874  
FXUS21 KWNC 062137  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST NOVEMBER 06 2017  
 
SYNOPSIS: A LOW-PRESSURE SYSTEM IS FORECAST TO DEEPEN NEAR THE NORTHEAST LATER  
THIS WEEK, WITH HIGH PRESSURE BUILDING IN BEHIND IT. THIS HIGH-PRESSURE SYSTEM  
IS FORECAST TO SLIDE FROM THE NORTHERN GREAT PLAINS TO THE NORTHEAST BY THE  
BEGINNING OF NEXT WEEKEND. MULTIPLE LOW-PRESSURE SYSTEMS ARE FORECAST TO IMPACT  
THE PACIFIC NORTHWEST, INCLUDING INTO THE EARLY PORTION OF WEEK-2. A STRONG  
LOW-PRESSURE SYSTEM IS FORECAST OVER NORTHWESTERN ALASKA, BEFORE MOVING  
SOUTHWARD AND MERGING WITH A PERSISTENT AREA OF LOW-PRESSURE NEAR WESTERN  
CANADA. A COLDER PATTERN IS LIKELY OVER EASTERN ALASKA DURING WEEK-2.  
 
HAZARDS  
 
HEAVY RAIN AND SNOW (HIGHER ELEVATIONS) ACROSS PORTIONS OF CALIFORNIA AND THE  
PACIFIC NORTHWEST, THU, NOV 9.  
 
HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN ROCKIES, THU-FRI, NOV 9-NOV 10.  
 
HEAVY SNOW ACROSS PORTIONS OF WYOMING AND SOUTHWEST MONTANA, FRI, NOV 10.  
 
HEAVY PRECIPITATION ACROSS PORTIONS OF CALIFORNIA, THE PACIFIC NORTHWEST, THE  
NORTHERN ROCKIES, AND THE NORTHERN GREAT BASIN, SUN-MON, NOV 12-NOV 13.  
 
HIGH WINDS ACROSS PORTIONS OF THE NORTHEAST AND THE GREAT LAKES, FRI, NOV 10.  
 
MUCH BELOW NORMAL TEMPERATURES FROM THE NORTHERN ROCKIES TO THE GREAT LAKES,  
NORTHEAST AND MID-ATLANTIC, THU-SAT, NOV 9-NOV 11.  
 
HIGH WINDS ACROSS PORTIONS OF MAINLAND ALASKA, SUN, NOV 12.  
 
HEAVY PRECIPITATION ACROSS PORTIONS OF THE PACIFIC NORTHWEST, THE NORTHERN  
ROCKIES, AND THE NORTHERN GREAT BASIN, TUE-WED, NOV 14-NOV 15.  
 
FLOODING POSSIBLE ACROSS PORTIONS OF WESTERN NEW YORK AND THE OHIO VALLEY.  
 
FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF FLORIDA.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE ALASKA  
PANHANDLE AND MAINLAND ALASKA, TUE-MON, NOV 14-NOV 20.  
 
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE ALASKA  
PANHANDLE AND MAINLAND ALASKA, TUE-THU, NOV 14-NOV 16.  
 
HIGH RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF MAINLAND ALASKA,  
TUE-WED, NOV 14-NOV 15.  
 
SEVERE DROUGHT ACROSS HAWAII, THE SOUTHERN PLAINS, THE NORTHERN PLAINS, THE  
NORTHERN ROCKIES, AND THE SOUTHWEST.  
 
DETAILED SUMMARY  
 
FOR THURSDAY NOVEMBER 09 - MONDAY NOVEMBER 13: A LOW-PRESSURE SYSTEM IS  
FORECAST TO INTENSIFY OVER SOUTHEASTERN CANADA DURING THE WEEKEND, WITH THE  
ASSOCIATED COLD FRONT PUSHING SOUTHWARD TO THE GULF OF MEXICO. HIGH WINDS  
(GREAT THAN 35 KNOTS OVER THE GREAT LAKES, AND IN EXCESS OF 40 MPH OVER LAND,  
WITH HIGHER WINDS OVER ELEVATED AND EXPOSED AREAS) ARE LIKELY BEHIND THE FRONT.  
THOSE WINDS SIGNAL THE ARRIVAL OF COLDER AIR, WITH TEMPERATURES 12-24 DEG F  
BELOW NORMAL OVER THE GREAT PLAINS. SOME MODERATION IS LIKELY AS THE COLDER AIR  
SLIDES FURTHER EAST, BUT AREAS IN THE CAROLINAS TO THE MID-ATLANTIC AND LONG  
ISLAND COULD SEE THEIR FIRST FREEZE OF THE YEAR. THE COLD AIR AND NORTHWEST  
WINDS SHOULD SUPPORT LAKE ENHANCED SNOWFALL THURSDAY, NOV 9.  
 
