[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171747
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST MON DEC 17 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 6N11W 3N24W 1N37W 1N50W. SCATTERED
MODERATE CONVECTION IS FROM 2N-10N BETWEEN 48W-59W...ENHANCED BY
UPPER DIFFLUENT FLOW.

DISCUSSION...
GULF OF MEXICO...
COOL AND DRY AIRMASS IS IN PLACE ACROSS THE REGION TODAY...IN
THE WAKE OF A STRONG COLD FRONT WHICH IS NOW WELL E OF THE AREA
IN THE ATLC. BRISK N TO NE WINDS ARE BLOWING ACROSS THE E
GULF...WHERE THE PRES GRADIENT IS TIGHTEST BETWEEN A 1030 MB
HIGH OVER SRN MISSISSIPPI/ALABAMA AND THE FRONT. WINDS SHIFT
TOWARD THE E IN THE W GULF MODIFYING THE TEMPS THERE. SAT
IMAGERY SHOWS A FAIRLY THICK BLANKET OF STRATOCUMULUS
CLOUDS...INDICATIVE OF THE COOL STABLE AIRMASS. IN THE MID AND
UPPER LEVELS...STRONG ZONAL FLOW IS THE PATTERN. THIN HIGH LEVEL
CLOUDS ARE SPILLING INTO THE WRN HALF WHILE THE ATMOSPHERE
REMAINS VERY DRY ABOVE THE ERN HALF. LOOKING AHEAD...SFC HIGH
PRES WILL CONTINUE TO SHIFT E ALLOWING ELY FLOW TO DEVELOP
AREA-WIDE TOMORROW WHICH WILL WARM TEMPS BACK TO CLIMO.

CARIBBEAN SEA...
FRONTAL BOUNDARY IN THE W CARIB HAS SLOWED IN FORWARD SPEED
ANALYZED FROM CENTRAL CUBA TO HONDURAS AT 15 UTC. BROKEN
CLOUDINESS AND EMBEDDED SCATTERED SHOWERS ARE WITHIN 120 NM
BEHIND THE FRONT. COOL AIR HAS FILTERED WELL S INTO THE W CARIB
ADVECTED BY STRONG NLY FLOW. LOW TEMPS THIS MORNING WHERE AROUND
60 F ACROSS THE N PORTIONS OF THE YUCATAN PENINSULA. A FAINT
PREFRONTAL TROUGH IS AROUND 80W/81W S OF 18N NOTED IN A RECENT
QSCAT PASS AND BY A THIN AREA OF LOW-LEVEL CLOUDINESS. ELSEWHERE
E OF THE FRONT...MORE TYPICAL WEATHER PREVAILS SUPPORTED BY
MODERATE ELY TRADES WHICH ARE CARRYING PATCHES OF LOW TO MID
LEVEL CLOUDS AND EMBEDDED SHOWERS. THE ONLY ORGANIZED AREA AT
THE MOMENT IS OFF THE VENEZUELA COAST S OF 14N BETWEEN
62W-68W...AIDED BY SWLY FLOW ALOFT TO THE E OF A MID-UPPER LOW S
OF HISPANIOLA NEAR 17N69W. CONFLUENT FLOW ALOFT...BETWEEN THE
UPPER LOW AND AN UPPER HIGH NEAR 17N83W...IS PROVIDING A VERY
STABLE ENVIRONMENT ESPECIALLY N OF 15N BETWEEN 69W-75W.

ATLANTIC OCEAN...
STRONG COLD FRONT IS MOVING EWD IN THE W ATLC ANALYZED FROM JUST
W OF BERMUDA ACROSS THE BAHAMAS TO CENTRAL CUBA ALONG 32N66W
25N73W 21N78W THEN CONTINUING SWD IN THE W CARIBBEAN. SCATTERED
SHOWERS AND ISOLATED TSTMS ARE WITHIN 120 NM OF THE FRONT N OF
27N AND WITHIN 90 NM S OF 27N. MUCH COOLER AND DRIER AIRMASS IS
BEING ADVECTED IN BEHIND THE FRONT. DEEP LAYER RIDGING DOMINATES
THE WX PATTERN IN THE SUBTROPICS E OF THE FRONT TO ABOUT 30W OR
SO SUPPORTED BY A MID TO UPPER HIGH NEAR 29N52W AND A 1027 MB
SFC HIGH NEAR 36N42W. HOWEVER...A HIGHLY ELONGATED MID TO UPPER
TROUGH AND ASSOCIATED FRONTAL BOUNDARY IS INTERRUPTING THIS
RIDGING EXTENDING FROM 32N25W 25N43W THEN STATIONARY TO 31N49W.
CLOUDINESS AND POSSIBLE SHOWERS ARE WITHIN 120 NM OF THE FRONT.
THE SFC PATTERN IN THE E ATLC REMAINS RELAXED DUE TO THE
PRESENCE OF A WEAK 1016 MB LOW NEAR 22N22W...PRODUCING LITTLE
SENSIBLE WEATHER...AND THE AFOREMENTIONED COLD FRONT.

STRONG ZONAL FLOW ALOFT...OR JUST SOUTH OF WEST...LIES ABOVE
MOST OF THE TROPICS. WHILE THE JET CORE IS NOW E OF THE AREA
OVER N AFRICA THE RESIDUAL AXIS ALONG 15N43W 17N25W 20N16W IS
GENERATING CLOUDS AND EMBEDDED SCATTERED SHOWERS WITHIN 180 NM
S/SE OF THAT LINE. SCATTERED MODERATE CONVECTION HAS BEEN
PERSISTING N OF THE ITCZ FROM 2N-10N BETWEEN 48W-59W AIDED BY AN
UPPER DIFFLUENT PATTERN ASSOCIATED WITH AN ANTICYCLONE OVER
SOUTH AMERICA.

$$
CANGIALOSI




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