196  
FXUS21 KWNC 021847  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EDT NOVEMBER 02 2017  
 
SYNOPSIS: AT THE BEGINNING OF THE 3-7 DAY PERIOD, A RIDGE OF SURFACE HIGH  
PRESSURE IS FORECAST ALONG THE ATLANTIC COAST STATES, AND A FRONTAL SYSTEM IS  
PREDICTED TO STRETCH FROM THE MIDWESTERN STATES WESTWARD ACROSS THE CENTRAL  
PLAINS, THE CENTRAL ROCKIES, AND CONTINUE WESTWARD TO SOUTHERN CALIFORNIA.  
ANOTHER LOW PRESSURE AREA IS ANTICIPATED TO MOVE ONSHORE IN THE PACIFIC  
NORTHWEST. DURING THE ENSUING FEW DAYS, THE FIRST STORM SYSTEM IS EXPECTED TO  
MOVE ACROSS THE REMAINING AREAS OF THE CENTRAL AND EASTERN CONUS, WITH THE  
EXCEPTION OF CENTRAL AND SOUTHERN FLORIDA. THE SECOND SYSTEM RAPIDLY WEAKENS  
OVER THE PACIFIC NORTHWEST, ONLY TO BE FOLLOWED BY ANOTHER PACIFIC STORM  
SYSTEM. DURING WEEK 2, FAST WESTERLY FLOW ALOFT IS PREDICTED ACROSS THE CONUS,  
WITH MID-LEVEL LOW PRESSURE CENTERED NEAR THE PACIFIC NORTHWEST COAST. IN  
ALASKA, MOST OF THE OUTLOOK PERIOD IS FORECAST TO BE DOMINATED BY STRONG  
NORTHERLY FLOW ALOFT AND MINIMAL STORM ACTIVITY, EXCEPT FOR PERSISTENT SURFACE  
LOW PRESSURE IN THE VICINITY OF THE PANHANDLE.  
 
HAZARDS  
 
SEVERE WEATHER FROM ILLINOIS TO THE SHORES OF LAKE ERIE, SUN, NOV 5.  
 
HEAVY RAIN FOR PORTIONS OF THE SOUTHERN GREAT LAKES REGION, SUN-MON, NOV 5-6.  
 
HEAVY RAIN NEAR THE CONFLUENCE AREA OF KENTUCKY, VIRGINIA, AND WEST VIRGINIA,  
TUE-WED, NOV 7-8.  
 
HEAVY SNOW IN WESTERN COLORADO, SUN-MON, NOV 5-6.  
 
MUCH BELOW-NORMAL TEMPERATURES FROM EASTERN WASHINGTON STATE TO NORTH DAKOTA,  
SUN-TUE, NOV 5-7.  
 
MUCH ABOVE-NORMAL TEMPERATURES FOR THE SOUTHERN PLAINS, SUN-MON, NOV 5-6.  
 
FLOODING OCCURRING OR IMMINENT ACROSS PART OF CENTRAL FLORIDA.  
 
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FROM WASHINGTON STATE EASTWARD  
ACROSS THE NORTHERN PLAINS TO UPPER MICHIGAN, FRI-TUE, NOV 10-14.  
 
SEVERE DROUGHT ACROSS THE NORTHERN PLAINS, THE NORTHERN ROCKIES, PARTS OF  
ARIZONA AND TEXAS, AND HAWAII.  
 
DETAILED SUMMARY  
 
FOR SUNDAY NOVEMBER 05 - THURSDAY NOVEMBER 09: AS AN OCCLUDED FRONTAL SYSTEM  
APPROACHES THE MIDWESTERN STATES ON NOV 5, IT IS EXPECTED TO TRIGGER SEVERE  
WEATHER ACROSS THE EASTERN CORN BELT AND SOUTHERN GREAT LAKES REGION. THE STORM  
PREDICTION CENTER NOTES THAT COLD AIR ALOFT, A CAPPING INVERSION OVER THE WARM  
SECTOR, AND VERTICAL WIND SHEAR ARE ALL EXPECTED TO PLAY A ROLE IN THE  
GENERATION OF LARGE HAIL, DAMAGING WINDS, AND EVEN A FEW TORNADOES, WITH  
SUPERCELL THUNDERSTORMS EXPECTED TO BE THE DOMINANT STORM MODE.  
 
TWO AREAS OF HEAVY RAIN (1.5-2.0 INCHES) ARE ANTICIPATED WITH THE PASSAGE OF  
THE OCCLUDED FRONTAL SYSTEM. THE FIRST AREA INCLUDES MUCH OF THE SOUTHERN GREAT  
LAKES REGION (NOV 5-6), AND THE SECOND AREA INCLUDES PORTIONS OF THE  
SOUTH-CENTRAL APPALACHIANS AND ENVIRONS (NOV 7-8).  
 
