The Forecast Funnel

The first image visible below is a hemispheric 500mb map from Unisys, dated 1200Z on Jan. 27, 2009.
500 mb hemispheric map

We can see on this map that, at least for the southern U.S., things are about to get warmer. The low pressure that is in northern Mexico/western Texas should move NE into the Ozarks and the Ohio Valley, whereas the "Rocky Mountain High" will likely move up into the northern Plains and into Ontario.

For the next images, we move down the forecast funnel to the synoptic scale. Taking a look on somewhat of a broad synoptic scale, the following image shows vorticity and height at 500 mb.
500 mb map of vorticity and height

This map shows a fairly tight height gradient for the pressure. The low height (corresponding to low pressure at the surface) can be seen near the Four Corners. Doing the "berries and cherries" method of advection analysis shows that the air from central Mexico to the Gulf of California (warmer air) will move into the Oklahoma area.
The next image is of the GOES-13 satellite imagery at 10.5 μm wavelength.
GOES-13 image

Note the presence of the large cloud mass over Oklahoma, stretching back into west Texas -- the same path that the advecting air will be taking. This could get interesting, as we've been icing for a few hours, and it looks like the precip has at least a chance to continue. Let's go ahead and call this the problem of the day. Since we're not sure what will happen, we'll have to take a look at the mesoscale systems to make a better prediction.

Speaking of mesoscale systems, let's take a look at radar. The following image is from the RIDGE National NEXRAD Radar mosaic and is dated at 12:08 UTC on Jan. 27.
NEXRAD radar image

Some of the clouds that we saw on the satellite are actually dropping precip. Just from the radar, though, it's nigh on to impossible to determine what type of precip this is. A sounding would be helpful here...
OUN sounding 2009012700Z

Well, wasn't that handy? Note that the sounding is from 00Z -- the 12Z sounding was incomplete. With the temperatures the way they are, though, that's going to be some combination of freezing rain and sleet. It should only last for today (Tuesday) from the looks of the radar progression.

Forecast:

Now-6 hours: Precip continuing (currently freezing rain), changing to freezing rain/sleet (based on radar/sounding.)
6-12 hours: Precip tapering off (based on radar), skies clearing (based on satellite.)
12-48 hours: Temperatures warming (based on 500 mb map), but inhibited by some radiation going to melt sleet/ice cover. Pressure rising (based on hemispheric map.)