Prognostic Meteorological Discussion
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FXCA20 KWBC 261709
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1209 PM EST WED NOV 26 2014

NOTE: TROPICAL DESK PRODUCTS WILL NOT BE AVAILABLE ON NOV 27-28.

DISCUSSION FROM NOVEMBER 26/00UTC: HIGH AMPLITUDE POLAR TROUGH
MOVES ACROSS THE EASTERN USA TO THE WESTERN ATLANTIC THROUGH
THURSDAY EVENING...MEANWHILE PRESSING AGAINST A WANING RIDGE TO
THE EAST. THROUGH FRIDAY MORNING THE RIDGE OVER THE WESTERN
ATLANTIC IS TO COLLAPSE...WITH BROAD TROUGH TO THEN EXTEND BETWEEN
50W-80W AND TO THE NORTH OF 20N. AS IT MOVES TO THE WESTERN
ATLANTIC A SUBTROPICAL JET MAXIMA IS TO LIE ALONG THE SOUTHERN
FRINGES OF THIS TROUGH...WITH AXIS WEST-TO-EAST ACROSS THE GREATER
ANTILLES. AT LOW LEVELS THIS SUSTAINS A POLAR FRONT THAT ENTERS
THE NORTHWEST BAHAMAS LATER THIS AFTERNOON. IT IS TO THEN TRAIL
ACROSS WESTERN CUBA TO THE GULF OF HONDURAS/ISLAS DE LA BAHIA.
FRONT IS TO BRIEFLY STALL...THEN SURGES EAST AND SOUTH AS ANOTHER
BOUNDARY APPROACHES FROM THE WEST. LATER ON THURSDAY THE FRONT
WILL MOVE TO THE CENTRAL BAHAMAS-CENTRAL CUBA TO BELIZE...REACHING
THE SOUTHEAST BAHAMAS/EASTERN CUBA-CAYMAN ISLES EARLY ON FRIDAY
MORNING. POLAR RIDGE IS TO THEN BUILD ACROSS THE GULF/SOUTHERN USA
THROUGH FRIDAY MORNING. THIS WILL HELP SUSTAIN A NORTHERLY FLOW
ACROSS CUBA-WESTERN/CENTRAL CARIBBEAN...WITH WINDS OF 25-30KT TO
CONVERGE ALONG THE NORTH COAST OF HONDURAS. STRONGER WINDS TO THE
SOUTH ARE EXPECTED ACROSS NICARAGUA TO THE EASTERN PACIFIC...TO
PEAK AT 40-45KT. THE TIGHTENING GRADIENT AND SURGING WINDS WILL
SUSTAIN A PREFRONTAL SHEAR LINE ACROSS THE CENTRAL BAHAMAS-CENTRAL
CUBA TO NORTHEAST NICARAGUA LATER THIS EVENING. THROUGH THURSDAY
EVENING IT WILL MOVE ACROSS THE TURKS AND CAICOS-EASTERN CUBA
WHILE TRAILING TO COSTA RICA. IT IS TO THEN MEANDER ACROSS THE
WINDWARD PASSAGE TO HISPANIOLA WHILE TRAILING TO COSTA RICA.

AS THE FRONT ENTERS THE NORTHWEST-CENTRAL BAHAMAS IT IS TO SUSTAIN
SCATTERED CONVECTION WITH RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM... WHILE OVER CUBA-SOUTHEAST BAHAMAS EXPECTING
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-30MM. MOST
INTENSE IS EXPECTED BETWEEN PUERTO BARRIOS GUATEMALA-LA CEIBA IN
HONDURAS...WHERE STRONG TOPOGRAPHICAL FORCING IS TO RESULT IN
RAINFALL AMOUNTS OF 50-75MM/DAY AND MAXIMA OF 150-250MM/DAY
THROUGH FRIDAY...AND MAXIMA OF 75-125MM ON SATURDAY. SHEAR LINE
RELATED CONVECTION IS TO THEN CLUSTER ACROSS SOUTHERN NICARAGUA TO
COSTA RICA...WHERE THIS IS TO SUSTAIN RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-40MM. OVER NORTHERN HAITI-THE CAYMAN
ISLANDS AND JAMAICA THIS IS TO RESULT IN RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM.

FURTHERMORE...DEEP POLAR TROUGH OVER THE GULF OF MEXICO/EASTERN
USA SUSTAINS THE NORTHWARD AMPLIFICATION OF THE PANAMANIAN LOW TO
THE CENTRAL CARIBBEAN...WHILE ANCHORING THE ITCZ OVER PANAMA-COSTA
RICA. BUT THIS WILL BE SHORT LIVED...AS RAPID INTENSIFICATION OF
THE NORTHERLY TRADES ACROSS THE BASIN WILL DISPLACE THE ITCZ SOUTH
INTO THE EASTERN PACIFIC. EARLY IN THE CYCLE THIS IS TO SUSTAIN
SCATTERED CONVECTION WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA
OF 20-40MM...BUT THIS DECREASES TO 05-10MM/DAY AND MAXIMA OF
15-20MM ON FRIDAY-SATURDAY. OVER WESTERN COLOMBIA/ANDEAN REGION
INITIALLY EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-25MM. THIS DECREASES TO MAXIMA OF 15-20MM IN ISOLATED TO
SCATTERED CONVECTION.

