Prognostic Meteorological Discussion
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
220 PM EST WED DEC 07 2016

TROPICAL DISCUSSION FROM DEC 07/12 UTC: DEEPENING MID/UPPER LEVEL
TROUGH MOVES ACROSS THE NORTHERN USA LATER TODAY...WITH AXIS TO
RAPIDLY AMPLIFY ACROSS THE USA DURING THE DAY ON THURSDAY. THROUGH
FRIDAY EVENING THE TROUGH WILL MOVE TO THE WESTERN ATLANTIC WHILE
PRESSING AGAINST A WANING CELL OF THE SUBTROPICAL RIDGE TO THE
SOUTH. AT LOW LEVELS...MEANDERING FRONT EXTENDS ACROSS THE
NORTHWEST BAHAMAS-CENTRAL FLORIDA TO TAMAULIPAS. A NEW BOUNDARY
WILL APPROACH FROM THE NORTH...TO SURGE ACROSS THE CENTRAL USA TO
THE NORTHERN GULF OF MEXICO EARLY ON THURSDAY MORNING. THROUGH THE
DAY THIS WILL THEN MERGE WITH/REPLACE THE OLD BOUNDARY TO THE
SOUTH. ON FRIDAY MORNING THE FRONT WILL THEN MOVE TO THE NORTHWEST
BAHAMAS...WHILE TRAILING ACROSS WESTERN CUBA TO VERACRUZ IN
NORTHEAST MEXICO. A NORTHERLY WIND SURGE OVER THE WESTERN GULF OF
35-40KT ON FRIDAY TO SATURDAY WILL THEN DISPLACE THIS BOUNDARY
FARTHER SOUTH AND EAST...TO SURGE ACROSS THE BAHAMAS-CUBA TO THE
NORTHERN YUCATAN/SOUTHERN STATES OF MEXICO LATER ON FRIDAY/EARLY
SATURDAY MORNING. THE SURGING FRONTAL NORTHERLIES WILL THEN FAVOR
GENERATION OF A PREFRONTAL SHEAR LINE. EARLY ON FRIDAY MORNING THE
SHEAR LINE WILL EXTEND OVER THE CENTRAL BAHAMAS-WESTERN CUBA TO
THE GULF OF HONDURAS...WHILE ON FRIDAY AFTERNOON IT IS TO STRETCH
OVER THE SOUTHEAST BAHAMAS-EASTERN CUBA-JAMAICA TO COSTA
RICA/SOUTHEASTERN NICARAGUA. EARLY ON SATURDAY MORNING IT IS TO
MEANDER ACROSS HAITI TO THE SOUTHERN CARIBBEAN/COSTA RICA. AS IT
MEANDERS ALONG THE RIO BRAVO/NORTHEAST MEXICO THE FRONT IS TO ONLY
FAVOR LIGHT CONVECTION WITH ACCUMULATION OF 00-05MM/DAY. BUT AS IT
SURGES ACROSS TAMAULIPAS TO VERACRUZ ON THURSDAY THIS WILL SUSTAIN
RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 35-70MM. ON FRIDAY
THIS WILL INCREASE TO 20-40MM/DAY AND MAXIMA OF 75-125MM...WITH
LOCALLY HIGHER LIKELY OVER SOUTHERN VERACRUZ/NORTHERN OAXACA. OVER
THE NORTHWEST BAHAMAS EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY
AND MAXIMA OF 15MM ON WEDNESDAY TO THURSDAY...WHILE ON THURSDAY TO
FRIDAY EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-30MM. OVER WESTERN-CENTRAL CUBA AND ACROSS THE NORTHERN YUCATAN
THE FRONT WILL FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-20MM ON THURSDAY TO FRIDAY. OVER NORTHERN HONDURAS AND CENTRAL
GUATEMALA/SOUTHERN BELIZE THE SHEAR LINE WILL FAVOR RAINFALL
AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 35-70MM EARLY ON
FRIDAY...WHILE OVER THE SOUTHEAST BAHAMAS-EASTERN CUBA AND JAMAICA
EXPECTING RAINFALL AMOUNTS OF 00-05MM/DAY AND ISOLATED MAXIMA OF
10MM. OVER COSTA RICA/EASTERN NICARAGUA EXPECT RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM.

