781
FXUS01 KWBC 010747
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
247 AM EST FRI DEC 01 2023
VALID 12Z FRI DEC 01 2023 - 12Z SUN DEC 03 2023
...MULTI-DAY WINTER STORM WILL IMPACT TRAVEL IN THE NORTHWEST WITH
SIGNIFICANT MOUNTAIN SNOW AND HEAVY RAIN...
...UNSETTLED WEATHER FORECAST ACROSS THE EASTERN THIRD OF THE
COUNTRY WITH HEAVY RAIN POTENTIAL ALONG THE GULF COAST AND
SOUTHEAST, WHILE WINTRY WEATHER IS EXPECTED FROM PARTS OF THE
MIDWEST AND GREAT LAKES TO NORTHERN NEW ENGLAND...
METEOROLOGICAL WINTER IS OFF TO A FAST START ACROSS MUCH OF THE
NORTHWEST, GREAT BASIN, AND ROCKIES AS PLENTIFUL MOISTURE STREAMS
INLAND FROM THE PACIFIC OCEAN OVER AT LEAST THE NEXT FEW DAYS. THE
SPECIFIC REGION SEEING THE MOST IMPACTS FROM HEAVY MOUNTAIN SNOW
AND HEAVY RAIN WILL BE THE PACIFIC NORTHWEST, WHERE A STRONG
ATMOSPHERIC RIVER IS EXPECTED TO WALLOP THE REGION ON SUNDAY AFTER
CONTINUOUS INSTANCES OF MODERATE PRECIPITATION TODAY AND SATURDAY.
TOTAL RAINFALL AMOUNTS THROUGH THIS WEEKEND ARE EXPECTED TO
APPROACH 5 TO 10 INCHES ALONG THE COASTAL RANGES OF WESTERN
WASHINGTON AND OREGON, WITH SEVERAL INCHES OF RAIN ALSO EXPECTED
FOR PLACES SUCH AS PORTLAND, OR AND SEATTLE, WA. HEAVY SNOW LIKELY
ADDING UP TO AT LEAST A FEW FEET IS EXPECTED ACROSS THE CASCADES,
INCLUDING MANY MOUNTAIN PASSES. TRAVEL WILL BE DIFFICULT TO
HAZARDOUS DUE TO BOTH HEAVY SNOW AND BLOWING SNOW. SNOW LEVELS ARE
EXPECTED TO INCREASE BY SATURDAY NIGHT AND THROUGHOUT THE DAY ON
SUNDAY, LEADING TO HEAVY RAIN ON TOP OF RECENT SNOWFALL THROUGHOUT
THE CASCADES. THIS COMBINATION OF HEAVY RAIN AND SNOWMELT ON
SUNDAY WILL LIKELY PRODUCE MINOR TO MODERATE RIVER FLOODING.
HEAVY SNOW POTENTIAL WILL ALSO EXTEND INTO THE MOUNTAINOUS TERRAIN
OF THE GREAT BASIN AND ROCKIES AS LEFTOVER MOISTURE TRANSPORT
CONTINUES TO SLIDE EASTWARD FROM THE PACIFIC. HEAVY SNOW IS LIKELY
TO REACH INTO SEVERAL MOUNTAIN RANGES FROM IDAHO AND MONTANA TO
COLORADO. THE HIGHEST PEAKS ARE FORECAST SEE AS MUCH AS 1 TO 3
FEET OF SNOW. WINTER STORM WARNINGS AND WINTER WEATHER ADVISORIES
HAVE BEEN ISSUED FOR AREAS MOST LIKELY TO SEE IMPACTFUL AND/OR
HAZARDOUS SNOWFALL.
AN INCREASING SOUTHWESTERLY JET STREAM OVER THE EASTERN U.S. WILL
ALLOW FOR UNSETTLED AND MILD WEATHER TO OVERSPREAD THE REGION
DURING THE FIRST WEEKEND OF DECEMBER. AN INITIAL SYSTEM IS
FORECAST TO PROGRESS FROM THE MIDWEST TO THE GREAT LAKES BY
SATURDAY AS ANOTHER DEVELOPING SYSTEM RIGHT ON ITS HEELS ENTERS
THE GREAT LAKES ON SUNDAY. OVERALL, LIGHT RAIN IS EXPECTED ACROSS
THE OHIO VALLEY, APPALACHIANS, NORTHEAST, AND MID-ATLANTIC.
HOWEVER, ELEVATED ATMOSPHERIC MOISTURE CONTENT AND INSTABILITY MAY
LEAD TO LOCALLY HEAVY RAINFALL AND THUNDERSTORMS ALONG THE GULF
COAST TODAY. THIS THREAT OF HEAVY RAINFALL THEN PUSHES FARTHER
NORTH INTO THE SOUTHEAST ON SATURDAY AHEAD OF A CENTRAL U.S. UPPER
TROUGH. FARTHER NORTH, WINTRY WEATHER IS EXPECTED ON THE NORTHERN
PERIPHERY OF THE PRECIPITATION SHIELD AS COLD AIR REMAINS IN PLACE
DUE TO A STRETCHED OUT HIGH PRESSURE SYSTEM EXTENDING INTO
SOUTHEAST CANADA. MOSTLY LIGHT AND LOCALIZED SNOWFALL IS EXPECTED
FROM PARTS OF EASTERN IOWA TO THE LOWER PENINSULA OF MICHIGAN
THROUGH TONIGHT. HEAVIER SNOW IS POSSIBLE ACROSS NORTHERN NEW
ENGLAND ON MONDAY, WHERE MODEST PROBABILITIES (40-60%) FOR GREATER
THAN 4 INCHES OF SNOW EXIST BETWEEN NORTHERN NEW HAMPSHIRE AND
NORTHERN MAINE.
ELSEWHERE, MOSTLY DRY CONDITIONS ARE EXPECTED ACROSS THE CENTRAL
AND SOUTHWESTERN UNITED STATES. BELOW AVERAGE TEMPERATURES ARE
ALSO ANTICIPATED TO BE CONFINED TO THE CENTRAL PLAINS AND WEST
THROUGH THE BEGINNING OF THE WEEKEND, WITH ABOVE AVERAGE
TEMPERATURES THROUGHOUT THE REMAINDER OF THE CONUS.
SNELL
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