[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 100548
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST MON DEC 10 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
0515 UTC

...SPECIAL FEATURE...
THE AREA OF DISTURBED WEATHER ASSOCIATED WITH A BROAD AREA OF LOW
PRESSURE CENTERED ABOUT 370 NM EAST OF PUERTO RICO REMAINS
FAIRLY WELL-ORGANIZED...BUT SATELLITE IMAGES AND SURFACE
OBSERVATIONS SUGGEST THAT THIS SYSTEM HAS NOT DEVELOPED A CLOSED
CIRCULATION YET. THIS FEATURE IS MOVING WESTWARD NEAR 15 KT AND
IS PRODUCING HEAVY SQUALLS WITH GALE FORCE WINDS TO THE NORTH OF
THE SHOWER ACTIVITY. ENVIRONMENTAL CONDITIONS APPEAR TO BE
FAVORABLE FOR SOME DEVELOPMENT AND A TROPICAL OR SUBTROPICAL
STORM COULD FORM DURING THE NEXT 24 HOURS. INTERESTS IN THE
NORTHERN LEEWARD ISLANDS...THE VIRGIN ISLANDS...PUERTO RICO...
HISPANIOLA...AND THE EASTERN BAHAMAS SHOULD MONITOR THE PROGRESS
OF THIS SYSTEM. NUMEROUS MODERATE TO STRONG CONVECTION IS FROM
19N-21N BETWEEN 56W-61W. A GALE WARNING IS ALREADY IN EFFECT IN
THIS AREA. THE GFS COMPUTER MODEL HAS MOISTURE FROM THIS SYSTEM
SPREADING OVER THE NE CARIBBEAN TODAY.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N12W 4N25W 5N35W 4N54W. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 140 NM
SOUTH OF AXIS BETWEEN 19W-22W. SIMILAR CONVECTION IS FOUND
WITHIN 100 NM EITHER SIDE OF AXIS BETWEEN 35W-42W. UPPER
DIFFLUENCE IS ENHANCED THIS 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 AND MOSTLY
FAIR WEATHER. FRAGMENTS OF LOW LEVEL MOISTURE ARE OVER THE
CENTRAL GULF MAINLY N OF 24N ASSOCIATED WITH A MOIST ONSHORE
RETURN FLOW. BROAD UPPER-LEVEL RIDGE EXTENDS FROM THE CARIBBEAN
THROUGH THE YUCATAN CHANNEL TO OVER THE SE U.S. COVERING THE
ENTIRE GULF. MODERATE TO STRONG UPPER LEVEL SUBSIDENCE AND
IMPLIED DRY/STABLE AIR MASS IS NOTED WITHIN THE RIDGE AXIS.  .
OTHERWISE SKIES ARE CLEAR TONIGHT. LOOKING AHEAD...A COLD FRONT
WILL APPROACH E TEXAS WED...AND MOVE ACROSS THE NW CORNER OF THE
GULF LATE WED AND THURSDAY.

CARIBBEAN SEA...
BROAD UPPER RIDGE COVERS CENTRAL AMERICA AND THE W CARIBBEAN W
OF 80W ANCHORED BY AN UPPER HIGH LOCATED IN THE EPAC JUST SOUTH
OF PANAMA. BROAD UPPER TROUGH COVERS THE REMAINDER OF THE
CARIBBEAN WITH AN UPPER LOW SPINNING OVER PUERTO RICO AND THE
SURROUNDING COASTAL WATERS. UPPER DIFFLUENCE BETWEEN THIS LOW
AND AN UPPER RIDGE E OF THE WINDWARD ISLANDS IS ENHANCED
CONVECTION ASSOCIATED WITH THE SPECIAL FEATURE. STRONG NE TO E
SURFACE WINDS OF 20 TO 25 KT COVER THE CARIBBEAN DUE TO THE
TIGHT PRESSURE GRADIENT INDUCED BY THE STRONG SURFACE RIDGE
ACROSS THE ATLC. LOW LEVEL NELY FLOW AHEAD OF THE SPECIAL
FEATURE COMBINED WITH THE UPPER LOW MENTIONED ABOVE IS
GENERATING QUICK MOVING SHOWERS AND ISOLATED TSTMS OVER PUERTO
RICO AND HISPANIOLA. TYPICAL PATCHES OF LOW LEVEL MOISTURE DOT
THE REMAINDER OF THE BASIN. ISOLATED SHOWERS INLAND AND WITHIN
60 NM ALONG THE COAST OF PANAMA AND COSTA RICA DUE TO THE CLOSE
PROXIMITY OF THE ITCZ AXIS IN THE E PACIFIC REGION.

ATLANTIC OCEAN...
THE MOST SIGNIFICANT FEATURE ACROSS THE FORECAST AREA IS THE
BROAD AREA OF LOW PRESSURE CENTERED ABOUT 370 NM EAST OF PUERTO
RICO WITH A SFC TROUGH EXTENDING SOUTH ALONG 58W/59W. SEE
SPECIAL FEATURE ABOVE FOR MORE DETAILS. BROAD UPPER RIDGE COVERS
THE REMAINDER OF THE ATLC WITH A WEAKNESS ALONG THE SURFACE
TROUGH. IN THE UPPER LEVELS...BROAD UPPER RIDGE EXTENDING FROM
THE CARIBBEAN OVER THE GULF OF MEXICO COVERS THE FAR W ATLC W OF
75W. A SHORT WAVE TROUGH IS OVER THE W ATLC ALONG 70W/71W N OF
24N. AN UPPER-LEVEL RIDGE DOMINATES MOST OF THE CENTRAL ATLC.
A CUT-OFF UPPER LOW IS IN THE E ATLC NEAR 31N29W. AN UPPER HIGH
IS IN THE TROPICAL ATLC NEAR 2N38W COVERING THE AREA S OF 19N
BETWEEN THE WINDWARD ISLANDS AND THE AFRICAN COAST. A JET STREAM
BRANCH IS RIDING ON THE N PERIPHERY OF THIS ANTICYCLONE DRAWING
UPPER LEVEL MOISTURE FROM N SOUTH AMERICA NE AND E ACROSS THE
OCEAN.

$$
GR



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