063  
FXUS21 KWNC 011907  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EDT NOVEMBER 01 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 AN EAST-TO-WEST  
FRONTAL BOUNDARY IS GENERALLY EXPECTED FROM THE CAROLINAS AND OHIO VALLEY  
WESTWARD ACROSS THE MIDDLE MISSISSIPPI VALLEY, SOUTH-CENTRAL PLAINS, AND  
NORTH-CENTRAL ROCKIES, TO NORTHERN CALIFORNIA. OVER THE NEXT FEW DAYS, A SURGE  
OF CANADIAN HIGH PRESSURE IS EXPECTED TO DRIVE COLDER AIR SOUTH ACROSS THE  
NORTHERN CONUS, EAST OF THE CONTINENTAL DIVIDE. BY DAY 7, THE LEADING EDGE OF  
THIS POLAR AIR IS ANTICIPATED TO BE LOCATED FROM ABOUT THE RIO GRANDE VALLEY  
EASTWARD ACROSS THE SOUTHERN PLAINS AND THE GULF COAST STATES. 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.  
 
HAZARDS  
 
SEVERE WEATHER FROM ILLINOIS TO LOWER MICHIGAN, SUN, NOV 5.  
 
HEAVY RAIN FOR PORTIONS OF LOWER MICHIGAN AND INDIANA, SAT-SUN, NOV 4-5.  
 
HEAVY SNOW IN THE SIERRA RANGE, SAT-SUN, NOV 4-5.  
 
HEAVY PRECIPITATION IN PORTIONS OF WESTERN WASHINGTON STATE, TUE, NOV 7.  
 
MUCH BELOW-NORMAL TEMPERATURES FROM NORTHERN PORTIONS OF THE INTERMOUNTAIN  
REGION TO THE NORTHERN HIGH PLAINS, SUN-WED, NOV 5-8.  
 
PERIODS OF STRONG WINDS OVER THE ALASKA PANHANDLE, MON-WED, NOV 6-8.  
 
FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF FLORIDA.  
 
MODERATE RISK OF MUCH BELOW-NORMAL TEMPERATURES FROM WASHINGTON STATE TO NORTH  
DAKOTA, THU-SAT, NOV 9-11.  
 
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FROM WASHINGTON STATE EASTWARD TO  
THE UPPER MISSISSIPPI VALLEY, THU-MON, NOV 9-13.  
 
SEVERE DROUGHT ACROSS THE NORTHERN PLAINS, THE NORTHERN ROCKIES, AND HAWAII.  
 
DETAILED SUMMARY  
 
FOR SATURDAY NOVEMBER 04 - WEDNESDAY NOVEMBER 08: A COLD FRONT APPROACHING THE  
MIDWESTERN STATES IS EXPECTED TO TRIGGER SEVERE WEATHER ACROSS THE EASTERN CORN  
BELT AND SOUTHWESTERN GREAT LAKES REGION ON NOV 5. LARGE HAIL AND DAMAGING  
WINDS ARE LIKELY TO BE THE MAIN HAZARDS ASSOCIATED WITH THESE THUNDERSTORMS. A  
SMALLER-SCALE AREA OF HEAVY RAIN (1.5-2.0 INCHES) IS ANTICIPATED OVER PORTIONS  
OF LOWER MICHIGAN AND INDIANA FROM NOV 4-5.  
 
ANOMALOUS MID-LEVEL TROUGHING IS FORECAST TO BE ESTABLISHED OVER THE PACIFIC  
NORTHWEST AT THE OUTSET OF THE FORECAST PERIOD. SURFACE LOW PRESSURE IS  
FORECAST DOWNSTREAM OF THE TROUGH AND TO PUSH EASTWARD INTO THE NORTHERN PLAINS  
BY THE WEEKEND BEFORE LIFTING TOWARDS HUDSON BAY. THIS SETUP FAVORS THE FLOW OF  
MOISTURE OFF THE PACIFIC AND INTO THE WEST, THOUGH TODAY'S MODEL RUNS DO NOT  
LOOK AS WET AS YESTERDAY'S RUNS DID. FOR THIS REGION, THE ONLY PRECIPITATION  
HAZARD NOTED DURING THE FIRST TWO DAYS OF THE PERIOD IS FOR HEAVY SNOW (6  
INCHES OR MORE IN 24 HOURS) IN THE SIERRA NEVADA RANGE. AS THE SURFACE LOW  
PRESSURE SYSTEM ASSOCIATED WITH THIS TROUGH LIFTS NORTHWARD INTO CANADA IT IS  
FORECAST TO PULL DOWN ANOMALOUSLY COLD AIR FROM CANADA ACROSS THE NORTHERN  
ROCKIES AND THE NORTHERN PLAINS (NOV 5-8). MINIMUM TEMPERATURES ARE FORECAST TO  
RANGE BETWEEN 12-24 DEGREES F BELOW NORMAL.  
 
