509
FXUS01 KWBC 271911
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
210 PM EST FRI DEC 27 2024
VALID 00Z SAT DEC 28 2024 - 00Z MON DEC 30 2024
...ATMOSPHERIC RIVER TO BRING LOW ELEVATION RAIN AND HIGH
ELEVATION SNOW TO THE WEST THROUGH THE WEEKEND...
...INCREASINGLY WET PATTERN FORECAST TO DEVELOP OVER THE EASTERN
U.S. THIS WEEKEND...
...MILD AND MUCH ABOVE AVERAGE TEMPERATURES WILL PERSIST ACROSS
MOST OF THE COUNTRY...
A SLOW MOVING FRONTAL BOUNDARY WILL MOVE INTO THE PACIFIC
NORTHWEST TONIGHT AND DIRECT A PLUME OF PACIFIC MOISTURE AT THE
WEST COAST, WHICH WILL BE THE NEXT ATMOSPHERIC RIVER TO IMPACT THE
WEST. MOISTURE WILL SPREAD FROM THE COAST ACROSS THE INTERMOUNTAIN
WEST, RESULTING IN WIDESPREAD LOW ELEVATION RAIN AND HIGH
ELEVATION SNOW. HEAVY RAIN WITH INTENSE RAIN RATES COULD PRODUCE
INSTANCES OF FLOODING IN COASTAL OREGON AND NORTHERN CALIFORNIA,
AND THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL (LEVEL 2/4) FOR
THIS REGION ON SATURDAY AND SUNDAY. HEAVY MOUNTAIN SNOW COULD
CAUSE MODERATE TO MAJOR IMPACTS FOR THE HIGHER ELEVATIONS OF THE
CASCADES AND NORTHERN ROCKIES. HEAVY SNOW COMBINED WITH STRONG
WINDS COULD LEAD TO BLOWING AND DRIFTING SNOW WITH REDUCED
VISIBILITY, AND TRAVEL CONDITIONS MAY BE VERY DIFFICULT TO
IMPOSSIBLE. THE RECENT WET WEATHER PATTERN ACROSS THE NORTHWEST
AND LIKELIHOOD OF ADDITIONAL WIDESPREAD HEAVY PRECIPITATION
AMOUNTS THIS WEEKEND WILL RESULT IN INCREASING STREAM FLOWS AND
SOIL SATURATION LEVELS, LEADING TO AN INCREASING THREAT OF RIVER
FLOODING, AND ROCK AND MUDSLIDES.
PRECIPITATION IS ALSO FORECAST TO SPREAD ACROSS THE EASTERN U.S.
THIS WEEKEND AS A SERIES OF FRONTAL SYSTEMS MOVE NORTHEAST FROM
THE LOWER MISSISSIPPI VALLEY TO THE GREAT LAKES AND NORTHEAST. THE
FIRST FRONTAL SYSTEM WILL BRING RAIN TO THE LOWER MISSISSIPPI,
TENNESSEE, AND OHIO VALLEYS AND MIXED WINTRY PRECIPITATION TO THE
UPPER MIDWEST TODAY. RAIN WILL SPREAD TOWARDS THE EAST COAST AS
ANOTHER FRONTAL SYSTEM DEVELOPS OVER THE LOWER MISSISSIPPI VALLEY
ON SATURDAY, AND RAIN WILL CONTINUE THROUGH SUNDAY AS THE SECOND
SYSTEM TRACKS NORTHEAST. RAIN WILL LIKELY BE BENEFICIAL FOR MANY
AREAS THAT ARE EXPERIENCING DROUGHT CONDITIONS, ESPECIALLY IN THE
LOWER MISSISSIPPI VALLEY AND ALONG THE EAST COAST. HOWEVER,
LOCALLY HEAVY RAIN MAY ALSO RESULT IN ISOLATED INSTANCES OF FLASH
FLOODING.
WHILE STORMY WEATHER DOMINATES THE WEST AND EAST, MUCH OF THE
CENTRAL U.S. AND SOUTHWEST WILL REMAIN DRY THROUGH THE WEEKEND.
MOST OF THE NATION WILL EXPERIENCE MUCH ABOVE AVERAGE TEMPERATURES
OVER THE WEEKEND, WITH HIGH TEMPERATURES REACHING 15-25 DEGREES
ABOVE AVERAGE AND LOW TEMPERATURES REACHING 20-30 DEGREES ABOVE
AVERAGE. THIS WILL BE A CONTINUATION TO THE ABOVE AVERAGE PATTERN
FOR AREAS WEST OF THE MISSISSIPPI RIVER, BUT A REVERSAL OF THE
OVERALL BELOW AVERAGE PATTERN THAT HAS DOMINATED AREAS EAST OF THE
MISSISSIPPI DURING DECEMBER. THIS MUCH ABOVE AVERAGE PATTERN WILL
SUPPORT THE POTENTIAL FOR RECORD HIGH MORNING LOW TEMPERATURES
ACROSS THE MIDWEST, MID-ATLANTIC, AND NORTHEAST.
DOLAN
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