Weather Discussion > Winter Weather

Possible Winter Storm in the south Sunday and Monday

(1/13) > >>

Lightning:
I am sure you all have heard about the possiblity of ice, snow and sleet across the deep south for Sunday and Monday. Why are these kind of weather events so tricky, complicated and difficult to forecast?

TWCToday:

--- Quote from: TWCC_Lightning on January 07, 2011, 02:18:07 PM ---I am sure you all have heard about the possiblity of ice, snow and sleet across the deep south for Sunday and Monday. Why are these kind of weather events so tricky, complicated and difficult to forecast?

--- End quote ---
A large part of forecasting is based on computer models and analyses. There are several highly regarded models: GFS (American) ECMWF (European) and NAM. There are countless others that are considered less accurate but are used to compare to the main models. Most models are run four times a day. 0z, 6z, 12z, 18z. 0z and 12z models are typically more accurate because they contain the latest observations and balloon launch data from across the country. This year has been VERY tough for forecasters because there have been such HUGE changes in each model run with each model showing a different picture. The Euro might show 20in of snow at 0z then only 1in by 12z. There has been little model consistency this winter. To throw another headache in the system.... Forecasting events in the south is always extra tricky when you have to consider temperatures.

phw115wvwx:
Here's the reason why forecasting winter storms is so difficult:  A difference of 50 miles in a storm's track can mean the difference between a foot of snow, a quarter inch of ice, or an inch of rain for your area.  Why?  It's because precipitation type is extremely sensitive to the temperature at the surface and aloft.  During one storm last month, I observed the snow suddenly changing over to all sleet, and the forecasters asked me to do a special balloon launch in the storm.  Just above the surface, my balloon revealed a layer no bigger than a thousand feet in depth where the temperature was above freezing.  The highest temperature I recorded in that little layer was just 33.5°F.  One degree can literally mean everything, which is why the storm track is so critical.

Now, try your luck forecasting a storm several days out in the future given how sensitive precipitation type is to the temperature and with how inconsistent the models can be.  The slightest details in the first 24 hours of a model solution can severely affect what the models show by days 3-7, so even the intensity and amount of moisture available for the storm can be highly uncertain.  Some of our models can barely even resolve that 50-mile difference that I mentioned previously.  The bottom line is that it's just not easy.

toxictwister00:
It's amazing to see the swath of WSW (Winter Storm Watches) that extend from ARK to N/SC. NAM really wants to dump on I-20 a large area of 8-10 inches of snow from Brimingham to Atlanta to Athens and north. But that's only if the latest NAM run has it's way. Speaking of the NAM 00z run is running right now, I'm interested to see what it says. I plan on making a snow map tomorrow night (preliminary) and again Sunday (Final) on this storm, I'm gonna post it here and at other weather forum communities I'm apart of. One of our local mets said this evening to stock up for 2 or more days in case to prepare for the worst.

WeatherWitness:
I'm going to be interested in seeing if we get anything from this storm. We're going to be on the very tail end of this, so I'm not sure, especially since TWC hasn't said anything about an impact on Texas. However, both TWC and the NWC and predicting a great chance (70-90 percent) of a wintry mix on Sunday and possible flurries later. Obviously, nothing big, but ANY type of wintry precipitation in Dallas is something to note. :yes:

It's going to be quite chilly though...we may be below freezing for a couple of days. :brr:

Navigation

[0] Message Index

[#] Next page