Outlook (Thursday-Sunday)

While medium-range models have similar ideas in general trends, there are enough differences in smaller day to day details to keep the confidence in any solution fairly low.  Luckily, we shouldn’t be dealing with any significant weather makers through the upcoming weekend.

A large re-establishing trough will be located over the Eastern U.S. with a building ridge over the west through Saturday.  In between, strong north northwest flow aloft will be found across the Plains.  Embedded in this flow will be several strong short wave troughs which will be capable of producing brief periods of virga/sprinkles/flurries during the days of Friday and Saturday, but the atmosphere should be too dry to allow organized precipitation.

What these waves will do is bring reinforcing shots of cold air into the Southern Plains with the greatest impact felt in Eastern Oklahoma.

By Sunday, the upper ridge will begin to flatten and move over the Plains as a strong upper system moves into the Northwestern U.S.  This will result in lowering surface pressures across the High Plains and strong south winds developing across the state.  The strongest winds will be in the Panhandle and Northwest Oklahoma.

During the Sunday/early Monday time frame, we should see mild temperatures across the state with a weak cold front slowing the warming by Monday afternoon.

Thursday morning: 29

Thursday: 47

Friday morning: 26

Friday: 46

Saturday morning: 25

Saturday: 49

Sunday morning: 26

Sunday: 55

Some very light snow possible tonight…

Snow is developing over the northwest part of the Texas Panhandle and the western end of the Oklahoma Panhandle this evening.  This is in a region of fairly strong lifting associated with a short wave trough moving eastward through Northern New Mexico.  This feature will move east southeastward during the overnight hours, tracking across Oklahoma in the process.  Despite a very dry atmosphere, it appears likely that a couple of bands of very light snow will be able to persist with this feature.  Most locations will see only flurries, but there may be enough to dust the ground from western toward south central parts of the state.  Precipitation is expected to reach Western Oklahoma between 9 pm and Midnight, and exit Southeast Oklahoma during the morning hours tomorrow.

Snow spreading into Central Oklahoma – Blizzard on-going west…

Making my final guess on snowfall amounts.  Latest satellite, radar trends / morning model guidance suggests that snowfall will be heaviest near and northwest of I-44 east of Oklahoma City, and north of an east/west line from just south of I-40 west of Oklahoma City.  Excessive amounts and blizzard conditions will occur over Northwest Oklahoma.  Totals are likely to approach 2 feet in isolated areas with 4 to 5 foot drifts.  Already this morning, Alva has seen 9 inches of snow and Laverne has seen 8 inches.

Snow started mixing with rain in Okarche at 9:20 am.  A transition to all snow is likely within the next 1 to 2 hours.  In Okarche, 6 inches of snow is likely – 8 inches of snow is possible – and 10 inches of snow would not be out of the question.  It should be noted that all of these numbers are below model guidance which ranges from 10 to 14 inches for Okarche.

In Oklahoma City, snow will likely reach 2 to 4 inches over southeast portions of the metro area, and upwards of 6 inches over the northwest.

Increasing north winds will cause a considerable amount of blowing and drifting snow, while reducing visibilities to ¼ mile or less.  Blizzard or near blizzard conditions are likely for any area that sees significant snowfall.

First snow begins with major winter storm…

A strong winter storm will be bringing very heavy snowfall and blizzard conditions to parts of Oklahoma during the next 36 hours.

Evening model guidance is basically on the same track as the previous 24 hours with only a very slight shift south with the upper system moving out of New Mexico.  This storm will track eastward through the Red River Valley, reaching Arkansas by Tuesday morning.

For the most part, forecast snow totals have not changed a lot.  It appears that there will be a fairly wide swath of snow ranging from 1 to 5 inches from Southwest Oklahoma into Northeast Oklahoma.  From there, a rapid increase in snowfall is expected into Northwest Oklahoma – where snow is beginning a few hours earlier than previously expected.  Confidence is increasing in extreme snow amounts / approaching 20 inches / over far northwest parts of the state.

The strongest winds are expected to be in Western Oklahoma, and as a result, those areas will experience blizzard conditions with less snow.

Outlook (Monday-Wednesday)

First and second periods of this forecast have been discussed ad nauseam with focus on the significant winter storm which will affect the state through Tuesday morning.  Both ECMWF and GFS are in good agreement with the track of the system across the Red River Valley and then to the Arkansas/Missouri border by Tuesday morning.  The large upper low will then settle into the Ohio Valley on Wednesday.

Showers and thunderstorms are likely to be ongoing at daybreak Monday.  By Noon, the surface low will be moving southeast of Okarche and winds will begin to back to the northeast and then north as the day progresses.  Heavy rain will transition to heavy snow during the early afternoon, and at least some snow will fall until almost sunrise on Tuesday.  After a low of 38 degrees Monday morning, the temperature is likely to stay steady and then fall to 30 degrees by late afternoon.

