544  
FXUS21 KWNC 232026  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST FEBRUARY 23 2018  
 
SYNOPSIS: THE 3-7 DAY PERIOD WILL FEATURE WIDESPREAD COLD THROUGHOUT THE  
WESTERN CONUS WITH AREAS OF HEAVY PRECIPITATION SCATTERED THROUGHOUT  
WASHINGTON, OREGON, AND NORTHERN CALIFORNIA. A COUPLE OF LOW PRESSURE SYSTEMS  
WILL BRING HEAVY RAIN TO THE KENTUCKY, TENNESSEE, ARKANSAS AREA, AS WELL AS THE  
POSSIBILITY OF SEVERE WEATHER OVER EASTERN TEXAS, NORTHERN LOUISIANA, AND  
SOUTHERN ARKANSAS AS WE TRANSITION INTO MARCH. WEATHER IN THE WESTERN U.S. IS  
EXPECTED TO REMAIN UNSETTLED AS UPPER-LEVEL DISTURBANCES MOVE THROUGH BRINGING  
THE POTENTIAL FOR BELOW NORMAL TEMPERATURES AND HEAVY PRECIPITATION DURING THE  
ENTIRE FORECAST PERIOD.  
 
HAZARDS  
 
HEAVY PRECIPITATION ACROSS PORTIONS OF THE PACIFIC NORTHWEST AND THE NORTHERN  
GREAT BASIN, TUE-FRI, FEB 27-MAR 2.  
 
HEAVY PRECIPITATION ACROSS PORTIONS OF THE CENTRAL GREAT BASIN AND CALIFORNIA,  
MON-TUE, FEB 26-FEB 27.  
 
HEAVY RAIN ACROSS PORTIONS OF CALIFORNIA AND THE PACIFIC NORTHWEST, THU-FRI,  
MAR 1-MAR 2.  
 
HEAVY RAIN ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI VALLEY, THE LOWER  
MISSISSIPPI VALLEY, THE SOUTHERN APPALACHIANS, THE OHIO VALLEY, AND THE  
TENNESSEE VALLEY, WED-THU, FEB 28-MAR 1.  
 
SEVERE WEATHER ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY AND THE SOUTHERN  
PLAINS, WED, FEB 28.  
 
FLOODING POSSIBLE ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY, THE CENTRAL  
APPALACHIANS, THE TENNESSEE VALLEY, THE GREAT LAKES, THE MIDDLE MISSISSIPPI  
VALLEY, THE MID-ATLANTIC, THE SOUTHERN PLAINS, AND THE OHIO VALLEY.  
 
FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY,  
THE TENNESSEE VALLEY, THE GREAT LAKES, THE MIDDLE MISSISSIPPI VALLEY, THE UPPER  
MISSISSIPPI VALLEY, THE SOUTHERN PLAINS, AND THE OHIO VALLEY.  
 
FLOODING LIKELY ACROSS PORTIONS OF THE SOUTHERN APPALACHIANS, THE MIDDLE  
MISSISSIPPI VALLEY, THE GREAT LAKES, THE CENTRAL APPALACHIANS, AND THE OHIO  
VALLEY.  
 
MUCH BELOW NORMAL TEMPERATURES ACROSS MOST OF THE WESTERN CONUS, MON-FRI, FEB  
26-MAR 2.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE CENTRAL  
PLAINS, THE NORTHERN PLAINS, THE NORTHERN ROCKIES, THE CENTRAL ROCKIES, THE  
MIDDLE MISSISSIPPI VALLEY, THE NORTHERN GREAT BASIN, THE UPPER MISSISSIPPI  
VALLEY, AND THE PACIFIC NORTHWEST, SUN-TUE, MAR 4-MAR 6.  
 
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE CENTRAL  
PLAINS, THE NORTHERN PLAINS, THE NORTHERN ROCKIES, THE MIDDLE MISSISSIPPI  
VALLEY, THE NORTHERN GREAT BASIN, AND THE UPPER MISSISSIPPI VALLEY, SUN-TUE,  
MAR 4-MAR 6.  
 
HIGH RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE NORTHERN  
PLAINS, THE NORTHERN ROCKIES, AND THE NORTHERN GREAT BASIN, SUN-TUE, MAR 4-MAR  
6.  
 
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF CALIFORNIA, THE CENTRAL  
GREAT BASIN, THE PACIFIC NORTHWEST, THE NORTHERN GREAT BASIN, AND THE  
SOUTHWEST, THU-FRI, MAR 8-MAR 9.  
 
