO A DEEP LAYERED TROUGH
WHICH COVERS A PORTION OF THE CENTRAL ATLC BETWEEN 40W-65W N OF
25N. AN ASSOCIATED COLD FRONT ENTERS THE AREA NEAR 32N44W AND
EXTENDS SW TO A WEAK 1018 MB LOW NEAR 24N57W. A SFC TROUGH
CONTINUES SW FROM THE LOW TOWARD THE N COAST OF PUERTO RICO.
DEEP MOISTURE APPEARS MAINLY CONTAINED WITHIN 120 NM E OF THE
BOUNDARY. PLENTY OF DRY AIR IN THE MID AND UPPER LEVEL IS BEING
ADVECTED BEHIND THE BOUNDARY. A STACKED RIDGE LIES TO THE E OF
THE TROUGH AND COVERS THE REGION BETWEEN 25W-40W. PLENTY OF DRY
AIR ALOFT IS ASSOCIATED WITH THE RIDGE. A SMALL SFC HIGH CENTER
IS ANALYZED AT 1027 MB NEAR 28N28W BUT THE MAIN HIGH CENTER IS
MUCH FURTHER TO NNE. THE ERN MOST PORTION IS UNDER AN UPPER
TROUGH WHICH COVERS THE ATLC E OF 25W N OF 20N. AN ASSOCIATED
WEAK 1018 MB LOW IS LOCATED NEAR 27N27W. THIS LOW IS ONLY A
LOW-LEVEL CLOUD SWIRL PRODUCING LITTLE...IF ANY...SHOWER
ACTIVITY. IN THE TROPICS...A VERY BROAD MID TO UPPER LEVEL RIDGE
IS CENTERED OVER FRENCH GUIANA. EXTENSIVE WLY FLOW AND BROKEN
CLOUDINESS COVERS THE REGION WITH CONVECTION CONFINED TO THE
ITCZ.

$$
CANGIALOSI




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