829  
FXUS01 KWBC 172021  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
320 PM EST SUN DEC 17 2023  
 
VALID 00Z MON DEC 18 2023 - 00Z WED DEC 20 2023  
 
...AN INTENSE LOW PRESSURE SYSTEM WILL BRING WIND-SWEPT HEAVY RAIN  
UP THE EASTERN SEABOARD WITH STRONG THUNDERSTORMS NEAR THE COAST  
THROUGH MONDAY...  
 
...COLDER AIR BEHIND THE STORM WILL TRIGGER LAKE-EFFECT SNOW FROM  
WEST TO EAST ACROSS THE GREAT LAKES TOWARD THE APPALACHIANS AND  
UPSTATE NEW YORK INTO TUESDAY...  
 
...A COUPLE OF SLOW-MOVING OCEANIC STORMS IN THE PACIFIC WILL  
SPREAD UNSETTLED WEATHER INTO THE WEST COAST STATES THROUGH THE  
NEXT FEW DAYS...  
 
THE CENTER OF AN INTENSE LOW PRESSURE SYSTEM MOVED ACROSS NORTHERN  
FLORIDA WHERE NEW ALL-TIME LOWEST SEA-LEVEL PRESSURE VALUES FOR  
DECEMBER MIGHT HAVE BEEN ESTABLISHED EARLY THIS MORNING (PENDING  
VERIFICATION). THIS INTENSE STORM IS NOW TRACKING JUST OFF THE  
COASTLINE OF THE SOUTHEASTERN U.S. THIS SUNDAY AFTERNOON WHILE  
CONTINUES TO DEEPEN RAPIDLY. A SWATH OF MODERATE TO HEAVY RAIN  
AHEAD OF THE STORM CENTER WILL CONTINUE TO STREAM NORTHWARD UP THE  
MID-ATLANTIC STATES THROUGH TONIGHT, REACHING INTO NEW ENGLAND BY  
MONDAY MORNING. THE WARM AND MOIST AIR SURGING NORTHWARD FROM THE  
ATLANTIC WILL SHARPEN A FRONT NEAR THE COAST AHEAD OF THE ARRIVAL  
OF THE STORM CENTER. THIS FRONT WILL HELP FOCUS THE MOST INTENSE  
RAINFALL TO IMPACT AREAS JUST TO THE WEST, WHILE THE STRONGEST  
ONSHORE WINDS FROM THE EAST WILL IMPACT AREAS NEAR AND JUST INLAND  
FROM THE MID-ATLANTIC COAST THROUGH TONIGHT. THUNDERSTORMS WITH  
BRIEF INTENSE RAINFALL ALONG WITH SQUALLS CAN BE EXPECTED TO  
IMPACT THE COASTAL PLAINS AS WELL. BY MONDAY AFTERNOON, A  
DOUBLE-BARREL LOW PRESSURE SYSTEM IS FORECAST TO TRACK MORE  
QUICKLY NORTHWARD INTO NEW ENGLAND. THE RAIN ACROSS THE  
MID-ATLANTIC STATES WILL TAPER OFF FROM WEST TO EAST ON MONDAY  
BEHIND THE STORM CENTER AS WIND-SWEPT RAIN, HEAVY AT TIMES,  
OVERSPREADS THE ENTIRE NORTHEAST DURING THE DAY ON MONDAY.  
MEANWHILE, COLDER AIR FROM CENTRAL CANADA WILL BE PULLED  
SOUTHEASTWARD ACROSS THE GREAT LAKES ON MONDAY BEHIND THE BIG  
STORM, TRIGGERING LAKE-ENHANCED SNOW FROM WEST TO EAST ACROSS THE  
GREAT LAKES AND TOWARD THE APPALACHIANS BY LATER ON MONDAY. EVEN  
THOUGH THE BIG STORM WILL BEGIN TO DEPART THE NORTHEAST MONDAY  
EVENING, THE HUGE CIRCULATION OF THE STORM WILL OVERSPREAD THE  
ENTIRE EASTERN U.S. WITH VERY BLUSTERY CONDITIONS. SNOW SHOWERS  
AND LINGERING LAKE-EFFECT SNOW DOWNWIND FROM THE LOWER GREAT LAKES  
ARE EXPECTED TO GRADUALLY WIND DOWN AS THE DAY PROGRESSES ON  
TUESDAY, TAPERING OFF TO FLURRIES BY TUESDAY EVENING.  
 
MEANWHILE, PRECIPITATION AHEAD OF A LARGE AND SLOW-MOVING OCEANIC  
STORM IN THE PACIFIC HAS ALREADY REACHED CALIFORNIA ON SUNDAY.  
THIS SYSTEM WILL CONTINUE TO SPREAD UNSETTLED WEATHER UP THE WEST  
COAST THROUGH TUESDAY AS ANOTHER OCEANIC STORM APPROACHES IN ITS  
WAKE LATER ON TUESDAY. MOSTLY RAIN IS EXPECTED WITH THIS SYSTEM.  
IT APPEARS THAT THE HIGHER TERRAIN OF NORTHERN CALIFORNIA WILL  
RECEIVE THE HIGHEST PRECIPITATION TOTALS OF MORE THAN TWO INCHES  
OVER THE NEXT COUPLE OF DAYS. THE REMINDER OF THE WESTERN AND  
CENTRAL U.S. WILL REMAIN DRY THROUGH TUESDAY UNDER A STABLE AND  
EXPANSIVE HIGH PRESSURE SYSTEM.  
 
THE ENTIRE COUNTRY WILL REMAIN MILDER THAN NORMAL FOR THIS TIME OF  
YEAR BEFORE THE SURGE OF COLDER AIR FROM CANADA BRINGS BELOW  
NORMAL TEMPERATURES INTO THE OHIO VALLEY AND FLORIDA PENINSULA ON  
MONDAY. IN FACT, RECORD HIGH TEMPERATURES ARE EXPECTED ACROSS NEW  
ENGLAND ON MONDAY AS WARM AND MOIST AIR FROM THE ATLANTIC SURGES  
INTO THE REGION AMID WIND-SWEPT HEAVY RAIN IN THE HEIGHT OF THE  
BIG EASTERN STORM. COLDER THAN NORMAL TEMPERATURES WILL THEN  
OVERSPREAD THE SOUTHERN AND SOUTHEASTERN QUADRANT OF THE COUNTRY  
INCLUDING FLORIDA ON TUESDAY.  
 
KONG  
 
GRAPHICS AVAILABLE AT  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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