Another Nice Day
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After a beautiful day yesterday, Central Alabama is going to experience another gorgeous day with sunshine and temperatures in the middle 50s. Those temperatures are about 5 to 7 degrees below where we ought to be in late February. Our high should be about 61. But it will still be nice with the sunshine and light wind.
The next storm system in a long string of these will begin to impact us on Monday as clouds increase. The upper air system moves closer generating a surface low in the northwest Gulf of Mexico. The models are beginning to come together on the position of the low which is pretty close to a classic scenario for snow across the Southeast. But the area of best snow chances – or sweet spot – continues to be somewhat elusive.
These are the complicating factors for this event. The latest GFS run is just slightly slower than the previous run – not by much but just enough – so that we could see high temperatures once again climb into the 50s on Monday. This means more warmth to be overcome by the cold air advection. While the upper air temperature profile continues to support the idea of snow, there continues to be a substantial layer of warm air right next to the ground. While this warm layer is only a couple of thousand feet thick, it is certainly enough to melt a good deal of snow falling into it. So it really seems like the result is going to be a rain/snow mixture that might change over to mostly snow Tuesday as the moisture winds down. Add to these factors the fact that the warmth and sun of today and yesterday plus whatever sun we get Monday morning has certainly warmed the ground meaning that there is little chance any snow will stick.
I think the best chances for the rain/snow mix will come along a 100-mile band centered on and running just a little south of a line from Tuscaloosa to Birmingham to Jacksonville. Usually when we are just 36 hours from an event, we can get a pretty good handle on it. But please remember that the recipe for snow in the Southeast is a very exact one, so we’ve got to have all the necessary parameters come together in exactly the right proportion at exactly the right time. And that is not an excuse – that is the reason why snow forecasting here is tough.
The surface low zips over into the Southwest Atlantic on Wednesday bringing us out of the precipitation but keeping us chilly. We stay chilly on Thursday but by Friday a new trough to our west promises to build the ridge over the eastern half of the country returning Central Alabama to something close to typical temperatures by Saturday – that’s highs in the lower 60s.
That same trough is forecast to generate a strong surface low that will move toward Chicago and trail a cold front into the Southeast on Monday.
A quick peek into voodoo country continues to show an active weather pattern but with the main systems pulled slightly further north. This could mean the end to these Gulf low scenarios, but it’s voodoo so we’ll see.
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Thanks so much for staying with us. Be sure to check back over the next couple of days as we continue to watch and update information on the potential winter weather event for Monday night and Tuesday. I hope that you enjoy the day and Godspeed.
-Brian-
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February 28th, 2010 at 8:10 am
The models are looking GREAT. I’m very nervous about this “warm layer” though
February 28th, 2010 at 8:23 am
Forget it folks……….this one will be ALL RAIN. Bring on Spring
February 28th, 2010 at 8:25 am
Too warm, too warm, on and on. It is not going to snow this time. If it does, won’t stick.
February 28th, 2010 at 8:34 am
12Z NAM….a little colder at 48hr….WOO HOO !!!
February 28th, 2010 at 8:43 am
Get ready folks it is going to bad Monday night and Tuesday morning for sure all indications are that we are going to have some weather during that time. It will probably be a serious case of not unusual near spring weather.
lol
here in Vigo this morning,
low 26 at about 2:00am
current temp is 45
humidity is 49% (no fires)
pressure is 29.87
DP is 26
winds are 2mph with gust to 5mph from the West.
Looks like after this next event I will have time to get the porch built on the front of the “pre=manufactured” home and the ramp so that some of my friends with dificulty getting up steps can get in the house easier. This might include me if my knees don’t get better, might be the cold weather also.
I wouldn’t mind having one more little shot of snow but it isn’t a driver for my happiness. What I am really looking forward to is getting the GARDEN started for the new spring season. Hoping to get two plantings in maybe even a late bunch of greens and such.
Have a good day everyone. Enjoy the Lords day he made it especially for us.
Bill
February 28th, 2010 at 8:49 am
the warm layer will be an issue and dont forget about the warm ground temps. It would have to snow very hard for a few hours for the ground to cool off.
February 28th, 2010 at 8:49 am
where do you find the model runs 12z nam, gfs etc.? new to this, thanks!!
February 28th, 2010 at 8:49 am
Enough with the snow! Bring on sunny days and highs in the 70s and 80s.
February 28th, 2010 at 8:58 am
From the BHM NWS this morning:
ITS LOOKING
MORE AND MORE LIKE LIQUID PRECIP WILL DOMINATE MONDAY NIGHT AND
TUESDAY BUT THERE IS STILL AN OUTSIDE CHANCE THAT SOME SNOW COULD
STICK EARLY TUESDAY MORNING. HERE`S THE LATEST…
EVIDENT IN THE WATER VAPOR IMAGERY…OUR CULPRIT UPPER LEVEL
TROUGH HAS ALREADY TAKEN SHAPE OVER THE WESTERN HALF OF THE
UNITED STATES. THIS TROUGH WILL CONTINUE TO PUSH EASTWARD THROUGH
TODAY AND MONDAY…AND AS IT APPROACHES THE LOWER MISSISSIPPI
VALLEY IT WILL BEGIN TO SPIN UP ANOTHER GULF LOW TO OUR SOUTHWEST.
