128
FXCA20 KWBC 161918
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
218 PM EST FRI DEC 16 2022
NOTE: IN THE MEDIUM RANGE...MODELS HAVE BEEN PERSISTENT IN
RESOLVING A POTENT EXTRATROPICAL CYCLONE AND ASSOCIATED COLD AIR
INTRUSION AFFECTING MOST OF THE CENTRAL AND EASTERN UNITED STATES
FROM DECEMBER 22 THROUGH DECEMBER 26. THE ASSOCIATED POLAR HIGH
WILL BE STRONG ENOUGH TO FAVOR THE DEVELOPMENT OF A STRONG COLD
FRONT OF RAPID PROPAGATION...FORECAST TO REACH THE SOUTHEAST
BAHAMAS...SOUTHEAST CUBA/CAYMAN ISLANDS AND EASTERN
HONDURAS/EASTERN NICARAGUA BY DECEMBER 24TH. THIS INCLUDES THE
POTENTIAL FOR STRONG GAP WINDS IN THE TEHUANTEPEC AND
NICARAGUA/PAPAGAYO GAP...AS WELL AS A SHEAR LINE EXTENDING INTO
EASTERN COSTA RICA. NOTEWORTHY ARE UNUSUALLY LOW TEMPERATURES
DEVELOPING AS FAR SOUTH AS THE YUCATAN
PENINSULA...GUATEMALA...HONDURAS AND EL SALVADOR. DETAILS ON THIS
EVOLUTION SHOULD BECOME MORE CLEAR IN THE NEXT FEW DAYS.
FORECAST BULLETIN FROM 16 DEC 2022 AT 18 UTC: IN THE UPPER
LEVELS...A BROAD RIDGE EXTENDS FROM A HIGH OVER WESTERN VENEZUELA
AND COVERS ALL OF CENTRAL AMERICA...GULF OF MEXICO...AND
CENTRAL/WESTERN PORTIONS OF THE CARIBBEAN. THIS...IN COMBINATION
WITH A MID-LEVEL RIDGE OVER THE NORTHWEST CARIBBEAN/SOUTHEAST GULF
OF MEXICO...WILL BLOCK THE SOUTHWARD UNDULATION OF POLAR TROUGHS
PROPAGATING IN THE WESTERLIES DURING THE WEEKEND AND INTO EARLY
NEXT WEEK. AS A RESULT...THE CURRENT FRONT IN NORTHERN PORTIONS OF
THE BASIN IS FORECAST TO REMAIN GENERALLY NORTH OF 20N THROUGH THE
WEEKEND. ON FRIDAY EVENING...THE FRONT IS EXPECTED ALONG 30N
70W...NORTHWEST BAHAMAS...SOUTH FLORIDA...SOUTHERN TAMAULIPAS. ON
SATURDAY EVENING...IT IS EXPECTED ALONG 30N 60W...EXTREME
NORTHWEST BAHAMAS...SOUTH FLORIDA...NORTHERN VERACRUZ...AND ALONG
THE SIERRA MADRE ORIENTAL INTO WESTERN COAHUILA. ON SUNDAY EVENING
IT IS EXPECTED ALONG 30N 65W...CENTRAL BAHAMAS...WESTERN
CUBA...OFF THE COAST OF THE NORTHERN YUCATAN
PENINSULA...RETREATING INTO NORTHERN TAMAULIPAS. AS THE FRONT
MEANDERS SOUTHWARD ON SUNDAY...EXPECT THE DEVELOPMENT OF A SHEAR
LINE...FORECAST TO EXTEND ACROSS THE SOUTHEAST BAHAMAS...EXTREME
SOUTHEAST CUBA...EXTREME NORTHWEST JAMAICA...NORTHEAST HONDURAS BY
SUNDAY EVENING. IN TERMS OF RAINFALL...IN THE NORTHWEST
BAHAMAS...EXPECT 05-10MM/DAY AND MAXIMA OF 15MM ON FRIDAY AND
SATURDAY. YET...UPPER TROUGH DYNAMICS AND ENHANCED INSTABILITY
WILL FAVOR 05-10MM/DAY AND ISOLATED MAXIMA OF 15-25MM WITH
THUNDERSTORMS ON SUNDAY. IN WESTERN CUBA...EXPECT 05-10MM/DAY AND
MAXIMA OF 15MM ON SUNDAY. IN TAMAULIPAS...EXPECT 00-05MM/DAY AND
MAXIMA OF 10MM ON FRIDAY...INCREASING TO MAXIMA OF 15MM ON
SATURDAY AND DECREASING TO MAXIMA OF 10MM ON SUNDAY AGAIN. IN
TERMS OF THE SHEAR LINE ON SUNDAY...EXPECT LITTLE PRECIPITATION
GIVEN THE LACK OF SIGNIFICANT AMOUNTS OF AVAILABLE MOISTURE.
