486
FXCA20 KWBC 221808
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
108 PM EST THU DEC 22 2022
NOTE: AN ARCTIC OUTBREAK IS ON THE WAY ACROSS THE CENTRAL AND
EASTERN USA AS A POTENT UPPER TROUGH DEEPENS INTO THE NORTHERN USA
FROM WESTERN CANADA ON WEDNESDAY. THE ASSOCIATED SURFACE FRONT
WILL MAKE IT INTO THE NORTHWEST CARIBBEAN ON FRIDAY/SATURDAY...TO
FAVOR COOL TEMPERATURES EXTENDING INTO NORTHERN CENTRAL
AMERICA...CENTRAL CUBA AND THE CENTRAL BAHAMAS FROM DECEMBER 24TH
THROUGH AT LEAST THE 27TH.
FORECAST BULLETIN FROM 21 DEC 2022 AT 18 UTC: A BROAD UPPER RIDGE
EXTENDS FROM A HIGH OVER SOUTHERN CENTRAL AMERICA INTO THE
SOUTHERN GULF OF MEXICO AND THE NORTHERN CARIBBEAN. THIS WILL
LIMIT THE SOUTHWARD PROGRESSION OF UPPER TROUGHS IN THE WESTERLIES
GENERALLY TO AREAS TO THE NORTH OF 25N.IN THE LOW-LEVELS...TWO
FRONTS EXTEND IN NORTHERN PORTIONS OF THE DOMAIN. OVER THE GULF OF
MEXICO...ON WEDNESDAY EVENING...EXPECT A BOUNDARY TO EXTEND FROM
CENTRAL FLORIDA...INTO A LOW NEAR 26N 89W...INTO CENTRAL VERACRUZ.
THIS FRONT IS FORECAST TO REAPIDLY WEAKEN WITH LIMITED EFFECTS IN
CONTINENTAL AREAS. ANOTHER FRONT EXTENDS ZONALLY FROM THE NORTH
ATLANTIC INTO THE CENTRAL BAHAMAS AND THE FLORIDA STRAIT ON
WEDNESDAY. THIS BOUNDARY IS FORECAST TO WEAKEN RAPIDLY AS
WELL...WHILE EXITING INTO THE ATLANTIC. A MUCH MORE SIGNIFICANT
FRONT IS FORECAST TO RAPIDLY ARRIVE FROM THE NORTH ON
THURSDAY...IN ASSOCIATION WITH A POTENT ARCTIC OUTBREAK ACROSS THE
CENTRAL AND EASTERN USA. BY THURSDAY EVENING...THE ARCTIC FRONT IS
EXPECTED ACROSS LOUISIANA...NORTHERN TAMAULIPAS...WESTERN
COAHUILA. ON FRIDAY EVENING...THE BOUNDARY WILL RAPIDLY MOVE
SOUTHWESTWARD TO EXTEND INTO 30N 70W...THE NORTHWEST
BAHAMAS...WESTERN CUBA...CENTRAL QUINTANA ROO...THE TEHUANTEPEC
ISTHMUS AND ALONG THE SIERRA MADRE ORIENTAL INTO CENTRAL DURANGO
AND CENTRAL CHIHUAHUA. A SHEAR LINE IS ALSO EXPECTED TO FORM ON
FRIDAY...TO EXTEND ACROSS THE SOUTHEAST BAHAMAS...WINDWARD
PASSAGE...EXTREME NORTHWEST JAMAICA...EXTREME NORTHEAST
NICARAGUA...CENTRAL NICARAGUA ON FRIDAY EVENING. THE SHEAR LINE IS
FORECAST TO BECOME BETTER DEFINED ON CHRISTMAS DAY...TO REMAIN
NEARLY STATIONARY OR START RETREATING NORTHWARD INTO THE EASTERN
GULF OF HONDURAS. OF IMPORTANCE IS A POTENT NORTES EVENT ON
FRIDAY...AS THE FRONT AND TIGHT PRESSURE GRADIENT APPROACH THE
SOUTHWEST GULF OF MEXICO. MODELS ARE SUGGESTING SPEEDS OF 50-60KT
PEAKING ON FRIDAY EVENING. A TEHUANTEPECER LOW-LEVEL JET IS ALSO
EXPECTED TO DEVELOP LATE ON FRIDAY...TO REACH SPEEDS OF 60-70KT
DURING SATURDAY.
