433  
FXUS01 KWBC 292000  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
256 PM EST THU NOV 29 2018  
 
VALID 00Z FRI NOV 30 2018 - 00Z SUN DEC 02 2018  
 
...HEAVY PRECIPITATION IS EXPECTED OVER LARGE PORTIONS OF THE WEST  
GOING INTO THE WEEKEND INCLUDING VERY HEAVY SNOW FOR THE  
SIERRA-NEVADA AND THE ROCKIES...  
 
...A NEW WINTER STORM WILL BEGIN TO IMPACT PORTIONS OF THE  
NORTHERN PLAINS AND UPPER MIDWEST BY THIS WEEKEND...  
 
...SEVERE WEATHER AND HEAVY RAINFALL ARE LIKELY ACROSS AREAS OF  
THE SOUTHERN PLAINS, LOWER MISSISSIPPI VALLEY AND GULF COAST  
STATES...  
 
A WET, ACTIVE PATTERN IS EXPECTED TO CONTINUE THROUGH THE WEEKEND  
FOR THE WESTERN U.S., PARTICULARLY IN CALIFORNIA AND ALSO AREAS  
DOWNSTREAM ACROSS THE ROCKIES. A VIGOROUS UPPER LOW AND ASSOCIATED  
FRONTAL SYSTEM IS CURRENTLY BRINGING HEAVY RAINFALL WITH EMBEDDED  
THUNDERSTORMS ACROSS CALIFORNIA, ALONG WITH HEAVY SNOW OVER THE  
HIGHER TERRAIN OF THE SIERRA-NEVADA. THIS WILL CONTINUE THROUGH  
TONIGHT WITH LIGHTER PRECIPITATION ACROSS THE PACIFIC NORTHWEST.  
HOWEVER, AS THE AFOREMENTIONED UPPER LOW AND FRONT MOVE FARTHER  
INLAND GOING THROUGH FRIDAY, PRECIPITATION WILL INCREASE ACROSS  
THE GREAT BASIN AND ALSO THE CENTRAL ROCKIES WHILE STILL  
PERSISTING ACROSS CENTRAL AND SOUTHERN CALIFORNIA. AS THIS SYSTEM  
EXITS OUT TOWARD THE SOUTHERN PLAINS BY FRIDAY NIGHT, THERE WILL  
ALREADY BE A NEW STORM SYSTEM ARRIVING ACROSS THE PACIFIC  
NORTHWEST WHICH WILL BRING ANOTHER ROUND OF HEAVIER PRECIPITATION  
TO ESPECIALLY SOUTHWEST OREGON AND NORTHERN CALIFORNIA FRIDAY  
NIGHT AND SATURDAY. A NEW ROUND OF HEAVY SNOWFALL IS EXPECTED OVER  
THE SIERRA-NEVADA AND ALSO PORTIONS OF THE CASCADES. IN FACT,  
MULTI-DAY SNOWFALL TOTALS THROUGH SATURDAY ARE EXPECTED TO BE IN  
EXCESS OF 2 FEET LOCALLY. BETWEEN THE TWO SYSTEMS IMPACTING THE  
WEST, THERE ARE NUMEROUS WINTER STORM WARNINGS AND ADVISORIES IN  
EFFECT TO ADDRESS THE WINTER WEATHER HAZARDS. ALSO, BECAUSE OF THE  
HEAVY RAINFALL, THERE ARE CONCERNS FOR SOME FLASH FLOODING IN  
CALIFORNIA AND ESPECIALLY IN AND AROUND THE BURN SCAR AREAS. IN  
FACT, THE WEATHER PREDICTION CENTER HAS HIGHLIGHTED A SLIGHT RISK  
OF EXCESSIVE RAINFALL FOR THESE AREAS.  
 
BY LATE FRIDAY, A QUASI-STATIONARY FRONT WILL BE DRAPED ACROSS THE  
OHIO VALLEY SOUTHWESTWARD TO THE LOWER MISSISSIPPI VALLEY. THIS  
WILL BECOME AN INCREASING FOCUS FOR SHOWERS AND THUNDERSTORMS AND  
ESPECIALLY AS LOW PRESSURE DEEPENS IN THE LEE OF THE SOUTHERN  
ROCKIES BY FRIDAY EVENING. THE AFOREMENTIONED FRONT WILL BEGIN TO  
LIFT NORTH AS A WARM FRONT FRIDAY NIGHT AND SATURDAY. DEEP  
SOUTHERLY FLOW AHEAD OF A COLD FRONT ADVANCING EAST ACROSS TEXAS  
WILL SEND COPIOUS AMOUNTS OF MOISTURE FROM THE GULF OF MEXICO  
NORTHWARD ACROSS THE LOWER MISSISSIPPI VALLEY. THIS COUPLED WITH A  
DESTABILIZING AIRMASS WILL SET THE STAGE FOR HEAVY RAIN AND SEVERE  
WEATHER ACROSS PORTIONS OF THE SOUTHERN PLAINS AND LOWER  
MISSISSIPPI VALLEY LATE FRIDAY AND INTO EARLY SATURDAY. IN FACT,  
THE STORM PREDICTION CENTER HAS HIGHLIGHTED AN ENHANCED RISK OF  
SEVERE THUNDERSTORMS FOR THESE AREAS. ON SATURDAY, THE HEAVY  
RAINFALL AND SEVERE WEATHER THREAT WILL SHIFT EAST TO INCLUDE THE  
OHIO VALLEY, TENNESSEE VALLEY AND THE CENTRAL AND EASTERN GULF  
COAST STATES. FARTHER NORTH, HEAVY SNOW IS EXPECTED TO DEVELOP  
ACROSS THE NORTHERN PLAINS ALONG WITH NORTH-CENTRAL NEBRASKA BY  
FRIDAY NIGHT. ON SATURDAY, HEAVY SNOW WILL IMPACT THE SOUTH DAKOTA  
AND NEBRASKA BORDER REGION ALONG WITH ADJACENT AREAS OF THE UPPER  
MIDWEST. WINTER STORM WATCHES ARE ALREADY IN EFFECT IN  
ANTICIPATION OF THIS NEXT WINTER STORM.  
 
ABOVE AVERAGE TEMPERATURES ARE EXPECTED TO GRADUALLY SHIFT FROM  
THE PLAINS AND MIDWEST TO THE EASTERN U.S. THIS WEEKEND, WITH  
TEMPERATURES LOCALLY OVER 20 DEGREES ABOVE NORMAL OVER THE OHIO  
VALLEY AND THE LOWER TO MIDDLE MISSISSIPPI VALLEY REGION.  
MEANWHILE, ALL OF THE UNSETTLED WEATHER MOVING THROUGH THE WEST  
WILL RESULT IN TEMPERATURES BEING BELOW NORMAL AND ESPECIALLY OVER  
THE ROCKIES BY SUNDAY.  
 
ORRISON  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page