Tracking Rain Chances

Wednesday, November 19th 2014, 4:36 am

By: Alan Crone

We experienced some record lows yesterday morning across the northern third of the state, but temperatures this morning are several degrees warmer due to southwest surface winds across the area during the last 24 hours. A weak front will move across the area today bringing a wind shift and highs in the upper 40s and lower 50s, but no precipitation will occur. We are tracking two more waves that will bring some rain chances back to the eastern third of the state soon. The temperature trend will continue to support warmer air moving into the weekend, but another cold front enters the region Monday bringing colder air back to northeastern OK for a few days.

The main upper level trough that has been parked over the Great Lakes region for the past week is finally sliding eastward as the upper air pattern undergoes a change. This will allow a moderating air mass to impact the area for the next few days, even though we will see some variation in daytime highs, the arctic air mass “has left the building". A surface boundary will move across the state this morning to midday with a wind shift from the northwest and a few clouds, but very little impact will occur on sensible weather conditions.

The disturbance of note for the weekend is moving out of the Aleutian Island chain early this morning and will dive down the Pacific along the west coast before turning inland Thursday. This disturbance eventually ejects across Texas Friday night into Saturday with increasing rain and thunderstorm chances for the eastern half of Oklahoma. Before this main wave arrives, a small disturbance should bring a few showers or some drizzle into the eastern third of the state late Thursday night into Friday morning, with the Tulsa metro located on the western edge of this precip possibility. This will result in a 30% chance of showers or drizzle for the region Friday morning to midday. Rain with some embedded thunder will be likely Saturday as the stronger short wave moves across Texas where some severe weather may be possible southeast of the DFW metro. No severe weather will occur in eastern OK with the weekend system, but pockets of moderate to heavy rainfall will be possible. The Saturday system could be impacting northeastern OK by morning and moving eastward by early to late afternoon before exiting eastern OK late Saturday night into pre-dawn Sunday morning. Temperatures during the event will be too warm for any wintry weather threats. Bufkit profiles indicate daytime highs Saturday could reach the lower upper 50s.

The next cold front enters the state either late Sunday night or Monday morning and will bring another shot of cold air for Monday and Tuesday of next week. The EURO data seems to be the deepest and colder of the model suggestions, and we have blended our numbers in this direction taking into the account the colder air mass modeled at the 5k foot level.

A quick word about Thanksgiving and the day after. The models greatly diverge by the early portion of next week. The GFS would keep us relatively mild and dry, while the EURO would bring another significant system into the area by Friday morning to midday. The “usual" nod would be in the direction of the EURO, but the last few ensemble runs have slightly more support for the milder GFS solutions. Bottom line: the confidence on anything past next Tuesday is very low.

Thanks for reading the Wednesday morning weather discussion and blog.

Alan Crone

KOTV