GOVERNOR BOB MCDONNELL HAS DECLARED THE WEEK DECEMBER 5 TO 11...2010
AS WINTER PREPAREDNESS WEEK IN VIRGINIA. THE NATIONAL WEATHER SERVICE
OFFICES SERVING VIRGINIA...IN COOPERATION WITH THE VIRGINIA
DEPARTMENT OF EMERGENCY MANAGEMENT...WILL SEND PUBLIC INFORMATION
STATEMENTS EACH DAY THROUGH SATURDAY AT APPROXIMATELY 11 AM.
THESE STATEMENTS WILL FOCUS ON DIFFERENT ASPECTS OF WINTER WEATHER 
...AND PREPAREDNESS ACTIONS THE PUBLIC SHOULD TAKE FOR THE UPCOMING WINTER SEASON.

...THE ALBERTA CLIPPER...WHAT?...WHERE?...WHY?...

DURING MOST WINTERS...A LARGE POLAR VORTEX ESTABLISHES ITSELF OVER
HUDSON BAY CANADA...AND EXTENDS ITS INFLUENCE SOUTHWARD INTO THE
CENTRAL AND EASTERN PARTS OF THE U.S. SMALLER SCALE LOW PRESSURE
AREAS BECOME EMBEDDED IN THE LARGE CIRCULATION AROUND THE POLAR
VORTEX AND DROP SOUTHEASTWARD INTO THE U.S. FROM THE CANADIAN
PRAIRIE PROVINCES OF ALBERTA AND SASKATCHEWAN.

APPROPRIATELY TERMED "ALBERTA CLIPPERS"...THESE FAST MOVING STORM
SYSTEMS USUALLY PRECEDE A SURGE OF COLD POLAR OR ARCTIC AIR...AND
CAN PRODUCE BURSTS OF SIGNIFICANT SNOW ALONG WITH STRONG WINDS. IN
MOST INSTANCES...ALBERTA CLIPPERS PRODUCE LIMITED PRECIPITATION IN
VIRGINIA DUE TO THEIR FAST MOVEMENT AND RESULTANT INABILITY TO TAP
MOISTURE FROM EITHER THE ATLANTIC OCEAN OR GULF OF MEXICO. WHEN
SNOW OCCURS WITH AN ALBERTA CLIPPER...IT IS USUALLY ON THE ORDER OF
A DUSTING TO FOUR INCHES...I.E. A "NUISANCE" SNOW.

HOWEVER...IF THE POLAR VORTEX IS STRONG ENOUGH...AND ITS INFLUENCE
EXTENDS SOUTHWARD INTO THE DEEP SOUTH...STRONG ALBERTA CLIPPERS CAN
BECOME MAJOR WEATHER EVENTS FOR VIRGINIA AND OTHER PARTS OF THE MID
ATLANTIC REGION. IN THESE SITUATIONS...THE ALBERTA CLIPPER TAPS
THE AVAILABLE MOISTURE SOURCES FROM THE ATLANTIC OCEAN AND GULF OF
MEXICO. THE SURFACE LOW REDEVELOPS AND INTENSIFIES NEAR THE MID OR
SOUTH ATLANTIC COAST...AND BECOMES A FULL BLOWN NOR'EASTER. THE
ENSUING NOR'EASTER SPREADS HEAVY SNOW...(SOMETIMES RAIN NEAR THE
COAST) AND STRONG WINDS UP THE EAST COAST...PRODUCING MAJOR TRAVEL
PROBLEMS.

ADDITIONAL INFORMATION ON WINTER WEATHER PREPAREDNESS CAN BE
OBTAINED ON-LINE THROUGH THE VIRGINIA DEPARTMENT OF EMERGENCY
MANAGEMENT HOME PAGE AT:

WWW.VAEMERGENCY.COM/THREATS/WINTER/INDEX.CFM

IN ADDITION...THE READY VIRGINIA WEB SITE HAS BEEN DEVELOPED 
TO AID VIRGINIANS IN THEIR OVERALL DISASTER PREPAREDNESS:

WWW.READYVIRGINIA.GOV...ENGLISH VERSION/
WWW.LISTOVIRGINIA.GOV...SPANISH VERSION/

UP-TO-DATE WEATHER INFORMATION IS ALSO AVAILABLE ON-LINE FROM THE
NATIONAL WEATHER SERVICE AT: WWW.WEATHER.GOV/BLACKSBURG.

THE NATIONAL WEATHER SERVICE WINTER WEATHER AWARENESS HOME PAGE IS:
WWW.NWS.NOAA.GOV/OM/WINTER/INDEX.SHTML