401
FXUS01 KWBC 160735
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
235 AM EST MON DEC 16 2024
VALID 12Z MON DEC 16 2024 - 12Z WED DEC 18 2024
...MODEST ATMOSPHERIC RIVER ACTIVITY TO BRING UNSETTLED WEATHER TO
THE NORTHWEST, INCLUDING HEAVY RAINS FOR THE COASTAL RANGES AND
ACCUMULATING SNOW FOR THE HIGHER ELEVATIONS...
...WET CONDITIONS EXPECTED FOR MUCH OF THE EASTERN HALF OF THE
COUNTRY THE NEXT COUPLE OF DAYS...
...ABOVE AVERAGE TEMPERATURES, MILD CONDITIONS EXPECTED FOR MUCH
OF THE COUNTRY TO START THE WEEK...
A PAIR OF PACIFIC SYSTEMS WILL HELP TO FOCUS A FLOW OF MOISTURE
OVER THE NORTHWEST IN AN ACTIVE ATMOSPHERIC RIVER PATTERN THE NEXT
COUPLE OF DAYS. PRECIPITATION CONTINUES THIS MORNING AS MOISTURE
FLOWS INLAND FROM THE FIRST SYSTEM BRINGING MODERATE TO HEAVY
COASTAL RAIN, AN INLAND WINTRY MIX, AND HEAVY HIGHER ELEVATION
MOUNTAIN SNOW ACROSS THE PACIFIC NORTHWEST, NORTHERN CALIFORNIA,
AND THE NORTHERN GREAT BASIN/ROCKIES. THE HEAVIEST PRECIPITATION
WILL BE FOCUSED SOUTHWARD TODAY ACROSS OREGON/NORTHERN CALIFORNIA
AND INLAND THROUGH CENTRAL IDAHO INTO NORTHWEST WYOMING. THE FOCUS
WILL SHIFT NORTHWARD ON TUESDAY BRINGING HEAVIER RAIN TO COASTAL
WASHINGTON STATE AS WELL AS HEAVY SNOW TO THE NORTHERN CASCADES.
SNOW TOTALS OF 4-8" WILL BE COMMON WITH LOCALLY HIGHER TOTALS OVER
A FOOT FOR THE HIGHEST PEAKS EXPECTED, PARTICULARLY FOR THE
SOUTHERN CASCADES IN OREGON MONDAY.
TO THE EAST, LIGHT TO MODERATE RAINFALL CONTINUES THIS MORNING
OVER THE MID-ATLANTIC WITH SOME WINTRY PRECIPITATION OVER THE
INTERIOR NORTHEAST, WHICH SHOULD TAPER OFF THROUGH EARLY
AFTERNOON. A MORE FOCUSED CORRIDOR OF SHOWERS AND THUNDERSTORMS
WILL REDEVELOP THROUGH THE DAY AHEAD OF A COLD FRONT OVER THE OHIO
VALLEY SOUTHWESTWARD THROUGH THE LOWER MISSISSIPPI VALLEY/SOUTHERN
PLAINS. SOME MODERATE TO LOCALLY HEAVY RAINFALL WILL BE POSSIBLE,
PARTICULARLY FOR THE OHIO VALLEY. THIS SYSTEM WILL BRING ANOTHER
WAVE OF RAIN THROUGH THE MID-ATLANTIC MONDAY EVENING AND NEW
ENGLAND TUESDAY MORNING, WITH A WINTRY MIX POSSIBLE FOR INTERIOR
LOCATIONS. AN APPROACHING UPPER-LEVEL WAVE WILL HELP TO KICK OFF
ANOTHER ROUND OF SHOWERS AND STORMS ALONG THE FRONTAL BOUNDARY
FROM THE OHIO VALLEY SOUTHWEST THROUGH THE SOUTHERN PLAINS
TUESDAY.
ELSEWHERE, AN UPPER-LEVEL WAVE PASSING OVER THE NORTHERN
PLAINS/UPPER MIDWEST WILL BRING SOME SNOW SHOWERS ON TUESDAY WITH
SOME LIGHT ACCUMULATIONS POSSIBLE. SOME LAKE EFFECT SNOW SHOWERS
ARE ALSO EXPECTED TO CONTINUE DOWNWIND OF THE GREAT LAKES,
PARTICULARLY LAKES ERIE AND ONTARIO. DAILY SHOWER AND THUNDERSTORM
CHANCES ARE FORECAST FOR THE FLORIDA PENINSULA WITH COVERAGE AND
INTENSITY INCREASING ON TUESDAY ALONG THE ATLANTIC COAST. MUCH OF
THE COUNTRY WILL SEE HIGH TEMPERATURES ABOVE AVERAGE WITH
GENERALLY MILD CONDITIONS. SOME OF THE GREATEST ANOMALIES WILL BE
OVER THE MIDWEST MONDAY AS HIGHS CLIMB INTO THE 50S, AND OVER THE
NORTHEAST TUESDAY WITH HIGHS INTO THE 50S AND 60S. FRONTAL
PASSAGES WILL LEAD TO MORE TEMPERATURE FLUCTUATION ALONG THE
NORTHERN TIER OF THE COUNTRY WHILE THE SOUTHERN TIER WILL REMAIN
MORE STABLE, WITH DAILY HIGHS GENERALLY IN THE 60S AND 70S.
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