519  
FXUS21 KWNC 091953  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST NOVEMBER 09 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  
 
HEAVY PRECIPITATION ACROSS PORTIONS OF NORTHERN CALIFORNIA AND THE PACIFIC  
NORTHWEST, MON-THU, NOV 13-NOV 16.  
 
HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN ROCKIES AND THE NORTHERN GREAT  
BASIN, MON-THU, NOV 13-NOV 16.  
 
HIGH WINDS ACROSS COASTAL PORTIONS OF CALIFORNIA AND THE PACIFIC NORTHWEST,  
SUN-THU, NOV 12-NOV 16.  
 
HIGH SIGNIFICANT WAVE HEIGHTS FOR COASTAL PORTIONS OF THE PACIFIC NORTHWEST,  
THU, NOV 16.  
 
HIGH WINDS ACROSS PORTIONS OF THE NORTHERN GREAT BASIN, MON, NOV 13.  
 
HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE CENTRAL GREAT BASIN, THE  
NORTHERN PLAINS, THE NORTHERN ROCKIES, THE CENTRAL ROCKIES, AND THE NORTHERN  
GREAT BASIN, THU, NOV 16.  
 
HIGH WINDS ACROSS PORTIONS OF THE GREAT LAKES, WED, NOV 15.  
 
HEAVY SNOW ACROSS PORTIONS OF MAINLAND ALASKA, SUN, NOV 12.  
 
HIGH WINDS ACROSS WESTERN PORTIONS OF MAINLAND ALASKA, SUN, NOV 12.  
 
FLOODING POSSIBLE ACROSS COASTAL PORTIONS OF WESTERN MAINLAND ALASKA, SUN, NOV  
12.  
 
HIGH WINDS ACROSS THE SOUTH COAST OF ALASKA, MON, NOV 13.  
 
MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF SOUTHEASTERN MAINLAND ALASKA,  
WED-THU, NOV 15-NOV 16.  
 
HIGH WINDS ACROSS COASTAL PORTIONS OF NORTHERN CALIFORNIA AND THE PACIFIC  
NORTHWEST, SAT, NOV 18.  
 
HEAVY PRECIPITATION ACROSS PORTIONS OF NORTHERN CALIFORNIA, THE PACIFIC  
NORTHWEST, AND THE NORTHERN GREAT BASIN, FRI-SUN, NOV 17-NOV 19.  
 
HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE NORTHERN PLAINS, AND THE  
NORTHERN ROCKIES, FRI, NOV 17.  
 
HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN ROCKIES AND THE NORTHERN GREAT  
BASIN, FRI-TUE, NOV 17-NOV 21.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE GREAT LAKES,  
THE MID-ATLANTIC, AND THE NORTHEAST, WED-THU, NOV 22-NOV 23.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE ALASKA  
PANHANDLE, MAINLAND ALASKA, AND THE ALEUTIANS, FRI-TUE, NOV 17-NOV 21.  
 
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF SOUTHEASTERN  
ALASKA, THE ALASKA PANHANDLE AND SOUTH COAST OF ALASKA, FRI-SAT, NOV 17-NOV 18.  
 
HIGH WINDS FOR PORTIONS OF THE SOUTH COAST OF ALASKA AND THE ALASKA PANHANDLE,  
FRI-SAT, NOV 17-NOV 18.  
 
FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF FLORIDA.  
 
SEVERE DROUGHT ACROSS PARTS OF THE THE LOWER AND MIDDLE MISSISSIPPI VALLEY, THE  
NORTHERN AND SOUTHERN PLAINS, THE NORTHERN ROCKIES, ARIZONA, AND HAWAII.  
 
DETAILED SUMMARY  
 
FOR SUNDAY NOVEMBER 12 - THURSDAY NOVEMBER 16: AN ACTIVE PERIOD IS FORECAST FOR  
THE NORTHWESTERN QUADRANT OF THE COUNTRY AS A SERIES OF SURFACE LOWS APPROACH  
THE PACIFIC NORTHWEST. AS THE MOISTURE MOVES INLAND, EPISODES OF HEAVY SNOWS  
(UP TO AN INCH OR GREATER OF LIQUID EQUIVALENT IN A 24-HOUR PERIOD) ARE  
FORECAST OVER IDAHO AND IN THE VICINITY OF YELLOWSTONE NATIONAL PARK DURING NOV  
13 TO 16. 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 AND NORTHERN CALIFORNIA NOV 13 TO 16. RIVERS ARE LIKELY  
TO RISE QUICKLY AS THIS SYSTEM SHOULD HAVE A GOOD FEED OF MOISTURE. COASTAL  
PARTS OF NORTHERN CALIFORNIA AND THE PACIFIC NORTWEST MAY EXPERIENCE HIGH WINDS  
NOV 12 TO 16 AS WELL AS THE NORTHERN GREAT BASIN NOV 13, AND THE CENTRAL  
PLAINS, THE CENTRAL GREAT BASIN, THE NORTHERN PLAINS, THE NORTHERN ROCKIES, THE  
CENTRAL ROCKIES, AND THE NORTHERN GREAT BASIN NOV 16. SUSTAINED WIND SPEEDS IN  
THESE HIGHLIGHTED AREAS MAY REACH 30 KNOTS GREATER, OR UP TO 40 KNOTS OR  
GREATER ACROSS COASTAL PARTS OF NORTHERN CALIFORNIA AND THE PACIFIC NORTHWEST.  
HIGH WINDS MAY SUPPORT HIGH SIGNIFICANT WAVE HEIGHTS ACROSS COASTAL PORTIONS OF  
THE PACIFIC NORTHWEST NOV 16 (21 FEET OR GREATER).  
 
