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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1915Z Dec 17, 2014)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
215 PM EST WED DEC 17 2014

DISCUSSION FROM DECEMBER 17/00UTC: AT 500 HPA...MID LEVEL RIDGE IS
TO RAPIDLY STRENGTHEN ITS FOOTHOLD ACROSS THE CENTRAL/EASTERN
CARIBBEAN WHILE BUILDING FROM WEST-TO-EAST ACROSS THE BASIN. RIDGE
IS TO ORIGINATE OVER SOUTHERN MEXICO/NORTHERN CENTRAL
AMERICA...AND THROUGH THURSDAY MORNING IT IS TO AMPLIFY ACROSS THE
CARIBBEAN BASIN TO NORTHERN SOUTH AMERICA. THIS IS TO THEN BECOME
DOMINANT SYNOPTIC SCALE FEATURE OVER THE CARIBBEAN THROUGH THE
MEDIUM RANGE PERIOD. AS IT BUILDS...RIDGE IS TO STRENGTHEN TRADE
WINDS CAP...LEADING TO RAPID EROSION OF AVAILABLE WATER. DRYING
TREND IS TO START OVER THE NORTHERN CARIBBEAN EARLY IN THE
CYCLE...AND IT IS TO RAPIDLY EXPAND INTO THE SOUTHERN CARIBBEAN TO
NORTHERN SOUTH AMERICA. THE RIDGE ALOFT IS TO REFLECT QUITE WELL
AT LOW LEVELS OF THE ATMOSPHERE. EARLY IN THE PERIOD IT IS TO
LIMIT TO THE GULF OF MEXICO-BAHAMAS...BUT THROUGH FRIDAY MORNING
IT IS TO MIGRATE EAST INTO THE WESTERN ATLANTIC. ACROSS THE
NORTHERN CARIBBEAN ISLES THIS IS TO GENERALLY FAVOR FAIR WEATHER
CONDITIONS OVER THE NEXT FEW DAYS.

ACROSS THE BASIN...THE LOW LEVEL RIDGE IS TO SUSTAIN BRISK
EASTERLY WINDS THAT ARE TO CONVERGE ALONG A SHEAR LINE OVER THE
CENTRAL/SOUTHERN CARIBBEAN. THROUGH THURSDAY EVENING THE SHEAR
LINE IS TO BECOME ILL DEFINED. MEANWHILE...THIS IS TO ENHANCE
MOISTURE CONVERGENCE ACROSS JAMAICA TO FAVOR RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM. THROUGH THURSDAY EVENING EXPECTING
RAPID EROSION OF AVAILABLE WATER AS THE TRADE WINDS CAP
STRENGTHENS ACROSS THE BASIN. OVER COSTA RICA/EASTERN NICARAGUA
THIS IS TO SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-20MM THROUGH THURSDAY MORNING. ON THURSDAY TO FRIDAY MOST
ACTIVE IS TO CONVERGE ACROSS EASTERN NICARAGUA/NORTHEAST HONDURAS
WITH ACCUMULATION OF 05-10MM/DAY AND WIDELY ISOLATED MAXIMA OF
15MM.

AS THE MID LEVEL RIDGE HOLDS OVER THE CARIBBEAN BASIN...SHORT WAVE
PERTURBATIONS ARE TO STREAM TO THE NORTH...WITH A FAIRLY STRONG
SHORT WAVE TROUGH TO MOVE ACROSS NORTHERN MEXICO TO TEXAS LATER ON
THURSDAY. THIS CONTINUES TO THE CENTRAL USA LATER ON FRIDAY. AS IT
ENTERS NORTHWEST MEXICO THIS IS TO ENHANCE MOISTURE TRANSPORT
ACROSS NORTHERN PORTIONS OF BAJA CALIFORNIA-NORTHERN
SONORA/CHIHUAHUA...WHERE WE EXPECT RAINFALL AMOUNTS OF 00-05MM/DAY
AND MAXIMA OF 10MM. AS IT ENTERS THE CENTRAL USA THIS IS TO THEN
TRIGGER CYCLOGENESIS EARLY ON FRIDAY...WITH ASSOCIATED FRONT TO
MOVE SOUTH ACROSS THE RIO BRAVO TO THE NORTHEAST STATES OF MEXICO
LATER IN THE DAY. THROUGH SATURDAY MORNING THE FRONT IS TO
CONTINUE INTO THE NORTHWEST GULF-TAMAULIPAS MEXICO...WHERE IT IS
TO MEANDER THROUGH SATURDAY EVENING. ACROSS NORTHEAST MEXICO THIS
IS TO THEN FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF
10MM. FURTHERMORE...THE DEEPENING POLAR TROUGH IS TO SUSTAIN AN
INDUCED/INVERTED TROUGH ACROSS THE YUCATAN PENINSULA. THIS IS TO
ALSO ENHANCE MOISTURE CONVERGENCE ACROSS BELIZE-QUINTANA ROO IN
THE YUCATAN TO SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA
OF 15-20MM.

SOUTH OVER THE CARIBBEAN...EVOLVING MID LEVEL RIDGE PATTERN IS TO
ALSO FAVOR EROSION OF AVAILABLE WATER ACROSS SOUTHERN CENTRAL
AMERICA-NORTHERN SOUTH AMERICA. ACROSS PANAMA-COSTA RICA ACTIVITY
WANES THROUGH FRIDAY MORNING...WITH RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM IN DIURNAL CONVECTION. ITCZ
CONVERGENCE OVER COLOMBIA WILL LIMIT TO EJE CAFETERO/THE CAUCA
VALLEY...WITH RAINFALL AMOUNTS OF 05-10MM/DAY AND ISOLATED MAXIMA
OF 15-20MM. THE ATLANTIC ITCZ...MEANWHILE...IS TO MEANDER SOUTH
ACROSS THE SOUTHERN GUIANAS TO VENEZUELA...WITH MOST ACTIVE
CONVECTION ACROSS AMAPA IN BRASIL-THE SOUTHERN GUIANAS TO AMAZONIA
IN VENEZUELA. IN THIS AREA EXPECTING RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM THROUGH FRIDAY MORNING...AND
05-10MM/DAY WITH  MAXIMA OF 15MM ON FRIDAY TO SATURDAY.

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)