608
FXCA20 KWBC 201944
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
244 PM EST TUE DEC 20 2022
FORECAST BULLETIN FROM 20 DEC 2022 AT 18 UTC: NORTH IN THE
DOMAIN...A SHORT WAVE TROUGH EXTENDS ACROSS THE MISSISSIPPI VALLEY
INTO THE NORTHWEST GULF OF MEXICO ON TUESDAY. THIS SYSTEM LIES
WEST OF AN UPPER RIDGE...AND IT IS ASSOCIATED WITH THE DIVERGENT
ENTRANCE OF AN UPPER JET ALONG THE DIVERGENT/EAST SIDE OF THE
UPPER TROUGH. AS SUCH...THE TROUGH WILL CONTINUE TO ENHANCE
DYNAMICAL ASCENT IN THE MID-UPPER TROPOSPHERE...TO FAVOR HEAVY
RAINFALL AS IT PROGRESSES ACROSS FLORIDA INTO THE NORTHWEST
BAHAMAS LATE ON TUESDAY/EARLY ON WEDNESDAY. IN THE MEAN TIME...TWO
TRAINS OF SURFACE FRONTS EXTENDS IN NORTHERN PORTIONS OF THE
BASIN. THE SOUTHERN TRAIN WILL AFFECT THE BAHAMAS AND PORTIONS OF
SOUTHERN MEXICO EARLY IN THE CYCLE. ON TUESDAY EVENING THIS IS
EXPECTED ALONG THE NORTHWEST BAHAM,AS...SOUTH FLORIDA...CENTRAL
VERACRUZ AND ALONG THE SIERRA MADRE ORIENTAL/EASTERN MEXICAN
PLATEAU. BY WEDNESDAY EVENING THIS BOUNDARY WILL CONTINUE TO
EXTEND ACROSS THE NORTHWEST BAHAMAS AND INTO THE FLORIDA STRAIT
WHILE WEAKENING. THE BOUNDARY EXITS THE FORECAST AREA THEREAFTER.
IN TERMS OF PRECIPITATION...EXPECT 10-15MM/DAY AND MAXIMA OF
20-40MM IN VERACRUZ ON TUESDAY...ENHANCED BY 30-35KT NORTES AND
OROGRAPHY. PREFRONTAL NORTHEASTERLY TRADES IN NORTHENR CENTRAL
AMERICA WILL FAVOR 05-10MM/DAY AND MAXIMA OF 15MM. ALSO ON TUESDAY
THROUGH EARLY WEDNESDAY...THE POTENT SHORT WAVE TROUGH/UPPER JET
ENTRANCE WILL INTERACT WITH THE SURFACE FRONT IN THE NORTHWEST
BAHAMAS OVERNIGHT...TO PRODUCE HEAVY RAINFALL. IN GRAND BAHAMA AND
NORTHERN ABACO EXPECT 20-30MM/DAY AND ISOLATED MAXIMA OF 50-100MM
IN SEVERE CONVECTION ELSEWHERE IN THE NORTHWEST BAHAMAS EXPECT
05-10MM/DAY AND MAXIMA OF 15-25MM. ON WEDNESDAY...AS THE SYSTEM
WEAKENS...EXPECT REMNANT CONVECTION TO PRODUCE 05-10MM/DAY AND
ISOLATED MAXIMA OF 15-25MM IN THE NORTHWEST BAHAMAS AND IN
SOUTHERN MEXICO.
