641  
FXUS21 KWNC 132112  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST FEBRUARY 13 2018  
 
SYNOPSIS: A COLD FRONT STRETCHING FROM THE NORTHEAST TO THE SOUTHERN PLAINS IS  
FORECAST TO MIGRATE SOUTHEASTWARD ACROSS THE EASTERN HALF OF THE LOWER 48  
STATES DURING THE 3 TO 7 DAY PERIOD. BY THE MIDDLE OF THE 3 TO 7 DAY PERIOD, A  
COLD FRONT IS PREDICTED TO ENTER THE NORTHERN TIER OF THE CONTIGUOUS U.S. FROM  
CANADA AND SINK SOUTHWARD ACROSS THE COUNTRY. THIS FRONT IS ANTICIPATED TO  
STRETCH FROM THE NORTHEAST TO THE SOUTHERN PLAINS BY THE END OF WEEK-1 AND  
REMAIN FAIRLY STATIONARY THROUGHOUT WEEK-2. A SERIES OF SURFACE LOWS IS  
PREDICTED TO FORM OVER THE BERING SEA AND GULF OF ALASKA DURING THE 3 TO 7 DAY  
AND WEEK-2 PERIOD, WHILE SURFACE HIGH PRESSURE IS ANTICIPATED TO BUILD ACROSS  
MUCH OF MAINLAND ALASKA DURING THE SAME PERIOD.  
 
HAZARDS  
 
HEAVY RAIN ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY, THE TENNESSEE  
VALLEY, THE SOUTHERN APPALACHIANS, THE SOUTHERN PLAINS, AND THE OHIO VALLEY,  
FRI-SAT, FEB 16-FEB 17.  
 
HEAVY RAIN ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY, THE CENTRAL  
APPALACHIANS, THE TENNESSEE VALLEY, THE GREAT LAKES, THE SOUTHERN APPALACHIANS,  
THE SOUTHEAST, THE SOUTHERN PLAINS, AND THE OHIO VALLEY, MON-TUE, FEB 19-FEB 20.  
 
HEAVY SNOW ACROSS PORTIONS OF THE CASCADES, FRI-SUN, FEB 16-FEB 18.  
 
HEAVY SNOW ACROSS THE NORTHERN GREAT BASIN AND THE NORTHERN ROCKIES, FRI-SUN,  
FEB 16-FEB 18.  
 
HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE NORTHERN PLAINS, THE  
NORTHERN ROCKIES, THE CENTRAL ROCKIES, AND THE NORTHERN GREAT BASIN, SAT-SUN,  
FEB 17-FEB 18.  
 
MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE NORTHERN PLAINS AND THE  
NORTHERN ROCKIES, FRI, FEB 16 AND MON-TUE, FEB 19-FEB 20.  
 
HIGH WINDS ACROSS COASTAL PORTIONS OF CENTRAL CALIFORNIA, TUE, FEB 20.  
 
MUCH ABOVE NORMAL TEMPERATURES ACROSS PORTIONS OF THE NORTH SLOPE REGION IN  
ALASKA, SUN-TUE, FEB 18-FEB 20.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE WESTERN AND  
NORTH-CENTRAL HALF OF THE CONUS, WED-TUE, FEB 21-FEB 27.  
 
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE WESTERN AND  
NORTH-CENTRAL HALF OF THE CONUS, WED-FRI, FEB 21-FEB 23.  
 
HIGH RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE PACIFIC  
NORTHWEST, THE NORTHERN ROCKIES, THE NORTHERN GREAT BASIN, AND THE NORTHERN  
PLAINS, WED-THU, FEB 21-FEB 22.  
 
SLIGHT RISK OF MUCH ABOVE NORMAL TEMPERATURES FOR PORTIONS OF MAINLAND ALASKA  
AND THE ALEUTIANS, WED-SUN, FEB 21-FEB 25.  
 
MODERATE RISK OF MUCH ABOVE NORMAL TEMPERATURES FOR PORTIONS OF THE NORTHERN  
HALF OF MAINLAND ALASKA, WED-THU, FEB 21-FEB 22.  
 
HIGH WINDS FOR PARTS OF COASTAL CALIFORNIA, WED-THU, FEB 21-FEB 22.  
 
FROZEN PRECIPITATION FOR PARTS OF THE SOUTHERN PLAINS, THE LOWER MISSISSIPPI  
VALLEY, THE MIDDLE MISSISSIPPI VALLEY, THE OHIO VALLEY, AND THE GREAT LAKES,  
THU-FRI, FEB 22-FEB 23.  
 