ANOTHER SHEAR LINE IS FORECAST TO CONTINUE MEANDERING FROM THE
TROPICAL NORTH ATLANTIC INTO THE ARC OF THE LESSER ANTILLES
THROUGH THE FORECAST CYCLE. GIVEN THE INFLUENCE OF THE MID-LEVLE
RIDGE AND LIMITED AMOUNTS OF AVAILABLE MOISTURE...EXPECT
ACCUMULATIONS TO LIMIT TO 05-10MM/DAY AND MAXIMA OF 15MM WITH THIS
SYSTEM. THIS WILL AFFECT AREAS BETWEEN MARTINIQUE AND GUADELOUPE
ON FRIDAY...BETWEEN DOMINICA AND GUADELOUPE ON SATURDAY...AND ON
SUNDAY THIS WILL CLUSTER IN THE SOUTHERN LEEWARD ISLANDS.
THE CARIBBEAN LOW-LEVEL JET IS FORECAST TO REMAIN STRONG THROUGH
THE CYCLE...WHICH WILL FAVOR SEASONAL CONVECTION ALONG THE
CARIBBEAN COAST OF CENTRAL AMERICA ON A DAILY BASIS. GIVEN SUBTLE
VARIABILITIES IN LOW-LEVEL MOISTURE...EXPECT THE HEAVIEST
PRECIPITATION ON SATURDAY FOLLOWED BY A DECREASE IN AMOUNTS ON
SUNDAY. ON FRIDAY...EXPECT 05-10MM/DAY AND MAXIMA OF 15-25MM FROM
WESTERN PANAMA INTO SOUTHEAST NICARAGUA. ON SATURDAY THIS PEAKS AT
10-15MM/DAY AND ISOLATED MAXIMA OF 20-35MM FROM BOCAS DEL TORO
INTO NORTHEAST COSTA RICA. IN EASTERN NICARAGUA AND EASTERN
HONDURAS EXPECT 05-10MM/DAY AND ISOLATED MAXIMA OF 15-20MM. ON
SUNDAY...EXPECT 05-10MM/DAY AND MAXIMA OF15MM PRIMARILY IN BOCAS
DEL TORO AND BETWEEN TORTUGUERO AND BLUEFIELDS. ALSO IN CENTRAL
AMERICA...EXPECT AN INCREASE IN BELIZE AND
GUATEMALA/CHIAPAS/QUINTANA ROO BY SUNDAY AIDED BY A LOW-LEVEL
PREFRONTAL TROUGH STRUCTURE AND AN INCREASE IN THE NORTHEASTERLY
COMPONENT OF THE WIND. THIS WILL FAVOR AN INCREASE IN LOW-LEVEL
CONVERGENCE AND TRIGGER AMOUNTS OF 05-10MM/DAY AND ISOLATED MAXIMA
OF 15-20MM.
IN NORTHERN SOUTH AMERICA AND IN THE UPPER LEVELS...A RIDGE IS
FORECAST TO MEANDER OVER COLOMBIA DURING MOST OF THE CYCLE...WHILE
A TROUGH WILL PERSIST ACROSS EASTERN VENEZUELA AND THE WESTERN
GUIANAS. THE UPPER TROUGH IS FORECAST TO SLOWLY RETROGRADE INTO
EASTERN VENEZUELA/RORAIMA BY SUNDAY. THIS WILL FAVOR A SEASONALLY
ACTIVE PATTERN OF DIURNAL CONVECTION IN THE GUIANAS...AS THE
REGION REMAINS IN THE UPPER DIVERGENT SIDE OF THIS TROUGH.
MOISTURE WILL CONTINUE TO BE PROVIDED BY PERTURBATIONS PROPAGATING
ALONG THE ATLANTIC ITCZ...HOWEVER...FAST TRADES WILL ENHANCE
LOW-LEVEL SHEAR TO LIMIT POTENTIAL ACCUMULATIONS. ON
FRIDAY...EXPECT 10-15MM/DAY AND MAXIMA OF 20-35MM IN COASTAL AREAS
WHILE INLAND EXPECT 10-15MM/DAY AND MAXIMA OF 20-30MM.
ONSATURDAY...EXPECT A PEAK IN ACTIVITY IN COASTAL GUYANA WHERE
AMOUNTS ARE FORECAST TO REACH 15-20MM/DAY AND ISOLATED MAXIMA OF
30-60MM. ELSEWHERE IN COASTAL AREAS EXPECT 10-15MM/DAY AND
ISOLATED MAXIMA OF 20-40MM. ON SUNDAY...EXPECT THE LARGEST AMOUNTS
IN AMAPA/EASTERN FRENCH GUIANA WHERE ITCZ CONVERGENCE WILL FAVOR
10-15MM/DAY AND MAXIMA OF 20-45MM. IN AREAS TO THE WEST EXPECT
10-15MM/DAY AND MAXIMA OF 20-35MM. IN COLOMBIA...THE HEAVIEST
PRECIPITATION IS EXPECTED IN WESTERN AND SOUTHWESTERN PORTIONS DUE
TO ENHANCED MOISTURE CONVERGENCE BY WESTERLIES IN THE PACIFIC
BASIN. EXPECT AN INCREASE FROM 10-15MM/DAY AND MAXIMA OF 20-45MM
ON FRIDAY TO 15-20MM/DAY AND MAXIMA OF 25-50MM ON SATURDAY. THIS
THEN DECREASES TO 10-15MM/DAY AND MAXIMA OF 20-35MM.
TROPICAL WAVES/TUTT INDUCED PERTURBATIONS/TRADE WIND SURGES
INITIALIZED AT 12 UTC:
NONE
GALVEZ/ACOSTA/CHINCHILLA...WPC (USA)
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