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 MONDAY FEBRUARY 26 - FRIDAY MARCH 02: A LOW PRESSURE SYSTEM THAT FORMS EAST  
OF THE ROCKIES OVER THE TEXAS PANHANDLE IS EXPECTED TO BRING HEAVY RAINFALL TO  
THE LOWER MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS DURING FEB. 28 - MAR. 1. THE  
HEAVIEST RAIN IS FORECAST TO FALL OVER KENTUCKY, WESTERN TENNESSEE,  
SOUTHEASTERN MISSOURI, AND NORTHERN ARKANSAS WHERE AMOUNTS COULD EXCEED 2.5  
INCHES IN A 24 HOUR PERIOD. DYNAMICAL GUIDANCE SUGGESTS THAT SEVERE WEATHER  
COULD DEVELOP ALONG A COLD FRONT ASSOCIATED WITH THIS LOW ON FEB. 28.  
 
A SERIES OF UPPER-LEVEL TROUGHS IS EXPECTED TO TRAVEL OVER THE NORTHWESTERN  
CONUS DURING THE 3-7 DAY FORECAST PERIOD LEADING TO MUCH BELOW NORMAL  
TEMPERATURES. SURFACE LOWS ASSOCIATED WITH THESE TROUGHS WILL PROBABLY BRING  
HEAVY PRECIPITATION TO THE CASCADES REGION OF THE PACIFIC NORTHWEST DURING THE  
FEB. 27 - MAR. 1 PERIOD. TEMPERATURES ARE FORECAST TO BE COLD ENOUGH TO SUPPORT  
SNOW AND LIQUID EQUIVALENTS OF 2-3 INCHES/DAY ARE POSSIBLE. THESE SYSTEMS ARE  
ALSO LIKELY TO BRING HEAVY RAIN TO THE WESTERN OREGON/CALIFORNIA BORDER DURING  
MAR. 1-2 WHERE AMOUNTS COULD EXCEED 1.5 INCHES/DAY. HEAVY PRECIPITATION IS ALSO  
EXPECTED IN THE CENTRAL SIERRA NEVADAS JUST WEST OF CARSON CITY. PRECIPITATION  
COULD REACH LIQUID EQUIVALENTS GREATER THAN 1.25 INCHES/DAY IN THIS REGION  
DURING THE FEB. 26-27 PERIOD.  
 
SNOW MELT AND HEAVY RAINFALL DURING THE PERIOD IN AREAS THAT HAVE FROZEN GROUND  
MAY CAUSE AREAS OF FLOODING ACROSS PORTIONS OF THE SOUTHERN PLAINS, MISSISSIPPI  
VALLEY, THE OHIO VALLEY, AND THE GREAT LAKES REGION.  
 
A CYCLONE IN THE BERING SEA IS LIKELY TO BRING STRONG WINDS TO THE ALEUTIAN  
ISLANDS AND ALASKA PENINSULA ON FEB. 26, BUT THESE WILL PROBABLY BE UNDER OUR  
HAZARDOUS THRESHOLD.  
 
FOR SATURDAY MARCH 03 - FRIDAY MARCH 09: THE WESTERN HALF OF THE CONUS WILL BE  
UNSETTLED DURING WEEK-2. AN UPPER-LEVEL TROUGH IS FORECAST TO BRING HIGH  
CHANCES OF MUCH BELOW NORMAL TEMPERATURES TO THE NORTHERN ROCKIES AND NORTHERN  
PLAINS DURING FEB. 4-6. BOTH THE GFS AND THE ECMWF MODELS HAVE LOCKED ON TO  
THIS COLD OVER THE PAST FEW DAYS, SO CONFIDENCE IS HIGHER THAN NORMAL FOR THIS  
FORECAST PERIOD. THE GFS AND CFS ARE BOTH HINTING AT A SURFACE LOW MOVING INTO  
CENTRAL CALIFORNIA DURING THE FINAL TWO DAYS OF THE FORECAST PERIOD, WHICH MAY  
BRING HEAVY PRECIPITATION TO THAT REGION.  
 
THE U.S. DROUGHT MONITOR, VALID ON FEB 20, 2018 INDICATES A SLIGHT DECREASE IN  
THE COVERAGE OF SEVERE TO EXCEPTIONAL DROUGHT (D2-D4) FROM 18.04% LAST WEEK TO  
17.76% THIS WEEK. A FEW OF THE MORE SUBSTANTIAL REVISIONS MADE TO THE MAP THIS  
WEEK INCLUDE AN INCREASE IN THE D1 COVERAGE OVER OREGON, A DECREASE IN THE D3  
COVERAGE OVER NORTHERN TEXAS, AND THE ADDITION OF D3 COVERAGE OVER THE FOUR  
CORNERS REGION.  
 
FORECASTER: KYLE MACRITCHIE  
 

 
 
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