[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 110559
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST TUE DEC 11 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
0530 UTC

...SPECIAL FEATURE...
THE AREA OF LOW PRESSURE CENTERED NEAR PUERTO RICO WAS UPGRADED
TO SUBTROPICAL STORM OLGA AT 11/0300 UTC. SUBTROPICAL STORM OLGA
IS CENTERED NEAR 18.5N 66.3W AT 0600 UTC OR ABOUT 15-20 NM
WEST-NORTHWEST OF SAN JUAN PUERTO RICO MOVING W AT 16 KT. OLGA
HAS STRENGTHENED WITH MAXIMUM SUSTAINED WIND SPEED NOW NEAR 45
KT WITH GUSTS TO 55 KT...AS INDICATED BY NOAA BUOY 41043. SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT2/WTNT22 KNHC AND THE NHC INTERMEDIATE PUBLIC ADVISORY
UNDER AWIPS/WMO HEADERS MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS.
THIS SYSTEM HAS CHANGED SIGNIFICANTLY FROM THIS AFTERNOON WHEN
SLY SHEAR WAS TAKING ITS TOLL EXPOSING THE LOW-LEVEL CENTER.
SINCE THEN...CONVECTION HAS WRAPPED AROUND THE W SIDE OF THE
CIRCULATION AFFECTING THE ISLAND OF PUERTO RICO. THESE RAINS
COULD PRODUCE LIFE-THREATENING FLASH FLOODS AND MUDSLIDES OVER
THE ISLAND. SIMILAR OR EVEN WORSE FLOOD POTENTIAL IS POSSIBLE
OVER THE MOUNTAINOUS ISLAND OF HISPANIOLA AS OLGA CONTINUES
WESTWARD. CURRENTLY...SCATTERED MODERATE CONVECTION IS WITHIN
200 NM N SEMICIRCLE. SCATTERED SHOWERS AND TSTMS ARE ELSEWHERE
FROM 18N-23N BETWEEN 58W-68W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N12W 6N21W 5N35W 2N45W 2N51W.
SCATTERED MODERATE CONVECTION IS FROM 7N-9N BETWEEN 31W-35W AND
FROM 5N-8N BETWEEN 40W-49W. ISOLATED MODERATE IS ELSEWHERE
WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 27W-43W.

DISCUSSION...
GULF OF MEXICO...
A MID TO UPPER LEVEL RIDGE REMAINS PARKED OVER AND JUST E OF THE
AREA ALLOWING THE FLOW ALOFT TO BE RATHER LIGHT AND THE
ATMOSPHERE FAIRLY STABLE. AT THE SFC...RIDGING EXTENDS SW INTO
THE GULF FROM A 1028 MB HIGH NEAR BERMUDA. MAINLY MODERATE E TO
SE WINDS ARE TRANSPORTING PATCHES OF LOW TO MID LEVEL CLOUDINESS
FROM THE ATLC ACROSS THE REGION. MOSAIC DOPPLER RADAR SHOWS
EMBEDDED SCATTERED SHOWERS OVER THE FLA STRAITS AND VERY LIGHT
ISOLATED ACTIVITY IN THE NW GULF. THE FRONT THAT WAS NEAR THE SE
TEXAS COAST EARLIER TODAY IS NOW PUSHING BACK INLAND AS LACKS
UPPER SUPPORT. THE NEXT FRONT...HOWEVER...SHOULD HAVE A
SUFFICIENT PUSH TO TRACK ACROSS THE AREA LATER THIS WEEK.

CARIBBEAN SEA...
NUMEROUS SQUALLS OF SHOWERS AND TSTMS ASSOCIATED WITH
SUBTROPICAL STORM OLGA IS ROTATING THROUGH THE ISLAND OF PUERTO
RICO AS NOTED IN SAN JUAN DOPPLER RADAR. THESE HEAVY RAINS COULD
CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES. SEE THE
SPECIAL FEATURE SECTION FOR MORE DETAILS. THE REMAINDER OF THE
REGION IS EXPERIENCING MOSTLY FAIR WEATHER BENEATH MODERATE TO
STRONG SUBSIDENCE ESPECIALLY BETWEEN THE UPPER LOW NEAR OLGA AND
AN ELONGATED RIDGE STRETCHING FROM COLOMBIA THRU THE YUCATAN
CHANNEL. TRADE WIND FLOW IS QUITE STRONG ACROSS THE REGION AS A
RECENT QSCAT PASS SHOWED A LARGE AREA OF 20-25 KT E TO NE WINDS
N OF 10N W OF 68W...EVEN TO 30 KT IN THE EXPOSED ATLANTIC
PASSAGES.

ATLANTIC OCEAN...
SUBTROPICAL STORM OLGA IS THE ONLY AREA OF CONVECTIVELY ACTIVE
WEATHER ACROSS THE ENTIRE ATLC DISCUSSION AREA...BESIDES FOR
THE ITCZ. SEE ABOVE FOR DETAILS. STACKED SFC AND MID LEVEL
RIDGING CONTROLS THE PATTERN IN THE W ATLC. TIGHT PRES GRADIENT
BETWEEN THE 1028 MB SFC HIGH NE OF BERMUDA AND OLGA IS PRODUCING
WINDS TO TROPICAL STORM FORCE WITHIN 175 NM N OF THE STORM
CENTER. DEBRIS STREAMS OF LOW TO MID LEVEL CLOUDINESS IS BEING
ADVECTED ACROSS THE W ATLC BY THE STRONG LOW-LEVEL FLOW. A BROAD
UPPER LOW CENTERED NEAR OLGA IS SPREADING DEBRIS HIGH LEVEL
MOISTURE WELL TO THE NE OF THE SYSTEM.

THE CENTRAL AND E ATLC IS VERY TRANQUIL WITH SFC RIDGING
DOMINATING THE PATTERN SUPPORTED BY THE BERMUDA HIGH AND A 1032
MB JUST N OF THE IBERIAN PENINSULA. THE MID AND UPPER FLOW IS
FAIRLY ZONAL ACROSS THIS PORTION OF THE ATLC AIDING IN THE
TRANQUILITY. THE ONLY PERTURBATION IN THIS PATTERN IS A WEAK
UPPER LOW CENTERED NEAR 28N26W. AN ASSOCIATED WEAK SFC TROUGH
LIES UNDERNEATH THE UPPER SYSTEM ALONG 27W FROM 25N-32N. IR
IMAGERY SUGGESTS A FEW SHOWERS WITHIN 90 NM OF THE UPPER LOW.

$$
CANGIALOSI



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