224
FXUS01 KWBC 312001
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 PM EST FRI JAN 31 2025
VALID 00Z SAT FEB 01 2025 - 00Z MON FEB 03 2025
...STRONG ATMOSPHERIC RIVER TO TAKE AIM AT NORTH-CENTRAL
CALIFORNIA WITH HEAVY RAIN AND POSSIBLE FLOODING OVER THE NEXT
COUPLE OF DAYS...
...ACTIVE PATTERN FOR THE NORTHWESTERN U.S. WITH HEAVY SNOW FROM
THE CASCADES TO THE NORTHERN ROCKIES...
...ABOVE AVERAGE TEMPERATURES FOR MUCH OF THE NATION THIS
WEEKEND...
THE UPPER LEVEL PATTERN WILL TRANSITION TO A ZONAL FLOW REGIME
THIS WEEKEND WITH THE JET STREAM ALIGNING FROM WEST TO EAST. THIS
PATTERN WILL PRODUCE FOCUS MOST OF THE ACTIVE WEATHER OVER THE
WESTERN U.S., LARGELY IN THE FORM OF AN ATMOSPHERIC RIVER WHICH IS
EXPECTED TO BRING INCREASING INTENSITY OF PRECIPITATION TO CENTRAL
CALIFORNIA STARTING ON SATURDAY. WHILE LIGHT RAIN/MOUNTAIN SNOW
WAS ONGOING FRIDAY AFTERNOON FROM CENTRAL CALIFORNIA TO THE
PACIFIC NORTHWEST AND NORTHERN ROCKIES, LOW LEVEL WINDS WILL
STRENGTHEN ON SATURDAY FROM THE SAN FRANCISCO BAY REGION TO
LOCATIONS JUST NORTHWARD, WITH A PLUME OF ANOMALOUS MOISTURE
EXTENDING INLAND INTO THE GREAT BASIN. THE PLUME OF MOISTURE WILL
VARY IN LATITUDE OVER THE NEXT COUPLE OF DAYS BUT REMAIN FOCUSED
OVER PORTIONS OF CENTRAL TO NORTHERN CALIFORNIA, SANDWICHED
BETWEEN LOW PRESSURE ALONG THE COAST OF BRITISH COLUMBIA AND HIGH
PRESSURE TO THE WEST OF SOUTHERN CALIFORNIA. SNOW LEVELS WILL BE
RELATIVELY HIGH WITHIN THE CORE OF THE ATMOSPHERIC RIVER WHICH
WILL KEEP HEAVY SNOW CONFINED TO ELEVATIONS ABOVE 7000 FEET IN THE
SIERRA NEVADA. THE REMAINDER OF THE PRECIPITATION WILL FALL AS
RAIN WITH THE COASTAL RANGES, JUST NORTH OF SAN FRANCISCO BAY INTO
THE SIERRA NEVADA, LIKELY PICKING UP THE HIGHEST RAINFALL TOTALS
OVER THE WEEKEND. THROUGH SUNDAY, 2 TO 4 INCHES OF RAIN IS
EXPECTED FOR THE COASTAL RANGES WITH 3 TO 7 INCHES FOR THE SIERRA
NEVADA (LOCALLY HIGHER). RAIN IS LIKELY TO CONTINUE THROUGH MONDAY
AS WELL. WHILE RAINFALL IS NEEDED FOR MANY OF THESE AREAS, IT MAY
BE TOO MUCH AT ONCE, RESULTING IN FLOODING CONCERNS AND POTENTIAL
FOR DEBRIS FLOWS WITHIN AREAS OF SENSITIVE TERRAIN AND AREA BURN
SCARS. HEAVY SNOW WITH 1 TO 2 FEET IS EXPECTED FOR THE HIGHER
ELEVATIONS OF THE NORTHERN CASCADES INTO CENTRAL IDAHO, FAR
NORTHERN UTAH AND NORTHWESTERN WYOMING. BELOW AVERAGE TEMPERATURES
WILL FILTER INTO THE PACIFIC NORTHWEST THIS WEEKEND, PERHAPS
ALLOWING FOR SNOW INTO THE CITIES OF SEATTLE AND PORTLAND, THOUGH
ANY ACCUMULATIONS ARE EXPECTED TO BE MINOR (IF ANY).
ELSEWHERE ACROSS THE LOWER 48, TEMPERATURES WILL BE ABOVE AVERAGE
FROM THE SOUTHERN GREAT BASIN INTO THE GREAT PLAINS, MIDWEST, GULF
COAST AND SOUTHEAST. AFTER THE DEPARTURE OF A COLD FRONT IN THE
EAST TONIGHT, DRIER WEATHER IS EXPECTED FOR THE WEEKEND. THE
EXCEPTION WILL BE FROM THE GREAT LAKES TO THE NORTHEAST WHERE A
QUICK MOVING DISTURBANCE WILL BRING LIGHT SNOW TO THE REGION ALONG
WITH COLDER THAN AVERAGE TEMPERATURES, ESPECIALLY ACROSS NORTHERN
NEW ENGLAND WHERE HIGH TEMPERATURES ARE FORECAST TO BE 10-20
DEGREES BELOW AVERAGE ON SATURDAY, WITH SOME MODEST WARMING ON
SUNDAY.
OTTO
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