747
FXCA20 KWBC 181823
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
222 PM EDT THU MAY 18 2023
FORECAST BULLETIN FROM 18 MAY 2023 AT 1800 UTC: A CLOSED UPPER LOW
CENTERS OVER THE CENTRAL BAJA CALIFORNIA PENINSULA. IT IS FORECAST
TO MEANDER SLOWLY NORTHWARD TO CENTER OVER ARIZONA BY SUNDAY.
ALTHOUGH THE UPPER TROUGH IS ADVECTING SOME DRY AIR INTO WESTERN
PORTIONS OF MEXICO...IT IS ALSO PROVIDING SOME VENTILATION TO
ENHANCE DIURNAL CONVECTION IN PORTIONS OF THE EASTERN MEXICAN
PLATEAU ON FRIDAY AND SATURDAY. ON THURSDAY...AREAS OF SCATTERED
AFTERNOON/EVENING CONVECTION ARE EXPECTED ALONG THE NORTHERN
SIERRA MADRE ORIENTAL AND EASTERN EJE VOLCANICO/OAXACA/PUEBLA
WHERE EXPECT 05-10MM/DAY AND MAXIMA OF 15-20MM. ON FRIDAY...EXPECT
05-10MM/DAY AND MAXIMA OF 15-30MM FROM MEXICO/MORELOS NORTH INTO
SAN LUIS POTOSI/SOUTHERN COAHUILA. ON SATURDAY...A SHORT WAVE
UPPER TROUGH IS FORECAST TO ARRIVE FROM THE SOUTHWEST. THIS WILL
INTERACT WITH ENHANCED MOISTURE INFLOW FROM THE GULF OF MEXICO TO
FAVOR STRONG CONVECTION IN NORTHEAST AND PORTIONS OF CENTRAL
MEXICO. EXPECT THE HEAVIEST IN NORTHEAST MEXICO...WHERE AMOUNTS
ARE FORECAST TO REACH 15-20MM/DAY AND MAXIMA OF 35-70MM. FROM
NORTHERN COAHUILA ACROSS EASTERN PORTIONS OF THE MEXICAN PLATEAU
INTO GUANAJUATO/QUERETARO...EXPECT 10-15MM/DAY AND MAXIMA OF
20-45MM.
A SIGNIFICANT DRYING TREND IS UNDERWAY FOR CENTRAL AMERICA. IN THE
MID-LEVELS...A RIDGE IS FORECAST TO RELOCATE FROM CENTRAL
AMERICA/SOUTHERN CARIBBEAN...TO EASTERN MEXICO BY THE WEEKEND. THE
MID-LEVEL RIDGE PATTERN WILL BE PERSISTENT OVER CENTRAL AMERICA
INTO EARLY NEXT WEEK PROVIDING ENHANCED STABILITY. YET...NORTHERLY
FLOW IN THE MID-TROPOSPHERE AND NORTHEASTERLIES IN THE LOWER
TROPOSPHERE ARE EXPECTED TO TRANSPORT A DRY AIR MASS CURRENTLY
ORGANIZING IN THE GULF OF MEXICO AND NORTHWEST CARIBBEAN INTO THE
REGION. THIS WILL SUSTAIN A CONTINUED DECREASE IN THE COVERAGE AND
INTENSITY OF DIURNAL CONVECTION.
