958
FXCA20 KWBC 201730
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1230 PM EST MON NOV 20 2023
FORECAST BULLETIN 20 NOV 2023 AT 1730 UTC: A PROGRESSIVE TRAIN OF
UPPER TROUGHS AND RIDGES ARE PROPAGATING IN THE WESTERLIES ACROSS
THE USA. A POTENT POLAR TROUGH EXTENDS THAT EXTENDS ACROSS THE
PLAINS OF THE USA/US SOUTHWEST ON MONDAY...IS FORECAST TO MEANDER
EASTWARD...ENTERING THE ATLANTIC EARLY ON THURSDAY. AS IT
PROPAGATES...THE BUILDING POLAR HIGH WILL PUSH A SURFACE FRONT
SOUTHWARD. BY MONDAY EVENING THE FRONT IS EXPECTED ACROSS CENTRAL
LOUISIANA...NORTHERN NUEVO LEON...CENTRAL DURANGO...SIERRA
TARAHUMARA. BY TUESDAY EVENING EXPECT IT ACROSS THE FLORIDA
PANHANDLE...23N 93W...TABASCO...CHIVELA PASS...CENTRAL MEXICAN
PLATEAU...SIERRA MADRE OCCIDENTAL. BY WEDNESDAY EVENING EXPECT THE
BOUNDARY ACROSS CENTRAL FLORIDA...NORTH-CENTRAL YUCATAN
PENINSULA...PETEN IN GUATEMALA...CENTRAL GUATEMALA...CHIVELA PASS
INTO THE CENTRAL MEXICAN PLATEAU AND SIERRA MADRE OCCIDENTAL. A
TEHUANTEPECER LOW-LEVEL JET IS EXPECTED TO DEVELOP LATE ON TUESDAY
EVENING...AND IS FORECAST TO LAST THROUGH MIDDAY THURSDAY. NOTE
THAT THIS FRONT WILL MAKE IT INTO WESTERN PORTIONS OF
MEXICO...COVERING MOST OF CENTRAL AND NORTHERN MEXICO UNDER THE
FRONTAL AIR MASS. DUE TO THE FRONTAL INVERSION AND ASCENT INDUCED
BY AN APPROACHING UPPER TROUGH...EXPECT PLENTY OF CLOUD COVER AND
SCATTERED PRECIPITATION DEVELOPING ON TUESDAY AND LINGERING
THROUGH THURSDAY IN THE ENTIRE MEXICAN PLATEAU AND GULF COAST OF
MEXICO. IN TERMS OF PRECIPITATION...THE FRONT WILL ONLY ENCOUNTER
SUFFICIENT MOISTURE TO FAVOR AN INCREASE IN PRECIPITATION ON
TUESDAY. FROM TUESDAY MORNING THROUGH WEDNESDAY MORNING EXPECT
10-15MM/DAY AND MAXIMA OF 20-35MM DEVELOPING FROM
MICHOACAN/GUERRERO INTO TABASCO AND CHIAPAS IN SOUTHERN MEXICO. IN
THE CENTRAL MEXICAN PLATEAU AND SIERRA MADRE
ORIENTAL...ENHANCEMENT BY THE UPPER TROUGH WILL FAVOR 05-10MM/DAY
AND MAXIMA OF 15MM. ON WEDNESDAY...ENHANCED OROGRAPHIC UPLIFT WILL
FAVOR 15-20MM/DAY AND MAXIMA OF 25-50MM IN TABASCO/CHIAPAS. IN
SOUTHWEST MEXICO EXPECT 10-15MM/DAY AND MAXIMA OF 20-35MM AS A
SECONDARY UPPER TROUGH ESTABLISHES ITS DIVERGENT TIER OVER THE
REGION INTERACTING WITH THE MOIST PLUME. IN THE CENTRAL AND
NORTHERN MEXICAN PLATEAU...INCLUDING PORTIONS OF NAYARIT/JALISCO
AND NORTHEAST MEXICO...EXPECT 05-10MM/DAY AND SCATTERED MAXIMA OF
15-25MM. ALSO ON WEDNESDAY...EXPECT 05-10MM/DAY AND MAXIMA OF 15MM
DEVELOPING FROM THE SOUTHERN YUCATAN PENINSULA INTO CENTRAL
GUATEMALA/SOUTH BELIZE AND NORTHERN HONDURAS IN ASSOCIATION WITH
UPSLOPE AND ONSHORE FLOW.