A COLD FRONT IS EXPECT TO PASS ACROSS THE GREAT LAKES ON NOV 15, WHICH MAY  
SUPPORT HIGH WINDS IN THE GREAT LAKES AREA NOV 15. SUSTAINED WIND SPEEDS MAY  
REACH 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 12.  
COASTAL FLOODING AND EROSION MAY BE A POTENTIALLY SERIOUS CONCERN TO SEVERAL  
NORTHWEST ALASKA COMMUNITIES ASSOCIATED WITH THE STRONG ONSHORE FLOW ACROSS  
WESTERN MAINLAND ALASKA. HEAVY SNOW IS POSSIBLE ACROSS PARTS OF NORTHWEST  
ALASKA, WITH RATIOS POSSIBLY TOPPING 15 TO 1, AND AN NEARLY AN INCH OF LIQUID  
EQUIVALENT PREDICTED. REGIONS WITH HIGHER TERRAIN MAY GET ENHANCED SNOW  
AMOUNTS. IT SHOULD BE NOTED THAT THERE HAS BEEN SIGNIFICANT MODEL UNCERTAINTY  
AMONGST MODELS AND VARIOUS MODEL RUNS REGARDING THE INTENSITY OF THIS STORM AND  
ITS RESULTING IMPACTS.  
 
SURFACE LOW PRESSURE IS ANTICIPATED TO DEEPEN IN THE GULF OF ALASKA BY NOV 13,  
FAVORING HIGH WINDS ACROSS PARTS OF THE SOUTH COAST OF ALASKA. SUSTAINED WIND  
SPEEDS MAY REACH 40 KNOTS OR GREATER.  
 
 
 
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  
SOUTHEASTERN ALASKA NOV 15 TO 16, WITH HIGH TEMPERATURES 24 TO 32 DEG F BELOW  
NORMAL.  
 
FOR FRIDAY NOVEMBER 17 - THURSDAY NOVEMBER 23: STRONG ONSHORE FLOW ACROSS  
NORTHWESTERN CONUS IS EXPECTED TO CONTINUE FROM THE 3 TO 7 DAY PERIOD INTO THE  
MIDDLE OF WEEK-2. THIS PATTERN MAY SUPPORT INCREASED CHANCES FOR EPISODES OF  
HEAVY RAIN AND SNOW AND HIGH ELEVATION SNOW ACROSS PARTS OF THE PACIFIC  
NORTHWEST AND NORTHERN CALIFORNIA, NOV 17 TO 19. A PROLONGED PERIOD OF HEAVY  
PRECIPITATION MAY LEAD TO LOCALIZED AREAS WITH FLOODING. THIS PATTERN ALSO  
FAVORS HIGH WINDS (40 KNOTS OR GREATER) ACROSS COASTAL PARTS OF NORTHERN  
CALIFORNIA AND THE PACIFIC NORTHWEST NOV 18. PARTS OF THE CENTRAL PLAINS, THE  
NORTHERN PLAINS, AND THE NORTHERN ROCKIES MAY ALSO EXPERIENCE HIGH WINDS (30  
KNOTS OR GREATER) NOV 17. EPISODES OF LOCALLY HEAVY SNOW (ONE INCH OF LIQUID  
EQUIVALENT OR GREATER IN A 24-HOUR PERIOD) ACROSS PORTIONS OF THE NORTHERN  
ROCKIES AND THE NORTHERN GREAT BASIN MAY CONTINUE NOV 17 TO 21.  
 
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 17 TO 21 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 SOUTHEASTERN MAINLAND INTERIOR ALASKA (NOV 17 TO  
18) AND THE SOUTH COAST OF ALASKA AND THE ALASKA PANHANDLE (NOV 17 TO 18).  
ADDITIONALLY, THIS PATTERN MAY ALSO SUPPORT STRONG GAP WINDS (30 KNOTS OR  
GREATER) ACROSS THE GULF COAST OF ALASKA AND ALASKA PANHANDLE, NOV 17 TO 18.  
 
THE U.S. DROUGHT MONITOR, VALID ON NOV 7, INDICATES THAT SEVERE TO EXCEPTIONAL  
(D2-D4) DROUGHT COVERS 2.90 PERCENT OF THE CONTINENTAL U.S., WHICH IS A SLIGHT  
INCREASE FROM 2.67 PERCENT LAST WEEK. THE MOST WIDESPREAD IMPROVEMENTS MADE TO  
THE DROUGHT DEPICTION THIS WEEK WERE OVER THE NORTHWESTERN CONUS. AREAS ACROSS  
THE SOUTHERN AND CENTRAL PLAINS AND THE LOWER AND MIDDLE MISSISSIPPI VALLEY HAD  
THE MOST WIDESPREAD DROUGHT CLASS DEGRADATION.  
 
FORECASTER: MELISSA OU  
 

 
 
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