AN ACTIVE PERIOD IS FORECAST FOR THE NORTHWEST QUADRANT OF THE COUNTRY. HEAVY  
RAINS (3 INCHES WITH LOCALLY HIGHER AMOUNTS) WITH SNOW AT HIGHER ELEVATIONS.  
RIVERS ARE LIKELY TO RISE QUICKLY AS THIS SYSTEM SHOULD HAVE A GOOD FEED OF  
MOISTURE. AS THE MOISTURE MOVES INLAND, HEAVY SNOWS AND HIGHER WINDS (THOUGH  
THE WINDS ARE LIKELY TO BE CONTAINED TO HIGHER ELEVATIONS) ARE FORECAST OVER  
IDAHO AND IN THE VICINITY OF YELLOWSTONE NATIONAL PARK. MODEL FORECASTS SHOW A  
BREAK IN THE ACTIVITY SATURDAY, WITH ANOTHER SYSTEM MOVING INTO THE AREA ON  
SUNDAY AND LINGERING HEAVY PRECIPITATION IMPACTS INTO WEDNESDAY OF NEXT WEEK.  
THE ECMWF DEPICTS LESS OF A BREAK IN STORMINESS ON SATURDAY, WITH A MORE  
PERSISTENTLY WET PATTERN.  
 
A LOW-PRESSURE SYSTEM IS FORECAST TO DEEPEN OVER NORTHWESTERN ALASKA, BRINGING  
HIGH WINDS (IN EXCESS OF 35MPH) TO THE WESTERN COAST OF ALASKA. UNCERTAINTY  
ABOUT THE EXACT MAGNITUDE OF THE WINDSPEEDS IS ELEVATED AS THE ECMWF RUNS ARE  
LESS BULLISH. COASTAL FLOODING IS POSSIBLE, THOUGH THE UNCERTAINTY IN THE FETCH  
IS TOO HIGH, AT THIS TIME, TO DEPICT THAT HAZARD.  
 
FOR TUESDAY NOVEMBER 14 - MONDAY NOVEMBER 20: DURING WEEK-2, A COLD PATTERN IS  
FORECAST FOR SOUTHEASTERN ALASKA, INCLUDING THE PANHANDLE. A MODERATE RISK OF  
MUCH BELOW NORMAL TEMPERATURES IS INDICATED FOR MUCH OF SOUTHERN ALASKA FOR  
DAYS 8-11, WITH A HIGH RISK FOR SOUTH COASTAL ALASKA DURING DAY 8. THE HIGH  
RISK, AS DEPICTED ON THE MAP, IS ASSOCIATED WITH A 20% CHANCE OF TEMPERATURES  
REACHING THE LOWEST 5TH PERCENTILE AND NEARLY A 60 PERCENT CHANCE OF  
TEMPERATURES BEING IN THE LOWETS 15TH PERCENTILE. WHILE TEMPERATURES ARE LIKELY  
TO BE COLDER THAN AVERAGE, RECORDS IN SOME INLAND AREAS APPROACH MINUS 40 DEG  
F, AND THE CURRENT MODEL OUTPUTS INDICATE THOSE ARE NOT LIKELY TO BE CHALLENGED.  
 
THE OVERALL CIRCULATION PATTERN FOR THE WESTERN CONUS FAVORS HIGH PRESSURE OVER  
THE GREAT BASIN. SUCH A PATTERN WOULD SUPPORT ENHANCED ODDS FOR OFFSHORE FLOW  
(SANTA ANA WINDS) FOR MUCH OF CENTRAL AND SOUTHERN CALIFORNIA. THE THREAT FOR  
HIGH WINDS AND ENHANCED FIRE DANGER WILL BE MONITORED.  
 
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: MATTHEW ROSENCRANS  
 

 
 
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