[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 200611
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST THU DEC 20 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0545 UTC

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 5N9W 3N25W 4N35W 2N45W AND INTO
SOUTH AMERICA NEAR THE EQUATOR AT 50W. CLUSTERS OF MODERATE TO
STRONG CONVECTION ARE WITHIN 50 NM EITHER SIDE OF THE AXIS
BETWEEN 17W-24W. SIMILAR CONVECTION IS WITHIN 150 NM N OF THE
AXIS BETWEEN 28W-33W. WIDESPREAD MODERATE TO STRONG CONVECTION
IS FROM 2N-6N BETWEEN 35W-45W. UPPER DIFFLUENCE IS ENHANCING
THIS CONVECTIVE ACTIVITY.

DISCUSSION...
GULF OF MEXICO...
HIGH PRES REMAINS IN CONTROL OF THE WEATHER PATTERN ACROSS THE
GULF GIVING THE AREA LIGHT TO MODERATE E TO SE WINDS WITH THE
RETURN FLOW BRINGING INCREASED MOISTURE TO THE W GULF.
UPPER-LEVEL OUTFLOW FROM CONVECTIVE ACTIVITY ALONG THE
TEXAS/LOUISIANA BORDER IS SPREADING OVER THE NW GULF. THE
REMAINDER OF THE GULF REMAINS TRANQUIL WITH PATCHES OF LOW LEVEL
CLOUDS UNDER STRONG SUBSIDENCE FROM AN UPPER RIDGE. A
SUBTROPICAL JET WITH CORE WINDS OF NEAR 120 KT IS RIDING ON THE
N PERIPHERY OF THE RIDGE FROM THE EPAC ACROSS N MEXICO AND THE N
GULF WATERS DRAWING UPPER-LEVEL MOISTURE ACROSS THE AREA. THE
NEXT COLD FRONT IS FORECAST TO ENTER THE REGION THIS WEEKEND.
STRONG WINDS AND HIGH SEAS WILL BUILD IN THE GULF FOLLOWING THE
FRONTAL PASSAGE.

CARIBBEAN SEA...
A SFC TROUGH STRETCHES FROM EASTERN CUBA ACROSS THE CAYMAN
ISLANDS TO NORTHERN BELIZE NEAR 18N88W. ASSOCIATED LOW CLOUDS
WITH EMBEDDED SHOWERS REMAIN OVER THE NW CARIBBEAN/GULF OF
HONDURAS. ALOFT...STRONG SUBSIDENCE AND DRY STABLE AIR DOMINATE
THE CENTRAL AND EASTERN CARIBBEAN. UPPER-LEVEL MOISTURE IS BEING
DRIVEN NWD ACROSS THE WINDWARD ISLANDS BETWEEN A SHORT-WAVE
TROUGH
OVER THE LESSER ANTILLES AND A RIDGE OVER THE TROPICAL ATLC.
SATELLITE IMAGERY SHOWS SHALLOW CONVECTION OVER THE ABC ISLANDS
AT THE BASE OF THE SHORT-WAVE TROUGH. MODERATE TO FRESH ELY
TRADE WINDS WILL CHANGE LITTLE THROUGH SATURDAY.

ATLANTIC OCEAN...
A SFC RIDGE EXTENDS FROM A 1024 MB SURFACE HIGH OVER GEORGIA
COVERING THE W ATLC. A BAND OF LOW LEVEL MOISTURE JUST CLIPS THE
DISCUSSION AREA N OF 30N ALONG 76W/77W. THIS MOISTURE IS
ASSOCIATED WITH A COLD FRONT WELL NORTH OF THE AREA. THE
SUBTROPICAL JET OVER THE NORTHERN GULF OF MEXICO CONTINUES TO
PUSH HIGH CLOUDS/MOISTURE OVER THE W ATLC. FARTHER EAST...A COLD
FRONT ENTERS THE REGION NEAR 31N45W AND STRETCHES SW TO
24N71W...THEN CONTINUES ACROSS THE BAHAMAS AND CENTRAL CUBA AND
INTO THE CARIBBEAN AS A SFC TROUGH. A BROKEN BAND OF MAINLY LOW
LEVEL CLOUDS WITH ISOLATED SHOWERS/THUNDERSTORMS IS BEHIND THE
FRONT. FAIR WEATHER STRATOCUMULUS CLOUDS ARE BEING TRANSPORTED
AROUND A 1028 MB SFC HIGH CENTERED NEAR 29N42W. AN UPPER-LEVEL
RIDGE DOMINATES THE CENTRAL ATLC. A DEEP-LAYERED TROUGH IS OVER
THE E ATLC. AN ASSOCIATED FRONTAL BOUNDARY EXTENDS OVER THE
CANARY ISLANDS TO 19N20W. UPPER WESTERLY ZONAL FLOW COVERS THE
TROPICAL ATLC.

$$
GR/RJW












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