160  
FXUS21 KWNC 082109  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST NOVEMBER 08 2017  
 
SYNOPSIS: A SERIES OF COLD FRONTS ARE PREDICTED TO MOVE ACROSS THE LOWER 48  
STATES THROUGHOUT THE 3 TO 7 DAY PERIOD. SURFACE HIGH PRESSURE IS EXPECTED TO  
BUILD ACROSS THE CONTIGUOUS U.S. BEHIND THESE COLD FRONTS. STRONG ONSHORE FLOW  
IS ANTICIPATED FOR THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA THROUGHOUT  
MUCH OF THE 3 TO 7 DAY PERIOD AND PART OF WEEK-2. SURFACE LOW PRESSURE SYSTEMS  
ARE FORECAST TO FORM OVER THE BERING SEA AND GULF OF ALASKA. SURFACE HIGH  
PRESSURE IS EXPECTED TO BUILD ACROSS MANY PARTS OF MAINLAND ALASKA THROUGHOUT  
THE 3 TO 7 DAY PERIOD AND PART OF WEEK-2.  
 
HAZARDS  
 
MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE GREAT LAKES, THE  
MID-ATLANTIC, THE NORTHEAST, THE CENTRAL APPALACHIANS, AND THE OHIO VALLEY,  
SAT, NOV 11.  
 
HIGH WINDS ACROSS COASTAL PORTIONS OF NORTHERN CALIFORNIA AND THE PACIFIC  
NORTHWEST, MON, NOV 13.  
 
HEAVY PRECIPITATION ACROSS PORTIONS OF CALIFORNIA, THE PACIFIC NORTHWEST, AND  
THE NORTHERN GREAT BASIN, SUN-WED, NOV 12-NOV 15.  
 
HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN ROCKIES AND THE NORTHERN GREAT  
BASIN, MON-WED, NOV 13-NOV 15.  
 
HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE NORTHERN PLAINS, THE  
NORTHERN ROCKIES, THE CENTRAL ROCKIES, THE NORTHERN GREAT BASIN, AND THE  
PACIFIC NORTHWEST, WED, NOV 15.  
 
HEAVY SNOW ACROSS PORTIONS OF NORTHWESTERN MAINLAND ALASKA, SUN, NOV 12.  
 
HIGH WINDS ACROSS WESTERN PORTIONS OF MAINLAND ALASKA, SAT-SUN, NOV 11-NOV 12.  
 
POSSIBLE FLOODING ACROSS COASTAL PORTIONS OF WESTERN MAINLAND ALASKA, SAT-SUN,  
NOV 11-12.  
 
MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE ALASKA PANHANDLE AND THE  
SOUTHERN HALF OF MAINLAND ALASKA, TUE, NOV 15.  
 
HEAVY PRECIPITATION ACROSS PORTIONS OF CALIFORNIA, THE PACIFIC NORTHWEST, AND  
THE NORTHERN GREAT BASIN, THU-SAT, NOV 16-NOV 18.  
 
HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE NORTHERN PLAINS, THE  
NORTHERN ROCKIES, THE CENTRAL ROCKIES, THE NORTHERN GREAT BASIN, AND THE  
PACIFIC NORTHWEST, THU, NOV 16.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE ALASKA  
PANHANDLE, MAINLAND ALASKA, AND THE ALEUTIANS, THU-SUN, NOV 16-NOV 19.  
 
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE ALASKA  
PANHANDLE AND THE SOUTH COAST OF ALASKA, THU-FRI, NOV 16-NOV 17.  
 
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF EASTERN  
INTERIOR MAINLAND ALASKA, THU-SAT, NOV 16-NOV 18.  
 
FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE SOUTHEAST.  
 
SEVERE DROUGHT ACROSS HAWAII, THE SOUTHERN PLAINS, THE NORTHERN PLAINS, THE  
NORTHERN ROCKIES, AND THE SOUTHWEST.  
 
DETAILED SUMMARY  
 
FOR SATURDAY NOVEMBER 11 - WEDNESDAY NOVEMBER 15: SURFACE HIGH PRESSURE IS  
PREDICTED TO BUILD ACROSS MUCH OF THE EASTERN HALF OF THE CONUS AT THE  
BEGINNING OF THE PERIOD. THIS PATTERN IS EXPECTED TO BRING IN COLD CANADIAN AIR  
AND SUPPORT MUCH BELOW NORMAL TEMPERATURES ACROSS PARTS OF THE GREAT LAKES, THE  
MID-ATLANTIC, THE NORTHEAST, THE CENTRAL APPALACHIANS, AND THE OHIO VALLEY NOV  
11. AREAS FROM THE CAROLINAS TO THE MID-ATLANTIC AND LONG ISLAND COULD SEE  
THEIR FIRST FREEZE OF THE YEAR. FREEZING TEMPERATURES ARE FORECAST FOR BOTH  
SATURDAY AND SUNDAY MORNING, FOR AREAS EAST OF THE APPALACHIANS.  
 
