Prognostic Meteorological Discussion
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FXCA20 KWBC 201925
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
224 PM EST MON NOV 20 2017

TROPICAL DISCUSSION FROM NOV 20/12 UTC: A MID/UPPER LEVEL RIDGE
OVER NORTHWESTERN MEXICO/SOUTHWEST USA IS STEERING A SHORT WAVE
TROUGH ACROSS TEXAS TO THE WESTERN GULF. AS IT CLEARS THE FRINGES
OF THE MID LEVEL RIDGE THE TROUGH IS TO THEN DEEPEN ACROSS THE
GULF TO THE CAMPECHE SOUND LATER THIS AFTERNOON. THIS SETS THE
STAGE FOR A SECONDARY PERTURBATION TO FOLLOW...WITH MID LEVEL
VORTEX MOVING ACROSS TEXAS TO THE NORTHWEST GULF EARLY ON
WEDNESDAY MORNING. THIS IS TO THEN DEEPEN OVER THE GULF OF MEXICO
TO THE YUCATAN PENINSULA/CENTRAL GUATEMALA-BELIZE ON WEDNESDAY
EVENING. AT LOW LEVELS AN ELONGATED FRONT STRETCHES ACROSS THE
NORTHWEST BAHAMAS-SOUTHERN FLORIDA TO THE NORTHEAST STATES OF
MEXICO. LATER TODAY/EARLY ON TUESDAY MORNING THE FRONT IS TO
RETROGRESS ACROSS CENTRAL FLORIDA TO THE NORTHERN GULF. ON
WEDNESDAY...AS THE MID LEVEL TROUGH DEEPENS ACROSS THE GULF...IT
IS TO INDUCE A FRONTAL LOW ALONG THE MEANDERING BOUNDARY OVER THE
GULF. THE LOW IS TO GRADUALLY DEEPEN AS IT LIFTS ACROSS FLORIDA
LATER IN THE WEEK. THIS WILL TIGHTEN THE GRADIENT AND IT IS TO
SUSTAIN A NORTHERLY LOW LEVEL FLOW OF 25-30KT ACROSS THE WESTERN
GULF ON WEDNESDAY THAT DISPLACES THE FRONT SOUTH TO TAMAULIPAS IN
NORTHEAST MEXICO LATER IN THE DAY. ON THURSDAY MORNING THE FRONT
SURGES ACROSS VERACRUZ-OAXACA...AND ON THURSDAY EVENING IT REACHES
THE NORTHERN YUCATAN PENINSULA/SOUTHERN STATES OF MEXICO. AS IT
SURGES ACROSS THE GULF OF MEXICO THIS IS TO INITIALLY FAVOR LIGHT
CONVECTION BETWEEN SOUTHERN TAMAULIPAS-NORTHERN VERACRUZ...WITH
ACCUMULATION OF 00-05MM/DAY AND MAXIMA OF 10MM. ON
WEDNESDAY-THURSDAY...BRISK FRONTAL NORTHERLIES OVER THE CAMPECHE
SOUND ARE TO ENHANCE LOW LEVEL MOISTURE CONVERGENCE ACROSS
SOUTHERN VERACRUZ-NORTHERN CHIAPAS...WHERE WE EXPECT RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM...WHILE OVER
CAMPECHE/YUCATAN EXPECTING RAINFALL AMOUNTS OF 00-05MM/DAY AND
MAXIMA OF 10MM.

AS THE POLAR TROUGH DEEPENS TO THE WEST...A MID LEVEL CELL OF THE
SUBEQUATORIAL RIDGE IS TO THEN AMPLIFY ACROSS THE ISLAND CHAIN TO
THE EASTERN CARIBBEAN LATER THIS EVENING. AS THE PATTERN
EVOLVES...SHORT WAVE TROUGH OVER THE WESTERN CARIBBEAN IS TO
FINALLY FILL WHILE SHEARING SHORT WAVE ENERGY ACROSS
HISPANIOLA-WESTERN PUERTO RICO EARLY IN THE PERIOD. ON
WEDNESDAY-THURSDAY THE MID LEVEL RIDGE IS TO THEN CENTER ON A
CLOSED HIGH OVER PUERTO RICO. THE BUILDING MID LEVEL RIDGE IS TO
SUSTAIN A STRONG TRADE WINDS CAP ACROSS THE EASTERN CARIBBEAN
ISLES LATER THIS EVENING. THIS EXPANDS ACROSS THE VIRGIN ISLES TO
PUERTO RICO LATER THIS EVENING...TO REMAIN STRONG AND WELL
ENTRENCHED THROUGH AT LEAST THURSDAY MORNING. THIS WILL BE
ACCOMPANIED BY A SHARP DROP IN AVAILABLE WATER ACROSS PUERTO
RICO-VIRGIN ISLES LATER TODAY. MEANWHILE...ACROSS PUERTO RICO
EXPECTING RAINFALL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF
25-50MM...WHILE ACROSS THE VIRGIN ISLES EXPECTING RAINFALL AMOUNTS
OF 00-05MM/DAY AND MAXIMA OF 10MM. FAIR WEATHER CONDITIONS WILL
THEN PREVAIL THROUGH THURSDAY MORNING.

