Tracking Colder Air Soon

Thursday, October 30th 2014, 4:31 am

By: Alan Crone

A strong Canadian clipper will move across the central and Midwestern U.S today and will shove a cold front into the state later this afternoon. The air mass behind this boundary will be cold. Frost and freeze warnings will be required for portions of the state Saturday morning due to this strong front. A second storm system will arrive from the southwest Monday and Tuesday with high rain chances.   Temperatures this afternoon will move into the mid or upper 70s before the cold front arrives late this afternoon.

Our readings this morning are not quite as cold as yesterday, but still would require the kids to take the jackets to the bus stop this morning. The afternoon highs will move into the 70s with southwest winds and mostly sunny conditions before the cold front arrives with falling temps and gusty north winds.

The upper air pattern is from the northwest to the southeast.   A strong upper level system is moving across the central U.S. this morning atop a mid-level ridge of high pressure centered across the southwestern United States. As this clipper moves southeast, a surface boundary will move across the state as the day progresses and should enter the northeastern third of the state between 3pm and 6pm. As the front passes strong gusty north winds will commence in the range of 15 to 25 mph helping to move colder and drier air into the state. A few clouds will be likely with the passage but we continue to think most of the area is too dry to support precip to the surface. I suppose a few sprinkles or small showers may be possible across far eastern or southeastern OK with the passage. Some locations across southwestern Missouri into northwestern Arkansas could support a small shower or two.

The model data continues to support cold air backdoor across the region by Friday morning. This would allow Friday morning lows in the lower 40s with afternoon highs only in the lower to mid-50s with mostly sunny conditions and gusty north winds.   Friday Night football and Halloween festivities will see temps in the upper 40s by 7pm and into the lower 40s by 9pm.

Saturday morning we're anticipating freezing temperatures across a large portion of northeastern OK. Our friends at the NWS have issued freeze watches that will more than likely be upgraded to freeze warnings later tonight for the Saturday morning period.   NAM Raw profile temps are colder than our forecast lows, and would offer morning lows in the mid-20s resulting in a hard freeze.   There remains a question as to the exact cloud cover conditions and wind speeds for the early morning hours.   The presence of a few clouds with north breezes around 10 mph may keep the temps around 30 or so. At this point, we're going with lows around 28-29 but it could be a few degrees lower.

Saturday afternoon temps will hang in the lower to mid-50s with east to southeast surface winds around 10 to 15 mph as the upper air pattern transitions to a southwesterly flow.

A major trough currently developing off the west coast will move inland this weekend with a storm system developing at the base of the trough. This system will move across the state Monday into Tuesday with a surface cold front slowly moving southeast. This system will bring the chance for rain and thunderstorms into the state.

Sunday the southeast winds will return with highs moving into the mid or upper 60s.   Monday and Tuesday another storm system will be nearing the state with increasing rain and thunderstorm chances. Available data support moderate to heavy rainfall with 1 to 2 inches a possibility.   We'll unpack more regarding the Monday and Tuesday system tomorrow.

Thanks for reading the Thursday Morning weather discussion and blog.

Alan Crone

KOTV