A SYSTEM OF INTEREST IS A POLAR TROUGH THAT IS DEEPENING ACROSS
THE PLAINS OF THE USA. THE TROUGH IS FORECAST TO CONTINUE
AMPLIFYING AS IT MOVES INTO FLORIDA/BAHAMAS BY FRIDAY. UNDER THE
INFLUENCE OF A BUILDING UPPER RIDGE OVER THE EASTERN
PACIFIC...MODELS ARE CONFIDENT ON AMPLIFYING THE UPPER TROUGH
FURTHER ON SATURDAY. BY SATURDAY EVENING...EXPECT A TROUGH AXIS
ACROSS THE CENTRAL BAHAMAS...JAMAICA...INTO THE SOUTHWEST
CARIBBEAN NEAR COSTA RICA/PANAMA. SUCH A LARGE AN UNSEASONABLY
STRONG SYSTEM WILL HAVE AN IMPACT IN CONVECTION ACROSS THE
NORTHERN CARIBBEAN AND NORTHERN SOUTH AMERICA. IN THE NORTHERN
CARIBBEAN...A MOIST PLUME CONTINUES PRESENT...WHICH IS HIGHIGHTING
AFTERNOON CONVECTION PRIMARILY IN THE GREATER ANTILLES. THIS WILL
FAVOR 10-15MM/DAY AND MAXIMA OF 20-45MM IN HISPANIOLA AND PUERTO
RICO ON THURSDAY...WHILE IN THE BAHAMAS...CUBA AND JAMAICA EXPECT
05-10MM/DAY AND ISOLATED MAXIMA OF 15-20MM. ON FRIDAY...A SHORT
WAVE TROUGH ARRIVES INTO THE BAHAMAS...TO FAVOR AN INCREASE TO
05-10MM/DAY AND MAXIMA OF 15-30MM FROM THE CENTRAL AND SOUTHEAST
BAHAMAS INTO SOUTHEAST CUBA. IN HISPANIOLA EXPECT MAXIMA OF
25-50MM AND IN PUERTO RICO 20-45MM. ON SATURDAY...THE DEEPENING
UPPER TROUGH WILL INTERACT WITH THE MOIST PLUME IN HISPANIOLA TO
PRODUCE HEAVY RAINFALL. UNDER THE INFLUENCE OF UPPER JET
DYNAMICS...EXPECT AMOUNTS OF 25-50MM/DAY AND MAXIMA OF 75-125MM
WITH A RISK FOR MCS FORMATION. THIS EXTENDS INTO THE MONA PASSAGE
AND NORTHWEST PUERTO RICO. MODERATE CONVECTION IS ALSO EXPECTED IN
THE SOUTHEAST BAHAMAS...TURKS AND CAICOS AND THE HAITIAN
PENINSULA...WHERE EXPECT 10-15MM/DAY AND MAXIMA OF 20-45MM. IN
EASTERN PUERTO RICO EXPECT MAXIMA OF 20-35MM...WHILE IN
JAMAICA...SOUTHEAST CUBA AND THE CENTRAL BAHAMAS EXPECT
05-10MM/DAY AND ISOLATED MAXIMA OF 15-25MM.
IN NORTHERN SOUTH AMERICA...THE MOST ACTIVE CONVECTION IS EXPECTED
IN THE VICINITY OF THE NET...AS WELL AS IN THE PACIFIC BASINS OF
ECUADOR AND COLOMBIA ASSOCIATED WITH PERIODS OF ENHANCED UPPER
FLOW. AN INCREASING TREND IS EXPECTED...ESPECIALLY IN
COLOMBIA...EASTERN PANAMA AND NORTHWEST VENEZUELA...AS THE
AFOREMENTIONED UPPER TROUGH DEEPENS ACROSS THE CARIBBEAN. THIS
WILL SET AN ENVIRONMENT FAVORABLE FOR HEAVY RAINFALL BY SATURDAY
ACROSS THE GULF OF PANAMA/NORTHWEST COLOMBIA...SHIFTING TO
NORTHERN COLOMBIA/NORTHWEST VENEZUELA BY SUNDAY. EXPECT MAXIMA
OVER 100MM IN THUNDERSTORMS DURING THESE PERIODS...AS THE UPPER
TROUGH INTERACTS WITH THE NET AND LOCAL PROCESSES ASSOCIATED WITH
THE TERRAIN OF NORTHERN COLOMBIA AND NORTHWEST VENEZUELA. IN TERMS
OF THE HEAVIEST ACCUMULATIONS...ON THURSDAY EXPECT 20-40MM/DAY AND
MAXIMA OF 50-100MM IN NORTHWEST ECUADOR/SOUTHWEST COLOMBIA...WHILE
IN CENTRAL COLOMBIA EXPECT MAXIMA OF 20-45MM. ON FRIDAY EXPECT
MAXIMXA OF 75-125MM IN SOUTHWEST COLOMBIA AND MAXIMA OF 25-50MM
FROM THE DARIEN/NORTHWEST COLOMBIA INTO THE SANTANDERES. ON
SATURDAY...EXPECT 25-50MM/DAY AND MAXIMA OF 75-125MM FROM CENTRAL
PANAMA INTO NORTHWEST AND NORTHERN COLOMBIA. IN THE SOUTHERN CHOCO
EXPECT 15-30MM/DAY AND MAXIMA OF 40-80MM.
