067  
FXUS01 KWBC 301933  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
232 PM EST FRI NOV 30 2018  
 
VALID 00Z SAT DEC 01 2018 - 00Z MON DEC 03 2018  
 
...SEVERE THUNDERSTORMS AND HEAVY RAINFALL ARE LIKELY ACROSS  
PORTIONS OF THE SOUTHERN PLAINS, LOWER MISSISSIPPI VALLEY AND GULF  
COAST STATES...  
   
..MAJOR WINTER STORM TO IMPACT THE GREAT PLAINS THIS WEEKEND
 
 
...UNSETTLED WEATHER WILL CONTINUE ACROSS MUCH OF THE WESTERN U.S.  
WITH LOCALLY HEAVY RAIN AND HIGH ELEVATION SNOWFALL...  
 
A VERY ACTIVE AND WET PATTERN IS ANTICIPATED THIS WEEKEND OVER A  
LARGE PORTION OF THE NATION AS A SERIES OF STORM SYSTEMS CROSSING  
THE WESTERN U.S. ADVANCE DOWNSTREAM ACROSS THE PLAINS, MIDWEST AND  
GRADUALLY TOWARD THE EASTERN SEABOARD.  
 
THE CONCERN FOR TONIGHT AND SATURDAY WILL BE SEVERE WEATHER AND  
HEAVY RAINFALL WHICH IS EXPECTED TO IMPACT AREAS OF THE SOUTHERN  
PLAINS, LOWER MISSISSIPPI VALLEY AND GULF COAST STATES AS  
DEEPENING LOW PRESSURE NEAR THE OKLAHOMA AND TEXAS PANHANDLES  
EJECTS OFF TO THE EAST OVERNIGHT AND THEN TOWARD THE MIDWEST ON  
SATURDAY. THE LOW CENTER AND SUPPORTING UPPER TROUGH ALOFT WILL  
INTERACT WITH AN INCREASINGLY MOIST AND UNSTABLE AIRMASS POOLING  
NORTH FROM THE GULF OF MEXICO AND ALONG A QUASI-STATIONARY FRONT  
DRAPED ACROSS THE OHIO VALLEY SOUTHWESTWARD TO THE LOWER  
MISSISSIPPI VALLEY. WIDESPREAD SHOWERS AND THUNDERSTORMS WILL  
DEVELOP ALONG AND SOUTH OF THIS FRONT OVERNIGHT, AND CONDITIONS  
ARE EXPECTED TO BE CONDUCIVE FOR SEVERE WEATHER AND LOCALLY HEAVY  
RAINFALL AMOUNTS. IN FACT, THE STORM PREDICTION CENTER HAS  
HIGHLIGHTED AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR THE  
ARKLATEX REGION INCLUDING ADJACENT AREAS OF THE SOUTHERN PLAINS  
AND LOWER MISSISSIPPI VALLEY FOR TONIGHT. THE HAZARDS WILL  
TORNADOES, DAMAGING WINDS AND LARGE HAIL. ON SATURDAY, THE HEAVY  
RAINFALL AND SEVERE WEATHER THREAT WILL SHIFT EAST TO INCLUDE THE  
REMAINDER OF THE CENTRAL AND EASTERN GULF COAST STATES AS A COLD  
FRONT GRADUALLY APPROACHES FROM THE WEST.  
 