A 500 HPA HIGH OVER THE CENTRAL BAHAMAS ANCHORS A RIDGE OVER THE
WESTERN ATLANTIC-NORTHERN CARIBBEAN ISLES. AS THE AFOREMENTIONED
TROUGH MOVES EAST ACROSS THE USA IT IS TO PRESS AGAINST THE RIDGE
TO THE SOUTH. UNDER PRESSURE...THE HIGH WILL SLOWLY MIGRATE
EAST...REACHING THE CENTRAL ATLANTIC LATER ON FRIDAY. THE RIDGE...
MEANWHILE...IS FORECAST TO GRADUALLY WEAKEN FROM THE WEST.
INITIALLY...THE STRONG RIDGE PATTERN WILL FAVOR A CAP INVERSION
ACROSS THE NORTHERN CARIBBEAN ISLES. BUT AS THE RIDGE WEAKENS THE
CAP IS TO GRADUALLY RELAX ITS FOOTHOLD OVER THE ISLANDS...
ALLOWING FOR DEEPER MOISTURE TO POOL ALONG THE SURFACE FRONT AND
OTHER SURFACE FEATURES TO THE SOUTH. AT 850 HPA...MODELS SHOW
SIMILAR EVOLUTION TO UPPER LEVELS OF THE ATMOSPHERE...WITH NARROW
RIDGE TO EXTEND WEST-TO-EAST ACROSS THE NORTHERN CARIBBEAN ISLES.
THIS IS TO FAVOR LIGHT EASTERLY TRADES ACROSS THE NORTHERN
CARIBBEAN WHILE OVER THE SOUTHERN CARIBBEAN EXPECTING 850 HPA
WINDS OF 15-20KT. THIS PATTERN HOLDS OVER THE NEXT TWO DAYS...BUT
LATER DURING THE WEEKEND TIGHTENING PRESSURE GRADIENT IS TO FAVOR
A WIND SURGE ACROSS THE BASIN. THE STRONGER WINDS ARE TO FAVOR
GENERATION OF TRADE WIND SHOWERS ACROSS THE LESSER ANTILLES AND
ARE TO ALSO ENHANCE CONVERGENCE ALONG THE CARIBBEAN COASTAL PLAINS
OF NICARAGUA AND COSTA RICA.

ALSO...TO THE SOUTH OF THE UPPER LEVEL SUBTROPICAL RIDGE...THE
ANALYSIS SHOWS A SHORT WAVE TROUGH MEANDERING OFF THE COAST OF
VENEZUELA. OVER THE NEXT TWO DAYS THE UPPER LEVEL TROUGH IS TO
ANCHOR ON A MEANDERING LOW JUST NORTH OF ARUBA/CURACAO. THIS
WEAKENS TO AN OPEN TROUGH LATER ON FRIDAY. AS IT MEANDERS OVER THE
EASTERN CARIBBEAN THIS WILL ENHANCE CONVECTIVE DEVELOPMENT ALONG
THE COAST OF VENEZUELA AND THE ABC ISLES...WHERE WE EXPECT
RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. OVER NORTHWEST
VENEZUELA EXPECTING ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF
15-20MM OVER THE NEXT DAY...INCREASING TO 10-15MM/DAY AND MAXIMA
OF 20-35MM ON THURSDAY. OTHER CONVECTION TO THE SOUTH IS EXPECTED
ACROSS AMAZONIA IN SOUTHERN VENEZUELA... WHERE DIURNAL CONVECTION
IS TO SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-20MM. ON THE WESTERN PLAINS/ANDEAN REGION OF COLOMBIA EXPECTING
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM IN ISOLATED
TO SCATTERED CONVECTION. THROUGH FRIDAY THIS WILL INCREASE TO
10-15MM/DAY AND MAXIMA OF 20-40MM. ACROSS PANAMA/COSTA RICA EXPECT
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM AS THE EASTERN
PACIFIC ITCZ MEANDERS OVER THE ISTHMUS...INCREASING LATER IN THE
WEEK AS AN EASTERLY WAVE ENTERS THE SOUTHERN CARIBBEAN.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:

INITIAL   24     36     48     60     72     84     96    TYPE
55W      58W    61W    64W    67W    71W     74W    77W    EW

AN EASTERLY WAVE EXTENDS ALONG 55W TO 17N. LATER TODAY IT IS TO
PULL ACROSS GUYANA TO EASTERN VENEZUELA/WINDWARD ISLES...TO FAVOR
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. ON THURSDAY
THIS WILL INCREASE TO 10-15MM/DAY AND MAXIMA OF 20-40MM WHILE
BUILDING WEST ACROSS MARGARITA ISLAND/NORTHEAST COAST OF VENEZUELA
TO THE ABC ISLES. ON THE FRENCH/LEEWARD ISLES THIS IS TO THEN
FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. OVER
CENTRAL VENEZUELA THIS IS TO THEN FAVOR RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15-20MM...WITH MOST INTENSE OVER
AMAZONIA TO THE SOUTH. OVER PUERTO RICO AND THE DOMINICAN REPUBLIC
THIS IS NOW FORECAST TO TRIGGER RAINFALL AMOUNTS OF 00-05MM/DAY
AND MAXIMA OF 10MM ON THURSDAY...WHILE ON FRIDAY IT INCREASES TO
05-10MM/DAY AND MAXIMA OF 15MM. OVER NORTHWEST VENEZUELA TO
NORTHERN COLOMBIA EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-40MM EARLY ON FRIDAY...WITH SIMILAR AMOUNTS OVER
WESTERN COLOMBIA/PANAMA. AS IT PULLS ACROSS THE CENTRAL CARIBBEAN
THE 850 HPA WINDS WILL INCREASE TO 30-35KT LATER IN THE
WEEK...WHILE ACROSS VENEZUELA/EASTERN COLOMBIA THIS IS TO SUSTAIN
A 25-30KT NORTHERLY WIND SURGE THAT IS TO THEN SUSTAIN A GRADUAL
DRYING TREND LATER THIS WEEK/WEEKEND.

JIMENEZ...IMN (COSTA RICA)
MIRANDA...INAMEH (VENEZUELA)
DAVISON/GALVEZ...WPC (USA)

$$





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