We Could See More Snow Than First Thought, says Weather Service

THE LOW WILL PASS BY TO OUR SOUTH TODAY BEFORE RAPIDLY INTENSIFYING TONIGHT AS IT MOVES OUT TO SEA. FORCING FROM THE SURFACE LOW AS WELL AS THE UPPER-LEVEL DISTURBANCE WILL CAUSE PRECIPITATION TO BREAK OUT OVER THE AREA TODAY…SPREADING FROM WEST TO EAST ACROSS THE AREA THIS MORNING. VERY COLD AIR WILL FILTER IN FROM THE NORTH DURING THIS TIME…CAUSING THE PTYPE TO BE SNOW ACROSS ALL LOCATIONS.

THE COMBINATIONS OF HIGH SNOW TO LIQUID RATIOS…OVERRUNNING…AND FRONTOGENETICAL FORCING WILL ALL LINE UP OVER THE AREA CAUSING HEAVY SNOW TO IMPACT THE REGION. A WINTER STORM WARNING REMAINS IN EFFECT FOR THE ENTIRE AREA TODAY THROUGH THIS EVENING. SNOWFALL ACCUMULATIONS AROUND SIX TO TEN INCHES ARE EXPECTED WITH THE HIGHEST AMOUNTS MOST LIKELY IN THE POTOMAC HIGHLANDS AS WELL AS NORTHERN MARYLAND AND NORTHERN VIRGINIA. LOCALLY HIGHER SNOWFALL TOTALS ARE POSSIBLE DUE TO THE BANDING NATURE OF THE PRECIPITATION.

DRIER AIR WILL MOVE IN TONIGHT AS THE LOW PULLS AWAY FROM THE AREA. SNOW WILL END FROM WEST TO EAST THIS EVENING…BUT IT WILL TURN OUT QUITE WINDY DUE TO A STRONG PRESSURE GRADIENT BETWEEN THE DEEPENING LOW AND ARCTIC HIGH PRESSURE OVER THE MIDWEST. BLOWING AND DRIFTING SNOW WILL CONTINUE THROUGH TONIGHT EVEN AFTER THE SNOW ENDS.

THE NORTHWEST WINDS WILL USHER IN BITTERLY COLD AIR…CAUSING MIN TEMPS TO RANGE FROM BELOW ZERO IN THE MOUNTAINS TO THE SINGLE DIGITS ELSEWHERE. WIND CHILL VALUES WILL DROP BELOW ZERO TONIGHT WITH THE COLDEST SPOTS IN THE MOUNTAINS. A WIND CHILL WARNING IS IN EFFECT TONIGHT FOR THE POTOMAC HIGHLANDS AND A WIND CHILL ADVISORY IS IN EFFECT ELSEWHERE.

And after all of this snow ends tonight, bitterly cold air will filter in behind it, and that prompted the weather service to issue a wind chill advisory as temperatures could feel like they are 15 degrees below zero tonight.

WIND CHILL…BETWEEN 5 AND 15 DEGREES BELOW ZERO TONIGHT THROUG WEDNESDAY MORNING.

* TEMPERATURES…DROPPING INTO THE 20S THIS MORNING…THEN FALLING INTO THE TEENS THIS AFTERNOON AND EVENING. LOW TEMPERATURES TONIGHT WILL BE IN THE SINGLE DIGITS. HIGH TEMPERATURE WEDNESDAY WILL BE IN THE TEENS.

* WINDS…NORTHEAST 5 TO 10 MPH…INCREASING TO 10 TO 20 MPH WITH GUSTS AROUND 30 MPH THIS AFTERNOON. WINDS WILL BECOME NORTHWEST TONIGHT THROUGH WEDNESDAY MORNING AT 15 TO 25 MPH WITH GUSTS UP TO 40 MPH.

* IMPACTS…ROADS WILL BE SNOW COVERED AND SLIPPERY. THE COMBINATION OF SNOW AND BLOWING SNOW WILL REDUCE VISIBILITY TO BELOW ONE-HALF MILE AT TIMES. TRAVELING WILL BECOME DANGEROUS TODAY.

THE MORNING COMMUTE MAY BE IMPACTED BY THE SNOW…BUT SIGNIFICANT IMPACT IS EXPECTED FOR THE AFTERNOON AND EVENING COMMUTE. DANGEROUSLY LOW WIND CHILLS TONIGHT THROUGH WEDNESDAy MORNING MAY LEAD TO HYPOTHERMIA OR FROST BITE ON EXPOSED SKIN.