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Tropical Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1911Z Feb 27, 2015)
 
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
211 PM EST FRI FEB 27 2015

DISCUSSION FROM FEBRUARY 27/00UTC: MEANDERING MID/UPPER LEVEL
TROUGH REMAINS OVER NORTH AMERICA. THROUGH SATURDAY EVENING THE
TROUGH IS TO RAPIDLY PULL AS A RIDGE BUILDS TO THE SOUTH. AT LOW
LEVELS...THE ASSOCIATED SURFACE FRONT IS TO MEANDER OVER THE
NORTHWEST BAHAMAS-SOUTH FLORIDA/KEYS TO THE SOUTHERN STATES OF
MEXICO THROUGH FRIDAY EVENING. EARLY ON SATURDAY MORNING THE 
TRAILING END OVER THE GULF RETROGRESS TO THE NORTHERN
GULF/NORTHEAST MEXICO-SOUTH TEXAS. IT IS TO THEN WEAKEN AS IT
MEANDERS NORTH INTO THE SOUTHERN USA LATER IN THE DAY/EARLY SUNDAY
MORNING. FRONTAL CONVECTION OVER THE NORTHWEST BAHAMAS IS TO
SUSTAIN RAINFALL AMOUNTS OF 00-05MM/DAY AND WIDELY ISOLATED MAXIMA
OF 10MM. PREFRONTAL CONVECTION OVER WESTERN CUBA...MEANWHILE...IS
TO SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. ON
THE SOUTHERN STATES OF MEXICO EXPECTING ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15-25MM THROUGH SATURDAY MORNING.

ALSO AT MID LEVELS...A SHORT WAVE TROUGH ON THE SOUTHERN STREAM IS
TO THEN AMPLIFY ACROSS CALIFORNIA TO THE EASTERN PACIFIC LATER ON
SATURDAY. DURING THE DAY ON SUNDAY THE TROUGH REACHES MAXIMUM
AMPLITUDE...DEEPENING ALONG THE COAST OF BAJA PENINSULA. AS IT
DEEPENS...THE TROUGH IS TO ESTABLISH A TROPICAL
CONNECTION...ADVECTING DEEP MOISTURE NORTHWARD ACROSS BAJA
PENINSULA TO SONORA/SINALOA-CHIHUAHUA IN NORTHWEST MEXICO. ACROSS
NORTHERN BAJA PENINSULA THIS IS TO THEN FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-35MM ON SUNDAY TO MONDAY
MORNING...WHILE OVER SONORA-WESTERN CHIHUAHUA-NORTHERN SINALOA IT
IS TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM
DURING THE DAY ON MONDAY.

SOUTH OVER THE CARIBBEAN...A MID/UPPER LEVEL RIDGE DOMINATES FLOW
ACROSS THE BASIN AND CENTRAL AMERICA. A 500 HPA HIGH NORTH OF
PUERTO RICO/VIRGIN ISLES IS TO ANCHOR THIS RIDGE EARLY IN THE
CYCLE. THROUGH SATURDAY MORNING THE HIGH IS FORECAST TO RELOCATE
TO HAITI...WHILE THE RIDGE BUILDS WEST ACROSS NORTHERN CENTRAL
AMERICA TO THE SOUTHERN/CENTRAL STATES OF MEXICO. LATER ON SUNDAY
THE HIGH IS TO ESTABLISH FARTHER TO THE WEST...CENTERING OVER THE
YUCATAN/SOUTHERN STATES OF MEXICO. AS THE RIDGE BUILDS WEST...THIS
IS TO STRENGTHEN THE TRADE WINDS CAP ACROSS THE SOUTHERN STATES OF
MEXICO...WHILE OVER CENTRAL AMERICA-ISLANDS OF THE CARIBBEAN THE
STRONG CAP INVERSION IS TO PERSIST OVER THE NEXT FEW DAYS.

