425  
FXUS21 KWNC 311927  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST JANUARY 31 2018  
 
SYNOPSIS: A MID-LEVEL TROUGH IS LIKELY TO AFFECT THE EASTERN TWO-THIRDS OF THE  
CONTINENTAL U.S. OVER THE NEXT TWO WEEKS, WHILE A MID-LEVEL HIGH PRESSURE  
CENTER IS FORECAST OFF THE WESTERN COAST. SEVERAL SURFACE LOW PRESSURE SYSTEMS  
ARE EXPECTED TO BRING FRONTAL ACTIVITY TO THE PACIFIC NORTHWEST AND ROCKIES,  
WHILE A STORM SYSTEM COULD AFFECT THE EAST COAST LATE THIS WEEKEND INTO EARLY  
NEXT WEEK. WEEK-2 IS LIKELY TO FEATURE A MOSTLY DRY PATTERN WITH SURFACE HIGH  
PRESSURE SYSTEMS MOVING SOUTH OUT OF CANADA OVER THE CENTRAL AND EASTERN U.S.  
THE FORECAST CIRCULATION OVER ALASKA IS FORECAST TO BE SIMILARLY STATIONARY  
DURING THIS PERIOD, WITH A SERIES OF LOW PRESSURE SYSTEMS OVER THE ALEUTIAN  
ISLANDS AND RIDGING IN THE NORTHERN PART OF THE STATE, AS WELL AS THE PANHANDLE.  
 
HAZARDS  
 
HEAVY RAIN ACROSS PORTIONS OF THE PACIFIC NORTHWEST, SAT-SUN, FEB 3-FEB 4.  
 
HEAVY SNOW FOR MOUNTAINOUS REGIONS OF THE PACIFIC NORTHWEST, SAT-SUN, FEB 3-FEB  
4.  
 
HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN AND CENTRAL ROCKIES, THE NORTHERN  
GREAT BASIN, AND THE NORTHERN HIGH PLAINS, SAT-WED, FEB 3-FEB 7.  
 
HEAVY SNOW ACROSS PORTIONS OF THE MID-ATLANTIC AND NORTHEAST, SUN-MON, FEB  
4-FEB 5.  
 
MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE CENTRAL AND NORTHERN  
PLAINS, THE GREAT LAKES, AND THE UPPER MISSISSIPPI VALLEY, SAT-WED, FEB 3-FEB 7.  
 
MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF SOUTHEAST ALASKA, SAT, FEB 3.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE PLAINS, THE  
MID-ATLANTIC, THE MISSISSIPPI VALLEY, THE CENTRAL AND SOUTHERN APPALACHIANS,  
THE TENNESSEE VALLEY, THE GREAT LAKES, THE NORTHEAST, THE SOUTHEAST, AND THE  
OHIO VALLEY, THU-WED, FEB 8-FEB 14.  
 
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE NORTHEAST,  
THE CENTRAL APPALACHIANS, THE MIDDLE AND UPPER MISSISSIPPI VALLEY, THE  
MID-ATLANTIC, THE GREAT LAKES, AND THE OHIO VALLEY, THU-TUE, FEB 8-FEB 13.  
 
SEVERE DROUGHT ACROSS THE PLAINS, THE CENTRAL AND SOUTHERN ROCKIES, THE CENTRAL  
GREAT BASIN, THE TENNESSEE VALLEY, THE MIDDLE AND LOWER MISSISSIPPI VALLEY, THE  
MID-ATLANTIC, THE SOUTHEAST, AND THE SOUTHWEST.  
 
DETAILED SUMMARY  
 
FOR SATURDAY FEBRUARY 03 - WEDNESDAY FEBRUARY 07: A SERIES OF SURFACE HIGH  
PRESSURE SYSTEMS ARE FORECAST TO MOVE SOUTH OVER THE CENTRAL PLAINS THROUGHOUT  
THE WEEK, AFFECTING THE CENTRAL AND EASTERN CONUS. AN UPPER-LEVEL SHORTWAVE  
EMBEDDED IN THE LONG-WAVE TROUGH IS EXPECTED TO AFFECT THE NORTHWEST AT THE  
START OF THE PERIOD, AND MAY PHASE WITH ANOTHER RAPID MOVING SHORTWAVE OVER THE  
EASTERN CONUS LATE THIS WEEKEND AND EARLY NEXT WEEK. BY SUNDAY AND MONDAY, THIS  
SHOULD LEAD TO THE FORMATION OF A COASTAL STORM THAT IS FORECAST TO MOVE  
QUICKLY NORTHEASTWARD OFF THE NORTHEAST COAST. A WIDESPREAD 4-8 INCH SNOWFALL  
EVENT IS POSSIBLE FOR PARTS OF THE NORTHEAST AND MID-ATLANTIC, MAINLY NORTHWEST  
OF THE I-95 CORRIDOR AND INTO THE CENTRAL APPALACHIANS.  
 