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE LOWER MISSISSIPPI  
VALLEY, THE TENNESSEE VALLEY, THE SOUTHERN APPALACHIANS, THE SOUTHEAST, THE  
SOUTHERN PLAINS, AND THE OHIO VALLEY, WED-TUE, FEB 21-FEB 27.  
 
MODERATE RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE SOUTHEAST, THE LOWER  
MISSISSIPPI VALLEY, THE SOUTHERN PLAINS, AND THE TENNESSEE VALLEY, FRI-SUN, FEB  
23-FEB 25.  
 
FLOODING POSSIBLE ACROSS PORTIONS OF THE SOUTHEAST.  
 
FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY,  
THE TENNESSEE VALLEY, THE MID-ATLANTIC, THE SOUTHERN APPALACHIANS, THE  
SOUTHEAST, AND THE OHIO VALLEY.  
 
FLOODING LIKELY ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY AND THE  
TENNESSEE VALLEY.  
 
SEVERE DROUGHT ACROSS THE CENTRAL PLAINS, THE CENTRAL ROCKIES, THE LOWER  
MISSISSIPPI VALLEY, THE CENTRAL GREAT BASIN, THE NORTHERN PLAINS, THE TENNESSEE  
VALLEY, THE SOUTHERN ROCKIES, THE MIDDLE MISSISSIPPI VALLEY, THE MID-ATLANTIC,  
CALIFORNIA, THE SOUTHEAST, THE SOUTHERN APPALACHIANS, THE SOUTHERN PLAINS, AND  
THE SOUTHWEST.  
 
DETAILED SUMMARY  
 
FOR FRIDAY FEBRUARY 16 - TUESDAY FEBRUARY 20: A COLD FRONT STRETCHING FROM THE  
NORTHEAST TO THE SOUTHERN PLAINS IS PREDICTED TO PROPAGATE SOUTHEASTWARD ACROSS  
THE CONUS FROM THE BEGINNING TO MIDDLE OF THE 3 TO 7 DAY PERIOD. THIS FRONT MAY  
BRING HEAVY RAIN TO PARTS OF THE LOWER MISSISSIPPI VALLEY, THE TENNESSEE  
VALLEY, THE SOUTHERN APPALACHIANS, THE SOUTHERN PLAINS, AND THE OHIO VALLEY FEB  
16 TO 17. THE POTENTIAL FOR HEAVY RAIN IS EXPECTED TO SHIFT SOUTHEASTWARD TO  
PORTIONS OF THE LOWER MISSISSIPPI VALLEY, THE CENTRAL APPALACHIANS, THE  
TENNESSEE VALLEY, THE GREAT LAKES, THE SOUTHERN APPALACHIANS, THE SOUTHEAST,  
THE SOUTHERN PLAINS, AND THE OHIO VALLEY FEB 19 TO 20. THERE ARE INCREASED  
CHANCES FOR FROZEN PRECIPITATION INCLUDING FREEZING RAIN AND SLEET ALONG THE  
NORTHERN PERIPHERY OF THE HEAVY PRECIPITATION AREA, ACROSS PARTS OF THE MIDDLE  
MISSISSIPPI VALLEY, THE OHIO VALLEY, AND THE GREAT LAKES FEB 20. SOME MODELS  
INDICATE RAINFALL TOTALS IN SOME AREAS REACHING 2 INCHES OR GREATER IN A  
24-HOUR PERIOD.  
 
A COLD FRONT IS PREDICTED TO APPROACH THE PACIFIC NORTHWEST FEB 17 AND 18,  
WHILE A STATIONARY FRONT IS ANTICIPATED TO FORM OVER THE ROCKIES THROUGHOUT THE  
3 TO 7 DAY PERIOD. STRONG ONSHORE FLOW COMBINED WITH FORCING ASSOCIATED WITH  
THE STATIONARY FRONT MAY BRING HEAVY SNOW (ONE INCH OF LIQUID EQUIVALENT OR  
GREATER IN 24-HOURS) FEB 16 TO 18 ACROSS THE CASCADES, GREAT BASIN, AND  
NORTHERN ROCKIES. ADDITIONALLY, THIS PATTERN FAVORS HIGH WINDS FOR PORTIONS OF  
THE CENTRAL PLAINS, THE NORTHERN PLAINS, THE NORTHERN ROCKIES, THE CENTRAL  
ROCKIES, AND THE NORTHERN GREAT BASIN FEB 17 TO 18. SUSTAINED WIND SPEEDS MAY  
REACH 30 KNOTS OR GREATER IN LOCALIZED HIGHLIGHTED REGIONS.  
 
