Friday, January 16, 2015

A reprieve from the January cold!

We've had our share of cold weather to start 2015 with an average temperature for the first half of the month that is over 6 degrees below normal! That will make the next 5 days or so even more enjoyable as warmer air overtakes the region producing multiple days with highs in the 50s and lows above freezing.

Even though this past week was climatologically the coldest week of the year, the Mid-South has been in "outperform" mode. Through January 15, the average high temp has been just under 43 degrees, which is 7 degrees below normal. The average low of 27.2 is nearly 5.5 degrees below normal.
Temperature so far this month (blue bars) have generally been well below normal (brown bands). We'll have more blue bars in the red area (above normal) by this time next week!
It's also been fairly dry to start the year with precipitation about an inch below normal already. The dry spell continues, but now with more pleasant temperatures that should result in more folks outside this weekend, soaking in some welcome sunshine and shedding the winter coats! Even a weak cool front Saturday night will do little to suppress temps as highs both Saturday and Sunday reach the upper 50s. No rain is expected with this front as dry air throughout the atmosphere will mean just a few clouds Saturday night and a brief wind shift.

Output from the "new" GFS model (see below) for Saturday night as a weak cold front moves through. The closest precip looks to stay along and north of the Ohio River as dry air won't support rain this far south.
Monday will see highs approach 60 and Tuesday would be the same except for a few more clouds with another cold front that is also expected to pass throughout precipitation. We're forecasting another day of highs in the upper 50s. (Our normal high this time of year is near 50.)

The tide appears to turn as we head into the end of next week as cooler air seeps in behind Tuesday's front with a general downward trend in temperatures. In addition, a "southern stream" weather system, which rides the subtropical jet stream positioned in the northern Gulf of Mexico, will throw abundant cloud cover over the area late next week. Being a week out, precipitation forecasts could change significantly, but for now most of the precip looks to stay just to our south. However, with colder air back in place, we'll have to monitor this system closely for the potential of a wintry mix. Too soon to make any calls on that though!

Output from the "new" GFS model (see below) for next Thursday night as low pressure moves through the northern Gulf in the "southern stream." Temps will be cold; the question is where the northern edge of the precipitation will be. Graphic courtesy WeatherBell Analytics.
For now, enjoy the beautiful January weekend that continues into early next week! These are what we call "bonus days" in a typically cold, often cloudy, time of year.

Side note - for weather geeks

For you weather weenies out there, we have referenced and posted graphics on this blog in the past few months from a "parallel" or "upgraded" GFS computer model that was being tested alongside the operational GFS. The GFS is the American workhorse model - with global output and long-range capabilities. As of Wednesday morning, January 14, that "upgrade" became the "new" operational GFS. There are several improvements within the model, but perhaps the biggest is an increase in horizontal resolution by nearly four-fold in the ten day forecast and more than three-fold out to 16 days.

An increase in horizontal and vertical resolution was also accomplished on the ensemble modelling system that the GFS is a part of (the GEFS). This increase in resolution was enabled by a recent tripling in capacity of the supercomputers NOAA runs the models on, mostly funded by the Hurricane Sandy supplement that directed tens of millions of federal dollars into a lagging NWS computing infrastructure.

NOAA supercomputers "Tide" and "Gyer" process NWS model data used globally for atmospheric prediction.
Other valuable improvements in various computer models are forthcoming this year, but this month's upgrade was certainly welcome and follows other recent upgrades, including the operational launch of the HRRR high-resolution rapid refresh model nowcasters rely heavily on and the upgrade of the high-resolution hurricane model, known as HWRF. All of the model upgrades, collectively, will only help to improve the accuracy of forecasts provided by your local weather folks. As you know - garbage in, garbage out.

Erik Proseus
MWN Meteorologist

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