[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121747
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SUN 12 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...ITCZ...

ITCZ AXIS ALONG 10N14W 7N30W 9N55W 9N61W.  WIDELY SCATTERED
MODERATE WITHIN 75 NM OF 9N58W.  SCATTERED MODERATE CONVECTION
FROM 3.5N-6N BETWEEN 23W-30W AND WITHIN 45 NM OF LINE 8N29W
6.5N37W.  ISOLATED TSTMS FROM 6N-10N E OF 20W.  SECONDARY ITCZ S
OF AFRICA MIGHT BE CAUSING WIDELY SCATTERED MODERATE WITHIN 75
NM OF LINE 3N1W 3N6W.

...DISCUSSION...

GULF OF MEXICO/ATLANTIC W OF 63W/FAR NW CARIBBEAN...
DEEP MIDDLE/UPPER LEVEL TROUGH CONTINUES PLOWING EASTWARD ACROSS
THE W ATLC THIS AFTERNOON... NOW ALONG ABOUT 32N71W S TO THE
CENTRAL BAHAMAS.  MUCH COOLER/DRIER AIR HAS BEEN BROUGHT DOWN BY
AN ASSOCIATED COLD FRONT NOW LOCATED FROM JUST W OF BERMUDA THRU
CENTRAL CUBA INTO THE NW CARIBBEAN JUST S OF ROATAN INTO NW
HONDURAS.  FRONT IS MARKED BY AN INCREASE IN CLOUDINESS AND CAN
ALSO BE SEEN IN THE UPSLOPE CLOUDINESS/SHOWERS OVER CENTRAL
AMERICA.  1021 MB HIGH LIES OVER THE NW FLORIDA PENINSULA WITH
GENERALLY CLEAR SKIES W OF 88W N OF 22N WITH ONLY SOME PATCHY
STRATOCUMULUS ELSEWHERE ACROSS THE GULF.  SCATTERED TO BROKEN
LOW/MIDDLE CLOUDS ARE BEHIND THE FRONT IN THE W ATLC WITH THE
STRONG COLD AIR-ADVECTION OVER THE WARM OCEAN CAUSING THE CLOUD
INCREASE. ISOLATED TSTMS/SHOWERS ALONG THE FRONT N OF 25N WITHIN
120 NM WITH ONLY ISOLATED SHOWERS WITHIN 75 NM BEHIND THE FRONT
S OF 25N.  ANOTHER SHOT OF UPPER ENERGY SHOULD MOVE SOUTHWARD
FOR THE BEGINNING OF THE WEEK... BRINGING ANOTHER COLD FRONT
RAPIDLY INTO THE GULF BY TUE WITH WINDY CONDITIONS EXPECTED
ESPECIALLY IN THE W GULF.

REST OF THE CARIBBEAN SEA...
MOST SIGNIFICANT WEATHER FEATURE IS A WEAK LOW-LEVEL TROUGH JUST
N OF COLOMBIA ALONG ABOUT 74W.  ISOLATED SHOWERS ARE WITHIN 90
NM W OF THE TROUGH WITH WIDELY SCATTERED MODERATE CONVECTION
FROM 14N-16N BETWEEN 70W-73W.  OTHERWISE ZONAL FLOW COVERS THE
REGION AS WELL AS MODERATE/STRONG SUBSIDENCE.  SHOWER CHANCES
FOR MOST AREAS ARE LESS THAN AVERAGE EXCEPT FOR MAYBE THE FAR SE
CARIBBEAN NEAR TRINIDAD.  BROAD SURFACE TROUGH E OF THE
CARIBBEAN SHOULD MOVE CLOSER TO THE LESSER ANTILLES INCREASING
THE CHANCE OF RAIN ESPECIALLY FOR THE LEEWARD ISLANDS MON.

REMAINDER OF THE ATLANTIC OCEAN...
HIGH AMPLITUDE RIDGE IS IN THE CENTRAL ATLC ALONG 22N59W TO
32N52W AND SHOULD BUILD EASTWARD AS THE DEEP US E COAST TROUGH
REMAINS FOR THE WEEK.  TWO MID/UPPER LOWS ARE S OF THE RIDGE...
ONE CLOSER TO THE HIGH NEAR 26N45W AND THE OTHER IN THE DEEP
TROPICS NEAR 17N50W.  THE NORTHERN LOW IS SURROUNDED BY DRY AIR
WITH NO SIGNIFICANT IMPACT ON THE WEATHER.  HOWEVER THE SOUTHERN
LOW LIES CONNECTED TO A DEEP TROPICAL FEED OF MOISTURE...
PRODUCING WIDELY SCATTERED MODERATE CONVECTION FROM 16N-19N
BETWEEN 40W-52W.  BROAD SURFACE TROUGH IS ALONG 55W MOVING
BETWEEN 10N-20N MOVING W 15 KT WITH WIDELY SCATTERED SHOWERS
FROM 16N-20N BETWEEN 52W-60W.  FARTHER E...COLD FRONT IS JUST
ENTERING THE NW CANARY ISLANDS TO 24N25W THEN 24N40W.  SCATTERED
SHOWERS AND POSSIBLY A FEW TSTMS ARE WITHIN 60 NM OF THE FRONT
IN A FAVORABLE REGION OF DIVERGENCE ASSOCIATED WITH A POWERFUL
COLD LOW NEAR 35N21W.  BROKEN LOW/MIDDLE CLOUDS COVER THE
CENTRAL/E ATLC BEHIND THE FRONT E OF 45W... AS WELL AS HIGH
PRESSURE FROM A 1028 MB CENTER NEAR 34N43W.  THE REST OF THE
ATLC HAS BROAD UPPER RIDGING S OF 20N E OF 40W WITH SOME
DIVERGENT FLOW OVER THE ITCZ ENHANCING TSTMS NEAR 7N29W.

$$
BLAKE

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