The National Weather Service forecasters in Sterling, Va. have posted winter storm warnings for our region as snow approaches from the Midwest. It's not a killer storm. We're talking 3 to 5 inches by morning at BWI, with 2 to 4 more during the day Friday - 5 to 9 total. Here's the forecast. But it's likely enough to disrupt everyone's routines tomorrow.

There's also still a chance that things could get rapidly much worse. The Midwest storm is only part of the setup. That storm is moving in parallel with another low-pressure center that's forming to our south. If the two merge, and tap into moisture and energy from the ocean, it could deliver much heavier snow for someone - maybe us, maybe to our north and east. Here's how AccuWeather sees it.

At any rate, here's the current NWS winter storm warning:

"THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS ISSUED A
WINTER STORM WARNING...WHICH IS IN EFFECT FROM 6 PM THIS EVENING
TO 12 PM EST FRIDAY. THE WINTER STORM WATCH IS NO LONGER IN
EFFECT.

"A WINTER STORM IS CURRENTLY TAKING SHAPE ACROSS THE OHIO VALLEY...AND
IS FORECAST TO ADVANCE INTO OUR REGION THIS EVENING. THIS STORM
HAS A POTENTIAL OF PRODUCING A MIXED BAG OF SNOW...SLEET AND
FREEZING RAIN ACROSS THE DC AND BALTIMORE METRO AREAS. TOTAL
ACCUMULATIONS OF SNOW AND SLEET OF 3 TO 6 INCHES ARE EXPECTED BY FRIDAY
MORNING.

"A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW...
SLEET...AND ICE ARE EXPECTED. THIS WILL MAKE TRAVEL VERY
HAZARDOUS. IF YOU MUST TRAVEL...KEEP AN EXTRA
FLASHLIGHT...FOOD...AND WATER IN YOUR VEHICLE IN CASE OF AN
EMERGENCY. STAY TUNED NOAA WEATHER RADIO OR LOCAL MEDIA FOR
UPDATES TO THE FORECAST."

OK. That's the warning for our area. The curious thing about it is that the warning covers Sterling's forecast area, which stops at the Mason Dixon Line. Just above that line, just north of Baltimore Harford, Cecil, Carroll and Frederick counties in Maryland, the warning is a "heavy snow warning." The NWS forecast office for those areas - in State College, Pa. - is looking for up to a foot of snow central Pennsylvania, including Adams, York and Lancaster counties, just north of the Mason Dixon Line. Here's how their warning reads:

"THE SNOW WILL FALL HEAVILY AT TIMES THROUGH FRIDAY MORNING.

"BY SUNRISE ON FRIDAY...5 TO 8 INCHES OF A FLUFFY AND DRY SNOW WILL
COVER MOST OF CENTRAL PENNSYLVANIA...WITH 8 TO 10 INCHES POSSIBLE
ON THE RIDGES.

"THE SNOW WILL TAPER OFF TO SCATTERED SNOW SHOWERS BEFORE NOON.
ADDITIONAL ACCUMULATIONS FRIDAY MORNING COULD PUSH THE TOTALS CLOSE
TO OR EVEN OVER ONE FOOT."

The more time you spend looking at these watches and warnings, the more you realize that the geo-political boundaries they use don't always make sense. They're convenient, maybe even necessary. But they're not always logical. I mean, does this map make sense?