PERIODS OF SURFACE HIGH PRESSURE ARE ANTICIPATED TO BUILD ACROSS THE NORTHERN  
PART OF THE PACIFIC NORTHWEST AND THE NORTHERN AND CENTRAL PLAINS DURING THE 3  
TO 7 DAY PERIOD. THIS PATTERN MAY USHER IN MUCH BELOW NORMAL TEMPERATURES  
ACROSS PARTS OF THE NORTHERN PLAINS AND THE NORTHERN ROCKIES FEB 16 AND FEB 19  
TO 20. SOME AREAS MAY EXPERIENCE MINIMUM TEMPERATURES WITH NEGATIVE ANOMALIES  
OF 24 DEGREES F OR GREATER WITH TEMPERATURES REACHING NEGATIVE DOUBLE DIGITS  
(DEG F).  
 
SURFACE TROUGHING IS FORECAST TO FORM ALONG PARTS OF THE WEST COAST OF THE  
CONUS AT THE END OF THE 3 TO 7 DAY PERIOD. THIS MAY LEAD TO HIGH WINDS ACROSS  
PARTS OF COASTAL PORTIONS OF CENTRAL CALIFORNIA FEB 20. SUSTAINED WIND SPEEDS  
IN THIS AREA MAY REACH 30 KNOTS OR GREATER.  
 
TWO STORM SYSTEMS ARE PREDICTED TO FORM OVER THE BERING SEA DURING THE 3 TO 7  
DAY PERIOD. THE FIRST ONE MAY BRING HIGH WINDS AND SIGNIFICANT WAVE HEIGHTS TO  
MAINLY THE CENTRAL AND WESTERN PARTS OF THE ALEUTIANS ON FEB 16. HOWEVER, THE  
EXPECTED WIND SPEEDS AND HIGH WAVES MAY NOT REACH HAZARDS CRITERIA AND  
THEREFORE ARE NOT INCLUDED ON THE MAP AT THIS TIME. MEANWHILE, SURFACE HIGH  
PRESSURE IS ANTICIPATED TO BUILD ACROSS MUCH OF MAINLAND ALASKA, INCREASING  
CHANCES FOR MUCH ABOVE NORMAL TEMPERATURES ACROSS PARTS OF THE NORTH SLOPE FEB  
18 TO 20. SOME AREAS ACROSS THE NORTH SLOPE MAY EXPERIENCE TEMPERATURE  
DEPARTURES 40 DEGREES F OR GREATER THAN NORMAL.  
 
FOR WEDNESDAY FEBRUARY 21 - TUESDAY FEBRUARY 27: A HIGHLY AMPLIFIED PATTERN IS  
EXPECTED FOR WEEK-2, WITH MID-LEVEL RIDGING ACROSS ALASKA AND THE EASTERN HALF  
OF THE CONUS AND TROUGHING ACROSS THE WESTERN HALF OF THE CONUS. A BROAD AREA  
OF SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES IS HIGHLIGHTED ACROSS MUCH OF  
THE WESTERN HALF OF THE CONUS THROUGHOUT WEEK-2, EXCLUDING PARTS OF THE  
SOUTHWEST, SOUTHERN ROCKIES, AND TEXAS THROUGHOUT WEEK-2. AN AREA OF MODERATE  
RISK OF MUCH BELOW NORMAL TEMPERATURES IS IDENTIFIED FOR A SLIGHTLY SMALLER  
SUBSET REGION OF THE SLIGHT AREA FOR FEB 21 TO 23, WHILE A HIGH RISK AREA IS  
HIGHLIGHTED ACROSS NORTHERN PARTS OF THE PACIFIC NORTHWEST, THE NORTHERN  
ROCKIES, THE NORTHERN GREAT BASIN, AND THE NORTHERN PLAINS, FEB 21 TO 22. THE  
GEFS REFORECAST TOOL INDICATES A 20 PERCENT CHANCE OR GREATER OF REACHING THE  
LOWEST 1ST PERCENTILE COMPARED TO NORMAL FOR LOCALIZED PARTS OF THE NORTHWEST  
AND THE NORTHERN PLAINS, FEB 21 AND 22.  
 
