Prognostic Meteorological Discussion
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FXCA20 KWBC 061858
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
157 PM EST FRI MAR 06 2015

DISCUSSION FROM MARCH 06/00UTC: POLAR TROUGH EXITS THE EASTERN USA
AND ENTERS THE WESTERN ATLANTIC EARLY IN THE CYCLE...WITH AXIS
BOTTOMING OUT TO THE NORTH OF 30N. THE TROUGH IS TO QUICKLY PULL
AWAY...WITH ASSOCIATED SURFACE FRONT LOSING ITS UPPER LEVEL
SUPPORT THROUGH SUNDAY EVENING. AT LOW LEVELS THE FRONT IS TO
MEANDER ACROSS FLORIDA-THE GULF TO THE SOUTHERN STATES OF MEXICO.
AS IT MEANDERS OVER SOUTHERN MEXICO...A WIND SURGE OF 35-40KT IS
TO ACCOMPANY THIS BOUNDARY...ENHANCING MOISTURE CONVERGENCE ACROSS
THE SOUTHERN STATES OF VERACRUZ-CHIAPAS AND TABASCO. THROUGH
SATURDAY EVENING THE FRONT MEANDERS TO THE NORTHWEST
BAHAMAS...WHILE TRAILING ACROSS SOUTHERN FLORIDA-THE GULF TO
SOUTHERN VERACRUZ. DURING THE DAY ON SUNDAY THE FRONT IS TO
RETROGRESS ACROSS FLORIDA TO THE NORTHERN GULF...WHERE IT IS
FORECAST TO FRONTOLIZE. MOST INTENSE CONVECTION IS EXPECTED EARLY
IN THE CYCLE AS THE SURFACE FRONT/STRONG NORTHERLIES CONVERGE ON
THE SOUTHERN STATES OF MEXICO TO SUSTAIN RAINFALL AMOUNTS OF
15-20MM/DAY AND MAXIMA OF 35-70MM. THROUGH SATURDAY THIS DECREASES
TO 05-10MM/DAY AND MAXIMA OF 15MM. SIMILAR AMOUNTS ARE EXPECTED
OVER THE NORTHWEST BAHAMAS THROUGH SUNDAY MORNING. LATER ON
SUNDAY...HOWEVER...AS THE FRONT WEAKENS WHILE MEANDERING NORTH
ACROSS THE GULF...LIGHT RAINFALL IS TO CLUSTER ACROSS
COAHUILA-NORTHERN TAMAULIPAS...WHERE WE EXPECT RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM.

POLAR TROUGH EXITING THE USA IS LIFTING OVER A STRONG MID/UPPER
LEVEL RIDGE THAT EXTENDS ACROSS THE WESTERN ATLANTIC JUST NORTH OF
THE GREATER ANTILLES. AT 500 HPA THE RIDGE BOUNDS BETWEEN
15N-35N...WHILE ANCHORING ON A QUASISTATIONARY HIGH NEAR 24N 62W.
THE RIDGE IS TO DOMINATE THE FLOW ACROSS THE WESTERN
ATLANTIC-NORTHERN CARIBBEAN ISLANDS...MEANWHILE FAVORING A
SUBSIDENCE PATTERN/CAP INVERSION THAT IS FORECAST TO HOLD THROUGH
THE MEDIUM RANGE PERIOD. THIS IS TO TRAP MOISTURE TO LOW LEVELS OF
THE ATMOSPHERE...TO CONFINE TO LEVELS BELOW 750/800 HPA. AT LOW
LEVELS...A BROAD RIDGE EXTENDS FROM THE CENTRAL TO WESTERN
ATLANTIC...WITH POLAR TROUGH OVER THE EASTERN USA SLOWLY LIFTING
OVER THIS AXIS. ALTHOUGH SURFACE FRONT IS TO REMAIN FAR TO THE
NORTH...AS IT RIDES OVER THE RIDGE IT WILL RESULT IN THE RAPID
EROSION OF THIS AXIS LATER THIS EVENING. LATER ON SUNDAY...WITH
THE FRONT WEAKENING TO THE NORTH...THE MODELS FORECAST THE RIDGE
TO SLOWLY STRENGTHEN WHILE BUILDING WEST JUST NORTH OF THE ISLANDS
INTO THE GULF OF MEXICO/ SOUTHERN USA. ALTHOUGH RIDGE
WEAKENS...BRISK EASTERLY TRADES ARE TO PREVAIL ACROSS THE LESSER
ANTILLES/NORTHERN CARIBBEAN ISLANDS. STRONGER WINDS ARE EXPECTED
TO THE SOUTH...ALONG THE COAST OF VENEZUELA-COLOMBIA INTO SOUTHERN
CENTRAL AMERICA/EASTERN TROPICAL PACIFIC. THE BRISK EASTERLY WINDS
WILL SUSTAIN THE GENERATION OF STREAMERS ACROSS THE LESSER
ANTILLES...FORECAST TO AFFECT THE VIRGIN ISLES-PUERTO RICO AND
EASTERN PORTIONS OF HISPANIOLA. RAINFALL AMOUNTS ARE TO RANGE
BETWEEN 00-05MM/DAY WITH ISOLATED MAXIMA OF 10MM.

AT 250 HPA A TUTT BOUNDS THE FRINGES OF THE SUBTROPICAL RIDGE AS
IT EXTENDS TO THE WEST-SOUTHWEST ACROSS THE TROPICAL ATLANTIC TO
THE SOUTHERN CARIBBEAN/NORTHERN COLOMBIA. UPPER TROUGH PATTERN IS
TO GRADUALLY WEAKEN THROUGH MONDAY MORNING...WHEN REMNANTS OF
UPPER TROUGH ARE TO CONFINE TO THE SOUTHEAST CARIBBEAN/NORTHERN
VENEZUELA. AT 500 HPA...THE TROUGH ALOFT IS TO SUSTAIN AN
INDUCED/INVERTED TROUGH OVER THE EASTERN PACIFIC/WESTERN
COLOMBIA...WITH CLOSED LOW TO FORM OFF THE COAST NEAR 03N 85W
LATER ON SATURDAY. AS THE TROUGH DEEPENS THIS IS TO ENHANCE
CONVECTIVE INSTABILITY ALONG THE COASTAL PLAINS OF WESTERN
COLOMBIA AND THE ANDEAN REGION...WHERE WE EXPECT RAINFALL AMOUNTS
OF 05-10MM/DAY AND MAXIMA OF 15-20MM. THIS IS TO PERSIST OVER THE
NEXT FEW DAYS. MOST ACTIVE CONVECTION...HOWEVER...IS EXPECTED TO
THE SOUTH ACROSS AMAZONIA IN SOUTHERN VENEZUELA-COLOMBIA...WITH
MAXIMA IN THIS AREA TO PEAK AT 30-60MM EARLY IN THE CYCLE. THROUGH
SUNDAY EVENING/MONDAY MORNING THIS DECREASES TO MAXIMA OF 15-25MM.

THE TROUGH ALOFT IS TO ALSO ENHANCE SEA BREEZE CONVERGENCE ACROSS
THE GUIANAS...WHERE WE EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15MM. HOWEVER...UNDER INFLUENCE OF TROUGH IN THE
EASTERLY TRADES THAT ENTERS FRENCH GUIANA LATER ON
SATURDAY...CONVECTION ACROSS FRENCH GUIANA-NORTHEAST SURINAME IS
TO INCREASE TO 15-20MM/DAY AND MAXIMA OF 25-50MM. ACROSS BARBADOS
AND THE WINDWARD ISLES THIS IS TO THEN FAVOR RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM.

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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