AT LOW LEVELS...AN ILL ORGANIZED LOW SOUTH-SOUTHWEST OF HAITI
EXTENDS A SHORT WAVE TROUGH TO NORTHERN COLOMBIA. THE LOW/TROUGH
IS ENHANCING LOW LEVEL MOISTURE CONVERGENCE ACROSS THE CENTRAL
CARIBBEAN...WITH PLUME OF TROPICAL MOISTURE LIFTING ALONG THE
WESTERN FRINGES OF THE SUBEQUATORIAL RIDGE TO PUERTO RICO AND THE
DOMINICAN REPUBLIC. AS PREVIOUSLY INDICATED BUILDING MID LEVEL
RIDGE IS TO SUSTAIN RAPID EROSION OF AVAILABLE WATER ACROSS PUERTO
RICO LATER THIS EVENING...AND ACROSS HISPANIOLA LATER IN THE
MORNING ON TUESDAY. OVER SOUTHERN HISPANIOLA EXPECTING RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM THROUGH THIS
EVENING...WHILE ACROSS NORTHERN HALF OF THE ISLAND EXPECT
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-20MM. ON
TUESDAY...LIGHT TO MODERATE CONVECTION ACROSS THE HAITIAN
PENINSULA WILL RESULT IN ADDITIONAL RAINFALL AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM.

BUILDING RIDGE OVER THE WESTERN NORTH ATLANTIC ON
MONDAY-TO-TUESDAY IS TO THEN FAVOR A BRISK EASTERLY FLOW ACROSS
THE ISLAND CHAIN-EASTERN/CENTRAL CARIBBEAN. THE SURFACE LOW SOUTH
OF HAITI WILL WEAKEN TO AN OPEN TROUGH THAT RELOCATES ACROSS
JAMAICA DURING EARLY MORNING HOURS ON TUESDAY...NEARING 80W LATER
IN THE DAY...WHERE IT IS TO THEN REMAIN THROUGH THURSDAY MORNING.
AS IT MEANDERS ACROSS JAMAICA/EASTERN CUBA-THE TURKS AND CAICOS
THIS WILL FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-35MM...WITH MAXIMA OF 20-40MM ACROSS EASTERN CUBA/JAMAICA ON
WEDNESDAY.

AS THE LOW LEVEL TROUGH RELOCATES ACROSS THE CENTRAL CARIBBEAN IT
IS TO ALSO FAVOR AN INCREASE IN DIURNAL CONVECTION OVER SOUTHERN
CENTRAL AMERICA. ACROSS COSTA RICA/SOUTHERN NICARAGUA-PANAMA
INITIALLY EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-20MM. THROUGH WEDNESDAY THIS INCREASES TO 10-15MM/DAY AND
MAXIMA OF 20-30MM. OVER WESTERN COLOMBIA/ANDEAN REGION EXPECTING
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM. ON
WEDNESDAY...AS A WESTERLY FLOW ESTABLISHES OVER THE EASTERN
PACIFIC...THIS WILL ENHANCE COASTAL CONVERGENCE TO FAVOR RAINFALL
AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 30-60MM. ACROSS VENEZUELA
EXPECT RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-20MM...WITH MOST INTENSE OVER AMAZONIA TO THE SOUTH.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:
INITIAL   24    36    48    60    72    84    96    TYPE
SOF
42W      44W   46W   49W   52W   54W   57W   60W    EW
16N
47W      48W   50W   52W   54W   56W   58W   60W    TUTT-INDCD
28N
55W      58W   60W   63W   65W   67W   69W   71W    EW
12N
73W      74W   75W   77W   78W   DISSIPATES         EW
18N

AN EASTERLY WAVE IS INITIALIZED ALONG 42W. THE ECMWF IS DOING
SLIGHTLY BETTER THAN THE GFS WITH THE FORECAST OF THIS FEATURE.
EXPECTING THE WAVE TO REACH FRENCH GUIANA EARLY ON WEDNESDAY
MORNING...TO FAVOR LIGHT RAINFALL AMOUNTS IN ISOLATED CONVECTION.
THIS QUICKLY SPREADS ACROSS SURINAME DURING THE MORNING. ACROSS
GUYANA/NORTHEAST VENEZUELA AND TRINIDAD/TOBAGO THIS IS TO THEN
SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM.

TUTT INDUCED PERTURBATION IN THE EASTERLY TRADES EXTENDS ALONG 42W
AND NORTH OF 20N. THIS REACHES THE NORTHEAST CARIBBEAN LATER ON
THURSDAY. THIS...HOWEVER...IS GOING TO HAVE A HARD TIME OVERCOMING
NEGATIVE INFLUENCE OF MID LEVEL RIDGE OVER THE NORTHEAST
CARIBBEAN. AS A RESULT...ONLY EXPECTING LIGHT ISOLATED CONVECTION
IN ASSOCIATION WITH THIS FEATURE.

AN EASTERLY WAVE ALONG 55W AND SOUTH OF 12N MOVE TO
GUYANA/SOUTHERN WINDWARD ISLES-NORTHEAST VENEZUELA LATER THIS
EVENING...TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-20MM. EARLY ON TUESDAY THIS INCREASES TO 10-15MM/DAY AND MAXIMA
OF 20-35MM. ACROSS VENEZUELA THIS IS TO THEN FAVOR RAINFALL
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM ACROSS AMAZONIA TO
THE SOUTH.

AN ILL ORGANIZED EASTERLY WAVE ALONG 73W IS PHASING WITH
MEANDERING TROUGH OVER THE CENTRAL CARIBBEAN. MOST ACTIVE
CONVECTION WITH THIS FEATURE IS EXPECTED OVER WATER ACROSS THE
CENTRAL CARIBBEAN. EARLY ON TUESDAY MORNING IT IS TO ENHANCE
CONVECTION ACROSS JAMAICA-EASTERN CUBA TO FAVOR RAINFALL AMOUNTS
OF 10-15MM/DAY AND MAXIMA OF 20-35MM...WHILE OVER NORTHERN
COLOMBIA EXPECTING ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF
15-20MM.

GUY...NMS (BELIZE)
PECK...MS (JAMAICA)
RIVAS...SENAMHI (PERU)
DAVISON...WPC (USA)

$$





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