470  
FXUS01 KWBC 120801  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM EST THU DEC 12 2024  
 
VALID 12Z THU DEC 12 2024 - 12Z SAT DEC 14 2024  
 
...GREAT LAKES HEAVY LAKE-EFFECT SNOW EXPECTED TO CONTINUE INTO  
FRIDAY ESPECIALLY ALONG THE SNOW BELT OF THE LOWER GREAT LAKES...  
 
...A COUPLE ROUNDS OF HEAVY COASTAL RAIN AND HEAVY MOUNTAIN SNOW  
EXPECTED TO IMPACT NORTHERN CALIFORNIA INTO SIERRA NEVADA HEADING  
INTO THE WEEKEND...  
 
...SUB-ZERO TEMPERATURES EXPECTED OVER PARTS OF THE NORTHERN  
PLAINS AND UPPER MISSISSIPPI VALLEY FOR THE NEXT COUPLE OF  
MORNINGS...  
 
AS A DEEP LOW PRESSURE SYSTEM RACES FURTHER NORTHWARD INTO EASTERN  
CANADA AND A POTENT COLD FRONT EXITS NEW ENGLAND THIS MORNING, AN  
ARCTIC HIGH PRESSURE SYSTEM WILL TAKE OVER THE NORTHERN PLAINS AND  
EXPAND ACROSS THE ENTIRE EASTERN U.S. THROUGH THE NEXT COUPLE OF  
DAYS. MAINE WILL BE THE LAST TO CLEAR OUT FROM THE HEAVY RAIN  
EARLY THIS MORNING FOLLOWED BY MUCH COLDER TEMPERATURES UNDER  
BLUSTERY WESTERLY WINDS. THE RESURGENCE OF ARCTIC AIR IS  
TRIGGERING A NEW ROUND OF HEAVY LAKE-EFFECT SNOW ACROSS THE GREAT  
LAKES THROUGH TODAY AND TONIGHT BEFORE GRADUALLY TAPERING OFF ON  
FRIDAY. THE SNOW BELT OF THE LOWER GREAT LAKES CAN EXPECT A FOOT  
OR MORE OF NEW SNOW, WITH LOCATIONS DOWNWIND FROM LAKE ONTARIO  
POSSIBLY GETTING MORE THAN 2 FEET SINCE THESE LOCATIONS WILL BE  
THE LAST TO CLEAR OUT FROM THE SNOW LATE ON FRIDAY.  
 
ALONG THE WEST COAST, MOISTURE AHEAD OF THE NEXT PACIFIC CYCLONE  
IS POISED TO OVERSPREAD MUCH OF THE PACIFIC NORTHWEST AND A GOOD  
PORTION OF CALIFORNIA TODAY. THE HEAVIEST PRECIPITATION IS  
EXPECTED TO REACH NORTHERN CALIFORNIA IN FORM OF RAIN NEAR THE  
COAST AND LOWER ELEVATIONS. A QUICK ROUND OF MODERATE TO HEAVY  
SNOW WILL THEN REACH THE HIGH ELEVATIONS FARTHER INLAND AND THEN  
ALONG THE SIERRA NEVADA FOR MUCH OF TODAY. IT APPEARS THAT THIS  
LATEST AROUND OF PRECIPITATION WILL TAPER OFF TEMPORARILY TONIGHT  
BEFORE THE NEXT ROUND OF PRECIPITATION ASSOCIATED WITH THE NEXT  
PACIFIC CYCLONE ARRIVES ON FRIDAY. NORTHERN CALIFORNIA INTO  
SOUTHWESTERN OREGON CAN EXPECT HEAVY PRECIPITATION FRIDAY NIGHT  
WITH A MARGINAL RISK OF EXCESSIVE RAINFALL CONTINUING INTO  
SATURDAY MORNING BY THE END OF THE SHORT-RANGE FORECAST PERIOD.  
LESSER AMOUNTS OF PRECIPITATION ARE EXPECTED FOR THE PACIFIC  
NORTHWEST.  
 
THE ARCTIC HIGH PRESSURE SYSTEM THAT IS FORECAST TO BRING SUB-ZERO  
TEMPERATURES FOR THE NEXT COUPLE OF MORNINGS IS FORECAST TO  
STRENGTHEN AND SLIDE EAST INTO NEW ENGLAND BY SATURDAY MORNING.  
THIS WILL ALLOW SOUTHERLY FLOW TO INCREASE ACROSS THE SOUTHERN  
PLAINS ALONG WITH MOISTURE RETURNING FROM THE GULF OF MEXICO BY  
FRIDAY NIGHT. MEANWHILE, RESIDUAL ENERGY ASSOCIATED WITH THE  
FIRST PACIFIC SYSTEM IS FORECAST TO EXIT THE SOUTHERN ROCKIES AND  
INDUCE THE FORMATION OF A LOW PRESSURE SYSTEM OVER THE CENTRAL  
PLAINS BY FRIDAY NIGHT. SOME THUNDERSTORMS ALONG WITH HEAVY RAIN  
COULD QUICKLY DEVELOP AND MOVE ACROSS THE CENTRAL PLAINS EARLY ON  
SATURDAY AHEAD OF THE NEW LOW PRESSURE SYSTEM. COLDER AIR COULD  
SUPPORT AREAS OF MIXED RAIN AND SNOW FARTHER NORTH ACROSS THE  
NORTH-CENTRAL PLAINS INTO THE UPPER MIDWEST IN ADVANCE OF THE LOW  
PRESSURE CENTER. IN THE SHORT-TERM THOUGH, DRY, BREEZY AND  
RELATIVELY MILD CONDITIONS WILL SUPPORT ELEVATED FIRE DANGER  
ACROSS THE SOUTHERN HIGH PLAINS FOR TODAY.  
 
KONG  
 
GRAPHICS AVAILABLE AT  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  
 
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