AN ACTIVE PERIOD IS FORECAST FOR THE NORTHWEST QUADRANT OF THE COUNTRY AS A  
SERIES OF SURFACE LOWS APPROACH THE PACIFIC NORTHWEST. AS THE MOISTURE MOVES  
INLAND, EPISODES OF HEAVY SNOWS ARE FORECAST OVER IDAHO AND IN THE VICINITY OF  
YELLOWSTONE NATIONAL PARK DURING NOV 12 TO 15. THIS PATTERN ALSO FAVORS  
MODERATE TO LOCALLY HEAVY RAINS (1-2 INCHES WITH LOCALLY HIGHER AMOUNTS) WITH  
SNOW AT HIGHER ELEVATIONS ARE PREDICTED FOR THE PACIFIC NORTHWEST DURING  
SATURDAY. RIVERS ARE LIKELY TO RISE QUICKLY AS THIS SYSTEM SHOULD HAVE A GOOD  
FEED OF MOISTURE. MODEL FORECASTS SHOW ANOTHER SYSTEM MOVING INTO THE AREA ON  
SUNDAY, WITH LINGERING HEAVY PRECIPITATION IMPACTS INTO THE MIDDLE OF WEEK-2.  
HEAVY SNOWS ARE AGAIN LIKELY TO IMPACT THE BITTERROOTS AND SOUTHWARD TO  
YELLOWSTONE. COASTAL PARTS OF THE PACIFIC NORTWEST MAY EXPERIENCE HIGH WINDS  
(40 KNOTS OR GREATER) AS WELL AS THE CENTRAL PLAINS, THE NORTHERN PLAINS, THE  
NORTHERN ROCKIES, THE CENTRAL ROCKIES, THE NORTHERN GREAT BASIN, AND THE  
PACIFIC NORTHWEST (30 KNOTS OR GREATER).  
 
A LOW-PRESSURE SYSTEM IS FORECAST TO DEEPEN OVER NORTHWESTERN ALASKA, BRINGING  
HIGH WINDS (IN EXCESS OF 30 KNOTS) TO THE WESTERN COAST OF ALASKA NOV 11 TO 12.  
COASTAL FLOODING MAY BE A POTENTIALLY SERIOUS CONCERN TO SEVERAL NORTHWEST  
ALASKA COMMUNITIES ASSOCIATED WITH THE STRONG ONSHORE FLOW ACROSS WESTERN  
MAINLAND ALASKA. HEAVY SNOW IS LIKELY TO OVERSPREAD CENTRAL ALASKA, WITH RATIOS  
LIKELY TOPPING 15 TO 1, AND AN NEARLY AN INCH OF LIQUID EQUIVALENT PREDICTED.  
REGIONS WITH HIGHER TERRAIN MAY GET ENHANCED SNOW AMOUNTS. TOWARD THE END OF  
THE PERIOD, SURFACE HIGH PRESSURE IS ANTICIPATED TO BUILD ACROSS THE MAJORITY  
OF MAINLAND ALASKA, BRINGING COLD AIR TO PARTS OF THE SOUTHERN HALF OF ALASKA  
AND THE ALASKA PANHANDLE NOV 15, WITH HIGH TEMPERATURES 24 TO 32 DEG F BELOW  
NORMAL.  
 
FOR THURSDAY NOVEMBER 16 - WEDNESDAY NOVEMBER 22: STRONG ONSHORE FLOW IS  
EXPECTED TO CONTINUE FROM THE 3 TO 7 DAY PERIOD INTO THE MIDDLE OF WEEK-2. THIS  
PATTERN MAY SUPPORT INCREASED CHANCES FOR HEAVY RAIN AND SNOW AND HIGH  
ELEVATION SNOW NOV 16 TO 18. A PROLONGED PERIOD OF HEAVY PRECIPITATION MAY LEAD  
TO LOCALIZED AREAS WITH FLOODING. SURFACE LOW PRESSURE ACROSS THE PACIFIC  
NORTHWEST IS ALSO ANTICIPATED TO PERSIST INTO THE BEGINNING OF WEEK-2. THIS  
PATTERN IS LIKELY TO EXTEND THE INCREASED LIKELIHOOD OF HIGH WINDS ACROSS PARTS  
OF THE CENTRAL PLAINS, THE NORTHERN PLAINS, THE NORTHERN ROCKIES, THE CENTRAL  
ROCKIES, THE NORTHERN GREAT BASIN, AND THE PACIFIC NORTHWEST, INTO NOV 16.  
 
SURFACE HIGH PRESSURE ACROSS THE MAJORITY OF MAINLAND ALASKA IS ANTICIPATED TO  
EXTEND FROM THE 3 TO 7 DAY PERIOD INTO THE MIDDLE OF WEEK-2. AN AREA OF SLIGHT  
RISK IS HIGHLIGHTED ACROSS A BROAD AREA OF MAINLAND ALASKA NOV 16 TO 19 FOR  
MUCH BELOW NORMAL TEMPERATURES (WHERE THE GEFS REFORECAST TOOL INDICATES A 20%  
CHANCE OR GREATER OF REACHING THE LOWEST 15TH PERCENTILE). MODERATE RISK AREAS  
ARE IDENTIFIED ACROSS PARTS OF EASTERN MAINLAND INTERIOR ALASKA (NOV 16 TO 18)  
AND THE SOUTH COAST OF ALASKA AND THE ALASKA PANHANDLE (NOV 16 TO 17).  
 
THE U.S. DROUGHT MONITOR, VALID ON OCTOBER 31, INDICATES THAT SEVERE TO  
EXCEPTIONAL (D2-D4) DROUGHT COVERS 2.67 PERCENT OF THE CONTINENTAL U.S., WHICH  
IS A SLIGHT INCREASE FROM 2.58 PERCENT LAST WEEK. THE WORST CONDITIONS CONTINUE  
TO BE OVER THE NORTHERN GREAT PLAINS REGION. THE MOST SIGNIFICANT IMPROVEMENTS  
MADE TO THE DROUGHT DEPICTION THIS WEEK WERE OVER THE NORTHEAST, WHERE MUCH OF  
THE REGION RECEIVED MORE THAN 4 INCHES OF RAIN DURING THE PAST WEEK.  
 
FORECASTER: MELISSA OU  
 

 
 
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