A Winter Storm Watch is issued by the National Weather Service of the United States when there is a potential for heavy snow or significant ice accumulations. The watch is usually issued 12 to 48 hours before the storm's arrival in the area. As is true with a Winter Weather Advisory, the criteria for this watch can vary from place to place. If strong winds are expected with reduced visibilities, a winter storm watch may be upgraded to a Blizzard Watch. A Winter Storm Watch is different from a Winter Weather Advisory in the sense that a Winter Weather Advisory is meant to advise those of the conditions that currently exist outside, while a Winter Storm Watch simply means that there is a chance of a storm coming. A Winter Storm Watch will become a Winter Storm Warning when the storm is in happening or about to happen. Winter Storm Watches are given so that communities can prepare in the chance that the winter storm does in fact hit. Winter storm watches often go in place when there is a chance between 50-80% of the storm occurring.
Example of a Winter Storm Watch
918 WWUS43 KLOT 301126 WSWLOT URGENT - WINTER WEATHER MESSAGE NATIONAL WEATHER SERVICE CHICAGO IL 526 AM CST SUN JAN 30 2011 ...SIGNIFICANT WINTER STORM TO AFFECT THE SOUTHERN GREAT LAKES REGION TUESDAY INTO WEDNESDAY... .A PERIOD OF WINTRY WEATHER IS EXPECTED TO AFFECT NORTHERN ILLINOIS AND NORTHWEST INDIANA THE FIRST HALF OF THE WORK WEEK. SIGNIFICANT AMOUNTS OF SNOW ARE EXPECTED TO ACCUMULATE BETWEEN MONDAY MORNING AND WEDNESDAY EVENING...WITH SNOWFALL TOTALS OF 12 OR MORE INCHES QUITE POSSIBLE IN NORTHEAST ILLINOIS AND NORTHWEST INDIANA BY WEDNESDAY NIGHT. THE FIRST ACCUMULATING SNOW IS EXPECTED TO SPREAD ACROSS THE AREA MONDAY MORNING. SNOWFALL IS EXPECTED TO INTENSIFY FOR MONDAY AFTERNOON AND EVENING...THEN LIGHTEN UP AGAIN LATE MONDAY NIGHT INTO TUESDAY MORNING. ACCUMULATIONS OF 2 TO 4 INCHES CAN BE EXPECTED BY MIDDAY TUESDAY. HOWEVER...THIS WILL ONLY BE THE PRELIMINARY ROUND OF SNOW AS AN INTENSE WINTER STORM WILL BE TRACKING FROM ARKANSAS NORTHEASTWARD UP THE OHIO VALLEY TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING. THIS STORM SYSTEM WILL LIKELY PRODUCE AN BAND OF VERY HEAVY SNOW ALONG AND TO THE NORTH OF ITS TRACK. THIS PUTS THE ENTIRE AREA UNDER THE GUN FOR A MAJOR SNOWFALL EVENT. AS THE LOW PRESSURE CENTER REACHES THE UPPER OHIO VALLEY BY LATE WEDNESDAY MORNING A STRONG FLOW OF COLD AIR WILL BE MOVING ACROSS SOUTHERN LAKE MICHIGAN...WITH LAKE EFFECT SNOW DEVELOPING ON THE ILLINOIS SIDE OF THE LAKE. AS THE DAY PROGRESSES WEDNESDAY THE STRONG LOW LEVEL FLOW WILL BECOME MORE NORTHERLY AND THE LAKE EFFECT SNOW WILL SHIFT TO FAR NORTHWEST INDIANA. BY LATER WEDNESDAY THE SNOW FROM THE DEPARTING WINTER STORM WILL BE WINDING DOWN ACROSS THE AREA BUT A BAND OF SIGNIFICANT LAKE EFFECT SNOW IS EXPECTED IN NORTHWEST INDIANA WHERE SEVERAL ADDITIONAL INCHES OF SNOW ARE POSSIBLE BEFORE THE LAKE EFFECT SHIFTS FURTHER OFF TO THE EAST INTO SOUTHWESTERN LOWER MICHIGAN AND NORTH CENTRAL INDIANA. BETWEEN THE INITIAL LIGHTER SNOW MONDAY INTO TUESDAY MORNING...THE HEAVY SNOWFALL FROM THE MAJOR WINTER STORM DURING TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING...AND THE