Winds will still be brisk out of the northwest on Tuesday morning and the low will drop to 26 degrees.  Skies will begin to clear during the morning hours of Tuesday with a sunny afternoon expected.  With snow cover, the high will struggle to reach 34 degrees.

Wednesday morning will see the coldest temperatures of this period with the low dropping to 20 degrees.  Skies will be sunny on Wednesday, but with extensive snow cover still around, the high will only be around 37 degrees.

Monday morning: 38 / Showers, thunderstorms

Monday: 38 / Snow

Tuesday morning: 26 / Light snow

Tuesday: 34

Wednesday morning: 20

Wednesday: 37

Blizzard Warning in effect for portions of Western Oklahoma…

*** Blizzard ***

There is very little change in the thinking of last night as morning guidance continues to zero in on a track for our upcoming storm.  In fact, I used the same map as last night for forecast snow totals – only adding the region where I expect the combination of wind and snow will produce the worst conditions / blizzard /.

By this evening, I hope to squeeze the snowfall total gradient a little tighter.  There may be some areas along a line from Nowata to El Reno to Cordell to Erick where there will be ranges of 2 to 8 inches of snow over a fairly small zone.  I will update again by 10:30 pm.

*** Thunderstorms ***

One thing not addressed so far has been thunderstorm potential.  Storms are expected to form this evening just prior to Midnight across Northwest Texas as strong lifting begins to overspread the warm sector.  A few of these storms may be severe given marginally sufficient instability and strong wind shear profiles.  Some large hail and damaging wind threat will exist as the storms track eastward across the southern third of the state during the overnight hours.  The severe threat would be ending by Noon as storms exit Southeast Oklahoma.

Major winter storm still on track to impact Oklahoma…

00Z model data shows the forecast track of the strong upper system approaching the Southern Plains to be on generally the same course.  Timing is similar to previous runs with only a slight shift southward in the track.  This southward track opens up just a little bit more of Oklahoma to the potential of heavy snow.  New model data also shows rapid intensification of the surface cyclone as it tracks from near the Red River toward Fort Smith, Arkansas by Monday evening.  As with the upper system, the surface reflection is just a little farther south.

The transition of rain to snow will move into extreme Northwest Oklahoma around Midnight on Monday – the central parts of the state by Noon on Monday – and finally into Northeast Oklahoma by 6 pm.

The main changes to this forecast include: a) Increasing snowfall totals in northwest and north central parts of the state, b) Tightening the gradient from low to high snowfall amounts, and c) Removing or lowering accumulations on the south and eastern sides of the forecast snowfall.  Max snowfall amounts are going to be very significant.  15+ inches of snow cannot be ruled out.  Meanwhile, the rapid intensification of the surface cyclone is going to be drawing warm air into the north central and northeast quadrants of the storm.  This may severely limit snowfall production for a time in parts of Northeast Oklahoma.

As previously noted, wind is going to be a big problem with this storm.  Sustained north winds of 30 mph with gusts to 50 mph are going to be causing near-blizzard conditions in almost any area that receives accumulating snow.  For areas around Okarche, no travel should be planned from mid-afternoon on Monday through at least mid-afternoon on Tuesday.

As is typically the case, even slight changes in the track of the system can have large impacts on snowfall amounts for any given location.  My next update will be by Noon on Sunday.

Major winter storm to impact state…

In a significant change to the thinking of a few days ago, a major winter storm is now expected to bring heavy snow to a large part of western and northern Oklahoma with blizzard conditions in the northwest part of the state.

The next major storm to affect the state is now forecast to be much stronger, farther south and wetter than previously thought.  The system is currently moving southeast over the West Coast and will be diving to the Four Corners by Sunday morning.  It is expected to close off and track east near the Red River on Monday.  In response, deep surface low pressure will organize over Northwest Texas and track toward eastern Oklahoma.

Snow is expected to start over western Oklahoma around 9 pm on Sunday and won’t be exiting the northeast part of the state until after sunrise on Tuesday.  The heaviest snow / where a foot is possible / will likely be limited to Northwest Oklahoma.  However, significant accumulations can generally be expected anywhere northwest of I-44.

Of greater importance with this storm over the last couple of storms is the amount of wind that is expected.  In the area where I have outlined with blizzard conditions, sustained north winds of 35 mph with frequent gusts over 50 mph are likely.  The strongest winds will start around daybreak on Monday and not start to subside until daybreak on Tuesday.  These winds will cause a considerable amount of blowing and drifting snow making travel nearly impossible in some areas.

It is worth noting that the 12Z NAM (23rd) has just come in with a much weaker cyclone and a resulting lower snowfall / wind forecast.  Currently, this run is an outlier.  However, it is important in that this is the first model output which takes in data that has sampled the system as it is passing over land.  Should other models follow this trend, a strong downplay to the current forecast would be needed.  More should be known by later today.

