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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1917Z Dec 11, 2014)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
217 PM EST THU DEC 11 2014

DISCUSSION FROM DECEMBER 10/00UTC: WEST OVER THE DOMAIN...A
MID/UPPER LEVEL SHORT WAVE TROUGH ON THE SOUTHERN STREAM IS TO
SLOWLY LIFT ACROSS NORTHWEST MEXICO THROUGH FRIDAY EVENING. AS IT
MEANDERS OVER THE EASTERN PACIFIC THIS IS TO INTERACT WITH THE
ITCZ TO THE SOUTH...DRAWING A PLUME OF TROPICAL MOISTURE NORTHWARD
ACROSS THE SOUTHWEST STATES OF MEXICO. AS MOISTURE CONVERGES OVER
THE SIERRA MADRE DEL SUR AND OCCIDENTAL THIS IS TO FAVOR ISOLATED
TO SCATTERED LIGHT CONVECTION...WITH RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM EXPECTED THROUGH SATURDAY.

BROAD CELL OF THE SUBEQUATORIAL RIDGE DOMINATES THE FLOW ACROSS
CENTRAL AMERICA-CARIBBEAN/NORTHERN SOUTH AMERICA. THE 250 HPA
RIDGE IS TO ANCHOR ON A CLOSED HIGH OVER THE SOUTHERN
CARIBBEAN/PANAMA-COSTA RICA...WHILE SPANNING BETWEEN CENTRAL
AMERICA/SOUTHERN MEXICO AND THE EASTERN CARIBBEAN ISLANDS. AT 500
HPA A HIGH SOUTH OF HISPANIOLA IS TO ANCHOR THIS RIDGE. AS IT
EXTENDS ACROSS THE CARIBBEAN THIS IS TO SUSTAINS A STRONG TRADE
WINDS CAP ACROSS THE NORTHERN CARIBBEAN ISLES-LESSER ANTILLES AND
PORTIONS OF CENTRAL AMERICA. STRONG RIDGE PATTERN IS FORECAST TO
HOLD OVER THE NEXT FEW DAYS...WITH AMPLIFYING POLAR TROUGH OVER
THE WESTERN ATLANTIC TO PRESS AGAINST THIS AXIS LATER DURING THE
WEEKEND.

EARLY IN THE CYCLE BROAD MID/UPPER LEVEL POLAR TROUGH IS TO
CONFINE TO THE NORTHWEST ATLANTIC/NORTHEAST USA. AS A SECONDARY
VORTEX ROUNDS THE BASE OF THE TROUGH LATER ON FRIDAY IT WILL START
TO AMPLIFY ACROSS THE SOUTHEAST USA...AND THROUGH SUNDAY EVENING
IT IS EXPECTED TO DEEPEN TO THE NORTHERN CARIBBEAN ISLES. AS THE
TROUGH DEEPENS AND THE SUBEQUATORIAL RIDGE TO THE SOUTH
WEAKENS...EXPECTING TRADE WINDS CAP OVER HISPANIOLA-PUERTO RICO TO
ALSO WEAKEN LATER DURING THE WEEKEND/EARLY NEXT WEEK. AT LOW
LEVELS...A MEANDERING FRONT EXTENDS ACROSS THE SOUTHEAST
BAHAMAS-EASTERN CUBA-NORTHERN YUCATAN PENINSULA. THROUGH FRIDAY
MORNING THE FRONT MEANDERS OVER THE CENTRAL BAHAMAS-CENTRAL CUBA
WHILE TRAILING TO THE NORTHERN YUCATAN. THIS IS TO REMAIN NEARLY
STATIONARY THROUGH SATURDAY MORNING. EARLY IN THE DAY...A
SECONDARY FRONT IS TO SURGE ACROSS THE EASTERN USA TO THE
NORTHWEST BAHAMAS-WESTERN CUBA. THROUGH SUNDAY MORNING IT MERGES
WITH/REINFORCES THE OLD BOUNDARY TO THE SOUTH...AND LATER IN THE
DAY IT WILL MOVE TO NORTHERN HISPANIOLA-SOUTH OF CUBA INTO THE
NORTHWEST CARIBBEAN. EARLY IN THE CYCLE THE MEANDERING FRONT IS TO
SUSTAIN LIGHT CONVECTION ACROSS THE SOUTHEAST BAHAMAS-EASTERN
CUBA...WITH ACCUMULATION OF 00-05MM/DAY AND MAXIMA OF 10MM. AS IT
MERGES WITH THE NEW APPROACHING FRONT...AND MESO-SYNOPTIC
CONDITIONS BECOME MORE FAVORABLE/CONDUCIVE TO DEEP
CONVECTION...EXPECTING A RAPID INCREASE ACROSS NORTHERN
HISPANIOLA-PUERTO RICO...WITH RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15MM ON SATURDAY TO SUNDAY.