MID-LEVEL RIDGING ACROSS ALASKA IS ANTICIPATED TO CONTINUE THE PATTERN FOR  
ANOMALOUSLY WARMER TEMPERATURES FOR MANY PARTS OF THE REGION. A BROAD AREA OF  
SLIGHT RISK FOR MUCH ABOVE NORMAL TEMPERATURES IS HIGHLIGHTED ACROSS MOST OF  
MAINLAND ALASKA AND THE ALEUTIANS, EXCLUDING SOUTHEASTERN ALASKA AND THE  
PANHANDLE, FEB 21 TO 25. A MODERATE RISK AREA EXISTS FOR THE NORTHERN HALF OF  
MAINLAND ALASKA FEB 21 TO 22. THE GEFS REFORECAST TOOL PREDICTS THESE AREAS  
REACHING THE 85TH PERCENTILE OR GREATER.  
 
SURFACE TROUGHING ALONG PARTS OF COASTAL CALIFORNIA IS PREDICTED TO EXTEND INTO  
WEEK-2. THIS PATTERN FAVORS INCREASED CHANCES FOR HIGH WINDS (30 KNOTS OR  
GREATER) ACROSS COASTAL CALIFORNIA FEB 21 TO 22.  
 
THE AFOREMENTIONED STATIONARY FRONT IN THE 3 TO 7 DAY PERIOD IS ANTICIPATED TO  
STRETCH FROM THE NORTHEAST TO THE SOUTHERN PLAINS THROUGHOUT WEEK-2. THIS  
PATTERN SUPPORTS ABOVE NORMAL RAINFALL ACROSS PARTS OF THE EASTERN HALF OF THE  
CONUS. A SLIGHT RISK OF HEAVY RAIN IS HIGHLIGHTED ACROSS PARTS OF THE LOWER  
MISSISSIPPI VALLEY, THE TENNESSEE VALLEY, THE SOUTHERN APPALACHIANS, THE  
SOUTHEAST, THE SOUTHERN PLAINS, AND THE OHIO VALLEY THROUGHOUT WEEK-2. A  
MODERATE RISK AREA IS IDENTIFIED ACROSS PARTS OF THE SOUTHEAST, THE LOWER  
MISSISSIPPI VALLEY, THE SOUTHERN PLAINS, AND THE TENNESSEE VALLEY, FEB 23 TO  
25. BOTH THE GEFS AND ECMWF REFORECAST TOOL INDICATE 3-DAY RAINFALL AMOUNTS  
REACHING NEARLY THE 85TH PERCENTILE OR GREATER IN THE HIGHLIGHTED REGION. THIS  
POTENTIAL FOR PROLONGED HEAVY RAINFALL IN COMBINATION WITH REGIONS IN THIS AREA  
CURRENTLY BEING AFFECTED BY FLOODING MAY INCREASE CHANCES FOR PROLONGED FLOOD  
CONDITIONS DURING WEEK-2 IN AREAS ALREADY IMPACTED BY FLOOD EAST OF THE  
MISSISSIPPI RIVER. ADDITIONALLY, THERE IS A POTENTIAL FOR FREEZING RAIN AND  
SLEET ALONG THE NORTHERN PERIPHERY OF THE HEAVY RAINFALL AREA, EXTENDING  
FURTHER NORTHEASTWARD. PARTS OF THE SOUTHERN PLAINS, THE LOWER MISSISSIPPI  
VALLEY, THE MIDDLE MISSISSIPPI VALLEY, THE OHIO VALLEY, AND THE GREAT LAKES IS  
HIGHLIGHTED FOR INCREASED CHANCES OF FROZEN PRECIPITATION, FEB 22 TO 23.  
 
THE U.S. DROUGHT MONITOR, VALID ON FEB 6 2018 INDICATES A SLIGHT INCREASE IN  
THE COVERAGE OF SEVERE TO EXCEPTIONAL DROUGHT (D2-D4) FROM 17.21% LAST WEEK TO  
18.44% THIS WEEK. DRYNESS AND DROUGHT HAVE INCREASED IN SPATIAL COVERAGE AND/OR  
INTENSIFIED OVER PORTIONS OF NORTHERN TEXAS AND WESTERN OKLAHOMA. SOME  
DETERIORATION IN CONDITIONS IS ALSO NOTED OVER THE SOUTHEAST.  
 
FORECASTER: MELISSA OU  
 

 
 
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