Prognostic Meteorological Discussion
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FXCA20 KWBC 261923
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
223 PM EST MON JAN 26 2015

DISCUSSION FROM JANUARY 26/00UTC: AMPLIFYING POLAR TROUGH IS TO
DOMINATE MESO-SYNOPTIC FLOW PATTERN OVER THE NEXT FEW DAYS...WITH
MID LEVEL AXIS TO DEEPEN ACROSS THE EASTERN USA TO THE CARIBBEAN
BASIN THROUGH TUESDAY MORNING...WHEN THE TROUGH REACHES MAXIMUM
AMPLITUDE. AS IT AMPLIFIES...THIS IS TO SPLIT THE SUBTROPICAL
RIDGE TO THE SOUTH IN TWO CELLS...WITH THE WESTERNMOST TO CONFINE
TO MEXICO/SOUTHWEST USA...WHILE THE EASTERNMOST DOMINATES FLOW
ACROSS THE CENTRAL/EASTERN ATLANTIC.

DEEP POLAR TROUGH PATTERN ALOFT IS TO PERSIST OVER THE NEXT FEW
DAYS. AT LOW LEVELS...THIS SUSTAINS A BROAD TROUGH ACROSS THE
EASTERN USA/WESTERN ATLANTIC. FLANKING THIS TROUGH...AN ELONGATED
FRONT EXTENDS ACROSS THE CENTRAL BAHAMAS/CUBA TO THE NORTHWEST
CARIBBEAN...WHILE A STRONGER BOUNDARY RACES ACROSS THE FLORIDA
PENINSULA/GULF OF MEXICO. THROUGH TUESDAY MORNING THE LATTER RACES
ACROSS THE BAHAMAS...TO THEN MERGE WITH/REINFORCE THE OLD BOUNDARY
TO THE SOUTH. BY MIDDAY ON TUESDAY THE FRONT IS TO THEN EXTEND
ACROSS THE SOUTHEAST BAHAMAS/TURKS AND CAICOS-EASTERN CUBA TO THE
NORTHWEST CARIBBEAN...AND THROUGH WEDNESDAY MORNING THE TRAILING
END SWINGS SOUTH ACROSS JAMAICA TO NORTHERN HONDURAS.
THIS...HOWEVER...WILL BE A BRIEF INCURSION...WITH TRAILING END TO
THEN RETROGRESS TO THE NORTHWEST CARIBBEAN EARLY ON THURSDAY
MORNING. BOUNDARY IS TO THEN EXTEND ACROSS NORTHERN
HISPANIOLA-CUBA. AS THE FRONT ENTERS THE BAHAMAS-CUBA IT IS TO
TRIGGER RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF
10MM...SIMILARLY ACROSS THE SOUTHEAST BAHAMAS-TURKS-EASTERN CUBA
ON TUESDAY. ACROSS NORTHERN HISPANIOLA IT IS TO THEN FAVOR
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM LATER ON
THURSDAY. FRONTAL NORTHERLIES OF 15-20KT OVER THE WESTERN
CARIBBEAN ARE TO THEN FAVOR SCATTERED CONVECTION ALONG THE NORTH
COAST OF HONDURAS/ISLAS DE LA BAHIA TO NORTHEAST GUATEMALA...WITH
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-30MM. THROUGH
WEDNESDAY MORNING THIS DECREASES TO 05-10MM/DAY AND MAXIMA OF 15MM.

