Prognostic Meteorological Discussion
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734
FXCA20 KWBC 081915
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
214 PM EST THU DEC 08 2016

TROPICAL DISCUSSION FROM DEC 08/12 UTC: BROAD MID/UPPER LEVEL
TROUGH REACHES MAXIMUM AMPLITUDE ACROSS THE USA LATER TODAY...WITH
AXIS TO THEN MEANDER ACROSS THE EASTERN SEABOARD TO THE WESTERN
ATLANTIC LATER ON FRIDAY. AS IT EXITS THE USA THIS WILL PRESS
AGAINST A WANING CELL OF THE SUBTROPICAL RIDGE TO THE SOUTH. THE
TROUGH SUSTAINS A SURFACE FRONT THAT SURGES ACROSS THE GULF OF
MEXICO-FLORIDA PENINSULA. LATER TODAY IT IS TO THEN EXTEND ACROSS
THE NORTHWEST BAHAMAS...SOUTH FLORIDA TO TAMAULIPAS-COAHUILA IN
NORTHEAST MEXICO. A 35-45KT NORTHERLY SURGE ACROSS THE WESTERN
GULF DRIVES THE FRONT SOUTH TO VERACRUZ MEXICO EARLY ON
FRIDAY...AND LATER IN THE DAY IT IS TO EXTEND ACROSS THE
NORTHWEST/CENTRAL BAHAMAS-WESTERN CUBA TO THE GULF NORTH OF THE
YUCATAN TO VERACRUZ-NORTHERN MEXICO. UNDER INFLUENCE OF THE
SURGING FRONTAL NORTHERLIES A PREFRONTAL SHEAR LINE IS TO FORM
AHEAD OF THIS BOUNDARY...TO EXTEND OVER CENTRAL/WESTERN CUBA TO
THE GULF OF HONDURAS/GUATEMALA EARLY ON FRIDAY MORNING. ON FRIDAY
AFTERNOON IT MOVES TO THE SOUTHEAST BAHAMAS/TURKS AND
CAICOS-EASTERN CUBA-JAMAICA TO COSTA RICA/SOUTHEASTERN NICARAGUA.
THIS IS TO THEN MEANDER OVER THE CENTRAL/WESTERN CARIBBEAN THROUGH
SATURDAY EVENING...WHEN IT IS TO THEN BECOME ILL DEFINED AS THE
SURFACE FRONT LOSES ITS UPPER LEVEL SUPPORT AND NORTHERLIES WANE.

THE NORTHERLY WIND SURGE WILL TRIGGER ORGANIZED CONVECTION ACROSS
VERACRUZ AND THE SOUTHERN STATES OF MEXICO. OVER VERACRUZ
INITIALLY EXPECTING RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
35-70MM. ON FRIDAY...UNDER INFLUENCE OF A 35-45KT NORTHERLY JET
AND ANOMALOUSLY WARM SST OVER THE GULF...THIS WILL FAVOR HEAVY
CONVECTION ACROSS SOUTHERN VERACRUZ-OAXACA IN SOUTHERN MEXICO. IN
THIS AREA EXPECTING RAINFALL AMOUNTS OF 20-40MM/DAY AND MAXIMA OF
75-125MM. ON SATURDAY THIS WILL DECREASE TO 15-20MM/DAY AND MAXIMA
OF 30-60MM. OVER THE NORTHWEST BAHAMAS EXPECTING RAINFALL AMOUNTS
OF 10-15MM/DAY AND MAXIMA OF 20-30MM THROUGH SATURDAY. OVER
WESTERN-CENTRAL CUBA AND ACROSS THE NORTHERN YUCATAN THE FRONT
WILL FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM
THROUGH SATURDAY. 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. ON
SATURDAY THIS DECREASE TO 10-15MM/DAY AND MAXIMA OF 20-35MM. AS IT
ENTERS THE SOUTHEAST BAHAMAS-TURKS-EASTERN CUBA/JAMAICA ON FRIDAY
EVENING THE SHEAR LINE WILL FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY
AND MAXIMA OF 10MM. OVER THE SOUTHERN CARIBBEAN...AFFECTING
EASTERN NICARAGUA AND COSTA RICA EXPECTING RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 30-60MM ON FRIDAY TO SATURDAY
MORNING...WHILE DURING THE DAY ON SATURDAY EXPECTING RAINFALL
AMOUNTS FO 10-15MM/DAY AND MAXIMA OF 20-40MM.

