Winter Weather Advisory Changes

Winter weather is on our doorstep. Temperatures have turned sharply colder and a few flurries and snow showers have fallen around Baltimore. Significant snows have fallen in the mountains.

I wanted to pass along a word about some changes the National Weather Service is making regarding their Winter Weather Advisories.

The threshold for issuance of various advisories on winter weather hazards has been lowered for specific time periods in the Baltimore and Washington metropolitan areas. Highway travel in the metro areas has become much more congested in recent years and it has become evident that even the slightest snow or ice accumulations can cause major traffic headaches. The folowing information was released by the National Weather Service explaining the new guidelines.

PUBLIC INFORMATION STATEMENT 

NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC

1119 AM EST THU NOV 13 2008


…THE NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON WEATHER FORECAST OFFICE WILL MODIFY LOCAL WINTER WEATHER ADVISORY THRESHOLDS EFFECTIVE 10:00 AM EST NOVEMBER 17 2008…


A WINTER WEATHER ADVISORY IS ISSUED FOR HAZARDOUS WINTER WEATHER THAT CAUSES SIGNIFICANT INCONVENIENCES…AND IF CAUTION IS NOT EXERCISED…COULD LEAD TO LIFE-THREATENING SITUATIONS. IN PAST COLD WEATHER SEASONS…WINTER WEATHER ADVISORIES WERE ISSUED WHEN FORECASTERS HAD A 80 PERCENT OR GREATER CONFIDENCE OF AT LEAST 2 TO LESS THAN 5 INCHES OF SNOW AND/OR SLEET WITHIN A 12 HOUR PERIOD.

 

STARTING THIS COLD WEATHER SEASON 2008-2009…THE NATIONAL WEATHER SERVICE BALTIMORE / WASHINGTON WEATHER FORECAST OFFICE WILL EXPAND THE WINTER WEATHER ADVISORY CRITERIA LISTED ABOVE FOR SPECIFIC HIGH-TRAVEL AREAS DURING RUSH HOUR PERIODS BASED ON ADVERSE PUBLIC-IMPACT. IN ADDITION TO THE CRITERIA LISTED IN THE PREVIOUS PARAGRAPH…A WINTER WEATHER ADVISORY WILL NOW BE ISSUED WHEN FORECASTER CONFIDENCE IS 60 PERCENT OR HIGHER FOR AT LEAST 1 INCH TO LESS THAN 2 INCHES OF SNOW AND/OR SLEET THAT IS FORECAST TO ACCUMULATE DURING WEEKDAY MORNING OR EVENING RUSH HOURS. WEEKDAY RUSH HOURS ARE DEFINED AS MONDAY THROUGH FRIDAY /EXCLUDING FEDERAL HOLIDAYS/ FROM 4:00 AM TO 9:00 AM AND 2:00 PM TO 7:00 PM.

The National Weather Service map below defines the areas affected by these new guidelines.

wsy_threshold

 

It really comes down to the likelihood that there will be more winter weather advisories this season, not necessarily because of more storm activity but because of the impact even minor storms have on our crowded highways.

John Collins

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