Outlook (Thursday-Sunday)

The parade of storms continues.  The strong storm system moving out of the Southern Rockies into the Central and Southern Plains this evening will make its way to the Upper Midwest by Friday morning.  Another strong storm system will be moving over Oregon/Northern California by Saturday morning – ending up near the Four Corners by Sunday morning.  The models seem to be in reasonably good agreement about the above solutions with the exception of the GFS seeming to be a little too fast with the next system in the late Saturday/Sunday time frame.  I will accept a bit slower solution closer to the ECMWF.

This evening, waves of precipitation will continue to spread northeastward across the state as lifting increases with the approach of the Southern Rockies system.  Forecast temperature profiles suggest that most of Oklahoma southeast of I-44 will be seeing a cold rain, with areas northwest of I-44 having a mix of rain, freezing rain, sleet and snow.  Areas northwest of a line from Sayre to Watonga to Bartlesville are likely to see the most snow, with accumulations of 3 to 6 inches possible by Thursday morning.  In addition, we will be increasing the chance of thunderstorms starting at Midnight in Southwest Oklahoma, with the activity spreading eastward across the southern 2/3′s of the state through Thursday morning.  Given impressive shear profiles and sufficient elevated instability, some of the storms may become severe over the southern third of the state with large hail the primary threat.  In Okarche, it will be breezy tonight with a brisk southeast wind.  Snow and sleet accumulation should be between one and three inches.  The low temperature Thursday morning will be around 30 degrees.

The heaviest precipitation will have pushed east of I-35 between 9 am and Noon on Thursday.  However, snow will still be falling in northwest and north central parts of the state.  As surface low pressure passes over Okarche, winds will gradually veer to a westerly direction by 6 pm.  There will be a chance of light snow through the evening hours, but significant accumulating snow should stay north of Okarche.  The high will make it to the mid 40′s before the cold front passes around sunset.

Clearing skies, and north winds blowing off an expansive snow field will allow the temperature Friday morning to fall to around 19 degrees.

The high temperature on Friday will be near 37 degrees.  A weak short wave trough embedded in the flow between the two stronger systems will be approaching the state late Friday and early Saturday.  This will increase cloud cover, but no significant precipitation is expected.

The low Saturday morning will once again drop into the 20′s.  For Okarche, the low should be around 25 degrees.   The high on Saturday will be near 47 degrees with winds becoming light out of the south.

The low Sunday morning will be near 34 degrees.  A cold front will be pushing into the northwest corner of Oklahoma by early afternoon.  It currently appears that this front will be mostly dry as it moves through the state.  Winds will be quite gusty ahead of the front out of the southwest and become strong out of the northwest behind the front.  The high Sunday will be near 57 degrees.

Thursday morning: 30 / Rain, freezing rain, sleet, snow, thunderstorms

Thursday: 44 / Showers, snow showers

Friday morning: 19

Friday: 37

Saturday morning: 25

Saturday: 47

Sunday morning: 34

Sunday: 57

Winter weather looking more likely for parts of the state…

A very complex winter weather event will unfold over Oklahoma over the next 48 hours.  This evening, a strong storm system is diving southeastward through California.  In advance of this system, a weaker short wave trough is moving northeast from near El Paso, Texas.  Lifting associated with the lead wave is generating widespread precipitation from Southeast New Mexico to North Texas.  This precipitation will rapidly advance northeastward across Oklahoma tonight and early Wednesday.

Forecast soundings suggest that the air not too far above the surface will be cold enough for snow to mix with rain across almost all areas of the state.  For areas generally south of I-40, snowfall should not be heavy enough to allow accumulation.  Any area north of I-40 may see snow fall heavy enough for at least 1 to 3 inches of accumulation.  This will be similar to the last snow event where accumulation occurred despite surface temperatures above freezing because of the snowfall rate.  The most significant accumulation will be in Northwest Oklahoma where 2 to 6 inches of snow is possible.

Precipitation is likely to lessen in areal coverage and intensity for a period of time late Wednesday afternoon and evening when the state is located between systems.  Forecast soundings suggest that warm air above the surface will have moved in on south winds allowing most of Oklahoma to see a light cold rain.  By very early on Thursday, there will be a rapid increase in precipitation over western and southern parts of the state as the main upper storm nears.  This activity will include showers and thunderstorms over most of Oklahoma with snow in the northwest.  While the storms will be moving out of Eastern Oklahoma by early afternoon, snow is likely to continue under and north of the strong upper system near and just south of the Kansas border.  It is in these areas where some of the highest snowfall totals will be found / near 8 inches.

The general trend of various models has been to shift the track of the main storm system just a little south with each run.  If this trend continues over the next 24 hours, the forecast area of heavy snow may need to be shifted farther to the south.