A 500 HPA HIGH OVER THE SOUTHEAST BAHAMAS/TURKS AND CAICOS ANCHORS
A RIDGE OVER THE WESTERN ATLANTIC-NORTHERN CARIBBEAN ISLES. THE
DEEPENING POLAR TROUGH OVER NORTH AMERICA WILL PRESS AGAINST THIS
AXIS. RIDGE WILL THEN ERODE FROM THE WEST WHILE THE HIGH RELOCATES
NEAR 23N 58W LATER ON FRIDAY. AS THE RIDGE WEAKENS...TRADE WINDS
CAP OVER THE NORTHERN CARIBBEAN ISLES WILL LIFT. THIS WILL ALLOW
DEEPER MOISTURE TO POOL ALONG THE SURFACE FRONT AND OTHER SURFACE
FEATURES TO THE SOUTH. AT 850 HPA A NARROW/ELONGATED RIDGE WILL
EXTEND WEST-TO-EAST ACROSS THE NORTHERN CARIBBEAN ISLES. OVER THE
NORTHERN CARIBBEAN ISLES THIS IS TO FAVOR LIGHT EASTERLY
TRADES...WHILE OVER THE SOUTHERN CARIBBEAN EXPECTING 850 HPA WINDS
OF 15-20KT. THIS PATTERN HOLDS OVER THE NEXT COUPLE OF DAYS. LATER
DURING THE WEEKEND...TIGHTENING PRESSURE GRADIENT IS TO FAVOR A
WIND SURGE ACROSS THE BASIN. THE STRONGER WINDS ARE TO THEN 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.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:

INITIAL   24     36     48     60     72     84     96    TYPE
63W      66W    69W    72W    75W    78W    81W    85W     EW

A PROGRESSIVE EASTERLY WAVE EXTENDS ALONG 63W TO 17N IS
INTERACTING WITH AN UPPER LEVEL TROUGH OVER THE EASTERN
CARIBBEAN...FAVORING ORGANIZED CONVECTION. ACROSS THE VIRGIN
ISLES-EASTERN PUERTO RICO THIS IS TO ONLY FAVOR LIGHT CONVECTION
WITH ACCUMULATION OF 00-05MM/DAY AND MAXIMA OF 10MM. OVER WESTERN
PUERTO RICO AND PORTIONS OF HISPANIOLA EXPECTING RAINFALL AMOUNTS
OF 05-10MM/DAY AND MAXIMA OF 15MM. OVER THE FRENCH ISLES EXPECTING
ACCUMULATION OF 05-10MM AND MAXIMA OF 15-20MM THROUGH FRIDAY
MORNING...WHILE OVER THE WINDWARD ISLES-NORTHERN VENEZUELA/ISLA DE
MARGARITA AND THE ABC ISLES THIS IS TO FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-40MM. ON FRIDAY THIS INCREASES TO
15-20MM/DAY AND MAXIMA OF 25-50MM OVER THE ABC ISLES TO NORTHWEST
VENEZUELA. OVER SOUTHERN VENEZUELA TO EASTERN COLOMBIA THIS IS TO
THEN FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-20MM.ACROSS NORTHERN COLOMBIA THIS IS TO ALSO FAVOR RAINFALL
AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM ON SATURDAY. THIS IS
TO QUICKLY SPREAD ACROSS THE SOUTHERN CARIBBEAN TO COSTA
RICA-NICARAGUA LATER ON SUNDAY TO MONDAY. FURTHERMORE...AS IT
PULLS ACROSS THE CENTRAL CARIBBEAN THE GRADIENT IS TO
TIGHTEN...RESULTING IN AN 850 HPA WIND SURGE...WITH WINDS OF
30-35KT EXPECTED OVER THE SOUTHERN CARIBBEAN WHILE OVER THE
NORTHERN CARIBBEAN THE WINDS WILL PEAK AT 20-25KT.

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

$$





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