310  
FXUS02 KWBC 241438  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
937 AM EST SUN FEB 24 2019  
 
VALID 12Z WED FEB 27 2019 - 12Z SUN MAR 03 2019  
   
..PATTERN OVERVIEW
 
 
A STRONG MID-LEVEL POSITIVE ANOMALY STARTING IN AK WILL DRIFT  
NORTHEAST INTO THE CANADIAN ARCHIPELAGO, FORCING CHANGES  
DOWNSTREAM, SUCH AS A CONSOLIDATING MID-LEVEL VORTEX IN SOUTHEAST  
CANADA WHICH, SOONER OR LATER, SHOULD SETTLE INTO THE LABRADOR SEA  
EARLY NEXT WEEK. OVERALL, THIS MAINTAINS A ZONAL-ISH FLOW THROUGH  
THE MEDIUM RANGE PERIOD.  
 
WHILE ZONAL FLOW CAN LEAD TO MILDER THAN CLIMATOLOGICAL CONDITIONS  
ACROSS THE LOWER 48, BELOW AVERAGE MID-LEVEL HEIGHTS NEAR AND WEST  
OF A COLD LOW DROPPED SOUTHEAST INTO SOUTHEAST CANADA CONTINUE  
OVER THE NORTHERN PLAINS, PROMISING CONTINUED COLDER THAN AVERAGE  
TEMPERATURES FOR THE REMAINDER OF FEBRUARY INTO EARLY MARCH. ANY  
MILDNESS SHOULD BE GENERALLY CONSTRAINED ACROSS THE SOUTHERN TIER  
OF THE COUNTRY.  
 
   
..MODEL PREFERENCES
 
 
THE GUIDANCE SHOWED VERY GOOD AGREEMENT OVERALL. FOR THE  
PRESSURES, WINDS, AND 500 HPA HEIGHTS, USED A BLEND OF THE 00Z  
UKMET, 00Z CANADIAN, 00Z GFS, AND 00Z ECMWF WHICH INCORPORATES  
SLOWLY INCREASING PERCENTAGES OF THE 00Z BIAS-CORRECTED NAEFS MEAN  
AND 00Z ECMWF ENSEMBLE MEAN WITH TIME. THE REMAINDER OF THE  
WEATHER GRIDS, INCLUDING QPF, USED A MORE EVEN BLEND OF THE  
DETERMINISTIC AND ENSEMBLE MEAN GUIDANCE.  
 
   
..WEATHER HIGHLIGHTS/HAZARDS
 
 
OVER THE WEST, EXPECT AREAS OF ENHANCED PRECIPITATION (RAIN AND  
HIGHER ELEVATION SNOW) TO EXTEND FROM CALIFORNIA THROUGH THE GREAT  
BASIN AND INTO THE NORTH-CENTRAL/CENTRAL ROCKIES. THERE WILL BE  
TWO MAIN SYSTEMS OF NOTE, ONE ARRIVING AROUND THE START OF THE  
PERIOD AND BRINGING RAIN/SNOW DURING WED-THU AND THE NEXT MOST  
LIKELY SPREADING MOISTURE ACROSS THE REGION DURING THE WEEKEND.  
THE SECOND SYSTEM'S MOISTURE AXIS SHOULD BE SOMEWHAT SOUTHWARD OF  
THE FIRST. HIGHEST TOTALS DURING THE PERIOD SHOULD BE OVER THE  
SIERRA NEVADA RANGE.  
 
AROUND MIDWEEK MODEST SHORTWAVE ENERGY/SURFACE WAVINESS MAY BRING  
AN AREA OF MOSTLY LIGHT SNOW ACROSS THE NORTHEASTERN QUADRANT OF  
THE LOWER 48. ANOTHER SMALL AREA OF RAIN/SNOW MAY CROSS PARTS OF  
THE OHIO VALLEY/MID-ATLANTIC LATER IN THE WEEK. THEN GUIDANCE IS  
STARTING TO SHOW MORE SIMILAR IDEAS FOR POTENTIALLY STRONG SURFACE  
DEVELOPMENT WITH LOW PRESSURE REACHING THE GREAT LAKES AROUND  
SATURDAY MORNING AND CONTINUING NORTHEASTWARD THEREAFTER. HIGHEST  
SNOW POTENTIAL WOULD EXTEND ACROSS PARTS OF THE MIDWEST INTO THE  
NORTHWESTERN GREAT LAKES WITH MEANINGFUL SNOWFALL ALSO POSSIBLE  
OVER NEW ENGLAND. EXPECT RAIN FARTHER SOUTH AND SOME POCKETS OF  
LOCALLY MODERATE-HEAVY ACTIVITY MAY BE POSSIBLE. SLIGHTLY BETTER  
POTENTIAL FOR HIGHEST TOTALS WILL BE OVER THE GULF COAST STATES  
BUT RELATIVE MAXIMA MAY BE POSSIBLE OVER OTHER PARTS OF THE EAST  
AS WELL.  
 
CONTINUE TO EXPECT VERY COLD TEMPERATURES CENTERED OVER AND NEAR  
THE NORTHERN HALF OF THE PLAINS. WED-FRI READINGS WILL BE EXTREME  
ENOUGH AT 10-30F BELOW NORMAL BUT A STRONGER SURGE OF COLD AIR FRI  
INTO THE WEEKEND COULD BRING SOME AREAS TO 30-40F BELOW NORMAL  
WHILE LESS EXTREME COLD ANOMALIES SPREAD FARTHER SOUTH AND EAST.  
MEANWHILE PACIFIC FLOW WILL KEEP MIN TEMPERATURES IN PARTICULAR  
ABOVE NORMAL OVER THE SOUTHERN 2/3 OF THE WEST. THE SOUTHERN TIER  
STATES SHOULD SEE ABOVE NORMAL TEMPERATURES ON AVERAGE BUT WITH A  
COOLING TREND NEXT WEEKEND.  
 
ROTH/REINHART/RAUSCH  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION AND WINTER WEATHER OUTLOOK  
PROBABILITIES ARE FOUND AT:  
 
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  

 
 
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