POSITIONS OF TROPICAL/EASTERLY WAVES INITIALIZED AT 12 UTC
TYPE SOF INIT 19/00 19/12 20/00 20/12 21/00 21/12 22/00
EW 12N 60W 62W 63W 64W 67W 69W 71W 73W
TW 16N 75W 77W 79W 80W DISS
EW 20N 86W 89W DISS
AN EASTERLY WAVE IS INITIALIZED AT 60W AND SOUTH OF 12N. BY
THURSDAY...THE WAVE IS FORECAST OVER EASTERN VENEZUELA...WHERE IT
WILL FAVOR MAXIMA OF 20-35MM OVER SOUTHEASTERN VENEZUELA AND
RORAIMA...WHILE IN NORTHEASTERN VENEZUELA EXPECT MAXIMA OF 15MM.
ON FRIDAY...THE WAVE IS EXPECTED OVER EASTERN COLOMBIA/SOUTHERN
VENEZUELA AND WESTERN AMAZONAS-BRASIL...WHERE IT WILL FAVOR
10-15MM/DAY AND MAXIMA OF 20-45MM...WHILE NORTH-CENTRAL VENEZUELA
CAN EXPECT 15-30MM. ON SATURDAY...THE WAVE MOVES WEST OVER WESTERN
VENEZUELA AND EASTERN COLOMBIA...WHERE EXPECT MAXIMA OF 20-45MM.
A TROPICAL WAVE IS INITIALIZED AT 75W AND SOUTH OF 16N. ON
THURSDAY...THE WAVE IS FORECAST ACROSS THE ANDEAN REGION AND
PACIFIC BASINS OF COLOMBIA AND ECUADOR. IN COMBINATION WITH
ENHANCED ONSHORE FLOW...EXPECT MAXIMA INCREASING TO 50-100MM IN
NORTHERN ECUADOR AND SOUTHWEST COLOMBIA...WHILE OTHER AREAS SHOULD
EXPECT 10-15MM/DAY AND MAXIMA OF 20-45MM. ON FRIDAY...THE WAVE IS
EXPECTED TO WEAKEN AS IT PROPAGATES ACROSS PANAMA. IT WILL FAVOR
ISOLATED MAXIMA OF 15MM IN WESTERN PANAMA/EASTERN COSTA RICA.
AN ILL-DEFINED EASTERLY WAVE IS INITIALIZED AT 86W AND SOUTH OF
20N. ON THURSDAY...THE WEAKENING WAVE IS EXPECTED ACROSS EL
SALVADOR/BELIZE/GUATEMALA...WHERE IT WILL FAVOR MAXIMA OF 15-20MM
IN VERY ISOLATED CONVECTION. ON FRIDAY...THE WAVE CONTINUES TO
WEAKEN AND DISSIPATES DUE TO THE INFLUENCE OF AN INTENSIFYING
MID-LEVEL RIDGE ACROSS CENTRAL AMERICA/SOUTHERN MEXICO AS WELL AS
A DRY AIR MASS THAT ENTERS THE REGION FROM THE NORTH.
GALVEZ/ACOSTA...WPC (USA)
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