768
FXCA20 KWBC 051952
PMDCA
TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
252 PM EST MON JAN 05 2026
FORECAST BULLETIN 05 JANUARY 2026 AT 2000 UTC:
A MID-TO-UPPER LEVEL TROUGH THAT IS CURRENTLY SITUATED OFF THE
WEST COAST OF THE UNITED STATES WILL CONTINUE TO AMPLIFY AND
DEVELOP A POSITIVE TILT. BY EARLY WEDNESDAY MORNING, THIS TROUGH
WILL BEGIN TO OCCLUDE OFF THE SOUTHERN COAST OF CALIFORNIA AND
WILL CONTINUE PROPAGATING SOUTHEASTWARD INTO NORTHWEST MEXICO. THE
AXIS OF THE MID-TO-UPPER LEVEL OCCLUSION WILL BE OVER BAJA
CALIFORNIA BY WEDNESDAY MORNING AND WILL BE ACCOMPANIED BY A JET
STREAK MAX ALONG THE EXIT REGION OF THE TROUGH THAT IS EMBEDDED
WITHIN THE SUBTROPICAL JET STREAM. THIS MID-TO-UPPER LEVEL
OCCLUSION WILL WEAKEN SIGNIFICANTLY AS IT BEGINS TO MOVE IN-LAND.
REGARDLESS, EXPECT AN ENHANCEMENT IN UPPER LEVEL DIVERGENCE WITH
THIS UPPER LEVEL PATTERN ACROSS NORTHWESTERN MEXICO FOR WEDNESDAY.
AT THE SURFACE, EXPECT THE SOUTHEASTWARD ADVANCEMENT OF AN
OCCLUDED FRONT AND COLD FRONT THAT WILL BE LOCATED ACROSS THE
CENTRAL REGION OF BAJA CALIFORNIA SUR AND EXTENDING OFF COAST INTO
THE PACIFIC. THE COUPLING OF THE DYNAMIC MID-TO-UPPER LEVEL
PATTERN, THE PRESENCE OF THE TROPICAL MOIST AIR, AND THE FRONTAL
SYSTEM WILL FAVOR THE INCREASE IN PRECIPITATION CHANCES ACROSS THE
CENTRAL REGIONS OF THE BAJA CALIFORNIA PENINSULA. THUS, TOTAL
RAINFALL ACCUMULATIONS OF 20 - 40MM ARE POSSIBLE FROM WEDNESDAY
MORNING THROUGH THURSDAY MORNING. THE MOISTURE PLUME ALSO WILL
EXTEND INTO SONORA AND THE GULF COAST OF BAJA CALIFORNIA AND WILL
ASSIST IN THE INCREASE IN MOISTURE CONVERGENCE. A TOTAL
PRECIPITATION MAXIMA OF 15 - 30MM IS LIKELY FOR THE SAME TIME
PERIOD. ANOTHER COLD FRONT WILL BE DEVELOPING ON THE LEEWARD SIDE
OF THE SIERRA MADRE ORIENTAL IN CHIHUAHUA DUE TO THE PRESENCE OF
THE AFOREMENTIONED MID-TO-UPPER LEVEL TROUGH. MOISTURE WILL BE
LIMITED IN THIS REGION BUT ACCUMULATIONS OF UP TO 10MM ARE
POSSIBLE ACROSS NORTHERN CHIHUAHUA FOR WEDNESDAY.
ANOTHER MID-TO-UPPER LEVEL FEATURE OF INTEREST IS AN UPPER LEVEL
TROUGH THAT IS EXTENDING ACROSS THE NORTHERN CARIBBEAN. THE AXIS
OF THIS TROUGH WILL BE MOVING ACROSS HISPANIOLA DURING THE DAY ON
MONDAY AND WILL PROMOTE THE ENHANCEMENT OF UPPER LEVEL DIVERGENCE
AND INCREASING INSTABILITY. AT THE SAME TIME, A DECAYED FRONTAL
SYSTEM THAT HAS TRANSITIONED INTO A SURFACE TROUGH WILL BE MOVING
INTO THE ISLAND ON MONDAY AND WILL FAVOR INCREASING SURFACE ASCENT
AND MOISTURE CONVERGENCE. THESE CONDITIONS WILL FAVOR THE
DEVELOPMENT FOR THUNDERSTORMS DURING THE DAY ON MONDAY. THUS,
TOTAL RAINFALL ACCUMULATIONS WILL RANGE BETWEEN 15 TO 25MM FROM
MONDAY MORNING THROUGH TUESDAY MORNING ACROSS HISPANIOLA WITH A
DRYING TREND AFTER MONDAY NIGHT.