FARTHER NORTH, AROUND THE NORTHWEST SIDE OF THE SAME LOW PRESSURE  
CENTER CAUSING THE HEAVY RAIN AND SEVERE WEATHER CONCERNS, WILL BE  
A MAJOR WINTER STORM WHICH IS EXPECTED TO HIT AREAS OF THE GREAT  
PLAINS ON SATURDAY INCLUDING A LARGE AREA OF THE NORTHERN AND  
CENTRAL PLAINS. HEAVY SNOW AND STRONG WINDS ARE EXPECTED ACROSS  
THESE AREAS, AND ESPECIALLY OVER SOUTHERN SOUTH DAKOTA AND  
NORTH-CENTRAL NEBRASKA WHERE SNOWFALL TOTALS OF AS MUCH AS 12 TO  
18 INCHES ARE EXPECTED. A PERIOD OF SLEET AND FREEZING RAIN IS  
EXPECTED LOCALLY AS WELL BEFORE A CHANGEOVER TO ALL SNOW OCCURS.  
THUS, THE COMBINATION OF HEAVY SNOW AND ICE WILL RESULT IN  
HAZARDOUS TRAVEL CONDITIONS. BY SUNDAY, THE SNOW WILL BEGIN TO  
ADVANCE NORTHEAST ACROSS AREAS OF THE UPPER MIDWEST AND THE UPPER  
GREAT LAKES. NUMEROUS WINTER STORM WARNINGS, WATCHES AND  
ADVISORIES ARE IN EFFECT ACROSS THESE AREAS IN ANTICIPATION OF  
THIS NEXT MAJOR WINTER STORM. SOME SNOW AND EVEN AREAS OF SLEET  
AND FREEZING RAIN WILL ALSO BE POSSIBLE ACROSS THE FAR NORTHERN  
AND INTERIOR SECTIONS OF THE NORTHEAST AS MOISTURE AHEAD OF THIS  
SYSTEM ARRIVES ON SUNDAY WITH A MARGINALLY COLD AIRMASS FOR WINTER  
WEATHER. RAIN AND SOME THUNDERSTORMS WILL BE EXPECTED FARTHER  
SOUTH ALONG THE EASTERN SEABOARD BY SUNDAY AS A COLD FRONT ARRIVES  
FROM THE WEST AND WITH MUCH WARMER TEMPERATURES IN PLACE AS WELL.  
 
ACROSS THE WESTERN U.S., A NEW STORM SYSTEM WILL ARRIVE ACROSS THE  
PACIFIC NORTHWEST WHICH WILL BRING ANOTHER ROUND OF HEAVIER  
PRECIPITATION TO ESPECIALLY SOUTHWEST OREGON AND NORTHERN  
CALIFORNIA TONIGHT AND SATURDAY. THIS WILL BRING A NEW ROUND OF  
HEAVY SNOWFALL FOR THE SIERRA-NEVADA AND ALSO PORTIONS OF THE  
CASCADES. IN FACT, ADDITIONAL SNOWFALL TOTALS OF 1 TO 2 FEET CAN  
BE EXPECTED GOING THROUGH SATURDAY. BY SUNDAY, ALL OF THIS PACIFIC  
MOISTURE AND ENERGY WILL TRAVERSE THE GREAT BASIN AND THE CENTRAL  
AND SOUTHERN ROCKIES. THE RESULT WILL BE LOCALLY HEAVY SNOWFALL  
OVER THE HIGHER TERRAIN. AREAS LIKELY TO SEE THE HEAVIEST AMOUNTS  
WILL BE THE WASATCH OF UTAH AND THE SAN JUAN MOUNTAINS OF  
SOUTHWEST COLORADO WHERE OVER 1 FOOT OF NEW SNOW IS POSSIBLE.  
 
REGARDING TEMPERATURES, THERE WILL BE NOTABLY MILDER TEMPERATURES  
GRADUALLY SHIFTING FROM THE MIDWEST TO THE EASTERN U.S. THIS  
WEEKEND, WITH TEMPERATURES LOCALLY OVER 20 DEGREES ABOVE NORMAL  
FROM THE OHIO VALLEY DOWN TO THE LOWER MISSISSIPPI VALLEY REGION.  
MEANWHILE, ALL OF THE UNSETTLED WEATHER MOVING THROUGH THE WEST  
WILL KEEP TEMPERATURES HERE MUCH COLDER AND ESPECIALLY OVER THE  
ROCKIES BY SUNDAY WHERE TEMPERATURES WILL BE AS MUCH AS 15 DEGREES  
BELOW NORMAL.  
 
ORRISON  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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