Cold Tonight, Warmer Fri/Sat.

What a difference a day can make!  Notice the 24 hour temperature change across the state as of late this afternoon.  Of course, temperatures yesterday were at or near record levels and temperatures this afternoon have actually only been slightly below normal, although the gusty northerly winds have certainly made it feel much cooler.  To put things in perspective, our afternoon high has been 47, but we were at 50 shortly after midnight so that is what will go into the record book for the high on this date.  Also, the morning low was 34 but we will be colder than that by midnight.  The normal values for today are 51/30.

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Thursday will be a more typical day in the sense that the coldest temperatures will occur during the early morning hours and the warmest during the afternoon.  And the day will get off to a very cold start as the gusty northerly winds today have not only brought in much cooler air, but also very dry air.  As a result, look for fair overnight skies and temperatures quickly falling through the 30s this evening and into the lower 20s by early morning.  Some of the normally cooler valleys will likely see temperatures in the teens to start the day, and although the winds will be light, wind chill values will likely be in the teens for many locations.

Thursday will have lots of sunshine along with a light easterly wind that morning but becoming more SE that afternoon.  Temperatures will struggle to get above the 50 degree mark with most locations only reaching the upper 40s for a daytime high. 

A stronger southerly wind for Thursday night should keep us from cooling much with upper 30s to low 40s to start the day on Friday.  Then, Friday and Saturday will be back to Spring-like conditions with strong southerly winds and daytime highs well into the 70s Friday afternoon and likely reaching the 80s Saturday afternoon which will set new records.  Mostly sunny skies will prevail for Friday but those strong southerly winds will return moisture and a low level cloud deck that night and into the morning hours of Saturday.  That also means a very warm start to Saturday morning and the clouds are expected to thin out from W-E during the day, so likely a pronounced W-E cloud gradient that afternoon.  Obviously, those low clouds are a wild card regarding how warm Saturday will be, but we should still set records that afternoon as you can see on our forecast page.

Keep in mind the strong southerly winds for Fri/Sat will also produce a very high fire danger as we remain very dry and the vegetation is dormant.

That will be followed by another dramatic cool-down for Sunday as a cold front moves across the state Saturday night.  But, that will actually only bring temperatures back closer to the seasonal norms going into next week, and in fact we are still forecasting temperatures to be somewhat above normal even though it will be much cooler than the Fri/Sat time frame due to the extreme warmth on those two days.  There will also be chances of showers on Sunday and into early next week along with mostly cloudy skies and a persistent northerly wind keeping temperatures more moderate.  However, the best chances of rain will be over the more southern counties as you can see on the 7 day QPF.

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Thought a brief look at the wind flow aloft would help explain the lack of really cold air in recent weeks and also the lack of rainfall across OK.  This first chart shows the wind flow aloft at about the 18,000’ level as of this afternoon.  Notice that the general flow is what we refer to as a zonal pattern which means the winds are generally blowing from W-E across the Pacific, onto the W Coast and then on across the U.S. and into the Atlantic.  The colors represent where the winds are the strongest, i.e. the jet stream.

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The next map has the same parameters, but is valid for Tuesday afternoon of next week.  Notice the flow has buckled somewhat with a stronger, more northerly component located near the Great Lakes and into the NE part of the country.  Notice, also, what I have labeled as a cut-off low aloft located near the Big Bend area of Texas.  That is the system that may produce some showers for Sunday into early next week as it gradually progresses on eastward, although most of the guidance is keeping its main influence confined to Texas and we will be on the northern fringe of any rain it produces.  Referring back to the 7 day QPF though, you can see why it is suggesting the heavier rains across Texas with only light amounts, if any at all, for most of OK because of the projected track of that feature. 

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Also, it is that persistent zonal or W-E flow aloft that has kept much of the west coast so wet and will continue to do so through this forecast period which is evident on the 7 day QPF.  Of interest to our weather though is the fact that this persistent zonal or W-E flow aloft keeps the really cold air bottled up far to the north of OK.  Occasionally, a system will come along to allow some colder air to surge southward, but it only lasts for a few days before temperatures quickly return to above normal levels such as what is happening this week.  A pattern in which a much more amplified N-S flow across the Arctic Circle is what we look for to produce the longer lived, more severe outbreaks of cold air and we have not seen much of that this winter.  As mentioned, this more zonal flow aloft is also responsible for very wet conditions along the west coast, but most of the moisture is wrung out of them as they cross the Rocky Mountains.  That means they do not have much to work with till they get well east of us which is why we have been so dry this winter.

As you can see on the 8-14 day guidance, this pattern looks to persist with a strong signal for temperatures on average to remain well above normal.  A drier than normal pattern also looks to persist through that time frame.

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So, stay tuned and check back for updates.

Dick Faurot