319  
FXUS21 KWNC 011955  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST DECEMBER 01 2017  
 
SYNOPSIS: SURFACE HIGH PRESSURE OVER THE EASTERN U.S. IS FORECAST TO MOVE OFF  
THE EAST COAST DEC 4-5, RESULTING IN SOUTHERLY FLOW AT THE SURFACE DRAWING  
MOISTURE NORTHWARD FROM THE GULF OF MEXICO. AT THE SAME TIME, SURFACE LOW  
PRESSURE OVER THE CENTRAL U.S. IS EXPECTED TO DEEPEN AND MOVE NORTHEASTWARD  
INTO EASTERN CANADA. ITS TRAILING COLD FRONT IS ANTICIPATED TO MOVE FROM THE  
WEST-CENTRAL U.S. ON DEC 4, TO THE EAST-CENTRAL U.S. ON DEC 5, AND THEN OFF THE  
EAST COAST LATE ON DEC 6. STRONG AREAS OF SURFACE LOW PRESSURE ARE PREDICTED TO  
MOVE ACROSS THE BERING SEA AND ALEUTIANS DEC 4-8. 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.  
 
HAZARDS  
 
HEAVY RAIN FOR PARTS OF THE NORTHERN GREAT LAKES, MON, DEC 4.  
 
HEAVY RAIN FOR PARTS OF THE LOWER MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS,  
SOUTHEAST, AND SOUTHERN APPALACHIANS, MON-TUE, DEC 4-5.  
 
HEAVY RAIN FOR PARTS OF THE MID-ATLANTIC AND NORTHEAST, TUE, DEC 5.  
 
HEAVY PRECIPITATION FOR PARTS OF SOUTHEASTERN MAINLAND ALASKA AND THE ALASKA  
PANHANDLE, TUE-WED, DEC 5-6.  
 
HIGH SIGNIFICANT WAVE HEIGHTS FOR PARTS OF THE ALASKA PENINSULA AND SOUTH  
COASTAL MAINLAND ALASKA, MON, DEC 4.  
 
PERIODS OF HIGH WINDS FOR PARTS OF THE ALEUTIANS, ALASKA PENINSULA, SOUTH  
COASTAL MAINLAND ALASKA, AND THE ALASKA PANHANDLE, MON-FRI, DEC 4-8.  
 
HIGH WINDS FOR PARTS OF THE NORTHWEST ARCTIC COAST OF MAINLAND ALASKA, MON-TUE,  
DEC 4-5.  
 
PERIODS OF HEAVY LAKE EFFECT SNOW FOR PARTS OF THE GREAT LAKES, SAT-MON, DEC  
9-11.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR MUCH OF THE EAST-CENTRAL AND  
EASTERN CONUS, SAT-FRI, DEC 9-15.  
 
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF THE GREAT LAKES,  
CENTRAL APPALACHIANS, AND MID-ATLANTIC, MON-THU, DEC 11-14.  
 
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 MONDAY DECEMBER 04 - FRIDAY DECEMBER 08: AS HIGH PRESSURE MOVES OFF THE  
EAST COAST DURING DEC 4-5, MOIST SOUTHERLY FLOW IS EXPECTED TO BE ESTABLISHED  
OVER PARTS OF THE EASTERN CONUS. A COLD FRONT ASSOCIATED WITH DEEP LOW PRESSURE  
MOVING FROM THE CENTRAL CONUS INTO EASTERN CANADA WILL ACT AS A FOCUSING  
MECHANISM FOR SHOWERS AND THUNDERSTORMS. SEVERE WEATHER IS POSSIBLE AHEAD OF  
THE COLD FRONT, BUT CONFIDENCE IS NOT YET HIGH ENOUGH TO INDICATE A SEVERE  
WEATHER HAZARD SHAPE. HEAVY RAIN (AMOUNTS IN EXCESS OF 1 INCH IN 24 HOURS) IS  
ANTICIPATED FOR PARTS OF THE NORTHERN GREAT LAKES DEC 4, PARTS OF THE LOWER  
MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS, SOUTHEAST, AND SOUTHERN APPALACHIANS  
DEC 4-5, AND PARTS OF THE MID-ATLANTIC AND NORTHEAST DEC 5. SNOWFALL IS  
POSSIBLE OVER PARTS OF THE WESTERN GREAT LAKES DEC 4, AND INTERIOR NEW ENGLAND  
DEC 6, BUT MODEL UNCERTAINTY PRECLUDES THE SPECIFICATION OF HAZARD SHAPES AT  
THE CURRENT TIME.  
 
STRONG AREAS OF LOW PRESSURE ARE ANTICIPATED TO IMPACT THE BERING SEA,  
ALEUTIANS AND ALASKA PENINSULA DEC 4-7. HIGH SIGNIFICANT WAVE HEIGHTS (IN  
EXCESS OF 20 FEET) ARE FORECAST FOR PARTS OF THE ALASKA PENINSULA AND SOUTH  
COASTAL MAINLAND ALASKA DEC 4. 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 4-8. 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) IS FORECAST ACROSS  
PORTIONS OF THE ALASKA PANHANDLE AND SOUTHEASTERN MAINLAND ALASKA DEC 5-6.  
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 SATURDAY DECEMBER 09 - FRIDAY DECEMBER 15: 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 PATTERN IS FAVORABLE FOR LAKE EFFECT SNOW  
SO PERIODS OF HEAVY SNOW ARE INDICATED DOWNWIND OF THE GREAT LAKES DEC 9-11. IN  
ADDITION, THE DEEP TROUGH LEADS TO A SLIGHT RISK OF MUCH BELOW NORMAL  
TEMPERATURES FOR MUCH OF THE EAST-CENTRAL AND EASTERN CONUS DEC 9-15, AND A  
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF THE GREAT LAKES,  
CENTRAL APPALACHIANS, AND MID-ATLANTIC DEC 11-14. FREEZING TEMPERATURES MAY  
EXTEND AS FAR SOUTH AS THE NORTHERN FLORIDA PENINSULA, WHILE SUB-ZERO MINIMUM  
TEMPERATURES COULD SHIFT INTO THE MIDWEST.  
 
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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