256  
FXUS21 KWNC 272034  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EDT OCTOBER 27 2017  
 
SYNOPSIS: A SURFACE LOW PRESSURE SYSTEM IS PREDICTED TO DEVELOP OVER THE  
NORTHEAST BY OCT 30, EXITING THE U.S. BY OCT 31. A COLD FRONT IS EXPECTED TO  
SINK SOUTHWARD ACROSS THE U.S. AT THE BEGINNING OF THE PERIOD. A SURFACE LOW IS  
ANTICIPATED TO FORM OVER THE NORTHERN PLAINS BY NOV 1 AND TRACK EASTWARD TO THE  
GREAT LAKES BY NOV 2. MULTIPLE SURFACE HIGHS, ORIGINATING FROM THE HIGH  
LATITUDES OF NORTHWEST CANADA, ARE EXPECTED TO BUILD SOUTH INTO THE CONTINENTAL  
U.S. THROUGH EARLY NOVEMBER. SURFACE HIGH PRESSURE IS FORECAST TO FORM ACROSS  
MUCH OF ALASKA BY THE MIDDLE OF THE 3 TO 7 DAY PERIOD INTO WEEK-2.  
 
HAZARDS  
 
HIGH WINDS ACROSS PORTIONS OF THE NORTHEAST, NEW JERSEY, AND THE GREAT LAKES,  
MON, OCT 30.  
 
HEAVY SNOW ACROSS PORTIONS OF THE GREAT LAKES AND THE UPPER MISSISSIPPI VALLEY,  
MON-TUE, OCT 30-OCT 31.  
 
HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE NORTHERN PLAINS, THE  
MIDDLE MISSISSIPPI VALLEY, AND THE UPPER MISSISSIPPI VALLEY, MON, OCT 30.  
 
MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE SOUTHEAST, MON, OCT 30.  
 
HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN ROCKIES AND THE NORTHERN GREAT  
BASIN, WED-THU, NOV 1-NOV 2.  
 
HEAVY SNOW ACROSS PORTIONS OF THE CASCADES, THU-FRI, NOV 2-NOV 3.  
 
HIGH WINDS ACROSS PARTS OF THE SOUTH COAST OF ALASKA AND THE ALEUTIANS, MON,  
OCT 30.  
 
HIGH SIGNIFICANT WAVE HEIGHTS FOR COASTAL PORTIONS OF THE SOUTH COAST OF ALASKA  
AND THE ALEUTIANS, MON, OCT 30.  
 
HIGH WINDS ACROSS PORTIONS OF THE ALASKA PANHANDLE, THU, NOV 2.  
 
HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN SIERRAS, CASCADES, IDAHO, NORTHERN  
GREAT BASIN, AND NORTHERN ROCKIES, SAT, NOV 4.  
 
HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE CENTRAL ROCKIES, THE  
CENTRAL GREAT BASIN, THE SOUTHERN ROCKIES, THE SOUTHERN PLAINS, AND THE  
SOUTHWEST, SAT-SUN, NOV 4-NOV 5.  
 
HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL PLAINS, THE LOWER MISSISSIPPI VALLEY,  
THE TENNESSEE VALLEY, THE MIDDLE MISSISSIPPI VALLEY, THE SOUTHEAST, THE  
SOUTHERN PLAINS, AND THE OHIO VALLEY, MON-WED, NOV 6-NOV 8.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE NORTHWESTERN  
AND NORTH-CENTRAL CONUS, SAT-THU, NOV 4-NOV 9.  
 
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF MONTANA,  
SUN-WED, NOV 5-NOV 8.  
 
SEVERE DROUGHT ACROSS THE NORTHERN PLAINS, THE NORTHERN ROCKIES, AND HAWAII.  
 
FLOODING POSSIBLE ACROSS PORTIONS OF THE NORTHEAST AND THE GREAT LAKES.  
 
FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE SOUTHEAST.  
 
DETAILED SUMMARY  
 
FOR MONDAY OCTOBER 30 - FRIDAY NOVEMBER 03: A STORM IS FORECAST TO DEVELOP OVER  
THE NORTHEAST BY OCT 30 AND EXIT THE CONUS ON OCT 31. THIS STORM MAY BRING HIGH  
WINDS ACROSS PORTIONS OF THE NORTHEAST, NEW JERSEY, AND THE GREAT LAKES ON OCT  
30. LOCALIZED AREAS MAY EXPERIENCE SUSTAINED WIND SPEEDS REACHING 40 KNOTS OR  
GREATER.  
 
STRONG COLD AIR ADVECTION IS LIKELY TO CAUSE PERIODS OF LAKE-ENHANCED RAIN AND  
SNOW NEXT WEEK DOWNWIND OF LAKES MICHIGAN AND SUPERIOR. THE HEAVIEST  
LAKE-EFFECT SNOW (6 INCHES OR MORE PER 24 HOURS) IS MOST LIKELY DOWNWIND OF  
LAKE SUPERIOR IN NORTHERN WISCONSIN AND THE UPPER PENINSULA OF MICHIGAN ON OCT  
30 AND 31. A TIGHT PRESSURE GRADIENT IS ANTICIPATED OVER THE NORTHERN AND  
CENTRAL PLAINS ASSOCIATED WITH THIS LOW AND SURFACE HIGH PRESSURE OVER THE  
NORTHERN ROCKIES, SUPPORTING HIGH WINDS (25 KNOTS OR GREATER) ACROSS PARTS OF  
THE CENTRAL PLAINS, THE NORTHERN PLAINS, THE MIDDLE MISSISSIPPI VALLEY, AND THE  
UPPER MISSISSIPPI VALLEY OCT 30.  
 
