088  
FXUS21 KWNC 262116  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST FEBRUARY 26 2018  
 
SYNOPSIS: A SURFACE LOW IS PREDICTED TO TRACK FROM THE OHIO VALLEY  
NORTHEASTWARD TO THE NORTHEAST MAR 1 TO 3. A SERIES OF SURFACE LOWS ARE  
ANTICIPATED TO APPROACH THE WEST COAST OF THE LOWER 48 STATES THROUGHOUT THE 3  
TO 7 DAY PERIOD. STRONG ONSHORE FLOW IS FORECAST FOR PARTS OF THE WEST COAST OF  
THE CONTIGUOUS U.S. THROUGHOUT WEEK-2. DURING WEEK-2, MID-LEVEL LOW PRESSURE IS  
FAVORED FOR THE EASTERN HALF OF THE LOWER 48 STATES AND PARTS OF MAINLAND  
ALASKA, WHILE MID-LEVEL HIGH PRESSURE IS EXPECTED OVER THE ALEUTIANS, ALASKA  
PANHANDLE, AND THE WESTERN HALF OF THE CONTIGUOUS U.S.  
 
HAZARDS  
 
HEAVY RAIN ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY, THE SOUTHERN  
APPALACHIANS, AND THE TENNESSEE VALLEY, THU, MAR 1.  
 
HEAVY PRECIPITATION ACROSS PORTIONS OF THE NORTHEAST, THE CENTRAL APPALACHIANS,  
THE MIDDLE MISSISSIPPI VALLEY, THE MID-ATLANTIC, THE UPPER MISSISSIPPI VALLEY,  
THE GREAT LAKES, AND THE OHIO VALLEY, THU-FRI, MAR 1-MAR 2.  
 
HIGH WINDS ACROSS COASTAL PARTS OF THE NORTHEAST AND MID-ATLANTIC, FRI-SAT, MAR  
2-MAR 3.  
 
HEAVY SNOW ACROSS PORTIONS OF NORTHERN CALIFORNIA, THE SIERRAS, AND CASCADES,  
THU-SAT, MAR 1-MAR 3.  
 
HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN ROCKIES AND THE NORTHERN GREAT  
BASIN, THU, MAR 1.  
 
HIGH WINDS ACROSS PORTIONS OF THE CENTRAL PLAINS, THE NORTHERN PLAINS, AND THE  
NORTHERN ROCKIES, SAT, MAR 3.  
 
HIGH WINDS ACROSS PORTIONS OF THE CENTRAL GREAT BASIN, THE SOUTHWEST, AND  
CENTRAL AND SOUTHERN ROCKIES, FRI-SAT, MAR 2-MAR 3.  
 
MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF CALIFORNIA, THE CENTRAL GREAT  
BASIN, THE PACIFIC NORTHWEST, THE NORTHERN GREAT BASIN, AND THE SOUTHWEST,  
SAT-MON, MAR 3-MAR 5.  
 
FLOODING POSSIBLE ACROSS PORTIONS OF 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 MIDDLE MISSISSIPPI VALLEY, THE LOWER  
MISSISSIPPI VALLEY, THE SOUTHERN PLAINS, AND THE OHIO VALLEY.  
 
HIGH SIGNIFICANT WAVE HEIGHTS FOR COASTAL PORTIONS OF THE ALEUTIANS, SAT-SUN,  
MAR 3-MAR 4.  
 
MUCH ABOVE NORMAL TEMPERATURES ACROSS PORTIONS OF THE NORTH SLOPE OF ALASKA,  
FRI-MON, MAR 2-MAR 5.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE NORTHWESTERN  
QUARTER OF THE CONUS, TUE-THU, MAR 6-MAR 8.  
 
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE NORTHERN  
PLAINS AND THE NORTHERN ROCKIES, TUE-THU, MAR 6-MAR 8.  
 
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF MAINLAND ALASKA,  
TUE-THU, MAR 6-MAR 8.  
 
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE CENTRAL GREAT BASIN, AND  
CALIFORNIA, THU-SAT, MAR 8-MAR 10.  
 
