353  
FXUS21 KWNC 152119  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST FEBRUARY 15 2018  
 
SYNOPSIS: AN ACTIVE WEATHER PATTERN IS PREDICTED ACROSS THE CONTIGUOUS U.S. AND  
ALASKA DURING THE NEXT TWO WEEKS. DURING THE 3-7 DAY AND WEEK-2 FORECAST  
PERIODS, ON AVERAGE, A FRONTAL ZONE IS EXPECTED TO STRETCH FROM THE SOUTHERN  
GREAT PLAINS NORTHEASTWARD ACROSS THE OHIO VALLEY AND GREAT LAKES REGION. MIXED  
PRECIPITATION TYPES, AND THUNDERSTORMS, ARE ANTICIPATED ACROSS PORTIONS OF THIS  
REGION. IN GENERAL, WARMER THAN NORMAL TEMPERATURES ARE EXPECTED EAST OF THIS  
FRONTAL ZONE, AND COLDER THAN NORMAL TEMPERATURES ARE PREDICTED WEST OF THIS  
FRONTAL ZONE.  
 
HAZARDS  
 
HEAVY PRECIPITATION ACROSS PORTIONS OF THE GREAT LAKES AND THE UPPER  
MISSISSIPPI VALLEY, MON, FEB 19.  
 
HEAVY RAIN ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY, THE TENNESSEE  
VALLEY, THE SOUTHERN PLAINS, THE MIDDLE MISSISSIPPI VALLEY, THE GREAT LAKES,  
AND THE OHIO VALLEY, TUE-WED, FEB 20-FEB 21.  
 
HEAVY RAIN ACROSS PORTIONS OF THE GREAT LAKES, THE MIDDLE MISSISSIPPI VALLEY,  
THE LOWER MISSISSIPPI VALLEY, THE SOUTHERN PLAINS, AND THE OHIO VALLEY,  
SUN-MON, FEB 18-FEB 19.  
 
FLOODING POSSIBLE ACROSS PORTIONS OF THE CENTRAL APPALACHIANS AND THE OHIO  
VALLEY.  
 
FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY,  
THE OHIO VALLEY, AND THE TENNESSEE VALLEY.  
 
FLOODING LIKELY ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY.  
 
HIGH WINDS ACROSS PORTIONS OF CALIFORNIA, MON-TUE, FEB 19-FEB 20.  
 
HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE NORTHERN PLAINS, AND THE  
NORTHERN ROCKIES, SUN-MON, FEB 18-FEB 19.  
 
MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE CENTRAL GREAT BASIN, THE  
NORTHERN PLAINS, THE NORTHERN ROCKIES, THE CENTRAL ROCKIES, CALIFORNIA, THE  
NORTHERN GREAT BASIN, THE PACIFIC NORTHWEST, AND THE SOUTHWEST, MON-WED, FEB  
19-FEB 21.  
 
MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE CENTRAL PLAINS, THE UPPER  
MISSISSIPPI VALLEY, THE MIDDLE MISSISSIPPI VALLEY, THE NORTHERN PLAINS, AND THE  
NORTHERN ROCKIES, SUN-THU, FEB 18-FEB 22.  
 
MUCH ABOVE NORMAL TEMPERATURES ACROSS PORTIONS OF MAINLAND ALASKA AND THE  
ALEUTIANS, SUN-THU, FEB 18-FEB 22.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE CENTRAL  
PLAINS, THE CENTRAL GREAT BASIN, THE NORTHERN PLAINS, THE NORTHERN ROCKIES, THE  
CENTRAL ROCKIES, THE MIDDLE MISSISSIPPI VALLEY, CALIFORNIA, THE NORTHERN GREAT  
BASIN, THE UPPER MISSISSIPPI VALLEY, THE ALASKA PANHANDLE, THE PACIFIC  
NORTHWEST, AND THE SOUTHWEST, FRI-THU, FEB 23-MAR 1.  
 
SLIGHT RISK OF MUCH ABOVE NORMAL TEMPERATURES FOR PORTIONS OF MAINLAND ALASKA  
AND THE ALEUTIANS, FRI-THU, FEB 23-MAR 1.  
 
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE CENTRAL  
PLAINS, THE CENTRAL GREAT BASIN, THE NORTHERN PLAINS, THE NORTHERN ROCKIES,  
CALIFORNIA, THE NORTHERN GREAT BASIN, THE PACIFIC NORTHWEST, AND THE SOUTHWEST,  
FRI-SUN, FEB 23-FEB 25.  
 
HIGH RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE NORTHERN  
PLAINS, THE NORTHERN ROCKIES, CALIFORNIA, THE NORTHERN GREAT BASIN, AND THE  
PACIFIC NORTHWEST, FRI-SUN, FEB 23-FEB 25.  
 
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE CENTRAL PLAINS, THE  
LOWER MISSISSIPPI VALLEY, THE TENNESSEE VALLEY, THE MIDDLE MISSISSIPPI VALLEY,  
THE SOUTHERN APPALACHIANS, THE SOUTHEAST, THE SOUTHERN PLAINS, AND THE OHIO  
VALLEY, FRI-SUN, FEB 23-FEB 25.  
 
