023  
FXUS21 KWNC 082006  
PMDTHR  
US HAZARDS OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST MARCH 08 2018  
 
SYNOPSIS: A SURFACE LOW IS FORECAST TO TRACK EAST FROM THE TENNESSEE VALLEY TO  
THE SOUTHERN MID-ATLANTIC ON MARCH 11. THIS SURFACE LOW IS EXPECTED TO  
STRENGTHEN AS IT MOVES NORTH OFFSHORE OF NEW ENGLAND ON MARCH 12 AND 13. AN  
AREA OF MID-LEVEL LOW PRESSURE IS EXPECTED TO SHIFT FROM THE EAST PACIFIC TO  
THE WESTERN U.S. LATER NEXT WEEK. AN AREA OF MID-LEVEL HIGH PRESSURE IS  
FORECAST TO BUILD OVER THE NORTH PACIFIC AND SOUTHWEST MAINLAND ALASKA DURING  
THE NEXT TWO WEEKS.  
 
HAZARDS  
 
HEAVY SNOW FOR THE HIGHER ELEVATIONS OF THE CENTRAL AND SOUTHERN APPALACHIANS  
AND PARTS OF THE MID-ATLANTIC, SUN-MON MORNING, MAR 11-12.  
 
HEAVY SNOW FOR PARTS OF THE NORTHEAST, MON-TUES, MAR 12-13.  
 
HIGH WINDS FOR PARTS OF THE NORTHEAST, MON-TUE, MAR 12-13.  
 
MUCH BELOW-NORMAL TEMPERATURES FOR PARTS OF THE SOUTHEAST AND MID-ATLANTIC,  
WED-THU, MAR 14-15.  
 
HEAVY SNOW FOR THE SIERRA NEVADA MOUNTAINS OF CALIFORNIA, TUE-THU, MAR 13-15.  
 
HEAVY SNOW FOR PARTS OF UTAH, THU, MAR 15.  
 
HIGH WINDS FOR THE SOUTHWEST AND SOUTHERN HIGH PLAINS, THU-FRI, MAR 15-16.  
 
FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE LOWER AND MIDDLE  
MISSISSIPPI VALLEY, NORTHEAST TEXAS, AND THE MIDWEST.  
 
A SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR PARTS OF THE EASTERN U.S.,  
FRI, MAR 16.  
 
A SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR PARTS OF THE NORTHERN GREAT  
PLAINS, SUN-THU, MAR 18-22.  
 
A SLIGHT TO MODERATE RISK OF HEAVY PRECIPITATION FOR PARTS OF THE WESTERN U.S.,  
FRI-SUN, MAR 16-18.  
 
SEVERE DROUGHT ACROSS PARTS OF CALIFORNIA, THE SOUTHWEST, GREAT PLAINS, AND  
SOUTHEAST GEORGIA.  
 
DETAILED SUMMARY  
 
FOR SUNDAY MARCH 11 - THURSDAY MARCH 15: THE RISK OF A THIRD MAJOR EAST COAST  
STORM THIS MONTH CONTINUES BASED ON THE ESTABLISHED LONGWAVE PATTERN BUT  
FORECAST CONFIDENCE IS LOW DUE TO LARGE DIFFERENCES AMONG DETERMINISTIC MODEL  
SOLUTIONS. THE GFS MODEL REMAINS THE MOST BULLISH ON THE POTENTIAL FOR A LATE  
SEASON WINTER STORM TO AFFECT THE MID-ATLANTIC, BEGINNING ON MARCH 11. DESPITE  
REASONABLY GOOD CONTINUITY AMONG THE GFS MODEL RUNS, THE DETERMINISTIC ECMWF  
MODEL RUNS, INCLUDING 12Z ON MAR 8, INDICATES A MUCH WEAKER AND SUPPRESSED  
SURFACE LOW WITH LITTLE IF ANY PRECIPITATION ACROSS THE MID-ATLANTIC. DUE TO  
LARGE DIFFERENCES BETWEEN THE GFS AND ECMWF DETERMINISTIC MODEL RUNS AT THIS  
FORECAST TIME LEAD, THE HEAVY SNOW HAZARD IS BASED ON PRECIPITATION AMOUNTS  
(0.5 INCH OR MORE) FROM THE 0Z/6Z GFS AND 0Z ECMWF ENSEMBLE MEANS AND PREDICTED  
THERMAL PROFILES. HEAVY SNOW (3 TO 6 INCHES, LOCALLY MORE) IS MOST LIKELY  
ACROSS THE HIGHER ELEVATIONS OF THE CENTRAL AND SOUTHERN APPALACHIANS ALONG  
WITH THE FOOTHILLS OF NORTH CAROLINA AND VIRGINIA ON MARCH 11 AND ENDING EARLY  
ON MARCH 12.  
 
A STRENGTHENING LOW PRESSURE SYSTEM OFFSHORE OF NEW ENGLAND IS EXPECTED TO  
BRING ANOTHER ROUND OF HEAVY SNOW AND HIGH WINDS TO PARTS OF THE NORTHEAST ON  
MARCH 12 AND CONTINUING ACROSS NORTHERN NEW ENGLAND THROUGH MARCH 13.  
 