SURFACE HIGH PRESSURE IS EXPECTED TO BUILD SOUTHEAST INTO THE LOWER MISSISSIPPI  
VALLEY AND SOUTHEAST BY OCT 30. A MUCH BELOW-NORMAL TEMPERATURE HAZARD IS  
POSTED ON OCT 30 FOR PARTS OF THE SOUTHEAST WHERE MINIMUM TEMPERATURES ARE  
FORECAST TO AVERAGE MORE THAN 10 DEGREES F BELOW NORMAL AND WHERE THE FIRST  
WIDESPREAD FROST OR LIGHT FREEZE IS EXPECTED.  
 
MODEL SOLUTIONS INDICATE A STRONG COLD FRONT ADVANCING SOUTH ACROSS THE CENTRAL  
U.S. EARLY NEXT WEEK. BEHIND THIS COLD FRONT, HIGH WINDS (GUSTS ABOVE 40 MPH)  
ARE FORECAST ACROSS THE NORTHERN AND CENTRAL PLAINS ON OCT 30.  
 
SURFACE LOW PRESSURE ALONG A COLD FRONT IS ANTICIPATED TO FORM ACROSS THE  
PACIFIC NORTHWEST AND NORTHERN ROCKIES BY NOV 1. THIS PATTERN MAY BRING HEAVY  
SNOW TO PARTS OF THE NORTHERN ROCKIES AND THE NORTHERN GREAT BASIN NOV 1 TO 2  
AND TO THE CASCADES NOV 2 TO 3. SNOW LEVELS IN SOME AREAS ARE EXPECTED TO LOWER  
TO PASS AND VALLEY LEVELS BY NOV 2. LOCALIZED AREAS MAY RECEIVE SEVERAL INCHES  
OF SNOW.  
 
A LOW PRESSURE SYSTEM IS PREDICTED TO DEVELOP OVER THE BERING SEA AT THE  
BEGINNING OF THE PERIOD, BRINGING HIGH WINDS (40 KNOTS OR GREATER) TO PARTS OF  
THE SOUTH COAST OF ALASKA AND THE ALEUTIANS ON OCT 30. HIGH WINDS WITH AN  
ONSHORE COMPONENT MAY SUPPORT SIGNIFICANT WAVE HEIGHTS (30 FEET OR GREATER) FOR  
COASTAL PARTS OF THE SOUTH COAST OF ALASKA AND THE ALEUTIANS ON OCT 30. SURFACE  
HIGH PRESSURE IS EXPECTED TO FORM OVER THE YUKON TERRITORY AND MAINLAND ALASKA,  
WHICH IS EXPECTED TO RESULT IN TAKU WINDS (OFFSHORE GUSTS ABOVE 50 MPH) IN THE  
VICINITY OF JUNEAU, ALASKA ON NOV 2.  
 
FOR SATURDAY NOVEMBER 04 - FRIDAY NOVEMBER 10: A LONGWAVE PATTERN CHANGE IS  
EXPECTED TO BE ONGOING AT THE BEGINNING OF NOVEMBER AS ANOMALOUS RIDGING  
(500-HPA HEIGHTS NEAR 564DM) BECOMES ESTABLISHED ACROSS WESTERN ALASKA AND AN  
UPPER-LEVEL TROUGH RETROGRADES TO WESTERN NORTH AMERICA. THIS PATTERN CHANGE IS  
CONSISTENT WITH THE ENHANCED PHASE OF THE MJO PROPAGATING EAST ACROSS THE  
WESTERN HEMISPHERE DURING THE NEXT TWO WEEKS.  
 
THE EVOLVING LONGWAVE PATTERN SUPPORTS AT LEAST A SLIGHT RISK OF MUCH  
BELOW-NORMAL TEMPERATURES FOR PARTS OF THE NORTHWESTERN AND NORTH-CENTRAL CONUS  
DURING WEEK-2. A MODERATE RISK OF MUCH BELOW-NORMAL TEMPERATURES IS POSTED FOR  
PARTS OF MONTANA, NOV 5 TO 8.  
 
THE AMPLIFYING UPPER-LEVEL TROUGH ALOFT FAVORS MODERATE TO HEAVY SNOW ACROSS  
THE NORTHERN ROCKIES AND THE NORTHERN GREAT BASIN, CASCADES, AND NORTHERN  
SIERRA MOUNTAINS EARLY IN WEEK-2. THE GFS AND ECMWF ENSEMBLE MEANS INDICATE 0.5  
INCHES OR MORE OF LIQUID EQUIVALENT PER 24 HOURS, ACROSS THESE AREAS ON NOV 3  
AND 4. SHALLOW, SUB-FREEZING TEMPERATURES MAY LEAD TO FREEZING RAIN ACROSS THE  
COLUMBIA RIVER GORGE.  
 
THE U.S. DROUGHT MONITOR, VALID ON OCTOBER 24, INDICATES THAT SEVERE TO  
EXCEPTIONAL (D2-D4) DROUGHT COVERS 2.58 PERCENT OF THE CONTINENTAL U.S., WHICH  
IS THE LOWEST COVERAGE SINCE JUNE. DUE TO RECENT RAINFALL, SEVERE TO  
EXCEPTIONAL DROUGHT IS LIMITED TO THE NORTHERN GREAT PLAINS, AND NORTHERN  
ROCKIES AND HAWAII.  
 
FORECASTER: MELISSA OU  
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page