AS THIS MID-TO-UPPER LEVEL TROUGH CONTINUES TO MOVE EASTWARD
DURING THE NIGHT ON MONDAY, A SURFACE-TO-LOW LEVEL TROUGH WILL
MOVE INTO PUERTO RICO, THE VIRGIN ISLANDS, AND THE LEEWARD ISLANDS
OF THE LESSER ANTILLES. ALSO EXPECT AN INCREASE IN MOISTURE IN
THIS REGION. SHOWERS AND THUNDERSTORMS THAT DEVELOP WILL BE
FURTHER ENHANCED BY THE DIURNAL CYCLE. A TOTAL PRECIPITATION
MAXIMA OF 15 - 20MM IS EXPECTED ACROSS THE AFOREMENTIONED REGIONS
FROM MONDAY MORNING THROUGH TUESDAY MORNING. BY TUESDAY, THE
MID-TO-UPPER LEVEL TROUGH WILL CONTINUE MOVING INTO THE ATLANTIC
WHILE MID-LEVEL TROUGHING WILL STILL PERSIST ACROSS THE LEEWARD
ISLANDS OF THE LESSER ANTILLES. THIS MID-LEVEL TROUGH IS BEING
SUSTAINED BY THE PRESENCE OF AN UPPER JET STREAK MAX IN THE
REGION. THIS MID-LEVEL TROUGH WILL CONTINUE TO PROMOTE ASCENT IN
THE REGION AND WILL ALSO PROMOTE THE COOLING OF THE MID-LEVELS.
THE DEVELOPMENT OF THUNDERSTORMS IS POSSIBLE IN THE REGION AND A
TOTAL PRECIPITATION MAXIMA OF 15 - 20MM IS LIKELY ACROSS THE
LEEWARD ISLANDS FROM TUESDAY MORNING THROUGH WEDNESDAY MORNING.
ACROSS THE PACIFIC COASTS OF COLOMBIA AND PERU, EXPECT THE
DEVELOPMENT OF A LOW LEVEL TROUGH WHERE THERE WILL ALSO BE AN
INCREASE IN LOW LEVEL MOISTURE. THE DIURNAL CYCLE AND LOCAL
EFFECTS WILL FURTHER ENHANCE PRECIPITATION CHANCES. THERE WILL BE
A GRADUAL DAILY INCREASE IN THE TOTAL PRECIPITATION MAXIMA IN THIS
REGION, WITH THE HIGHEST ACCUMULATIONS OCCURRING FROM TUESDAY
MORNING INTO WEDNESDAY MORNING. ELSEWHERE IN TROPICAL SOUTH
AMERICA, THE PRESENCE OF LOW LEVEL TROUGHS WILL CONTRIBUTE TO
INCREASING SURFACE-TO-MID LEVEL MOISTURE CONVERGENCE AND ASCENT
THAT WILL HELP TRIGGER CONVECTION ACROSS THE ENTIRE REGION. IN THE
UPPER LEVELS, A DIFFLUENT PATTERN WILL BE PERSISTENT ACROSS THE
WESTERN AMAZON BASIN AND THIS WILL FAVOR THE SUSTENANCE OF UPPER
DIVERGENCE IN THIS REGION WHICH WILL FURTHER PROMOTE THE
DEVELOPMENT FOR CONVECTION.
ACROSS THE REST OF THE BASIN, SEASONAL CONDITIONS WILL PREVAIL.
LOCAL EFFECTS AND THE DIURNAL CYCLE WILL CONTINUE TO FAVOR THE
DEVELOPMENT OF LOCALIZED PRECIPITATION FOR THE NEXT THREE DAYS.
TINOCO-MORALES...(WPC)
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