985  
FXUS21 KWNC 301934  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST NOVEMBER 30 2017  
 
SYNOPSIS: AT THE START OF THE PERIOD, LOW PRESSURE AT THE SURFACE AND MID  
LEVELS IS EXPECTED TO MOVE FROM THE INTERIOR NORTHWEST U.S. ACROSS THE NORTHERN  
ROCKIES TO THE NORTHERN PLAINS. SURFACE HIGH PRESSURE OVER THE EASTERN U.S. IS  
FORECAST TO MOVE OFF THE COAST DEC 4-5, RESULTING IN SOUTHERLY FLOW AT THE  
SURFACE DRAWING MOISTURE NORTHWARD FROM THE GULF OF MEXICO. A COLD FRONT  
ASSOCIATED WITH THE AREA OF LOW PRESSURE AT MID-LEVELS MOVING ACROSS THE NATION  
IS ANTICIPATED TO MOVE OVER THE CENTRAL, THEN EASTERN U.S. DEC 4-6, AND THEN  
OFF THE EAST COAST DEC 7. STRONG AREAS OF SURFACE LOW PRESSURE ARE PREDICTED TO  
MOVE ACROSS THE BERING SEA AND ALEUTIANS DEC 3-7. DURING WEEK-2, STRONG  
MID-LEVEL HIGH PRESSURE IS FORECAST ALONG THE WEST COAST AND OVER EASTERN  
MAINLAND ALASKA, WHILE STRONG MID-LEVEL LOW PRESSURE IS PREDICTED OVER THE  
EAST-CENTRAL AND EASTERN PARTS OF THE LOWER 48 STATES. AREAS OF ARCTIC HIGH  
PRESSURE ARE EXPECTED TO MOVE OVER THE CENTRAL U.S. TOWARDS THE END OF THE  
WEEK-2 PERIOD.  
 
HAZARDS  
 
HEAVY SNOW FOR PARTS OF THE NORTHERN ROCKIES, SUN, DEC 3.  
 
HEAVY RAIN FOR PARTS OF THE LOWER MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS,  
SOUTHEAST, MID-ATLANTIC, AND SOUTHERN APPALACHIANS, MON-WED, DEC 4-6.  
 
PERIODS OF HIGH SIGNIFICANT WAVE HEIGHTS FOR PARTS OF THE ALASKA PENINSULA,  
SOUTH COASTAL MAINLAND ALASKA, AND ALASKA PANHANDLE, MON-WED, DEC 4-6.  
 
PERIODS OF HIGH WINDS FOR PARTS OF THE ALEUTIANS, ALASKA PENINSULA, SOUTH  
COASTAL MAINLAND ALASKA, AND THE ALASKA PANHANDLE, SUN-THU, DEC 3-7.  
 
HIGH WINDS FOR PARTS OF THE NORTHWEST ARCTIC COAST OF MAINLAND ALASKA, MON-TUE,  
DEC 4-5.  
 
PERIODS OF HEAVY PRECIPITATION ACROSS PORTIONS OF THE ALASKA PENINSULA, SOUTH  
COASTAL MAINLAND ALASKA, AND THE ALASKA PANHANDLE, SUN-THU, DEC 3-7.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR MUCH OF THE CENTRAL AND  
EASTERN CONUS (WITH THE EXCEPTION OF PORTIONS OF THE NORTHEAST), FRI-THU, DEC  
8-14.  
 
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF THE LOWER  
MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS, AND CENTRAL AND SOUTHERN APPALACHIANS  
SAT-TUE, DEC 9-12.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF THE NORTHERN PLAINS  
AND UPPER MISSISSIPPI VALLEY, THU, DEC 14.  
 
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF THE NORTHERN  
PLAINS, THU DEC 14.  
 
SEVERE DROUGHT ACROSS THE LOWER MISSISSIPPI VALLEY, THE NORTHERN PLAINS,  
HAWAII, THE NORTHERN ROCKIES, THE MIDDLE MISSISSIPPI VALLEY, THE SOUTHERN  
PLAINS, AND THE SOUTHWEST.  
 
DETAILED SUMMARY  
 
FOR SUNDAY DECEMBER 03 - THURSDAY DECEMBER 07: LOW PRESSURE MOVING ACROSS THE  
NORTHWEST CONUS AND NORTHERN ROCKIES BRINGS THE LIKELIHOOD OF HEAVY SNOW  
(AMOUNTS IN EXCESS OF 6 INCHES IN 24 HOURS) FOR PARTS OF THE NORTHERN ROCKIES  
DEC 3.  
 
