[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 151136
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST MON DEC 15 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...THE ITCZ...
ITCZ IS CENTERED ALONG 8N13W 4N21W 3N40W 4N47W 3N51W. SCATTERED
MODERATE TO STRONG CONVECTION IS WITHIN 150 NM N AND 60 NM S OF
THE AXIS BETWEEN 20W-39W. SCATTERED MODERATE CONVECTION IS FROM
6N-9N BETWEEN 56W-58W.

...DISCUSSION...

GULF OF MEXICO...
STRONG WLY MID TO UPPER FLOW LIES OVER THE REGION ON THE N
PERIPHERY OF A HIGH CENTERED OVER THE NW CARIBBEAN. THIS FLOW IS
SPREADING PACIFIC HIGH LEVEL CLOUDINESS ACROSS THE N HALF OF THE
GULF WITH DRIER AIR PRESENT IN LIGHTER FLOW OVER THE S HALF...
CLOSER TO THE UPPER HIGH CENTER. IN THE LOWER LEVELS...A STRONG
1039 MB HIGH OVER THE WRN ATLC IS PRODUCING SE TO S 20-25 KT
OVER MUCH OF THE AREA. THIS STRONG MOIST LOW-LEVEL FLOW IS
PRODUCING PATCHY LOW-LEVEL CLOUDS WITH EMBEDDED SCATTERED
SHOWERS OVER THE NRN WATERS. A VERY STRONG COLD FRONT WILL
APPROACH THE TEXAS COAST BY MIDDAY BUT IT IS NOT EXPECTED TO
MAKE MUCH PROGRESS INTO THE GULF AS IT QUICKLY LOSES ITS UPPER
SUPPORT. HOWEVER...AN INCREASE IN SHOWERS AND TSTMS ARE LIKELY
OVER THE NW WATERS NEAR THE BOUNDARY LATER TODAY THROUGH TUE.

CARIBBEAN SEA...
ABUNDANT STABLE AIR ALOFT COVERS THE ENTIRE CARIBBEAN...DRIEST
OVER THE CENTRAL AND EASTERN PORTIONS WHERE THE UPPER FLOW IS
MOST CONFLUENT BETWEEN AN UPPER RIDGE OVER THE NW WATERS AND AN
UPPER TROUGH OVER THE W ATLC. NE TRADE WINDS HAVE INCREASED TO
20-25 KT AS THE STRONG ATLC HIGH HAS BUILT N OF THE AREA.
TYPICAL PATCHES OF LOW-LEVEL CLOUDS AND EMBEDDED QUICK MOVING
SHOWERS ARE BEING DRIVEN BY THE TRADES...BUT THE LARGE SCALE
SUBSIDENT ENVIRONMENT IS KEEPING THE MOISTURE SHALLOW. WINDS MAY
LIGHTEN OVER THE E CARIBBEAN TUE AND WED AS A SFC TROUGH MOVES
CLOSER TO THE AREA. OTHERWISE...LITTLE SIGNIFICANT CHANGES ARE
EXPECTED.

ATLANTIC OCEAN...
A COMPLEX UPPER TROUGH OVER THE CENTRAL ATLC IS PROVIDING
LIMITED SUPPORT FOR A WEAKENING QUASI-STATIONARY FRONT FROM
32N50W TO 24N72W. THE TIGHT PRESSURE GRADIENT BETWEEN THIS FRONT
AND A 1039 MB HIGH NEAR 39N62W IS PRODUCING N TO NE GALE FORCE
WINDS N OF 28N W OF FRONT TO 60W AND 20-25 KT ELSEWHERE W OF THE
FRONT. A SFC TROUGH IS BECOMING A LITTLE BETTER ORGANIZED JUST E
OF THE FRONT ALONG 52W N OF 22N. IR IMAGES REVEAL AN INCREASED
AREA OF CYCLONIC TURNING IN THE MID-LEVELS WITH ASSOCIATED
SCATTERED SHOWERS AND TSTMS N OF 26N BETWEEN 46W-56W. SIMILAR
ACTIVITY EXISTS FROM 19N-24N BETWEEN 42W-45W IN AN UPPER
DIFFLUENT ZONE. THIS SFC TROUGH WILL LIKELY GAIN VORTICITY FROM
THE WEAKENING FRONT AND POSSIBLY DEVELOP INTO A CLOSED LOW
TUE...ACCORDING TO MANY OF THE NWP MODELS. MODELS ARE IN GOOD
AGREEMENT IN SHOWING A TRACK TOWARD THE SW STEERED BY THE E
PERIPHERY OF A BUILDING MID-LEVEL RIDGE. FARTHER E...A SFC
TROUGH IS EVIDENT IN SCATTEROMETER AND BUOY DATA ALONG 51W/52W
FROM 8N-14N. HOWEVER...MUCH OF THE ASSOCIATED WEATHER IS SHEARED
WELL E OF THE TROUGH BY STRONG WLY WINDS. IN FACT...THIS FLOW IS
SPREADING WIDESPREAD MOISTURE ACROSS THE TROPICAL E ATLC AND
ENHANCING CONVECTION IN THE ITCZ AND N OF THE AXIS FROM 6N-11N
BETWEEN 39W-44W.

$$
CANGIALOSI





This weather bulletin was brought to you by:
www.nashvilleweather.net