Prognostic Meteorological Discussion
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FXCA20 KWBC 241822
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TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
221 PM EDT TUE APR 24 2018

TROPICAL DISCUSSION FROM APR 24/12 UTC: CONSISTENT WITH PREVIOUS
FORECASTS...A DEEP  TROUGH MOVES TO THE EASTERN USA LATER
TODAY...TO CONTINUE INTO THE WESTERN ATLANTIC ON WEDNESDAY. THIS
IS TO THEN LIFT OVER A BUILDING RIDGE TO THE SOUTH AND EAST ON
THURSDAY TO FRIDAY. A SECONDARY MID/UPPER LEVEL TROUGH ON THE
SOUTHERN STREAM IS TO FOLLOW...FORECAST TO STREAM ACROSS TEXAS TO
NORTHEAST MEXICO LATER ON WEDNESDAY. THIS IS TO THEN AMPLIFY
ACROSS THE GULF OF MEXICO TO THE YUCATAN/SOUTHERN STATES OF MEXICO
ON THURSDAY...FOCUSING CYCLONIC VORTICITY AND SHORT WAVE ENERGY
ACROSS WESTERN CUBA AND THE NORTHWEST BAHAMAS ON FRIDAY. AT LOW
LEVELS THE ASSOCIATED FRONT MOVES TO SOUTH FLORIDA WHILE TRAILING
ACROSS THE GULF OF MEXICO TO NORTHEAST MEXICO/RIO BRAVO BASIN
LATER TODAY. EARLY ON WEDNESDAY MORNING THE FRONT MEANDERS INTO
THE NORTHWEST BAHAMAS...WITH BOUNDARY TO THEN REMAIN NEARLY
STATIONARY WHILE GRADUALLY WEAKENING LATER ON THURSDAY. AS IT
MEANDERS OVER NORTHEAST STATES OF MEXICO THIS WILL FAVOR SCATTERED
CONVECTION WITH ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-25MM.
AS THE SOUTHERN STREAM TROUGH INTERACTS WITH THIS BOUNDARY ON
WEDNESDAY THIS INCREASES TO 15-20MM/DAY AND MAXIMA OF 30-60MM. ON
THURSDAY THE FOCUS OF THE CONVECTION WILL SHIFT TO VERACRUZ WHERE
IT IS TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-45MM. OVER CHIAPAS-TABASCO-NORTHERN YUCATAN THE UPPER LEVEL
TROUGH IS TO ALSO TRIGGER MODERATE RAINFALL AMOUNTS ON THURSDAY
WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-45MM. ON FRIDAY
EXPECTING SIMILAR AMOUNTS ACROSS QUINTANA ROO AND BELIZE/NORTHERN
GUATEMALA. THIS TROUGH IS TO ALSO ENHANCE DIURNAL CONVECTION ALONG
THE CONTINENTAL DIVIDE OVER SOUTHERN CHIAPAS TO SOUTHERN GUATEMALA
ON THURSDAY...FAVORING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA
OF 20-45MM. ACTIVITY BUILDS ACROSS EL SALVADOR/SOUTHERN HONDURAS
ON THURSDAY-FRIDAY...WITH ACCUMULATION OF 10-15MM/DAY AND MAXIMA
OF 20-30MM. AS THE FRONT MEANDERS OVER THE NORTHWEST
BAHAMAS-WESTERN CUBA...THIS IS TO FAVOR SCATTERED CONVECTION WITH
ACCUMULATION OF 05-10MM/DAY AND MAXIMA OF 15-25MM/DAY. THROUGH
FRIDAY...AS A SUBTROPICAL JET MAXIMA ROUNDS THE BASE OF THE UPPER
LEVEL TROUGH...FAVORING AN UPPER DIVERGENT PATTERN...CONVECTION
ACROSS WESTERN CUBA AND THE NORTHWEST BAHAMAS INCREASES TO
15-20MM/DAY AND MAXIMA OF 35-70MM. NOTE THAT THIS IS TO COINCIDE
WITH FAVORABLE MJO ENVIRONMENTAL CONDITIONS...THUS LEADING TO A
HIGHER RISK OF ORGANIZED DEEP CONVECTION.