AS HIGH PRESSURE MOVES OFF THE EAST COAST DURING DEC 4-5, MOIST SOUTHERLY FLOW  
IS EXPECTED TO BE ESTABLISHED OVER PARTS OF THE INTERIOR SOUTHEAST CONUS. A  
COLD FRONT ASSOCIATED WITH A TROUGH MOVING ACROSS THE CENTRAL U.S. WILL ACT AS  
A FOCUSING MECHANISM FOR SHOWERS AND THUNDERSTORMS. HEAVY RAIN (AMOUNTS IN  
EXCESS OF 1 INCH IN 24 HOURS) IS ANTICIPATED FOR PARTS OF THE LOWER  
MISSISSIPPI, TENNESSEE, OHIO VALLEYS, SOUTHEAST, MID-ATLANTIC, AND SOUTHERN  
APPALACHIANS DEC 4-6. ALTHOUGH THUNDERSTORMS ARE POSSIBLE, ORGANIZED AREAS OF  
SEVERE WEATHER ARE NOT CURRENTLY ANTICIPATED. SNOW IS POSSIBLE AT THE HIGHER  
ELEVATIONS OF THE SOUTHERN APPALACHIANS, BUT MODEL UNCERTAINTY PRECLUDES THE  
SPECIFICATION OF A HEAVY SNOW HAZARD SHAPE AT THE CURRENT TIME. SNOWFALL IS  
ALSO POSSIBLE ON THE NORTHWEST PERIPHERY OF THE PRECIPITATION SHIELD AND THIS  
SITUATION WILL NEED TO BE MONITORED IN FUTURE OUTLOOKS. SOME MODELS ALSO  
INDICATE THE POSSIBILITY OF HEAVY SNOWFALL OVER PARTS OF THE SOUTHERN PLAINS  
BUT THERE ARE HUGE DIFFERENCES IN THE HANDLING OF TROUGH ENERGY OVER THE REGION  
SO A HAZARD SHAPE CAN NOT BE SPECIFIED AT THE CURRENT TIME.  
 
STRONG AREAS OF LOW PRESSURE ARE ANTICIPATED TO IMPACT THE BERING SEA,  
ALEUTIANS AND ALASKA PENINSULA DEC 3-7. PERIODS OF HIGH SIGNIFICANT WAVE  
HEIGHTS (IN EXCESS OF 20 FEET) ARE FORECAST FOR PARTS OF THE ALASKA PENINSULA,  
SOUTH COASTAL MAINLAND ALASKA, AND ALASKA PANHANDLE DEC 4-6. PERIODS OF HIGH  
WINDS (SPEEDS IN EXCESS OF 30 KNOTS) ARE PREDICTED FOR PARTS OF THE ALEUTIANS,  
ALASKA PENINSULA, SOUTH COASTAL MAINLAND ALASKA, AND THE ALASKA PANHANDLE DEC  
3-7. PERIODS OF HEAVY PRECIPITATION (RAINFALL IN EXCESS OF 2 INCHES IN 24 HOURS  
AT LOW ELEVATIONS, SNOWFALL IN EXCESS OF 8 INCHES IN 24 HOURS AT HIGHER  
ELEVATIONS) ARE FORECAST ACROSS PORTIONS OF THE ALASKA PANHANDLE AND SOUTHERN  
COASTAL MAINLAND ALASKA DEC 3-7. STRONG OFFSHORE FLOW IS FORECAST TO RESULT IN  
HIGH WINDS (SPEEDS IN EXCESS OF 40 KNOTS) ON THE NORTHWEST ARCTIC COAST OF  
ALASKA FROM POINT HOPE TO BARROW DEC 4-5.  
 
FOR FRIDAY DECEMBER 08 - THURSDAY DECEMBER 14: A STRONG MID-LEVEL RIDGE IS  
EXPECTED ALONG THE WEST COAST DURING MUCH OF THE PERIOD RESULTING IN A DRIER  
PATTERN FOR THE PACIFIC NORTHWEST. A DEEP MID-LEVEL TROUGH IS FORECAST OVER THE  
EAST-CENTRAL AND EASTERN CONUS. THIS DEEP TROUGH LEADS TO A SLIGHT RISK OF MUCH  
BELOW NORMAL TEMPERATURES FOR MUCH OF THE CENTRAL AND EASTERN CONUS (WITH THE  
EXCEPTION OF PORTIONS OF THE NORTHEAST) DEC 8-14, AND A MODERATE RISK OF MUCH  
BELOW NORMAL TEMPERATURES FOR PARTS OF THE LOWER MISSISSIPPI, OHIO AND  
TENNESSEE VALLEYS, AND CENTRAL AND SOUTHERN APPALACHIANS DEC 9-12. FREEZING  
TEMPERATURES MAY EXTEND AS FAR SOUTH AS CENTRAL FLORIDA, WHILE SUB-ZERO MINIMUM  
TEMPERATURES COULD SHIFT INTO THE MIDWEST. LATE IN WEEK-2, ARCTIC HIGH PRESSURE  
IS FORECAST TO MOVE FROM WEST-CENTRAL CANADA TO THE NORTHERN PLAINS. THUS A  
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES IS INDICATED FOR PARTS OF THE  
NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY DEC 14, WHILE A MODERATE RISK OF  
MUCH BELOW NORMAL TEMPERATURES IS FORECAST FOR PARTS OF THE NORTHERN PLAINS ON  
THE SAME DAY.  
 
A STORMY PATTERN IS LIKELY TO PERSIST FOR WESTERN AND SOUTH COASTAL MAINLAND  
ALASKA DURING MUCH OF THE WEEK-2 PERIOD.  
 
THE U.S. DROUGHT MONITOR, UPDATED ON NOV 28, SHOWS SEVERE TO EXCEPTIONAL  
(D2-D4) DROUGHT COVERS 4.88% OF THE CONTINENTAL UNITED STATES, A SLIGHT  
INCREASE OF 0.74% COVERAGE FROM THE PREVIOUS WEEK.  
 
FORECASTER: RANDY SCHECHTER  
 

 
 
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