[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211135
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 5N8W 4N23W 7N40W 6N58W.  SCATTERED
MODERATE FROM 4N-7N BETWEEN 25W-30W.  ISOLATED TSTMS FROM 1N-5N
E OF 25W.

...DISCUSSION...

GULF OF MEXICO AND WEST ATLANTIC...
SLY WINDS HAVE TAKEN OVER MOST OF THE GULF WATERS AHEAD OF THE
NEXT COLD FRONT SCHEDULED TO MOVE INTO THE AREA BY WED.
SCATTERED LOW CLOUDS DOT THE REGION WITH CLOUDS THICKENING IN
THE W GULF ALONG WITH WINDS PICKING UP TO 20 KT OVER THE CENTRAL
AND NW GULF.  WEAK MID/UPPER SHORTWAVE MOVING ACROSS THE NE GULF
HAS SPREAD HIGH CLOUDINESS OVER FLORIDA AND GENERALLY KEPT
TEMPERATURES A BIT HIGHER THAN FREEZING OVER MOST OF S AND
CENTRAL FLORIDA S OF ORLANDO.  PAIR OF FRONTS RESPONSIBLE FOR
THE COLD TEMPERATURES OVER THE SE UNITED STATES ARE ACROSS THE W
ATLC WITH THE EASTERNMOST FRONT WEAKENING FROM 32N56W INTO N
HAITI.  HOWEVER SECOND COLD FRONT IS CLOSE BEHIND... NOW FROM
32N60W TO EXTREME SE CUBA.  LAYER OF BROKEN TO OVERCAST
STRATOCUMULUS CLOUDS STRETCHES BEHIND THE FRONT TO THE COAST OF
THE SE USA.  1027 MB HIGH OVER E GEORGIA HAS BUILD ACROSS THE
ENTIRE GULF AND IS MOVING OFFSHORE IN ATLC WATERS.   W ATLC COLD
FRONTS ARE BEING SUPPORTED BY A DEPARTING UPPER LEVEL TROUGH
FROM 32N60W TO 26N69W.  WIDELY SCATTERED MODERATE CONVECTION
REMAINS ALONG THE FRONT N OF 26N WITHIN 120 NM OF THE FRONT.

CARIBBEAN...
TWO DYING STATIONARY FRONTS ARE ACROSS THE REGION... ONE ACROSS
W HAITI TO COSTA RICA AND ANOTHER FROM SE CUBA TO THE GULF OF
HONDURAS.  LITTLE WEATHER IS ASSOCIATED WITH EITHER EXCEPT FOR
AN INCREASE IN CLOUDS WITH ISOLATED SHOWERS WITH THE
SOUTHERNMOST FEATURE. NEARLY STATIONARY UPPER LEVEL HIGH IS
CENTERED OVER NW VENEZUELA NEAR 10N68W WITH A RIDGE EXTENDING NE
THRU THE LEEWARD ISLANDS INTO THE CNTRL ATLC TO 31N51W.  BROAD
DRY SW/W FLOW EXTENDS ACROSS THE ENTIRE AREA WITH ONLY PATCHES
OF MOISTURE COMING FROM CONVECTIVE BLOWUP CLOUDS S OF PANAMA.
DESPITE THE MOSTLY DRY ATMOSPHERE...A WEAK SFC TROUGH NEAR THE
ABC ISLANDS ALONG IS PRODUCING WIDELY SCATTERED MODERATE
CONVECTION IN A SMALL AREA FROM 12N-15N BETWEEN 67W-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 TIGHT PRESSURE GRADIENT
FROM A 1043 MB HIGH N OF THE AZORES RIDGING DOWN INTO THE AREA
ALONG 31N46W TO 25N59W.  THE SURFACE FLOW IS TOPPED BY A
MID/UPPER LEVEL LOW CENTERED NEAR 22N42W WITH TROUGHING
EXTENDING S TO 5N49W COVERING A GOOD CHUNK OF THE CENTRAL ATLC.
STRONG SUBSIDENCE IS OCCURRING ON THE WESTERN SIDE OF THE UPPER
TROUGH... PREVENTING MANY ITCZ SHOWERS FROM FORMING. E OF THE
LOW/TROUGH...UPPER FLOW IS DIVERGENT... SUPPORTING WIDELY
SCATTERED MODERATE FROM 11N-18N BETWEEN 30W-40W AND FROM 15N-22N
BETWEEN 35W-45W DUE TO COLD AIR INSTABILITY ALOFT FROM THE UPPER
TROUGH.  BROAD SFC TROUGH IS LOCATED WITHIN THIS GENERAL
VICINITY ALONG 40W BETWEEN 10N AND 23N AND IS MOVING 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
AGITATED WEATHER IN THE CENTRAL ATLC.

$$
BLAKE

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