709  
FXUS21 KWNC 062031  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST MARCH 06 2018  
 
SYNOPSIS: SURFACE LOW PRESSURE AND ITS ASSOCIATED FRONTAL SYSTEM WILL CROSS THE  
NORTHWESTERN U.S. MAR 9, FOLLOWED BY ANOTHER DEEPER AREA OF SURFACE LOW  
PRESSURE MAR 12-13. SURFACE LOW PRESSURE IS FORECAST TO DEVELOP OVER THE  
SOUTHERN PLAINS MAR 9 AND MOVE EAST/NORTHEASTWARD TO OFF THE MID-ATLANTIC COAST  
MAR 12. DEEP SURFACE LOW PRESSURE OVER THE SOUTH COAST OF ALASKA MAR 9 IS  
FORECAST TO MOVE SLOWLY SOUTHEASTWARD. DURING WEEK-2, AREAS OF MID-LEVEL LOW  
PRESSURE ARE ANTICIPATED TO BE OVER THE FAR WESTERN ATLANTIC, ALONG THE U.S.  
WEST COAST, AND OVER ALASKA, WHILE MID-LEVEL HIGH PRESSURE IS EXPECTED OVER THE  
CENTRAL PORTION OF THE LOWER 48 STATES.  
 
HAZARDS  
 
HEAVY SNOW FOR PARTS OF THE BITTERROOTS, FRI, MAR 9.  
 
HEAVY SNOW FOR PARTS OF THE NORTHERN ROCKIES, FRI, MAR 9.  
 
HEAVY RAIN FOR PARTS OF THE LOWER MISSISSIPPI AND TENNESSEE VALLEYS, SAT, MAR  
10.  
 
HEAVY RAIN FOR PARTS OF THE MID-ATLANTIC, SUN, MAR 11.  
 
HEAVY SNOW FOR PARTS OF THE CENTRAL APPALACHIANS, SUN, MAR 11.  
 
HEAVY SNOW FOR PARTS OF THE SIERRAS AND THE COASTAL RANGE IN CALIFORNIA, TUE,  
MAR 13.  
 
HIGH WINDS FOR PARTS OF THE ALEUTIANS, ALASKA PENINSULA, SOUTHERN AND WESTERN  
COASTAL MAINLAND ALASKA, AND THE ALASKA PANHANDLE, FRI-SAT, MAR 9-10.  
 
HIGH SIGNIFICANT WAVE HEIGHTS FOR PARTS OF THE ALEUTIANS, ALASKA PENINSULA, AND  
SOUTHERN COASTAL MAINLAND ALASKA, FRI-SAT, MAR 9-10.  
 
FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE SOUTHERN PLAINS, LOWER  
AND MIDDLE MISSISSIPPI VALLEYS, THE OHIO AND TENNESSEE VALLEYS, AND THE GREAT  
LAKES.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE SOUTHEAST,  
CENTRAL AND SOUTHERN APPALACHIANS, LOWER MISSISSIPPI AND TENNESSEE VALLEYS, AND  
MID-ATLANTIC, WED-THU, MAR 14-15.  
 
MODERATE RISK FOR MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF FLORIDA AND  
EXTREME SOUTHERN GEORGIA, WED, MAR 14.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE WESTERN  
CONUS, THU-TUE, MAR 15-20.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF WESTERN MAINLAND  
ALASKA AND THE ALASKA PENINSULA, FRI-TUE, MAR 16-20.  
 
SLIGHT RISK OF HEAVY PRECIPITATIONS FOR PART OF THE TENNESSEE AND OHIO VALLEYS,  
AND GREAT LAKES, FRI-SUN, MAR 16-18.  
 
SLIGHT RISK FOR HEAVY PRECIPITATION FOR PARTS OF THE WESTERN CONUS, WED-FRI,  
MAR 14-16.  
 
MODERATE RISK FOR HEAVY PRECIPITATION FOR PARTS OF THE SOUTHWESTERN CONUS,  
WED-FRI, MAR 14-16.  
 
HIGH RISK FOR HEAVY PRECIPITATION FOR PARTS OF THE SOUTHWESTERN CONUS, WED-FRI,  
MAR 14-16.  
 
SEVERE DROUGHT ACROSS THE CENTRAL PLAINS, THE CENTRAL ROCKIES, THE CENTRAL  
GREAT BASIN, THE NORTHERN PLAINS, THE SOUTHERN ROCKIES, CALIFORNIA, THE  
SOUTHERN PLAINS, AND THE SOUTHWEST.  
 
DETAILED SUMMARY  
 
FOR FRIDAY MARCH 09 - TUESDAY MARCH 13: COLD HIGH PRESSURE IS FORECAST OVER THE  
SOUTHEASTERN CONUS MAR 9. BELOW NORMAL TEMPERATURES ARE ANTICIPATED FOR THE  
REGION BUT HAZARDOUS CONDITIONS ARE NOT EXPECTED.  
 
