963  
FXUS21 KWNC 292019  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST NOVEMBER 29 2017  
 
SYNOPSIS: AT THE START OF THE PERIOD, LOW PRESSURE AT THE SURFACE AND MID  
LEVELS IS EXPECTED TO MOVE FROM THE 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 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. STRONG AREAS OF SURFACE LOW  
PRESSURE ARE PREDICTED TO MOVE ACROSS THE BERING SEA, ALEUTIANS, AND GULF OF  
ALASKA DEC 2-6. DURING WEEK-2, STRONG MID-LEVEL HIGH PRESSURE IS FORECAST ALONG  
THE WEST COAST AND OVER ALASKA, WHILE STRONG MID-LEVEL LOW PRESSURE IS  
PREDICTED OVER THE EAST-CENTRAL AND EASTERN PARTS OF THE LOWER 48 STATES.  
 
HAZARDS  
 
HEAVY SNOW FOR PARTS OF THE CASCADES AND BITTERROOTS, SAT, DEC 2.  
 
HEAVY RAIN FOR PARTS OF THE LOWER MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS,  
MON-TUE, DEC 4-5.  
 
HIGH SIGNIFICANT WAVE HEIGHTS FOR PARTS OF THE ALEUTIANS AND ALASKA PANHANDLE,  
SAT, DEC 2.  
 
HIGH WINDS FOR PARTS OF THE ALEUTIANS, ALASKA PENINSULA, SOUTH COASTAL MAINLAND  
ALASKA, AND THE ALASKA PANHANDLE, SUN-TUE, DEC 3-5.  
 
HIGH SIGNIFICANT WAVE HEIGHTS FOR PARTS OF SOUTH COASTAL MAINLAND ALASKA AND  
THE ALASKA PANHANDLE, MON-TUE, DEC 4-5.  
 
HEAVY PRECIPITATION ACROSS PORTIONS OF THE ALASKA PANHANDLE AND SOUTHEASTERN  
MAINLAND ALASKA, MON-TUE, DEC 4-5.  
 
FLOODING OCCURRING OR IMMINENT ACROSS A SMALL PORTION OF WEST-CENTRAL WASHINGTON  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FROM TEXAS, ALONG THE GULF COAST,  
UP THROUGH PARTS OF THE OHIO AND TENNESSEE VALLEYS, MIDWEST AND MID-ATLANTIC,  
THU-WED, DEC 7-DEC 13.  
 
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF THE OHIO AND  
TENNESSEE VALLEYS, SAT-MON, DEC 9-11.  
 
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 SATURDAY DECEMBER 02 - WEDNESDAY DECEMBER 06: LOW PRESSURE MOVING ONSHORE  
FROM THE EAST PACIFIC TO THE PACIFIC NORTHWEST AND NORTHERN ROCKIES BRINGS THE  
LIKELIHOOD OF HEAVY SNOW (AMOUNTS IN EXCESS OF 6 INCHES IN 24 HOURS) FOR PARTS  
OF THE CASCADES AND BITTERROOTS DEC 2. THE PRECIPITATION ASSOCIATED WITH THIS  
SYSTEM IS EXPECTED TO PROLONG FLOODING OCCURRING OR IMMINENT FOR A SMALL  
PORTION OF WEST-CENTRAL WASHINGTON.  
 
AS HIGH PRESSURE MOVES OFF THE EAST COAST DURING DEC 4, 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  
FOCUSING MECHANISM FOR HEAVY RAIN. AMOUNTS IN EXCESS OF 1 INCH IN 24 HOURS ARE  
ANTICIPATED FOR PARTS OF THE LOWER MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS DEC  
4-5.  
 
STRONG AREAS OF LOW PRESSURE ARE ANTICIPATED TO IMPACT THE BERING SEA,  
ALEUTIANS, ALASKA PENINSULA AND GULF OF ALASKA DEC 2-6. HIGH SIGNIFICANT WAVE  
HEIGHTS (IN EXCESS OF 20 FEET) ARE FORECAST FOR PARTS OF THE ALEUTIANS AND  
ALASKA PANHANDLE DEC 2, AND FOR PARTS OF SOUTH COASTAL MAINLAND ALASKA AND THE  
ALASKA PANHANDLE DEC 4-5. 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 3-5. 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 4-5. STRONG OFFSHORE FLOW  
MAY RESULT IN HIGH WINDS ON THE WEST COAST OF ALASKA FROM POINT HOPE TO BARROW  
BUT MODEL UNCERTAINTY PRECLUDES THE SPECIFICATION OF A HAZARD SHAPE AT THE  
CURRENT TIME.  
 
FOR THURSDAY DECEMBER 07 - WEDNESDAY DECEMBER 13: 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 FROM TEXAS, ALONG THE GULF COAST, UP THROUGH PARTS OF  
THE OHIO AND TENNESSEE VALLEYS, MIDWEST AND MID-ATLANTIC DEC 7-13, AND A  
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF THE OHIO AND  
TENNESSEE VALLEYS DEC 9-11. IT IS LIKELY THAT TEMPERATURES WILL DROP BELOW  
FREEZING IN PORTIONS OF THESE AREAS, SO THERE IS A POTENTIAL FOR OVERNIGHT  
FREEZES FOR PARTS OF THE INTERIOR SOUTHEAST.  
 
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 21, SHOWS SEVERE TO EXCEPTIONAL  
(D2-D4) DROUGHT COVERS 4.14% OF THE CONVENTIONAL UNITED STATES, A SLIGHT  
INCREASE OF 0.62% COVERAGE FROM THE PREVIOUS WEEK. AREAS OF SEVERE DROUGHT HAVE  
INCREASED IN ARKANSAS AND TEXAS.  
 
FORECASTER: RANDY SCHECHTER  
 

 
 
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