FARTHER EAST...A BROAD/LOW AMPLITUDE TROUGH IS TO EXTEND ACROSS
THE CENTRAL ATLANTIC TO THE EASTERN CARIBBEAN/NORTHERN SOUTH
AMERICA LATER TODAY. AS IT PRESSES AGAINST A CELL OF THE
SUBEQUATORIAL RIDGE TO THE EAST...THIS IS TO SUSTAIN A SUBTROPICAL
JET MAXIMA OF 70-90KT ACROSS THE EASTERN CARIBBEAN-FRENCH ISLES
EARLY IN THE CYCLE. THIS JET IS FORECAST TO MEANDER TO THE
EAST-NORTHEAST LATER IN THE WEEK. THE TROUGH IS TO THEN GRADUALLY
PULL WHILE GRADUALLY YIELDING TO A BUILDING RIDGE OVER THE EASTERN
CARIBBEAN. THROUGH THURSDAY THE SHORT WAVE RIDGE IS TO THEN BECOME
THE DOMINANT FEATURE...STRENGTHENING THE TRADE WINDS INVERSION
WHILE CAPPING MOISTURE TO LOWER LEVELS OF THE ATMOSPHERE.
MEANWHILE...ACROSS HISPANIOLA EXPECTING RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-30MM/DAY. OVER PUERTO RICO INITIALLY
EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM...
DECREASING TO 00-05MM/DAY AND MAXIMA OF 10MM ON THURSDAY-FRIDAY.
OVER THE WINDWARD AND FRENCH ISLES THE UPPER LEVEL TROUGH IS TO
INTERACT WITH AN EASTERLY WAVE TO SUSTAIN RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM LATER TODAY...WHILE ON WEDNESDAY
THIS INCREASES TO 05-10MM/DAY AND MAXIMA OF 15MM AS A DEEPER PLUME
OF MOISTURE LIFTS ACROSS THE LESSER ANTILLES TO THE EASTERN
CARIBBEAN.

THE SUBEQUATORIAL RIDGE TO THE SOUTH IS TO EXTEND WEST ACROSS THE
TROPICAL ATLANTIC TO NORTHERN SOUTH AMERICA/SOUTHERN CENTRAL
AMERICA. THIS PATTERN IS TO HOLD DURING THE NEXT FEW DAYS. OVER
THE GUIANAS TO AMAZONIA IN SOUTHERN VENEZUELA THIS IS TO VENT
ITCZ/NEAR EQUATORIAL TROUGH RELATED CONVERGENCE TO FAVOR RAINFALL
AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM. ON WEDNESDAY AND
ONWARD THIS DECREASES TO 10-15MM/DAY AND MAXIMA OF 20-45MM/DAY.
OVER AMAZONIA/EASTERN COLOMBIA EXPECTING ACCUMULATION OF
15-20MM/DAY AND MAXIMA OF 25-50MM/DAY. THROUGH THURSDAY THIS
INCREASES TO 15-20MM/DAY AND MAXIMA OF 30-60MM. ON THE ANDEAN
REGION OF COLOMBIA EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM. ON WEDNESDAY TO THURSDAY THIS INCREASES TO
10-15MM/DAY AND MAXIMA OF 20-35MM/DAY. OVER PANAMA-COSTA
RICA...THE RIDGE ALOFT IS TO VENT ITCZ RELATED CONVECTION...TO
FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM/DAY. ON
WEDNESDAY-THURSDAY THIS IS TO ALSO INCREASE TO 10-15MM/DAY AND
MAXIMA OF 20-35MM/DAY.

TROPICAL/EASTERLY WAVES/TRADE WIND SURGES INITIALIZED AT 12UTC:
INITIAL 24    36    48    60    72    84    96         TYPE    SOF
32W     35W   38W   40W   42W   44W   46W   48W         TW     12N
61W     63W   66W   68W   70W   72W   74W   76W         EW     15N
81W     83W   85W   87W   88W   DISSIPATES              EW     15N

A TROPICAL WAVE ALONG 32W AND SOUTH OF 12N IS TO CONFINE TO THE
ATLANTIC ITCZ DURING THE NEXT FOUR DAYS.

AN EASTERLY WAVE ALONG 61W AND SOUTH OF 15N IS TO ENHANCE NET
RELATED CONVERGENCE ACROSS SOUTHERN VENEZUELA TO FAVOR RAINFALL
AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 25-50MM. OVER THE
FRENCH/WINDWARD ISLES THIS IS TO SUSTAIN RAINFALL AMOUNTS OF
00-05MM/DAY AND MAXIMA OF 10MM EARLY IN THE CYCLE...INCREASING TO
05-10MM/DAY AND MAXIMA OF 15MM ON WEDNESDAY. ON WEDNESDAY-THURSDAY
THIS IS TO THEN TRIGGER SCATTERED CONVECTION ACROSS EASTERN
COLOMBIA TO SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF
20-45MM...INCREASING TO 15-20MM/DAY AND MAXIMA OF 30-60MM ON
THURSDAY. AS IT MOVES INTO WESTERN COLOMBIA ON FRIDAY EXPECTING
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-35MM...WITH MOST
ACTIVE ALONG THE ANDES.

AN EASTERLY WAVE ALONG 81W AND SOUTH OF 15N IS TO ENHANCE ITCZ
RELATED CONVECTION ACROSS PANAMA-COSTA RICA EARLY IN THE
CYCLE...TO FAVOR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15MM. ON WEDNESDAY THIS INCREASES TO 10-15MM/DAY AND MAXIMA OF
20-30MM. AS IT MOVES ACROSS HONDURAS/EL SALVADOR ON WEDNESDAY THIS
IS TO THEN SUSTAIN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF
15-25MM.

HUDSON...MS (JAMAICA)
NIXON...BDM (THE BAHAMAS)
DAVISON...WPC (USA)

$$




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