Prognostic Meteorological Discussion
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FXCA20 KWBC 271538
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1138 AM EDT FRI MAR 27 2015

DISCUSSION FROM MARCH 27/00 UTC: HIGHLY AMPLIFIED SINUSOIDAL WAVE
PATTERN DOMINATES THE MID/UPPER LEVELS OF THE ATMOSPHERE...WITH A
RIDGE OVER THE CARIBBEAN/WESTERN ATLANTIC SEPARATING TWO TROUGHS.
THE WESTERNMOST DOMINATES THE CENTRAL-EASTERN USA AND THE GULF OF
MEXICO...WHILE THE ONE TO THE EAST BOUNDS BETWEEN 60W-30W INTO THE
TROPICAL ATLANTIC.

POLAR TROUGH TO THE WEST IS TO PUSH ACROSS THE EASTERN USA LATER
TODAY/EARLY SATURDAY MORNING. AS IT ENTERS THE WESTERN ATLANTIC IT
IS TO THEN LIFT OVER THE MID/UPPER LEVEL RIDGE TO THE EAST. UNDER
PRESSURE...THE RIDGE IS TO NEARLY COLLAPSE LATER ON SUNDAY
EVENING/EARLY MONDAY MORNING. BUT THE TROUGH IS TO ALSO WEAKEN AS
SHORT WAVE ENERGY SHEARS TO THE NORTHEAST. SUCCESSIVE SHORT WAVE
VORTICES ON THE SOUTHERN STREAM ARE TO THEN FOLLOW...TO TRACK
ACROSS NORTHERN STATES OF MEXICO-GULF INTO THE BAHAMAS-NORTHERN
CARIBBEAN ISLES DURING THE MEDIUM RANGE PERIOD. AT LOW LEVELS
ASSOCIATED FRONT EXTENDS ACROSS THE GULF-CENTRAL STATES OF MEXICO.
THROUGH FRIDAY EVENING THE FRONT SURGES ACROSS FLORIDA TO THE
YUCATAN-CAMPECHE SOUND/SOUTHERN VERACRUZ...WITH FRONTAL
NORTHERLIES OF 25-30KT TO ACCOMPANY THIS BOUNDARY. THROUGH
SATURDAY MORNING THE FRONT MOVES TO THE NORTHWEST
BAHAMAS...TRAILING ACROSS WESTERN CUBA TO THE NORTHERN YUCATAN.
LATER IN THE DAY IT MOVES TO THE CENTRAL BAHAMAS-EASTERN CUBA TO
THE YUCATAN. EARLY ON SUNDAY MORNING THE FRONT MOVES TO THE
SOUTHEAST BAHAMAS...WHILE TRAILING ACROSS CUBA/NORTHWEST CARIBBEAN
TO THE YUCATAN. ON SUNDAY EVENING THE FRONT REACHES THE TURKS AND
CAICOS...BUT AS THE UPPER TROUGH STARTS TO WEAKEN THE BOUNDARY IS
TO STALL ACROSS CUBA/NORTHWEST CARIBBEAN-NORTHERN YUCATAN.
BUILDING POLAR RIDGE OVER THE EASTERN USA IS TO SUSTAIN BRISK
EASTERLY TRADES ACROSS THE BAHAMAS-CUBA TO THE NORTHWEST
CARIBBEAN...FORECAST TO PEAK AT 20-25KT. THIS IS TO ALSO FAVOR A
PREFRONTAL SHEAR LINE THAT FORMS OVER CENTRAL/EASTERN CUBA BY
MIDDAY ON SATURDAY. THE SHEAR LINE THEN MOVES TO THE WINDWARD
PASSAGE-JAMAICA TO EASTERN NICARAGUA THROUGH EARLY MORNING HOURS
ON SUNDAY. LATER ON SUNDAY IT WILL MOVE ACROSS HISPANIOLA...WHERE
IT IS FORECAST TO STALL BEFORE BECOMING ILL DEFINED DURING THE DAY
ON MONDAY.

OVER MEXICO...THE FRONT AND STRONG FRONTAL NORTHERLIES ARE TO
FAVOR ORGANIZED CONVECTION ACROSS THE CENTRAL TO SOUTHERN
STATES...WITH RAINFALL AMOUNTS OF 15-30MM/DAY AND MAXIMA OF
40-80MM EXPECTED THROUGH SATURDAY MORNING. THIS SPREADS ACROSS
SOUTHERN MEXICO TO GUATEMALA-BELIZE THROUGH SUNDAY MORNING WITH
ACCUMULATION OF 15-20MM/DAY AND MAXIMA OF 35-70MM. ACROSS THE
BAHAMAS THIS IS TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-40MM. SIMILAR AMOUNTS ARE EXPECTED ACROSS
CENTRAL-EASTERN CUBA TO THE CAYMAN ISLES. OVER THE NORTHERN
YUCATAN EXPECT RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-40MM. OTHER ACTIVITY IS TO CLUSTER ACROSS THE CAYMAN ISLES ON
SATURDAY TO SUNDAY...WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA
OF 20-40MM. SHEAR LINE CONVERGENCE ACROSS NORTHERN HISPANIOLA IS
TO RESULT IN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15MM...WHILE OVER JAMAICA EXPECT ACCUMULATION OF 10-15MM/DAY AND
MAXIMA OF 20-40MM. ACROSS NORTHEAST HONDURAS TO EASTERN NICARAGUA
THIS IS TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15MM.