IN TERMS OF PRECIPITATION...THE FRONT WILL FAVOR LARGE VALUES OF
MOISTURE CONVERGENCE AS THE NORTES INTERACT WITH THE OROGRAPHY OF
SOUTHERN MEXICO ON FRIDAY. THIS WILL FAVOR 15-30MM/DAY AND MAXIMA
OF 40-80MM IN SOUTHERN VERACRUZ/CHIAPAS/TABASCO...WHILE ALONG THE
SIERRA MADRE ORIENTAL/COASTAL PLAIN EXPECT 10-15MM/DAY AND MAXIMA
OF 20-35MM. FRONTAL CONVECTION INTERACTING WITH ENHANCED UPPER
DYNAMICS IN THE BASE OF THE UPPER TROUGH WILL FAVOR 10-15MM/DAY
AND MAXIMA OF 20-45MM WITH A SLIGHT RISK OF SEVERE CONVECTION IN
THE EXTREME NORTHEAST YUCATAN PENINSULA AND EXTREME WESTERN CUBA
ON FRIDAY THROUGH SATURDAY MORNING. IN CENTRAL CUBA AND IN THE
NORTHWEST BAHAMAS EXPECT 05-10MM/DAY AND MAXIMA OF 15-20MM ALSO
WITH A SLIGHT RISK OF SEVERITY. IN THE CENTRAL/WESTERN YUCATAN
PENINSULA EXPECT 05-10MM/DAY AND MAXIMA OF 15-20MM. ENHANCED
MOISTURE CONVERGENCE BY THE NORTHEASTERLY TRADES IN
CHIAPAS...CENTRAL GUATEMALA AND BELIZE WILL FAVOR 10-15MM/DAY AND
MAXIMA OF 20-35MM. ALSO ON FRIDAY...THE SHEAR LINE WILL FAVOR
10-15MM/DAY AND MAXIMA OF 20-35MM IN NORTHEAST HONDURAS AND
NORTHEAST NICARAGUA.
TO THE SOUTH...LIMITED AVAILABLE MOISTURE WILL CONTINUE TO FAVOR
GENERALLY FAIR WEATHER CONDITIONS IN MOST OF THE
CARIBBEAN...CENTRAL AMERICA AND NORTHERN SOUTH AMERICA.
HOWEVER...THE PERSISTENCE OF THE CARIBBEAN LOW-LEVEL JET WILL
MAINTAIN SCATTERED CONVECTION ON ADAILY BASIS IN THE CARIBBEAN
BASIN OF COSTA RICA/PANAMA AND SOUTHEAST NICARAGUA. INITIALLY
EXPECT 05-10MM/DAY AND MAXIMA OF 15MM IN BOCAS DEL TORO. THIS
INCREASES TO 10-15MM/DAY AND MAXIMA OF 20-35MM FROM BOCAS DEL TORO
INTO SOUTHEAST NICARAGUA. IN COSTA RICA...NOTE AN INCREASE IN THE
POTENTIAL FOR SPILLOVER/DERRAME INTO THE CENTRAL VALLEY ON FRIDAY.
IN NORTHERN SOUTH AMERICA...THE MOST SIGNIFICANT CONVECTION WILL
CLUSTER IN THE AMAZON BASIN GIVEN FAST NORTHEASTERLY TRADES ACROSS
THE GUIANAS...TRANSPORTING A DRIER AND MORE STABLE AIR MASS FROM
THE TROPICAL NORTH ATLANTIC. ANY DIURNAL CONVECTION WILL PRIMARILY
CLUSTER IN FRENCH GUIANA AND SOUTHEAST SURINAME...WHERE EXPECT
ISOLATED MAXIMA OF 15-25MM ON WENDESDAY...AND 20-45MM ON
THURSDAY...DECREASING AFTER. IN COLOMBIA...ANY ACTIVITY WILL OCCUR
IN A VERY ISOLATED MANNER...AND GENERALLY CLUSTER TO WESTERN
COLOMBIA/EJE CAFETERO...PRODUCING 05-10MM/DAY AND MAXIMA OF 15MM
ON WEDNESDAY AND THURSDAY...INCREASING TO MAXIMA OF 15-25MM ON
FRIDAY.
TROPICAL WAVES/TUTT INDUCED PERTURBATIONS/TRADE WIND SURGES
INITIALIZED AT 12 UTC:
NONE
GALVEZ/CHINCHILLA...WPC (USA)
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