Warmer, Then Much Colder and Wet
Could get interesting, real interesting around here starting on Friday and continuing into the day Sunday. Before getting into that, thought a brief look back at this recent cold snap would be instructive. Notice the hours below freezing over the past week as recorded by the OK Mesonet. Notice also, a number of locations made it below the zero mark which is the coldest around here since Feb of 2011. By the way, Tulsa proper had 67 continuous hours of below freezing temperatures from late Wednesday till Saturday afternoon when we finally started to thaw.
This extended period of very cold weather has also had an impact on soil temperatures as you can see on the soil temperature map at 2” below ground level, also courtesy of the OK Mesonet.
Despite strong southerly winds, temperatures today were held in check by considerable high level cloud cover, but that same combination of clouds and strong southerly winds will keep temperatures from dropping much if at all overnight. The max/min for today has so far been 54/29 as compared to the normal values of 47/27. As we go through the night tonight, temperatures may drop off a few degrees but should in general be near the 50 degree mark to start the day on Tuesday.
Strong S/SW winds to start the day will be relaxing by the noon hour as a weak front/wind shift moves through the area briefly shifting our winds to northerly and the wind speeds diminishing to around 10 mph. Even so, the strong southerly winds in the morning will create a high fire danger. Considerable high level cloudiness during the day should hold our daytime highs into the upper 60s which is quite a change compared to just a few days ago.
Wednesday will see a return to strong southerly winds and therefore a high fire danger. Morning lows will start off near our normal daytime highs, i.e. mid-upper 40s, and daytime highs will be in the upper 60s and even some low 70s. Right now it looks like we should have considerable high level cirrus cloud cover to keep our daytime temperatures at least somewhat in check.
Then there is Thursday. A strong cold front will be arriving that morning with gusty northerly winds for the rest of the day bringing a return to much colder conditions. This will not be a repeat of what we had last week as the cold air will be very shallow and the coldest conditions will stay well north of us instead of dropping down on top of the state. Even so, look for an inverted temperature profile with morning temperatures in the 40s and perhaps even some 50s for the more southern counties. The colder air will be surging southward during the day with temperatures holding steady at best or more likely dropping into the 30s late in the day. Only a few showers are expected during the day, but that will be changing overnight and for Friday.
Friday, Saturday and perhaps Sunday is when it gets interesting as you can see on our forecast page. The cold air this time around will be very shallow and will likely have considerable difficulty making it past the higher elevations of E/SE OK, if it does at all. The air aloft over this shallow cold dome will be well above the freezing mark and there will also be considerable moisture available. Thus, cloudy skies and widespread precipitation will start on Friday and continue through Saturday and not likely to be ending till late Sunday. Given the extensive warm layer aloft, conditions at the surface will dictate what type of precipitation takes place. This far in advance of the event makes that a very difficult call but the general consensus at this point suggests a county or so either side of the I-44 corridor may well be the dividing line with freezing temperatures to the NW and above freezing to the SE. Given the uncertainty, here is the best call at this point regarding locations most likely to be impacted by ice.
Another factor will be the abundant moisture available for this system to work with. Drought has once again become widespread across the state but as you can see, this system has to potential to drop some very significant rainfall. In fact, some locations may go from drought to flood as flooding may turn out to be a serious concern, particularly on Sunday.
This should be all coming to an end by Sunday night and looking further down the road, the 8-14 day outlook maintains an above normal temperature pattern should be the general rule going into that following week, on average. That time frame may also see an additional chance of at least scattered showers.
So, stay tuned and check back for updates.