575  
FXUS01 KWBC 220528  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
1227 AM EST SUN DEC 22 2024  
 
VALID 12Z SUN DEC 22 2024 - 12Z TUE DEC 24 2024  
 
...PERIODS OF MODERATE TO HEAVY RAINFALL FOR THE PACIFIC NORTHWEST  
AND NORTHERN CALIFORNIA AS SYSTEMS MOVE IN FROM THE NORTH  
PACIFIC...  
 
...RECORD WARMTH POSSIBLE ACROSS PARTS OF THE SOUTHWEST ON  
SUNDAY...  
 
...MORE WINTER WEATHER FROM THE NORTHERN PLAINS THROUGH THE GREAT  
LAKES AND THE NORTHEAST FROM SUNDAY INTO TUESDAY MORNING...  
 
THE GENERAL FLOW PATTERN BECOMES MORE ZONAL WITH TIME, WITH  
SYSTEMS OF PACIFIC ORIGIN MOVING EASTWARD AND REFORMING DOWNSTREAM  
ACROSS THE PLAINS/MIDWEST. THE CONSEQUENCE OF THIS PATTERN WILL BE  
RAINFALL/ELEVATION SNOWS NEAR THE PACIFIC NORTHWEST & NORTHERN  
CALIFORNIA, DECREASING WARMTH ACROSS THE WEST, AND BY MONDAY  
DECREASING COLD ACROSS PORTIONS OF THE EAST. STARTING OUT WEST,  
WEAKENING FRONTS MOVE EASTWARD OUT OF THE PACIFIC INTO THE GREAT  
BASIN, PUSHING BATCHES OF RAINFALL INTO AND THROUGH THE PACIFIC  
NORTHWEST, NORTHERN INTERMOUNTAIN WEST, AND NORTHERN CALIFORNIA,  
WITH SNOWFALL EXPECTED AT HIGHER ELEVATIONS THROUGH TUESDAY  
MORNING. THE HEAVIEST PRECIPITATION IS EXPECTED IN AND NEAR  
NORTHERN CALIFORNIA MONDAY NIGHT AND TUESDAY, WHICH CARRIES SOME  
RISK OF EXCESSIVE RAINFALL/FLASH FLOODING, PARTICULARLY IN BURN  
SCARS. SOME PERIODS OF HIGH WINDS ARE EXPECTED ON SUNDAY -- WIND  
ADVISORIES ARE IN EFFECT FOR AREAS OF NORTHERN CALIFORNIA AND  
SOUTHERN OREGON. ACROSS THE SOUTHWEST, HIGH TEMPERATURES SHOULD  
RISE 60S TO 70S ON SUNDAY, THREATENING DAILY RECORD HIGH  
TEMPERATURES IN AND NEAR SOUTHERN ARIZONA AND SOUTHERN CALIFORNIA.  
AS ONE OF THE PACIFIC DISTURBANCES ALOFT MOVES EAST OF THE  
ROCKIES, A LOW PRESSURE SYSTEM DEVELOPS ACROSS THE UPPER MIDWEST  
AND GREAT LAKES SUNDAY INTO EARLY MONDAY, WHICH IS EXPECTED TO  
BRING FREEZING RAIN TO PORTIONS OF NORTHEAST MONTANA AND NORTHWEST  
NORTH DAKOTA -- WINTER WEATHER ADVISORIES ARE IN EFFECT -- THEN  
SNOWFALL WHICH INCREASES IN COVERAGE AND INTENSITY WITH TIME FROM  
NORTH DAKOTA EASTWARD THROUGH MICHIGAN INTO THE NORTHEAST. THIS  
SYSTEM SHOULD WEAKEN AS IT MOVES THROUGH THE NORTHEAST.  
 
A SEASONABLY STRONG AND COLD HIGH PRESSURE SYSTEM MIGRATES THROUGH  
THE EAST INTO THE WESTERN ATLANTIC ON SUNDAY AND MONDAY,  
CONTINUING THE COLD IN THE EASTERN UNITED STATES. COLD WEATHER  
ADVISORIES ARE IN EFFECT ACROSS PORTIONS OF EASTERN UPSTATE NEW  
YORK AND NORTHEAST PENNSYLVANIA, WHILE FREEZE WARNINGS AND FROST  
ADVISORIES ARE OUT FOR PORTIONS OF SOUTHEAST GEORGIA AND NORTH  
FLORIDA FOR SUNDAY MORNING. AS THE FLOW OVER THE GREAT LAKES  
BECOMES MORE ANTICYCLONIC WITH TIME, LAKE EFFECT SNOWS SHOULD  
CONTINUE TO FADE ON SUNDAY. FOR SOME AREAS OF THE EAST, SUNDAY  
SHOULD BE THE COLDEST DAY THUS FAR THIS WINTER. ONCE THE HIGH  
MOVES OFFSHORE ON MONDAY, TEMPERATURES SHOULD BEGIN TO MODERATE  
CLOSER TO LATE DECEMBER AVERAGES.  
 
ROTH  
 
GRAPHICS AVAILABLE AT  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  
 
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