ANOMALOUSLY COLD AIR FROM CANADA IS ANTICIPATED TO MOVE ACROSS THE NORTHERN  
ROCKIES AND NORTHERN PLAINS (NOV 5-7), IN THE WAKE OF THE OCCLUDED FRONTAL  
SYSTEM. MINIMUM TEMPERATURES ARE FORECAST TO RANGE BETWEEN 12-20 DEGREES F  
BELOW NORMAL. MEANWHILE, ACROSS THE SOUTHERN PLAINS IN ADVANCE OF THE STORM  
SYSTEM'S COLD FRONT, DAYTIME TEMPERATURES ARE PREDICTED TO REACH THE MID AND  
UPPER 80'S (16-20 DEGREES ABOVE NORMAL), WHICH WOULD BE ENOUGH IN SOME SPOTS TO  
BREAK DAILY TEMPERATURE RECORDS.  
 
ON NOV 5-6, HEAVY SNOW (6 INCHES OR MORE IN A 24-HOUR PERIOD) IS ANTICIPATED  
OVER THE HIGHER ELEVATIONS OF WESTERN COLORADO, ASSOCIATED WITH A NEARBY COLD  
FRONT AND MID-LEVEL TROUGH.  
 
ON NOV 7-8, ANOTHER CYCLONIC SYSTEM OVER THE EASTERN GULF OF ALASKA IS EXPECTED  
TO BRING HEAVY PRECIPITATION (2-3 INCHES) TO VANCOUVER ISLAND, CANADA, WITH  
SOME OF THIS MOISTURE MAKING IT INTO WESTERN WASHINGTON STATE. HOWEVER, IT  
APPEARS THAT PRECIPITATION AMOUNTS WILL NOT BE ANYWHERE NEAR ENOUGH TO JUSTIFY  
A HAZARD IN WESTERN WASHINGTON.  
 
PROLONGED FLOODING CONTINUES ALONG THE ST. JOHNS RIVER IN CENTRAL FLORIDA.  
 
LATE IN THE 3-7 DAY PERIOD, THE 0Z ECMWF PREDICTED THE POSSIBILITY OF A  
SIGNIFICANT WINTER STORM FOR THE INTERIOR NORTHEAST. HOWEVER, THE 12Z ECMWF AND  
THE LATEST GFS RUNS PREDICTED A MUCH FLATTER SHORTWAVE TROUGH AND NO MAJOR  
STORM SYSTEM. MODEL RUNS WILL BE CONSULTED TOMORROW TO SEE IF THERE IS ANY  
MERIT TO THIS PREDICTION OF A POTENTIALLY SIGNIFICANT WINTER STORM.  
 
STRONG HIGH PRESSURE PREDICTED ACROSS THE YUKON IS PREDICTED TO LEAD TO STRONG  
EASTERLY TAKU WINDS THROUGH THE MOUNTAIN PASSES OF THE ALASKA PANHANDLE ON NOV  
7. WIND SPEEDS OF AT LEAST 40 MPH ARE EXPECTED, BUT DUE TO THE RELATIVELY  
LOCALIZED NATURE OF THE WIND THREAT, NO HAZARD WAS PLACED ON THE MAP TODAY.  
 
FOR FRIDAY NOVEMBER 10 - THURSDAY NOVEMBER 16: DURING WEEK-2, ANOMALOUS 500-HPA  
TROUGHING IS FORECAST ONLY OVER THE PACIFIC NORTHWEST, WITH NEAR TO  
ABOVE-NORMAL 500-HPA HEIGHTS OVER THE REMAINDER OF THE CONUS. THE ONLY HAZARDS  
INDICATED DURING THE WEEK-2 PERIOD INCLUDE PERSISTENT, LONG-TERM DROUGHT  
PRIMARILY OVER THE NORTHERN PLAINS, AND A SLIGHT RISK OF MUCH BELOW-NORMAL  
TEMPERATURES DURING NOV 10-14 FROM WASHINGTON STATE EASTWARD ACROSS THE  
NORTHERN TIER OF STATES TO UPPER MICHIGAN. THE SLIGHT RISK AREA DENOTES WHERE  
THE GEFS PROBABILISTIC EXTREMES TOOL INDICATES AT LEAST A 20% CHANCE OF MINIMUM  
TEMPERATURES BEING BELOW THE 15TH CLIMATOLOGICAL PERCENTILE.  
 
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: ANTHONY ARTUSA  
 

 
 
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