REMAINING POSITIVELY TILTED UNTIL OVERHEAD…THE UPPER LEVEL
TROUGH SHOULD GO NEUTRAL…AND EVENTUALLY NEGATIVE BY TUESDAY
NIGHT…BUT THE SURFACE LOW WILL BE WELL PAST US BY THEN. THIS
MEANS THE MORE INTENSE SFC CYCLOGENESIS WILL OCCUR TO OUR
EAST…MINIMIZING THE WINTER IMPACT HERE IN CENTRAL ALABAMA.
SO FOR US…NOT A GIGANTIC CHANGE TO THE FORECAST THINKING FROM
YESTERDAY. THE MAIN THING WE`RE SEEING IN THE MODELS FROM THE
OVERNIGHT RUNS IS THAT THE SURFACE LOW IS RUNNING A LITTLE
SLOWER…AND THE GOOD NEWS IS…SO IS THE WHOLE PATTERN WHICH
MEANS…SO IS THE COLD AIR ADVECTION. MODELS REMAIN FAIRLY
CONSISTENT WITH THE AMOUNT AND PLACEMENT OF THE QPF…WITH THE NAM
BEING THE WETTEST AND THE OBVIOUS OUTLIER. WILL CONTINUE TO RUN
WITH ALL RAIN PRIOR TO 2 AM OR SO…WITH A SWAP OVER TO SNOW NORTH
OF INTERSTATE 20. WITH CONSIDERABLY LESSER AMOUNTS OF QPF ACROSS
THE COLDER AREAS…COUPLED WITH THE WARMER GROUND TEMPERATURES…
NOT EXPECTING MUCH IN THE WAY OF ACCUMULATIONS. IN FACT…THROUGH
TUESDAY…THE AREAS THAT WILL LIKELY SEE THE MOST SNOW
ACCUMULATION…WHICH IS 1/2 INCH AT MOST…ARE PROBABLY GOING TO BE
OUR ELEVATED AREAS IN THE NORTH AND EAST. DYNAMICALLY…BECAUSE OF
THE FACT THAT THE MOST INTENSE CYCLOGENESIS DOES NOT HAPPEN UNTIL
AFTER THE LOW HAS PUSHED EAST OF US…THE COLDEST OF THE AIR REMAINS
JUST BEHIND THE BULK OF THE RAINFALL…AND THIS WILL LIKELY BE OUR
MAIN SNOWFALL PROHIBITER.
February 28th, 2010 at 8:59 am
Last night was the most beautiful night!
The moonlight was so bright – it made me wish
I were at Cheaha for a moonlight hike.
February 28th, 2010 at 9:27 am
ruth, where do you find your information? models, etc.
THANKS!
February 28th, 2010 at 9:29 am
been sayin it since friday. too warm. james and team know this. thats why they have forecasted rain/snow to not get hopes up. good call. only ignorance would dismiss the warm layer.
February 28th, 2010 at 9:30 am
I, like a number of bloggers over the last few days have been concerned about the warm layer. There is no real cold air to our north. Checked a number of cites to our north all having highs at least 32degrees or above. So the system will have to make it’s own cold air for snow here, thus the “warm layer”.
Short notes on the subject from Mr Spann and Mr Peters:
JS- But, of course, for the accumulation forecast, you have to consider the soil and surface temperatures.
BP-While the upper air temperature profile continues to support the idea of snow, there continues to be a substantial layer of warm air right next to the ground. While this warm layer is only a couple of thousand feet thick, it is certainly enough to melt a good deal of snow falling into it.
Looks like R A I N. Will see.
February 28th, 2010 at 9:36 am
Figures…….All winter long we have had this miserable artic air, now when we actually need some it doesnt show up.
February 28th, 2010 at 9:58 am
Just not the year for a big snow at one time in central Alabama. Maybe next year. Bring on the storms.
February 28th, 2010 at 11:08 am
Here are the links to the models:
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/
The models update from left to right (see the dates on the rows beside each model) The NAM updates before the GFS. When you want to look at the maps, click on “Fine” on the latest date for whichever model you are looking at (GFS or NAM) On the next page, you will see a series of colums and numbers. The column you want to look at is the 850mb Temp, MSLP, 6hr Pcpn. Then you look for the hour in that column. I’m not good at figuring out which hour pertains to what time, so I just figure about how many hours away the event is and start clicking those hours until I find an image that shows the correct day at the bottom of it. Once you figure out the hour, you can then open the link above in a different tab and go to the other model at that hour to compare models. Just make sure the image dates and times match on each so you can accurately compare them.
As for reading the maps, generally we use the “blue line” (also known as the the “540 line”) as a good indicator of a rain/snow line. Any precip north of that line is considered snow, south would be rain.
In determining the approximate snowfall amount, look to the legend on the left of each image and determine how many inches of precipitation matches the shade of precipitation on the map in your area. The liquid equivilent of rain to snow is 10:1. So 0.25 inches of rain would translate to 2.5 inches of snow. This is just a general rule, not set in stone. Colder air can increase the ratio to 15:1 and so on.
There are many other factors that affect the amount of accumulation and the actual snow itself occurring. I suggest anyone new to this, go watch several videos on the blog for the past week. James and crew provide alot of info in those.
During the time leading up to the event itself, you may consider logging into the live chat on this site and just read the info provided by others.
To see what your local NWS office is saying, go back to the link above and punch in your zip in the upper left side of the screen. Then scroll down to the bottom right and click on “forecast discussion”.
Hope this information is helpful.
February 28th, 2010 at 11:09 am
Don’t give up yet!!!
February 28th, 2010 at 11:48 am
Here’s a link to what the gfs thinks will happen. Not sure it’s accounting for the warm ground temps.
http://wxcaster.com/gis-gfs-snow-overlays.php3?STATIONID=BMX