INCREASINGLY INTENSE LAKE EFFECT SNOW DEVELOPING DURING WEDNESDAY...A FOOT OR MORE OF SNOW WILL NOT BE UNCOMMON OVER MUCH OF NORTHEAST ILLINOIS AND FAR NORTHWEST INDIANA. THE STORM SYSTEM WILL BE AFFECTING A LARGE PORTION OF THE SOUTHERN GREAT LAKES...MIDWEST AND OHIO VALLEY REGIONS. ANYONE WITH TRAVEL PLANS TUESDAY AND WEDNESDAY...INCLUDING THOSE TRAVELING THROUGH CHICAGO OHARE AND MIDWAY AIRPORTS...SHOULD CONTINUE TO MONITOR LATER FORECASTS REGARDING THE DEVELOPMENT OF THIS WINTER STORM. ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019- 301930- /O.NEW.KLOT.WS.A.0001.110201T1800Z-110203T0000Z/ WINNEBAGO-BOONE-MCHENRY-LAKE IL-OGLE-LEE-DE KALB-KANE-DUPAGE-COOK- LA SALLE-KENDALL-GRUNDY-WILL-KANKAKEE-LIVINGSTON-IROQUOIS-FORD- LAKE IN-PORTER-NEWTON-JASPER-BENTON- INCLUDING THE CITIES OF...ROCKFORD...BELVIDERE...WOODSTOCK... WAUKEGAN...OREGON...DIXON...DEKALB...AURORA...WHEATON...CHICAGO... OTTAWA...OSWEGO...MORRIS...JOLIET...KANKAKEE...PONTIAC... WATSEKA...PAXTON...GARY...VALPARAISO...MOROCCO...RENSSELAER... FOWLER 526 AM CST SUN JAN 30 2011 /626 AM EST SUN JAN 30 2011/ ...WINTER STORM WATCH IN EFFECT FROM TUESDAY AFTERNOON THROUGH WEDNESDAY AFTERNOON... THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A WINTER STORM WATCH...WHICH IS IN EFFECT FROM TUESDAY AFTERNOON THROUGH WEDNESDAY AFTERNOON. * TIMING...HEAVY SNOWFALL WILL SPREAD NORTHEASTWARD ACROSS THE AREA MIDDAY WEDNESDAY AND CONTINUE THROUGH TUESDAY NIGHT. AS THE SNOWFALL FROM THE STORM SYSTEM STARTS TO WIND DOWN DURING WEDNESDAY MORNING AND EARLY AFTERNOON...LAKE EFFECT SNOW WILL HAVE DEVELOPED ON THE ILLINOIS SIDE OF THE LAKE. INCREASINGLY HEAVY AND MORE CONCENTRATED LAKE EFFECT SNOW WILL SHIFT INTO FAR NORTHWEST INDIANA DURING WEDNESDAY AFTERNOON AND PERSIST INTO WEDNESDAY EVENING BEFORE SHIFTING FURTHER OFF TO THE EAST INTO SOUTHWEST LOWER MICHIGAN AND NORTH CENTRAL INDIANA. * ACCUMULATIONS...TOTAL ACCUMULATIONS FROM MONDAY MORNING THROUGH WEDNESDAY EVENING ARE EXPECTED TO BE IN EXCESS OF 8 INCHES IN NORTH CENTRAL ILLINOIS...AND IN EXCESS OF 12 INCHES OVER NORTHEAST AND EAST CENTRAL ILLINOIS...AS WELL AS NORTHWEST INDIANA. LOCAL AMOUNTS IN EXCESS OF 18 INCHES ARE POSSIBLE IN FAR NORTHWEST INDIANA...DEPENDING ON EXACTLY WHERE THE LAKE EFFECT SNOW BAND SETS UP AND HOW PERSISTENT IT IS OVER ANY ONE LOCATION. * HAZARDS...HEAVY SNOWFALL AS WELL AS BLOWING AND DRIFTING SNOW. * IMPACTS...VERY DIFFICULT TO NEAR IMPOSSIBLE TRAVEL CONDITIONS AS SNOW WILL BE ACCUMULATING AT A RAPID RATE DURING THE PEAK OF THE SNOW STORM TUESDAY AFTERNOON AND NIGHT. HEAVY LAKE EFFECT SNOW IN NORTHWEST INDIANA LATER WEDNESDAY AND WEDNESDAY EVENING WILL CONTINUE TO HAMPER TRAVEL THERE. PRECAUTIONARY/PREPAREDNESS ACTIONS... A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR SIGNIFICANT SNOW...SLEET...OR ICE ACCUMULATIONS THAT MAY IMPACT TRAVEL. CONTINUE TO MONITOR THE LATEST FORECASTS. && $$ <ref>{{Cite web|url=http://www.weather.gov/lot/2015_Feb01_Snow|title=Historic Winter Storm of January 31-February 2, 2015|last=Service|first=US Department of Commerce, NOAA, National Weather|website=www.weather.gov|language=EN-US|access-date=2016-10-27}}</ref>References
Winter storm watch Wikipedia(Text) CC BY-SA