[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 210601
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST TUE 21 DEC 2004

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N10W 8N40W 7N58W.  SCATTERED
MODERATE FROM 5N-8N BETWEEN 28W-33W.  ISOLATED MODERATE WITHIN
120 NM OF AXIS BETWEEN 15W-28W.

...DISCUSSION...

GULF OF MEXICO AND WEST ATLANTIC...
INITIAL COLD FRONT RESPONSIBLE FOR THE COLD TEMPERATURES OVER
THE SE UNITED STATES HAS STALLED ACROSS THE W ATLC FROM 32N59W
INTO N HAITI.  SECOND COLD FRONT HAS PAST BERMUDA AND IS NOW
FROM 32N61W TO THE FAR SE BAHAMAS NEAR THE TURKS/CAICOS ISLANDS
INTO SE CUBA.  MOSTLY BROKEN TO OVERCAST LAYER OF STRATOCUMULUS
STRETCHES BEHIND THE FRONT TO THE SOUTHEAST U.S. COAST OVER THE
W ATLC WATERS WITH MORE PARTLY CLOUDY CONDITIONS FROM THE
YUCATAN CHANNEL NWD TO THE CNTRL GULF.  FRONTS ARE LIKELY TO
MERGE LATER TODAY WITH THE SEPARATION BETWEEN THE BOUNDARIES
SHRINKING.  1026 MB HIGH OVER SE GEORGIA HAS BUILD ACROSS THE
ENTIRE GULF WITH RETURN FLOW MOISTURE MOVING NORTHWARD ACROSS SE
TEXAS AND LOUISIANA.  2ND COLD FRONT IS BEING SUPPORTED BY A
SHARP BUT WEAKENING UPPER LEVEL TROUGH WHICH HAS MOVED OFF THE
U.S. EAST COAST AND EXTENDS DOWN TO THE CENTRAL BAHAMAS.
CONVECTION HAS MOSTLY DISSIPATED ALONG THE FRONT BUT WIDELY
SCATTERED MODERATE REMAINS N OF 28N WITHIN 120 NM OF THE FRONT.

CARIBBEAN...
TWO FRONTS ARE ACROSS THE REGION... STATIONARY ONE ACROSS W
HAITI TO COSTA RICA AND A COLD FRONT FROM SE CUBA TO THE GULF OF
HONDURAS.  LITTLE WEATHER IS ASSOCIATED WITH EITHER BOUNDARY
EXCEPT FOR AN INCREASE IN CLOUDS WITH SOME ISOLATED SHOWERS.
NEARLY STATIONARY UPPER LEVEL HIGH IS CENTERED OVER NW VENEZUELA
NEAR 10N68W WITH A RIDGE EXTENDING NEWD THRU THE LEEWARD ISLANDS
INTO THE CNTRL ATLC TO 31N53W.  BROAD SW/W FLOW EXTENDS ACROSS
THE ENTIRE AREA WITH ONLY PATCHES OF MOISTURE COMING FROM
CONVECTION LOCATED S OF PANAMA. DESPITE THE MOSTLY DRY
ATMOSPHERE...A WLY MOVING SFC TROUGH NEAR THE ABC ISLANDS ALONG
10N67W 16N68W IS PRODUCING WIDELY SCATTERED MODERATE CONVECTION
IN A SMALL AREA FROM 12N-15N BETWEEN 66W-71W.

CENTRAL AND EASTERN ATLANTIC...
SOME OF THE STRONGEST ELY TRADES SINCE LAST WINTER ARE OVER THE
SUBTROPICAL ATLC E OF 50W THANKS TO A 1047 MB HIGH N OF THE
AZORES RIDGING DOWN INTO THE AREA ALONG 32N46W TO 23N60W.  THE
FLOW IS OVERLAID BY A DEEP MID/UPPER LEVEL TROUGH ALONG AN AXIS
FROM 31N37W 18N41W 5N50W WITH A BROAD LOW NEAR 20N40W.  STRONG
SUBSIDENCE IS OCCURRING ON THE WESTERN SIDE OF THE UPPER
TROUGH... KEEPING THE ITCZ RATHER WEAK AND ILL-DEFINED W OF 50W.
ON THE OTHER HAND...THE FLOW BECOMES SWLY AND DIVERGENT TO THE E
OF THE TROUGH WHICH IS SUPPORTING WIDELY SCATTERED MODERATE FROM
10N-16N BETWEEN 30W-40W AND WITHIN 150 NM OF 17.5N43W DUE TO
INSTABILITY FROM THE UPPER TROUGH.  BROAD SFC TROUGH IS LOCATED
WITHIN THIS GENERAL VICINITY ALONG 10N39W 21N40W AND IS MOVING
SLOWLY TO THE W.  IN THE FAR SE ATLC... MID/UPPER RIDGING
EXTENDS E OF 30W S OF 25N WITH PLENTY OF UPPER-LEVEL MOISTURE
FROM NEARBY ITCZ TSTMS AND THE DISTURBED WEATHER IN THE CENTRAL
ATLC.

$$
BLAKE

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