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 THURSDAY MARCH 01 - MONDAY MARCH 05: A SURFACE LOW IS FORECAST TO FORM OVER  
THE OHIO VALLEY AT THE BEGINNING OF THE PERIOD AND TRACK NORTHEASTWARD TO THE  
NORTHEAST COAST BY MAR 2. A COLD FRONT STRETCHING FROM THE CENTER OF THIS LOW  
TO THE LOWER MISISSIPPI VALLEY MAY BRING HEAVY RAIN (ONE INCH OF RAINFALL OR  
GREATER IN 24-HOURS) TO PORTIONS OF THE LOWER MISSISSIPPI VALLEY, THE SOUTHERN  
APPALACHIANS, AND THE TENNESSEE VALLEY, MAR 1. THIS LOW MAY ALSO BRING HEAVY  
RAIN AND SNOW TO PARTS OF THE NORTHEAST, THE CENTRAL APPALACHIANS, THE MIDDLE  
MISSISSIPPI VALLEY, THE MID-ATLANTIC, THE UPPER MISSISSIPPI VALLEY, THE GREAT  
LAKES, AND THE OHIO VALLEY, MAR 1 TO 2. THE GREATEST CHANCES FOR HEAVY SNOW ARE  
ACROSS THE GREAT LAKES, OHIO VALLEY, AND NORTHEAST. SOME MODELS INDICATE THE  
POTENTIAL FOR LOCALIZED AREAS RECEIVING LIQUID EQUIVALENT AMOUNTS OF TWO INCHES  
OR GREATER IN A 24-HOUR PERIOD. AS THIS STORM EXITS THE EAST COAST OF THE  
CONUS, COASTAL AREAS ALONG THE NORTHEAST AND MID-ATLANTIC MAY EXPERIENCE HIGH  
WINDS (40 KNOTS OR GREATER), MAR 2 TO 3. MANY AREAS ACROSS THE MISSISSIPPI,  
TENNESSEE, AND OHIO VALLEY, AND THE GREAT LAKES ARE CURRENTLY EXPERIENCING  
FLOODING. EXPECTED UPCOMING HEAVY PRECIPITATION MAY EXACERBATE THESE AREAS  
ALREADY EXPERIENCING FLOOD.  
 
SURFACE LOW PRESSURE IS PREDICTED TO APPROACH THE PACIFIC NORTHWEST BY MAR 1.  
THIS SURFACE LOW AND ITS TRAILING COLD FRONT MAY BRING HEAVY SNOW TO PORTIONS  
OF THE NORTHERN ROCKIES AND THE NORTHERN GREAT BASIN, MAR 1, AND TO NORTHERN  
CALIFORNIA, THE SIERRAS, AND CASCADES, MAR 1 TO 3. PARTS OF THE CASCADES MAY  
RECEIVE THE GREATEST SNOWFALL, WITH LOCALIZED AREAS POTENTIALLY RECEIVING UP TO  
TWO INCHES OR GREATER OF LIQUID EQUIVALENT IN 24 HOURS. THIS COLD FRONT MAY  
ALSO INCREASE CHANCES FOR HIGH WINDS (SUSTAINED WIND SPEEDS OF 40 KNOTS OR  
GREATER) ACROSS PARTS OF THE CENTRAL GREAT BASIN, SOUTHWEST, AND CENTRAL AND  
SOUTHERN ROCKIES, MAR 2 TO 3.  
 
A STATIONARY FRONT IS ANTICIPATED TO FORM IN THE LEE OF THE ROCKIES BY MAR 2  
AND REMAIN FAIRLY STATIONARY UNTIL THE END OF THE 3 TO 7 DAY PERIOD. THIS  
PATTERN FAVORS HIGH WINDS (30 KNOTS OR GREATER) ACROSS PORTIONS OF THE CENTRAL  
PLAINS, THE NORTHERN PLAINS, AND THE NORTHERN ROCKIES, MAR 3. SURFACE HIGH  
PRESSURE IS EXPECTED TO BUILD ACROSS THE WESTERN CONUS WEST OF THIS STATIONARY  
FRONT. THIS SURFACE HIGH MAY BRING COLD ARCTIC AIR FROM CANADA INTO PARTS OF  
THE WESTERN CONUS, SUPPORTING AN INCREASED LIKELIHOOD FOR MUCH BELOW NORMAL  
TEMPERATURES ACROSS PORTIONS OF CALIFORNIA, THE CENTRAL GREAT BASIN, THE  
PACIFIC NORTHWEST, THE NORTHERN GREAT BASIN, AND THE SOUTHWEST, MAR 3 TO 5. THE  
GREATEST TEMPERATURE ANOMALIES ARE EXPECTED FOR NEVADA, WHERE LOCALIZED AREAS  
MAY EXPERIENCE MINIMUM TEMPERATURES 24 DEG F BELOW NORMAL, WITH TEMPERATURES IN  
THE NEGATIVE SINGLE DIGITS.  
 