MODERATE RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE MIDDLE MISSISSIPPI  
VALLEY, THE LOWER MISSISSIPPI VALLEY, THE SOUTHERN PLAINS, THE OHIO VALLEY, AND  
THE TENNESSEE VALLEY, FRI-SUN, FEB 23-FEB 25.  
 
SEVERE DROUGHT ACROSS THE CENTRAL PLAINS, THE CENTRAL ROCKIES, THE LOWER  
MISSISSIPPI VALLEY, THE CENTRAL GREAT BASIN, THE NORTHERN PLAINS, THE SOUTHERN  
ROCKIES, THE MIDDLE MISSISSIPPI VALLEY, CALIFORNIA, THE SOUTHERN PLAINS, AND  
THE SOUTHWEST.  
 
DETAILED SUMMARY  
 
FOR SUNDAY FEBRUARY 18 - THURSDAY FEBRUARY 22: AN AREA OF MIXED PRECIPITATION  
IS FORECAST TO OVERSPREAD THE MID-ATLANTIC AND NORTHEAST THIS WEEKEND, WITH  
MOST OF THE PRECIPITATION EXPECTED TO FALL PRIOR TO THE START OF THE HAZARDS  
PERIOD ON SUNDAY. THE HEAVILY POPULATED METROPOLITAN AREAS ALONG THE I-95  
CORRIDOR MAY RECEIVE LIGHT SNOW ACCUMULATIONS WITH THIS LOW PRESSURE SYSTEM ON  
SUNDAY, THOUGH NOT ENOUGH TO WARRANT A HAZARDOUS DESIGNATION.  
 
SEVERAL STORM SYSTEMS ARE FORECAST TO PRODUCE SIGNIFICANT RAINFALL (GENERALLY  
2-4 INCHES) ACROSS PORTIONS OF THE EAST-CENTRAL CONUS DURING THIS PERIOD. THIS  
IS IN RESPONSE TO THE EXPECTED AMPLIFICATION OF THE MID-LEVEL TROUGH WEST OF  
THAT AREA, AND THE DOWNSTREAM RIDGE OVER THE SOUTHEAST. AS MOIST, UNSTABLE GULF  
AIR STREAMS NORTHWARD INTO THIS REGION, STRONG THUNDERSTORMS ARE ALSO A  
POSSIBILITY, THOUGH AT THIS TIME, THE STORM PREDICTION CENTER DOES NOT DEPICT A  
SEVERE THREAT FOR THE REGION. WITH TEMPERATURES NEAR FREEZING ACROSS THE UPPER  
GREAT LAKES REGION, A SWATH OF HEAVY PRECIPITATION (IN THIS CASE, PRIMARILY  
SNOW AND SLEET) IS PREDICTED ON FEB 19.  
 
IN LOWER MICHIGAN, WHERE AT LEAST 4-8 INCHES OF SNOW REMAINS ON THE GROUND,  
ALREADY SATURATED SOILS, AND THE INTRODUCTION OF WARMER TEMPERATURES AND RAIN,  
COULD RESULT IN AREAS OF LOCALIZED FLOODING. FOR ADDITIONAL INFORMATION, PLEASE  
CONSULT THE LATEST AVAILABLE STREAM FLOW INFORMATION AT THE NORTH CENTRAL RIVER  
FORECAST CENTER (NCRFC) AT HTTPS://WWW.WEATHER.GOV/NCRFC/ . FLOODING IS ALSO  
POSSIBLE, LIKELY, IMMINENT, OR ONGOING ACROSS PARTS OF MISSISSIPPI AND THE OHIO  
VALLEY (INCLUDING SOUTHWESTERN PENNSYLVANIA).  
 
CANADIAN HIGH PRESSURE IS EXPECTED TO SINK SOUTHWARD ACROSS THE NORTHERN AND  
CENTRAL PLAINS, USHERING IN ARCTIC AIR ON BLUSTERY WINDS. WIND SPEEDS OF 30  
KNOTS ARE PREDICTED ON FEB 18-19, WHILE TEMPERATURES ARE EXPECTED TO RANGE FROM  
12 TO 36 DEGREES BELOW NORMAL. IN THE MOST EXTREME CASE (CENTRAL AND EASTERN  
PARTS OF MONTANA), WHERE THE NORMAL OVERNIGHT LOW IS ABOUT 12 DEGREES F, A  
DEPARTURE OF 36 DEGREES F BELOW NORMAL BRINGS THE FORECASTED TEMPERATURE DOWN  
TO ABOUT -24 DEGREES F. SOME OF THIS UNSEASONABLY COLD AIR IS PREDICTED TO  
SPILL WEST OF THE CONTINENTAL DIVIDE, COVERING MUCH OF THE WESTERN CONUS.  
HOWEVER, THE TEMPERATURE DEPARTURES ARE FORECAST TO RANGE ONLY FROM ABOUT 12 TO  
16 DEGREES F BELOW NORMAL, MAKING FOR LESS EXTREME CONDITIONS AS COMPARED TO  
THOSE EAST OF THE DIVIDE. STRONG NORTHERLY WINDS (ABOUT 30 KNOTS) ASSOCIATED  
WITH THIS COLD AIR MASS ARE ANTICIPATED ALONG THE CALIFORNIA COAST, FEB 19-20.  
 