ANOTHER FRONT HAS ORGANIZED TO THE EAST. BY MONDAY EVENING EXPECT
IT JUST TO THE SOUTH OF THE TURKS AND CAICOS...SIERRA MAESTRA IN
FAR SOUTHEAST CUBA...JUST NORTH OF THE CAYMAN ISLANDS. BY TUESDAY
EVENING EXPECT THE FRONT ALONG 21N 60W...ST. CROIX...JUST SOUTH OF
PUERTO RICO AND HISPANIOLA ALONG 17N...FAR EASTERN JAMAICA. BY
WEDNESDAY EVENING EXPECT THE BOUNDARY ALONG 18N 57W...LEEWARD
ISLANDS...INTO A WEAKENING BOUNDARY ALONG 16N INTO 16N 72W. THIS
FRONT IS INTERACTING WITH THE MOIST PLUME THAT PRODUCED HEAVY
RAINFALL IN HISPANIOLA DURING THE WEEKEND. THE MOIST PLUME
ASSOCIATES WITH A SURFACE TROUGH THAT IS FORECAST ALONG 24N
64W...WEST PUERTO RICO...TO A LOW NEAR 14N 73W ON MONDAY EVENING.
IN TERMS OF PRECIPITATION...EXPECT STILL MODERATE TO LOCALLY HEAVY
AMOUNTS IN ASSOCIATION WITH THE MOIST PLUME AND THE SURFACE TROUGH
OF LOW PRESSURE AS IT PROPAGATES ACROSS EASTERN HISPANIOLA AND
PUERTO RICO. THROUGH EARLY TUESDAY THIS WILL FAVOR 10-15MM/DAY AND
MAXIMA OF 20-45MM ALTHOUGH ISOLATED HIGHER AMOUNTS ARE POSSIBLE
GIVEN HIGH VALUES OF AVAILABLE MOISTURE. WITH THE FRONT...EXPECT
MAXIMA GENERALLY UNDER 10MM/DAY IN THE BAHAMAS AND NORTHEAST COAST
OF CUBA DUE TO LIGHT COLD AIR CUMULUS PRECIPITATION IN ASSOCIATION
WITH THE COLD ADVECTIVE PATTERN ESTABLISHED BEHIND THE BOUNDARY.
BY TUESDAY...EXPECT THE LARGEST ACCUMULATIONS IN THE LEEWARD
ISLANDS AND ST. CROIX WHERE EXPECT 05-10MM/DAY AND MAXIMA OF
15-25MM. IN PUERTO RICO/VI EXPECT MAXIMA OF 15MM. SIMILAR AMOUNTS
ARE EXPECTED IN NORTHERN HISPANIOLA AND FAR EASTERN CUBA DUE TO
COLD AIR CUMULUS MOVING IN FROM THE EAST-NORTHEAST. IN THE REST OF
THE NORTHEAST COAST OF CUBA EXPECT MAXIMA UNDER 10MM/DAY. ON
WEDNESDAY...EXPECT 05-10MM/DAY AND ISOLATED MAXIMA OF 15MM IN THE
LEEWARD ISLANDS. COLD AIR CUMULUS CONVECTION WILL FAVOR MAXIMA
UNDER 10MM/DAY AND THE NORTHEAST COAST OF CUBA...WHILE MORE
ISOLATED PRECIPITATION IS EXPECTED IN HISPANIOLA AND PUERTO RICO
AS A DRIER AIR MASS ENTERS THE REGION.
IN SOUTHERN CENTRAL AMERICA AND NORTHERN SOUTH AMERICA...EXPECT
MUCH MORE CONSERVATIVE RAINFALL AMOUNTS THAN DURING THE LAST
SEVERAL DAYS AS THE UPPER SYNOPTIC PATTERN BECOMES LESS DIVERGENT
IN ASSOCIATION WITH THE MJO. STILL...ITCZ CONVERGENCE WILL
MAINTAIN ACTIVE CONVECTION FROM SOUTHEAST NICARAGUA ACROSS MOST OF
COSTA RICA AND WEST PANAMA THROUGH THE CYCLE. EXPECT AMOUNTS OF
05-10MM/DAY AND ISOLATED MAXIMA OF 15-30MM ON A DAILY BASIS. IN
COLOMBIA...EXPECT MAXIMA GENERALLY IN THE 15-35MM/DAY
RANGE...ALTHOUGH HIGHER AMOUNTS ARE POSSIBLE IN SOUTHWEST COLOMBIA
DUE TO ENHANCED ONSHORE FLOW.
LONGITUDE POSITIONS OF TROPICAL/EASTERLY WAVES INITIALIZED AT 12
UTC
TYPE SOF INIT 21/00 21/12 22/00 22/12 23/00 23/12 24/00 24/12
EW 12N 47W 49W 51W 53W 55W 57W 59W 61W 63W
AN EASTERLY WAVE IS INITIALIZED AT 47W AND SOUTH OF 12N. ALTHOUGH
ONLY SHALLOW CONVECTION IS ASSOCIATED WITH THIS SYSTEM...THE WAVE
IS FORECAST TO HIGHLIGHT DIURNAL CONVECTION AS IT PROPAGATES
ACROSS FRENCH GUIANA/EASTERN SURINAME ON TUESDAY WHERE IT WILL
FAVOR 05-10MM/DAY AND ISOLATED MAXIMA OF 15-25MM. ON WEDNESDAY IT
WILL FAVOR 05-10MM/DAY AND MAXIMA OF 15-20MM IN SURINAME AND
GUYANA.
GALVEZ...WPC (USA)
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