AT LOW LEVELS...AN EAST-TO-WEST RIDGE EXTENDS ACROSS THE ATLANTIC
TO THE NORTHERN CARIBBEAN/GULF OF MEXICO. POLAR FRONT OVER THE
WESTERN ATLANTIC IS TO SLOWLY LIFT OVER THIS AXIS. AS THE TROUGH
PULLS AWAY...THE RIDGE IS TO WEAKEN OVER THE CENTRAL
ATLANTIC...WHILE A SECONDARY CELL IS TO GRADUALLY ESTABLISH ACROSS
THE EASTERN USA-WESTERN ATLANTIC INTO THE GULF LATER DURING THE
WEEKEND. AS THE RIDGE WEAKENS TO THE EAST...GRADIENT OVER THE
TROPICAL ATLANTIC-EASTERN CARIBBEAN IS TO SLACKEN. BUT AS THE
RIDGE STRENGTHENS TO THE WEST...GRADIENT IS TO TIGHTEN ACROSS THE
CENTRAL-WESTERN CARIBBEAN INTO CENTRAL AMERICA AND EASTERN
TROPICAL PACIFIC. EARLY IN THE CYCLE THE TIGHT GRADIENT OVER THE
CENTRAL ATLANTIC-EASTERN CARIBBEAN IS TO SUSTAIN A TRADE WINDS
SURGE ACROSS THE ISLAND CHAIN TO PUERTO RICO-VIRGIN ISLES. THE
STRONG WINDS ARE TO PERSIST THROUGH SUNDAY MORNING...THEN
GRADUALLY WEAKEN THROUGH MONDAY. ACROSS THE CENTRAL-WESTERN
CARIBBEAN WINDS ARE TO SURGE EARLY IN THE CYCLE...AND STRONG WINDS
ARE TO PERSIST ACROSS CENTRAL AMERICA THROUGH MONDAY. THE
STRONGEST ARE EXPECTED ACROSS NICARAGUA...WHERE THE 850 HPA WINDS
ARE TO PEAK AT 40-45KT. IN A STRONG MID LEVEL SUBSIDENCE CAP...THE
STRONG EASTERLY TRADES ARE TO FAVOR ADVECTION OF SHALLOW CLOUD
CLUSTERS ACROSS THE NORTHEAST CARIBBEAN ISLES AND GENERATION OF
STREAMERS ACROSS THE LESSER ANTILLES. ALONG THE ISLAND CHAIN TO
PUERTO RICO AND EASTERN PORTIONS OF HISPANIOLA THIS IS TO THEN
FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. OVER
JAMAICA EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15MM...WITH MOST INTENSE EXPECTED ON SATURDAY. OVER SOUTHEASTERN
NICARAGUA-COSTA RICA EXPECT ACCUMULATION OF 05-10MM/DAY AND MAXIMA
OF 15-20MM ON SATURDAY TO SUNDAY EVENING. BUILDING MID LEVEL RIDGE
IS TO THEN FAVOR RAPID EROSION OF AVAILABLE MOISTURE AS A STRONG
CAP INVERSION ENVELOPS CENTRAL AMERICA.

DOWNSTREAM FROM THE CARIBBEAN RIDGE...AT 250 HPA...A TUTT EXTENDS
TO THE SOUTHWEST ALONG 23N 40W...17N 50W...WINDWARD ISLES TO
NORTHEAST VENEZUELA/SOUTHEAST CARIBBEAN. UNDER INFLUENCE OF THE
RIDGE TO THE WEST... THE TROUGH ALOFT IS TO SHEAR A VORTEX THAT
RETROGRESSES ACROSS VENEZUELA THROUGH MIDDAY ON SATURDAY...INTO
COLOMBIA LATER IN THE DAY/EARLY SUNDAY MORNING. THE TROUGH ALOFT
SUSTAINS AN INDUCED/INVERTED TROUGH IN THE EASTERLY TRADES. THIS
IS TO MOVE IN-TANDEM WITH THE UPPER LEVEL PERTURBATION...BUT TENDS
TO WEAKEN/BECOME ILL DEFINED OVER THE ANDES MOUNTAINS. AS IT PULLS
ACROSS VENEZUELA THIS IS TO INTERACT WITH THE NEAR EQUATORIAL
TROUGH TO THE SOUTH TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-40MM. ACROSS NORTHWEST VENEZUELA TO SANTANDERES IN
COLOMBIA THIS IS TO THEN FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-25MM. FURTHERMORE...A MOIST PLUME ALONG THE NORTHERN
FRINGES OF THIS TROUGH IS TO MIGRATE ALONG THE COAST OF VENEZUELA
TO THE ABC ISLES EARLY IN THE CYCLE...WHERE IT IS TO FAVOR
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM.

A PERTURBATION IN THE EASTERLY TRADES IS TO ENTER FRENCH GUIANA
DURING THE DAY ON MONDAY...WITH MODELS CONSISTENTLY FORECASTING A
RAPID INCREASE IN CONVECTION AS IT MOVES TO SURINAME LATER IN THE
DAY. THIS IS TO FAVOR SCATTERED CONVECTION WITH ACCUMULATION OF
10-15MM/DAY AND MAXIMA OF 20-45MM.

OVER THE EASTERN PACIFIC...THE ITCZ ENTERS THE CONTINENT OVER
SOUTHWEST COLOMBIA...WHERE IT FORECAST TO MEANDER DURING THE NEXT
FEW DAYS. ALSO AT LOW LEVELS...A TROUGH BOUNDS THE COAST OF
COLOMBIA TO ECUADOR. THIS IS ENHANCING COASTAL MOISTURE
CONVERGENCE...WHILE ALSO ADVECTING MOISTURE INTO THE
CENTRAL-SOUTHERN ANDES. IN THIS AREA EXPECTING DIURNAL CONVECTION
TO SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY IN ISOLATED TO
SCATTERED CONVECTION...WITH WIDELY ISOLATED MAXIMA OF 15-20MM/DAY.
AS THE TRADES INTENSIFY ACROSS THE CARIBBEAN-CENTRAL AMERICA...A
GRADUAL DRYING TREND IS THEN EXPECTED LATER DURING THE
WEEKEND...WITH RAINFALL AMOUNTS TO DECREASE TO 00-05MM/DAY AND
WIDELY ISOLATED MAXIMA OF 10MM. HIGHER AMOUNTS... HOWEVER... ARE
TO PERSIST TO THE SOUTHWEST INTO THE CAUCA/CAUCA VALLEY... WITH
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM. THROUGH
SUNDAY MORNING THE MAXIMA IN THIS AREA INCREASES TO 20-40MM.

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)