929  
FXUS21 KWNC 242101  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST JANUARY 24 2018  
 
SYNOPSIS: A FRONTAL SYSTEM IS PREDICTED TO CROSS THE EASTERN HALF OF THE CONUS  
DURING THE FIRST FEW DAYS OF THE OUTLOOK PERIOD, FOLLOWED BY A BROAD AREA OF  
SURFACE HIGH PRESSURE. SEVERAL LOW PRESSURE SYSTEMS ARE FORECAST TO MOVE ACROSS  
THE PACIFIC NORTHWEST DURING THIS SAME PERIOD, MAINTAINING AN EXTENDED PERIOD  
OF STORMY CONDITIONS. ELSEWHERE, BROAD LOW PRESSURE CHURNING OVER THE GULF OF  
ALASKA IS ANTICIPATED TO MAINTAIN INCLEMENT WEATHER CONDITIONS ACROSS SOUTHERN  
ALASKA, THOUGH NO HAZARDS ARE EXPECTED AT THIS TIME. DURING THE WEEK-2 PERIOD,  
UNSEASONABLY COLD AIR IS PREDICTED TO OVERSPREAD THE ALASKA PANHANDLE, AND  
NORTHWESTERN AND NORTH-CENTRAL PORTIONS OF THE CONUS, WHILE THE BEST CHANCE FOR  
HAZARDOUS PRECIPITATION IS OVER EASTERN PORTIONS OF THE LOWER 48 STATES.  
 
HAZARDS  
 
HEAVY RAIN FOR THE CENTRAL AND EASTERN GULF COAST REGION, SAT-SUN, JAN 27-28.  
 
PERIODS OF HEAVY PRECIPITATION (MOUNTAIN SNOW AND VALLEY RAIN) FOR THE PACIFIC  
NORTHWEST, SAT-TUE, JAN 27-30.  
 
HEAVY PRECIPITATION FOR NORTHERN IDAHO, SAT-SUN, JAN 27-28.  
 
HIGH WINDS FOR THE PACIFIC NORTHWEST COAST, SAT-WED, JAN 27-31.  
 
HIGH SIGNIFICANT WAVE HEIGHTS FOR THE PACIFIC NORTHWEST COAST, SAT-WED, JAN  
27-31.  
 
FLOODING POSSIBLE IN WESTERN WASHINGTON STATE.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR FAR EASTERN ALASKA (INCLUDING  
THE PANHANDLE), AND FROM WASHINGTON AND NORTHERN IDAHO EASTWARD ACROSS THE  
NORTHERN AND CENTRAL PLAINS TO THE UPPER AND MIDDLE MISSISSIPPI VALLEY,  
THU-TUE, FEB 1-6.  
 
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES ALONG THE NORTHERN TIER OF  
STATES FROM WASHINGTON TO MINNESOTA (INCLUDING SOUTH DAKOTA), SUN-TUE, FEB 4-6.  
 
SLIGHT RISK OF HEAVY PRECIPITATION FOR THE MIDDLE MISSISSIPPI VALLEY  
NORTHEASTWARD ACROSS THE OHIO VALLEY AND NORTHEAST, AND MOST OF THE REMAINING  
EAST COAST REGION, THU-SAT, FEB 1-3.  
 
MODERATE RISK OF HEAVY PRECIPITATION FOR MIDDLE MISSISSIPPI VALLEY, OHIO  
VALLEY, NORTHERN HALF OF THE APPALACHIANS, AND EAST COAST FROM SOUTHWESTERN NEW  
ENGLAND TO NORTHERN VIRGINIA, THU-SAT, FEB 1-3.  
 
FROZEN PRECIPITATION FOR EASTERN MISSOURI NORTHEASTWARD THROUGH THE LOWER GREAT  
LAKES REGION, THU-SAT, FEB 1-3.  
 
SEVERE DROUGHT FOR PARTS OF THE GREAT PLAINS, SOUTHWEST, MIDDLE AND LOWER  
MISSISSIPPI VALLEY, AND SOUTHEAST.  
 
DETAILED SUMMARY  
 
FOR SATURDAY JANUARY 27 - WEDNESDAY JANUARY 31: A COMPLEX FRONTAL SYSTEM WITH  
SEVERAL WAVES OF LOW PRESSURE ALONG ITS PRIMARY COLD FRONT IS FORECAST TO  
TRANSIT THE EASTERN HALF OF THE CONUS EARLY IN THE PERIOD. PRECIPITATION IS  
EXPECTED TO REACH MARGINALLY HEAVY THRESHOLDS (1.5-2.0 INCHES) OVER THE WEEKEND  
(JAN 27-28) ACROSS THE CENTRAL AND EASTERN GULF COAST REGION.  
 