ANOTHER DISTURBANCE IS FORECAST TO APPROACH THE PACIFIC NORTHWEST AT THE TAIL  
END OF THE 3-7 DAY PERIOD. MODEL GUIDANCE BRINGS MOST OF THE PRECIPITATION (5  
INCHES, LIQUID EQUIVALENT) INTO VANCOUVER ISLAND, BRITISH COLUMBIA, ON NOV 6-7,  
WITH LIGHTER BUT STILL SIGNIFICANT PRECIPITATION AMOUNTS EXPECTED TO PUSH INTO  
WESTERN WASHINGTON STATE ON NOV 7. SIX OR MORE INCHES OF SNOW IS POSSIBLE IN  
THE HIGHER TERRAIN OF THE CASCADES, WHILE RAINFALL AT LOWER ELEVATIONS IS  
FORECAST TO BE IN THE 1-2 INCH RANGE.  
 
ANOMALOUS RIDGING IS FORECAST TO BUILD ACROSS TEXAS AND THE GULF STATES  
THROUGHOUT DAYS 3-7, WITH THE WEATHER PREDICTION CENTER FORECASTING DAILY HIGH  
TEMPERATURE ANOMALIES EXCEEDING 20 DEGREES F ABOVE NORMAL FOR PORTIONS OF THE  
SOUTHERN PLAINS. THIS WOULD BRING DAILY HIGH TEMPERATURES INTO THE MID- TO  
UPPER-80S, WHICH COULD BREAK SOME HIGH TEMPERATURE RECORDS ACROSS THIS REGION.  
 
PROLONGED FLOODING CONTINUES ALONG THE ST. JOHNS RIVER IN CENTRAL FLORIDA.  
 
STRONG HIGH PRESSURE PREDICTED ACROSS THE YUKON IS PREDICTED TO LEAD TO STRONG  
EASTERLY TAKU WINDS THROUGH THE MOUNTAIN PASSES OF THE ALASKA PANHANDLE BETWEEN  
NOV 6-8. WIND SPEEDS OF AT LEAST 40 MPH ARE EXPECTED.  
 
FOR THURSDAY NOVEMBER 09 - WEDNESDAY NOVEMBER 15: DURING WEEK-2, ANOMALOUS  
500-HPA TROUGHING IS FORECAST TO DOMINATE THE PACIFIC NORTHWEST AND NORTHERN  
INTERMOUNTAIN REGION. THIS IS ANTICIPATED TO GIVE RISE TO A SLIGHT RISK OF MUCH  
BELOW-NORMAL TEMPERATURES DURING NOV 9-13 FROM WASHINGTON STATE EASTWARD ACROSS  
THE NORTHERN TIER OF STATES TO THE UPPER MISSISSIPPI VALLEY. A MODERATE RISK OF  
MUCH BELOW-NORMAL TEMPERATURES IS PREDICTED WITHIN THE SLIGHT RISK AREA, FROM  
NOV 9-11. THE SLIGHT (MODERATE) RISK AREAS DENOTE WHERE THE GEFS PROBABILISTIC  
EXTREMES TOOL INDICATES AT LEAST A 20% (40%) CHANCE OF MINIMUM TEMPERATURES  
BEING BELOW THE 15TH CLIMATOLOGICAL PERCENTILE.  
 
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: ANTHONY ARTUSA  
 

 
 
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