IN THE WAKE OF THE EAST COAST STORM, SURFACE HIGH PRESSURE IS FORECAST TO BUILD  
OVER THE SOUTHEAST AND RESULT IN MINIMUM TEMPERATURES NEAR FREEZING ON MARCH 14  
AND 15. A MUCH BELOW-NORMAL TEMPERATURE HAZARD IS POSTED FOR AREAS WHERE A  
FREEZE COULD DAMAGE EARLY SPRING VEGETATION, INCLUDING BLOOMING PEACH TREES.  
 
HEAVY SNOW (6 INCHES OR MORE PER 24 HOURS) REMAINS LIKELY FOR THE SIERRA NEVADA  
MOUNTAINS OF CALIFORNIA FROM MARCH 13 THROUGH AT LEAST THE 15 AS AN AMPLIFIED  
500-HPA TROUGH MOVES INLAND FROM THE EAST PACIFIC. HEAVY SNOW (6 INCHES OR  
MORE) IS EXPECTED TO ADVANCE EAST TO PARTS OF UTAH BY MARCH 15.  
 
HIGH WINDS (GUSTS ABOVE 40 KNOTS) ARE LIKELY TO ACCOMPANY THE MID-LEVEL TROUGH  
AS IT PROGRESSES EAST TO THE SOUTHWESTERN U.S. AND SOUTHERN HIGH PLAINS BY  
MARCH 15. THE HIGH WINDS COULD TRIGGER A DUST STORM ACROSS THE DROUGHT PARCHED  
SOUTHERN HIGH PLAINS.  
 
WIDESPREAD MODERATE TO MAJOR FLOODING CONTINUES ALONG THE SOUTHERN THIRD OF THE  
MISSISSIPPI RIVER AND LOWER OHIO RIVER AND MANY OF THE TRIBUTARIES. FLOOD  
LEVELS ALONG THE LOWER MISSISSIPPI RIVER ARE FORECAST TO CONTINUE TO INCREASE  
THROUGH NEXT WEEK AND MAY EXCEED MAJOR FLOOD STAGE.  
 
FOR FRIDAY MARCH 16 - THURSDAY MARCH 22: STRONG COLD AIR ADVECTION IS EXPECTED  
ACROSS THE EASTERN U.S. NEXT WEEK, BEHIND THE STRENGTHENING LOW PRESSURE SYSTEM  
OVER THE CANADIAN MARITIMES. BELOW-NORMAL TEMPERATURES ARE FORECAST TO PERSIST  
THROUGH DAY 8 IN THIS REGION. A SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES  
IS POSTED FOR AREAS OF THE EASTERN U.S. WHERE THE GEFS TEMPERATURE TOOL  
INDICATES THAT MINIMUM TEMPERATURES HAVE A 20 TO 40 PERCENT OF FALLING BELOW  
THE 15TH PERCENTILE COMPARED TO CLIMATOLOGY AND NEAR TO BELOW FREEZING. THE  
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES POSTED FOR THE NORTHERN GREAT  
PLAINS FROM MARCH 18 TO 22 IS CONSISTENT WITH THE BUILDING RIDGE OVER THE NORTH  
PACIFIC.  
 
THE AMPLIFIED UPPER-LEVEL TROUGH ENTERING THE WESTERN U.S. DURING MID-MARCH  
SUPPORTS A SLIGHT TO MODERATE RISK OF HEAVY PRECIPITATION FROM MARCH 16 TO 18.  
THE MAJOR IMPACT ASSOCIATED WITH THIS PATTERN WOULD LIKELY BE HEAVY SNOW AT THE  
HIGHER ELEVATIONS ACROSS THE FOUR CORNERS REGION AND CENTRAL ROCKIES. ALSO,  
THIS PATTERN FAVORS HIGH WINDS (GUSTS ABOVE 40 KNOTS) AND THE INCREASED RISK OF  
DUST STORMS AND WILDFIRE DANGER ACROSS THE SOUTHWEST AND SOUTHERN HIGH PLAINS  
THROUGH AT LEAST MARCH 16.  
 
A DEVELOPING UPPER-LEVEL TROUGH (RIDGE) OVER THE BERING SEA (NORTH PACIFIC) AND  
ENHANCED ONSHORE FLOW ARE EXPECTED TO INCREASE THE RISK OF HIGH SURF/COASTAL  
FLOODING ALONG THE SOUTHWEST ALASKA COAST WHERE SEA ICE IS LOW.  
 
THE U.S. DROUGHT MONITOR, VALID ON MARCH 6, 2018 INDICATES AN INCREASE IN THE  
COVERAGE OF SEVERE TO EXCEPTIONAL DROUGHT (D2-D4) FROM 14.31% LAST WEEK TO  
15.50% THIS WEEK. SEVERE DROUGHT CONTINUES TO EXPAND ACROSS THE SOUTHERN HIGH  
PLAINS AND A SMALL AREA OF SEVERE DROUGHT IS CURRENTLY DESIGNATED FOR SOUTHEAST  
GEORGIA.  
 
FORECASTER: BRAD PUGH  
 

 
 
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