Friday January 7, 2011
Forecaster: James Spann
MAJOR WINTER STORM POSSIBLE SUNDAY AND MONDAY: Parameters are coming together for the potential for very significant winter weather issues for Alabama in about 48 hours. But, before we get there…
TODAY AND TOMORROW: The weather will be generally quiet across Alabama through tomorrow. For the I-20 corridor, we expect ample sunshine, with a high in the low 50s today, followed by mid 40s tomorrow as colder air begins to drop into the state. We need to mention some risk of show flurries or snow showers across the northeast corner of the state at times today or tonight, but the bulk of that precipitation is expected to be up in Tennessee.
Clouds will thicken tomorrow night in advance of our developing winter weather system.
SUNDAY/MONDAY: A vigorous wave in the upper atmosphere will spin up a surface low in the Northwest Gulf of Mexico, which will move to the east/northeast through Monday. A shield of precipitation will move into Southwest Alabama Sunday morning, which could be in the form of freezing rain or sleet at the onset. As the precipitation moves north, it is expected to be mostly snow across the northern third of the state, with a wintry mix of snow and freezing rain over the North-Central Counties. It looks like the heaviest precipitation will come Sunday night, with potential for heavy snow over North Alabama, and some significant icing over the central counties. Then, during the day Monday, the precipitation will slowly taper off as the low weakens and moves northeast.
The National Weather Service will be issuing a winter storm watch for much of North and Central Alabama early this morning. Here is a breakdown of our accumulation forecast
THE TENNESSEE VALLEY: We are projecting 5 to 10 inches of snow for the northern third of the state, generally north of U.S. 278, or north of a line from Hamilton to Cullman to Gadsden. Some of the cities in this region include Decatur, Muscle Shoals, Athens, Huntsville, Scottsboro, and Boaz. Within this area, there will be about a 30 to 40 mile wide zone of heavy snow, where we expect 7 to 10 inches. Other areas will see 5 to 7 inches, most likely.
NORTH-CENTRAL ALABAMA: For the I-20 corridor (Tuscaloosa, Birmingham, Anniston), we are forecasting 2 to 5 inches of snow, with potential for periods of freezing rain, which could lead to some significant amounts ice accumulation on trees, power lines, and bridges. It remains to be seen if there will be enough ice for major power outages, but that possibility can’t be ruled out completely. Freezing rain is liquid precipitation that falls when surface temperatures are below freezing; this tends to coat everything with ice. This is clearly the most challenging part of this forecast.
U.S. 80 CORRIDOR: Some snow and ice is likely as far south as U.S. 80, or a line from Demopolis to Selma to Montgomery to Opelika. The accumulation will be lighter here, but icy spots are possible on bridges along with some light snow accumulation by Monday morning.
SOUTH ALABAMA: Mostly rain will fall south of U.S. 80, but there could be periods of sleet, and some freezing rain. Maybe even a few snow flakes. But, major problems for now are not expected over the southern half of Alabama from wintry precipitation.
TRAVEL: It is likely that travel across the northern half of Alabama will become difficult, if not impossible in areas, Sunday afternoon into Sunday night and Monday. We realize many are flying out of Birmingham headed to Auburn’s national championship game in Phoenix this weekend; be aware that major flight delays are possible Sunday and Monday due to ice and snow. This winter storm will also impact airports in Atlanta, Nashville, and Memphis.
BE WEATHER AWARE: Keep an eye for changes in our forecast as this system develops during the next 48 hours. With any winter weather event like this in Alabama, some people will receive snow than forecast, and others less. And, there is always a surprise or two. Stay tuned.
NEXT WEEK: Very cold air settles into the state early next week, and we will maintain a chance of lingering snow showers or flurries into Tuesday. Highs will be only in the 30s, with lows in the 20s. Major travel problems sure seem likely Monday morning, with some potential for improvement by Monday afternoon as temperatures ease above freezing. For now Wednesday and Thursday look dry with moderating temperatures.
LONG RANGE: Still some concern over very cold Arctic air that is expected to invade the continental U.S. in about 7 to 10 days; if the pattern we see on computer model output verifies, we could be dealing with record cold across the Deep South in the January 18-22 time frame.
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or 