A PAIR OF CYCLONES ARE FORECAST TO AFFECT THE WESTERN CONUS DURING THE PERIOD.  
THE FIRST SYSTEM IS EXPECTED TO CROSS THE NORTHWESTERN U.S. MAR 9. HEAVY SNOW  
(AMOUNTS IN EXCESS OF 4 INCHES IN 24 HOURS) IS PREDICTED FOR PORTIONS OF THE  
BITTERROOTS AND NORTHERN ROCKIES. ANOTHER CYCLONE IS FORECAST TO APPROACH THE  
PACIFIC NORTHWEST MAR 12-13 LEADING TO HEAVY SNOW (AMOUNTS IN EXCESS OF 6  
INCHES IN 24 HOURS) FOR PARTS OF THE COASTAL RANGE AND SIERRAS IN CALIFORNIA  
MAR 13.  
 
LOW PRESSURE IS PREDICTED TO DEVELOP OVER THE SOUTHERN PLAINS MAR 9 AND MOVE  
EAST/NORTHEASTWARD TO OFF THE MID-ATLANTIC COAST MAR 12. HEAVY RAIN (AMOUNTS IN  
EXCESS OF 1 INCH IN 24 HOURS) IS ANTICIPATED FOR PARTS OF THE LOWER MISSISSIPPI  
AND TENNESSEE VALLEYS ON MAR 10, AND PARTS OF THE MID-ATLANTIC MAR 11. HEAVY  
SNOW (AMOUNTS IN EXCESS OF 4 INCHES IN 24 HOURS) IS FORECAST FOR PARTS OF THE  
CENTRAL APPALACHIANS MAR 11.  
 
ANTECEDENT PRECIPITATION AND THE PROSPECT OF ADDITIONAL PRECIPITATION LEADS TO  
OCCURRING OR IMMINENT FLOODING ACROSS PORTIONS OF THE SOUTHERN PLAINS, LOWER  
AND MIDDLE MISSISSIPPI VALLEYS, THE OHIO AND TENNESSEE VALLEYS, AND THE GREAT  
LAKES.  
 
DEEP LOW PRESSURE MOVING FROM THE SOUTH COAST OF MAINLAND ALASKA TO THE GULF OF  
ALASKA LEADS TO HIGH WINDS (SPEEDS IN EXCESS OF 40 KNOTS) FOR THE ALEUTIANS,  
ALASKA PENINSULA, SOUTHERN AND WESTERN COASTAL MAINLAND ALASKA, AND THE ALASKA  
PANHANDLE, AND HIGH SIGNIFICANT WAVE HEIGHTS (HEIGHTS IN EXCESS OF 24 FEET) FOR  
PARTS OF THE ALEUTIANS, ALASKA PENINSULA, AND SOUTHERN COASTAL MAINLAND ALASKA  
MAR 8-10.  
 
FOR WEDNESDAY MARCH 14 - TUESDAY MARCH 20: DURING WEEK-2, MID-LEVEL TROUGHS ARE  
ANTICIPATED TO BE OVER THE FAR WESTERN ATLANTIC, ALONG THE U.S. WEST COAST, AND  
OVER ALASKA, WHILE A MID-LEVEL RIDGE IS FORECAST OVER THE CENTRAL CONUS. THIS  
CIRCULATION PATTERN LEADS TO A SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES  
FOR PORTIONS OF THE SOUTHEAST, CENTRAL AND SOUTHERN APPALACHIANS, AND  
MID-ATLANTIC MAR 14-15, A MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR  
MUCH OF FLORIDA AND EXTREME SOUTHERN PORTIONS OF GEORGIA MAR 14, A SLIGHT RISK  
OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE WESTERN CONUS MAR 15-20,  
AND A SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF WESTERN  
MAINLAND ALASKA AND THE ALASKA PENINSULA MAR 16-20.  
 
THE TROUGH FORECAST ALONG THE WEST COAST LEADS TO A SLIGHT RISK FOR HEAVY  
PRECIPITATION FOR PARTS OF THE WESTERN CONUS MAR 14-16, A MODERATE RISK FOR  
HEAVY PRECIPITATION FOR PARTS OF THE SOUTHWESTERN CONUS MAR 14-16, AND A HIGH  
RISK FOR HEAVY PRECIPITATION FOR PARTS OF THE SOUTHWESTERN CONUS MAR 14-16.  
 
MOIST INFLOW AROUND THE REAR SIDE OF SURFACE HIGH PRESSURE FORECAST OVER THE  
EASTERN U.S. LEADS TO A SLIGHT RISK OF HEAVY PRECIPITATIONS FOR PART OF THE  
TENNESSEE AND OHIO VALLEYS AND GREAT LAKES MAR 16-18.  
 
THE U.S. DROUGHT MONITOR, VALID ON FEB 27, 2018 INDICATES A DECREASE IN THE  
COVERAGE OF SEVERE TO EXCEPTIONAL DROUGHT (D2-D4) FROM 17.76% LAST WEEK TO  
14.31% THIS WEEK. A FEW OF THE MORE SUBSTANTIAL REVISIONS MADE TO THE MAP THIS  
WEEK INCLUDE A DECREASE IN THE D1 COVERAGE OVER PENNSYLVANIA AND A DECREASE IN  
THE D2 COVERAGE OVER OKLAHOMA AND ARKANSAS.  
 
FORECASTER: RANDY SCHECHTER  
 

 
 
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