MID/UPPER LEVEL RIDGE...MEANWHILE...IS TO INITIALLY EXTEND FROM
THE CARIBBEAN TO THE WESTERN ATLANTIC...WITH 500 HPA AXIS TO
ANCHOR ON A CLOSED HIGH OVER THE DOMINICAN REPUBLIC. POLAR TROUGH
EXITING NORTH AMERICA WILL THEN SUSTAIN RAPID EROSION OF THIS
RIDGE FROM THE WEST...WITH AXIS OVER CENTRAL AMERICA/WESTERN
CARIBBEAN TO NEARLY COLLAPSE LATER ON SUNDAY. ALTHOUGH TO WEAKEN
TO THE WEST...WEAK RIDGE IS TO REMAIN OVER THE CENTRAL TROPICAL
ATLANTIC/EASTERN CARIBBEAN ISLANDS. AS THE RIDGE WEAKENS EXPECT
GRADUAL EROSION OF TRADE WINDS CAP DURING THE DAY ON
SATURDAY...MOST NOTICEABLE ACROSS SOUTHERN MEXICO-CENTRAL
AMERICA-CUBA-JAMAICA. ACROSS HISPANIOLA-PUERTO RICO A SLOWER
COLLAPSE OF THE CAP INVERSION IS EXPECTED LATER ON SUNDAY TO
MONDAY. ACROSS SOUTHERN HONDURAS-EL SALVADOR AND CENTRAL GUATEMALA
THE WEAKER INVERSION WILL ALLOW FOR DIURNAL HEATING DRIVEN
CONVECTION TO BECOME MORE ACTIVE AN BETTER ORGANIZED...WITH
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-25MM. OVER
COLOMBIA-NORTHWEST VENEZUELA...AS THE RIDGE/CAP
WEAKENS...EXPECTING AN INCREASE IN CONVECTION ALONG THE ANDEAN
REGION OF COLOMBIA TO NORTHWEST VENEZUELA. EARLY IN THE CYCLE
EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM.
THROUGH SUNDAY EVENING THIS INCREASES TO 15-20MM/DAY AND MAXIMA OF
30-60MM IN SCATTERED CONVECTION...WITH CELLS BUILDING NORTH INTO
THE DARIEN OVER EASTERN PANAMA.

EVOLVING MID/UPPER PATTERN IS TO ALSO REFLECT AT LOW LEVELS OF THE
ATMOSPHERE. EARLY IN THE CYCLE A BROAD SURFACE RIDGE IS TO
DOMINATE THE WESTERN ATLANTIC/NORTHERN CARIBBEAN ISLANDS. BUT THIS
IS TO GRADUALLY YIELD TO THE SURFACE FRONT...WITH PRESSURE
GRADIENT OVER THE NORTHERN CARIBBEAN ISLES EXPECTED TO SLACKEN
THROUGH MIDMORNING ON SATURDAY. EARLY IN THE CYCLE THIS IS TO
FAVOR TRADE WIND EASTERLIES OF 20-25KT...BUT THROUGH SUNDAY THEY
ARE TO DECREASE TO 10-15KT. EARLY ON THIS IS TO FAVOR GENERATION
OF STREAMERS AND TRADE WIND SHOWERS ACROSS THE ISLAND
CHAIN-NORTHEAST CARIBBEAN...BUT AS THE GRADIENT SLACKENS AND WINDS
WEAKEN EXPECT SEA/LAND BREEZES TO PREVAIL. THIS IS TO HAVE AN
IMPACT ACROSS CENTRAL PORTIONS OF HISPANIOLA AND THE
CORDILLERA/WESTERN INTERIOR PORTIONS OF PUERTO RICO. IN THIS AREA
EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM LATER
IN THE CYCLE.

OVER THE GUIANAS...UPPER LEVEL TROUGH IS TO TRAIL TO THE
SOUTH-SOUTHWEST INTO SURINAME-FRENCH GUIANA EARLY IN THE CYCLE.
THIS IS TO INTERACT WITH THE ITCZ TO THE SOUTH TO SUSTAIN AN
INCREASE IN MOISTURE CONVERGENCE. ACROSS FRENCH GUIANA TO EASTERN
SURINAME EXPECTING RAINFALL AMOUNTS OF10-15MM/DAY AND MAXIMA OF
20-35MM THROUGH SUNDAY MORNING...AND 05-10MM/DAY AND MAXIMA OF
15-20MM THEREAFTER. ACROSS GUYANA-WESTERN/CENTRAL SURINAME
EXPECTING RAINFALL AMOUNTS OF 00-05MM/DAY...INCREASING TO
05-10MM/DAY AND MAXIMA OF 15-20MM LATER ON SUNDAY TO MONDAY.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96        TYPE
NONE

CRAIG...TTMS (TRINIDAD AND TOBAGO)
NANDA...MDS (SURINAME)
DAVISON...WPC (USA)
$$





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