MUCH BELOW-NORMAL TEMPERATURES ARE PREDICTED FOR THE NORTH CENTRAL PLAINS,  
GREAT LAKES, AND UPPER MIDWEST FROM FEB 3-7, DUE TO THE SERIES OF HIGH PRESSURE  
SYSTEMS CAUSING A SERIES OF COLD AIR OUTBREAKS FROM CANADA. MINIMUM  
TEMPERATURES 12 DEGREES F BELOW NORMAL OR COLDER ARE LIKELY FOR MOST OF THE  
DAYS IN THIS PERIOD WITHIN THE DEPICTED REGION.  
 
THE NORTHWEST AND NORTHERN ROCKIES ARE EXPECTED TO EXPERIENCE TWO DISTINCT  
SHORTWAVE TROUGHS DURING THE PERIOD. HEAVY RAIN (EXCEEDING 1.5" IN 24 HOURS) IS  
LIKELY IN THE WESTERN PART OF WASHINGTON STATE THIS WEEKEND, WITH HEAVY SNOW IN  
THE CASCADES (LIQUID EQUIVALENT EXCEEDING 1.5"), THOUGH SNOW LEVELS ARE  
FORECAST TO BE QUITE HIGH. HEAVY SNOW IS ALSO LIKELY ACROSS THE NORTHERN  
ROCKIES FOR SEVERAL DAYS OF THIS PERIOD DUE TO THE AFOREMENTIONED SHORTWAVES  
TROUGHS AND UPSLOPE FLOW.  
 
FOR ALASKA, A FEW SURFACE LOW PRESSURE SYSTEMS ARE FORECAST TO MOVE THROUGH THE  
GULF OF ALASKA, PERIODICALLY AFFECTING THE SOUTHERN PART OF THE STATE.  
HAZARDOUS CONDITIONS ARE NOT FORECAST AT THIS TIME. A SURFACE HIGH IS LIKELY TO  
REMAIN ENTRENCHED OVER THE NORTHERN HALF OF ALASKA THROUGH THE PERIOD. MUCH  
BELOW-NORMAL TEMPERATURES, LIKELY 20-30 DEGREES F NEGATIVE ANOMALIES, ARE  
EXPECTED IN THE PANHANDLE AND ALONG THE SOUTHERN GULF COAST ON SATURDAY, WITH  
MODERATION EXPECTED THEREAFTER. ADDITIONALLY, WITH THIS STRONG SURFACE HIGH,  
CONDITIONS APPEAR FAVORABLE FOR STRONG GAP WINDS OVER THE SOUTHERN PART OF THE  
STATE.  
 
FOR THURSDAY FEBRUARY 08 - WEDNESDAY FEBRUARY 14: MID-LEVEL PATTERNS PRESENT IN  
DAYS 3-7 ARE LIKELY TO PERSIST THROUGH WEEK-2. THE GFS AND ECMWF ENSEMBLE MEAN  
SOLUTIONS CONTINUE TO DIVERGE IN WEEK-2, HOWEVER, WITH THE ECMWF BEING MORE  
PROGRESSIVE OVERALL, AND THUS MILDER ESPECIALLY OVER THE CENTRAL CONUS. SLIGHT  
AND MODERATE RISKS OF MUCH BELOW NORMAL TEMPERATURE CONTINUE TO BE DEPICTED FOR  
PARTS OF THE EASTERN CONUS WHERE ENHANCED ODDS (20 AND 40 PERCENT,  
RESPECTIVELY) OF MINIMUM TEMPERATURES BELOW THE 15TH CLIMATOLOGICAL PERCENTILE  
ARE FORECAST FOR TWO OR MORE DAYS. STATISTICAL GUIDANCE BASED ON THE MJO FAVORS  
A COLDER SOLUTION, ESPECIALLY LATER IN THE PERIOD.  
 
ANOMALOUS RIDGING IS FORECAST TO REMAIN INTACT OVER THE WESTERN CONUS, WITH  
MUCH ABOVE NORMAL TEMPERATURES EXPECTED DURING THE WEEK-2 PERIOD. WHILE THIS IS  
NOT DEPICTED ON THE MAP DUE TO THE COOL CLIMATOLOGY, THERE APPEARS TO BE  
DRAMATICALLY INCREASED ODDS OF RECORD HIGH TEMPERATURES, ESPECIALLY EARLY IN  
THE WEEK AND CENTERED OVER CALIFORNIA AND THE SOUTHWEST. COUPLED WITH  
ANOMALOUSLY LOW SOIL MOISTURE VALUES AND ANOMALOUS OFFSHORE FLOW, THE FIRE  
WEATHER RISK IS ELEVATED DURING WEEK-2.  
 
THE U.S. DROUGHT MONITOR, VALID ON JANUARY 23, 2018 INDICATES AN INCREASE IN  
THE COVERAGE OF SEVERE TO EXCEPTIONAL DROUGHT (D2-D4) FROM 10.03% LAST WEEK TO  
13.60% THIS WEEK. SEVERE DROUGHT CONTINUED TO EXPAND ACROSS THE SOUTHERN GREAT  
PLAINS AND SOUTHWEST THIS PAST WEEK.  
 
FORECASTER: STEPHEN BAXTER  
 

 
 
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