A SUBTROPICAL MOISTURE PLUME DIRECTED TOWARDS THE PACIFIC NORTHWEST IS EXPECTED  
TO RESULT IN PERIODS OF HEAVY PRECIPITATION (MOUNTAIN SNOW AND VALLEY RAIN)  
FROM JAN 27-30. DURING THE FIRST TWO DAYS OF THIS SO-CALLED ATMOSPHERIC RIVER  
EVENT, PRECIPITATION AMOUNTS (LIQUID EQUIVALENT) ARE FORECAST TO RANGE ANYWHERE  
FROM 2-9 INCHES, FOLLOWED BY AN ADDITIONAL 3-4 INCHES DURING THE SUBSEQUENT  
TWO-DAY PERIOD. HIGH WIND SPEEDS AND HIGH SIGNIFICANT WAVE HEIGHTS ARE OTHER  
EXPECTED HAZARDS INDICATED FOR THE PACIFIC NORTHWEST DURING THE 3-7 DAY PERIOD.  
WINDS OF 40-45 KNOTS, AND SIGNIFICANT WAVE HEIGHTS OF AT LEAST 20-25 FEET ARE  
FORECAST. IN THE HIGHER ELEVATIONS OF NORTHERN IDAHO, LIQUID EQUIVALENT  
PRECIPITATION AMOUNTS ARE EXPECTED TO RANGE FROM 2.5-3.0 INCHES DURING JAN  
27-28. ACCORDING TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN SPOKANE,  
WA, A FEW INCHES OF SNOW EARLY IN THE PERIOD MAY BE FOLLOWED BY A SIGNIFICANT  
RISING OF SNOW LEVELS TO PERHAPS 5000-6000 FEET.  
 
FLOODING IS POSSIBLE IN PARTS OF WESTERN WASHINGTON, RELATED TO HEAVY  
PRECIPITATION THAT HAS ALREADY FALLEN, AND IS PREDICTED TO FALL IN THE NEXT  
WEEK.  
 
SURFACE LOW PRESSURE CHURNING OVER THE GULF OF ALASKA IS ANTICIPATED TO  
MAINTAIN INCLEMENT WEATHER CONDITIONS ACROSS SOUTHERN ALASKA, WITH SURFACE HIGH  
PRESSURE PREDICTED TO PREVAIL OVER APPROXIMATELY THE NORTHERN TWO-THIRDS OF THE  
STATE.  
 
FOR THURSDAY FEBRUARY 01 - WEDNESDAY FEBRUARY 07: AN ARCTIC AIR MASS IS  
FORECAST TO OVERSPREAD FAR EASTERN ALASKA (INCLUDING THE PANHANDLE), AND  
PORTIONS OF THE NORTHWESTERN AND NORTH-CENTRAL CONUS DURING THIS PERIOD,  
WARRANTING A SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES (FEB 1-6). A  
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES EXTENDS FROM WASHINGTON STATE  
TO THE DAKOTAS, FROM FEB 4-6. AS ARCTIC AIR SPREADS FARTHER EAST AND SOUTH, AND  
INCREASINGLY MOIST GULF AIR STREAMS NORTHWARD OUT AHEAD OF IT, THE STAGE MAY BE  
SET FOR THE DEVELOPMENT OF A SIGNIFICANT BAROCLINIC ZONE AND RESULTANT WINTER  
STORM ACROSS THE EAST-CENTRAL AND NORTHEASTERN CONUS DURING THE FIRST FEW DAYS  
OF WEEK-2. THEREFORE, A SLIGHT RISK OF HEAVY PRECIPITATION IS INDICATED FROM  
THE MIDDLE MISSISSIPPI VALLEY NORTHEASTWARD ACROSS THE OHIO VALLEY AND  
NORTHEAST, AND MOST OF THE REMAINING EAST COAST REGION (FEB 1-3). A MODERATE  
RISK OF HEAVY PRECIPITATION IS INDICATED FOR THE MIDDLE MISSISSIPPI VALLEY,  
OHIO VALLEY, NORTHERN HALF OF THE APPALACHIANS, AND EAST COAST FROM  
SOUTHWESTERN NEW ENGLAND TO NORTHERN VIRGINIA (FEB 1-3). WITHIN THIS MODERATE  
RISK AREA, FROZEN PRECIPITATION IS DEPICTED FROM EASTERN MISSOURI NORTHEASTWARD  
THROUGH THE LOWER GREAT LAKES REGION (FEB 1-3).  
 
THE U.S. DROUGHT MONITOR, VALID ON JANUARY 16, 2018 INDICATES AN INCREASE IN  
THE COVERAGE OF SEVERE TO EXCEPTIONAL DROUGHT (D2-D4) FROM 8.70% LAST WEEK TO  
10.03% THIS WEEK. SEVERE DROUGHT CONTINUED TO EXPAND ACROSS THE SOUTHERN GREAT  
PLAINS WITH NEARLY HALF OF OKLAHOMA DESIGNATED WITH SEVERE DROUGHT.  
 
FORECASTER: ANTHONY ARTUSA  
 

 
 
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