267
FXCA20 KWBC 091931
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
231 PM EST THU JAN 09 2025

FORECAST BULLETIN 09 JANUARY 2025 AT 19 UTC

A POTENT UPPER TROUGH EXTENDS FROM COLORADO AND ACROSS NORTHERN
CHIHUAHUA INTO SOUTHERN PORTIONS OF BAJA CALIFORNIA SUR. THIS
TROUGH ASSOCIATES WITH AN UPPER JET STREAK THAT EXTENDS FROM
SOUTHERN BAJA CALIFORNIA SUR ACROSS SOUTHEAST CHIHUAHUA INTO THE
PLAINS OF THE USA. THIS ASSOCIATES WITH IMPORTANT VORTICITY MAXIMA
IN THE MID-LEVELS...WHICH WILL HAVE AN IMPACT IN THE DEVELOPMENT
OF ASCENT AND ASSOCIATED PRECIPITATION IN PORTIONS OF NORTHWEST
AND WEST-CENTRAL MEXICO. THE UPPER TROUGH IS SUFFICIENTLY COLD
THAT IS GENERATING AN UNSTABLE ENVIRONMENT AND SNOWFALL IN
PORTIONS OF CHIHUAHUA ON THURSDAY. FURTHERMORE...THE SYSTEM
ASSOCIATES WITH A SURFACE COLD FRONT AND ATMOSPHERIC RIVER-LIKE
PLUME THAT IS HIGHLIGHTING PRECIPITATION IN SOUTHERN PORTIONS OF
THE SIERRA MADRE OCCIDENTAL ON THURSDAY. THE UPPER TROUGH IS
REACHING MAXIMUM AMPLITUDE TODAY AND IS FORECAST TO GRADUALLY
WEAKEN THROUGH THE FORECAST CYCLE. SIMILARLY...THE FRONT IS
EXPECTED TO LOSE DEFINITION THROUGH FRIDAY MORNING...YIELDING TO A
DECREASE IN PRECIPITATION. THROUGH EARLY FRIDAY EXPECT ADDITIONAL
SNOWFALL MAXIMA OF 10 - 15CM IN ELEVATED TERRAIN OF WESTERN
CHIHUAHUA...WHILE IN CENTRAL CHIHUAHUA EXPECT MAXIMA OF 02 - 06CM.
IN THE SIERRA MADRE OF SINALOA/WESTERN DURANGO/NORTHERN
NAYARIT...MOIST INFLOW FROM THE TROPICAL PACIFIC/ATMOSPHERIC
RIVER-LIKE PLUME WILL FAVOR MAXIMA OF 40-80MM. EXPECT A NOTICEABLE
DECREASE IN ACCUMULATION THEREAFTER.

A FRONTAL LOW IS ORGANIZING IN THE COAST OF TEXAS ON THURSDAY.
MODELS AGREE THAT THE LOW WILL MIGRATE RAPIDLY TOWARDS THE
SOUTHEAST USA BY FRIDAY EVENING...WHEN THE COLD FRONT IS FORECAST
ACROSS THE CENTRAL GULF OF MEXICO...CENTRAL VERACRUZ...SOUTHERN
HIDALGO IN MEXICO. BY SATURDAY EVENING EXPECT THE FRONT JUST TO
THE NORTH OF THE FAR NORTHWEST BAHAMAS...SOUTH FLORIDA...INTO A
WEAKENING STATIONARY BOUNDARY EXTENDING INTO THE NORTH-CENTRAL
YUCATAN PENINSULA AND SOUTHERN CHIAPAS/NORTHERN GUATEMALA. IN THE
MID-LEVELS...A ROBUST RIDGE IS FORECAST TO ROLL FROM BELIZE ON
THURSDAY TO CENTER OVER HISPANIOLA BY SATURDAY EVENING...WHILE
STRENGTHENING AND STILL SUSTAINING A TRADE WIND CAP OVER NORTHERN
CENTRAL AMERICA AND SOUTHERN MEXICO. THIS WILL LIMIT RAINFALL
ACCUMULATION WITH THIS FRONT...TO FAVOR MAXIMA GENERALLY BELOW
15MM IN THE GULF OF MEXICO BASIN.

AN ELONGATED COLD FRONT... CURRENTLY ACROSS CENTRAL
HISPANIOLA...JUST SOUTH OF JAMAICA INTO FAR SOUTHEAST
NICARAGUA...AND IS SLOWLY WEAKENING. BY FRIDAY EVENING... THE
WEAKENING COLD FRONT WILL BE ACROSS ANTIGUA AND BARBUDA/
GUADELOUPE. IN AREAS TO THE WEST...THE BOUNDARY IS BEING ANALYZED
AS A FRONTAL SHEAR LINE TO EXTEND ALONG 15N INTO SAN ANDRES AND
NORTH COSTA RICA. ANOTHER COLD FRONT IS DEVELOPING EAST OF
FLORIDA. BY THIS EVENING... THIS COLD FRONT WILL BE ACROSS CENTRAL
BAHAMAS. BY FRIDAY EVENING... IT WILL BE LOCATED JUST NORTH OF
PUERTO RICO AND ACROSS NORTHERN HISPANIOLA. BY SATURDAY EVENING...
IT WILL MERGE WITH THE PREVIOUS FRONT AND BECOME STATIONARY FRONT
WHILE EXTENDING INTO GUADELOUPE. THE MOST SIGNIFICANT RAINFALL
IMPACTS ARE EXPECTED IN NORTHERN COSTA RICA AND SOUTHEAST
NICARAGUA ON THURSDAY...WHERE EXPECT MAXIMA OF 20 - 45MM. EXPECT A
GRADUAL DECREASE IN AMOUNTS THEREAFTER.  IN THE EASTERN
CARIBBEAN...THE INFLUENCE OF THE MID-LEVEL RIDGE AND LOW VALUES OF
AVAILABLE MOISTURE WILL YIELD TO VERY CONSERVATIVE RAINFALL
AMOUNTS WITH THESE FRONTS.

IN SOUTH AMERICA...THE HEAVIEST PRECIPITATION WILL CLUSTER IN
REGIONS OF ITCZ CONVERGENCE...GENERALLY IN SOUTHWEST COLOMBIA AND
IN AMAPA-BRASIL. VENTILATION IN THE UPPER TROPOSPHERE IS
DECREASING WITH RESPECT TO PREVIOUS DAYS...FURTHERMORE...ENHANCED
WIND SHEAR IN THE MIDDLE TROPOSPHERE WILL GENERALLY LIMIT
ACCUMULATIONS ALONG THE ANDEAN REGION OF COLOMBIA AN ECUADOR. IN
TERMS OF RAINFALL AMOUNTS IN THE PACIFIC BASIN...EXPECT MAXIMA OF
15 - 30MM THROUGH EARLY FRIDAY DECREASING GRADUALLY TO MAXIMA OF
15 - 20MM BY SATURDAY. IN THE ATLANTIC...A PROPAGATING LOW-LEVEL
TROUGH WILL PLAY A ROLE IN ENHANCING PRECIPITATION IN THE GUIANAS
AS THE CYCLE PROGRESSES. THROUGH EARLY FRIDAY EXPECT MAXIMA OF
15-30MM IN FRENCH GUIANA AND AMAPA...SPREADING WEST INTO EASTERN
GUYANA AND SURINAME WHILE DECREASING TO MAXIMA GENERALLY OF 15 -
25MM BY SATURDAY THROUGH EARLY SUNDAY.

GALVEZ...(WPC)
TINOCO...(WPC)




















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