ALSO AT LOW LEVELS...THE MEANDERING FRONT SUSTAINS A PREFRONTAL
SHEAR LINE ACROSS HAITI-COSTA RICA. THROUGH FRIDAY MORNING THIS IS
TO MEANDER WEST TO THE SOUTHEAST BAHAMAS-EASTERN
CUBA-JAMAICA-EASTERN NICARAGUA...WHERE IT IS TO REMAIN THROUGH
MIDDAY ON SATURDAY. BUT AS A POLAR RIDGE BUILDS TO THE WEST AND
NORTHERLIES INTENSIFY THE SHEAR LINE IS TO THEN MOVE EAST ACROSS
HISPANIOLA-SOUTHERN NICARAGUA/COSTA RICA LATER ON SATURDAY.
THROUGH SUNDAY EVENING THE SHEAR LINE WILL THEN MOVE ACROSS PUERTO
RICO TO NORTHERN COLOMBIA/LA GUAJIRA PENINSULA. ACROSS NORTHERN
HAITI THIS IS TO FAVOR LIGHT TO MODERATE CONVECTION WITH
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15MM. AS IT MOVES TO
PUERTO RICO EXPECTING ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF
15-20MM LATER ON SUNDAY. OVER COSTA RICA/SOUTHERN NICARAGUA
INITIALLY EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-35MM. THROUGH MIDDAY ON FRIDAY THIS INCREASES TO 10-15MM/DAY
AND MAXIMA OF 20-45MM. THIS IS TO PERSIST THROUGH SUNDAY MORNING.

THE ITCZ OVER THE EASTERN PACIFIC EXTENDS ALONG 07N/08N TO THE
NEAR EQUATORIAL TROUGH OVER NORTHERN COLOMBIA/NORTHWEST VENEZUELA.
AS IT MEANDERS OVER NORTHWEST SOUTH AMERICA THIS IS TO FAVOR
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. THE
ATLANTIC ITCZ...MEANWHILE...EXTENDS WEST ALONG 05N TO THE NORTHERN
GUIANAS INTO THE NEAR EQUATORIAL TROUGH OVER EASTERN VENEZUELA. A
MEANDERING MID/UPPER LEVEL TROUGH OVER THE CENTRAL ATLANTIC IS TO
ENHANCE CONVECTION ACROSS AMAPA IN BRASIL TO NORTHERN FRENCH
GUIANA...TO RESULT IN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA
OF 20-30MM THROUGH FRIDAY MORNING...AND 05-10MM/DAY WITH MAXIMA OF
15-20MM THEREAFTER. OVER SURINAME-NORTHERN GUYANA...IN A MID/UPPER
CONVERGENT PATTERN EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM THROUGH FRIDAY MORNING...AND 00-05MM/DAY WITH
WIDELY ISOLATED MAXIMA OF 10MM THEREAFTER.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96     TYPE

NONE.

JN BAPTISTE...MS (SAINT LUCIA)
NANDA...MDS (SURINAME)
DAVISON...WPC (USA)