AS PREVIOUSLY INDICATED...POLAR TROUGH EXITING THE USA IS TO LIFT
OVER A WANING CELL OF THE SUBTROPICAL RIDGE TO THE EAST. THROUGH
THURSDAY EVENING PORTION OF THE RIDGE OVER THE WESTERN ATLANTIC IS
TO WEAKEN AS IT RELOCATES FARTHER TO THE EAST...WHILE OVER THE
CARIBBEAN BASIN AN OPEN/LOW AMPLITUDE RIDGE IS TO THEN REMAIN. AS
THE RIDGE FLATTENS/WEAKENS...TRADE WINDS CAP OVER THE
EASTERN-CENTRAL CARIBBEAN IS FORECAST TO WEAKEN...WITH DEEPER
MOISTURE TO GRADUALLY ADVECT ACROSS THE LESSER ANTILLES TO THE
EASTERN/ CENTRAL CARIBBEAN THROUGH FRIDAY EVENING/SATURDAY
MORNING. AT LOW LEVELS...A BROAD RIDGE OVER THE CENTRAL NORTH
ATLANTIC SUSTAINS A BRISK EASTERLY FLOW ACROSS THE ISLAND CHAIN TO
THE CARIBBEAN BASIN. UNDER PRESSURE FROM THE POLAR TROUGH TO THE
WEST THIS IS ALSO FORECAST TO GRADUALLY WEAKEN AS THE CYCLE
PROGRESSES...WITH STRONG EASTERLY TRADES EARLY IN THE CYCLE
FORECAST TO WEAKEN THROUGH THURSDAY MORNING. THE BRISK EASTERLY
TRADES ARE TO FAVOR GENERATION OF TRADE WIND SHOWERS AND LIGHT
CONVECTION ACROSS THE NORTHEAST CARIBBEAN ISLES. A GRADUAL
INCREASE IN ACTIVITY IS EXPECTED LATER INTO THE WEEKEND AS DEEPER
MOISTURE STARTS TO POOL ACROSS THE ISLAND CHAIN.

A DEEP TUTT TO THE EAST ORIGINATES ON A CLOSED LOW NEAR 20N
50W...WITH AXIS SOUTHWEST ACROSS THE LESSER ANTILLES TO VENEZUELA.
AS THE RIDGE TO THE WEST WEAKENS...THE TUTT IS TO RETROGRESS
ACROSS THE LESSER ANTILLES TO THE EASTERN CARIBBEAN...WITH CLOSED
LOW TO REPOSITION NEAR THE NORTHERN LEEWARD ISLES EARLY ON
THURSDAY MORNING. A FINGER OF THE SUBTROPICAL JET IS TO BOUND THE
NORTHERN PERIPHERY OF THE TROUGH...WITH ITS DIVERGENT LEFT EXIT
REGION (INDIRECT) TO MOVE JUST NORTH OF THE VIRGIN ISLES/PUERTO
RICO. ANOTHER JET IS TO BOUND THE SOUTHERN PERIPHERY OF THE
TROUGH...WITH ITS RIGHT ENTRANCE (DIVERGENT/DIRECT) OVER NORTHERN
GUYANA. EARLY ON FRIDAY THE TUTT WEAKENS AND RAPIDLY LIFTS TO THE
NORTHEAST WHILE MERGING INTO BROAD POLAR TROUGH OVER THE WESTERN
ATLANTIC. AT MID LEVELS THE TUTT ALOFT SUSTAINS A CLOSED
CIRCULATION THAT NEARS THE LESSER ANTILLES EARLY ON THURSDAY. THIS
IS TO ANCHOR A SHORT WAVE TROUGH OVER THE NORTHEAST CARIBBEAN
ISLES THROUGH THURSDAY EVENING. AS IT MEANDERS ACROSS THE
NORTHEAST CARIBBEAN ISLES...THIS IS TO FOCUS A SERIES OF WEAK
CYCLONIC VORTICES ACROSS THE FORECAST AREA... WITH BEST INFLOW OF
SHORT WAVE ENERGY EXPECTED LATER THIS AFTERNOON. ALTHOUGH UPPER
LEVEL DYNAMICS ARE TO BECOME MORE FAVORABLE AND CONDUCIVE TO
CONVECTION...MOISTURE IS TO REMAIN IN SHORT SUPPLY OVER THE NEXT
COUPLE OF DAYS. AS A RESULT...IT IS TO ONLY FAVOR SCATTERED
CONVECTION ACROSS THE VIRGIN ISLES TO PUERTO RICO WITH
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-20MM. OVER SOUTHERN
VENEZUELA...IN INTERACTION WITH THE NEAR EQUATORIAL TROUGH IT IS
TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-30MM...WHILE OVER NORTHERN GUYANA IN INTERACTION WITH THE ITCZ
EXPECTING ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-30MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96     TYPE
53W     56W    59W    62W    65W    68W     DISSIPATES  TUTT INDCD

TUTT ALOFT SUSTAINS INDUCED TROUGH IN THE EASTERLY TRADES WITH
AXIS NORTH-NORTHWEST ACROSS 53W. THIS ENTERS THE LESSER ANTILLES
BY MIDMORNING ON THURSDAY...INTO THE VIRGIN ISLES LATER IN THE
DAY. THIS IS TO SUSTAIN LIGHT CONVECTION WITH ACCUMULATION OF
00-05MM/DAY AND MAXIMA OF 10MM.

JN BAPTISTE...MS (SAINT LUCIA)
DAVISON...WPC (USA)
$$





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