ALSO OF RELEVANCE...A POTENT POLAR OUTBREAK IS EXPECTED ACROSS THE
CENTRAL AND EASTERN USA LATER THIS WEEK. THE POLAR HIGH FORMING IN
THE WESTERN PLAINS OF THE USA WILL FAVOR A RAPID SOUTHWARD
PROGRESSION OF THE ARCTIC FRONT...WHICH ON THURSDAY EVENING...IS
FORECAST TO EXTEND ACROSS LOUISIANA...THE RIO BRAVO...CENTRAL
COAHUILA. BY FRIDAY EVENING THE FRONT IS FORECAST ACROSS THE
CENTRAL BAHAMAS...CENTRAL CUBA...CENTRAL YUCATAN PENINSULA INTO
THE TEHUANTEPEC ISTHMUS AND CENTRAL PORTIONS OF THE MEXICAN
PLATEAU. THIS SYSTEM WILL PRODUCE LIMITED PRECIPITATION
INITIALLY...GIVEN A DRY AIR MASS IN PLACE IN THE NORTHERN GULF OF
MEXICO. YET...THE RAPID PROPAGATION OF THE FRONT WILL FAVOR
SQUALLY WEATHER DEVELOPING LATE ON THURSDAY INTO FRIDAY MORNING
FROM THE EXTREME NORTHEAST YUCATAN PENINSULA INTO THE FLORIDA
STRAIT AND THE NORTHWEST BAHAMAS. THIS WILL FAVOR ISOLATED AMOUNTS
OF 05-10MM/DAY AND MAXIMA OF 15-25MM. OF CONCERN IS THE LARGE
PRESSURE GRADIENT ASSOCIATED WITH THIS COLD AIR BLAST. THIS
GRADIENT WILL FAVOR THE DEVELOPMENT OF A STRONG NORTES EVENT ON
FRIDAY...WITH FORECAST WINDS OF 40-55KT ALONG THE COASTS AND
COASTAL PLAIN OF VERACRUZ. IT WILL THEN FAVOR THE DEVELOPMENT OF A
TEHUAPTEPECER LOW-LEVEL JET...WITH FORECAST SPEEDS IN THE 55-65KT
RANGE DURING FRIDAY AND SATURDAY.
THE MID-LEVEL RIDGE EXPECTED TO PERSIST ACROSS THE ENTIRE NORTHERN
CARIBBEAN THROUGH THE FORECAST CYCLE WILL CONTINUE TO LIMIT
PRECIPITATION AMOUNTS AND COVERAGE. THE ONLY REGION OF INTEREST IS
THE CARIBBEAN BASIN OF PANAMA AND COSTA RICA/SOUTHEAST NICARAGUA
TO A LESSER EXTENT. HERE...THE SEASONAL ACCELERATION OF THE
CARIBBEAN LOW-LEVEL JET WILL SUSTAIN ENHANCED MOISTURE CONVERGENCE
ON A DAILY BASIS TO FAVOR A DECREASING TREND IN AMOUNTS. INITIALLY
EXPECT 05-10MM/DAY AND MAXIMA OF 15MM...INCREASING TO 10-15MM/DAY
AND MAXIMA OF 20-35MM.
A RAPID WET-TO-DRY TRANSITION CONTINUES IN NORTHERN SOUTH
AMERICA...WHERE THE ITCZ/NET IS RAPIDLY MEANDERING SOUTHWARD IN
RESPONSE TO INCREASING SURFACE PRESSURES IN THE ATLANTIC. THIS
WILL FAVOR A DRYING TREND IN THE GUIANAS THROUGH THE CYCLE...AND
WILL CONTINUE TO LIMIT PRECIPITATION AMOUNTS IN COLOMBIA. THE
LARGEST ACCUMULATIONS ARE ASSOCIATED WITH ITCZ CONVERGENCE IN THE
ATLANTIC. THIS WILL FAVOR 15-20MM/DAY AND MAXIMA OF 25-50MM ON
TUESDAY AND WEDNESDAY IN AMAPA AND EASTERN FRENCH GUIANA. THIS
INCREASES TO 15-20MM/DAY AND MAXIMA OF 35-70MM ON THURSDAY...BUT
THE AREA WILL CONSTRAIN TO BRASIL AS THE ITCZ MEANDERS TO THE
SOUTH. INLAND EXPECT GENERALLY 10-15MM/DAY AND MAXIMA OF 20-35MM.
TROPICAL WAVES/TUTT INDUCED PERTURBATIONS/TRADE WIND SURGES
INITIALIZED AT 12 UTC:
NONE
GALVEZ/CHINCHILLA...WPC (USA)
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