AS THE FRONT ACCELERATES ACROSS THE NORTHERN CARIBBEAN ISLES...IT
IS TO TRIGGER A PREFRONTAL SHEAR LINE AND AN INDUCED/INVERTED
TROUGH OVER THE CARIBBEAN. THE SHEAR LINE IS TO EXTEND ACROSS
JAMAICA TO COSTA RICA/EASTERN NICARAGUA LATER THIS EVENING. EARLY
ON TUESDAY IT MOVES TO HAITI...TRAILING ACROSS THE SOUTHERN
CARIBBEAN TO PANAMA AS THE TRADE WINDS OVER THE CENTRAL/WESTERN
CARIBBEAN INCREASE TO 20-30KT. STRONGER WINDS ARE EXPECTED ACROSS
NICARAGUA TO THE EASTERN TROPICAL PACIFIC. THROUGH WEDNESDAY
MORNING THE SHEAR LINE MOVES TO THE DOMINICAN REPUBLIC...TRAILING
TO PANAMA/SOUTHERN CARIBBEAN AS STRONG NORTHERLY TRADES PERSIST.
THROUGH THURSDAY MORNING THE SHEAR LINE MOVES TO PUERTO
RICO...TRAILING TO THE SOUTHERN CARIBBEAN/ SOUTHERN CENTRAL
AMERICA. THE INDUCED/INVERTED TROUGH...MEANWHILE...IS TO GRADUALLY
RELOCATE TO THE EASTERN CARIBBEAN LATER IN THE WEEK. VEERING WINDS
ARE TO THEN ENHANCE MOISTURE TRANSPORT ACROSS THE ISLAND CHAIN TO
THE NORTHERN CARIBBEAN ISLES. AS THE SHEAR LINE MEANDERS ACROSS
EASTERN CUBA-JAMAICA-HAITI IT IS TO FAVOR SCATTERED CONVECTION
WITH ACCUMULATION OF 00-05MM/DAY AND MAXIMA OF 10MM. ACROSS
NORTHERN HISPANIOLA...INITIALLY EXPECTING ACCUMULATION OF
10-15MM/DAY AND MAXIMA OF 20-30MM. THROUGH THURSDAY MORNING MAXIMA
IS TO INCREASE TO 20-45MM...WHILE BUILDING EAST ACROSS PUERTO RICO
LATER ON THURSDAY. OVER SOUTHERN CENTRAL AMERICA SHEAR LINE
CONVERGENCE WILL FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA
OF 15-20MM THROUGH ON TUESDAY...INCREASING TO 10-15MM/DAY AND
MAXIMA OF 20-45MM ON WEDNESDAY.

AS THE LOW LEVEL TRADES SURGE ACROSS THE CARIBBEAN/CENTRAL
AMERICA...THE EASTERN PACIFIC ITCZ IS TO THEN QUICKLY MOVE SOUTH
TO ITS CLIMATOLOGICAL POSITION NEAR THE EQUATOR LATER ON
WEDNESDAY. STRONG NORTHERLIES ACROSS PANAMA/COSTA RICA ARE TO THEN
FAVOR UPWELLING OF COLD WATER ALONG THE COAST OF
COLOMBIA/PANAMA...LEADING TO A GRADUAL DECREASE IN COASTAL
CONVECTION ON THE ANDEAN REGION AND WEST COAST OF COLOMBIA. EARLY
IN THE CYCLE EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA
OF 15-20MM. THIS DECREASES TO 00-05MM/DAY AND MAXIMA OF 10MM. AN
INCREASE...HOWEVER...IS EXPECTED OVER SOUTHWEST
COLOMBIA/ECUADOR...WHERE THE ITCZ IS TO FAVOR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-35MM.

CELL OF THE SUBTROPICAL RIDGE TO THE WEST IS THEN FORECAST TO
GRADUALLY BUILD ACROSS MEXICO TO THE WESTERN USA...AS IT IS TO
ANCHOR ON A 500 HPA HIGH NEAR COLIMA/NAYARIT IN SOUTHWEST MEXICO.
THROUGH WEDNESDAY EVENING THE RIDGE IS TO THEN ENVELOP MOST OF
MEXICO-THE GULF AND NORTHERN PORTIONS OF CENTRAL AMERICA. EARLY IN
THE CYCLE...THE RIDGE AND A TROUGH TO THE NORTHWEST ARE TO SUSTAIN
A MOIST ADVECTIVE PATTERN ACROSS THE SIERRA MADRE
OCCIDENTAL/NORTHWEST STATES OF MEXICO. BUT AS THE RIDGE BUILDS AND
THE SUBSIDENCE CAP STRENGTHENS...THIS IS TO RAPIDLY WEAKEN THROUGH
MIDDAY ON TUESDAY. MEANWHILE...EXPECTING RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM.

ALSO AT MID LEVELS...A WEAKER CELL OF THE RIDGE IS TO MEANDER OVER
THE CENTRAL ATLANTIC EARLY IN THE CYCLE...TO RELOCATE TO THE
WESTERN ATLANTIC LATER ON WEDNESDAY. AS THE RIDGE PATTERN
EVOLVES...A TUTT/TUTT LOW TO THE EAST IS TO RELOCATE ALONG THE
EASTERN/SOUTHERN FRINGES OF THIS RIDGE. THROUGH WEDNESDAY EVENING
THE LOW IS EXPECTED TO MOVE TO THE CENTRAL TROPICAL ATLANTIC WHILE
THE TROUGH AMPLIFIES TO THE NORTHERN GUIANAS. THIS IS TO THEN
PROVIDE VENTILATION ALOFT TO CONVECTION ACROSS SURINAME AND FRENCH
GUIANA WHERE WE EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA
OF 15MM...FORECAST TO INCREASE TO 15-20MM LATER ON THURSDAY.

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

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





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