Active Pattern Soon

Wednesday, September 17th 2014, 4:39 am

By: Alan Crone

Some patchy fog will be likely in some locations across eastern OK this morning along with heavy dew. The fog may be locally dense in a few locations. We're tracking a chance for a few thunderstorms this morning across the Missouri Valley into part of northeastern OK for the next few hours.   These should remain well northeast of most of NE OK including the Tulsa metro. Another slight chance of showers remains later this afternoon across the far eastern third of the state. The next wave quickly follows late tonight into Thursday morning with additional thunderstorm chances from southeastern Kansas, southwestern Missouri, northeastern OK, and northwestern Arkansas. A few of the storms could be strong to severe but the overall chance of storm activity will remain in the 30% to 40% range for the Tulsa metro. Temperatures both today and tomorrow will be above the seasonal average with highs this afternoon nearing 90 to 92 along with south to southwest winds.   The weekend forecast remains complicated regarding timing and location issues but the chance of a wet Saturday afternoon or evening remains in the forecast.

The overall pattern remains consistent with a mid-level ridge of high pressure over the Rockies, a trough across the northeast, and a series of upper level disturbances moving in the northwest flow aloft near the area. The front that moved southward across the state Monday is now lifting northeastward as a warm front this morning and will be located near southeastern Kansas. The upper air flow from the northwest will bring the first wave near the area this morning with a small cluster of thunderstorms likely to develop northeast of the state. But the trajectory of this expected system will be very close and we'll need to keep a small chance of thunderstorms in the forecast this morning northeast of Tulsa.

Later this afternoon with daytime heating a few additional storms may develop on the eastern edge of the state with a few being strong to severe. This will keep a chance of storms in the forecast along the OK-Arkansas state line later this afternoon. Lastly a final wave will approach in the northwest flow pre-dawn Thursday with another small complex of storms possible. This system may be closer to the Tulsa metro and therefore will require a slightly higher coverage of showers or storms Thursday morning.   The threat for strong to severe thunderstorms early Thursday is not zero but does remain low. The models have been all over the map with the precip forecast Thursday. The operational models have a higher likelihood for precip than we are currently depicting in our forecast. Some of the hi-res experimental products offer some lower coverage. I suppose we'll continue with a 30 to 40% chance.

I think we'll get a break Friday, including Friday night football, with dry and pleasant conditions with temperatures slightly above the seasonal average. The toughest part of this forecast centers on this weekend and early next week as the possible remnant moisture of tropical system Odile may become enveloped near the state. The model data has not been consistent with the placement of some important features and has gone from a fairly progressive system to a rather slow system.   The last few runs have indicated part of the circulation-wave may traverse the state with a very weak upper air flow resulting in a prolonged period of rain and thunderstorm activity. Again, this is in contrast to previous runs that took the wave north of the state but brought some moisture southward along a cold front that entered the state Saturday and exited the area Sunday morning.   The last EURO run is much slower compared to previous runs. This would keep most of the precip west of the eastern third of the state through most of Saturday before bringing the rain into the area Saturday night and continuing for most of Sunday. The GFS is about a day faster and would thin out the pops Sunday morning. Needless to say, we continue to have low confidence on the specifics of the weekend forecast other than to indicate the probability for precipitation will be high. We'll make adjustments to the weekend numbers but the overall trend of rain and storm chances will remain high