A STORM SYSTEM IN THE BERING SEA MAY SUPPORT PERSISTENT, STRONG SOUTHWESTERLY  
FLOW FROM THE MIDDLE TO END OF THE DAY 3 TO 7 PERIOD. THIS PATTERN FAVORS HIGH  
SIGNIFICANT WAVE HEIGHTS (24 FEET OR GREATER) ACROSS COASTAL PARTS OF THE  
ALEUTIANS, MAR 3 TO 4. STRONG SOUTHERLY FLOW IS ANTICIPATED FOR PARTS OF  
MAINLAND ALASKA DURING THE 3 TO 7 DAY PERIOD. THIS FLOW PATTERN, IN COMBINATION  
WITH BELOW NORMAL ICE COVER IN THE BERING SEA ALONG THE WEST COAST OF MAINLAND  
ALASKA, FAVORS MUCH ABOVE NORMAL TEMPERATURES ACROSS THE NORTH SLOPE. SOME  
AREAS IN THIS REGION MAY EXPERIENCE TEMPERATURES 40 DEG F ABOVE NORMAL.  
 
FOR TUESDAY MARCH 06 - MONDAY MARCH 12: MID-LEVEL TROUGHING IS FORECAST FOR THE  
NORTHWESTERN QUARTER OF THE CONUS FROM THE BEGINNING TO MIDDLE OF WEEK-2,  
SUPPORTING A SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES IN THIS AREA MAR 6  
TO 8. MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES IS IDENTIFIED FOR  
PORTIONS OF THE NORTHERN PLAINS AND THE NORTHERN ROCKIES, MAR 6 TO 8. MID-LEVEL  
TROUGHING IS ANTICIPATED ACROSS MOST OF MAINLAND ALASKA, SUPPORTING A SLIGHT  
RISK OF MUCH BELOW NORMAL TEMPERATURES ACROSS PARTS OF MAINLAND ALASKA, MAR 6  
TO 8. THE GEFS REFORECAST TOOL INDICATES A 20% CHANCE OR GREATER OF THE MINIMUM  
TEMPERATURE IN THE AFOREMENTIONED REGIONS REACHING THE LOWEST 15TH PERCENTILE  
COMPARED TO NORMAL.  
 
IN GENERAL, THE MEAN PATTERN FOR WEEK-2 FAVORS MID-LEVEL TROUGHING ACROSS THE  
NORTHEASTERN PACIFIC OCEAN INTO PARTS OF WESTERN CONUS. THIS PATTERN SUPPORTS  
STRONG ONSHORE FLOW TO PARTS OF THE WESTERN CONUS. THIS PATTERN SUPPORT SLIGHT  
RISK OF HEAVY PRECIPITATION FOR PARTS OF THE CENTRAL GREAT BASIN, AND  
CALIFORNIA, MAR 8 TO 10. HOWEVER, THERE IS SIGNIFICANT DISAGREEMENT FURTHER  
NORTH IN THE NORTHERN GREAT BASIN. THE GEFS REFORECAST TOOL SHOWS A 20 PERCENT  
CHANCE OR GREATER OF THE NORTHERN GREAT BASIN RECEIVING HEAVY PRECIPITATION  
THROUGHOUT WEEK-2, WHEREAS THE ECMWF HAS A MUCH DRIER SOLUTION. THE HEAVY  
PRECIPITATION AREA HIGHLIGHTED DENOTES WHERE THE GEFS AND ECMWF REFORECAST TOOL  
SHOW AGREEMENT REGARDING ENHANCED CHANCES FOR HEAVY PRECIPITATION BOTH  
SPATIALLY AND TEMPORALLY.  
 
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: MELISSA OU  
 

 
 
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