IN NORTHERN AND WESTERN ALASKA, TEMPERATURES ARE FORECAST TO RANGE FROM 20-35  
DEGREES F ABOVE NORMAL DURING THE 3-7 DAY PERIOD. THIS MUCH MILDER PATTERN IS  
DUE TO AN EXTENSIVE SOUTHERLY FETCH OF LOW-LEVEL AIR FROM THE NORTH PACIFIC,  
AND DOWNSLOPE WINDS ACROSS THE NORTHERN SLOPES OF BOTH THE ALASKA RANGE AND THE  
BROOKS RANGE. INCIDENTALLY, THOUGH NOT A SPECIFIC HAZARD TO PUT ON THE MAP,  
THERE IS CONSIDERABLY LESS ICE THAN NORMAL IN THE BERING SEA AT THIS TIME. THE  
ICE EDGE IS FAR TO THE NORTH FOR THIS TIME OF YEAR, AND OPEN WATER IS NOW BEING  
ANALYZED WITHIN THE ICE EDGE, EVEN CLOSE TO SHORE AND IN THE CHUKCHI/BERING  
STRAIT REGION. THIS MEANS REPETITIVE SURF COULD BE PROBLEMATIC FOR PARTS OF  
ALASKA'S WEST COAST.  
 
FOR FRIDAY FEBRUARY 23 - THURSDAY MARCH 01: A SLIGHT WESTWARD SHIFT IN THE  
MID-LEVEL FLOW PATTERN IS FORECAST DURING WEEK-2 ACROSS NORTH AMERICA. A SLIGHT  
RISK OF MUCH ABOVE NORMAL TEMPERATURES IS INDICATED FOR MUCH OF ALASKA  
(EXCLUDING THE SOUTHEAST MAINLAND AND THE PANHANDLE REGION), DUE TO A PREDICTED  
MID-TROPOSPHERIC RIDGE, FEB 23-MAR 1. IN CONTRAST, THERE IS A SLIGHT RISK OF  
MUCH BELOW NORMAL TEMPERATURES ACROSS THE ALASKA PANHANDLE FOR THE SAME PERIOD.  
THIS SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES ALSO INCORPORATES MUCH OF  
THE WESTERN AND NORTH-CENTRAL CONUS, FEB 23-MAR 1, ASSOCIATED WITH A MID-LEVEL  
TROUGH. MODERATE AND HIGH RISK AREAS CONSTITUTE SIGNIFICANT SUBSETS OF THIS  
REGION, FEB 23-25. THERE IS A SIGNIFICANT SOUTHWARD EXTENSION OF THE MODERATE  
AND HIGH RISK AREAS ACROSS CALIFORNIA COMPARED TO YESTERDAY.  
 
ACROSS EAST-CENTRAL PORTIONS OF THE LOWER 48 STATES, THERE IS A SLIGHT RISK OF  
HEAVY PRECIPITATION FROM CENTRAL TEXAS EASTWARD AND NORTHEASTWARD ACROSS THE  
LOWER AND MIDDLE MISSISSIPPI VALLEY, THE OHIO AND TENNESSEE VALLEYS, AND THE  
SOUTHERN APPALACHIANS, FEB 23-25. AN EMBEDDED MODERATE RISK AREA IS ALSO  
PREDICTED, WHICH COVERS A LARGE FRACTION OF THIS SAME REGION, FEB 23-25. THERE  
ARE SUBSTANTIAL DIFFERENCES BETWEEN THE ECMWF ENSEMBLE MEAN AND GEFS PEO  
(PROBABILITY OF EXTREMES OUTLOOK) PRECIPITATION TOOLS, THOUGH THE MAIN AXIS OF  
THE EXPECTED HEAVY PRECIPITATION APPEARS CONSISTENT WITH YESTERDAY'S OUTLOOK.  
 
 
 
THE U.S. DROUGHT MONITOR, VALID ON FEB 13, 2018 INDICATES A SLIGHT DECREASE IN  
THE COVERAGE OF SEVERE TO EXCEPTIONAL DROUGHT (D2-D4) FROM 18.44% LAST WEEK TO  
18.04% THIS WEEK. A FEW OF THE MORE SUBSTANTIAL REVISIONS MADE TO THE MAP THIS  
WEEK INCLUDE AN INCREASE IN D2 COVERAGE ACROSS SOUTHERN CALIFORNIA, THE  
ELIMINATION OF ALL D2 AREAS ACROSS THE GULF COAST STATES FROM LOUISIANA TO  
FLORIDA, AND SIGNIFICANT 1-CATEGORY IMPROVEMENTS RENDERED ACROSS THE CAROLINAS,  
MID-ATLANTIC, AND NORTHEAST.  
 
FORECASTER: ANTHONY ARTUSA  
 

 
 
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